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Sample records for azospirillum brasilense tarrand

  1. Vertical movement of Azospirillum brasilense in soil

    International Nuclear Information System (INIS)

    Singh, Mohan; Lal, B.; Shrivastava, A.K.

    1993-01-01

    Plant growth promoting rhizobacteria like Azospirillum brasilense have considerable potential in increasing crop productivity. The success of bacterial inoculation in fields however, depends on their root colonizing ability. These bacteria, applied either through seed pelleting or directly to the soil are distributed along roots through active or passive movements. 32 P labelled A.brasilense has been used to study their movements in sandy loam soils. (author). 5 refs., 2 figs

  2. Hydrogen oxidation in Azospirillum brasilense

    Energy Technology Data Exchange (ETDEWEB)

    Tibelius, K.

    1984-01-01

    Hydrogen oxidation by Azospirillum brasilense Sp7 was studied in N/sub 2/-fixing and NH/sub 4//sup +/-grown batch cultures. The K/sub m/ for H/sub 2/ of O/sub 2/-dependent H/sup 3/H oxidation in whole cells was 9 uM. The rates of H/sup 3/H and H/sub 2/ oxidation were very similar, indicating that the initial H/sub 2/ activation step in the overall H/sub 2/ oxidation reaction was not rate-limiting and that H/sup 3/H oxidation was a valid measure of H/sub 2/-oxidation activity. Hydrogen-oxidation activity was inhibited irreversibly by air. In N-free cultures the O/sub 2/ optima for O/sub 2/-dependent H/sub 2/ oxidation, ranging from 0.5-1.25% O/sub 2/ depending on the phase of growth, were significantly higher than those of C/sub 2/H/sub 2/ reduction, 0.15-0.35%, suggesting that the H/sub 2/-oxidation system may have a limited ability to aid in the protection of nitrogenase against inactivation by O/sub 2/. Oxygen-dependent H/sub 2/ oxidation was inhibited by NO/sub 2//sup +/, NO, CO, and C/sub 2/H/sub 2/ with apparent K/sub 1/ values of 20, 0.4, 28, and 88 uM, respectively. Hydrogen-oxidation activity was 50 to 100 times higher in denitrifying cultures when the terminal electron acceptor for growth was N/sub 2/O rather than NO/sub 3//sup -/, possibly due to the irreversible inhibition of hydrogenase by NO/sub 2//sup -/ and NO in NO/sub 3//sup -/-grown cultures.

  3. [Biosynthesis of gold nanoparticles by Azospirillum brasilense].

    Science.gov (United States)

    Kupriashina, M A; Vetchinkina, E P; Burov, A M; Ponomareva, E G; Nikitina, V E

    2014-01-01

    Plant-associated nitrogen-fixing soil bacteria Azospirillum brasilense were shown to reduce the gold of chloroauric acid to elemental gold, resulting in formation of gold nanoparicles. Extracellular phenoloxidizing enzymes (laccases and Mn peroxidases) were shown to participate in reduction of Au+3 (HAuCl4) to Au(0). Transmission electron microscopy revealed accumulation of colloidal gold nanoparticles of diverse shape in the culture liquid of A. brasilense strains Sp245 and Sp7. The size of the electron-dense nanospheres was 5 to 50 nm, and the size of nanoprisms varied from 5 to 300 nm. The tentative mechanism responsible for formation of gold nanoparticles is discussed.

  4. Polymers selection for a liquid inoculant of Azospirillum brasilense ...

    African Journals Online (AJOL)

    In this study, we used a method of accelerated degradation to select a polymer and a concentration to maintain cell stability of a liquid inoculant based on the strain C16 Azospirillum brasilense. A screening at 45°C was made to compare the protectant effect of five polymers on the viability of the strain (p/v): carrageenan ...

  5. SEED INOCULATION WITH Azospirillum brasilense, ASSOCIATED WITH THE USE OF BIOREGULATORS IN MAIZE

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    ALESSANDRO DE LUCCA E BRACCINI

    2012-01-01

    Full Text Available The inoculation of seeds with the bacterium Azospirillum has been carried out in maize culture and other grasses. The application of growth bio-regulators is another technology whose results in maize culture have yet to become more widespread. Current study evaluates the agronomic effectiveness of seed inoculation with Azospirillum brasilense in maize, associated with the use of the growth regulator Stimulate ®. Triple hybrid maize CD 304 underwent the following treatments: 1 - control without nitrogen and without Azospirillum brasilense; 2 - Treatment without nitrogen but with Azospirillum brasilense; 3 - Treatment without nitrogen but with Azospirillum brasilense + Stimulate ®; 4 - Treatment with 50% of nitrogen dose recommended for maize culture; 5 - Treatment with 50% of nitrogen dose and inoculation with Azospirillum brasilense; 6 - Same as 5 but with Stimulate ®; 7 - Total N recommended; 8 - Total N recommended + Azospirillum brasilense ; 9 - Total N recommended + Azospirillum brasilense + Stimulate ®. The inoculation of maize seeds with Azospirillum brasilense increases plant height and grain yield when compared with rates in control. The use of 50% of N dose in sowing, associated with the inoculation of maize seeds with Azospirillum brasilense at 200 mL ha-1 (mixed to the seeds and associated with Stimulate ® (in foliar application, is viable.

  6. Network Analysis of Plasmidomes: The Azospirillum brasilense Sp245 Case

    Science.gov (United States)

    Fondi, Marco

    2014-01-01

    Azospirillum brasilense is a nitrogen-fixing bacterium living in association with plant roots. The genome of the strain Sp245, isolated in Brazil from wheat roots, consists of one chromosome and six plasmids. In this work, the A. brasilense Sp245 plasmids were analyzed in order to shed some light on the evolutionary pathways they followed over time. To this purpose, a similarity network approach was applied in order to identify the evolutionary relationships among all the A. brasilense plasmids encoded proteins; in this context a computational pipeline specifically devoted to the analysis and the visualization of the network-like evolutionary relationships among different plasmids molecules was developed. This information was supplemented with a detailed (in silico) functional characterization of both the connected (i.e., sharing homology with other sequences in the dataset) and the unconnected (i.e., not sharing homology) components of the network. Furthermore, the most likely source organism for each of the genes encoded by A. brasilense plasmids was checked, allowing the identification of possible trends of gene loss/gain in this microorganism. Data obtained provided a detailed description of the evolutionary landscape of the plasmids of A. brasilense Sp245, suggesting some of the molecular mechanisms responsible for the present-day structure of these molecules. PMID:25610702

  7. Inoculation of maize with Azospirillum brasilense in the seed furrow

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    Tâmara Prado de Morais

    2016-06-01

    Full Text Available ABSTRACT Several studies addressing the inoculation of cereals with diazotrophic microorganisms can be found in the literature. However, in many experiments, investigators have overlooked the feasibility of applying these microorganisms to the furrow together with the seed, and the effect of bacterial concentration on phytostimulation. The aim of this work was to evaluate the effect of doses of an inoculant based on Azospirillum brasilense, applied to the seed furrow when planting maize, combined with different doses of nitrogen fertiliser. The experiment was carried out in the field, in soil of the cerrado region of Brazil. An experimental design of randomised blocks in bands was adopted, comprising nitrogen (40, 100, 200 and 300 kg ha-1 and doses of an A. brasilense-based liquid inoculant applied to the seed furrow (0, 100, 200, 300 and 400 mL ha-1. The dose of 200 mL ha-1Azospirillum was noteworthy for grain production. This is the first report of the effective application of Azospirillum in the seed furrow when planting maize in the cerrado region of Brazil.

  8. Azospirillum brasilense, a Beneficial Soil Bacterium: Isolation and Cultivation.

    Science.gov (United States)

    Alexandre, Gladys

    2017-11-09

    Bacteria of the genus Azospirillum comprise 15 species to date, with A. brasilense the best studied species in the genus. Azospirillum are soil bacteria able to promote the growth of plants from 113 species spanning 35 botanical families. These non-pathogenic and beneficial bacteria are ubiquitous in soils and inhabit the roots of diverse plants. These bacteria are microaerophilic, able to fix nitrogen under free-living conditions, motile, and able to navigate in gradients of various chemicals, including oxygen. These physiological traits are used to isolate these soil bacteria from soil and plant root samples, providing isolates that can be used for studying microbial physiology and plant growth promotion. © 2017 by John Wiley & Sons, Inc. Copyright © 2017 John Wiley & Sons, Inc.

  9. Application of the Indirect Immunoperoxidase Stain Technique to the Flagella of Azospirillum brasilense

    Science.gov (United States)

    Hall, Patrick G.; Krieg, Noel R.

    1984-01-01

    An indirect immunoperoxidase stain was used to demonstrate by electron microscopy that an antigenic difference exists between the polar flagellum and the lateral flagella of Azospirillum brasilense ATCC 29145. Images PMID:16346482

  10. Directed mutagenesis affects recombination in Azospirillum brasilense nif genes

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    C.P. Nunes

    2000-12-01

    Full Text Available In order to improve the gene transfer/mutagenesis system for Azospirillum brasilense, gene-cartridge mutagenesis was used to replace the nifD gene with the Tn5 kanamycin resistance gene. The construct was transferred to A. brasilense by electrotransformation. Of the 12 colonies isolated using the suicide plasmid pSUP202 as vector, only four did not show vector integration into the chromosome. Nevertheless, all 12 colonies were deficient in acetylene reduction, indicating an Nif- phenotype. Four Nif- mutants were analyzed by Southern blot, using six different probes spanning the nif and Km r genes and the plasmid vector. Apparently, several recombination events occurred in the mutant genomes, probably caused mainly by gene disruption owing to the mutagenesis technique used: resistance gene-cartridge mutagenesis combined with electrotransformation.Com o objetivo de melhorar os sistemas de transferência gênica e mutagênese para Azospirillum brasilense, a técnica de mutagênese através do uso de um gene marcador ("gene-cartridge mutagenesis" foi utilizada para substituir a região genômica de A. brasilense correspondente ao gene nifD por um segmento de DNA do transposon Tn5 contendo o gene que confere resistência ao antibiótico canamicina. A construção foi transferida para a linhagem de A. brasilense por eletrotransformação. Doze colônias transformantes foram isoladas com o plasmídeo suicida pSUP202 servindo como vetor. Dessas, somente quatro não possuíam o vetor integrado no cromossomo da bactéria. Independentemente da integração ou não do vetor, as 12 colônias foram deficientes na redução do gás acetileno, evidenciando o fenótipo Nif -. Quatro mutantes Nif - foram analisados através da técnica de Southern blot, utilizando-se seis diferentes fragmentos contendo genes nif, de resistência à canamicina e do vetor como sondas. Os resultados sugerem a ocorrência de eventos recombinacionais variados no genoma dos mutantes. A

  11. Carotenoid production and phenotypic variation in Azospirillum brasilense.

    Science.gov (United States)

    Brenholtz, Gal Reem; Tamir-Ariel, Dafna; Okon, Yaacov; Burdman, Saul

    2017-06-01

    We assessed the occurrence of phenotypic variation in Azospirillum brasilense strains Sp7, Cd, Sp245, Az39 and phv2 during growth in rich media, screening for variants altered in colony pigmentation or extracellular polysaccharide (EPS) production. Previous studies showed that EPS-overproducing variants of Sp7 appear frequently following starvation or growth in minimal medium. In contrast, no such variants were detected during growth in rich media in the tested strains except for few variants of phv2. Regarding alteration in colony pigmentation (from pink to white in strain Cd and from white to pink in the others), strain Sp7 showed a relatively high frequency of variation (0.009-0.026%). Strain Cd showed a lower frequency of alteration in pigmentation (0-0.008%), and this type of variation was not detected in the other strains. In A. brasilense, carotenoid synthesis is controlled by two RpoE sigma factors and their cognate ChrR anti-sigma factors, the latter acting as negative regulators of carotenoid synthesis. Here, all tested (n = 28) pink variants of Sp7 carried mutations in one of the anti-sigma factor genes, chrR1. Our findings indicate that, in A. brasilense, phenotypic variation is strain- and environment-dependent and support the central role of ChrR1 in regulation of carotenoid production. Copyright © 2017 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.

  12. Energy Taxis Is the Dominant Behavior in Azospirillum brasilense

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    Alexandre, Gladys; Greer, Suzanne E.; Zhulin, Igor B.

    2000-01-01

    Energy taxis encompasses aerotaxis, phototaxis, redox taxis, taxis to alternative electron acceptors, and chemotaxis to oxidizable substrates. The signal for this type of behavior is originated within the electron transport system. Energy taxis was demonstrated, as a part of an overall behavior, in several microbial species, but it did not appear as the dominant determinant in any of them. In this study, we show that most behavioral responses proceed through this mechanism in the alpha-proteobacterium Azospirillum brasilense. First, chemotaxis to most chemoeffectors typical of the azospirilla habitat was found to be metabolism dependent and required a functional electron transport system. Second, other energy-related responses, such as aerotaxis, redox taxis, and taxis to alternative electron acceptors, were found in A. brasilense. Finally, a mutant lacking a cytochrome c oxidase of the cbb3 type was affected in chemotaxis, redox taxis, and aerotaxis. Altogether, the results indicate that behavioral responses to most stimuli in A. brasilense are triggered by changes in the electron transport system. PMID:11029423

  13. Aggregation of the rhizospheric bacterium Azospirillum brasilense in response to oxygen

    Science.gov (United States)

    Abdoun, Hamid; McMillan, Mary; Pereg, Lily

    2016-04-01

    Azospirillum brasilense spp. have ecological, scientific and agricultural importance. As model plant growth promoting rhizobacteria they interact with a large variety of plants, including important food and cash crops. Azospirillum strains are known for their production of plant growth hormones that enhance root systems and for their ability to fix nitrogen. Azospirillum cells transform in response to environmental cues. The production of exopolysaccharides and cell aggregation during cellular transformation are important steps in the attachment of Azospirillum to roots. We investigate signals that induce cellular transformation and aggregation in the Azospirillum and report on the importance of oxygen to the process of aggregation in this rhizospheric bacterium.

  14. Accessing inoculation methods of maize and wheat with Azospirillum brasilense.

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    Fukami, Josiane; Nogueira, Marco Antonio; Araujo, Ricardo Silva; Hungria, Mariangela

    2016-03-01

    The utilization of inoculants containing Azospirillum is becoming more popular due to increasing reports of expressive gains in grain yields. However, incompatibility with pesticides used in seed treatments represents a main limitation for a successful inoculation. Therefore, in this study we searched for alternatives methods for seed inoculation of maize and wheat, aiming to avoid the direct contact of bacteria with pesticides. Different doses of inoculants containing Azospirillum brasilense were employed to perform inoculation in-furrow, via soil spray at sowing and via leaf spray after seedlings had emerged, in comparison to seed inoculation. Experiments were conducted first under greenhouse controlled conditions and then confirmed in the field at different locations in Brazil. In the greenhouse, most parameters measured responded positively to the largest inoculant dose used in foliar sprays, but benefits could also be observed from both in-furrow and soil spray inoculation. However, our results present evidence that field inoculation with plant-growth promoting bacteria must consider inoculant doses, and point to the need of fine adjustments to avoid crossing the threshold of growth stimulation and inhibition. All inoculation techniques increased the abundance of diazotrophic bacteria in plant tissues, and foliar spray improved colonization of leaves, while soil inoculations favored root and rhizosphere colonization. In field experiments, inoculation with A. brasilense allowed for a 25 % reduction in the need for N fertilizers. Our results have identified alternative methods of inoculation that were as effective as the standard seed inoculation that may represent an important strategy to avoid the incompatibility between inoculant bacteria and pesticides employed for seed treatment.

  15. Irrigated wheat subjected to inoculation with Azospirillum brasilense and nitrogen doses as top-dressing

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    Cleiton J. Alves

    Full Text Available ABSTRACT The use of Azospirillum brasilense in the wheat crop still presents contradictory results; thus, it is necessary to identify ideal conditions to obtain satisfactory results. The objective of this study was to investigate the interaction between Azospirillum brasilense and nitrogen doses in a wheat cultivar, conducted with irrigation in the Cerrado region of Mato Grosso do Sul. The experimental design was randomized blocks with a 4 x 2 factorial scheme, four nitrogen doses (0, 40, 80 and 120 kg ha-1 applied as top-dressing, associated or not with inoculation of wheat seeds with Azospirillum brasilense. The results show that there was no interaction between N and inoculation. The isolated effect of Azospirillum brasilense promotes an increase in plant height and number of grains per spike. Nitrogen doses promotes significant increases in leaf N content, plant height, number of grains per spike, number of spikes per square meter and grain yield. The conditions under which the experiment was conducted favored the development of the crop, not interfering with grain yield due the inoculation with Azospirillum brasilense.

  16. Economic analysis of corn inoculated with Azospirillum brasilense associated with nitrogen sources and doses

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    Fernando Shintate Galindo

    2017-08-01

    Full Text Available Azospirillum brasilense is a bacterium known for its biological nitrogen fixation (BNF in corn crops. However, there is a lack of comprehensive research defining how much mineral N should be applied to maximize the efficiency of BNF and attain high, economically sustainable yields. Moreover, it would be interesting to investigate whether adding urea with NBPT urease inhibitor might increase BNF in grasses. Therefore, the aim of this study was to determine the effect of inoculation with Azospirillum brasilense associated with N sources and doses in a Cerrado biome soil by evaluating the grain yield of irrigated corn in economic terms. The experiment was conducted in Selvíria, MS, Brazil under a no-till system on a Latossolo Vermelho distrófico (Oxisol. The experiment was set up as a randomized block design with four replications in a 2 × 5 × 2 factorial arrangement consisting of two sources of N (urea and urea with NBPT urease enzyme inhibitor and five N doses applied as top-dressing (0, 50, 100, 150, and 200 kg ha-1, with and without the inoculation of seeds with A. brasilense. Inoculation with Azospirillum brasilense makes corn growth much more profitable, irrespective of the dose and source of N. Addition of 200 kg ha-1 N in the form of conventional urea coupled with inoculation with Azospirillum brasilense increases grain yield; however, the highest economic return is obtained with N applied at 100 kg ha-1 with conventional urea and inoculation.

  17. brasilense nativa de Tamaulipas, México

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    J. L. Hernández-Mendoza

    2008-01-01

    Full Text Available La bacteria Azospirillum brasilense [Tarrand et al., 1979] metaboliza el triptófano y produce diversos metabolitos; entre ellos, el ácido indolacético. En este trabajo se utilizó la cepa CBG 497 de A. brasilense aislada de maíz para identificar los metabolitos producidos a partir de triptófano en laboratorio. Entre los metabolitos identificados destacan los ácidos antranílico e indolacético. El ácido antranílico es un compuesto intermediario en la síntesis y degradación del triptófano y, junto con el ácido indolacético, estaría involucrado en la capacidad promotora del crecimiento vegetal de A. brasilense

  18. Oxidative and antioxidative responses in the wheat-Azospirillum brasilense interaction.

    Science.gov (United States)

    Méndez-Gómez, Manuel; Castro-Mercado, Elda; Alexandre, Gladys; García-Pineda, Ernesto

    2016-03-01

    Azospirillum is a plant growth-promoting rhizobacteria (PGPR) able to enhance the growth of wheat. The aim of this study was to test the effect of Azospirillum brasilense cell wall components on superoxide (O2·(-)) production in wheat roots and the effect of oxidative stress on A. brasilense viability. We found that inoculation with A. brasilense reduced O2·(-) levels by approx. 30 % in wheat roots. Inoculation of wheat with papain-treated A. brasilense, a Cys protease, notably increased O2·(-) production in all root tissues, as was observed by the nitro blue tetrazolium (NBT) reduction. However, a 24-h treatment with rhizobacteria lipopolysaccharides (50 and 100 μg/mL) alone did not affect the pattern of O2·(-) production. Analysis of the effect of plant cell wall components on A. brasilense oxidative enzyme activity showed no changes in catalase activity but a decrease in superoxide dismutase activity in response to polygalacturonic acid treatment. Furthermore, A. brasilense growth was only affected by high concentrations of H2O2 or paraquat, but not by sodium nitroprusside. Our results suggest that rhizobacterial cell wall components play an important role in controlling plant cell responses and developing tolerance of A. brasilense to oxidative stress produced by the plant.

  19. FTIR spectroscopic study of biofilms formed by the rhizobacterium Azospirillum brasilense Sp245 and its mutant Azospirillum brasilense Sp245.1610

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    Tugarova, Anna V.; Scheludko, Andrei V.; Dyatlova, Yulia A.; Filip'echeva, Yulia A.; Kamnev, Alexander A.

    2017-07-01

    Biofilms are spatially and metabolically structured communities of microorganisms, representing a mode of their existence which is ubiquitous in nature, with cells localised within an extracellular biopolymeric matrix, attached to each other, at an interface. For plant-growth-promoting rhizobacteria (PGPR), the formation of biofilms is of special importance due to their primary localisation at the surface of plant root systems. In this work, FTIR spectroscopy was used, for the first time for bacteria of the genus Azospirillum, to comparatively study 6-day-mature biofilms formed on the surface of ZnSe discs by the rhizobacterium Azospirillum brasilense Sp245 and its mutant A. brasilense Sp245.1610. The mutant strain, having an Omegon Km insertion in the gene of lipid metabolism fabG1 on the plasmid AZOBR_p1, as compared to the wild-type strain Sp245 (see http://dx.doi.org/10.1134/S1022795413110112)

  20. Maize growth in response to Azospirillum brasilense, Rhizobium tropici, molybdenum and nitrogen

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    Angelita A. C. Picazevicz

    Full Text Available ABSTRACT The objective of this research was to evaluate the effect of Azospirillum brasilense, Rhizobium tropici, nitrogen (N and molybdenum (Mo fertilization on maize growth. The experiment was carried out in a greenhouse from October to November 2015, in a completely randomized design, in 2 x 2 x 2 x 5 factorial scheme, with 5 replicates, corresponding to the absence and presence of Azospirillum brasilense, Rhizobium tropici, N (30 kg ha-1 and five Mo doses (0, 7.5, 15.0, 22.5 and 30.0 g ha-1. The analyzed variables were: plant height, basal stem diameter, dry biomass of shoots, roots, total and N accumulated in the shoots. There was double or triple interaction between N fertilization, Azospirillum brasilense and Rhizobium tropici for the evaluated variables. However, isolated and/or combined effect of Mo was not observed. Seed inoculation with Azospirillum brasilense as well as their co-inoculation with Rhizobium tropici in the absence of N fertilization was efficient to increase plant growth. Soil N fertilization at sowing was less efficient in promoting plant growth than when it was combined with seed inoculation with Rhizobium tropici.

  1. Azospirillum brasilense ameliorates the response of Arabidopsis thaliana to drought mainly via enhancement of ABA levels.

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    Cohen, Ana C; Bottini, Rubén; Pontin, Mariela; Berli, Federico J; Moreno, Daniela; Boccanlandro, Hernán; Travaglia, Claudia N; Piccoli, Patricia N

    2015-01-01

    Production of phytohormones is one of the main mechanisms to explain the beneficial effects of plant growth-promoting rhizobacteria (PGPR) such as Azospirillum sp. The PGPRs induce plant growth and development, and reduce stress susceptibility. However, little is known regarding the stress-related phytohormone abscisic acid (ABA) produced by bacteria. We investigated the effects of Azospirillum brasilense Sp 245 strain on Arabidopsis thaliana Col-0 and aba2-1 mutant plants, evaluating the morphophysiological and biochemical responses when watered and in drought. We used an in vitro-grown system to study changes in the root volume and architecture after inoculation with Azospirillum in Arabidopsis wild-type Col-0 and on the mutant aba2-1, during early growth. To examine Arabidopsis development and reproductive success as affected by the bacteria, ABA and drought, a pot experiment using Arabidopsis Col-0 plants was also carried out. Azospirillum brasilense augmented plant biomass, altered root architecture by increasing lateral roots number, stimulated photosynthetic and photoprotective pigments and retarded water loss in correlation with incremented ABA levels. As well, inoculation improved plants seed yield, plants survival, proline levels and relative leaf water content; it also decreased stomatal conductance, malondialdehyde and relative soil water content in plants submitted to drought. Arabidopsis inoculation with A. brasilense improved plants performance, especially in drought. © 2014 Scandinavian Plant Physiology Society.

  2. [Detection of putative polysaccharide biosynthesis genes in Azospirillum brasilense strains from serogroups I and II].

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    Petrova, L P; Prilipov, A G; Katsy, E I

    2017-01-01

    It is known that in Azospirillum brasilense strains Sp245 and SR75 included in serogroup I, the repeat units of their O-polysaccharides consist of five residues of D-rhamnose, and in strain SR15, of four; and the heteropolymeric O-polysaccharide of A. brasilense type strain Sp7 from serogroup II contains not less than five types of repeat units. In the present work, a complex of nondegenerate primers to the genes of A. brasilense Sp245 plasmids AZOBR_p6, AZOBR_p3, and AZOBR_p2, which encode putative enzymes for the biosynthesis of core oligosaccharide and O-polysaccharide of lipopolysaccharide, capsular polysaccharides, and exopolysaccharides, was proposed. By using the designed primers, products of the expected sizes were synthesized in polymerase chain reactions on genomic DNA of A. brasilense Sp245, SR75, SR15, and Sp7 in 36, 29, 23, and 12 cases, respectively. As a result of sequencing of a number of amplicons, a high (86–99%) level of identity of the corresponding putative polysaccharide biosynthesis genes in three A. brasilense strains from serogroup I was detected. In a blotting-hybridization reaction with the biotin-labeled DNA of the A. brasilense gene AZOBR_p60122 coding for putative permease of the ABC transporter of polysaccharides, localization of the homologous gene in ~120-MDa plasmids of the bacteria A. brasilense SR15 and SR75 was revealed.

  3. Bacteriophage Prevalence in the Genus Azospirillum and Analysis of the First Genome Sequence of an Azospirillum brasilense Integrative Phage▿

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    Boyer, Mickaël; Haurat, Jacqueline; Samain, Sylvie; Segurens, Béatrice; Gavory, Frédérick; González, Víctor; Mavingui, Patrick; Rohr, René; Bally, René; Wisniewski-Dyé, Florence

    2008-01-01

    The prevalence of bacteriophages was investigated in 24 strains of four species of plant growth-promoting rhizobacteria belonging to the genus Azospirillum. Upon induction by mitomycin C, the release of phage particles was observed in 11 strains from three species. Transmission electron microscopy revealed two distinct sizes of particles, depending on the identity of the Azospirillum species, typical of the Siphoviridae family. Pulsed-field gel electrophoresis and hybridization experiments carried out on phage-encapsidated DNAs revealed that all phages isolated from A. lipoferum and A. doebereinerae strains had a size of about 10 kb whereas all phages isolated from A. brasilense strains displayed genome sizes ranging from 62 to 65 kb. Strong DNA hybridizing signals were shown for most phages hosted by the same species whereas no homology was found between phages harbored by different species. Moreover, the complete sequence of the A. brasilense Cd bacteriophage (ΦAb-Cd) genome was determined as a double-stranded DNA circular molecule of 62,337 pb that encodes 95 predicted proteins. Only 14 of the predicted proteins could be assigned functions, some of which were involved in DNA processing, phage morphogenesis, and bacterial lysis. In addition, the ΦAb-Cd complete genome was mapped as a prophage on a 570-kb replicon of strain A. brasilense Cd, and a region of 27.3 kb of ΦAb-Cd was found to be duplicated on the 130-kb pRhico plasmid previously sequenced from A. brasilense Sp7, the parental strain of A. brasilense Cd. PMID:18065619

  4. Bacteriophage prevalence in the genus Azospirillum and analysis of the first genome sequence of an Azospirillum brasilense integrative phage.

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    Boyer, Mickaël; Haurat, Jacqueline; Samain, Sylvie; Segurens, Béatrice; Gavory, Frédérick; González, Víctor; Mavingui, Patrick; Rohr, René; Bally, René; Wisniewski-Dyé, Florence

    2008-02-01

    The prevalence of bacteriophages was investigated in 24 strains of four species of plant growth-promoting rhizobacteria belonging to the genus Azospirillum. Upon induction by mitomycin C, the release of phage particles was observed in 11 strains from three species. Transmission electron microscopy revealed two distinct sizes of particles, depending on the identity of the Azospirillum species, typical of the Siphoviridae family. Pulsed-field gel electrophoresis and hybridization experiments carried out on phage-encapsidated DNAs revealed that all phages isolated from A. lipoferum and A. doebereinerae strains had a size of about 10 kb whereas all phages isolated from A. brasilense strains displayed genome sizes ranging from 62 to 65 kb. Strong DNA hybridizing signals were shown for most phages hosted by the same species whereas no homology was found between phages harbored by different species. Moreover, the complete sequence of the A. brasilense Cd bacteriophage (phiAb-Cd) genome was determined as a double-stranded DNA circular molecule of 62,337 pb that encodes 95 predicted proteins. Only 14 of the predicted proteins could be assigned functions, some of which were involved in DNA processing, phage morphogenesis, and bacterial lysis. In addition, the phiAb-Cd complete genome was mapped as a prophage on a 570-kb replicon of strain A. brasilense Cd, and a region of 27.3 kb of phiAb-Cd was found to be duplicated on the 130-kb pRhico plasmid previously sequenced from A. brasilense Sp7, the parental strain of A. brasilense Cd.

  5. Technical and economic viability of co-inoculation with Azospirillum brasilense in soybean cultivars in the Cerrado

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    Fernando S. Galindo

    Full Text Available ABSTRACT Biological nitrogen fixation (BNF efficiency can be increased by co-inoculation with bradyrhizobia and Azospirillum brasilense, allowing even greater uptake of water and nutrients, leading to higher yields. Thus, this study aimed to evaluate the technical and economic viability of soybean in the Cerrado, according to the cultivars and co-inoculation with Azospirillum brasilense. The experiment was conducted in Selvíria, MS, in no-tillage system, in Oxisol, arranged in a randomized block design in a 2 x 2 factorial scheme with two cultivars (‘Potência’ and ‘Valiosa’, with and without co-inoculation with Azospirillum brasilense in the seed. Co-inoculation with A. brasilense increases grain yield in the cultivars ‘Potência’ and ‘Valiosa’, being economically viable. However, using the cultivar ‘Potência’ co-inoculated led to the highest profitability.

  6. Fourier transform infrared spectroscopic study of intact cells of the nitrogen-fixing bacterium Azospirillum brasilense

    Science.gov (United States)

    Kamnev, A. A.; Ristić, M.; Antonyuk, L. P.; Chernyshev, A. V.; Ignatov, V. V.

    1997-06-01

    The data of Fourier transform infrared (FTIR) spectroscopic measurements performed on intact cells of the soil nitrogen-fixing bacterium Azospirillum brasilense grown in a standard medium and under the conditions of an increased metal uptake are compared and discussed. The structural FTIR information obtained is considered together with atomic absorption spectrometry (AAS) data on the content of metal cations in the bacterial cells. Some methodological aspects concerning preparation of bacterial cell samples for FTIR measurements are also discussed.

  7. Purification and binding analysis of the nitrogen fixation regulatory NifA protein from Azospirillum brasilense

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    L.M.P. Passaglia

    1998-11-01

    Full Text Available NifA protein activates transcription of nitrogen fixation operons by the alternative sigma54 holoenzyme form of RNA polymerase. This protein binds to a well-defined upstream activator sequence (UAS located at the -200/-100 position of nif promoters with the consensus motif TGT-N10-ACA. NifA of Azospirillum brasilense was purified in the form of a glutathione-S-transferase (GST-NifA fusion protein and proteolytic release of GST yielded inactive and partially soluble NifA. However, the purified NifA was able to induce the production of specific anti-A. brasilense NifA-antiserum that recognized NifA from A. brasilense but not from K. pneumoniae. Both GST-NifA and NifA expressed from the E. coli tac promoter are able to activate transcription from the nifHDK promoter but only in an A. brasilense background. In order to investigate the mechanism that regulates NifA binding capacity we have used E. coli total protein extracts expressing A. brasilense nifA in mobility shift assays. DNA fragments carrying the two overlapping, wild-type or mutated UAS motifs present in the nifH promoter region revealed a retarded band of related size. These data show that the binding activity present in the C-terminal domain of A. brasilense NifA protein is still functional even in the presence of oxygen.

  8. Transcriptome analysis of the rhizosphere bacterium Azospirillum brasilense reveals an extensive auxin response.

    Science.gov (United States)

    Van Puyvelde, Sandra; Cloots, Lore; Engelen, Kristof; Das, Frederik; Marchal, Kathleen; Vanderleyden, Jos; Spaepen, Stijn

    2011-05-01

    The rhizosphere bacterium Azospirillum brasilense produces the auxin indole-3-acetic acid (IAA) through the indole-3-pyruvate pathway. As we previously demonstrated that transcription of the indole-3-pyruvate decarboxylase (ipdC) gene is positively regulated by IAA, produced by A. brasilense itself or added exogenously, we performed a microarray analysis to study the overall effects of IAA on the transcriptome of A. brasilense. The transcriptomes of A. brasilense wild-type and the ipdC knockout mutant, both cultured in the absence and presence of exogenously added IAA, were compared.Interfering with the IAA biosynthesis/homeostasis in A. brasilense through inactivation of the ipdC gene or IAA addition results in much broader transcriptional changes than anticipated. Based on the multitude of changes observed by comparing the different transcriptomes, we can conclude that IAA is a signaling molecule in A. brasilense. It appears that the bacterium, when exposed to IAA, adapts itself to the plant rhizosphere, by changing its arsenal of transport proteins and cell surface proteins. A striking example of adaptation to IAA exposure, as happens in the rhizosphere, is the upregulation of a type VI secretion system (T6SS) in the presence of IAA. The T6SS is described as specifically involved in bacterium-eukaryotic host interactions. Additionally, many transcription factors show an altered regulation as well, indicating that the regulatory machinery of the bacterium is changing.

  9. Seed inoculation with Azospirillum brasilense and N fertilization of corn in the Cerrado biome

    Directory of Open Access Journals (Sweden)

    Ana Carolina Pereira de Vasconcelos

    Full Text Available ABSTRACT There is a great interest to reduce doses and increase efficiency of inputs in agriculture. One alternative to lower doses of N fertilizers in corn is seed inoculation with diazotrophic bacteria, which can fix atmospheric N in soil. This study aimed to evaluate the effect of N doses-in the absence and presence of Azospirillum brasilense-on plant nutritional status at different growth stages and on seed yield of corn. The experiment was conducted during the 2011/2012 production season on a typical cerrado soil in Uberlândia, Triângulo Mineiro. The experimental design was randomized blocks with six repetitions. The treatments consisted of five N doses and the absence or presence of Azospirillum brasilense (100 mL ha-1 as a seed inoculant. A commercial product with minimum concentration of 2x108 CFU mL-1 100 mL ha-1 was used. Inoculation with Azospirillum brasilense did not significantly affect corn macronutrient content and yield, except for foliar calcium and potassium at 200 kg N ha-1 at the V8 stage. Corn yield increased with N doses up to 150 kg N ha-1.

  10. [Determination of Azospirillum Brasilense Cells With Bacteriophages via Electrooptical Analysis of Microbial Suspensions].

    Science.gov (United States)

    Gulii, O I; Karavayeva, O A; Pavlii, S A; Sokolov, O I; Bunin, V D; Ignatov, O V

    2015-01-01

    The dependence-of changes in the electrooptical properties of Azospirillum brasilense cell suspension Sp7 during interaction with bacteriophage ΦAb-Sp7 on the number and time of interactions was studied. Incubation of cells with bacteriophage significantly changed the electrooptical signal within one minute. The selective effect of bacteriophage ΦAb on 18 strains of bacteria of the genus Azospirillum was studied: A. amazonense Ami4, A. brasilense Sp7, Cd, Sp107, Sp245, Jm6B2, Brl4, KR77, S17, S27, SR55, SR75, A. halopraeferans Au4, A. irakense KBC1, K A3, A. lipoferum Sp59b, SR65 and RG20a. We determined the limit of reliable determination of microbial cells infected with bacteriophage: - 10(4) cells/mL. The presence of foreign cell cultures of E. coli B-878 and E. coli XL-1 did not complicate the detection of A brasilense Sp7 cells with the use of bacteriophage ΦAb-Sp7. The results demonstrated that bacteriophage (ΦAb-Sp7 can be used for the detection of Azospirillum microbial cells via t electrooptical analysis of cell suspensions.

  11. Labeled Azospirillum brasilense wild type and excretion-ammonium strains in association with barley roots.

    Science.gov (United States)

    Santos, Adrian Richard Schenberger; Etto, Rafael Mazer; Furmam, Rafaela Wiegand; Freitas, Denis Leandro de; Santos, Karina Freire d'Eça Nogueira; Souza, Emanuel Maltempi de; Pedrosa, Fábio de Oliveira; Ayub, Ricardo Antônio; Steffens, Maria Berenice Reynaud; Galvão, Carolina Weigert

    2017-09-01

    Soil bacteria colonization in plants is a complex process, which involves interaction between many bacterial characters and plant responses. In this work, we labeled Azospirillum brasilense FP2 (wild type) and HM053 (excretion-ammonium) strains by insertion of the reporter gene gusA-kanamycin into the dinitrogenase reductase coding gene, nifH, and evaluated bacteria colonization in barley (Hordeum vulgare). In addition, we determined inoculation effect based on growth promotion parameters. We report an uncommon endophytic behavior of A. brasilense Sp7 derivative inside the root hair cells of barley and highlight the promising use of A. brasilense HM053 as plant growth-promoting bacterium. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  12. [Biofilm Formation by the Nonflagellated flhB1 Mutant of Azospirillum brasilense Sp245].

    Science.gov (United States)

    Shelud'ko, A V; Filip'echeva, Yu A; Shumiliva, E M; Khlebtsov, B N; Burov, A M; Petrova, L P; Katsy, E I

    2015-01-01

    Azospirillum brasilense Sp245 with mixed flagellation are able to form biofilms on various surfaces. A nonflagellated mutant of this strain with inactivated chromosomal copy of the flhB gene (flhB1) was shown to exhibit specific traits at the later stages of biofilm formation on a hydrophilic (glass) surface. Mature biofilms of the flhB1::Omegon-Km mutant Sp245.1063 were considerably thinner than those of the parent strain Sp245. The biofilms of the mutant were more susceptible to the forces of hydrodynamic shear. A. brasilense Sp245 cells in biofilms were not found to possess lateral flagella. Cells with polar flagella were, however, revealed by atomic force microscopy of mature native biofilms of strain Sp245. Preservation of a polar flagellum (probably nonmotile) on the cells of A. brasilense Sp245 may enhance the biofilm stability.

  13. [Factors inducing transition from growth to dormancy in rhizobacteria Azospirillum brasilense].

    Science.gov (United States)

    Kushneruk, M A; Tugarova, A V; Il'chukova, A V; Slavkina, E A; Starichkova, N I; Bogatyrev, V A; Antoniuk, L P

    2013-01-01

    The factors suppressing division of the cells of the rhizobacterium Azospirillum brasilense and inducing their transition to a dormant state were analyzed. These included the presence of hexylresorcinol or heavy metals (Cu and Co) in the medium, oxygen stress, and transfer of the cells into the physiological saline or phosphate buffer solution. The results were used to develop a protocol for obtaining of uncultured cells of A. brasilense Sp245, a natural symbiont of wheat. The cells lost their ability to grow on synthetic agar medium, but could revert to growth when incubated in freshly prepared liquid medium. Needle-shaped crystals differing from struvite, which has been previously reported for this strain, were found in the dormant culture of A. brasilense Sp245.

  14. Denitrification-derived nitric oxide modulates biofilm formation in Azospirillum brasilense.

    Science.gov (United States)

    Arruebarrena Di Palma, Andrés; Pereyra, Cintia M; Moreno Ramirez, Lizbeth; Xiqui Vázquez, María L; Baca, Beatriz E; Pereyra, María A; Lamattina, Lorenzo; Creus, Cecilia M

    2013-01-01

    Azospirillum brasilense is a rhizobacterium that provides beneficial effects on plants when they colonize roots. The formation of complex bacterial communities known as biofilms begins with the interaction of planktonic cells with surfaces in response to appropriate signals. Nitric oxide (NO) is a signaling molecule implicated in numerous processes in bacteria, including biofilm formation or dispersion, depending on genera and lifestyle. Azospirillum brasilense Sp245 produces NO by denitrification having a role in root growth promotion. We analyzed the role of endogenously produced NO on biofilm formation in A. brasilense Sp245 and in a periplasmic nitrate reductase mutant (napA::Tn5; Faj164) affected in NO production. Cells were statically grown in media with nitrate or ammonium as nitrogen sources and examined for biofilm formation using crystal violet and by confocal laser microscopy. Both strains formed biofilms, but the mutant produced less than half compared with the wild type in nitrate medium showing impaired nitrite production in this condition. NO measurements in biofilm confirmed lower values in the mutant strain. The addition of a NO donor showed that NO influences biofilm formation in a dose-dependent manner and reverses the mutant phenotype, indicating that Nap positively regulates the formation of biofilm in A. brasilense Sp245. © 2012 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

  15. Key physiological properties contributing to rhizosphere adaptation and plant growth promotion abilities of Azospirillum brasilense.

    Science.gov (United States)

    Fibach-Paldi, Sharon; Burdman, Saul; Okon, Yaacov

    2012-01-01

    Azospirillum brasilense is a plant growth promoting rhizobacterium (PGPR) that is being increasingly used in agriculture in a commercial scale. Recent research has elucidated key properties of A. brasilense that contribute to its ability to adapt to the rhizosphere habitat and to promote plant growth. They include synthesis of the auxin indole-3-acetic acid, nitric oxide, carotenoids, and a range of cell surface components as well as the ability to undergo phenotypic variation. Storage and utilization of polybetahydroxyalkanoate polymers are important for the shelf life of the bacteria in production of inoculants, products containing bacterial cells in a suitable carrier for agricultural use. Azospirillum brasilense is able to fix nitrogen, but despite some controversy, as judging from most systems evaluated so far, contribution of fixed nitrogen by this bacterium does not seem to play a major role in plant growth promotion. In this review, we focus on recent advances in the understanding of physiological properties of A. brasilense that are important for rhizosphere performance and successful interactions with plant roots. © 2011 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

  16. Quantification of Azospirillum brasilense FP2 Bacteria in Wheat Roots by Strain-Specific Quantitative PCR.

    Science.gov (United States)

    Stets, Maria Isabel; Alqueres, Sylvia Maria Campbell; Souza, Emanuel Maltempi; Pedrosa, Fábio de Oliveira; Schmid, Michael; Hartmann, Anton; Cruz, Leonardo Magalhães

    2015-10-01

    Azospirillum is a rhizobacterial genus containing plant growth-promoting species associated with different crops worldwide. Azospirillum brasilense strains exhibit a growth-promoting effect by means of phytohormone production and possibly by N2 fixation. However, one of the most important factors for achieving an increase in crop yield by plant growth-promoting rhizobacteria is the survival of the inoculant in the rhizosphere, which is not always achieved. The objective of this study was to develop quantitative PCR protocols for the strain-specific quantification of A. brasilense FP2. A novel approach was applied to identify strain-specific DNA sequences based on a comparison of the genomic sequences within the same species. The draft genome sequences of A. brasilense FP2 and Sp245 were aligned, and FP2-specific regions were filtered and checked for other possible matches in public databases. Strain-specific regions were then selected to design and evaluate strain-specific primer pairs. The primer pairs AzoR2.1, AzoR2.2, AzoR5.1, AzoR5.2, and AzoR5.3 were specific for the A. brasilense FP2 strain. These primer pairs were used to monitor quantitatively the population of A. brasilense in wheat roots under sterile and nonsterile growth conditions. In addition, coinoculations with other plant growth-promoting bacteria in wheat were performed under nonsterile conditions. The results showed that A. brasilense FP2 inoculated into wheat roots is highly competitive and achieves high cell numbers (∼10(7) CFU/g [fresh weight] of root) in the rhizosphere even under nonsterile conditions and when coinoculated with other rhizobacteria, maintaining the population at rather stable levels for at least up to 13 days after inoculation. The strategy used here can be applied to other organisms whose genome sequences are available. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

  17. Reorganization of Azospirillum brasilense cell membrane is mediated by lipid composition adjustment to maintain optimal fluidity during water deficit.

    Science.gov (United States)

    Cesari, A B; Paulucci, N S; Biasutti, M A; Reguera, Y B; Gallarato, L A; Kilmurray, C; Dardanelli, M S

    2016-01-01

    We study the Azospirillum brasilense tolerance to water deficit and the dynamics of adaptive process at the level of the membrane. Azospirillum brasilense was exposed to polyethylene glycol (PEG) growth and PEG shock. Tolerance, phospholipids and fatty acid (FA) composition and membrane fluidity were determined. Azospirillum brasilense was able to grow in the presence of PEG; however, its viability was reduced. Cells grown with PEG showed membrane fluidity similar to those grown without, the lipid composition was modified, increasing phosphatidylcholine and decreasing phosphatidylethanolamine amounts. The unsaturation FAs degree was reduced. The dynamics of the adaptive response revealed a decrease in fluidity 20 min after the addition of PEG, indicating that the PEG has a fluidizing effect on the hydrophobic region of the cell membrane. Fluidity returned to initial values after 60 min of PEG exposure. Azospirillum brasilense is able to perceive osmotic changes by changing the membrane fluidity. This effect is offset by changes in the composition of membrane phospholipid and FA, contributing to the homeostasis of membrane fluidity under water deficit. This knowledge can be used to develop new Azospirillum brasilense formulations showing an adapted membrane to water deficit. © 2015 The Society for Applied Microbiology.

  18. Mitigation of salt stress in white clover (Trifolium repens) by Azospirillum brasilense and its inoculation effect.

    Science.gov (United States)

    Khalid, Muhammad; Bilal, Muhammad; Hassani, Danial; Iqbal, Hafiz M N; Wang, Hang; Huang, Danfeng

    2017-12-01

    Salinity is one of the increasingly serious environmental problems worldwide for cultivating agricultural crops. The present study was aimed to ascertain the potential of beneficial soil bacterium Azospirillum brasilense to alleviate saline stress in Trifolium repens. Experimental plants (white clover) were grown from seeds and inoculated with or without A. brasilense bacterial strain supplemented with 0, 40, 80, or 120 mM NaCl into soil. The growth attributes including, shoot heights, root lengths, fresh and dry weights, leaf area and chlorophyll content were significantly enhanced in T. repens plants grown in A. brasilense inoculated soil than un-inoculated controls, particularly under elevated salinity conditions (40, 80 and 120 mM NaCl). Malondialdehyde content of leaf was recorded to be declined under saline conditions. Moreover, the K + /Na + ratio was also improved in bacterium-inoculated plants, since A. brasilense significantly reduced the root and shoot Na + level under high salty environment. Results revealed that soil inoculation with A. brasilense could significantly promote T. repens growth under both non-saline and saline environments, and this study might be extended to other vegetables and crops for the germination and growth enhancement.

  19. Evaluation of reference genes for gene expression analysis using quantitative RT-PCR in Azospirillum brasilense.

    Science.gov (United States)

    McMillan, Mary; Pereg, Lily

    2014-01-01

    Azospirillum brasilense is a nitrogen fixing bacterium that has been shown to have various beneficial effects on plant growth and yield. Under normal conditions A. brasilense exists in a motile flagellated form, which, under starvation or stress conditions, can undergo differentiation into an encapsulated, cyst-like form. Quantitative RT-PCR can be used to analyse changes in gene expression during this differentiation process. The accuracy of quantification of mRNA levels by qRT-PCR relies on the normalisation of data against stably expressed reference genes. No suitable set of reference genes has yet been described for A. brasilense. Here we evaluated the expression of ten candidate reference genes (16S rRNA, gapB, glyA, gyrA, proC, pykA, recA, recF, rpoD, and tpiA) in wild-type and mutant A. brasilense strains under different culture conditions, including conditions that induce differentiation. Analysis with the software programs BestKeeper, NormFinder and GeNorm indicated that gyrA, glyA and recA are the most stably expressed reference genes in A. brasilense. The results also suggested that the use of two reference genes (gyrA and glyA) is sufficient for effective normalisation of qRT-PCR data.

  20. (Methyl)ammonium Transport in the Nitrogen-Fixing Bacterium Azospirillum brasilense

    Science.gov (United States)

    Van Dommelen, Anne; Keijers, Veerle; Vanderleyden, Jos; de Zamaroczy, Miklos

    1998-01-01

    An ammonium transporter of Azospirillum brasilense was characterized. In contrast to most previously reported putative prokaryotic NH4+ transporter genes, A. brasilense amtB is not part of an operon with glnB or glnZ which, in A. brasilense, encode nitrogen regulatory proteins PII and PZ, respectively. Sequence analysis predicts the presence of 12 transmembrane domains in the deduced AmtB protein and classifies AmtB as an integral membrane protein. Nitrogen regulates the transcription of the amtB gene in A. brasilense by the Ntr system. amtB is the first gene identified in A. brasilense whose expression is regulated by NtrC. The observation that ammonium uptake is still possible in mutants lacking the AmtB protein suggests the presence of a second NH4+ transport mechanism. Growth of amtB mutants at low ammonium concentrations is reduced compared to that of the wild type. This suggests that AmtB has a role in scavenging ammonium at low concentrations. PMID:9573149

  1. Evaluation of reference genes for gene expression analysis using quantitative RT-PCR in Azospirillum brasilense.

    Directory of Open Access Journals (Sweden)

    Mary McMillan

    Full Text Available Azospirillum brasilense is a nitrogen fixing bacterium that has been shown to have various beneficial effects on plant growth and yield. Under normal conditions A. brasilense exists in a motile flagellated form, which, under starvation or stress conditions, can undergo differentiation into an encapsulated, cyst-like form. Quantitative RT-PCR can be used to analyse changes in gene expression during this differentiation process. The accuracy of quantification of mRNA levels by qRT-PCR relies on the normalisation of data against stably expressed reference genes. No suitable set of reference genes has yet been described for A. brasilense. Here we evaluated the expression of ten candidate reference genes (16S rRNA, gapB, glyA, gyrA, proC, pykA, recA, recF, rpoD, and tpiA in wild-type and mutant A. brasilense strains under different culture conditions, including conditions that induce differentiation. Analysis with the software programs BestKeeper, NormFinder and GeNorm indicated that gyrA, glyA and recA are the most stably expressed reference genes in A. brasilense. The results also suggested that the use of two reference genes (gyrA and glyA is sufficient for effective normalisation of qRT-PCR data.

  2. Reduction of selenite by Azospirillum brasilense with the formation of selenium nanoparticles.

    Science.gov (United States)

    Tugarova, Anna V; Vetchinkina, Elena P; Loshchinina, Ekaterina A; Burov, Andrei M; Nikitina, Valentina E; Kamnev, Alexander A

    2014-10-01

    The ability to reduce selenite (SeO(3)(2-)) ions with the formation of selenium nanoparticles was demonstrated in Azospirillum brasilense for the first time. The influence of selenite ions on the growth of A. brasilense Sp7 and Sp245, two widely studied wild-type strains, was investigated. Growth of cultures on both liquid and solid (2 % agar) media in the presence of SeO(3)(2-) was found to be accompanied by the appearance of the typical red colouration. By means of transmission electron microscopy (TEM), electron energy loss spectroscopy (EELS) and X-ray fluorescence analysis (XFA), intracellular accumulation of elementary selenium in the form of nanoparticles (50 to 400 nm in diameter) was demonstrated for both strains. The proposed mechanism of selenite-to-selenium (0) reduction could involve SeO(3)(2-) in the denitrification process, which has been well studied in azospirilla, rather than a selenite detoxification strategy. The results obtained point to the possibility of using Azospirillum strains as endophytic or rhizospheric bacteria to assist phytoremediation of, and cereal cultivation on, selenium-contaminated soils. The ability of A. brasilense to synthesise selenium nanoparticles may be of interest to nanobiotechnology for "green synthesis" of bioavailable amorphous red selenium nanostructures.

  3. Preparation of miniantibodies to Azospirillum brasilense Sp245 surface antigens and their use for bacterial detection.

    Science.gov (United States)

    Dykman, Lev A; Staroverov, Sergei A; Guliy, Olga I; Ignatov, Oleg V; Fomin, Alexander S; Vidyasheva, Irina V; Karavaeva, Olga A; Bunin, Viktor D; Burygin, Gennady L

    2012-01-01

    This article reports the first preparation of miniantibodies to Azospirillum brasilense Sp245 surface antigens by using a combinatorial phage library of sheep antibodies. The prepared phage antibodies were used for the first time for lipopolysaccharide and flagellin detection by dot assay, electro-optical analysis of cell suspensions, and transmission electron microscopy. Interaction of A. brasilense Sp245 with antilipopolysaccharide and antiflagellin phage-displayed miniantibodies caused the magnitude of the electro-optical signal to change considerably. The electro-optical results were in good agreement with the electron microscopic data. This is the first reported possibility of employing phage-displayed miniantibodies in bacterial detection aided by electro-optical analysis of cell suspensions.

  4. Structure of the polysaccharides from the lipopolysaccharide of Azospirillum brasilense Jm125A2.

    Science.gov (United States)

    Sigida, Elena N; Fedonenko, Yuliya P; Shashkov, Alexander S; Zdorovenko, Evelina L; Konnova, Svetlana A; Ignatov, Vladimir V; Knirel, Yuriy A

    2015-10-30

    Two polysaccharides were obtained by mild acid degradation of the lipopolysaccharide of associative nitrogen-fixing bacteria Azospirillum brasilense Jm125A2 isolated from the rhizosphere of a pearl millet. The following structures of the polysaccharides were established by sugar and methylation analyses, Smith degradation, and (1)H and (13)C NMR spectroscopy: [Formula: see text] Structure 1 has been reported earlier for a polysaccharide from A. brasilense S17 (Fedonenko YP, Konnova ON, Zdorovenko EL, Konnova SA, Zatonsky GV, Shaskov AS, Ignatov VV, Knirel YA. Carbohydr Res 2008;343:810-6), whereas to our knowledge structure 2 has not been hitherto found in bacterial polysaccharides. Copyright © 2015 Elsevier Ltd. All rights reserved.

  5. Rhizobial Inoculation, Alone or Coinoculated with Azospirillum brasilense, Promotes Growth of Wetland Rice

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    Leandro Hahn

    Full Text Available ABSTRACT Rhizobia and associative bacteria promote growth in rice plants (Oryza sativa L. through a series of mechanisms, but most studies on inoculation have been performed based on inoculation with these bacteria in a separate or singular manner. The objective of this study was to assess the efficiency of single/isolated inoculation and inoculation combined with symbiotic rhizobia from forage legume and with Azospirillum brasilense on promoting growth and the root colonization process in wetland rice. Two rhizobia among four isolates from a greenhouse and a laboratory experiment were selected that efficiently promoted seed germination and rice plant growth in a sterilized substrate and in soil. The two most efficient isolates (UFRGS Vp16 and UFRGS Lc348 were inoculated alone or in combination with a commercial product containing A. brasilense in two field experiments using two wetland rice cultivars over two growing seasons. In the field experiments, these isolates coinoculated with A. brasilense promoted larger increases in the agronomic variables of wetland rice compared to the control without inoculation. Confocal laser microscopy confirmed the presence of inoculated bacteria tagged with gfp (UFRGS Vp16, UFRGS Lc348, and A. brasilense colonizing the root surface of the rice seedlings, mainly in the root hairs and lateral roots.

  6. [Isolation and purification of Mn-peroxidase from Azospirillum brasilense Sp245].

    Science.gov (United States)

    Kupriashina, M A; Selivanov, N Iu; Nikitina, V E

    2012-01-01

    Homogenous Mn-peroxidase of a 26-fold purity grade was isolated from a culture of Azospirillum brasilense Sp245 cultivated on a medium containing 0.1 mM pyrocatechol. The molecular weight of the enzyme is 43 kD as revealed by electrophoresis in SDS-PAAG. It was shown that the use of pyrocatechol and 2,2'-azino-bis(3-ethylbenzotiazoline-6-sulfonate) at concentrations of 0.1 and I mM as inductors increased the Mn-peroxidase activity by a factor of 3.

  7. Increased acidification in the rhizosphere of cactus seedlings induced by Azospirillum brasilense

    Science.gov (United States)

    Carrillo, Angel; Li, Ching; Bashan, Yoav

    2002-08-01

    Acidification of the rhizosphere of cactus seedlings (giant cardon, Pachycereus pringlei) after inoculation with the plant growth-promoting bacterium Azospirillum brasilense Cd, in the presence or absence of ammonium and nitrate, was studied to understand how to increase growth of cardon seedlings in poor desert soils. While ammonium enhanced rhizosphere and liquid culture acidification, inoculation with the bacteria enhanced it further. On the other hand, nitrate increased pH of the rhizosphere, but combined with the bacterial inoculation, increase in pH was significantly smaller. Bacterial inoculation with ammonium enhanced plant growth.

  8. Effect of Azospirillum brasilense inoculation on urease activity in soil and gamma-sterilized soil

    International Nuclear Information System (INIS)

    Perotti, E.B.R.; Pidello, A.

    1999-01-01

    Azospirillum spp. is considered a PGPR (plant growth promoting rhyzobacteria) bacterium, besides this interest, there is little information about its effects on other functional microbial groups or on soil enzymes. In this paper, the impact that Azospirillum brasilense 7001 inoculation has on urease activity expression in a Typic Argiudoll was studied. Evolution of urease activity of soil and of gamma irradiation (25 KGy) sterilized soil, and the inoculated strain survival were tested. The relation between soil urease activity and soil NH 4 +-N was also determined. In γ-sterilized soil, urease activity of inoculated soil increased with time, showing significant differences with regard to the control soil without inoculum at day 15. In non-sterile soil, urease activity decreased during the studied period in all treatments; in inoculated soil, it showed higher or lower values than the control depending on sampling time. Azospirillum survival was important and different according to soil condition conditions. The negative relation between NH 4 +-N concentration and soil urease activity (r 2 = 0.62) was observed in inoculated soil. The role of the addition of autoclaved inoculum in the urease activity expression is discussed. The research proves that in both studied situations Azospirillum modified soil urease activity, and that the competition with native microorganisms and soil NH 4 +-N may affect this bacterium capacity. (author)

  9. Chemical soil attributes after wheat cropping under nitrogen fertilization and inoculation with Azospirillum brasilense

    Directory of Open Access Journals (Sweden)

    Fernando Shintate Galindo

    2017-05-01

    Full Text Available Azospirillum brasilense plays an important role in biological nitrogen fixation (BNF in grasses. However, further studies are needed to define how much mineral N can be applied while simultaneously maintaining BNF contribution and maximizing crop yield and to determine the impact of these practices on soil fertility. Thus, we aimed to investigate the effect of inoculation with A. brasilense, in conjunction with varying N doses and sources in a Cerrado soil, on soil chemical attributes after two years of irrigated wheat production. The experiment was initiated in Selvíria - MS under no-tillage production in an Oxisol in 2014 and 2015. The experimental design was a randomized block design with four replications, and treatments were arranged in a 2 x 5 x 2 factorial arrangement as follows: two N sources (urea and Super N - urea with inhibitor of the enzyme urease NBPT (N - (n-butyl thiophosphoric triamide, five N rates (0, 50, 100, 150 and 200 kg ha-1, and with or without seed inoculation with A. brasilense. The increase in N rates did not influence the chemical soil attributes. Super N acidified the soil more compared to urea. A. brasilense inoculation reduced the effect of soil acidification in intensive irrigated wheat cultivation; however, the base extraction was higher, resulting in a lower soil CEC after cultivation with inoculation. Therefore, the cultivation of wheat inoculated with A. brasilense was not harmful to soil fertility because it did not reduce the base saturation and organic matter content (P, K, Ca, Mg, and S.

  10. CRECIMIENTO DE Cedrela odorata L. BIOFERTILIZADA CON Rhizophagus intraradices y Azospirillum brasilense EN VIVERO

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    Juan F. Aguirre-Medina

    2014-01-01

    Full Text Available Cedrela odorata L. es una especie que se distingue por la calidad de su madera. El cedro esta - blecido en campo debe adaptarse a cambios en disponibilidad de recursos; la sobrevivivencia es mayor cuando el sistema radical se asocia con microorganismos que mejoran la nutrición y crecimiento. El objetivo del presente trabajo fue evaluar el efecto de Rhizophagus intraradi - ces y Azospirillum brasilense sobre el crecimiento de C. odorata y la capacidad de absorción de nitrógeno (N y fósforo (P. Las semillas de cedro se sembraron en macetas de acuerdo con los siguientes trata - mientos: testigo, fertilización 15 N -15 P -15 K , R. intraradices , A. brasilense , R. intraradices + A. brasilense , y R. intraradices + A. brasilense + fertilización 15 N -15 P -15 K . Las variables morfológicas y fisiológicas de rendimiento y la colonización radical se registraron cada 28 días, y los contenidos de N y P, al final del experimento (140 días. En general, R. intraradices promovió mayor crecimiento vegetal ( P ≤ 0.05 de los componentes morfológicos y fisiológicos del rendimiento. La altura máxima (97 cm se registró en las plantas con R. intraradices + A. brasilense + fertilización 15 N -15 P -15 K , representando 40 % más altura que el testigo. El N y P incrementaron con la inoculación de los microorganismos solos y combinados.

  11. Structural and functional peculiarities of the lipopolysaccharide of Azospirillum brasilense SR55, isolated from the roots of Triticum durum.

    Science.gov (United States)

    Boyko, Alevtina S; Konnova, Svetlana A; Fedonenko, Yulia P; Zdorovenko, Evelina L; Smol'kina, Olga N; Kachala, Vadim V; Ignatov, Vladimir V

    2011-10-20

    Azospirillum brasilense SR55, isolated from the rhizosphere of Triticum durum, was classified as serogroup II on the basis of serological tests. Such serogroup affiliation is uncharacteristic of wheat-associated Azospirillum species. The lipid A of A. brasilense SR55 lipopolysaccharide contained 3-hydroxytetradecanoic, 3-hydroxyhexadecanoic, hexadecanoic and octadecenoic fatty acids. The structure of the lipopolysaccharide's O polysaccharide was established, with the branched octasaccharide repeating unit being represented by l-rhamnose, l-3-O-Me-rhamnose, d-galactose and d-glucuronic acid. The SR55 lipopolysaccharide induced deformations of wheat root hairs. The lipopolysaccharide was not involved in bacterial cell aggregation, but its use to pretreat wheat roots was conducive to cell adsorption. This study shows that Azospirillum bacteria can utilise their own lipopolysaccharide as a carbon source, which may give them an advantage in competitive natural environments. Copyright © 2011 Elsevier GmbH. All rights reserved.

  12. Intercropping Urochloa brizantha and sorghum inoculated with Azospirillum brasilense for silage

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    Allan Hisashi Nakao

    Full Text Available ABSTRACT Livestock performance in the Brazilian Cerrado has been limited by the low availability of good quality fodder, especially during periods of low rainfall. The aim of this study was to evaluate growth and dry matter production in two cultivars of sorghum, inoculated or not with diazotrophic bacteria, and as a monocrop or intercropped with palisade grass under a system of crop-livestock integration. The experiments were carried out in the field in the Cerrado region during the autumn-winter period of 2015 and 2016, on the experimental farm of the Faculty of Engineering at Ilha Solteira, UNESP, in Selvíria, in the State of Mato Groso do Sul, Brazil (MS. A randomised complete block experimental design was used in a 2 x 2 x 2 factorial scheme with four replications. The treatments corresponded to two agricultural years (2015 and 2016; the cultivation of dual-purpose grain sorghum, alone or intercropped with palisade grass; with or without inoculation of the sorghum seeds with the bacterium Azospirillum brasilense. The dry matter production of the plant components and plant growth were evaluated for the preparation of silage. Inoculation of sorghum seeds with the bacterium Azospirillum brasilense increases the production of plant dry matter for silage, irrespective of the cultivar or intercrop. Dual-purpose grain sorghum intercropped with palisade grass is a viable agronomic system for producing plant matter for silage during the autumn season.

  13. Insights into the 1.59-Mbp largest plasmid of Azospirillum brasilense CBG497.

    Science.gov (United States)

    Acosta-Cruz, Erika; Wisniewski-Dyé, Florence; Rouy, Zoé; Barbe, Valérie; Valdés, María; Mavingui, Patrick

    2012-09-01

    The plant growth-promoting proteobacterium Azospirillum brasilense enhances growth of many economically important crops, such as wheat, maize, and rice. The sequencing and annotation of the 1.59-Mbp replicon of A. brasilense CBG497, a strain isolated from a maize rhizosphere grown on an alkaline soil in the northeast of Mexico, revealed a GC content of 68.7 % and the presence of 1,430 potential protein-encoding genes, 1,147 of them classified into clusters of orthologous groups categories, and 16 tRNA genes representing 11 tRNA species. The presence of sixty-two genes representatives of the minimal gene set and chromid core genes suggests its importance in bacterial survival. The phaAB → G operon, reported as involved in the bacterial adaptation to alkaline pH in the presence of K(+), was also found on this replicon and detected in several Azospirillum strains. Phylogenetic analysis suggests that it was laterally acquired. We were not able to show its inference on the adaptation to basic pH, giving a hint about the presence of an alternative system for adaptation to alkaline pH.

  14. Doses and application methods of Azospirillum brasilense in irrigated upland rice

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    Nayara F. S. Garcia

    Full Text Available ABSTRACT The study was carried out in Selvíria-MS, in the 2011/12 and 2012/13 agricultural years, aiming to evaluate the efficiency of Azospirillum brasilense in nitrogen fixation in upland rice, as a function of doses and application methods of the inoculant containing this diazotrophic bacterium. The experimental design was randomized blocks, arranged in a 4 x 4 factorial scheme, with 4 doses of inoculant (control without inoculation, 100, 200 and 300 mL of the commercial product ha-1 and 4 application methods (seed inoculation, application in the sowing furrow, soil spraying after sowing, and foliar spraying at the beginning of plant tillering, with 4 replicates. During the experiment, the agronomic characteristics, production components and yield of the rice crop were evaluated. It was concluded that the inoculant containing Azospirillum brasilense promotes increase (19% in the yield of upland rice under sprinkler irrigation when used at the dose of 200 mL ha-1, regardless of the application methods.

  15. Growth and yield of corn hybrids in response to association with Azospirillum brasilense and nitrogen fertilization

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    Deniele Marini

    2015-02-01

    Full Text Available There is a growing interest in optimizing the positive effects of the association between Azospirillum bacteria and corn crop in order to reduce the use of nitrogen fertilizers. This study aimed to evaluate the inoculation efficiency of an A. brasilense-based commercial product in association with different rates of nitrogen fertilization in two corn genotypes. The experiment was arranged in a 2 x 2 x 5 factorial randomized block design, with four replications. The treatments consisted of two corn hybrids (30F53 and CD386; with and without inoculation with a commercial product based on A. brasilense and five nitrogen rates (0, 40, 80, 120 and 160 kg ha-1. The variables plant height, basal stem diameter, leaf area, shoot dry matter, leaf nitrogen content, length and diameter of the cob, weight of 100 grains and grain yield were evaluated. Inoculation with A. brasilense provided increases of 11 and 12% in leaf area and shoot dry matter, respectively. There were differences in the response of the corn hybrids for most variables and the increase in nitrogen supply provided increments in the growth and yield of corn.

  16. Components of corn crop yield under inoculation with Azospirillum brasilense using integrated crop-livestock system

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    Marcos da Silva Brum

    2016-09-01

    Full Text Available The objective of this study was to evaluate the agronomic characteristics of corn seed inoculated with Azospirillum brasilense, grown on black oat and ryegrass straw, and managed under different grazing strategies and doses of nitrogen. The experiment was conducted in Santa Maria, Rio Grande do Sul State, Brazil, during two agricultural seasons (2012/2013 and 2013/2014 in a randomized, complete block design with three replications. In the winter period, black oat and ryegrass straw were managed at different grazing heights by sheep (0.30, 0.20, 0.10 m, conventional grazing, and no grazing with three doses of nitrogen (0, 50, and 100 kg ha-1, with or without inoculation by A. brasilense. We used the hybrid Pioneer (P1630H® in 2012 and the hybrid Agroeste (AS 1551® in 2013. The height of corn plants was greater when they were grown on black oat and ryegrass straw, and the absence of grazing favored productivity. Under drought conditions, the application of nitrogen to the pasture favored corn development, increasing plant height, ear height, and stem diameter. Inoculation with A. brasilense had a positive effect on the characteristics of yield and productivity of corn, independent of growing season and hybrid used.

  17. Expressed sequence tags related to nitrogen metabolism in maize inoculated with Azospirillum brasilense.

    Science.gov (United States)

    Pereira-Defilippi, L; Pereira, E M; Silva, F M; Moro, G V

    2017-05-31

    The relative quantitative real-time expression of two expressed sequence tags (ESTs) codifying for key enzymes in nitrogen metabolism in maize, nitrate reductase (ZmNR), and glutamine synthetase (ZmGln1-3) was performed for genotypes inoculated with Azospirillum brasilense. Two commercial single-cross hybrids (AG7098 and 2B707) and two experimental synthetic varieties (V2 and V4) were raised under controlled greenhouse conditions, in six treatment groups corresponding to different forms of inoculation and different levels of nitrogen application by top-dressing. The genotypes presented distinct responses to inoculation with A. brasilense. Increases in the expression of ZmNR were observed for the hybrids, while V4 only displayed a greater level of expression when the plants received nitrogenous fertilization by top-dressing and there was no inoculation. The expression of the ZmGln1-3EST was induced by A. brasilense in the hybrids and the variety V4. In contrast, the variety V2 did not respond to inoculation.

  18. Cellular responses during morphological transformation in Azospirillum brasilense and Its flcA knockout mutant.

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    Xingsheng Hou

    Full Text Available FlcA is a response regulator controlling flocculation and the morphological transformation of Azospirillum cells from vegetative to cyst-like forms. To understand the cellular responses of Azospirillum to conditions that cause morphological transformation, proteins differentially expressed under flocculation conditions in A. brasilense Sp7 and its flcA knockout mutant were investigated. Comparison of 2-DE protein profiles of wild-type (Sp7 and a flcA deletion mutant (Sp7-flcAΔ revealed a total of 33 differentially expressed 2-DE gel spots, with 22 of these spots confidently separated to allow protein identification. Analysis of these spots by liquid chromatography-tandem mass spectrometry (LC-MS/MS and MASCOT database searching identified 48 proteins (≥10% emPAI in each spot. The functional characteristics of these proteins included carbon metabolism (beta-ketothiolase and citrate synthase, nitrogen metabolism (Glutamine synthetase and nitric oxide synthase, stress tolerance (superoxide dismutase, Alkyl hydroperoxidase and ATP-dependent Clp protease proteolytic subunit and morphological transformation (transducer coupling protein. The observed differences between Sp7 wild-type and flcA- strains enhance our understanding of the morphological transformation process and help to explain previous phenotypical observations. This work is a step forward in connecting the Azospirillum phenome and genome.

  19. Cellular responses during morphological transformation in Azospirillum brasilense and Its flcA knockout mutant.

    Science.gov (United States)

    Hou, Xingsheng; McMillan, Mary; Coumans, Joëlle V F; Poljak, Anne; Raftery, Mark J; Pereg, Lily

    2014-01-01

    FlcA is a response regulator controlling flocculation and the morphological transformation of Azospirillum cells from vegetative to cyst-like forms. To understand the cellular responses of Azospirillum to conditions that cause morphological transformation, proteins differentially expressed under flocculation conditions in A. brasilense Sp7 and its flcA knockout mutant were investigated. Comparison of 2-DE protein profiles of wild-type (Sp7) and a flcA deletion mutant (Sp7-flcAΔ) revealed a total of 33 differentially expressed 2-DE gel spots, with 22 of these spots confidently separated to allow protein identification. Analysis of these spots by liquid chromatography-tandem mass spectrometry (LC-MS/MS) and MASCOT database searching identified 48 proteins (≥10% emPAI in each spot). The functional characteristics of these proteins included carbon metabolism (beta-ketothiolase and citrate synthase), nitrogen metabolism (Glutamine synthetase and nitric oxide synthase), stress tolerance (superoxide dismutase, Alkyl hydroperoxidase and ATP-dependent Clp protease proteolytic subunit) and morphological transformation (transducer coupling protein). The observed differences between Sp7 wild-type and flcA- strains enhance our understanding of the morphological transformation process and help to explain previous phenotypical observations. This work is a step forward in connecting the Azospirillum phenome and genome.

  20. Mutational analysis of GlnB residues critical for NifA activation in Azospirillum brasilense.

    Science.gov (United States)

    Inaba, Juliana; Thornton, Jeremy; Huergo, Luciano Fernandes; Monteiro, Rose Adele; Klassen, Giseli; Pedrosa, Fábio de Oliveira; Merrick, Mike; de Souza, Emanuel Maltempi

    2015-02-01

    PII proteins are signal transduction that sense cellular nitrogen status and relay this signals to other targets. Azospirillum brasilense is a nitrogen fixing bacterium, which associates with grasses and cereals promoting beneficial effects on plant growth and crop yields. A. brasilense contains two PII encoding genes, named glnB and glnZ. In this paper, glnB was mutagenised in order to identify amino acid residues involved in GlnB signaling. Two variants were obtained by random mutagenesis, GlnBL13P and GlnBV100A and a site directed mutant, GlnBY51F, was obtained. Their ability to complement nitrogenase activity of glnB mutant strains of A. brasilense were determined. The variant proteins were also overexpressed in Escherichia coli, purified and characterized biochemically. None of the GlnB variant forms was able to restore nitrogenase activity in glnB mutant strains of A. brasilense LFH3 and 7628. The purified GlnBY51F and GlnBL13P proteins could not be uridylylated by GlnD, whereas GlnBV100A was uridylylated but at only 20% of the rate for wild type GlnB. Biochemical and computational analyses suggest that residue Leu13, located in the α helix 1 of GlnB, is important to maintain GlnB trimeric structure and function. The substitution V100A led to a lower affinity for ATP binding. Together the results suggest that NifA activation requires uridylylated GlnB bound to ATP. Copyright © 2014 Elsevier GmbH. All rights reserved.

  1. Residual phosphate fertilization and Azospirillum brasilense in the common bean in succession to maize intercropped with Marandu grass

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    Lourdes Dickmann

    Full Text Available ABSTRACT One of the alternatives for achieving sustainable agriculture and a reduction in production costs, especially with phosphate fertilisers, is to inoculate seeds with bacteria of the genus Azospirillum. The aim of this study therefore, was to evaluate residual phosphate fertilisation and Azospirillum brasilense, together with the contribution of straw from maize intercropped with Marandu grass, on leaf nutritional content, yield components and winter bean yield. The experiment was carried out on the Teaching and Research Farm, of the School of Engineering at UNESP, located in Selvíria in the State of Mato Grosso do Sul, in a typic clayey dystrophic Red Latosol. The experimental design was of randomised blocks with four replications in a 5 x 2 factorial scheme. The treatments consisted of beans sown on straw from maize intercropped with Marandu grass on areas that had received five levels of P2O5 in the form of MAP, applied during an initial cultivation of black oats (0, 30, 60, 120 and 240 kg ha-1, both with and without inoculation of the oat and maize which preceded the beans with Azospirillum brasilense. Leaf nutrient content, leaf chlorophyll index (ICF, yield components and bean productivity were all evaluated. Inoculation with Azospirillum brasilense of the black oat and maize seeds improved the nutritional status of the plants, but had a negative effect on grain yield. Fertilisation of the oat crop with phosphorus had a positive residual effect on the beans, with increases in yield components and grain yield.

  2. The role of the antimicrobial compound 2,4-diacetylphloroglucinol in the impact of biocontrol Pseudomonas fluorescens F113 on Azospirillum brasilense phytostimulators.

    Science.gov (United States)

    Couillerot, Olivier; Combes-Meynet, Emeline; Pothier, Joël F; Bellvert, Floriant; Challita, Elita; Poirier, Marie-Andrée; Rohr, René; Comte, Gilles; Moënne-Loccoz, Yvan; Prigent-Combaret, Claire

    2011-06-01

    Pseudomonads producing the antimicrobial metabolite 2,4-diacetylphloroglucinol (Phl) can control soil-borne phytopathogens, but their impact on other plant-beneficial bacteria remains poorly documented. Here, the effects of synthetic Phl and Phl(+) Pseudomonas fluorescens F113 on Azospirillum brasilense phytostimulators were investigated. Most A. brasilense strains were moderately sensitive to Phl. In vitro, Phl induced accumulation of carotenoids and poly-β-hydroxybutyrate-like granules, cytoplasmic membrane damage and growth inhibition in A. brasilense Cd. Experiments with P. fluorescens F113 and a Phl(-) mutant indicated that Phl production ability contributed to in vitro growth inhibition of A. brasilense Cd and Sp245. Under gnotobiotic conditions, each of the three strains, P. fluorescens F113 and A. brasilense Cd and Sp245, stimulated wheat growth. Co-inoculation of A. brasilense Sp245 and Pseudomonas resulted in the same level of phytostimulation as in single inoculations, whereas it abolished phytostimulation when A. brasilense Cd was used. Pseudomonas Phl production ability resulted in lower Azospirillum cell numbers per root system (based on colony counts) and restricted microscale root colonization of neighbouring Azospirillum cells (based on confocal microscopy), regardless of the A. brasilense strain used. Therefore, this work establishes that Phl(+) pseudomonads have the potential to interfere with A. brasilense phytostimulators on roots and with their plant growth promotion capacity.

  3. Co2 + interaction with Azospirillum brasilense Sp7 cells: a 57Co emission Mössbauer spectroscopic study

    Science.gov (United States)

    Kamnev, Alexander A.; Tugarova, Anna V.; Biró, Borbála; Kovács, Krisztina; Homonnay, Zoltán; Kuzmann, Ernő; Vértes, Attila

    2012-03-01

    Preliminary 57Co emission Mössbauer spectroscopic data were obtained for the soil bacterium Azospirillum brasilense Sp7 ( T = 80 K) in frozen 57Co2 + -containing suspensions and in their dried residues. The Mössbauer parameters were compared with those for A. brasilense strain Sp245 differing from strain Sp7 by ecological behaviour. Live cells of both strains showed metabolic transformations of 57Co2 + within an hour. Differences in the parameters observed for the two strains under similar conditions suggest dissimilarities in their metabolic response to Co2 + .

  4. Co{sup 2 + } interaction with Azospirillum brasilense Sp7 cells: a {sup 57}Co emission Moessbauer spectroscopic study

    Energy Technology Data Exchange (ETDEWEB)

    Kamnev, Alexander A.; Tugarova, Anna V. [Russian Academy of Sciences, Institute of Biochemistry and Physiology of Plants and Microorganisms (Russian Federation); Biro, Borbala [Hungarian Academy of Sciences, Research Institute for Soil Science and Agricultural Chemistry (Hungary); Kovacs, Krisztina, E-mail: kkriszti@chem.elte.hu; Homonnay, Zoltan; Kuzmann, Erno; Vertes, Attila [Eoetvoes Lorand University, Institute of Chemistry (Hungary)

    2012-03-15

    Preliminary {sup 57}Co emission Moessbauer spectroscopic data were obtained for the soil bacterium Azospirillum brasilense Sp7 (T = 80 K) in frozen {sup 57}Co{sup 2 + }-containing suspensions and in their dried residues. The Moessbauer parameters were compared with those for A. brasilense strain Sp245 differing from strain Sp7 by ecological behaviour. Live cells of both strains showed metabolic transformations of {sup 57}Co{sup 2 + } within an hour. Differences in the parameters observed for the two strains under similar conditions suggest dissimilarities in their metabolic response to Co{sup 2 + }.

  5. Genome Sequence of Azospirillum brasilense CBG497 and Comparative Analyses of Azospirillum Core and Accessory Genomes provide Insight into Niche Adaptation

    Science.gov (United States)

    Wisniewski-Dyé, Florence; Lozano, Luis; Acosta-Cruz, Erika; Borland, Stéphanie; Drogue, Benoît; Prigent-Combaret, Claire; Rouy, Zoé; Barbe, Valérie; Mendoza Herrera, Alberto; González, Victor; Mavingui, Patrick

    2012-01-01

    Bacteria of the genus Azospirillum colonize roots of important cereals and grasses, and promote plant growth by several mechanisms, notably phytohormone synthesis. The genomes of several Azospirillum strains belonging to different species, isolated from various host plants and locations, were recently sequenced and published. In this study, an additional genome of an A. brasilense strain, isolated from maize grown on an alkaline soil in the northeast of Mexico, strain CBG497, was obtained. Comparative genomic analyses were performed on this new genome and three other genomes (A. brasilense Sp245, A. lipoferum 4B and Azospirillum sp. B510). The Azospirillum core genome was established and consists of 2,328 proteins, representing between 30% to 38% of the total encoded proteins within a genome. It is mainly chromosomally-encoded and contains 74% of genes of ancestral origin shared with some aquatic relatives. The non-ancestral part of the core genome is enriched in genes involved in signal transduction, in transport and in metabolism of carbohydrates and amino-acids, and in surface properties features linked to adaptation in fluctuating environments, such as soil and rhizosphere. Many genes involved in colonization of plant roots, plant-growth promotion (such as those involved in phytohormone biosynthesis), and properties involved in rhizosphere adaptation (such as catabolism of phenolic compounds, uptake of iron) are restricted to a particular strain and/or species, strongly suggesting niche-specific adaptation. PMID:24705077

  6. Genome Sequence of Azospirillum brasilense CBG497 and Comparative Analyses of Azospirillum Core and Accessory Genomes provide Insight into Niche Adaptation

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    Victor González

    2012-09-01

    Full Text Available Bacteria of the genus Azospirillum colonize roots of important cereals and grasses, and promote plant growth by several mechanisms, notably phytohormone synthesis. The genomes of several Azospirillum strains belonging to different species, isolated from various host plants and locations, were recently sequenced and published. In this study, an additional genome of an A. brasilense strain, isolated from maize grown on an alkaline soil in the northeast of Mexico, strain CBG497, was obtained. Comparative genomic analyses were performed on this new genome and three other genomes (A. brasilense Sp245, A. lipoferum 4B and Azospirillum sp. B510. The Azospirillum core genome was established and consists of 2,328 proteins, representing between 30% to 38% of the total encoded proteins within a genome. It is mainly chromosomally-encoded and contains 74% of genes of ancestral origin shared with some aquatic relatives. The non-ancestral part of the core genome is enriched in genes involved in signal transduction, in transport and in metabolism of carbohydrates and amino-acids, and in surface properties features linked to adaptation in fluctuating environments, such as soil and rhizosphere. Many genes involved in colonization of plant roots, plant-growth promotion (such as those involved in phytohormone biosynthesis, and properties involved in rhizosphere adaptation (such as catabolism of phenolic compounds, uptake of iron are restricted to a particular strain and/or species, strongly suggesting niche-specific adaptation.

  7. Azospirillum brasilense and Azospirillum lipoferum Hydrolyze Conjugates of GA20 and Metabolize the Resultant Aglycones to GA1 in Seedlings of Rice Dwarf Mutants1

    Science.gov (United States)

    Cassán, Fabricio; Bottini, Rubén; Schneider, Gernot; Piccoli, Patricia

    2001-01-01

    Azospirillum species are plant growth-promotive bacteria whose beneficial effects have been postulated to be partially due to production of phytohormones, including gibberellins (GAs). In this work, Azospirillum brasilense strain Cd and Azospirillum lipoferum strain USA 5b promoted sheath elongation growth of two single gene GA-deficient dwarf rice (Oryza sativa) mutants, dy and dx, when the inoculated seedlings were supplied with [17,17-2H2]GA20-glucosyl ester or [17,17- 2H2]GA20-glucosyl ether. Results of capillary gas chromatography-mass spectrometry analysis show that this growth was due primarily to release of the aglycone [17,17-2H2]GA20 and its subsequent 3β-hydroxylation to [17,17-2H2]GA1 by the microorganism for the dy mutant, and by both the rice plant and microorganism for the dx mutant. PMID:11299384

  8. Crecimiento de Azospirillum brasilense en presencia de disacáridos: sacarosa y lactosa

    OpenAIRE

    Yudyt Díaz-Saez; Manuel Díaz-de los Ríos; Mario Alberto-Casas; Arianna Nuñez-Caraballo; Marlene Martínez-Mora

    2013-01-01

    La obtención de biopolímeros a partir de fermentaciones bacterianas requiere de la selección adecuada de las condiciones del proceso. Se evaluó el crecimiento de la cepa Azospirillum brasilense 8-INICA en medio líquido suplementado con disacáridos. Las mediciones se realizaron a las 23 h de incubación con la determinación de la densidad óptica, la concentración de azúcares reductores y concentración de carbohidratos totales, así como la determinación del pH del sobrenadante. Se confirmó el má...

  9. Effect of seed inoculation with Azospirillum brasilense and nitrogen fertilization rates on maize plant yield and silage quality

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    Fernando Reimann Skonieski

    Full Text Available ABSTRACT The objective of this study was to determine the effect of Azospirillum brasilense inoculation and different nitrogen (N rates applied as topdressing on the productivity of a maize crop and the nutritional value of maize silage. Two experiments were conducted in the 2012/2013 and 2013/2014 harvests. Treatments were distributed in a randomized block design in a factorial arrangement, which consisted of two maize hybrids (AS 1572 and Defender coupled with nitrogen rates (0, 60, 120, 240, and 480 kg ha-1, inoculated or uninoculated with A. brasilense. Inoculated seeds were treated with the A. brasilense strains Ab-V5 and Ab-V6. Inoculation with A. brasilense showed interaction with the hybrids, agricultural years, and nitrogen rates for the maize plant yield. In the 2012/2013 agricultural year, inoculation increased the AS 1572 hybrid silage yield by 6.16% and, in the 2013/2014 harvest, A. brasilense inoculation produced an increase of 16.15% for the Defender hybrid. Nitrogen fertilization applied at 0, 60, and 120 kg ha-1 N benefited the plants inoculated with A. brasilense. The statistical equations revealed that N rates between 0 and 184 kg ha-1 in A. brasilense inoculated plants raised the plant productivity for silage when compared with the control plants. Regarding the nutritional value of the silage, inoculation with A. brasilense increased the ether extract levels and total digestible nutrients and reduced the amount of acid detergent fiber. For all this, positive results with inoculation for silage yield are dependent on nitrogen fertilization rate. Inoculation with A. brasilense can promote changes in the maize silage quality, but with obtained results it is not possible to definitely conclude upon nutritive value of maize silage.

  10. Tiller density and tillering on Brachiaria brizantha cv. Marandu pastures inoculated with Azospirillum brasilense

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    B.C. Pedreira

    Full Text Available ABSTRACT The objective of this study is to verify the population density and the dynamics of tillering in the Marandu palisade grass sward subjected to nitrogen (N fertilization strategies, characterized by the N supply via urea or bacterial inoculant (Azospirillum brasilense. The treatments comprised of four nitrogen fertilization strategies: (A Without fertilization, (B 80 kg N/ha, (C inoculant (A. brasilense, and (D 80 kg N/ha + inoculant, distributed in a randomized complete block design, with three replications. The nitrogen supply strategies were evaluated during six periods: October, November, and December (2012 as well as January, March, and April (2013. The nitrogen dose or inoculant had no effect on the tiller appearance rate (TAR, tiller mortality rate (TMR, tiller survival rate (TSR, or tiller population density (TPD. However, these variables were influenced by the season. The TAR and TSR were higher at the beginning of the experimental period (October and lower towards the end of the period (March-April, whereas, TMR and TPD exhibited the opposite behavior, with lower values in October and higher from January onward. Neither the nitrogen nor the inoculant influenced the population dynamics of the tillers in Marandu palisade grass.

  11. Co-inoculation of Azospirillum brasilense and Herbaspirillum seropedicae in maize

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    Janaína Dartora

    2016-06-01

    Full Text Available ABSTRACT Bacteria from the genera Azospirillum and Herbaspirillum have been associated with increments in maize yield. The aim of this study was to evaluate the maize yield and nutritional content in response to inoculation with A. brasilense and H. seropediceae in association with nitrogen (N fertilization. The experimental design was randomized blocks in a 4 x 5 factorial scheme, with four replicates. The treatments consisted of seed inoculation (control without N and inoculation, A. brasilense strain - AbV5, H. seropediceae strain - SMR1 and co-inoculation AbV5 + SMR1 and N doses (0, 40, 80, 120 and 160 kg ha-1. The following variables were evaluated: ear insertion height, ear length, ear diameter, number of rows per ear, number of grains per row, ear weight, yield and NPK contents in leaves and grains. There was no interaction between the factors studied. Co-inoculation with the strains promoted increments of 12% in leaf P content, compared with control, and N fertilization promoted increase in yield and leaf P content up to the maximum dose studied.

  12. Electro-optical study of the exposure of Azospirillum brasilense carbohydrate epitopes.

    Science.gov (United States)

    Guliy, Olga I; Matora, Larisa Yu; Dykman, Lev A; Staroverov, Sergey A; Burygin, Gennady L; Bunin, Viktor D; Burov, Andrei M; Ignatov, Oleg V

    2015-01-01

    The exposure of Azospirillum brasilense carbohydrate epitopes was investigated by electro-optical analysis of bacterial cell suspensions. To study changes in the electro-optical (EO) properties of the suspensions, we used antibodies generated to the complete lipopolysaccharide of A. brasilense type strain Sp7 and also antibodies to the smooth and rough O polysaccharides of Sp7. After 18 hr of culture growth, the EO signal of the suspension treated with antibodies to smooth O polysaccharide was approximately 20% lower than that of the suspension treated with antibodies to complete lipopolysaccharide (control). After 72 hr of culture growth, the strongest EO signal was observed for the cells treated with antibodies to rough O polysaccharide (approximately 46% greater than the control), whereas for the cells treated with antibodies to smooth O polysaccharide, it was much lower (approximately 23% of the control). These data were confirmed by electron microscopy. The results of the study may have importance for the rapid evaluation of changes in lipopolysaccharide form in microbial biotechnology, when the antigenic composition of the bacterial surface requires close control.

  13. Compatibility of Azospirillum brasilense and Pseudomonas fluorescens in growth promotion of groundnut ( Arachis hypogea L.).

    Science.gov (United States)

    Prasad, Andhare A; Babu, Subramanian

    2017-01-01

    We attempted to study the compatibility among plant beneficial bacteria in the culture level by growing them near in the nutrient agar plates. Among all the bacteria tested, Rhizobium was found to inhibit the growth of other bacteria. From the compatible group of PGPR, we have selected one biofertilizer (Azospirillum brasilense strain TNAU) and one biocontrol agent (Pseudomonas fluorescens strain PF1) for further studies in the pot culture. We have also developed a bioformulation which is talc powder based, for individual bacteria and mixed culture. This formulation was used as seed treatment, soil application, seedling root dip and foliar spray in groundnut crop in vitro germination conditions. A. brasilense was found to enhance the tap root growth and P. fluorescens, the lateral root growth. The other growth parameters like shoot growth, number of leaves were enhanced by the combination of both of the bacteria than their individual formulations. Among the method of application tested in our study, soil application was found to be the best in yielding better results of plant growth promotion.

  14. A hybrid two-component system protein from Azospirillum brasilense Sp7 was involved in chemotaxis.

    Science.gov (United States)

    Cui, Yanhua; Tu, Ran; Wu, Lixian; Hong, Yuanyuan; Chen, Sanfeng

    2011-09-20

    We here report the sequence and functional analysis of org35 of Azospirillum brasilense Sp7, which was originally identified to be able to interact with NifA in yeast-two-hybrid system. The org35 encodes a hybrid two-component system protein, including N-terminal PAS domains, a histidine kinase (HPK) domain and a response regulator (RR) domain in C-terminal. To determine the function of the Org35, a deletion-insertion mutant in PAS domain [named Sp7353] and a complemental strain Sp7353C were constructed. The mutant had reduced chemotaxis ability compared to that of wild-type, and the complemental strain was similar to the wild-type strain. These data suggested that the A. brasilense org35 played a key role in chemotaxis. Variants containing different domains of the org35 were expressed, and the functions of these domains were studied in vitro. Phosphorylation assays in vitro demonstrated that the HPK domain of Org35 possessed the autokinase activity and that the phosphorylated HPK was able to transfer phosphate groups to the RR domain. The result indicated Org35 was a phosphorylation-communicating protein. Copyright © 2010 Elsevier GmbH. All rights reserved.

  15. Compatibility of Azospirillum brasilense and Pseudomonas fluorescens in growth promotion of groundnut ( Arachis hypogea L.

    Directory of Open Access Journals (Sweden)

    ANDHARE A. PRASAD

    Full Text Available ABSTRACT We attempted to study the compatibility among plant beneficial bacteria in the culture level by growing them near in the nutrient agar plates. Among all the bacteria tested, Rhizobium was found to inhibit the growth of other bacteria. From the compatible group of PGPR, we have selected one biofertilizer (Azospirillum brasilense strain TNAU and one biocontrol agent (Pseudomonas fluorescens strain PF1 for further studies in the pot culture. We have also developed a bioformulation which is talc powder based, for individual bacteria and mixed culture. This formulation was used as seed treatment, soil application, seedling root dip and foliar spray in groundnut crop in vitro germination conditions. A. brasilense was found to enhance the tap root growth and P. fluorescens, the lateral root growth. The other growth parameters like shoot growth, number of leaves were enhanced by the combination of both of the bacteria than their individual formulations. Among the method of application tested in our study, soil application was found to be the best in yielding better results of plant growth promotion.

  16. Physiological and biochemical characterization of Azospirillum brasilense strains commonly used as plant growth-promoting rhizobacteria.

    Science.gov (United States)

    Di Salvo, Luciana P; Silva, Esdras; Teixeira, Kátia R S; Cote, Rosalba Esquivel; Pereyra, M Alejandra; García de Salamone, Inés E

    2014-12-01

    Azospirillum is a plant growth-promoting rhizobacteria (PGPR) genus vastly studied and utilized as agriculture inoculants. Isolation of new strains under different environmental conditions allows the access to the genetic diversity and improves the success of inoculation procedures. Historically, the isolation of this genus has been performed by the use of some traditional culture media. In this work we characterized the physiology and biochemistry of five different A. brasilense strains, commonly used as cereal inoculants. The aim of this work is to contribute to pose into revision some concepts concerning the most used protocols to isolate and characterize this bacterium. We characterized their growth in different traditional and non-traditional culture media, evaluated some PGPR mechanisms and characterized their profiles of fatty acid methyl esters and carbon-source utilization. This work shows, for the first time, differences in both profiles, and ACC deaminase activity of A. brasilense strains. Also, we show unexpected results obtained in some of the evaluated culture media. Results obtained here and an exhaustive knowledge revision revealed that it is not appropriate to conclude about bacterial species without analyzing several strains. Also, it is necessary to continue developing studies and laboratory techniques to improve the isolation and characterization protocols. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Nitric oxide metabolism and indole acetic acid biosynthesis cross-talk in Azospirillum brasilense SM.

    Science.gov (United States)

    Koul, Vatsala; Tripathi, Chandrakant; Adholeya, Alok; Kochar, Mandira

    2015-04-01

    Production of nitric oxide (NO) and the presence of NO metabolism genes, nitrous oxide reductase (nosZ), nitrous oxide reductase regulator (nosR) and nitric oxide reductase (norB) were identified in the plant-associated bacterium (PAB) Azospirillum brasilense SM. NO presence was confirmed in all overexpressing strains, while improvement in the plant growth response of these strains was mediated by increased NO and indole-3-acetic acid (IAA) levels in the strains. Electron microscopy showed random distribution to biofilm, with surface colonization of pleiomorphic Azospirilla. Quantitative IAA estimation highlighted a crucial role of nosR and norBC in regulating IAA biosynthesis. The NO quencher and donor reduced/blocked IAA biosynthesis by all strains, indicating their common regulatory role in IAA biosynthesis. Tryptophan (Trp) and l-Arginine (Arg) showed higher expression of NO genes tested, while in the case of ipdC, only Trp and IAA increased expression, while Arg had no significant effect. The highest nosR expression in SMnosR in the presence of IAA and Trp, along with its 2-fold IAA level, confirmed the relationship of nosR overexpression with Trp in increasing IAA. These results indicate a strong correlation between IAA and NO in A. brasilense SM and suggest the existence of cross-talk or shared signaling mechanisms in these two growth regulators. Copyright © 2015 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.

  18. [INFLUENCE OF AZOSPIRILLUM BRASILENSE 10/1 ON ASSOCIATIVE NITROGEN FIXATION AND INTRAVARIETAL POLYMORPHISM OF SPRING TRITICALE].

    Science.gov (United States)

    Patika, V P; Nadkernichna, O V; Shahovnina, O O

    2015-01-01

    It is shown, that the perspective Ukrainian sorts of spring triticale characterizes by considerable polymorphism by associative N2-fixing ability in root zone of plants. Application of active strain Azospirillum brasilense 10/1 promotes the decline of variability of this sign within the limits of sort, increase potential nitrogen activity is on the average in 3,2-4,7 times and also distributing normalizations in the selections of the inoculated plants.

  19. Azospirillum brasilense Chemotaxis Depends on Two Signaling Pathways Regulating Distinct Motility Parameters.

    Science.gov (United States)

    Mukherjee, Tanmoy; Kumar, Dhivya; Burriss, Nathan; Xie, Zhihong; Alexandre, Gladys

    2016-06-15

    The genomes of most motile bacteria encode two or more chemotaxis (Che) systems, but their functions have been characterized in only a few model systems. Azospirillum brasilense is a motile soil alphaproteobacterium able to colonize the rhizosphere of cereals. In response to an attractant, motile A. brasilense cells transiently increase swimming speed and suppress reversals. The Che1 chemotaxis pathway was previously shown to regulate changes in the swimming speed, but it has a minor role in chemotaxis and root surface colonization. Here, we show that a second chemotaxis system, named Che4, regulates the probability of swimming reversals and is the major signaling pathway for chemotaxis and wheat root surface colonization. Experimental evidence indicates that Che1 and Che4 are functionally linked to coordinate changes in the swimming motility pattern in response to attractants. The effect of Che1 on swimming speed is shown to enhance the aerotactic response of A. brasilense in gradients, likely providing the cells with a competitive advantage in the rhizosphere. Together, the results illustrate a novel mechanism by which motile bacteria utilize two chemotaxis pathways regulating distinct motility parameters to alter movement in gradients and enhance the chemotactic advantage. Chemotaxis provides motile bacteria with a competitive advantage in the colonization of diverse niches and is a function enriched in rhizosphere bacterial communities, with most species possessing at least two chemotaxis systems. Here, we identify the mechanism by which cells may derive a significant chemotactic advantage using two chemotaxis pathways that ultimately regulate distinct motility parameters. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

  20. Metabolic adaptations of Azospirillum brasilense to oxygen stress by cell-to-cell clumping and flocculation.

    Science.gov (United States)

    Bible, Amber N; Khalsa-Moyers, Gurusahai K; Mukherjee, Tanmoy; Green, Calvin S; Mishra, Priyanka; Purcell, Alicia; Aksenova, Anastasia; Hurst, Gregory B; Alexandre, Gladys

    2015-12-01

    The ability of bacteria to monitor their metabolism and adjust their behavior accordingly is critical to maintain competitiveness in the environment. The motile microaerophilic bacterium Azospirillum brasilense navigates oxygen gradients by aerotaxis in order to locate low oxygen concentrations that can support metabolism. When cells are exposed to elevated levels of oxygen in their surroundings, motile A. brasilense cells implement an alternative response to aerotaxis and form transient clumps by cell-to-cell interactions. Clumping was suggested to represent a behavior protecting motile cells from transiently elevated levels of aeration. Using the proteomics of wild-type and mutant strains affected in the extent of their clumping abilities, we show that cell-to-cell clumping represents a metabolic scavenging strategy that likely prepares the cells for further metabolic stresses. Analysis of mutants affected in carbon or nitrogen metabolism confirmed this assumption. The metabolic changes experienced as clumping progresses prime cells for flocculation, a morphological and metabolic shift of cells triggered under elevated-aeration conditions and nitrogen limitation. The analysis of various mutants during clumping and flocculation characterized an ordered set of changes in cell envelope properties accompanying the metabolic changes. These data also identify clumping and early flocculation to be behaviors compatible with the expression of nitrogen fixation genes, despite the elevated-aeration conditions. Cell-to-cell clumping may thus license diazotrophy to microaerophilic A. brasilense cells under elevated oxygen conditions and prime them for long-term survival via flocculation if metabolic stress persists. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

  1. Comparison of two Cellulomonas strains and their interaction with Azospirillum brasilense in degradation of wheat straw and associated nitrogen fixation

    Energy Technology Data Exchange (ETDEWEB)

    Halsall, D.M.; Gibson, A.H.

    1986-04-01

    A mutant strain of Cellulomonas sp. CS1-17 was compared with Cellulomonas gelida 2480 as the cellulolytic component of a mixed culture which was responsible for the breakdown of wheat straw to support asymbiotic nitrogen fixation by Azospirillum brasilense Sp7 (ATCC 29145). Cellulomonas sp. strain CS1-17 was more efficient than was C. gelida in cellulose breakdown at lower oxygen concentrations and, in mixed culture with A. brasilense, it supported higher nitrogenase activity(C/sub 2/H/sub 2/ reduction) and nitrogen fixation with straw as the carbon source. Based on gravimetric determinations of straw breakdown and total N determinations, the efficiency of nitrogen fixation was 72 and 63 mg of N per g of straw utilized for the mixtures containing Cellulomonas sp. and C. gelida, respectively. Both Cellulomonas spp. and Azospirillum spp. exhibited a wide range of pH tolerance. When introduced into sterilized soil, the Cellulomonas sp.-Azospirillum brasilense association was more effective in nitrogen fixation at a pH of 7.0 than at the native soil pH (5.6). This was also true of the indigenous diazotrophic microflora of this soil. The potential implications of this work to the field situation are discussed. 16 references.

  2. INFLUÊNCIA DO THIDIAZURON E DA INOCULAÇÃO COM Azospirillum brasilense NO CRESCIMENTO E PRODUTIVIDADE DO ARROZ DE TERRAS ALTAS / INFLUENCE OF THIDIAZURON AND INOCULATION WITH Azospirillum brasilense IN THE GROWTH AND PRODUCTIVITY OF HIGHLAND RICE

    Directory of Open Access Journals (Sweden)

    L. M. Garé

    2017-12-01

    Full Text Available A inoculação com bactérias do gênero Azospirillum pode contribuir com o fornecimento de nitrogênio (N e com o crescimento das plantas, pois esses microrganismos são também promotores de crescimento. Por outro lado a aplicação nas doses e épocas adequadas do regulador vegetal de efeito citocinínico thidiazuron (TDZ pode vir a beneficiar a produtividade de grãos. Dessa maneira, o objetivo do trabalho foi avaliar o efeito de doses de TDZ sobre a produtividade do arroz, na presença e ausência da inoculação foliar com Azospirillum brasilense. Foi utilizada a cultivar ANa 5015, no delineamento experimental de blocos casualizados em esquema fatorial 4 x 2, sendo quatro doses de TDZ (0,0; 0,5; 1,0 e 1,5g ha-1 aplicadas por ocasião do perfilhamento, 30 DAE, e da aplicação de Azospirillum brasilense (presença ou ausência em dose fixa aos 20 DAE. Verificou-se que a cultivar ANa 5015 não se mostrou responsiva para a inoculação foliar com Azospirillum brasilense na dose de 200 mL ha-1. Para as doses de TDZ aplicadas via foliar, houve uma variação significativa na altura de plantas, cuja dose de 0,41 g ha-1 resultou na altura máxima de 1,11 m. Não houve efeito das doses de TDZ na produtividade, massa de 100 grãos, número de panículas por m², grãos por panícula e massa hectolítrica.

  3. Tryptophan, thiamine and indole-3-acetic acid exchange between Chlorella sorokiniana and the plant growth-promoting bacterium Azospirillum brasilense.

    Science.gov (United States)

    Palacios, Oskar A; Gomez-Anduro, Gracia; Bashan, Yoav; de-Bashan, Luz E

    2016-06-01

    During synthetic mutualistic interactions between the microalga Chlorella sorokiniana and the plant growth-promoting bacterium (PGPB) Azospirillum brasilense, mutual exchange of resources involved in producing and releasing the phytohormone indole-3-acetic acid (IAA) by the bacterium, using tryptophan and thiamine released by the microalga, were measured. Although increased activities of tryptophan synthase in C. sorokiniana and indole pyruvate decarboxylase (IPDC) in A. brasilense were observed, we could not detect tryptophan or IAA in the culture medium when both organisms were co-immobilized. This indicates that no extra tryptophan or IAA is produced, apart from the quantities required to sustain the interaction. Over-expression of the ipdC gene occurs at different incubation times: after 48 h, when A. brasilense was immobilized alone and grown in exudates of C. sorokiniana and at 96 h, when A. brasilense was co-immobilized with the microalga. When A. brasilense was cultured in exudates of C. sorokiniana, increased expression of the ipdC gene, corresponding increase in activity of IPDC encoded by the ipdC gene, and increase in IAA production were measured during the first 48 h of incubation. IAA production and release by A. brasilense was found only when tryptophan and thiamine were present in a synthetic growth medium (SGM). The absence of thiamine in SGM yielded no detectable IAA. In summary, this study demonstrates that C. sorokiniana can exude sufficient tryptophan and thiamine to allow IAA production by a PGPB during their interaction. Thiamine is essential for IAA production by A. brasilense and these three metabolites are part of a communication between the two microorganisms. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  4. Hydrogenase activity in Azospirillum brasilense is inhibited by nitrite, nitric oxide, carbon monoxide, and acetylene

    Energy Technology Data Exchange (ETDEWEB)

    Tibelius, K.H.; Knowles, R.

    1984-10-01

    Nitrite, NO, CO, and C/sub 2/H/sub 2/ inhibited O/sub 2/-dependent H/sub 2/ uptake (H/sup 3/H oxidation) in denitrifying Azospirillum brasilense Sp7 grown anaerobically on N/sub 2/O or NO/sub 3//sup -/. The apparent K/sub i/ values for inhibition of O/sub 2/-dependent H/sub 2/ uptake were 20 ..mu..M for NO/sub 2//sup -/, 0.4 ..mu..M for NO, 28 ..mu..M for CO, and 88 ..mu..M for C/sub 2/H/sub 2/. These inhibitors also affected methylene blue-dependent H/sub 2/ uptake, presumably by acting directly on the hydrogenase. Nitrite and NO inhibited H/sub 2/ uptake irreversibly, whereas inhibition due to CO was easily reversed by repeatedly evacuating and backfilling with N/sub 2/. The C/sub 2/H/sub 2/ inhibition was not readily reversed, partly due to difficulty in removing the last traces of this gas from solution. The NO/sub 2//sup -/ inhibition of malate-dependent respiration was readily reversed by repeatedly washing the cells, in contrast to the effect of NO/sub 2//sup -/ on H/sub 2/-dependent respiration. These results suggest that the low hydrogenase activities observed in NO/sub 3//sup -/-grown cultures of A. brasilense may be due to the irreversible inhibition of hydrogenase by NO/sub 2//sup -/ and NO produced by NO/sub 3//sup -/ reduction.

  5. Characterization of two trpE genes encoding anthranilate synthase α-subunit in Azospirillum brasilense

    International Nuclear Information System (INIS)

    Ge Shimei; Xie Baoen; Chen Sanfeng

    2006-01-01

    The previous report from our laboratory has recently identified a new trpE gene (termed trpE 2 ) which exists independently in Azospirillum brasilense Yu62. In this study, amplification of trpE(G) (termed trpE 1 (G) here) confirmed that there are two copies of trpE gene, one trpE being fused into trpG while the other trpE existed independently. This is First report to suggest that two copies of the trpE gene exist in this bacterium. Comparison of the nucleotide sequence demonstrated that putative leader peptide, terminator, and anti-terminator were found upstream of trpE 1 (G) while these sequence features did not exist in front of trpE 2 . The β-galactosidase activity of an A. brasilense strain carrying a trpE 2 -lacZ fusion remained constant at different tryptophan concentrations, but the β-galactosidase activity of the same strain carrying a trpE 1 (G)-lacZ fusion decreased as the tryptophan concentration increased. These data suggest that the expression of trpE 1 (G) is regulated at the transcriptional level by attenuation while trpE 2 is constantly expressed. The anthranilate synthase assays with trpE 1 (G) - and trpE 2 - mutants demonstrated that TrpE 1 (G) fusion protein is feedback inhibited by tryptophan while TrpE 2 protein is not. We also found that both trpE 1 (G) and trpE 2 gene products were involved in IAA synthesis

  6. Mutants with Enhanced Nitrogenase Activity in Hydroponic Azospirillum brasilense-Wheat Associations

    Science.gov (United States)

    Pereg Gerk, Lily; Gilchrist, Kate; Kennedy, Ivan R.

    2000-01-01

    The effect of a mutation affecting flocculation, differentiation into cyst-like forms, and root colonization on nitrogenase expression by Azospirillum brasilense is described. The gene flcA of strain Sp7 restored these phenotypes in spontaneous mutants of both strains Sp7 and Sp245. Employing both constitutive pLA-lacZ and nifH-lacZ reporter fusions expressed in situ, the colony morphology, colonization pattern, and potential for nitrogenase activity of spontaneous mutants and flcA Tn5-induced mutants were established. The results of this study show that the ability of Sp7 and Sp245 mutant strains to remain in a vegetative form improved their ability to express nitrogenase activity in association with wheat in a hydroponic system. Restoring the cyst formation and colonization pattern to the spontaneous mutant Sp7-S reduced nitrogenase activity rates in association with plants to that of the wild-type Sp7. Although Tn5-induced flcA mutants showed higher potentials for nitrogenase expression than Sp7, their potentials were lower than that of Sp7-S, indicating that other factors in this strain contribute to its exceptional nitrogenase activity rates on plants. The lack of lateral flagella is not one of these factors, as Sp7-PM23, a spontaneous mutant impaired in swarming and lateral-flagellum production but not in flocculation, showed wild-type nitrogenase activity and expression. The results also suggest factors of importance in evolving an effective symbiosis between Azospirillum and wheat, such as increasing the availability of microaerobic niches along the root, increased supply of carbon sources by the plant, and the retention of the bacterial cells in vegetative form for faster metabolism. PMID:10788397

  7. [A STUDY OF THE ISOLATED BACTERIOPHAGE ΦAB-SP7 ADSORPTION ON THE CELL SURFACE OF THE AZOSPIRILLUM BRASILENSE SP7].

    Science.gov (United States)

    Guliy, O I; Karavaeva, O A; Velikov, V A; Sokolov, O I; Pavily, S A; Larionova, O S; Burov, A M; Ignatov, O V

    2016-01-01

    The bacteriophage ΦAb-Sp7 was isolated from the cells of the Azospirillum brasilense Sp7. The morphology, size of the gram-negative colonies, and range of lytic activity against other strains and species of the genus Azospirillum was tested. The isolated phage DNA was examined using electrophoretic and restriction analysis, and the size of the genome were established. The electron microscopy. resuIts show that the phage (capsid) has a strand-like form. The electron microscopy study of the bacteriophage ΦAb-Sp7 adsorption on the A. brasilense Sp7 bacterial surface was performed.

  8. The ipdC, hisC1 and hisC2 genes involved in indole-3-acetic production used as alternative phylogenetic markers in Azospirillum brasilense.

    Science.gov (United States)

    Jijón-Moreno, Saúl; Marcos-Jiménez, Cynthia; Pedraza, Raúl O; Ramírez-Mata, Alberto; de Salamone, I García; Fernández-Scavino, Ana; Vásquez-Hernández, Claudia A; Soto-Urzúa, Lucia; Baca, Beatriz E

    2015-06-01

    Plant growth-promoting bacteria of the genus Azospirillum are present in the rhizosphere and as endophytes of many crops. In this research we studied 40 Azospirillum strains isolated from different plants and geographic regions. They were first characterized by 16S rDNA restriction analysis, and their phylogenetic position was established by sequencing the genes 16S rDNA, ipdC, hisC1, and hisC2. The latter three genes are involved in the indole-3-pyruvic acid (IPyA) biosynthesis pathway of indole-3-acetic acid (IAA). Furthermore, the suitability of the 16S-23S rDNA intergenic spacer sequence (IGS) for the differentiation of closely related Azospirillum taxa and development of PCR protocols allows for specific detection of strains. The IGS-RFLP analysis enabled intraspecies differentiation, particularly of Azospirillum brasilense and Azospirillum lipoferum strains. Results demonstrated that the ipdC, hisC1, and hisC2 genes are highly conserved in all the assessed A. brasilense isolates, suggesting that these genes can be used as an alternative phylogenetic marker. In addition, IAA production determined by HPLC ranged from 0.17 to 98.2 μg mg(-1) protein. Southern hybridization with the A. brasilense ipdC gene probe did not show, a hybridization signal with A. lipoferum, Azospirillum amazonense, Azospirillum halopreferans and Azospirillum irakense genomic DNA. This suggests that these species produce IAA by other pathways. Because IAA is mainly synthesized via the IPyA pathway in A. brasilense strains, a species that is used worldwide in agriculture, the identification of ipdC, hisC1, and hisC2 genes by PCR may be suitable for selecting exploitable strains.

  9. Toxicidade de herbicidas utilizados na cultura da cana-de-açúcar à bactéria diazotrófica Azospirillum brasilense Toxicity of herbicides applied on sugarcane to the diazotrophic bacterium Azospirillum brasilense

    Directory of Open Access Journals (Sweden)

    S.O Procópio

    2011-01-01

    Full Text Available Objetivou-se neste trabalho identificar herbicidas utilizados na cultura da cana-de-açúcar que não alteram o crescimento ou a capacidade de fixação biológica de nitrogênio (FBN da bactéria diazotrófica Azospirillum brasi lense. Dezoito herbicidas - paraquat, ametryn, amicarbazone, diuron, metribuzin, [hexazinone + diuron], [hexazinone + clomazone], clomazone, isoxaflutole, sulfentrazone, oxyfluorfen, imazapic, imazapyr, [trifloxysulfuron-sodium + ametryn], S-metolachlor, glyphosate, MSMA e 2,4-D - foram testados em suas doses comerciais quanto ao impacto sobre o crescimento da bactéria em meio líquido DIGs. As variáveis capacidade de suporte de crescimento (carrying capacity do meio de cultura, duração da fase lag e tempo de geração de A. brasilense foram calculadas a partir de dados de densidade ótica obtidos, em intervalos regulares, durante a incubação de culturas por 55 h. O impacto dos herbicidas na atividade da nitrogenase de A. brasilense foi avaliado em meio semissólido NFb, sem N, pela técnica da atividade de redução do acetileno (ARA. Os efeitos dos herbicidas sobre as variáveis de crescimento e ARA foram comparados ao controle pelo teste de Dunnett. Paraquat, oxyfluorfen, [trifloxysulfuron-sodium + ametryn] e glyphosate reduziram a capacidade do meio DIGs em suportar o crescimento de A. brasilense. Esse efeito foi associado ao aumento da duração da fase lag e do tempo de geração para [trifloxysulfuron-sodium + ametryn] e ao aumento no tempo de geração para glyphosate. MSMA, paraquat e amicarbazone reduzem a FBN in vitro de A. brasilense, porém essa redução é mais severa na presença do paraquat. Os demais herbicidas não alteram o crescimento e a FBN de A. brasilense.The objective of this work was to identify the herbicides applied on sugarcane that do not affect the growth nor the process of biological nitrogen fixation (BNF of the diazotrophic bacterium Azospirillum brasilense. Commercial doses of

  10. Structural studies of the polysaccharides from the lipopolysaccharides of Azospirillum brasilense Sp246 and SpBr14.

    Science.gov (United States)

    Sigida, Elena N; Fedonenko, Yuliya P; Shashkov, Alexander S; Grinev, Vyacheslav S; Zdorovenko, Evelina L; Konnova, Svetlana A; Ignatov, Vladimir V; Knirel, Yuriy A

    2014-10-29

    Lipopolysaccharides from closely related Azospirillum brasilense strains, Sp246 and SpBr14, were obtained by phenol-water extraction. Mild acid hydrolysis of the lipopolysaccharides followed by GPC on Sephadex G-50 resulted in polysaccharide mixtures. On the basis of sugar and methylation analyses, Smith degradation and (1)H and (13)C NMR spectroscopy data, it was concluded that both bacteria possess the same two distinct polysaccharides having structures 1 and 2: [structure: see text]. Structure 1 has been reported earlier for a polysaccharide of A. brasilense 54 [Fedonenko et al., 2011] whereas to our knowledge structure 2 has not been hitherto found in bacterial polysaccharides. Copyright © 2014 Elsevier Ltd. All rights reserved.

  11. The chemotaxis-like Che1 pathway has an indirect role in adhesive cell properties of Azospirillum brasilense.

    Science.gov (United States)

    Siuti, Piro; Green, Calvin; Edwards, Amanda Nicole; Doktycz, Mitchel J; Alexandre, Gladys

    2011-10-01

    The Azospirillum brasilense chemotaxis-like Che1 signal transduction pathway was recently shown to modulate changes in adhesive cell surface properties that, in turn, affect cell-to-cell aggregation and flocculation behaviors rather than flagellar-mediated chemotaxis. Attachment to surfaces and root colonization may be functions related to flocculation. Here, the conditions under which A. brasilense wild-type Sp7 and che1 mutant strains attach to abiotic and biotic surfaces were examined using in vitro attachment and biofilm assays combined with atomic force microscopy and confocal microscopy. The nitrogen source available for growth is found to be a major modulator of surface attachment by A. brasilense and could be promoted in vitro by lectins, suggesting that it depends on interaction with surface-exposed residues within the extracellular matrix of cells. However, Che1-dependent signaling is shown to contribute indirectly to surface attachment, indicating that distinct mechanisms are likely underlying flocculation and attachment to surfaces in A. brasilense. © 2011 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

  12. Enhanced activity of ADP glucose pyrophosphorylase and formation of starch induced by Azospirillum brasilense in Chlorella vulgaris.

    Science.gov (United States)

    Choix, Francisco J; Bashan, Yoav; Mendoza, Alberto; de-Bashan, Luz E

    2014-05-10

    ADP-glucose pyrophosphorylase (AGPase) regulates starch biosynthesis in higher plants and microalgae. This study measured the effect of the bacterium Azospirillum brasilense on AGPase activity in the freshwater microalga Chlorella vulgaris and formation of starch. This was done by immobilizing both microorganisms in alginate beads, either replete with or deprived of nitrogen or phosphorus and all under heterotrophic conditions, using d-glucose or Na-acetate as the carbon source. AGPase activity during the first 72h of incubation was higher in C. vulgaris when immobilized with A. brasilense. This happened simultaneously with higher starch accumulation and higher carbon uptake by the microalgae. Either carbon source had similar effects on enzyme activity and starch accumulation. Starvation either by N or P had the same pattern on AGPase activity and starch accumulation. Under replete conditions, the population of C. vulgaris immobilized alone was higher than when immobilized together, but under starvation conditions A. brasilense induced a larger population of C. vulgaris. In summary, adding A. brasilense enhanced AGPase activity, starch formation, and mitigation of stress in C. vulgaris. Copyright © 2014 Elsevier B.V. All rights reserved.

  13. Inoculation with Bacillus subtilis and Azospirillum brasilense produces abscisic acid that reduces IRT1-mediated cadmium uptake of roots.

    Science.gov (United States)

    Xu, Qianru; Pan, Wei; Zhang, Ranran; Lu, Qi; Xue, Wanlei; Wu, Cainan; Song, Bixiu; Du, Shaoting

    2018-05-08

    Cadmium (Cd) contamination of agricultural soils represents a serious risk to crop safety. A new strategy using abscisic acid (ABA)-generating bacteria, Bacillus subtilis or Azospirillum brasilense, was developed to reduce the Cd accumulation in plants grown in Cd-contaminated soil. Inoculation with either bacterium resulted in a pronounced increase in the ABA level in wild-type Arabidopsis Col-0 plants, accompanied by a decrease in Cd levels in plant tissues, which mitigated the Cd toxicity. As a consequence, the growth of plants exposed to Cd was improved. Nevertheless, B. subtilis and A. brasilense inoculation had little effect on Cd levels and toxicity in the ABA-insensitive mutant snrk 2.2/2.3, indicating that the action of ABA is required for these bacteria to reduce Cd accumulation in plants. Furthermore, inoculation with either B. subtilis or A. brasilense down-regulated the expression of IRT1 (IRON-REGULATED TRANSPORTER 1) in the roots of wild-type plants and had little effect on Cd levels in the IRT1-knockout mutants irt1-1 and irt1-2. In summary, we conclude that B. subtilis and A. brasilense can reduce Cd levels in plants via an IRT1-dependent ABA-mediated mechanism.

  14. A CheR/CheB fusion protein is involved in cyst cell development and chemotaxis in Azospirillum brasilense Sp7.

    Science.gov (United States)

    Wu, Lixian; Cui, Yanhua; Hong, Yuanyuan; Chen, Sanfeng

    2011-12-20

    We here report the sequence and functional analysis of cstB of Azospirillum brasilense Sp7. The predicted cstB contains C-terminal two PAS domains and N-terminal part which has similarity with CheB-CheR fusion protein. cstB mutants had reduced swarming ability compared to that of A. brasilense wild-type strain, implying that cstB was involved in chemotaxis in A. brasilense. A microscopic analysis revealed that cstB mutants developed mature cyst cells more quickly than wild type, indicating that cstB is involved in cyst formation. cstB mutants were affected in colony morphology and the production of exopolysaccharides (EPS) which are essential for A. brasilense cells to differentiate into cyst-like forms. These observations suggested that cstB was a multi-effector involved in cyst development and chemotaxis in A. brasilense. Copyright © 2010 Elsevier GmbH. All rights reserved.

  15. Identification of an O-linked repetitive glycan chain of the polar flagellum flagellin of Azospirillum brasilense Sp7.

    Science.gov (United States)

    Belyakov, Alexei Ye; Burygin, Gennady L; Arbatsky, Nikolai P; Shashkov, Alexander S; Selivanov, Nikolai Yu; Matora, Larisa Yu; Knirel, Yuriy A; Shchyogolev, Sergei Yu

    2012-11-01

    This is the first report to have identified an O-linked repetitive glycan in bacterial flagellin, a structural protein of the flagellum. Studies by sugar analysis, Smith degradation, (1)H and (13)C NMR spectroscopy, and mass spectrometry showed that the glycan chains of the polar flagellum flagellin of the plant-growth-promoting rhizobacterium Azospirillum brasilense Sp7 are represented by a polysaccharide with a molecular mass of 7.7 kDa, which has a branched tetrasaccharide repeating unit of the following structure: Copyright © 2012. Published by Elsevier Ltd.

  16. Chemical synthesis of the tetrasaccharide repeating unit of the O-polysaccharide isolated from Azospirillum brasilense SR80.

    Science.gov (United States)

    Sarkar, Vikramjit; Mukhopadhyay, Balaram

    2015-04-10

    A linear strategy has been developed for the synthesis of the tetrasaccharide repeating unit of the O-polysaccharide from Azospirillum brasilense SR80. Stepwise glycosylation of the rationally protected thioglycoside donors activated by NIS in the presence of La(OTf)3 furnished the target tetrasaccharide. The glycosylation reactions resulted in the formation of the desired linkage with absolute stereoselectivity and afforded the required derivatives in good to excellent yields. The phthalimido group has been used as the precursor of the desired acetamido group to meet the requirement of 1,2-trans glycosidic linkage. Copyright © 2015 Elsevier Ltd. All rights reserved.

  17. Structural studies of the O-specific polysaccharide(s) from the lipopolysaccharide of Azospirillum brasilense type strain Sp7.

    Science.gov (United States)

    Sigida, Elena N; Fedonenko, Yuliya P; Shashkov, Alexander S; Zdorovenko, Evelina L; Konnova, Svetlana A; Ignatov, Vladimir V; Knirel, Yuriy A

    2013-10-18

    Lipopolysaccharide was obtained by phenol-water extraction from dried bacterial cells of Azospirillum brasilense type strain Sp7. Mild acid hydrolysis of the lipopolysaccharide followed by GPC on Sephadex G-50 resulted in a polysaccharide mixture, which was studied by composition and methylation analyses, Smith degradation and (1)H and (13)C NMR spectroscopy. The following polysaccharide structures were established, where italics indicate a non-stoichiometric (∼40%) 2-O-methylation of l-rhamnose. Copyright © 2013 Elsevier Ltd. All rights reserved.

  18. RpoH2 sigma factor controls the photooxidative stress response in a non-photosynthetic rhizobacterium, Azospirillum brasilense Sp7.

    Science.gov (United States)

    Kumar, Santosh; Rai, Ashutosh Kumar; Mishra, Mukti Nath; Shukla, Mansi; Singh, Pradhyumna Kumar; Tripathi, Anil Kumar

    2012-12-01

    Bacteria belonging to the Alphaproteobacteria normally harbour multiple copies of the heat shock sigma factor (known as σ(32), σ(H) or RpoH). Azospirillum brasilense, a non-photosynthetic rhizobacterium, harbours five copies of rpoH genes, one of which is an rpoH2 homologue. The genes around the rpoH2 locus in A. brasilense show synteny with that found in rhizobia. The rpoH2 of A. brasilense was able to complement the temperature-sensitive phenotype of the Escherichia coli rpoH mutant. Inactivation of rpoH2 in A. brasilense results in increased sensitivity to methylene blue and to triphenyl tetrazolium chloride (TTC). Exposure of A. brasilense to TTC and the singlet oxygen-generating agent methylene blue induced several-fold higher expression of rpoH2. Comparison of the proteome of A. brasilense with its rpoH2 deletion mutant and with an A. brasilense strain overexpressing rpoH2 revealed chaperone GroEL, elongation factors (Ef-Tu and EF-G), peptidyl prolyl isomerase, and peptide methionine sulfoxide reductase as the major proteins whose expression was controlled by RpoH2. Here, we show that the RpoH2 sigma factor-controlled photooxidative stress response in A. brasilense is similar to that in the photosynthetic bacterium Rhodobacter sphaeroides, but that RpoH2 is not involved in the detoxification of methylglyoxal in A. brasilense.

  19. Convergent synthesis of a tetrasaccharide repeating unit of the O-specific polysaccharide from the cell wall lipopolysaccharide of Azospirillum brasilense strain Sp7

    Directory of Open Access Journals (Sweden)

    Pintu Kumar Mandal

    2014-01-01

    Full Text Available A straightforward convergent synthesis has been carried out for the tetrasaccharide repeating unit of the O-specific cell wall lipopolysaccharide of the strain Sp7 of Azospirillum brasilense. The target tetrasaccharide has been synthesized from suitably protected monosaccharide intermediates in 42% overall yield in seven steps by using a [2 + 2] block glycosylation approach.

  20. Enzyme Production and Nitrogen Fixation by Free, Immobilized and Coimmobilized Inoculants of Trichoderma harzianum and Azospirillum brasilense and Their Possible Role in Growth Promotion of Tomato

    Directory of Open Access Journals (Sweden)

    Momein H. El-Katatny

    2010-01-01

    Full Text Available A plant growth-promoting rhizobacterium (Azospirillum brasilense strain Az and a biocontrol fungus (Trichoderma harzianum strain T24 have been evaluated for their individual and combined production of hydrolytic enzymes, nitrogen fixation and their possible role in growth promotion of tomato seedlings. The studied organisms were inoculated as free or calcium alginate-encapsulated cells. All freshly prepared macrobeads showed high encapsulation capacity (EC/% of inocula compared with dry macrobeads. Results of enzyme production did not exhibit consistent pattern of the effect of encapsulation process on enzyme production. Beads entrapping bacterial and/or fungal cells were used successfully in 3 repeated cycles in the presence of fresh sterile culture medium in each growth cycle. Enzyme production by immobilized bacterial and/or fungal cells increased as the growth cycles were repeated. Co-culturing of A. brasilense with T. harzianum (free or immobilized in semisolid nitrogen deficient medium (N-free medium enabled A. brasilense to fix nitrogen on pectin, chitin and carboxymethyl cellulose. The activity of nitrogen fixation by A. brasilense in the case of single and combined cultures with Trichoderma (using dry encapsulated beads into the sterile soil increased with the addition of carbon source. Most of inoculations with free or alginate macrobead formulations of T. harzianum and/or A. brasilense showed significant increase in the growth parameters of tomato seedlings. The root system grew more profusely in the case of all seeds treated with A. brasilense. The growth parameters of Az/T24-treated seeds using dry coimmobilized macrobeads were higher than those of the untreated control. Moreover, the effect was improved significantly in soil enriched with different C sources. Enhanced tomato seedling growth after the co-inoculation could be due to the synergistic effect of both Trichoderma and Azospirillum. Finally, co-inoculation with Azospirillum

  1. Phenotypical and molecular responses of Arabidopsis thaliana roots as a result of inoculation with the auxin-producing bacterium Azospirillum brasilense.

    Science.gov (United States)

    Spaepen, Stijn; Bossuyt, Stijn; Engelen, Kristof; Marchal, Kathleen; Vanderleyden, Jos

    2014-02-01

    The auxin-producing bacterium Azospirillum brasilense Sp245 can promote the growth of several plant species. The model plant Arabidopsis thaliana was chosen as host plant to gain an insight into the molecular mechanisms that govern this interaction. The determination of differential gene expression in Arabidopsis roots after inoculation with either A. brasilense wild-type or an auxin biosynthesis mutant was achieved by microarray analysis. Arabidopsis thaliana inoculation with A. brasilense wild-type increases the number of lateral roots and root hairs, and elevates the internal auxin concentration in the plant. The A. thaliana root transcriptome undergoes extensive changes on A. brasilense inoculation, and the effects are more pronounced at later time points. The wild-type bacterial strain induces changes in hormone- and defense-related genes, as well as in plant cell wall-related genes. The A. brasilense mutant, however, does not elicit these transcriptional changes to the same extent. There are qualitative and quantitative differences between A. thaliana responses to the wild-type A. brasilense strain and the auxin biosynthesis mutant strain, based on both phenotypic and transcriptomic data. This illustrates the major role played by auxin in the Azospirillum-Arabidopsis interaction, and possibly also in other bacterium-plant interactions. © 2013 The Authors. New Phytologist © 2013 New Phytologist Trust.

  2. Residual effect of nitrogen fertilization and Azospirillum brasilense inoculation in the maize cultureEfeito residual da adubação nitrogenada e inoculação de Azospirillum brasilense na cultura do milho

    Directory of Open Access Journals (Sweden)

    Jackson Huzar Novakowiski

    2011-12-01

    Full Text Available The diazotrophic bacteria Azospirillum brasilense is an organism able to fix nitrogen of atmosphere and produce plant hormones. Nevertheless, there is lack of information with regard to use in field conditions, especially in production systems that have presence of animals in a determined year period. The objective of paper was to evaluate the association of the nitrogen residual effect of fertilization in pasture winter and the inoculation with A. brasilense in the maize culture. Were carried two experiments in Guarapuava (PR in season 2008/09 with randomized block design with split plots in three replication. The main parcel consisted of application 5 levels of N (0, 75, 150, 225 e 300 kg ha-1 in pasture of black oat and ryegrass occupied by bovines and 4 treatments in the maize (T1 = control; T2 = inoculation of A. brasilense; T3 = 75 kg ha-1 of N; T4 = 150 kg ha-1 of N. Were evaluated: plants population, ears per plant, productivity, mass thousand grains, damage grains, row per ear and grains per row. There was residual effect of nitrogen applied in the pasture on maize culture. The mass thousand grains and the number of rows per ear of maize presented quadratic response for increase of nitrogen level in the pasture. The inoculation of A. brasilense provided higher productivity than control same with increase the nitrogen level applied in the pasture, with quadratic response in the experiment 1 and linear in the experiment 2.A bactéria diazotrófica Azospirillum brasilense é um organismo capaz de fixar nitrogênio da atmosfera e produzir hormônios vegetais. No entanto, há carência de informações a respeito de seu uso em condições de campo, sobretudo em sistemas de produção que tem a presença de animais em um determinado período do ano. O objetivo do trabalho foi avaliar a associação do efeito residual da adubação nitrogenada na pastagem de inverno e a inoculação de A. brasilense na cultura do milho. Foram conduzidos dois

  3. Bacteriophytochrome controls carotenoid-independent response to photodynamic stress in a non-photosynthetic rhizobacterium, Azospirillum brasilense Sp7.

    Science.gov (United States)

    Kumar, Santosh; Kateriya, Suneel; Singh, Vijay Shankar; Tanwar, Meenakshi; Agarwal, Shweta; Singh, Hina; Khurana, Jitendra Paul; Amla, Devinder Vijay; Tripathi, Anil Kumar

    2012-01-01

    Ever since the discovery of the role of bacteriophytochrome (BphP) in inducing carotenoid synthesis in Deinococcus radiodurans in response to light the role of BphPs in other non-photosynthetic bacteria is not clear yet. Azospirillum brasilense, a non-photosynthetic rhizobacterium, harbours a pair of BphPs out of which AbBphP1 is a homolog of AtBphP1 of Agrobacterium tumefaciens. By overexpression, purification, biochemical and spectral characterization we have shown that AbBphP1 is a photochromic bacteriophytochrome. Phenotypic study of the ΔAbBphP1 mutant showed that it is required for the survival of A. brasilense on minimal medium under red light. The mutant also showed reduced chemotaxis towards dicarboxylates and increased sensitivity to the photooxidative stress. Unlike D. radiodurans, AbBphP1 was not involved in controlling carotenoid synthesis. Proteome analysis of the ΔAbBphP1 indicated that AbBphP1 is involved in inducing a cellular response that enables A. brasilense in regenerating proteins that might be damaged due to photodynamic stress.

  4. Involvement of indole-3-acetic acid produced by Azospirillum brasilense in accumulating intracellular ammonium in Chlorella vulgaris.

    Science.gov (United States)

    Meza, Beatriz; de-Bashan, Luz E; Bashan, Yoav

    2015-01-01

    Accumulation of intracellular ammonium and activities of the enzymes glutamine synthetase (GS) and glutamate dehydrogenase (GDH) were measured when the microalgae Chlorella vulgaris was immobilized in alginate with either of two wild type strains of Azospirillum brasilense or their corresponding indole-3-acetic acid (IAA)-attenuated mutants. After 48 h of immobilization, both wild types induced higher levels of intracellular ammonium in the microalgae than their respective mutants; the more IAA produced, the higher the intracellular ammonium accumulated. Accumulation of intracellular ammonium in the cells of C. vulgaris followed application of four levels of exogenous IAA reported for A. brasilense and its IAA-attenuated mutants, which had a similar pattern for the first 24 h. This effect was transient and disappeared after 48 h of incubation. Immobilization of C. vulgaris with any bacteria strain induced higher GS activity. The bacterial strains also had GS activity, comparable to the activity detected in C. vulgaris, but weaker than when immobilized with the bacteria. When net activity was calculated, the wild type always induced higher GS activity than IAA-attenuated mutants. GDH activity in most microalgae/bacteria interactions resembled GS activity. When complementing IAA-attenuated mutants with exogenous IAA, GS activity in co-immobilized cultures matched those of the wild type A. brasilense immobilized with the microalga. Similarity occurred when the net GS activity was measured, and was higher with greater quantities of exogenous IAA. It is proposed that IAA produced by A. brasilense is involved in ammonium uptake and later assimilation by C. vulgaris. Copyright © 2014 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.

  5. Co2 +  interaction with Azospirillum brasilense Sp7 cells: a 57Co emission Mössbauer spectroscopic study

    International Nuclear Information System (INIS)

    Kamnev, Alexander A.; Tugarova, Anna V.; Biró, Borbála; Kovács, Krisztina; Homonnay, Zoltán; Kuzmann, Ernő; Vértes, Attila

    2012-01-01

    Preliminary 57 Co emission Mössbauer spectroscopic data were obtained for the soil bacterium Azospirillum brasilense Sp7 (T = 80 K) in frozen 57 Co 2 +  -containing suspensions and in their dried residues. The Mössbauer parameters were compared with those for A. brasilense strain Sp245 differing from strain Sp7 by ecological behaviour. Live cells of both strains showed metabolic transformations of 57 Co 2 +  within an hour. Differences in the parameters observed for the two strains under similar conditions suggest dissimilarities in their metabolic response to Co 2 +  .

  6. Spectroscopic characterization of cell membranes and their constituents of the plant-associated soil bacterium Azospirillum brasilense

    Science.gov (United States)

    Kamnev, A. A.; Antonyuk, L. P.; Matora, L. Yu.; Serebrennikova, O. B.; Sumaroka, M. V.; Colina, M.; Renou-Gonnord, M.-F.; Ignatov, V. V.

    1999-05-01

    Structural and compositional features of bacterial membranes and some of their isolated constituents (cell surface lipopolysaccharide, phospholipids) of the plant-growth-promoting diazotrophic rhizobacterium Azospirillum brasilense (wild-type strain Sp245) were characterized using Fourier transform infrared (FTIR) spectroscopy and some other techniques. FTIR spectra of the cell membranes were shown to comprise the main vibration modes of the relevant lipopolysaccharide and protein components which are believed to be involved in associative plant-bacterium interactions, as well as of phospholipid constituents. The role and functions of metal cations in the structural organization and physicochemical properties of bacterial cell membranes are also discussed considering their accumulation in the membranes from the culture medium.

  7. Fourier transform Raman spectroscopic characterisation of cells of the plant-associated soil bacterium Azospirillum brasilense Sp7

    Science.gov (United States)

    Kamnev, A. A.; Tarantilis, P. A.; Antonyuk, L. P.; Bespalova, L. A.; Polissiou, M. G.; Colina, M.; Gardiner, P. H. E.; Ignatov, V. V.

    2001-05-01

    Structural and compositional features of bacterial cell samples and of lipopolysaccharide-protein complex isolated from the cell surface of the plant-growth-promoting rhizobacterium Azospirillum brasilense (wild-type strain Sp7) were characterised using Fourier transform (FT) Raman spectroscopy. The structural spectroscopic information obtained is analysed and considered together with analytical data on the content of metal cations (Co 2+, Cu 2+ and Zn 2+) in the bacterial cells grown in a standard medium as well as in the presence of each of the cations (0.2 mM). The latter, being taken up by bacterial cells from the culture medium in significant amounts, were shown to induce certain metabolic changes in the bacterium revealed in FT-Raman spectra, which is discussed from the viewpoint of bacterial response to environmental stresses.

  8. Effect of Azospirillum brasilense and Burkholderia unamae Bacteria on Maize Photosynthetic Activity Evaluated Using the Photoacoustic Technique

    Science.gov (United States)

    Gordillo-Delgado, F.; Marín, E.; Calderón, A.

    2016-09-01

    In this work, the photosynthetic process of maize plants ( Zea mays), which were grown using seeds inoculated with plant growth promoting bacteria Azospirillum brasilense and Burkholderia unamae, was monitored. Photothermal and photobaric signals obtained by a time-resolved photoacoustic measurement configuration were used for measuring the oxygen evolution rate in situ. A frequency-resolved configuration of the method was utilized to determine the oxygen diffusion coefficient and the thermal diffusivity of the maize leaves. The latter parameters, which can be used as indicators of the photosynthetic activity of maize, are found to vary according to the plant-microbe interaction. Treatment with plant growth promoting bacteria induced a decrease in the oxygen diffusion coefficient of about 20 %.

  9. Mössbauer spectroscopic study of 57Fe metabolic transformations in the rhizobacterium Azospirillum brasilense Sp245

    Science.gov (United States)

    Kamnev, Alexander A.; Tugarova, Anna V.; Kovács, Krisztina; Biró, Borbála; Homonnay, Zoltán; Kuzmann, Ernő

    2014-04-01

    Preliminary 57Fe transmission Mössbauer spectroscopic data were obtained for the first time for live cells of the plant-growth-promoting rhizobacterium Azospirillum brasilense (wild-type strain Sp245) grown aerobically with 57FeIII-nitrilotriacetate (NTA) complex as a sole source of iron. The results obtained have shown that live cells actively reduce part of the assimilated iron(III) to iron(II), the latter amounting up to 33 % of total cellular iron after 18 h of growth, and 48 % after additional 3 days of storage of the dense wet cell suspension in nutrient-free saline solution in air at room temperature (measured at 80 K). The cellular iron(II) was found to be represented by two quadrupole doublets of different high-spin forms, while the parameters of the cellular iron(III) were close to those typical for bacterioferritins.

  10. Carotenoid Biosynthetic Pathways Are Regulated by a Network of Multiple Cascades of Alternative Sigma Factors in Azospirillum brasilense Sp7.

    Science.gov (United States)

    Rai, Ashutosh Kumar; Dubey, Ashutosh Prakash; Kumar, Santosh; Dutta, Debashis; Mishra, Mukti Nath; Singh, Bhupendra Narain; Tripathi, Anil Kumar

    2016-11-01

    Carotenoids constitute an important component of the defense system against photooxidative stress in bacteria. In Azospirillum brasilense Sp7, a nonphotosynthetic rhizobacterium, carotenoid synthesis is controlled by a pair of extracytoplasmic function sigma factors (RpoEs) and their cognate zinc-binding anti-sigma factors (ChrRs). Its genome harbors two copies of the gene encoding geranylgeranyl pyrophosphate synthase (CrtE), the first critical step in the carotenoid biosynthetic pathway in bacteria. Inactivation of each of two crtE paralogs found in A. brasilense caused reduction in carotenoid content, suggesting their involvement in carotenoid synthesis. However, the effect of crtE1 deletion was more pronounced than that of crtE2 deletion. Out of the five paralogs of rpoH in A. brasilense, overexpression of rpoH1 and rpoH2 enhanced carotenoid synthesis. Promoters of crtE2 and rpoH2 were found to be dependent on RpoH2 and RpoE1, respectively. Using a two-plasmid system in Escherichia coli, we have shown that the crtE2 gene of A. brasilense Sp7 is regulated by two cascades of sigma factors: one consisting of RpoE1and RpoH2 and the other consisting of RpoE2 and RpoH1. In addition, expression of crtE1 was upregulated indirectly by RpoE1 and RpoE2. This study shows, for the first time in any carotenoid-producing bacterium, that the regulation of carotenoid biosynthetic pathway involves a network of multiple cascades of alternative sigma factors. Carotenoids play a very important role in coping with photooxidative stress in prokaryotes and eukaryotes. Although extracytoplasmic function (ECF) sigma factors are known to directly regulate the expression of carotenoid biosynthetic genes in bacteria, regulation of carotenoid biosynthesis by one or multiple cascades of sigma factors had not been reported. This study provides the first evidence of the involvement of multiple cascades of sigma factors in the regulation of carotenoid synthesis in any bacterium by showing the

  11. Enhanced accumulation of starch and total carbohydrates in alginate-immobilized Chlorella spp. induced by Azospirillum brasilense: I. Autotrophic conditions.

    Science.gov (United States)

    Choix, Francisco J; de-Bashan, Luz E; Bashan, Yoav

    2012-10-10

    The effect of the microalgae-growth promoting bacterium Azospirillum brasilense on accumulation of total carbohydrates and starch in two species of Chlorella (Chlorella vulgaris and Chlorella sorokiniana), when the bacterium and each microalga were jointly immobilized in alginate beads was studied under autotrophic conditions for 144 h in synthetic medium. The interaction of the bacterium with the microalgae enhanced accumulation of total carbohydrate and starch. Cells of Chlorella accumulated the highest amounts of carbohydrate after incubation for 24h. Yet, this did not coincide with the highest affinity and volumetric productivity measured in these cultures. However, after incubation for 72 h, mainly in jointly immobilized treatments of both microalgae species, the cultures reached their highest total carbohydrate content (mainly as starch) and also the highest affinity and volumetric productivity. These results demonstrate the potential of A. brasilense to affect carbohydrates and starch accumulation in Chlorella spp. when both microorganisms are co-cultured, which can be an important tool for applications of microalgae. Copyright © 2012. Published by Elsevier Inc.

  12. Enhanced accumulation of starch and total carbohydrates in alginate-immobilized Chlorella spp. induced by Azospirillum brasilense: II. Heterotrophic conditions.

    Science.gov (United States)

    Choix, Francisco J; de-Bashan, Luz E; Bashan, Yoav

    2012-10-10

    The effect of the bacterium Azospirillum brasilense jointly immobilized with Chlorella vulgaris or C. sorokiniana in alginate beads on total carbohydrates and starch was studied under dark and heterotrophic conditions for 144 h in synthetic growth medium supplemented with either d-glucose or Na-acetate as carbon sources. In all treatments, enhanced total carbohydrates and starch content per culture and per cell was obtained after 24h; only jointly immobilized C. vulgaris growing on d-glucose significantly increased total carbohydrates and starch content after 96 h. Enhanced accumulation of carbohydrate and starch under jointly immobilized conditions was variable with time of sampling and substrate used. Similar results occurred when the microalgae was immobilized alone. In both microalgae growing on either carbon sources, the bacterium promoted accumulation of carbohydrates and starch; when the microalgae were immobilized alone, they used the carbon sources for cell multiplication. In jointly immobilized conditions with Chlorella spp., affinity to carbon source and volumetric productivity and yield were higher than when Chlorella spp. were immobilized alone; however, the growth rate was higher in microalgae immobilized alone. This study demonstrates that under heterotrophic conditions, A. brasilense promotes the accumulation of carbohydrates in two strains Chlorella spp. under certain time-substrate combinations, producing mainly starch. As such, this bacterium is a biological factor that can change the composition of compounds in microalgae in dark, heterotrophic conditions. Copyright © 2012. Published by Elsevier Inc.

  13. Biofertilization with Azospirillum brasilense improves in vitro culture of Handroanthus ochraceus, a forestry, ornamental and medicinal plant.

    Science.gov (United States)

    Llorente, Berta E; Alasia, María A; Larraburu, Ezequiel E

    2016-01-25

    Biofertilization with plant growth-promoting rhizobacteria is a potential alternative to plant productivity. Here, in vitro propagation of Handroanthus ochraceus (yellow lapacho), a forest crop with high economic and environmental value, was developed using the Azospirillum brasilense strains Cd and Az39 during rhizogenesis. Epicotiles of in vitro plantlets were multiplied in Woody Plant Medium (WPM). For rooting, elongated shoots were transferred to auxin-free Murashige-Skoog medium with Gamborg's vitamins and WPM, both at half salt concentration (½MSG and ½WPM), and inoculated with Cd or Az39 at the base of each shoot. Anatomical studies were performed using leaves cleared and stained with safranin for optical microscopy and leaves and roots metalized with gold-palladium for scanning electron microscopy (SEM). In ½WPM auxin-free medium, A. brasilense Cd inoculation produced 55% of rooting, increased root fresh and dry weight (45% and 77%, respectively), and led to lower stomata size and density with similar proportion of open and closed stomata. Both strains selectively increased the size or density of glandular trichomes in ½MSG. Moreover, bacteria were detected on the root surface by SEM. In conclusion, the difference in H. ochraceus response to A. brasilense inoculation depends on the strain and the plant culture media. Cd strain enhanced rooting in auxin-free ½WPM and produced plantlets with features similar to those expected in ex vitro plants. This work presents an innovative in vitro approach using beneficial plant-microorganism interaction as an ecologically compatible strategy in plant biotechnology. Copyright © 2015 Elsevier B.V. All rights reserved.

  14. Azospirillum IV

    International Nuclear Information System (INIS)

    Klingmuller, W.

    1988-01-01

    This book's contents include: Advances in the genetics of Azospirillum brasilense Sp7: Use of Tn5 mutagenesis for gene mapping and identification; Characterization of DNA segments adjacent to the nifHDK genes of Azospirillum brasilense by Sp7 Tn5 site-directed mutagenesis; Selection at the chemostat of Azospirillum brasilense Cd N 2 -fixing at high O 2 pressure. Root hair deformation induced on maize and medicago by an Azospirillum transconjugant containing a Rhizobium meliloti nodulation region. Azospirilla are bacteria that live in association with the roots of many grain crops. Since these bacteria bind molecular nitrogen from the air and excrete plant growth substances, interest has focussed on their potential to increase crop yields

  15. Azospirillum IV

    Energy Technology Data Exchange (ETDEWEB)

    Klingmuller, W.

    1988-01-01

    This book's contents include: Advances in the genetics of Azospirillum brasilense Sp7: Use of Tn5 mutagenesis for gene mapping and identification; Characterization of DNA segments adjacent to the nifHDK genes of Azospirillum brasilense by Sp7 Tn5 site-directed mutagenesis; Selection at the chemostat of Azospirillum brasilense Cd N/sub 2/-fixing at high O/sub 2/ pressure. Root hair deformation induced on maize and medicago by an Azospirillum transconjugant containing a Rhizobium meliloti nodulation region. Azospirilla are bacteria that live in association with the roots of many grain crops. Since these bacteria bind molecular nitrogen from the air and excrete plant growth substances, interest has focussed on their potential to increase crop yields.

  16. Assessment of SCAR markers to design real-time PCR primers for rhizosphere quantification of Azospirillum brasilense phytostimulatory inoculants of maize.

    Science.gov (United States)

    Couillerot, O; Poirier, M-A; Prigent-Combaret, C; Mavingui, P; Caballero-Mellado, J; Moënne-Loccoz, Y

    2010-08-01

    To assess the applicability of sequence characterized amplified region (SCAR) markers obtained from BOX, ERIC and RAPD fragments to design primers for real-time PCR quantification of the phytostimulatory maize inoculants Azospirillum brasilense UAP-154 and CFN-535 in the rhizosphere. Primers were designed based on strain-specific SCAR markers and were screened for successful amplification of target strain and absence of cross-reaction with other Azospirillum strains. The specificity of primers thus selected was verified under real-time PCR conditions using genomic DNA from strain collection and DNA from rhizosphere samples. The detection limit was 60 fg DNA with pure cultures and 4 x 10(3) (for UAP-154) and 4 x 10(4) CFU g(-1) (for CFN-535) in the maize rhizosphere. Inoculant quantification was effective from 10(4) to 10(8) CFU g(-1) soil. BOX-based SCAR markers were useful to find primers for strain-specific real-time PCR quantification of each A. brasilense inoculant in the maize rhizosphere. Effective root colonization is a prerequisite for successful Azospirillum phytostimulation, but cultivation-independent monitoring methods were lacking. The real-time PCR methods developed here will help understand the effect of environmental conditions on root colonization and phytostimulation by A. brasilense UAP-154 and CFN-535.

  17. Interspecific cooperation: enhanced growth, attachment and strain-specific distribution in biofilms through Azospirillum brasilense-Pseudomonas protegens co-cultivation.

    Science.gov (United States)

    Pagnussat, Luciana A; Salcedo, Florencia; Maroniche, Guillermo; Keel, Christoph; Valverde, Claudio; Creus, Cecilia M

    2016-10-01

    Plant-growth-promoting bacteria belonging to Azospirillum and Pseudomonas genera are major inhabitants of the rhizosphere. Both are increasingly commercialized as crops inoculants. Interspecific interaction in the rhizosphere is critical for inoculants aptness. The objective of this work was to evaluate Azospirillum and Pseudomonas interaction in mixed biofilms by co-cultivation of the model strains Azospirillum brasilense Sp245 and Pseudomonas protegens CHA0. The results revealed enhanced growth of both strains when co-cultured in static conditions. Moreover, Sp245 biofilm formed in plastic surfaces was increased 2-fold in the presence of CHA0. Confocal microscopy revealed highly structured mixed biofilms showing Sp245 mainly on the bottom and CHA0 towards the biofilm surface. In addition, A. brasilense biofilm was thicker and denser when co-cultured with P. protegens. In a colony-colony interaction assay, Sp245 changed nearby CHA0 producing small colony phenotype, which accounts for a diffusible metabolite mediator; though CHA0 spent medium did not affect Sp245 colony phenotype. Altogether, these results point to a cooperative interaction between A. brasilense Sp245 and P. protegens CHA0 in which both strains increase their static growth and produce structured mixed biofilms with a strain-specific distribution. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  18. Accumulation of fatty acids in Chlorella vulgaris under heterotrophic conditions in relation to activity of acetyl-CoAcarboxylase, temperature, and co-immobilization with Azospirillum brasilense [corrected].

    Science.gov (United States)

    Leyva, Luis A; Bashan, Yoav; Mendoza, Alberto; de-Bashan, Luz E

    2014-10-01

    The relation between fatty acid accumulation, activity of acetyl-CoA carboxylase (ACC), and consequently lipid accumulation was studied in the microalgae Chlorella vulgaris co-immobilized with the plant growth-promoting bacterium Azospirillum brasilense under dark heterotrophic conditions with Na acetate as a carbon source. In C. vulgaris immobilized alone, cultivation experiments for 6 days showed that ACC activity is directly related to fatty acid accumulation, especially in the last 3 days. In co-immobilization experiments, A. brasilense exerted a significant positive effect over ACC activity, increased the quantity in all nine main fatty acids, increased total lipid accumulation in C. vulgaris, and mitigated negative effects of nonoptimal temperature for growth. No correlation between ACC activity and lipid accumulation in the cells was established for three different temperatures. This study demonstrated that the interaction between A. brasilense and C. vulgaris has a significant effect on fatty acid and lipid accumulation in the microalgae.

  19. Accumulation fatty acids of in Chlorella vulgaris under heterotrophic conditions in relation to activity of acetyl-CoA carboxylase, temperature, and co-immobilization with Azospirillum brasilense

    Science.gov (United States)

    Leyva, Luis A.; Bashan, Yoav; Mendoza, Alberto; de-Bashan, Luz E.

    2014-10-01

    The relation between fatty acid accumulation, activity of acetyl-CoA carboxylase (ACC), and consequently lipid accumulation was studied in the microalgae Chlorella vulgaris co-immobilized with the plant growth-promoting bacterium Azospirillum brasilense under dark heterotrophic conditions with Na acetate as a carbon source. In C. vulgaris immobilized alone, cultivation experiments for 6 days showed that ACC activity is directly related to fatty acid accumulation, especially in the last 3 days. In co-immobilization experiments, A. brasilense exerted a significant positive effect over ACC activity, increased the quantity in all nine main fatty acids, increased total lipid accumulation in C. vulgaris, and mitigated negative effects of nonoptimal temperature for growth. No correlation between ACC activity and lipid accumulation in the cells was established for three different temperatures. This study demonstrated that the interaction between A. brasilense and C. vulgaris has a significant effect on fatty acid and lipid accumulation in the microalgae.

  20. [Genome Rearrangements in Azospirillum brasilense Sp7 with the Involvement of the Plasmid pRhico and the Prophage phiAb-Cd].

    Science.gov (United States)

    Katsy, E I; Petrova, L P

    2015-12-01

    Alphaproteobacteria of the species Azospirillum brasilense have a multicomponent genome that undergoes frequent spontaneous rearrangements, yielding changes in the plasmid profiles of strains. Specifically, variants (Cd, Sp7.K2, Sp7.1, Sp7.4, Sp7.8, etc.) of the type strainA. brasilense Sp7 that had lost a 115-MDa plasmid were previously selected. In many of them, the molecular weight of a 90-MDa plasmid (p90 or pRhico), which is a kind of "depot" for glycopolymer biosynthesis genes, increased. In this study, a collection of primers was designed to the plasmid pRhico and to the DNA of prophage phiAb-Cd integrated in it. The use ofthese primers in polymerase chain reactions allowed the detection of the probable excision of phiAb-Cd phage from the DNA of A. brasilense variants Sp7.4 and Sp7.8 and other alterations of the pRhico structure in A. brasilense strains Cd, Sp7.K2, and Sp7.8. The developed primers and PCR conditions may be recoin mended for primary analysis of spontaneous plasmid rearrangements in A. brasilense Sp7 and related strains.

  1. Influence of tryptophan and indole-3-acetic acid on starch accumulation in the synthetic mutualistic Chlorella sorokiniana-Azospirillum brasilense system under heterotrophic conditions.

    Science.gov (United States)

    Palacios, Oskar A; Choix, Francisco J; Bashan, Yoav; de-Bashan, Luz E

    2016-06-01

    This study measured the relations between tryptophan production, the phytohormone indole-3-acetic acid (IAA) and the metabolism and accumulation of starch during synthetic mutualism between the microalgae Chlorella sorokiniana and the microalgae growth-promoting bacteria Azospirillum brasilense, created by co-immobilization in alginate beads. Experiments used two wild-type A. brasilense strains (Cd and Sp6) and an IAA-attenuated mutant (SpM7918) grown under nitrogen-replete and nitrogen-starved conditions tested under dark, heterotrophic and aerobic growth conditions. Under all incubating conditions, C. sorokiniana, but not A. brasilense, produced tryptophan. A significant correlation between IAA-production by A. brasilense and starch accumulation in C. sorokiniana was found, since the IAA-attenuated mutant was not producing increased starch levels. The highest ADP-glucose pyrophosphorylase (AGPase) activity, starch content and glucose uptake were found during the interaction of A. brasilense wild type strains with the microalgae. When the microalgae were grown alone, they produced only small amounts of starch. Supplementation with synthetic IAA to C. sorokiniana grown alone enhanced the above parameters, but only transiently. Activity of α-amylase decreased under nitrogen-replete conditions, but increased under nitrogen-starved conditions. In summary, this study demonstrated that, during synthetic mutualism, the exchange of tryptophan and IAA between the partners is a mechanism that governs several changes in starch metabolism of C. sorokiniana, yielding an increase in starch content. Copyright © 2016 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.

  2. Regulation of expression and biochemical characterization of a beta-class carbonic anhydrase from the plant growth-promoting rhizobacterium, Azospirillum brasilense Sp7.

    Science.gov (United States)

    Kaur, Simarjot; Mishra, Mukti Nath; Tripathi, Anil K

    2009-10-01

    Carbonic anhydrase (CA; [EC 4.2.1.1]) is a ubiquitous enzyme catalysing the reversible hydration of CO(2) to bicarbonate, a reaction that supports various biochemical and physiological functions. Genome analysis of Azospirillum brasilense, a nonphotosynthetic, nitrogen-fixing, rhizobacterium, revealed an ORF with homology to beta-class carbonic anhydrases (CAs). Biochemical characteristics of the beta-class CA of A. brasilense, analysed after cloning the gene (designated as bca), overexpressing in Escherichia coli and purifying the protein by affinity purification, revealed that the native recombinant enzyme is a homotetramer, inhibited by the known CA inhibitors. CA activity in A. brasilense cell extracts, reverse transcriptase (RT)-PCR and Western blot analyses showed that bca was constitutively expressed under aerobic conditions. Lower beta-galactosidase activity in A. brasilense cells harbouring bca promoter: lacZ fusion during the stationary phase or during growth on 3% CO(2) enriched air or at acidic pH indicated that the transcription of bca was downregulated by the stationary phase, elevated CO(2) levels and acidic pH conditions. These observations were also supported by RT-PCR analysis. Thus, beta-CA in A. brasilense seems to be required for scavenging CO(2) from the ambient air and the requirement of CO(2) hydration seems to be higher for the cultures growing exponentially at neutral to alkaline pH.

  3. In Azospirillum brasilense, mutations in flmA or flmB genes affect polar flagellum assembly, surface polysaccharides, and attachment to maize roots.

    Science.gov (United States)

    Rossi, Fernando Ariel; Medeot, Daniela Beatriz; Liaudat, Juan Pablo; Pistorio, Mariano; Jofré, Edgardo

    2016-09-01

    Azospirillum brasilense is a soil bacterium capable of promoting plant growth. Several surface components were previously reported to be involved in the attachment of A. brasilense to root plants. Among these components are the exopolysaccharide (EPS), lipopolysaccharide (LPS) and the polar flagellum. Flagellin from polar flagellum is glycosylated and it was suggested that genes involved in such a posttranslational modification are the same ones involved in the biosynthesis of sugars present in the O-antigen of the LPS. In this work, we report on the characterization of two homologs present in A. brasilense Cd, to the well characterized flagellin modification genes, flmA and flmB, from Aeromonas caviae. We show that mutations in either flmA or flmB genes of A. brasilense resulted in non-motile cells due to alterations in the polar flagellum assembly. Moreover, these mutations also affected the capability of A. brasilense cells to adsorb to maize roots and to produce LPS and EPS. By generating a mutant containing the polar flagellum affected in their rotation, we show the importance of the bacterial motility for the early colonization of maize roots. Copyright © 2016 Elsevier GmbH. All rights reserved.

  4. Expression and characterization of an N-truncated form of the NifA protein of Azospirillum brasilense

    Directory of Open Access Journals (Sweden)

    C.Y. Nishikawa

    2012-02-01

    Full Text Available Azospirillum brasilense is a nitrogen-fixing bacterium associated with important agricultural crops such as rice, wheat and maize. The expression of genes responsible for nitrogen fixation (nif genes in this bacterium is dependent on the transcriptional activator NifA. This protein contains three structural domains: the N-terminal domain is responsible for the negative control by fixed nitrogen; the central domain interacts with the RNA polymerase σ54 co-factor and the C-terminal domain is involved in DNA binding. The central and C-terminal domains are linked by the interdomain linker (IDL. A conserved four-cysteine motif encompassing the end of the central domain and the IDL is probably involved in the oxygen-sensitivity of NifA. In the present study, we have expressed, purified and characterized an N-truncated form of A. brasilense NifA. The protein expression was carried out in Escherichia coli and the N-truncated NifA protein was purified by chromatography using an affinity metal-chelating resin followed by a heparin-bound resin. Protein homogeneity was determined by densitometric analysis. The N-truncated protein activated in vivo nifH::lacZ transcription regardless of fixed nitrogen concentration (absence or presence of 20 mM NH4Cl but only under low oxygen levels. On the other hand, the aerobically purified N-truncated NifA protein bound to the nifB promoter, as demonstrated by an electrophoretic mobility shift assay, implying that DNA-binding activity is not strictly controlled by oxygen levels. Our data show that, while the N-truncated NifA is inactive in vivo under aerobic conditions, it still retains DNA-binding activity, suggesting that the oxidized form of NifA bound to DNA is not competent to activate transcription.

  5. Expression and characterization of an N-truncated form of the NifA protein of Azospirillum brasilense

    Energy Technology Data Exchange (ETDEWEB)

    Nishikawa, C.Y.; Araújo, L.M.; Kadowaki, M.A.S.; Monteiro, R.A.; Steffens, M.B.R.; Pedrosa, F.O.; Souza, E.M.; Chubatsu, L.S. [Departamento de Bioquímica e Biologia Molecular, Universidade Federal do Paraná, Curitiba, PR (Brazil)

    2012-01-27

    Azospirillum brasilense is a nitrogen-fixing bacterium associated with important agricultural crops such as rice, wheat and maize. The expression of genes responsible for nitrogen fixation (nif genes) in this bacterium is dependent on the transcriptional activator NifA. This protein contains three structural domains: the N-terminal domain is responsible for the negative control by fixed nitrogen; the central domain interacts with the RNA polymerase σ{sup 54} factor and the C-terminal domain is involved in DNA binding. The central and C-terminal domains are linked by the interdomain linker (IDL). A conserved four-cysteine motif encompassing the end of the central domain and the IDL is probably involved in the oxygen-sensitivity of NifA. In the present study, we have expressed, purified and characterized an N-truncated form of A. brasilense NifA. The protein expression was carried out in Escherichia coli and the N-truncated NifA protein was purified by chromatography using an affinity metal-chelating resin followed by a heparin-bound resin. Protein homogeneity was determined by densitometric analysis. The N-truncated protein activated in vivo nifH::lacZ transcription regardless of fixed nitrogen concentration (absence or presence of 20 mM NH{sub 4}Cl) but only under low oxygen levels. On the other hand, the aerobically purified N-truncated NifA protein bound to the nifB promoter, as demonstrated by an electrophoretic mobility shift assay, implying that DNA-binding activity is not strictly controlled by oxygen levels. Our data show that, while the N-truncated NifA is inactive in vivo under aerobic conditions, it still retains DNA-binding activity, suggesting that the oxidized form of NifA bound to DNA is not competent to activate transcription.

  6. The Azospirillum brasilense Che1 chemotaxis pathway controls swimming velocity, which affects transient cell-to-cell clumping.

    Science.gov (United States)

    Bible, Amber; Russell, Matthew H; Alexandre, Gladys

    2012-07-01

    The Che1 chemotaxis-like pathway of Azospirillum brasilense contributes to chemotaxis and aerotaxis, and it has also been found to contribute to regulating changes in cell surface adhesive properties that affect the propensity of cells to clump and to flocculate. The exact contribution of Che1 to the control of chemotaxis and flocculation in A. brasilense remains poorly understood. Here, we show that Che1 affects reversible cell-to-cell clumping, a cellular behavior in which motile cells transiently interact by adhering to one another at their nonflagellated poles before swimming apart. Clumping precedes and is required for flocculation, and both processes appear to be independently regulated. The phenotypes of a ΔaerC receptor mutant and of mutant strains lacking cheA1, cheY1, cheB1, or cheR1 (alone or in combination) or with che1 deleted show that Che1 directly mediates changes in the flagellar swimming velocity and that this behavior directly modulates the transient nature of clumping. Our results also suggest that an additional receptor(s) and signaling pathway(s) are implicated in mediating other Che1-independent changes in clumping identified in the present study. Transient clumping precedes the transition to stable clump formation, which involves the production of specific extracellular polysaccharides (EPS); however, production of these clumping-specific EPS is not directly controlled by Che1 activity. Che1-dependent clumping may antagonize motility and prevent chemotaxis, thereby maintaining cells in a metabolically favorable niche.

  7. Revealing strategies of quorum sensing in Azospirillum brasilense strains Ab-V5 and Ab-V6.

    Science.gov (United States)

    Fukami, Josiane; Abrantes, Julia Laura Fernandes; Del Cerro, Pablo; Nogueira, Marco Antonio; Ollero, Francisco Javier; Megías, Manuel; Hungria, Mariangela

    2018-01-01

    Azospirillum brasilense is an important plant-growth promoting bacterium (PGPB) that requires several critical steps for root colonization, including biofilm and exopolysaccharide (EPS) synthesis and cell motility. In several bacteria these mechanisms are mediated by quorum sensing (QS) systems that regulate the expression of specific genes mediated by the autoinducers N-acyl-homoserine lactones (AHLs). We investigated QS mechanisms in strains Ab-V5 and Ab-V6 of A. brasilense, which are broadly used in commercial inoculants in Brazil. Neither of these strains carries a luxI gene, but there are several luxR solos that might perceive AHL molecules. By adding external AHLs we verified that biofilm and EPS production and cell motility (swimming and swarming) were regulated via QS in Ab-V5, but not in Ab-V6. Differences were observed not only between strains, but also in the specificity of LuxR-type receptors to AHL molecules. However, Ab-V6 was outstanding in indole acetic acid (IAA) synthesis and this molecule might mimic AHL signals. We also applied the quorum quenching (QQ) strategy, obtaining transconjugants of Ab-V5 and Ab-V6 carrying a plasmid with acyl-homoserine lactonase. When maize (Zea mays L.) was inoculated with the wild-type and transconjugant strains, plant growth was decreased with the transconjugant of Ab-V5-confirming the importance of an AHL-mediated QS system-but did not affect plant growth promotion by Ab-V6.

  8. Expression and characterization of an N-truncated form of the NifA protein of Azospirillum brasilense.

    Science.gov (United States)

    Nishikawa, C Y; Araújo, L M; Kadowaki, M A S; Monteiro, R A; Steffens, M B R; Pedrosa, F O; Souza, E M; Chubatsu, L S

    2012-02-01

    Azospirillum brasilense is a nitrogen-fixing bacterium associated with important agricultural crops such as rice, wheat and maize. The expression of genes responsible for nitrogen fixation (nif genes) in this bacterium is dependent on the transcriptional activator NifA. This protein contains three structural domains: the N-terminal domain is responsible for the negative control by fixed nitrogen; the central domain interacts with the RNA polymerase σ(54) co-factor and the C-terminal domain is involved in DNA binding. The central and C-terminal domains are linked by the interdomain linker (IDL). A conserved four-cysteine motif encompassing the end of the central domain and the IDL is probably involved in the oxygen-sensitivity of NifA. In the present study, we have expressed, purified and characterized an N-truncated form of A. brasilense NifA. The protein expression was carried out in Escherichia coli and the N-truncated NifA protein was purified by chromatography using an affinity metal-chelating resin followed by a heparin-bound resin. Protein homogeneity was determined by densitometric analysis. The N-truncated protein activated in vivo nifH::lacZ transcription regardless of fixed nitrogen concentration (absence or presence of 20 mM NH(4)Cl) but only under low oxygen levels. On the other hand, the aerobically purified N-truncated NifA protein bound to the nifB promoter, as demonstrated by an electrophoretic mobility shift assay, implying that DNA-binding activity is not strictly controlled by oxygen levels. Our data show that, while the N-truncated NifA is inactive in vivo under aerobic conditions, it still retains DNA-binding activity, suggesting that the oxidized form of NifA bound to DNA is not competent to activate transcription.

  9. Expression and characterization of an N-truncated form of the NifA protein of Azospirillum brasilense

    International Nuclear Information System (INIS)

    Nishikawa, C.Y.; Araújo, L.M.; Kadowaki, M.A.S.; Monteiro, R.A.; Steffens, M.B.R.; Pedrosa, F.O.; Souza, E.M.; Chubatsu, L.S.

    2012-01-01

    Azospirillum brasilense is a nitrogen-fixing bacterium associated with important agricultural crops such as rice, wheat and maize. The expression of genes responsible for nitrogen fixation (nif genes) in this bacterium is dependent on the transcriptional activator NifA. This protein contains three structural domains: the N-terminal domain is responsible for the negative control by fixed nitrogen; the central domain interacts with the RNA polymerase σ 54 factor and the C-terminal domain is involved in DNA binding. The central and C-terminal domains are linked by the interdomain linker (IDL). A conserved four-cysteine motif encompassing the end of the central domain and the IDL is probably involved in the oxygen-sensitivity of NifA. In the present study, we have expressed, purified and characterized an N-truncated form of A. brasilense NifA. The protein expression was carried out in Escherichia coli and the N-truncated NifA protein was purified by chromatography using an affinity metal-chelating resin followed by a heparin-bound resin. Protein homogeneity was determined by densitometric analysis. The N-truncated protein activated in vivo nifH::lacZ transcription regardless of fixed nitrogen concentration (absence or presence of 20 mM NH 4 Cl) but only under low oxygen levels. On the other hand, the aerobically purified N-truncated NifA protein bound to the nifB promoter, as demonstrated by an electrophoretic mobility shift assay, implying that DNA-binding activity is not strictly controlled by oxygen levels. Our data show that, while the N-truncated NifA is inactive in vivo under aerobic conditions, it still retains DNA-binding activity, suggesting that the oxidized form of NifA bound to DNA is not competent to activate transcription

  10. Vescicular-arbuscular mycorrhiza and Azospirillum brasilense rhizocoenosis in pearlmillet in a semi-arid soil

    International Nuclear Information System (INIS)

    Tilak, K.V.B.R.; Sachdev, M.S.; Sachdev, Pamila

    2007-01-01

    A field experiment was conducted in an alluvial sandy loam soil using Pearlmillet as the test crop to study the effect of Vescicular-Arbuscular Mycorrhiza (VAM) and Azospirillum with phosphorus on yield and other parameters. Dual inoculation gave a significant increase in Azospirillum and VAM infection in root over the control plants, and resulted in significant increase in grain yield. Combined inoculation alongwith N and P application showed maximum P uptake. Nitrogen fixation increased with plant growth with dually inoculated N and P treatment, The effect was more pronounced in the presence of phosphrous indicating that P is required for nitrogen fixation. (author)

  11. Structure and thermodynamics of effector molecule binding to the nitrogen signal transduction PII protein GlnZ from Azospirillum brasilense.

    Science.gov (United States)

    Truan, Daphné; Bjelić, Saša; Li, Xiao-Dan; Winkler, Fritz K

    2014-07-29

    The trimeric PII signal transduction proteins regulate the function of a variety of target proteins predominantly involved in nitrogen metabolism. ATP, ADP and 2-oxoglutarate (2-OG) are key effector molecules influencing PII binding to targets. Studies of PII proteins have established that the 20-residue T-loop plays a central role in effector sensing and target binding. However, the specific effects of effector binding on T-loop conformation have remained poorly documented. We present eight crystal structures of the Azospirillum brasilense PII protein GlnZ, six of which are cocrystallized and liganded with ADP or ATP. We find that interaction with the diphosphate moiety of bound ADP constrains the N-terminal part of the T-loop in a characteristic way that is maintained in ADP-promoted complexes with target proteins. In contrast, the interactions with the triphosphate moiety in ATP complexes are much more variable and no single predominant interaction mode is apparent except for the ternary MgATP/2-OG complex. These conclusions can be extended to most investigated PII proteins of the GlnB/GlnK subfamily. Unlike reported for other PII proteins, microcalorimetry reveals no cooperativity between the three binding sites of GlnZ trimers for any of the three effectors under carefully controlled experimental conditions. Copyright © 2014 Elsevier Ltd. All rights reserved.

  12. cDNA-AFLP analysis of differential gene expression related to cell chemotactic and encystment of Azospirillum brasilense.

    Science.gov (United States)

    Li, Huamin; Cui, Yanhua; Wu, Lixian; Tu, Ran; Chen, Sanfeng

    2011-12-20

    Our previous study indicated org35 was involved in chemotaxis and interacted with nitrogen fixation transcriptional activator NifA via PAS domain. In order to reveal the role of org35 in nitrogen regulation, the downstream target genes of org35 were identified. We here report differentially expressed genes in org35 mutants comparing with wild type Sp7 by means of cDNA-AFLP. Four up-regulated transcript-derived fragments (TDFs) homologues of chemotaxis transduction proteins were found, including CheW, methyl-accepting chemotaxis protein and response regulator CheY-like receiver. Three distinct TDFs (AB46, AB58 and AB63) were similar to PHB de-polymerase C-terminus, cell shape-determining protein and flagellin domain protein. And 11 TDFs showed similarities with signal transduction proteins, including homologous protein of the nitrogen regulation protein NtrY and nitrate/nitrite response regulator protein NarL. These data suggested that the Azospirillum brasilense org35 was a multi-effecter and involved in chemotaxis, cyst development and regulation of nitrogen fixation. Copyright © 2010 Elsevier GmbH. All rights reserved.

  13. Dual RNA-seq transcriptional analysis of wheat roots colonized by Azospirillum brasilense reveals up-regulation of nutrient acquisition and cell cycle genes.

    Science.gov (United States)

    Camilios-Neto, Doumit; Bonato, Paloma; Wassem, Roseli; Tadra-Sfeir, Michelle Z; Brusamarello-Santos, Liziane C C; Valdameri, Glaucio; Donatti, Lucélia; Faoro, Helisson; Weiss, Vinicius A; Chubatsu, Leda S; Pedrosa, Fábio O; Souza, Emanuel M

    2014-05-16

    The rapid growth of the world's population demands an increase in food production that no longer can be reached by increasing amounts of nitrogenous fertilizers. Plant growth promoting bacteria (PGPB) might be an alternative to increase nitrogenous use efficiency (NUE) in important crops such wheat. Azospirillum brasilense is one of the most promising PGPB and wheat roots colonized by A. brasilense is a good model to investigate the molecular basis of plant-PGPB interaction including improvement in plant-NUE promoted by PGPB. We performed a dual RNA-Seq transcriptional profiling of wheat roots colonized by A. brasilense strain FP2. cDNA libraries from biological replicates of colonized and non-inoculated wheat roots were sequenced and mapped to wheat and A. brasilense reference sequences. The unmapped reads were assembled de novo. Overall, we identified 23,215 wheat expressed ESTs and 702 A. brasilense expressed transcripts. Bacterial colonization caused changes in the expression of 776 wheat ESTs belonging to various functional categories, ranging from transport activity to biological regulation as well as defense mechanism, production of phytohormones and phytochemicals. In addition, genes encoding proteins related to bacterial chemotaxi, biofilm formation and nitrogen fixation were highly expressed in the sub-set of A. brasilense expressed genes. PGPB colonization enhanced the expression of plant genes related to nutrient up-take, nitrogen assimilation, DNA replication and regulation of cell division, which is consistent with a higher proportion of colonized root cells in the S-phase. Our data support the use of PGPB as an alternative to improve nutrient acquisition in important crops such as wheat, enhancing plant productivity and sustainability.

  14. Expression of alkyl hydroperoxide reductase is regulated negatively by OxyR1 and positively by RpoE2 sigma factor in Azospirillum brasilense Sp7.

    Science.gov (United States)

    Singh, Sudhir; Dwivedi, Susheel Kumar; Singh, Vijay Shankar; Tripathi, Anil Kumar

    2016-10-01

    OxyR proteins are LysR-type transcriptional regulators, which play an important role in responding to oxidative stress in bacteria. Azospirillum brasilense Sp7 harbours two copies of OxyR. The inactivation of the oxyR1, the gene organized divergently to ahpC in A. brasilense Sp7, led to an increased tolerance to alkyl hydroperoxides, which was corroborated by an increase in alkyl hydroperoxide reductase (AhpC) activity, enhanced expression of ahpC :lacZ fusion and increased synthesis of AhpC protein in the oxyR1::km mutant. The upstream region of ahpC promoter harboured a putative OxyR binding site, T-N11-A. Mutation of T, A or both in the T-N11-Amotif caused derepression of ahpC in A. brasilense suggesting that T-N11-A might be the binding site for a negative regulator. Retardation of the electrophoretic mobility of the T-N11-A motif harbouring oxyR1-ahpC intergenic DNA by recombinant OxyR1, under reducing as well as oxidizing conditions, indicated that OxyR1 acts as a negative regulator of ahpC in A. brasilense. Sequence of the promoter of ahpC, predicted on the basis of transcriptional start site, and an enhanced expression of ahpC:lacZ fusion in chrR2::km mutant background suggested that ahpC promoter was RpoE2 dependent. Thus, this study shows that in A. brasilense Sp7, ahpC expression is regulated negatively by OxyR1 but is regulated positively by RpoE2, an oxidative-stress-responsive sigma factor. It also shows that OxyR1 regulates the expression RpoE1, which is known to play an important role during photooxidative stress in A. brasilense.

  15. Study of the rhizobacterium Azospirillum brasilense Sp245 using Mössbauer spectroscopy with a high velocity resolution: Implication for the analysis of ferritin-like iron cores

    Science.gov (United States)

    Alenkina, I. V.; Oshtrakh, M. I.; Tugarova, A. V.; Biró, B.; Semionkin, V. A.; Kamnev, A. A.

    2014-09-01

    The results of a comparative study of two samples of the rhizobacterium Azospirillum brasilense (strain Sp245) prepared in different conditions and of human liver ferritin using Mössbauer spectroscopy with a high velocity resolution demonstrated the presence of ferritin-like iron (i.e. iron similar to that found in ferritin-like proteins) in the bacterium. Mössbauer spectra of these samples were fitted in two ways: as a rough approximation using a one quadrupole doublet fit (the homogeneous iron core model) and using a superposition of quadrupole doublets (the heterogeneous iron core model). Both results demonstrated differences in the Mössbauer parameters for mammalian ferritin and for bacterial ferritin-like iron. Moreover, some differences in the Mössbauer parameters were observed between the two samples of A. brasilense Sp245 related to the differences in their preparation conditions.

  16. Physiological, structural and molecular traits activated in strawberry plants after inoculation with the plant growth-promoting bacterium Azospirillum brasilense REC3.

    Science.gov (United States)

    Guerrero-Molina, M F; Lovaisa, N C; Salazar, S M; Martínez-Zamora, M G; Díaz-Ricci, J C; Pedraza, R O

    2015-05-01

    The plant growth-promoting strain REC3 of Azospirillum brasilense, isolated from strawberry roots, prompts growth promotion and systemic protection against anthracnose disease in this crop. Hence, we hypothesised that A. brasilense REC3 can induce different physiological, structural and molecular responses in strawberry plants. Therefore, the aim of this work was to study these traits activated in Azospirillum-colonised strawberry plants, which have not been assessed until now. Healthy, in vitro micropropagated plants were root-inoculated with REC3 under hydroponic conditions; root and leaf tissues were sampled at different times, and oxidative burst, phenolic compound content, malondialdehyde (MDA) concentration, callose deposition, cell wall fortification and gene expression were evaluated. Azospirillum inoculation enhanced levels of soluble phenolic compounds after 12 h post-inoculation (hpi), while amounts of cell wall bound phenolics were similar in inoculated and control plants. Other early responses activated by REC3 (at 24 hpi) were a decline of lipid peroxidation and up-regulation of strawberry genes involved in defence (FaPR1), bacterial recognition (FaFLS2) and H₂O₂ depuration (FaCAT and FaAPXc). The last may explain the apparent absence of oxidative burst in leaves after bacterial inoculation. Also, REC3 inoculation induced delayed structural responses such as callose deposition and cell wall fortification (at 72 hpi). Results showed that A. brasilense REC3 is capable of exerting beneficial effects on strawberry plants, reinforcing their physiological and cellular characteristics, which in turns contribute to improve plant performance. © 2014 German Botanical Society and The Royal Botanical Society of the Netherlands.

  17. Accumulation of intra-cellular polyphosphate in Chlorella vulgaris cells is related to indole-3-acetic acid produced by Azospirillum brasilense.

    Science.gov (United States)

    Meza, Beatriz; de-Bashan, Luz E; Hernandez, Juan-Pablo; Bashan, Yoav

    2015-06-01

    Accumulation of intra-cellular phosphate, as polyphosphate, was measured when the microalga Chlorella vulgaris was immobilized in alginate with either of two wild-type strains of the microalgae growth-promoting bacterium Azospirillum brasilense or their corresponding IAA-attenuated mutants. Wild type strains of A. brasilense induced higher amounts of intra-cellular phosphate in Chlorella than their respective mutants. Calculations comparing intra-cellular phosphate accumulation by culture or net accumulation by the cell and the amount of IAA that was produced by each of these strains revealed that higher IAA was linked to higher accumulations of intra-cellular phosphate. Application of four levels of exogenous IAA reported for A. brasilense and their IAA-attenuated mutants to cultures of C. vulgaris enhanced accumulation of intra-cellular phosphate; the higher the content of IAA per culture or per single cell, the higher was the amount of accumulated phosphate. When an IAA-attenuated mutant was complemented with exogenous IAA, accumulation of intra-cellular phosphate at the culture level was even higher than phosphate accumulation with the respective wild type strains. When calculating the net accumulation of intra-cellular phosphate in the complementation experiment, net intra-cellular phosphate induced by the IAA-attenuated mutant was completely restored and was similar to the wild strains. We propose that IAA produced by A. brasilense is linked to polyphosphate accumulation in C. vulgaris. Copyright © 2015 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.

  18. Assessing the efficacy of co-inoculation of wheat seedlings with the associative bacteria Paenibacillus polymyxa 1465 and Azospirillum brasilense Sp245.

    Science.gov (United States)

    Yegorenkova, Irina V; Tregubova, Kristina V; Burygin, Gennady L; Matora, Larisa Y; Ignatov, Vladimir V

    2016-03-01

    Co-inoculation of associative bacteria, which have high nitrogen-fixing activity, tolerance for environmental conditions, and the ability to compete with the natural microflora, is used widely to enhance the growth and yields of agricultural plants. We evaluated the ability of 2 co-inoculated plant-growth-promoting rhizobacteria, Paenibacillus polymyxa 1465 and Azospirillum brasilense Sp245, to colonize roots of wheat (Triticum aestivum L. 'Saratovskaya 29') seedlings, and we assessed the morphometric parameters of wheat early in its development. Analysis by ELISA with polyclonal antibodies raised against the exopolysaccharide of P. polymyxa 1465 and the lipopolysaccharide of A. brasilense Sp245 demonstrated that the root-colonizing activity of A. brasilense was higher when the bacterium was co-inoculated with P. polymyxa than when it was inoculated singly. Immunofluorescence microscopy with Alexa Fluor 532-labeled antibodies revealed sites of attachment of co-inoculated P. polymyxa and A. brasilense and showed that the 2 bacteria colonized similar regions of the roots. Co-inoculation exerted a negative effect on wheat seedling development, inhibiting root length by 17.6%, total root weight by 11%, and total shoot weight by 12%. Under certain conditions, dual inoculation of wheat may prove ineffective, apparently owing to the competition between the rhizobacteria for colonization sites on the plant roots. The findings from this study may aid in developing techniques for mixed bacterial inoculation of cultivated plants.

  19. [Mutants of bacterium Azospirillum brasilense Sp245 with Omegon insertion in mmsB or fabG genes of lipid metabolism are defective in motility and flagellation].

    Science.gov (United States)

    Kovtunov, E A; Shelud'ko, A V; Chernyshova, M P; Petrova, L P; Katsy, E I

    2013-11-01

    Bacteria Azospirillum brasilense have mixed flagellation: in addition to the polar flagellum, numerous lateral flagella are formed in their cells on medium with increased density. Flagella determine the active swimming and swarming capacities of azospirilla. Using A. brasilense Sp245 as an example, we showed that the Omegon-Km artificial transposon insertion into the chromosomal gene for 3-hydroxyisobutyrate dehydrogenase (mmsB) was concurrent with the appearance of significant defects in the formation of polar flagella and with the paralysis of lateral flagella. The Sp245 mutant with the Omegon insertion into the plasmid AZOBR_p1-borne gene for 3-oxoacyl-[acyl-carrier protein]-reductase (fabG) showed the complete loss of flagella and the swarming capacity, as well as significant defects in polar flagellar assembly (though some cells are still motile in liquid medium). The viability of the A. brasilense Sp245 mutants with the Omegon insertion into the mmsB or fabG gene was not reduced. No considerable differences in the fatty acid composition of whole cell lipid extracts were found for the A. brasilense Sp245 strain and its mmsB and fabG mutants.

  20. Early plant growth and biochemical responses induced by Azospirillum brasilense Sp245 lipopolysaccharides in wheat (Triticum aestivum L.) seedlings are attenuated by procyanidin B2.

    Science.gov (United States)

    Vallejo-Ochoa, Juan; López-Marmolejo, Mariel; Hernández-Esquivel, Alma Alejandra; Méndez-Gómez, Manuel; Suárez-Soria, Laura Nicolasa; Castro-Mercado, Elda; García-Pineda, Ernesto

    2018-03-01

    This study analyzes the effects of procyanidin B2 on early wheat plant growth and plant biochemical responses promoted by lipopolysaccharides (LPS) derived from the rhizobacteria Azospirillum brasilense Sp245. Measurements of leaf, root length, fresh weight, and dry weight showed in vitro plant growth stimulation 4 days after treatment with A. brasilense as well as LPS. Superoxide anion (O 2 ·- ) and hydrogen peroxide (H 2 O 2 ) levels increased in seedling roots treated with LPS (100 μg mL -1 ). The chlorophyll content in leaf decreased while the starch content increased 24 h after treatment in seedling roots. The LPS treatment induced a high increase in total peroxidase (POX) (EC 1.11.1.7) activity and ionically bound cell wall POX content in roots, when compared to respective controls. Early plant growth and biochemical responses observed in wheat seedlings treated with LPS were inhibited by the addition of procyanidin B2 (5 μg mL -1 ), a B type proanthocyanidin (PAC), plant-derived polyphenolic compound with binding properties of LPS. All results suggest first that the ionically bound cell wall POX enzymes could be a molecular target of A. brasilense LPS, and second that the recognition or association of LPS by plant cells is required to activate plant responses. This last event could play a critical role during plant growth regulation by A. brasilense LPS.

  1. Efecto de fertilizantes y herbicidas sobre el crecimiento in vitro de Azospirillum brasilense C16

    OpenAIRE

    Romero-Perdomo, Felipe; Criollo Campos, Paola Jimena; Rodríguez, Andrea Jineth; Rusinque, Mauricio Camelo; Bonilla Buitrago, Ruth Rebeca

    2015-01-01

    El objetivo del presente estudio fue evaluar la influencia de fertilizantes (urea, fosfato diamónico y cloruro de potasio) y herbicidas (glifosato y 2,4-D) sobre la viabilidad de A. brasilense C16. Dicha viabilidad fue cuantificada en tres concentraciones de cada agroquímico, en un medio mínimo de sal, a las 0, 12 y 24 horas de crecimiento. Los resultados demostraron que el tipo de agroquímico, su concentración y el tiempo de exposición influyeron sobre C16 (p

  2. Effects of Azospirillum brasilense with genetically modified auxin biosynthesis gene ipdC upon the diversity of the indigenous microbiota of the wheat rhizosphere.

    Science.gov (United States)

    Baudoin, Ezékiel; Lerner, Anat; Mirza, M Sajjad; El Zemrany, Hamdy; Prigent-Combaret, Claire; Jurkevich, Edouard; Spaepen, Stijn; Vanderleyden, Jos; Nazaret, Sylvie; Okon, Yaacov; Moënne-Loccoz, Yvan

    2010-04-01

    The phytostimulatory properties of Azospirillum inoculants, which entail production of the phytohormone indole-3-acetic acid (IAA), can be enhanced by genetic means. However, it is not known whether this could affect their interactions with indigenous soil microbes. Here, wheat seeds were inoculated with the wild-type strain Azospirillum brasilense Sp245 or one of three genetically modified (GM) derivatives and grown for one month. The GM derivatives contained a plasmid vector harboring the indole-3-pyruvate/phenylpyruvate decarboxylase gene ipdC (IAA production) controlled either by the constitutive promoter PnptII or the root exudate-responsive promoter PsbpA, or by an empty vector (GM control). All inoculants displayed equal rhizosphere population densities. Only inoculation with either ipdC construct increased shoot biomass compared with the non-inoculated control. At one month after inoculation, automated ribosomal intergenic spacer analysis (ARISA) revealed that the effect of the PsbpA construct on bacterial community structure differed from that of the GM control, which was confirmed by 16S rDNA-based denaturing gradient gel electrophoresis (DGGE). The fungal community was sensitive to inoculation with the PsbpA construct and especially the GM control, based on ARISA data. Overall, fungal and bacterial communities displayed distinct responses to inoculation of GM A. brasilense phytostimulators, whose effects could differ from those of the wild-type.

  3. The cyclic-di-GMP diguanylate cyclase CdgA has a role in biofilm formation and exopolysaccharide production in Azospirillum brasilense.

    Science.gov (United States)

    Ramírez-Mata, Alberto; López-Lara, Lilia I; Xiqui-Vázquez, Ma Luisa; Jijón-Moreno, Saúl; Romero-Osorio, Angelica; Baca, Beatriz E

    2016-04-01

    In bacteria, proteins containing GGDEF domains are involved in production of the second messenger c-di-GMP. Here we report that the cdgA gene encoding diguanylate cyclase A (CdgA) is involved in biofilm formation and exopolysaccharide (EPS) production in Azospirillum brasilense Sp7. Biofilm quantification using crystal violet staining revealed that inactivation of cdgA decreased biofilm formation. In addition, confocal laser scanning microscopy analysis of green-fluorescent protein-labeled bacteria showed that, during static growth, the biofilms had differential levels of development: bacteria harboring a cdgA mutation exhibited biofilms with considerably reduced thickness compared with those of the wild-type Sp7 strain. Moreover, DNA-specific staining and treatment with DNase I, and epifluorescence studies demonstrated that extracellular DNA and EPS are components of the biofilm matrix in Azospirillum. After expression and purification of the CdgA protein, diguanylate cyclase activity was detected. The enzymatic activity of CdgA-producing cyclic c-di-GMP was determined using GTP as a substrate and flavin adenine dinucleotide (FAD(+)) and Mg(2)(+) as cofactors. Together, our results revealed that A. brasilense possesses a functional c-di-GMP biosynthesis pathway. Copyright © 2016 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.

  4. Characterization of Cell Surface and EPS Remodeling of Azospirillum brasilense Chemotaxis-like 1 Signal Transduction Pathway mutants by Atomic Force Microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Billings, Amanda N [ORNL; Siuti, Piro [ORNL; Bible, Amber [University of Tennessee, Knoxville (UTK); Alexandre, Gladys [University of Tennessee, Knoxville (UTK); Retterer, Scott T [ORNL; Doktycz, Mitchel John [ORNL; Morrell-Falvey, Jennifer L [ORNL

    2011-01-01

    To compete in complex microbial communities, bacteria must quickly sense environmental changes and adjust cellular functions for optimal growth. Chemotaxis-like signal transduction pathways are implicated in the modulation of multiple cellular responses, including motility, EPS production, and cell-to-cell interactions. Recently, the Che1 chemotaxis-like pathway from Azospirillum brasilense was shown to modulate flocculation. In A. brasilense, cell surface properties, including EPS production, are thought to play a direct role in promoting flocculation. Using atomic force microscopy (AFM), we have detected distinct changes in the surface morphology of flocculating A. brasilense Che1 mutant strains that are absent in the wild type strain. Whereas the wild type strain produces a smooth mucosal extracellular matrix, the flocculating Che1 mutant strains produce distinctive extracellular fibril structures. Further analyses using flocculation inhibition and lectin-binding assays suggest that the composition of EPS components in the extracellular matrix differs between the cheA1 and cheY1 mutants, despite an apparent similarity in the macroscopic floc structures. Collectively, these data indicate that mutations in the Che1 pathway that result in increased flocculation are correlated with distinctive changes in the extracellular matrix structure produced by the mutants, including likely changes in the EPS structure and/or composition.

  5. Effect of ATP and 2-oxoglutarate on the in vitro interaction between the NifA GAF domain and the GlnB protein of Azospirillum brasilense

    International Nuclear Information System (INIS)

    Sotomaior, P.; Araújo, L.M.; Nishikawa, C.Y.; Huergo, L.F.; Monteiro, R.A.; Pedrosa, F.O.; Chubatsu, L.S.; Souza, E.M.

    2012-01-01

    Azospirillum brasilense is a diazotroph that associates with important agricultural crops and thus has potential to be a nitrogen biofertilizer. The A. brasilense transcription regulator NifA, which seems to be constitutively expressed, activates the transcription of nitrogen fixation genes. It has been suggested that the nitrogen status-signaling protein GlnB regulates NifA activity by direct interaction with the NifA N-terminal GAF domain, preventing the inhibitory effect of this domain under conditions of nitrogen fixation. In the present study, we show that an N-terminal truncated form of NifA no longer required GlnB for activity and lost regulation by ammonium. On the other hand, in trans co-expression of the N-terminal GAF domain inhibited the N-truncated protein in response to fixed nitrogen levels. We also used pull-down assays to show in vitro interaction between the purified N-terminal GAF domain of NifA and the GlnB protein. The results showed that A. brasilense GlnB interacts directly with the NifA N-terminal domain and this interaction is dependent on the presence of ATP and 2-oxoglutarate

  6. Effect of ATP and 2-oxoglutarate on the in vitro interaction between the NifA GAF domain and the GlnB protein of Azospirillum brasilense.

    Science.gov (United States)

    Sotomaior, P; Araújo, L M; Nishikawa, C Y; Huergo, L F; Monteiro, R A; Pedrosa, F O; Chubatsu, L S; Souza, E M

    2012-12-01

    Azospirillum brasilense is a diazotroph that associates with important agricultural crops and thus has potential to be a nitrogen biofertilizer. The A. brasilense transcription regulator NifA, which seems to be constitutively expressed, activates the transcription of nitrogen fixation genes. It has been suggested that the nitrogen status-signaling protein GlnB regulates NifA activity by direct interaction with the NifA N-terminal GAF domain, preventing the inhibitory effect of this domain under conditions of nitrogen fixation. In the present study, we show that an N-terminal truncated form of NifA no longer required GlnB for activity and lost regulation by ammonium. On the other hand, in trans co-expression of the N-terminal GAF domain inhibited the N-truncated protein in response to fixed nitrogen levels. We also used pull-down assays to show in vitro interaction between the purified N-terminal GAF domain of NifA and the GlnB protein. The results showed that A. brasilense GlnB interacts directly with the NifA N-terminal domain and this interaction is dependent on the presence of ATP and 2-oxoglutarate.

  7. Development of alginate-based aggregate inoculants of Methylobacterium sp. and Azospirillum brasilense tested under in vitro conditions to promote plant growth.

    Science.gov (United States)

    Joe, M M; Saravanan, V S; Islam, M R; Sa, T

    2014-02-01

    To develop co-aggregated bacterial inoculant comprising of Methylobacterium oryzae CBMB20/Methylobacterium suomiense CBMB120 strains with Azospirillum brasilense (CW903) strain and testing their efficiency as inoculants for plant growth promotion (PGP). Biofilm formation and co-aggregation efficiency was studied between A. brasilense CW903 and methylobacterial strains M. oryzae CBMB20 and M. suomiense CBMB120. Survival and release of these co-aggregated bacterial strains entrapped in alginate beads were assessed. PGP attributes of the co-aggregated bacterial inoculant were tested in tomato plants under water-stressed conditions. Results suggest that the biofilm formation efficiency of the CBMB20 and CBMB120 strains increased by 15 and 34%, respectively, when co-cultivated with CW903. Co-aggregation with CW903 enhanced the survivability of CBMB20 strain in alginate beads. Water stress index score showed least stress index in plants inoculated with CW903 and CBMB20 strains maintained as a co-aggregated inoculant. This study reports the development of co-aggregated cell inoculants containing M. oryzae CBMB20 and A. brasilense CW903 strains conferred better shelf life and stress abatement in inoculated tomato plants. These findings could be extended to other PGP bacterial species to develop multigeneric bioinoculants with multiple benefits for various crops. © 2013 The Society for Applied Microbiology.

  8. Characterization of cell surface and extracellular matrix remodeling of Azospirillum brasilense chemotaxis-like 1 signal transduction pathway mutants by atomic force microscopy.

    Science.gov (United States)

    Edwards, Amanda Nicole; Siuti, Piro; Bible, Amber N; Alexandre, Gladys; Retterer, Scott T; Doktycz, Mitchel J; Morrell-Falvey, Jennifer L

    2011-01-01

    To compete in complex microbial communities, bacteria must sense environmental changes and adjust cellular functions for optimal growth. Chemotaxis-like signal transduction pathways are implicated in the regulation of multiple behaviors in response to changes in the environment, including motility patterns, exopolysaccharide production, and cell-to-cell interactions. In Azospirillum brasilense, cell surface properties, including exopolysaccharide production, are thought to play a direct role in promoting flocculation. Recently, the Che1 chemotaxis-like pathway from A. brasilense was shown to modulate flocculation, suggesting an associated modulation of cell surface properties. Using atomic force microscopy, distinct changes in the surface morphology of flocculating A. brasilense Che1 mutant strains were detected. Whereas the wild-type strain produces a smooth mucosal extracellular matrix after 24 h, the flocculating Che1 mutant strains produce distinctive extracellular fibril structures. Further analyses using flocculation inhibition, lectin-binding assays, and comparison of lipopolysaccharides profiles suggest that the extracellular matrix differs between the cheA1 and the cheY1 mutants, despite an apparent similarity in the macroscopic floc structures. Collectively, these data indicate that disruption of the Che1 pathway is correlated with distinctive changes in the extracellular matrix, which likely result from changes in surface polysaccharides structure and/or composition. FEMS Microbiology Letters © 2010 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. No claim to original US government works.

  9. Characterization of cell surface and extracellular matrix remodeling of Azospirillum brasilense chemotaxis-like 1 signal transduction pathway mutants by atomic force microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Doktycz, Mitchel John [ORNL; Morrell-Falvey, Jennifer L [ORNL

    2011-01-01

    To compete in complex microbial communities, bacteria must sense environmental changes and adjust cellular functions for optimal growth. Chemotaxis-like signal transduction pathways are implicated in the regulation of multiple behaviors in response to changes in the environment, including motility patterns, exopolysaccharide production, and cell-to-cell interactions. In Azospirillum brasilense, cell surface properties, including exopolysaccharide production, are thought to play a direct role in promoting flocculation. Recently, the Che1 chemotaxis-like pathway from A. brasilense was shown to modulate flocculation, suggesting an associated modulation of cell surface properties. Using atomic force microscopy, distinct changes in the surface morphology of flocculating A. brasilense Che1 mutant strains were detected. Whereas the wild-type strain produces a smooth mucosal extracellular matrix after 24 h, the flocculating Che1 mutant strains produce distinctive extracellular fibril structures. Further analyses using flocculation inhibition, lectin-binding assays, and comparison of lipopolysaccharides profiles suggest that the extracellular matrix differs between the cheA1 and the cheY1 mutants, despite an apparent similarity in the macroscopic floc structures. Collectively, these data indicate that disruption of the Che1 pathway is correlated with distinctive changes in the extracellular matrix, which likely result from changes in surface polysaccharides structure and/or composition.

  10. Effect of ATP and 2-oxoglutarate on the in vitro interaction between the NifA GAF domain and the GlnB protein of Azospirillum brasilense

    Energy Technology Data Exchange (ETDEWEB)

    Sotomaior, P.; Araújo, L.M.; Nishikawa, C.Y.; Huergo, L.F.; Monteiro, R.A.; Pedrosa, F.O.; Chubatsu, L.S.; Souza, E.M. [Departamento de Bioquímica e Biologia Molecular, Universidade Federal do Paraná, Curitiba, PR (Brazil)

    2012-09-21

    Azospirillum brasilense is a diazotroph that associates with important agricultural crops and thus has potential to be a nitrogen biofertilizer. The A. brasilense transcription regulator NifA, which seems to be constitutively expressed, activates the transcription of nitrogen fixation genes. It has been suggested that the nitrogen status-signaling protein GlnB regulates NifA activity by direct interaction with the NifA N-terminal GAF domain, preventing the inhibitory effect of this domain under conditions of nitrogen fixation. In the present study, we show that an N-terminal truncated form of NifA no longer required GlnB for activity and lost regulation by ammonium. On the other hand, in trans co-expression of the N-terminal GAF domain inhibited the N-truncated protein in response to fixed nitrogen levels. We also used pull-down assays to show in vitro interaction between the purified N-terminal GAF domain of NifA and the GlnB protein. The results showed that A. brasilense GlnB interacts directly with the NifA N-terminal domain and this interaction is dependent on the presence of ATP and 2-oxoglutarate.

  11. Phytohormones and induction of plant-stress tolerance and defense genes by seed and foliar inoculation with Azospirillum brasilense cells and metabolites promote maize growth.

    Science.gov (United States)

    Fukami, Josiane; Ollero, Francisco Javier; Megías, Manuel; Hungria, Mariangela

    2017-12-01

    Azospirillum spp. are plant-growth-promoting bacteria used worldwide as inoculants for a variety of crops. Among the beneficial mechanisms associated with Azospirillum inoculation, emphasis has been given to the biological nitrogen fixation process and to the synthesis of phytohormones. In Brazil, the application of inoculants containing A. brasilense strains Ab-V5 and Ab-V6 to cereals is exponentially growing and in this study we investigated the effects of maize inoculation with these two strains applied on seeds or by leaf spray at the V2.5 stage growth-a strategy to relieve incompatibility with pesticides used for seed treatment. We also investigate the effects of spraying the metabolites of these two strains at V2.5. Maize growth was promoted by the inoculation of bacteria and their metabolites. When applied via foliar spray, although A. brasilense survival on leaves was confirmed by confocal microscopy and cell recovery, few cells were detected after 24 h, indicating that the effects of bacterial leaf spray might also be related to their metabolites. The major molecules detected in the supernatants of both strains were indole-3-acetic acid, indole-3-ethanol, indole-3-lactic acid and salicylic acid. RT-PCR of genes related to oxidative stress (APX1, APX2, CAT1, SOD2, SOD4) and plant defense (pathogenesis-related PR1, prp2 and prp4) was evaluated on maize leaves and roots. Differences were observed according to the gene, plant tissue, strain and method of application, but, in general, inoculation with Azospirillum resulted in up-regulation of oxidative stress genes in leaves and down-regulation in roots; contrarily, in general, PR genes were down-regulated in leaves and up-regulated in roots. Emphasis should be given to the application of metabolites, especially of Ab-V5 + Ab-V6 that in general resulted in the highest up-regulation of oxidative-stress and PR genes both in leaves and in roots. We hypothesize that the benefits of inoculation of Azospirillum on

  12. PRODUTIVIDADE DO TRIGO IRRIGADO SUBMETIDO À APLICAÇÃO DE NITROGÊNIO E À INOCULAÇÃO COM AZOSPIRILLUM BRASILENSE

    Directory of Open Access Journals (Sweden)

    Pedro Henrique Marques Paula Nunes

    2015-02-01

    Full Text Available Inocular sementes de trigo com Azospirillum brasilense pode ser benéfico à cultura do trigo, bem como reduzir a necessidade de aplicação de N. No entanto, são escassos trabalhos que mensurem o benefício dessa prática no trigo irrigado com expectativa de alta produtividade e demanda de N. Objetivou-se com este trabalho avaliar a produtividade e o conteúdo de N na planta do trigo irrigado, submetido a doses de N, com ou sem a inoculação com A. brasilense. Foram conduzidos dois experimentos em 2011 e repetidos em 2012. Em cada ano de cultivo, instalou-se um experimento na área considerada de baixa disponibilidade de N no solo (cultivo em sucessão ao milho e outro na com alta disponibilidade (cultivo em sucessão à soja ou cenoura. Os tratamentos consistiram de cinco doses de N e da inoculação ou não com A. brasilense. As doses de N testadas foram 20, 60, 100, 140 e 180 kg ha-1 na área com baixa disponibilidade de N e 20, 50, 80, 110 e 140 kg ha-1 na com alta disponibilidade. O teor de N na folha índice foi aumentado pela inoculação com A. brasilense. Entretanto, o N absorvido não foi influenciado pela inoculação da bactéria. As doses de N aumentaram a produtividade do trigo e esse aumento foi mais evidente no cultivo na área com baixa disponibilidade de N no solo.

  13. Gene encoding gamma-carbonic anhydrase is cotranscribed with argC and induced in response to stationary phase and high CO2 in Azospirillum brasilense Sp7.

    Science.gov (United States)

    Kaur, Simarjot; Mishra, Mukti N; Tripathi, Anil K

    2010-07-04

    Carbonic anhydrase (CA) is a ubiquitous enzyme catalyzing the reversible hydration of CO2 to bicarbonate, a reaction underlying diverse biochemical and physiological processes. Gamma class carbonic anhydrases (gamma-CAs) are widespread in prokaryotes but their physiological roles remain elusive. At present, only gamma-CA of Methanosarcina thermophila (Cam) has been shown to have CA activity. Genome analysis of a rhizobacterium Azospirillum brasilense, revealed occurrence of ORFs encoding one beta-CA and two gamma-CAs. One of the putative gamma-CA encoding genes of A. brasilense was cloned and overexpressed in E. coli. Electrometric assays for CA activity of the whole cell extracts overexpressing recombinant GCA1 did not show CO2 hydration activity. Reverse transcription-PCR analysis indicated that gca1 in A. brasilense is co-transcribed with its upstream gene annotated as argC, which encodes a putative N-acetyl-gamma-glutamate-phosphate reductase. 5'-RACE also demonstrated that there was no transcription start site between argC and gca1, and the transcription start site located upstream of argC transcribed both the genes (argC-gca1). Using transcriptional fusions of argC-gca1 upstream region with promoterless lacZ, we further demonstrated that gca1 upstream region did not have any promoter and its transcription occurred from a promoter located in the argC upstream region. The transcription of argC-gca1 operon was upregulated in stationary phase and at elevated CO2 atmosphere. This study shows lack of CO2 hydration activity in a recombinant protein expressed from a gene predicted to encode a gamma-carbonic anhydrase in A. brasilense although it cross reacts with anti-Cam antibody raised against a well characterized gamma-CA. The organization and regulation of this gene along with the putative argC gene suggests its involvement in arginine biosynthetic pathway instead of the predicted CO2 hydration.

  14. An extracytoplasmic function sigma factor cotranscribed with its cognate anti-sigma factor confers tolerance to NaCl, ethanol and methylene blue in Azospirillum brasilense Sp7.

    Science.gov (United States)

    Mishra, Mukti Nath; Kumar, Santosh; Gupta, Namrata; Kaur, Simarjot; Gupta, Ankush; Tripathi, Anil K

    2011-04-01

    Azospirillum brasilense, a plant-growth-promoting rhizobacterium, is exposed to changes in its abiotic environment, including fluctuations in temperature, salinity, osmolarity, oxygen concentration and nutrient concentration, in the rhizosphere and in the soil. Since extra-cytoplasmic function (ECF) sigma factors play an important role in stress adaptation, we analysed the role of ECF sigma factor (also known as RpoE or σ(E)) in abiotic stress tolerance in A. brasilense. An in-frame rpoE deletion mutant of A. brasilense Sp7 was carotenoidless and slow-growing, and was sensitive to salt, ethanol and methylene blue stress. Expression of rpoE in the rpoE deletion mutant complemented the defects in growth, carotenoid biosynthesis and sensitivity to different stresses. Based on data from reverse transcriptase-PCR, a two-hybrid assay and a pull-down assay, we present evidence that rpoE is cotranscribed with chrR and the proteins synthesized from these two overlapping genes interact with each other. Identification of the transcription start site by 5' rapid amplification of cDNA ends showed that the rpoE-chrR operon was transcribed by two promoters. The proximal promoter was less active than the distal promoter, whose consensus sequence was characteristic of RpoE-dependent promoters found in alphaproteobacteria. Whereas the proximal promoter was RpoE-independent and constitutively expressed, the distal promoter was RpoE-dependent and strongly induced in response to stationary phase and elevated levels of ethanol, salt, heat and methylene blue. This study shows the involvement of RpoE in controlling carotenoid synthesis as well as in tolerance to some abiotic stresses in A. brasilense, which might be critical in the adaptation, survival and proliferation of this rhizobacterium in the soil and rhizosphere under stressful conditions.

  15. Distinct Domains of CheA Confer Unique Functions in Chemotaxis and Cell Length in Azospirillum brasilense Sp7.

    Science.gov (United States)

    Gullett, Jessica M; Bible, Amber; Alexandre, Gladys

    2017-07-01

    Chemotaxis is the movement of cells in response to gradients of diverse chemical cues. Motile bacteria utilize a conserved chemotaxis signal transduction system to bias their motility and navigate through a gradient. A central regulator of chemotaxis is the histidine kinase CheA. This cytoplasmic protein interacts with membrane-bound receptors, which assemble into large polar arrays, to propagate the signal. In the alphaproteobacterium Azospirillum brasilense , Che1 controls transient increases in swimming speed during chemotaxis, but it also biases the cell length at division. However, the exact underlying molecular mechanisms for Che1-dependent control of multiple cellular behaviors are not known. Here, we identify specific domains of the CheA1 histidine kinase implicated in modulating each of these functions. We show that CheA1 is produced in two isoforms: a membrane-anchored isoform produced as a fusion with a conserved seven-transmembrane domain of unknown function (TMX) at the N terminus and a soluble isoform similar to prototypical CheA. Site-directed and deletion mutagenesis combined with behavioral assays confirm the role of CheA1 in chemotaxis and implicate the TMX domain in mediating changes in cell length. Fluorescence microscopy further reveals that the membrane-anchored isoform is distributed around the cell surface while the soluble isoform localizes at the cell poles. Together, the data provide a mechanism for the role of Che1 in controlling multiple unrelated cellular behaviors via acquisition of a new domain in CheA1 and production of distinct functional isoforms. IMPORTANCE Chemotaxis provides a significant competitive advantage to bacteria in the environment, and this function has been transferred laterally multiple times, with evidence of functional divergence in different genomic contexts. The molecular principles that underlie functional diversification of chemotaxis in various genomic contexts are unknown. Here, we provide a molecular

  16. Eficiência da inoculação de Azospirillum brasilense associado com enraizador no crescimento e na produção de alface

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    Antonio Anicete de Lima

    2017-06-01

    Full Text Available Objetivou-se avaliar o efeito da inoculação de Azospirillum brasilense (AzBr com e sem enraizador, no crescimento, produção de biomassa e resistência a pragas da alface, cultivar Lucy Brown. O experimento foi conduzido em casa de vegetação em recipientes plásticos com capacidade de 8,0 L no espaçamento 40 x 20 cm. O delineamento experimental foi de blocos casualizados em esquema fatorial (2x3+1, sendo o primeiro fator Azospirillum com e sem enraizador de crescimento e o segundo doses de nitrogênio em cobertura, 0%, 50% e 100% da recomendação de adubação e uma testemunha com adubação convencional, com quatro repetições. Em doses médias de 50% de N em cobertura, tanto o AzBr, quanto a associação AzBr mais enraizador, apresentaram um incremento significativo na massa fresca da parte aérea e de raízes de 19,36% e 23,66%, respectivamente, em relação a dose máxima de N e a testemunha. A massa seca da parte aérea não diferiu significativamente nos diferentes tratamentos, embora tenha mostrado um pequeno aumento com as doses crescente de N. A massa seca de raízes diminuiu 29,24% no tratamento com 100% de N, quando comparado ao tratamento sem cobertura nitrogenada mais AzBr. O estande final de plantas foi significativamente maior no tratamento no qual N não foi aplicado em cobertura, destacando-se a inoculação com AzBr, média de 96,98% de plantas estabelecidas, contra 51,56% na testemunha convencional, observando-se que até a dose média de N, houve uma maior tolerância das plantas aos sintomas de minas foliares e as viroses do Grupo Tospovirus.Azospirillum brasilense inoculation efficiency associated with rooting growth and production of lettuceAbstract: In the survey evaluated the effect of Azospirillum brasilense (AzBr inoculated with and without rooting, on growth, biomass production and lettuce pest resistance, cultivar Lucy Brown. The experiment was conducted in a greenhouse in plastic bags with 8.0 L capacity in

  17. Role of ethylene and related gene expression in the interaction between strawberry plants and the plant growth-promoting bacterium Azospirillum brasilense.

    Science.gov (United States)

    Elías, J M; Guerrero-Molina, M F; Martínez-Zamora, M G; Díaz-Ricci, J C; Pedraza, R O

    2018-05-01

    Induced systemic resistance (ISR) is one of the indirect mechanisms of growth promotion exerted by plant growth-promoting bacteria, and can be mediated by ethylene (ET). We assessed ET production and the expression of related genes in the Azospirillum-strawberry plant interaction. Ethylene production was evaluated by gas chromatography in plants inoculated or not with A. brasilense REC3. Also, plants were treated with AgNO 3 , an inhibitor of ET biosynthesis; with 1-aminocyclopropane-1-carboxylic acid (ACC), a precursor of ET biosynthesis; and with indole acetic acid (IAA). Plant dry biomass and the growth index were determined to assess the growth-promoting effect of A. brasilense REC3 in strawberry plants. Quantitative real time PCR (qRT-PCR) was performed to analyse relative expression of the genes Faetr1, Faers1 and Faein4, which encode ET receptors; Factr1 and Faein2, involved in the ET signalling pathway; Faacs1 encoding ACC synthase; Faaco1 encoding ACC oxidase; and Faaux1 and Faami1 for IAA synthesis enzymes. Results showed that ET acts as a rapid and transient signal in the first 12 h post-treatment. A. brasilense REC3-inoculated plants had a significantly higher growth index compared to control plants. Modulation of the genes Faetr1, Faers1, Faein4, Factr1, Faein2 and Faaco1 indicated activation of ET synthesis and signalling pathways. The up-regulation of Faaux1 and Faami1 involved in IAA synthesis suggested that inoculation with A. brasilense REC3 induces production of this auxin, modulating ET signalling. Ethylene production and up-regulation of genes associated with ET signalling in strawberry plants inoculated with A. brasilense REC3 support the priming activation characteristic of ISR. This type of resistance and the activation of systemic acquired resistance previously observed in this interaction indicate that both are present in strawberry plants, could act synergistically and increase protection against pathogens. © 2018 German Society

  18. A SAM-dependent methyltransferase cotranscribed with arsenate reductase alters resistance to peptidyl transferase center-binding antibiotics in Azospirillum brasilense Sp7.

    Science.gov (United States)

    Singh, Sudhir; Singh, Chhaya; Tripathi, Anil Kumar

    2014-05-01

    The genome of Azospirillum brasilense harbors a gene encoding S-adenosylmethionine-dependent methyltransferase, which is located downstream of an arsenate reductase gene. Both genes are cotranscribed and translationally coupled. When they were cloned and expressed individually in an arsenate-sensitive strain of Escherichia coli, arsenate reductase conferred tolerance to arsenate; however, methyltransferase failed to do so. Sequence analysis revealed that methyltransferase was more closely related to a PrmB-type N5-glutamine methyltransferase than to the arsenate detoxifying methyltransferase ArsM. Insertional inactivation of prmB gene in A. brasilense resulted in an increased sensitivity to chloramphenicol and resistance to tiamulin and clindamycin, which are known to bind at the peptidyl transferase center (PTC) in the ribosome. These observations suggested that the inability of prmB:km mutant to methylate L3 protein might alter hydrophobicity in the antibiotic-binding pocket of the PTC, which might affect the binding of chloramphenicol, clindamycin, and tiamulin differentially. This is the first report showing the role of PrmB-type N5-glutamine methyltransferases in conferring resistance to tiamulin and clindamycin in any bacterium.

  19. The ntrB and ntrC Genes Are Involved in the Regulation of Poly-3-Hydroxybutyrate Biosynthesis by Ammonia in Azospirillum brasilense Sp7

    Science.gov (United States)

    Sun, Jun; Peng, Xuan; Van Impe, Jan; Vanderleyden, Jos

    2000-01-01

    Azospirillum brasilense Sp7 and its ntrA (rpoN), ntrBC, and ntrC mutants have been evaluated for their capabilities of poly-3-hydroxybutyrate (PHB) accumulation in media with high and low ammonia concentrations. It was observed that the ntrBC and ntrC mutants can produce PHB in both low- and high-C/N-ratio media, while no significant PHB production was observed for the wild type or the ntrA mutant in low-C/N-ratio media. Further investigation by fermentation analysis indicated that the ntrBC and ntrC mutants were able to grow and accumulate PHB simultaneously in the presence of a high concentration of ammonia in the medium, while little PHB was produced in the wild type and ntrA (rpoN) mutant during active growth phase. These results provide the first genetic evidence that the ntrB and ntrC genes are involved in the regulation of PHB synthesis by ammonia in A. brasilense Sp7. PMID:10618211

  20. Evidence for ferritin as dominant iron-bearing species in the rhizobacterium Azospirillum brasilense Sp7 provided by low-temperature/in-field Mössbauer spectroscopy.

    Science.gov (United States)

    Kovács, Krisztina; Kamnev, Alexander A; Pechoušek, Jiří; Tugarova, Anna V; Kuzmann, Ernő; Machala, Libor; Zbořil, Radek; Homonnay, Zoltán; Lázár, Károly

    2016-02-01

    For the ubiquitous diazotrophic rhizobacterium Azospirillum brasilense, which has been attracting the attention of researchers worldwide for the last 35 years owing to its significant agrobiotechnological and phytostimulating potential, the data on iron acquisition and its chemical speciation in cells are scarce. In this work, for the first time for azospirilla, low-temperature (at 80 K, 5 K, as well as at 2 K without and with an external magnetic field of 5 T) transmission Mössbauer spectroscopic studies were performed for lyophilised biomass of A. brasilense (wild-type strain Sp7 grown with (57)Fe(III) nitrilotriacetate complex as the sole source of iron) to enable quantitative chemical speciation analysis of the intracellular iron. In the Mössbauer spectrum at 80 K, a broadened quadrupole doublet of high-spin iron(III) was observed with a few percent of a high-spin iron(II) contribution. In the spectrum measured at 5 K, a dominant magnetically split component appeared with the parameters typical of ferritin species from other bacteria, together with a quadrupole doublet of a superparamagnetic iron(III) component and a similarly small contribution from the high-spin iron(II) component. The Mössbauer spectra recorded at 2 K (with or without a 5 T external field) confirmed the assignment of ferritin species. About 20% of total Fe in the dry cells of A. brasilense strain Sp7 were present in iron(III) forms superparamagnetic at both 5 and 2 K, i.e. either different from ferritin cores or as ferritin components with very small particle sizes.

  1. A constitutively expressed pair of rpoE2-chrR2 in Azospirillum brasilense Sp7 is required for survival under antibiotic and oxidative stress.

    Science.gov (United States)

    Gupta, Namrata; Kumar, Santosh; Mishra, Mukti Nath; Tripathi, Anil Kumar

    2013-02-01

    Extracytoplasmic function (ECF) sigma factors (σ(E)) are known to bring about changes in gene expression to enable bacteria to adapt to different stresses. The Azospirillum brasilense Sp245 genome harbours nine genes encoding σ(E), of which two are adjacent to the genes encoding ChrR-type zinc-binding anti-sigma (ZAS) factors. We describe here the role and regulation of a new pair of rpoE-chrR, which was found in the genome of A. brasilense Sp7 in addition to the previously described rpoE-chrR pair (designated rpoE1-chrR1). The rpoE2-chrR2 pair is also cotranscribed, and their products show protein-protein interaction. The -10 and -35 promoter elements of rpoE2-chrR2 and rpoE1-chrR1 were similar but not identical. Unlike the promoter of rpoE1-chrR1, the rpoE2-chrR2 promoter was neither autoregulated nor induced by oxidative stress. Inactivation of chrR2 or overexpression of rpoE2 in A. brasilense Sp7 resulted in an overproduction of carotenoids. It also conferred resistance to oxidative stresses and antibiotics. By controlling the synthesis of carotenoids, initiation and elongation of translation, protein folding and purine biosynthesis, RpoE2 seems to play a crucial role in preventing and repairing the cellular damage caused by oxidative stress. Lack of autoregulation and constitutive expression of rpoE2-chrR2 suggest that RpoE2-ChrR2 may provide a rapid mechanism to cope with oxidative stress, wherein singlet oxygen ((1)O(2))-mediated dissociation of the RpoE2-ChrR2 complex might release RpoE2 to drive the expression of its target genes.

  2. Sequencing and promoter analysis of the nifENXorf3orf5fdxAnifQ operon from Azospirillum brasilense Sp7

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    Potrich D.P.

    2001-01-01

    Full Text Available A 40-kb DNA region containing the major cluster of nif genes has been isolated from the Azospirillum brasilense Sp7 genome. In this region three nif operons have been identified: nifHDKorf1Y, nifENXorf3orf5fdxAnifQ and orf2nifUSVorf4. The operons containing nifENX and nifUSV genes are separated from the structural nifHDKorf1Y operon by about 5 kb and 10 kb, respectively. The present study shows the sequence analysis of the 6045-bp DNA region containing the nifENX genes. The deduced amino acid sequences from the open reading frames were compared to the nif gene products of other diazotrophic bacteria and indicate the presence of seven ORFs, all reading in the same direction as that of the nifHDKorf1Y operon. Consensus sigma54 and NifA-binding sites are present only in the promoter region upstream of the nifE gene. This promoter is activated by NifA protein and is approximately two-times less active than the nifH promoter, as indicated by the ß-galactosidase assays. This result suggests the differential expression of the nif genes and their respective products in Azospirillum.

  3. Maize Inoculation with Azospirillum brasilense Ab-V5 Cells Enriched with Exopolysaccharides and Polyhydroxybutyrate Results in High Productivity under Low N Fertilizer Input

    Science.gov (United States)

    Oliveira, André L. M.; Santos, Odair J. A. P.; Marcelino, Paulo R. F.; Milani, Karina M. L.; Zuluaga, Mónica Y. A.; Zucareli, Claudemir; Gonçalves, Leandro S. A.

    2017-01-01

    Although Azospirillum strains used in commercial inoculant formulations presents diazotrophic activity, it has been reported that their ability to produce phytohormones plays a pivotal role in plant growth-promotion, leading to a general recommendation of its use in association with regular N-fertilizer doses. In addition, a high variability in the effectiveness of Azospirillum inoculants is still reported under field conditions, contributing to the adoption of the inoculation technology as an additional management practice rather than its use as an alternative practice to the use of chemical inputs in agriculture. To investigate whether the content of stress-resistance biopolymers would improve the viability and performance of Azospirillum inoculants when used as substitute of N-fertilizers, biomass of A. brasilense strain Ab-V5 enriched in exopolysaccharides (EPS) and polyhydroxybutirate (PHB) was produced using a new culture medium developed by factorial mixture design, and the effectiveness of resulting inoculants was evaluated under field conditions. The culture medium formulation extended the log phase of A. brasilense cultures, which presented higher cell counts and increased EPS and PHB contents than observed in the cultures grown in the OAB medium used as control. An inoculation trial with maize conducted under greenhouse conditions and using the biopolymers-enriched Ab-V5 cells demonstrated the importance of EPS and PHB to the long term bacterial viability in soil and to the effectiveness of inoculation. The effectiveness of liquid and peat inoculants prepared with Ab-V5 cells enriched with EPS and PHB was also evaluated under field conditions, using maize as target crop along different seasons, with the inoculants applied directly over seeds or at topdressing under limiting levels of N-fertilization. No additive effect on yield resulted from inoculation under high N fertilizer input, while inoculated plants grown under 80% reduction in N fertilizer

  4. Maize Inoculation with Azospirillum brasilense Ab-V5 Cells Enriched with Exopolysaccharides and Polyhydroxybutyrate Results in High Productivity under Low N Fertilizer Input

    Directory of Open Access Journals (Sweden)

    André L. M. Oliveira

    2017-09-01

    Full Text Available Although Azospirillum strains used in commercial inoculant formulations presents diazotrophic activity, it has been reported that their ability to produce phytohormones plays a pivotal role in plant growth-promotion, leading to a general recommendation of its use in association with regular N-fertilizer doses. In addition, a high variability in the effectiveness of Azospirillum inoculants is still reported under field conditions, contributing to the adoption of the inoculation technology as an additional management practice rather than its use as an alternative practice to the use of chemical inputs in agriculture. To investigate whether the content of stress-resistance biopolymers would improve the viability and performance of Azospirillum inoculants when used as substitute of N-fertilizers, biomass of A. brasilense strain Ab-V5 enriched in exopolysaccharides (EPS and polyhydroxybutirate (PHB was produced using a new culture medium developed by factorial mixture design, and the effectiveness of resulting inoculants was evaluated under field conditions. The culture medium formulation extended the log phase of A. brasilense cultures, which presented higher cell counts and increased EPS and PHB contents than observed in the cultures grown in the OAB medium used as control. An inoculation trial with maize conducted under greenhouse conditions and using the biopolymers-enriched Ab-V5 cells demonstrated the importance of EPS and PHB to the long term bacterial viability in soil and to the effectiveness of inoculation. The effectiveness of liquid and peat inoculants prepared with Ab-V5 cells enriched with EPS and PHB was also evaluated under field conditions, using maize as target crop along different seasons, with the inoculants applied directly over seeds or at topdressing under limiting levels of N-fertilization. No additive effect on yield resulted from inoculation under high N fertilizer input, while inoculated plants grown under 80% reduction in

  5. Regulation of a Glycerol-Induced Quinoprotein Alcohol Dehydrogenase by σ54 and a LuxR-Type Regulator in Azospirillum brasilense Sp7.

    Science.gov (United States)

    Singh, Vijay Shankar; Dubey, Ashutosh Prakash; Gupta, Ankush; Singh, Sudhir; Singh, Bhupendra Narain; Tripathi, Anil Kumar

    2017-07-01

    Azospirillum brasilense Sp7 uses glycerol as a carbon source for growth and nitrogen fixation. When grown in medium containing glycerol as a source of carbon, it upregulates the expression of a protein which was identified as quinoprotein alcohol dehydrogenase (ExaA). Inactivation of exaA adversely affects the growth of A. brasilense on glycerol. A determination of the transcription start site of exaA revealed an RpoN-dependent -12/-24 promoter consensus. The expression of an exaA :: lacZ fusion was induced maximally by glycerol and was dependent on σ 54 Bioinformatic analysis of the sequence flanking the -12/-24 promoter revealed a 17-bp sequence motif with a dyad symmetry of 6 nucleotides upstream of the promoter, the disruption of which caused a drastic reduction in promoter activity. The electrophoretic mobility of a DNA fragment containing the 17-bp sequence motif was retarded by purified EraR, a LuxR-type transcription regulator that is transcribed divergently from exaA EraR also showed a positive interaction with RpoN in two-hybrid and pulldown assays. IMPORTANCE Quinoprotein alcohol dehydrogenase (ExaA) plays an important role in the catabolism of alcohols in bacteria. Although exaA expression is thought to be regulated by a two-component system consisting of EraS and EraR, the mechanism of regulation was not known. This study shows the details of the regulation of expression of the exaA gene in A. brasilense We have shown here that exaA of A. brasilense is maximally induced by glycerol and harbors a σ 54 -dependent promoter. The response regulator EraR binds to an inverted repeat located upstream of the exaA promoter. This study shows that a LuxR-type response regulator (EraR) binds upstream of the exaA gene and physically interacts with σ 54 The unique feature of this regulation is that EraR is a LuxR-type transcription regulator that lacks the GAFTGA motif, a characteristic feature of the enhancer binding proteins that are known to interact with σ 54

  6. Gene encoding γ-carbonic anhydrase is cotranscribed with argC and induced in response to stationary phase and high CO2 in Azospirillum brasilense Sp7

    Science.gov (United States)

    2010-01-01

    Background Carbonic anhydrase (CA) is a ubiquitous enzyme catalyzing the reversible hydration of CO2 to bicarbonate, a reaction underlying diverse biochemical and physiological processes. Gamma class carbonic anhydrases (γ-CAs) are widespread in prokaryotes but their physiological roles remain elusive. At present, only γ-CA of Methanosarcina thermophila (Cam) has been shown to have CA activity. Genome analysis of a rhizobacterium Azospirillum brasilense, revealed occurrence of ORFs encoding one β-CA and two γ-CAs. Results One of the putative γ-CA encoding genes of A. brasilense was cloned and overexpressed in E. coli. Electrometric assays for CA activity of the whole cell extracts overexpressing recombinant GCA1 did not show CO2 hydration activity. Reverse transcription-PCR analysis indicated that gca1 in A. brasilense is co-transcribed with its upstream gene annotated as argC, which encodes a putative N-acetyl-γ-glutamate-phosphate reductase. 5'-RACE also demonstrated that there was no transcription start site between argC and gca1, and the transcription start site located upstream of argC transcribed both the genes (argC-gca1). Using transcriptional fusions of argC-gca1 upstream region with promoterless lacZ, we further demonstrated that gca1 upstream region did not have any promoter and its transcription occurred from a promoter located in the argC upstream region. The transcription of argC-gca1 operon was upregulated in stationary phase and at elevated CO2 atmosphere. Conclusions This study shows lack of CO2 hydration activity in a recombinant protein expressed from a gene predicted to encode a γ-carbonic anhydrase in A. brasilense although it cross reacts with anti-Cam antibody raised against a well characterized γ-CA. The organization and regulation of this gene along with the putative argC gene suggests its involvement in arginine biosynthetic pathway instead of the predicted CO2 hydration. PMID:20598158

  7. Gene encoding γ-carbonic anhydrase is cotranscribed with argC and induced in response to stationary phase and high CO2 in Azospirillum brasilense Sp7

    Directory of Open Access Journals (Sweden)

    Mishra Mukti N

    2010-07-01

    Full Text Available Abstract Background Carbonic anhydrase (CA is a ubiquitous enzyme catalyzing the reversible hydration of CO2 to bicarbonate, a reaction underlying diverse biochemical and physiological processes. Gamma class carbonic anhydrases (γ-CAs are widespread in prokaryotes but their physiological roles remain elusive. At present, only γ-CA of Methanosarcina thermophila (Cam has been shown to have CA activity. Genome analysis of a rhizobacterium Azospirillum brasilense, revealed occurrence of ORFs encoding one β-CA and two γ-CAs. Results One of the putative γ-CA encoding genes of A. brasilense was cloned and overexpressed in E. coli. Electrometric assays for CA activity of the whole cell extracts overexpressing recombinant GCA1 did not show CO2 hydration activity. Reverse transcription-PCR analysis indicated that gca1 in A. brasilense is co-transcribed with its upstream gene annotated as argC, which encodes a putative N-acetyl-γ-glutamate-phosphate reductase. 5'-RACE also demonstrated that there was no transcription start site between argC and gca1, and the transcription start site located upstream of argC transcribed both the genes (argC-gca1. Using transcriptional fusions of argC-gca1 upstream region with promoterless lacZ, we further demonstrated that gca1 upstream region did not have any promoter and its transcription occurred from a promoter located in the argC upstream region. The transcription of argC-gca1 operon was upregulated in stationary phase and at elevated CO2 atmosphere. Conclusions This study shows lack of CO2 hydration activity in a recombinant protein expressed from a gene predicted to encode a γ-carbonic anhydrase in A. brasilense although it cross reacts with anti-Cam antibody raised against a well characterized γ-CA. The organization and regulation of this gene along with the putative argC gene suggests its involvement in arginine biosynthetic pathway instead of the predicted CO2 hydration.

  8. AZOSPIRILLUM BRASILENSE VIA FOLIAR E DOSES DE NITROGÊNIO EM COBERTURA NA CULTURA DO TRIGO NA REGIÃO DE ITAPEVA-SP / SPRAYING WITH AZOSPIRILLUM ON WHEAT LEAF AND NITROGEN COVERAGE RATES IN ITAPEVA-SP

    Directory of Open Access Journals (Sweden)

    J. P. Ferreira

    2017-06-01

    Full Text Available A utilização de bactérias diazotróficas na agricultura, especialmente em gramíneas, tem por finalidade incrementar a produção e produtividade aliando com menor dose ou supressão das fontes nitrogenadas aplicadas para fertilização do solo. Diante disso, o trabalho objetivou avaliar a viabilidade da inoculação de Azospirillum brasilense via foliar com doses de nitrogênio em cobertura na produção e produtividade do trigo. O experimento foi implantado na Fazenda Bom Viver, Bairro dos Prestes em Itapeva-SP, na safra de 2016, sendo realizado em plantio direto (SPC em área de sucessão soja e milho safrinha. Os tratamentos foram em esquema fatorial 2x4 em blocos ao acaso (DBC sendo aplicado a formulação liquida de Azospirillum brasiliense (AbV5 com 2x108 células viáveis mL-1 na dose de 0,5 L.ha-1 via foliar e sem aplicação e posterior adubação nitrogenada com 0; 30; 60 e 90 kg.ha-1 em cobertura. Tanto a aplicação foliar de Azospirillum como a cobertura de N, foram aplicadas após 30 dias da semeadura (30 DAS. A variedade de trigo utilizada no plantio foi o Sinuelo, com manejo adotado pelo proprietário da área com aplicação de regulador de crescimento. Foram realizadas as avaliações a campo das plantas, medindo-se: a altura das plantas; espigas por metro linear; número de grãos por espiguetas; peso hectolítro; massa de mil grãos e produtividade. Pelos resultados obtidos, houve maior altura de plantas com o aumento das doses de nitrogênio em cobertura. A inoculação de Azospirillum brasiliense via foliar não mostrou interação entre as doses de nitrogênio em cobertura, não havendo estatisticamente incremento nos componentes de produtividade do trigo.

  9. Nitrogen uptake by Azospirillum brasilense inoculated barley (Hordeum vulgare L.) as influenced by N and P fertilization

    International Nuclear Information System (INIS)

    Negi, Mahima; Tilak, K.V.B.R.; Sachdev, M.S.

    1991-01-01

    Response of barley (Hordeum vulgare L.) in a sandy-loam soil under potted conditions revealed that application of nitrogen and phosphorus increased the population of Azospirillium in the barley rhizosphere. A two fold increase was observed in the Azospirillium population at 80 days compared to that at 40 days of plant growth. The unsterilized inoculated roots had more population than the surface sterilized inoculated roots. Increased drymatter production of barley was obtained in A. brasilense inoculated N 0 P 1 (0 kg N and 30 kg P 2 O 5 ha -1 ) treatment than uninoculated control. Also N and P uptake was higher in A. brasilense inoculated plants in the presence of both N and P fertilizers. The 15 N data revealed that at harvest nearly 36 per cent of the total N uptake was from the nitrogen fixed by A. brasilense irrespective of P treatment. (author). 16 refs., 4 tabs

  10. FTIR spectroscopic studies of selenite reduction by cells of the rhizobacterium Azospirillum brasilense Sp7 and the formation of selenium nanoparticles

    Science.gov (United States)

    Kamnev, Alexander A.; Mamchenkova, Polina V.; Dyatlova, Yulia A.; Tugarova, Anna V.

    2017-07-01

    Microbially driven reduction of selenium oxyanions to elementary selenium, often in the form of nanoparticles (NPs), is widespread in nature. A diversity of possible applications of such biogenic NPs, including those in nanobiotechnology, as well as the specificity of methodologies and mechanisms of their formation via ;green synthesis; are very attractive features justifying further studies of the processes of selenium oxyanion bioreduction and the resulting Se0 nanostructures. In this study, live biomass of the rhizobacterium Azospirillum brasilense Sp7 (harvested after the logarithmic growth phase and washed from culture medium components) was used to obtain extracellular Se NPs relatively homogeneous in size (with average diameters within 50-100 nm) in the process of selenite reduction. Both the control cultures of A. brasilense Sp7 and those incubated with SeO32- (producing Se NPs), as well as the resulting separated Se NPs were studied using Fourier transform infrared (FTIR) spectroscopy in the transmission mode (measured as dried layers on a ZnSe disc), in addition to transmission electron microscopy (TEM), to compare metabolic changes in cells and the bioorganic layers associated with the Se NPs. In the control culture (stored for 24 h in physiological saline), FTIR spectroscopic signs of poly-3-hydroxybutyrate (a 'reserve' biopolyester) were observed as a response to the lack of nutrients (trophic stress), whereas they were virtually absent in cells incubated for 24 h in physiological saline with 10 mM SeO32- (toxicity stress). FTIR spectra of Se NPs separated from bacterial cells showed bands typical of proteins, polysaccharides and lipids associated with the particles (in line with their TEM images showing a thin layer over the NPs), in addition to strong carboxylate bands, which evidently stabilise the NP structure and morphology.

  11. Adubação nitrogenada associada à inoculação com Azospirillum brasilense e Herbaspirillum seropedicae na cultura do milho

    Directory of Open Access Journals (Sweden)

    Janaína Dartora

    2013-10-01

    Full Text Available Bactérias dos gêneros Azospirillum e Herbaspirillum são fixadoras de nitrogênio (N atmosférico e consideradas promotoras do crescimento vegetal. Desta forma, desenvolveu-se o presente trabalho com o objetivo de avaliar o desenvolvimento e a produtividade do milho em resposta à inoculação de A. brasilense e H. seropedicae associada à adubação nitrogenada. O experimento foi conduzido em delineamento experimental de blocos ao acaso em esquema fatorial 4 x 5, com quatro repetições. Os tratamentos foram constituídos da inoculação de sementes (testemunha, estirpe de A. brasilense - Ab-V5, estirpe de H. seropedicae - SmR1 e combinação Ab-V5 + SmR1 e doses de N (0, 40, 80, 120 e 160 kg ha-1 de N. Foram avaliados: diâmetro basal do colmo, altura de planta, matéria seca de parte aérea e área foliar, nas fases vegetativa e reprodutiva, e produtividade. A adubação nitrogenada favoreceu o desenvolvimento da cultura até a máxima dose estudada. A inoculação combinada das estirpes proporcionou incrementos de 12% na matéria seca de parte aérea e 7% na produtividade em relação à testemunha indicando benefícios da combinação de bactérias diazotróficas que interagem de forma diferenciada com a planta.

  12. Chromosomal flhB1 gene of the alphaproteobacterium Azospirillum brasilense Sp245 is essential for correct assembly of both constitutive polar flagellum and inducible lateral flagella.

    Science.gov (United States)

    Filip'echeva, Yulia; Shelud'ko, Andrei; Prilipov, Alexei; Telesheva, Elizaveta; Mokeev, Dmitry; Burov, Andrei; Petrova, Lilia; Katsy, Elena

    2018-03-01

    Azospirillum brasilense has the ability of swimming and swarming motility owing to the work of a constitutive polar flagellum and inducible lateral flagella, respectively. The interplay between these flagellar systems is poorly understood. One of the key elements of the flagellar export apparatus is the protein FlhB. Two predicted flhB genes are present in the genome of A. brasilense Sp245 (accession nos. HE577327-HE577333). Experimental evidence obtained here indicates that the chromosomal coding sequence (CDS) AZOBR_150177 (flhB1) of Sp245 is essential for the production of both types of flagella. In an flhB1:: Omegon-Km mutant, Sp245.1063, defects in polar and lateral flagellar assembly and motility were complemented by expressing the wild-type flhB1 gene from plasmid pRK415. It was found that Sp245.1063 lost the capacity for slight but statistically significant decrease in mean cell length in response to transfer from solid to liquid media, and vice versa; in the complemented mutant, this capacity was restored. It was also shown that after the acquisition of the pRK415-harbored downstream CDS AZOBR_150176, cells of Sp245 and Sp245.1063 ceased to elongate on solid media. These initial data suggest that the AZOBR_150176-encoded putative multisensory hybrid sensor histidine kinase-response regulator, in concert with FlhB1, plays a role in morphological response of azospirilla to changes in the hardness of a milieu.

  13. Efecto de la temperatura y el pH en la producción de biomasa de Azospirillum brasilense C16 aislada de pasto guinea

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    F Romero-Perdomo

    Full Text Available El objetivo del estudio fue evaluar el efecto de la temperatura y el pH en la viabilidad celular de la cepa Azospirillum brasilense C16. Se estudiaron cinco temperaturas (entre 28 y 36°C y cinco pH (de 4,5 a 8,5. El efecto de la temperatura se evaluó mediante la medición del crecimiento radial (mm de la cepa, sobre un papel de filtro en medio batata. En el caso del pH se utilizó un fermentador de tanque agitado -con una configuración tipo Rushton- para cuantificar la velocidad de crecimiento, la producción de biomasa y el tiempo de duplicación de la cepa; las condiciones de fermentación fueron: 400 rpm, 1 Lpm y 30°C, durante 24 horas. El pH y la temperatura influyeron significativamente (p < 0,05 en la producción de A. brasilense C16. La temperatura de 30°C fue la más favorable para que se multiplicara la cepa, con 23,21 mm de crecimiento radial; mientras que la mayor o igual a 34°C inhibió su crecimiento. Los mejores resultados se obtuvieron con un pH de 6,8, con diferencias significativas (p < 0,05 respecto al resto. Con esta condición se obtuvieron los valores más altos de velocidad de crecimiento (1,79 h-1 y producción de biomasa (8,65 log10 UFC mL-1, y el valor más bajo del tiempo de duplicación (1,09 h-1. Estos resultados poseen aplicabilidad biotecnológica, y son de gran importancia en el momento de definir y controlar las condiciones de producción masiva de biomasa de A. brasilense C16 para futuras formulaciones como biofertilizante en diversos cultivos de interés en Colombia.

  14. Chemical composition and deoxynivalenol in wheat of Central- Southern Paraná: nitrogen fertilization in top dressing associated with Azospirillum brasilense

    Directory of Open Access Journals (Sweden)

    Thiago Montagner Souza

    2014-02-01

    Full Text Available The impact of agricultural management practices on the quality of grain was evaluated in wheat (Triticum aestivum L. BRS Tangará from the South Central region of Paraná State (Ponta Grossa in the crop years of 2010 and 2011. The field trial was carried out in succession with soybean (2010 and corn (2011. The treatments included inoculation of seeds with Azospirillum brasilense and increasing levels of nitrogen application in top dressing (0, 30, 60, 90 and 120 kg ha-1. The experimental design was in randomized block, factorial 2 x 5 (inoculation x N levels, with four replications. The parameters evaluated were water activity, moisture, protein, and grain contamination by deoxynivalenol (DON. The data were subjected to analysis of variance, comparison of means by Tukey’s test (p<0.05 and regression for nitrogen levels. The inoculation of seeds with A. brasilense increased the protein content in grain in 2010 (+1.6%; 16.9 g 100g-1 and 2011 (+1.7%, 15.7 g 100g-1, independently of the nitrogen level (p<0.01. Levels of nitrogen in 2010 presented a positive linear response with protein content, increasing by 14.2% using non-inoculated seeds (p<0.01, R2=0.955 and 14.4% for those inoculated with A. brasilense (p<0.01, R2=0.906. However, in 2011 a quadratic response was observed between nitrogen levels and protein content (p<0.01, R2=0.99, with stabilization or reduction in protein content using high levels of nitrogen (?120 kg ha-1. The contamination by DON was greater using high levels of nitrogen (3574 ?g kg-1, 120 kg ha-1; non-inoculated seeds in 2011, with a quadratic response between nitrogen levels and contamination of grains (p<0.05, R2=0.772. Furthermore, 37.5% of the samples presented contamination by DON higher than the maximum tolerated limit established by Brazilian legislation (2000 ?g kg-1; whole-wheat grain. The data demonstrates that proper management of nitrogen enhances intrinsic effects arising from plant breeding.

  15. Cross-talk between cognate and noncognate RpoE sigma factors and Zn(2+)-binding anti-sigma factors regulates photooxidative stress response in Azospirillum brasilense.

    Science.gov (United States)

    Gupta, Namrata; Gupta, Ankush; Kumar, Santosh; Mishra, Rajeev; Singh, Chhaya; Tripathi, Anil Kumar

    2014-01-01

    Azospirillum brasilense harbors two redox-sensitive Zinc-binding anti-sigma (ZAS) factors (ChrR1 and ChrR2), which negatively regulate the activity of their cognate extra-cytoplasmic function (ECF) σ factors (RpoE1 and RpoE2) by occluding their binding to the core enzyme. Both pairs of RpoE-ChrR control responses to photooxidative stress. The aim of this study was to investigate whether the two RpoE-ChrR pairs cross-talk while responding to the stress. In silico analysis showed a high sequence similarity between ChrR1 and ChrR2 proteins, but differences in redox sensitivity. Using in silico and in vitro methods of protein-protein interaction, we have shown that both ChrR1 and ChrR2 proteins physically bind to their noncognate RpoE proteins. Restoration of the phenotypes of chrR1::Tn5 and chrR2::Km mutants related to carotenoid biosynthesis and photooxidative stress tolerance by expressing chrR1 or chrR2 provided in vivo evidence for the cross-talk. In addition, up- or down-regulation of several identical proteins by expressing chrR1 or chrR2 in the chrR1::Tn5 mutant provided another in vivo evidence for the cross-talk. Although multiple redox-sensitive ZAS anti-σ factors occur in some Gram-positive bacteria, no cross-talk is reported among them. We report here, for the first time, that the two ZAS anti-σ factors of A. brasilense also interact with their noncognate σ factors and affect gene expression. The two redox-sensitive ZAS anti-σ factors in A. brasilense may interact with their cognate as well as noncognate ECF σ factors to play an important role in redox homeostasis by facilitating recovery from the oxidative stress.

  16. Optogenetic Manipulation of Cyclic Di-GMP (c-di-GMP) Levels Reveals the Role of c-di-GMP in Regulating Aerotaxis Receptor Activity in Azospirillum brasilense.

    Science.gov (United States)

    O'Neal, Lindsey; Ryu, Min-Hyung; Gomelsky, Mark; Alexandre, Gladys

    2017-09-15

    Bacterial chemotaxis receptors provide the sensory inputs that inform the direction of navigation in changing environments. Recently, we described the bacterial second messenger cyclic di-GMP (c-di-GMP) as a novel regulator of a subclass of chemotaxis receptors. In Azospirillum brasilense , c-di-GMP binds to a chemotaxis receptor, Tlp1, and modulates its signaling function during aerotaxis. Here, we further characterize the role of c-di-GMP in aerotaxis using a novel dichromatic optogenetic system engineered for manipulating intracellular c-di-GMP levels in real time. This system comprises a red/near-infrared-light-regulated diguanylate cyclase and a blue-light-regulated c-di-GMP phosphodiesterase. It allows the generation of transient changes in intracellular c-di-GMP concentrations within seconds of irradiation with appropriate light, which is compatible with the time scale of chemotaxis signaling. We provide experimental evidence that binding of c-di-GMP to the Tlp1 receptor activates its signaling function during aerotaxis, which supports the role of transient changes in c-di-GMP levels as a means of adjusting the response of A. brasilense to oxygen gradients. We also show that intracellular c-di-GMP levels in A. brasilense change with carbon metabolism. Our data support a model whereby c-di-GMP functions to imprint chemotaxis receptors with a record of recent metabolic experience, to adjust their contribution to the signaling output, thus allowing the cells to continually fine-tune chemotaxis sensory perception to their metabolic state. IMPORTANCE Motile bacteria use chemotaxis to change swimming direction in response to changes in environmental conditions. Chemotaxis receptors sense environmental signals and relay sensory information to the chemotaxis machinery, which ultimately controls the swimming pattern of cells. In bacteria studied to date, differential methylation has been known as a mechanism to control the activity of chemotaxis receptors and

  17. Fourier transform infrared spectroscopic characterisation of heavy metal-induced metabolic changes in the plant-associated soil bacterium Azospirillum brasilense Sp7

    Science.gov (United States)

    Kamnev, A. A.; Antonyuk, L. P.; Tugarova, A. V.; Tarantilis, P. A.; Polissiou, M. G.; Gardiner, P. H. E.

    2002-06-01

    Structural and compositional features of whole cells of the plant-growth-promoting rhizobacterium Azospirillum brasilense Sp7 under standard and heavy metal-stressed conditions are analysed using Fourier transform infrared (FTIR) spectroscopy and compared with the FT-Raman spectroscopic data obtained previously [J. Mol. Struct. 563-564 (2001) 199]. The structural spectroscopic information is considered together with inductively coupled plasma-mass spectrometric (ICP-MS) analytical data on the content of the heavy metal cations (Co2+, Cu2+ and Zn2+) in the bacterial cells. As a bacterial response to heavy metal stress, all the three metals, being taken up by bacterial cells from the culture medium (0.2 mM) in significant amounts (ca. 0.12, 0.48 and 4.2 mg per gram of dry biomass for Co, Cu and Zn, respectively), are shown to induce essential metabolic changes in the bacterium revealed in the spectra, including the accumulation of polyester compounds in bacterial cells and their enhanced hydration affecting certain IR vibrational modes of functional groups involved.

  18. Enhanced performance of the microalga Chlorella sorokiniana remotely induced by the plant growth-promoting bacteria Azospirillum brasilense and Bacillus pumilus

    Science.gov (United States)

    Amavizca, Edgar; Bashan, Yoav; Ryu, Choong-Min; Farag, Mohamed A.; Bebout, Brad M.; de-Bashan, Luz E.

    2017-01-01

    Remote effects (occurring without physical contact) of two plant growth-promoting bacteria (PGPB) Azospirillum brasilense Cd and Bacilus pumilus ES4 on growth of the green microalga Chlorella sorokiniana UTEX 2714 were studied. The two PGPB remotely enhanced the growth of the microalga, up to six-fold, and its cell volume by about three-fold. In addition to phenotypic changes, both bacteria remotely induced increases in the amounts of total lipids, total carbohydrates, and chlorophyll a in the cells of the microalga, indicating an alteration of the microalga’s physiology. The two bacteria produced large amounts of volatile compounds, including CO2, and the known plant growth-promoting volatile 2,3-butanediol and acetoin. Several other volatiles having biological functions in other organisms, as well as numerous volatile compounds with undefined biological roles, were detected. Together, these bacteria-derived volatiles can positively affect growth and metabolic parameters in green microalgae without physical attachment of the bacteria to the microalgae. This is a new paradigm on how PGPB promote growth of microalgae which may serve to improve performance of Chlorella spp. for biotechnological applications. PMID:28145473

  19. Positive effect of reduced aeration rate on growth and stereospecificity of DL-malic acid consumption by Azospirillum brasilense: improving the shelf life of a liquid inoculant formulation.

    Science.gov (United States)

    Carrasco-Espinosa, Karen; García-Cabrera, Ramsés I; Bedoya-López, Andrea; Trujillo-Roldán, Mauricio A; Valdez-Cruz, Norma A

    2015-02-10

    Azospirillum brasilense has significance as a growth promoter in plants of commercial interest. Two industrial native strains (Start and Calf), used as a part of an inoculant formulation in Mexico during the last 15 years, were incubated in laboratory-scale pneumatic bioreactors at different aeration rates. In both strains, the positive effect of decreased aeration was observed. At the lowest (0.1 vvm, air volume/liquid volume×minute), the highest biomass were obtained for Calf (7.8 × 10(10)CFU/ml), and Start (2.9 × 10(9)CFU/ml). These were higher in one magnitude order compared to cultures carried out at 0.5 vvm, and two compared to those at 1.0 vvm. At lower aeration, both stereoisomeric forms of malic acid were consumed, but at higher aeration, just L-malate was consumed. A reduction in aeration allows an increase of the shelf life and the microorganism saved higher concentrations of polyhydroxybutyrate. The selected fermentation conditions are closely related to those prevalent in large-scale bioreactors and offer the possibility of achieving high biomass titles with high shelf life at a reduced costs, due to the complete use of a carbon source at low aeration of a low cost raw material as DL-malic acid mixture in comparison with the L-malic acid stereoisomer. Copyright © 2015 Elsevier B.V. All rights reserved.

  20. [Changes in Cell Surface Properties and Biofilm Formation Efficiency in Azospirillum brasilense Sp245 Mutants in the Putative Genes of Lipid Metabolism mmsB1 and fabG1].

    Science.gov (United States)

    Shumilova, E; Shelud'ko, A V; Filip'echeva, Yu A; Evstigneeva, S S; Ponomareva, E G; Petrova, L P; Katsy, E I

    2016-01-01

    The previously obtained insertion mutants ofAzospirillum brasilense Sp245 in the genes mmsBl and fabG1 (strains SK039 and Sp245.1610, respectively) were characterized by impaired flagellation and motility. The putative products of expression of these genes are 3-hydroxyisobutyrate dehydrogenase and 3-oxoacyl-[acyl-carrier protein] reductase, respectively. In the present work, A. brasilense- Sp245 strains SK039 and Sp245.1610 were found to have differences in the content of 3-hydroxyhexadecanoic, hexadecanoic, 3-hydroxytetradecanoic, hexadecenoic, octadecenoic, and nonadecanoic acids in their lipopolysaccharide prepa- rations, as well as in cell hydrophobicity and hemagglutination activity and dynamics of cell aggregation, in biomass amount, and in the relative content of lipopolysaccharide antigens in mature biofilms formed on hydrophilic or hydrophobic surfaces.

  1. Coberturas vegetais, doses de nitrogênio e inoculação de sementes com Azospirillum brasilense em arroz de terras altas no sistema plantio direto

    Directory of Open Access Journals (Sweden)

    Douglas de Castilho Gitti

    2012-01-01

    Full Text Available O arroz é importante fonte de energia e proteínas para a população mundial, principalmente na Ásia e Oceania. No Brasil, juntamente com o feijão, constitui a base da alimentação. Tecnologias sustentáveis que reduzam custos da produção e aumentem a produtividade do arroz podem garantir seu suprimento em períodos de alta demanda. O objetivo deste trabalho foi avaliar diferentes coberturas vegetais antecessoras (milheto [Pennisetum americanum], crotalária [Crotalaria juncea], guandu [Cajanus cajan], braquiária [Brachiaria ruziziensis], milheto + crotalária e milheto + guandu, doses de nitrogênio (N em cobertura (0, 40, 80 e 120 kg ha-1 e o efeito da inoculação de sementes com Azospirillum brasilense no arroz de terras altas em sistema plantio direto no desenvolvimento e na produtividade. Utilizou-se o delineamento experimental em blocos casualizados em esquema fatorial 6x4x2 com quatro repetições. O estudo foi desenvolvido em um Latossolo Vermelho, em Selvíria, Estado do Mato Grosso do Sul, Brasil, em 2011/2012. O cultivo do guandu antecedendo o arroz proporcionou maior produtividade do arroz somente em comparação a B. ruziziensi. A produtividade do arroz em função das doses de N em cobertura se ajustou a uma função quadrática. Não houve influência da inoculação de sementes com A. brasilense sobre a produtividade do arroz, porém houve interação entre a inoculação e as coberturas vegetais sobre o teor de N foliar, número de panículas por m², matéria seca de plantas de arroz e a massa de cem grãos.

  2. Coberturas vegetais, doses de nitrogênio e inoculação de sementes com Azospirillum brasilense em arroz de terras altas no sistema plantio direto Cover crops, nitrogen rates and seeds inoculation with Azospirillum brasilense in upland rice under no-tillage

    Directory of Open Access Journals (Sweden)

    Douglas de Castilho Gitti

    2013-01-01

    Full Text Available O arroz é importante fonte de energia e proteínas para a população mundial, principalmente na Ásia e Oceania. No Brasil, juntamente com o feijão, constitui a base da alimentação. Tecnologias sustentáveis que reduzam custos da produção e aumentem a produtividade do arroz podem garantir seu suprimento em períodos de alta demanda. O objetivo deste trabalho foi avaliar diferentes coberturas vegetais antecessoras (milheto [Pennisetum americanum], crotalária [Crotalaria juncea], guandu [Cajanus cajan], braquiária [Brachiaria ruziziensis], milheto + crotalária e milheto + guandu, doses de nitrogênio (N em cobertura (0, 40, 80 e 120 kg ha-1 e o efeito da inoculação de sementes com Azospirillum brasilense no arroz de terras altas em sistema plantio direto no desenvolvimento e na produtividade. Utilizou-se o delineamento experimental em blocos casualizados em esquema fatorial 6x4x2 com quatro repetições. O estudo foi desenvolvido em um Latossolo Vermelho, em Selvíria, Estado do Mato Grosso do Sul, Brasil, em 2011/2012. O cultivo do guandu antecedendo o arroz proporcionou maior produtividade do arroz somente em comparação a B. ruziziensi. A produtividade do arroz em função das doses de N em cobertura se ajustou a uma função quadrática. Não houve influência da inoculação de sementes com A. brasilense sobre a produtividade do arroz, porém houve interação entre a inoculação e as coberturas vegetais sobre o teor de N foliar, número de panículas por m², matéria seca de plantas de arroz e a massa de cem grãos.Rice is an important source of energy and protein for the world population, mainly in Asia and Oceania. In Brazil, together with common beans, it is the population's basic food. Sustainable technologies that reduce rice production costs and increase productivity can warrant its supply on period of high demand. The objective of this study was to evaluate different preceding cover crops (millet [Pennisetum americanum

  3. Coberturas vegetais, doses de nitrogênio e inoculação de sementes com Azospirillum brasilense em arroz de terras altas no sistema plantio direto Cover crops, nitrogen rates and seeds inoculation with Azospirillum brasilense in upland rice under no-tillage

    Directory of Open Access Journals (Sweden)

    Douglas de Castilho Gitti

    2012-01-01

    Full Text Available O arroz é importante fonte de energia e proteínas para a população mundial, principalmente na Ásia e Oceania. No Brasil, juntamente com o feijão, constitui a base da alimentação. Tecnologias sustentáveis que reduzam custos da produção e aumentem a produtividade do arroz podem garantir seu suprimento em períodos de alta demanda. O objetivo deste trabalho foi avaliar diferentes coberturas vegetais antecessoras (milheto [Pennisetum americanum], crotalária [Crotalaria juncea], guandu [Cajanus cajan], braquiária [Brachiaria ruziziensis], milheto + crotalária e milheto + guandu, doses de nitrogênio (N em cobertura (0, 40, 80 e 120 kg ha-1 e o efeito da inoculação de sementes com Azospirillum brasilense no arroz de terras altas em sistema plantio direto no desenvolvimento e na produtividade. Utilizou-se o delineamento experimental em blocos casualizados em esquema fatorial 6x4x2 com quatro repetições. O estudo foi desenvolvido em um Latossolo Vermelho, em Selvíria, Estado do Mato Grosso do Sul, Brasil, em 2011/2012. O cultivo do guandu antecedendo o arroz proporcionou maior produtividade do arroz somente em comparação a B. ruziziensi. A produtividade do arroz em função das doses de N em cobertura se ajustou a uma função quadrática. Não houve influência da inoculação de sementes com A. brasilense sobre a produtividade do arroz, porém houve interação entre a inoculação e as coberturas vegetais sobre o teor de N foliar, número de panículas por m², matéria seca de plantas de arroz e a massa de cem grãos.Rice is an important source of energy and protein for the world population, mainly in Asia and Oceania. In Brazil, together with common beans, it is the population's basic food. Sustainable technologies that reduce rice production costs and increase productivity can warrant its supply on period of high demand. The objective of this study was to evaluate different preceding cover crops (millet [Pennisetum americanum

  4. Growth of Quailbush in Acidic, Metalliferous Desert Mine Tailings: Effect of Azospirillum brasilense Sp6 on Biomass Production and Rhizosphere Community Structure

    Science.gov (United States)

    de-Bashan, Luz E.; Hernandez, Juan-Pablo; Nelson, Karis N.; Bashan, Yoav

    2010-01-01

    Mine tailing deposits in semiarid and arid environments frequently remain devoid of vegetation due to the toxicity of the substrate and the absence of a diverse soil microbial community capable of supporting seed germination and plant growth. The contribution of the plant growth promoting bacterium (PGPB) Azospirillum brasilense Sp6 to the growth of quailbush in compost-amended, moderately acidic, high-metal content mine tailings using an irrigation-based reclamation strategy was examined along with its influence on the rhizosphere bacterial community. Sp6 inoculation resulted in a significant (2.2-fold) increase in plant biomass production. The data suggest that the inoculum successfully colonized the root surface and persisted throughout the 60-day experiment in both the rhizosphere, as demonstrated by excision and sequencing of the appropriate denaturing gradient gel electrophoresis (DGGE) band, and the rhizoplane, as indicated by fluorescent in situ hybridization of root surfaces. Changes in rhizosphere community structure in response to Sp6 inoculation were evaluated after 15, 30, and 60 days using DGGE analysis of 16S rRNA polymerase chain reaction amplicons. A comparison of DGGE profiles using canonical correspondence analysis revealed a significant treatment effect (Sp6-inoculated vs. uninoculated plants vs. unplanted) on bacterial community structure at 15, 30, and 60 days (p<0.05). These data indicate that in an extremely stressed environment such as acid mine tailings, an inoculated plant growth promoting bacterium not only can persist and stimulate plant growth but also can directly or indirectly influence rhizobacterial community development. PMID:20632001

  5. Extracellular polysaccharides are involved in the attachment of Azospirillum brasilense and Rhizobium leguminosarum to arbuscular mycorrhizal structures

    Directory of Open Access Journals (Sweden)

    V Bianciotto

    2009-12-01

    Full Text Available Arbuscular mycorrhizal (AM fungi, one of the most important component of the soil microbial community, establish physical interactions with naturally occurring and genetically modified bacterial biofertilizers and biopesticides, commonly referred to as plant growth-promoting rhizobacteria (PGPR. We have used a genetic approach to investigate the bacterial components possibly involved in the attachment of two PGPR (Azospirillum and Rhizobium to AM roots and AM fungal structures. Mutants affected in extracellular polysaccharides (EPS have been tested in in vitro adhesion assays and shown to be strongly impaired in the attachment to both types of surfaces as well as to quartz fibers. Anchoring of rhizobacteria to AM fungal structures may have special ecological and biotechnological significance because it may facilitate colonisation of new rhizospheres by the bacteria, and may be an essential trait for the development of mixed inocula.

  6. [Insertional mutation in the AZOBR_p60120 gene is accompanied by defects in the synthesis of lipopolysaccharide and calcofluor-binding polysaccharides in the bacterium Azospirillum brasilense Sp245].

    Science.gov (United States)

    Katsy, E I; Prilipov, A G

    2015-03-01

    In the bacterium Azospirillum brasilense Sp245, extracellular calcofluor-binding polysaccharides (Cal+ phenotype) and two types of lipopolysaccharides, LPSI and LPSII, were previously identified. These lipopolysaccharides share the same repeating O-polysaccharide unit but have different antigenic structures and different charges of their O-polysaccharides and/or core oligosaccharides. Several dozens of predicted genes involved in the biosynthesis of polysaccharides have been localized in the AZOBR_p6 plasmid of strain Sp245 (GenBank accession no. HE577333). In the present work, it was demonstrated that an artificial transposon Omegon-Km had inserted into the central region of the AZOBR_p60120 gene in the A. brasilense Sp245 LPSI- Cal- KM252 mutant. In A. brasilense strain Sp245, this plasmid gene encodes a putative glycosyltransferase containing conserved domains characteristic of the enzymes participating in the synthesis of O-polysaccharides and capsular polysaccharides (accession no. YP004987664). In mutant KM252, a respective predicted protein is expected to be completely inactivated. As a result of the analysis of the EcoRI fragment of the AZOBR_p6 plasmid, encompassing the AZOBR_p60120 gene and a number of other loci, novel data on the structure of AZOBR_p6 were obtained: an approximately 5-kb gap (GenBank accession no. KM189439) was closed in the nucleotide sequence of this plasmid.

  7. Elemental composition of strawberry plants inoculated with the plant growth-promoting bacterium Azospirillum brasilense REC3, assessed with scanning electron microscopy and energy dispersive X-ray analysis.

    Science.gov (United States)

    Guerrero-Molina, M F; Lovaisa, N C; Salazar, S M; Díaz-Ricci, J C; Pedraza, R O

    2014-07-01

    The elemental composition of strawberry plants (Fragaria ananassa cv. Macarena) inoculated with the plant growth-promoting bacterium Azospirillum brasilense REC3, and non-inoculated controls, was studied using scanning electron microscopy (SEM) and energy dispersive X-ray (EDS) analysis. This allowed simultaneous semi-quantification of different elements in a small, solid sample. Plants were inoculated and grown hydroponically in 50% or 100% Hoagland solution, corresponding to limited or optimum nutrient medium, respectively. Bacteria-inoculated plants increased the growth index 45% and 80% compared to controls when grown in 100% and 50% Hoagland solution, respectively. Thus, inoculation with A. brasilense REC3 in a nutrient-limited medium had the strongest effect in terms of increasing both shoot and root biomass and growth index, as already described for Azospirillum inoculated into nutrient-poor soils. SEM-EDS spectra and maps showed the elemental composition and relative distribution of nutrients in strawberry tissues. Leaves contained C, O, N, Na, P, K, Ca and Cu, while roots also had Si and Cl. The organic fraction (C, O and N) accounted for over 96.3% of the total chemical composition; of the mineral fraction, Na had higher accumulation in both leaves and roots. Azospirillum-inoculated and control plants had similar elemental quantities; however, in bacteria-inoculated roots, P was significantly increased (34.33%), which constitutes a major benefit for plant nutrition, while Cu content decreased (35.16%). © 2013 German Botanical Society and The Royal Botanical Society of the Netherlands.

  8. Metabolic profiling of two maize (Zea mays L.) inbred lines inoculated with the nitrogen fixing plant-interacting bacteria Herbaspirillum seropedicae and Azospirillum brasilense

    Science.gov (United States)

    Brusamarello-Santos, Liziane Cristina; Gilard, Françoise; Brulé, Lenaïg; Quilleré, Isabelle; Gourion, Benjamin; Ratet, Pascal; Maltempi de Souza, Emanuel; Lea, Peter J.; Hirel, Bertrand

    2017-01-01

    Maize roots can be colonized by free-living atmospheric nitrogen (N2)-fixing bacteria (diazotrophs). However, the agronomic potential of non-symbiotic N2-fixation in such an economically important species as maize, has still not been fully exploited. A preliminary approach to improve our understanding of the mechanisms controlling the establishment of such N2-fixing associations has been developed, using two maize inbred lines exhibiting different physiological characteristics. The bacterial-plant interaction has been characterized by means of a metabolomic approach. Two established model strains of Nif+ diazotrophic bacteria, Herbaspirillum seropedicae and Azospirillum brasilense and their Nif- couterparts defficient in nitrogenase activity, were used to evaluate the impact of the bacterial inoculation and of N2 fixation on the root and leaf metabolic profiles. The two N2-fixing bacteria have been used to inoculate two genetically distant maize lines (FV252 and FV2), already characterized for their contrasting physiological properties. Using a well-controlled gnotobiotic experimental system that allows inoculation of maize plants with the two diazotrophs in a N-free medium, we demonstrated that both maize lines were efficiently colonized by the two bacterial species. We also showed that in the early stages of plant development, both bacterial strains were able to reduce acetylene, suggesting that they contain functional nitrogenase activity and are able to efficiently fix atmospheric N2 (Fix+). The metabolomic approach allowed the identification of metabolites in the two maize lines that were representative of the N2 fixing plant-bacterial interaction, these included mannitol and to a lesser extend trehalose and isocitrate. Whilst other metabolites such as asparagine, although only exhibiting a small increase in maize roots following bacterial infection, were specific for the two Fix+ bacterial strains, in comparison to their Fix- counterparts. Moreover, a number

  9. Metabolic profiling of two maize (Zea mays L. inbred lines inoculated with the nitrogen fixing plant-interacting bacteria Herbaspirillum seropedicae and Azospirillum brasilense.

    Directory of Open Access Journals (Sweden)

    Liziane Cristina Brusamarello-Santos

    Full Text Available Maize roots can be colonized by free-living atmospheric nitrogen (N2-fixing bacteria (diazotrophs. However, the agronomic potential of non-symbiotic N2-fixation in such an economically important species as maize, has still not been fully exploited. A preliminary approach to improve our understanding of the mechanisms controlling the establishment of such N2-fixing associations has been developed, using two maize inbred lines exhibiting different physiological characteristics. The bacterial-plant interaction has been characterized by means of a metabolomic approach. Two established model strains of Nif+ diazotrophic bacteria, Herbaspirillum seropedicae and Azospirillum brasilense and their Nif- couterparts defficient in nitrogenase activity, were used to evaluate the impact of the bacterial inoculation and of N2 fixation on the root and leaf metabolic profiles. The two N2-fixing bacteria have been used to inoculate two genetically distant maize lines (FV252 and FV2, already characterized for their contrasting physiological properties. Using a well-controlled gnotobiotic experimental system that allows inoculation of maize plants with the two diazotrophs in a N-free medium, we demonstrated that both maize lines were efficiently colonized by the two bacterial species. We also showed that in the early stages of plant development, both bacterial strains were able to reduce acetylene, suggesting that they contain functional nitrogenase activity and are able to efficiently fix atmospheric N2 (Fix+. The metabolomic approach allowed the identification of metabolites in the two maize lines that were representative of the N2 fixing plant-bacterial interaction, these included mannitol and to a lesser extend trehalose and isocitrate. Whilst other metabolites such as asparagine, although only exhibiting a small increase in maize roots following bacterial infection, were specific for the two Fix+ bacterial strains, in comparison to their Fix- counterparts

  10. Metabolic profiling of two maize (Zea mays L.) inbred lines inoculated with the nitrogen fixing plant-interacting bacteria Herbaspirillum seropedicae and Azospirillum brasilense.

    Science.gov (United States)

    Brusamarello-Santos, Liziane Cristina; Gilard, Françoise; Brulé, Lenaïg; Quilleré, Isabelle; Gourion, Benjamin; Ratet, Pascal; Maltempi de Souza, Emanuel; Lea, Peter J; Hirel, Bertrand

    2017-01-01

    Maize roots can be colonized by free-living atmospheric nitrogen (N2)-fixing bacteria (diazotrophs). However, the agronomic potential of non-symbiotic N2-fixation in such an economically important species as maize, has still not been fully exploited. A preliminary approach to improve our understanding of the mechanisms controlling the establishment of such N2-fixing associations has been developed, using two maize inbred lines exhibiting different physiological characteristics. The bacterial-plant interaction has been characterized by means of a metabolomic approach. Two established model strains of Nif+ diazotrophic bacteria, Herbaspirillum seropedicae and Azospirillum brasilense and their Nif- couterparts defficient in nitrogenase activity, were used to evaluate the impact of the bacterial inoculation and of N2 fixation on the root and leaf metabolic profiles. The two N2-fixing bacteria have been used to inoculate two genetically distant maize lines (FV252 and FV2), already characterized for their contrasting physiological properties. Using a well-controlled gnotobiotic experimental system that allows inoculation of maize plants with the two diazotrophs in a N-free medium, we demonstrated that both maize lines were efficiently colonized by the two bacterial species. We also showed that in the early stages of plant development, both bacterial strains were able to reduce acetylene, suggesting that they contain functional nitrogenase activity and are able to efficiently fix atmospheric N2 (Fix+). The metabolomic approach allowed the identification of metabolites in the two maize lines that were representative of the N2 fixing plant-bacterial interaction, these included mannitol and to a lesser extend trehalose and isocitrate. Whilst other metabolites such as asparagine, although only exhibiting a small increase in maize roots following bacterial infection, were specific for the two Fix+ bacterial strains, in comparison to their Fix- counterparts. Moreover, a number

  11. Plasmid AZOBR_p1-borne fabG gene for putative 3-oxoacyl-[acyl-carrier protein] reductase is essential for proper assembly and work of the dual flagellar system in the alphaproteobacterium Azospirillum brasilense Sp245.

    Science.gov (United States)

    Filip'echeva, Yulia A; Shelud'ko, Andrei V; Prilipov, Alexei G; Burygin, Gennady L; Telesheva, Elizaveta M; Yevstigneyeva, Stella S; Chernyshova, Marina P; Petrova, Lilia P; Katsy, Elena I

    2018-02-01

    Azospirillum brasilense can swim and swarm owing to the activity of a constitutive polar flagellum (Fla) and inducible lateral flagella (Laf), respectively. Experimental data on the regulation of the Fla and Laf assembly in azospirilla are scarce. Here, the coding sequence (CDS) AZOBR_p1160043 (fabG1) for a putative 3-oxoacyl-[acyl-carrier protein (ACP)] reductase was found essential for the construction of both types of flagella. In an immotile leaky Fla - Laf - fabG1::Omegon-Km mutant, Sp245.1610, defects in flagellation and motility were fully complemented by expressing the CDS AZOBR_p1160043 from plasmid pRK415. When pRK415 with the cloned CDS AZOBR_p1160045 (fliC) for a putative 65.2 kDa Sp245 Fla flagellin was transferred into the Sp245.1610 cells, the bacteria also became able to assemble a motile single flagellum. Some cells, however, had unusual swimming behavior, probably because of the side location of the organelle. Although the assembly of Laf was not restored in Sp245.1610 (pRK415-p1160045), this strain was somewhat capable of swarming motility. We propose that the putative 3-oxoacyl-[ACP] reductase encoded by the CDS AZOBR_p1160043 plays a role in correct flagellar location in the cell envelope and (or) in flagellar modification(s), which are also required for the inducible construction of Laf and for proper swimming and swarming motility of A. brasilense Sp245.

  12. Características agronômicas do trigo em função de Azospirillum brasilense, ácidos húmicos e nitrogênio em casa de vegetação

    Directory of Open Access Journals (Sweden)

    Luan F. O. S. Rodrigues

    2014-01-01

    Full Text Available Objetivou-se, neste estudo, verificar o efeito do uso combinado de Azospirillum brasilense, ácidos húmicos e diferentes doses de nitrogênio nas características agronômicas do trigo. Os experimentos foram instalados no dia 21 de maio de 2011 e a colheita foi procedida no dia 13 de setembro de 2011. O delineamento experimental adotado foi o de blocos casualizados em esquema fatorial 4 x 4, com quatro repetições. O primeiro fator se refere à combinação da estirpe Ab-V5 de A. brasilense com os ácidos húmicos, sendo utilizados os seguintes tratamentos: controle; Ab-V5; ácido húmico e Ab-V5+ácido húmico e o segundo fator se refere às doses de nitrogênio (0, 30, 60 e 90 kg ha-1 N. A maioria das variáveis em análise apresentou efeito linear positivo dos tratamentos em função da adubação nitrogenada sendo que apenas para a variável massa de cem grãos este efeito foi linear negativo. Não houve diferença significativa entre as variâncias, na produção de grãos. Pôde-se concluir que o uso combinado de Ab-V5 + ácido húmico promove principalmente a produção de matéria seca de folhas e não é responsivo à adubação nitrogenada para os demais componentes produtivos em estudo nem para a produtividade dos grãos.

  13. Aspectos morfofisiológicos de plantas de milho e bioquímico do solo em resposta à adubação nitrogenada e à inoculação com Azospirillum brasilense

    Directory of Open Access Journals (Sweden)

    Tâmara Prado de Morais

    2015-12-01

    Full Text Available RESUMO O nitrogênio (N é um macronutriente que aumenta a produção de grãos na cultura do milho e o seu manejo adequado torna-se indispensável como proposta de uma agricultura sustentável, incluindo o uso de fontes alternativas como bactérias fixadoras de N2. Os objetivos deste trabalho foram avaliar a resposta morfofisiológica de plantas de milho e a atividade de enzimas no solo (urease e fosfatase decorrente da adubação N mineral e da inoculação com Azospirillum brasilense. Dois ensaios foram realizados em condições de casa de vegetação com solo de cerrado. O delineamento estatístico adotado foi o de blocos ao acaso com os tratamentos distribuídos em esquema fatorial 3 x 3, sendo o primeiro fator correspondente a doses de N (0; 100 e 200 kg ha-1 e o segundo, a doses de um inoculante líquido à base de A. brasilense aplicado via sementes (0; 100 e 200 mL ha-1. Ao final desse experimento, outro ensaio foi realizado para verificar o possível efeito residual da inoculação e da adubação nitrogenada. A adição de fertilizantes nitrogenados promoveu maior desenvolvimento das plantas de milho, elevou os teores de clorofila e de nutrientes. Houve aumento da atividade das enzimas relacionadas à disponibilização de amônio e fósforo inorgânico na rizosfera. Além disso, o nitrogênio apresentou efeito residual no desenvolvimento das plantas na semeadura subsequente. A dose de 200 mL ha-1 de A. brasilense associada à dose de 200 kg ha-1 de N aumentou a resposta fisiológica da cultura.

  14. Effect of Azospirillum brasilense on the harvest and radical development of sugar cane plants, variety C86 - 456, obtained by in vitro culture in normal conditions and under overhumidity of soil

    Directory of Open Access Journals (Sweden)

    Sergio Rodríguez Rodríguez

    2005-01-01

    Full Text Available In order to know the influence of the bacteria Azospirillum brasilense on plants of sugar cane, cultivar C86-456, from tissue culture under normal conditions and flooded soil in a Vertisol from El Valle del Cauto, an experiment was carried out using an at random blocks design. The main crop variables (pol in cane, t. caña.ha-1 and t. pol.ha-1 at the twelve months of age were taken, as stump of spring of the year and the development reached by the radical system in its more active area to achieve this experiment. The best results in the crop variables and development of the radical system were obtained it the treatments where the bacteria was present, although non significant under both conditions, evidencing that the stress due to excess of water in the soil affects the normal development of the sugar cane in general by modifying the kindness that the rhizospheric microorganism provides. Key words: biofertilizer, radical system, Saccharum, yield

  15. Identification and Isolation of Genes Involved in Poly(β-Hydroxybutyrate) Biosynthesis in Azospirillum brasilense and Characterization of a phbC Mutant

    OpenAIRE

    Kadouri, Daniel; Burdman, Saul; Jurkevitch, Edouard; Okon, Yaacov

    2002-01-01

    Like many other prokaryotes, rhizobacteria of the genus Azospirillum produce high levels of poly(β-hydroxybutyrate) (PHB) under suboptimal growth conditions. Utilization of PHB by bacteria under stress has been proposed as a mechanism that favors their compatible establishment in competitive environments, thus showing great potential for the improvement of bacterial inoculants for plants and soils. The three genes that are considered to be essential in the PHB biosynthetic pathway, phbA (β-ke...

  16. Assessment of N2 fixing efficiency of Beijerinckia indica and Azospirillum brasilense in Sorghum (Sorghum bicolor (L.) moench) using 15N tracer

    International Nuclear Information System (INIS)

    Kanimoli, S.; Marimuthu, P.; Arulmozhiselvan, K.

    2010-01-01

    For studying the benefits of inoculation of N 2 fixing diazotrophs in the root zone of sorghum crop, a pot culture was conducted on neutral red sandy loam soil with sorghum cv. CO26, using 15 N tracer. At the end of 45 days duration after sowing, Beijerinckia indica inoculation contributed 56.9 per cent N derived from N 2 fixation, out of total N concentration in whole drymatter of sorghum plant. It proved to be the efficient N 2 fixer by contributing N from N 2 fixation to the tune of 17.6 Kg -1 . Accumulation of N derived from N 2 fixation from B. indica was primarily in leaf blade (50.0%) followed by stem (31.8%), leaf sheath (14.0%) and root (4.2%). Inoculation of Azospirillum brasllense accelerated uptake of N from soil and fertilizer N sources compared to B. indica and hence registered low N fixation. (author)

  17. INTERAÇÃO ENTRE BACTÉRIAS Azospirillum brasilense E Herbaspirillum seropedicae COM ADUBAÇÃO NITROGENADA, VISANDO O FORNECIMENTO DE NITROGÊNIO PARA O MILHO

    Directory of Open Access Journals (Sweden)

    Luiz Claudio Offemann

    2015-12-01

    Full Text Available This study aimed to investigate the interaction between the bacteria A. brasilense and H. seropedicae associated with nitrogen fertilization, aiming to supply nitrogen for corn crop. The experimental design was randomized blocks, in 4 x 3 factorial design with four replications. The first factor was formed by the treatments: no inoculation, inoculation H. seropedicae and A. brasilense in isolation and combination of the two strains. The second factor referred to nitrogen levels, 0, 60 and 120 kg ha-1 of N. Each experimental plot consisted of six corn lines of 3.5 meters, where the evaluation of yield components was performed: number of rows grain and number of kernels per row, thousand grain mass, average mass of grains per spike and productivity. Isolated inoculation with the bacteria A. brasilense (AbV5 and H. seropedicae (SMR1 resulted in gains especially for thousand grain weight, which can be observed that for less than the maximum dose of nitrogen doses, remained the same yield. There were no gains in productivity with respect to the use of corn seed inoculation with rhizobacteria of the genus A. brasilense (AbV5 and H. seropedicae (SMR1 in relation to nitrogen fertilization.

  18. ProClaT, a new bioinformatics tool for in silico protein reclassification: case study of DraB, a protein coded from the draTGB operon in Azospirillum brasilense.

    Science.gov (United States)

    Rubel, Elisa Terumi; Raittz, Roberto Tadeu; Coimbra, Nilson Antonio da Rocha; Gehlen, Michelly Alves Coutinho; Pedrosa, Fábio de Oliveira

    2016-12-15

    Azopirillum brasilense is a plant-growth promoting nitrogen-fixing bacteria that is used as bio-fertilizer in agriculture. Since nitrogen fixation has a high-energy demand, the reduction of N 2 to NH 4 + by nitrogenase occurs only under limiting conditions of NH 4 + and O 2 . Moreover, the synthesis and activity of nitrogenase is highly regulated to prevent energy waste. In A. brasilense nitrogenase activity is regulated by the products of draG and draT. The product of the draB gene, located downstream in the draTGB operon, may be involved in the regulation of nitrogenase activity by an, as yet, unknown mechanism. A deep in silico analysis of the product of draB was undertaken aiming at suggesting its possible function and involvement with DraT and DraG in the regulation of nitrogenase activity in A. brasilense. In this work, we present a new artificial intelligence strategy for protein classification, named ProClaT. The features used by the pattern recognition model were derived from the primary structure of the DraB homologous proteins, calculated by a ProClaT internal algorithm. ProClaT was applied to this case study and the results revealed that the A. brasilense draB gene codes for a protein highly similar to the nitrogenase associated NifO protein of Azotobacter vinelandii. This tool allowed the reclassification of DraB/NifO homologous proteins, hypothetical, conserved hypothetical and those annotated as putative arsenate reductase, ArsC, as NifO-like. An analysis of co-occurrence of draB, draT, draG and of other nif genes was performed, suggesting the involvement of draB (nifO) in nitrogen fixation, however, without the definition of a specific function.

  19. Partial characterization of nif genes from the bacterium Azospirillum amazonense

    Directory of Open Access Journals (Sweden)

    D.P. Potrich

    2001-09-01

    Full Text Available Azospirillum amazonense revealed genomic organization patterns of the nitrogen fixation genes similar to those of the distantly related species A. brasilense. Our work suggests that A. brasilense nifHDK, nifENX, fixABC operons and nifA and glnB genes may be structurally homologous to the counterpart genes of A. amazonense. This is the first analysis revealing homology between A. brasilense nif genes and the A. amazonense genome. Sequence analysis of PCR amplification products revealed similarities between the amino acid sequences of the highly conserved nifD and glnB genes of A. amazonense and related genes of A. brasilense and other bacteria. However, the A. amazonense non-coding regions (the upstream activator sequence region and the region between the nifH and nifD genes differed from related regions of A. brasilense even in nitrogenase structural genes which are highly conserved among diazotrophic bacteria. The feasibility of the 16S ribosomal RNA gene-based PCR system for specific detection of A. amazonense was shown. Our results indicate that the PCR primers for 16S rDNA defined in this article are highly specific to A. amazonense and can distinguish this species from A. brasilense.

  20. Cellulose decomposition and associated nitrogen fixation by mixed cultures of Cellulomonas gelida and Azospirillum species or Bacillus macerans

    Energy Technology Data Exchange (ETDEWEB)

    Halsall, D.M.; Gibson, A.H.

    1985-10-01

    Mixed cultures of Cellulomonas gelida plus Azospirillum lipoferum or Azospirillum brasilense and C. gelida plus Bacillus macerans were shown to degrade cellulose and straw and to utilize the energy-yielding products to fix atmospheric nitrogen. This cooperative process was followed over 30 days in sand-based cultures in which the breakdown of 20% of the cellulose and 28 to 30% of the straw resulted in the fixation of 12 to 14.6 mg of N per g of cellulose and 17 to 19 mg of N per g of straw consumed. Cellulomonas species have certain advantages over aerobic cellulose-degrading fungi in being able to degrade cellulose at oxygen concentrations as low as 1% O/sub 2/ (vol/vol) which would allow a close association between cellulose-degrading and microaerobic diazotrophic microorganisms. Cultures inoculated with initially different proportions of A. brasilense and C. gelida all reached a stable ratio of approximately 1 Azospirillum/3 Cellulomonas cells.

  1. [Identification of Azospirillum genus bacteria isolated from the spring wheat root zone].

    Science.gov (United States)

    Kopylov, Ie P; Spyrydonov, V H; Patyka, V P

    2009-01-01

    Bacteria with high N2-fixing activity were isolated from the root zone of spring wheat grown on leach chernozem and soddy podzolic soil in Ukrainian marshy woodlands. They were characterized by phenotypic signs and investigated with the help of molecular-genetic methods. On the basis of diagnostic signs the investigated strains were referred to Azospirillum brasilense from Azospirillum genus. Their 3'- and 5'-thermal 16S RNA hypervariable sites with length from 373 to 395 nucleotides were amplified and sequenced. The comparative analysis of results confirmed the 100% identity of 16S RNA sequences from investigated bacteria with the same sequences of A. brasilense from Gene Bank database. Thus the results of sequence analysis agree with results obtained during the investigation of phenotypic signs.

  2. STUDY OF AZOSPIRILLUM LECTINS INFLUENCE ON HYDROGEN PEROXIDE PRODUCTION IN WHEAT-ROOTS

    Directory of Open Access Journals (Sweden)

    Alen’kina S.A.

    2009-12-01

    Full Text Available It was found that two cell-surface lectins isolated from the nitrogen-fixing soil bacterium Azospirillum brasilense Sp7 and from its mutant defective in lectin activity, A. brasilense Sp7.2.3 can stimulate rapid formation of hydrogen peroxide, associated with an increase in the activities of oxalate oxidase and peroxidase in the roots of wheat seedlings. The most advantageous and most rapidly induced pathway of hydrogen peroxide formation was the oxidation of oxalic acid by oxalate oxidase because in this case, a 10-min treatment of the roots with the lectins at 10 µg ml-1 was sufficient. The data from this study attest that the Azospirillum lectins can act as inducers of adaptation processes in the roots of wheat seedlings.

  3. [Effect of Azospirillum lectins on the Activity of Proteolytic Enzymes and Their Inhibitors in Wheat Seedling Roots].

    Science.gov (United States)

    Alen'kina, S A; Nikitina, V E

    2015-01-01

    The lectins of associative nitrogen-fixing strains Azospirillum brasilense Sp7 and Sp245 were shown to exerte a multidirectional effect on the activity of acidic (pH 3.5), neutral (6.8), and alkaline (pH 7.8) proteinases. The lectin of the epiphytic A. brasilense Sp7 decreased proteolytic activity at all pH values, whereas the lectin of the endophytic A. brasilense Sp245 activated neutral and alkaline proteinases, while not affecting the alkaline ones. Experiments with protease inhibitors made it possible to conclude that the lectins of the studied A. brasilense strains alter the ratio between the activities of different protease types in germinating seeds. The activity of trypsin inhibitors in wheat seedling roots was found to increase in the presence of the lectins. Our results indicate a broader spectrum of effects of azospirilla lectins on the host plant organism.

  4. Azospirillum Inoculation Alters Nitrate Reductase Activity and Nitrogen Uptake in Wheat Plant Under Water Deficit Conditions

    OpenAIRE

    N. Aliasgharzad, N. Aliasgharzad; Heydaryan, Zahra; Sarikhani, M.R

    2014-01-01

    Water deficit stress usually diminishes nitrogen uptake by plants. There are evidences that some nitrogen fixing bacteria can alleviate this stress by supplying nitrogen and improving its metabolism in plants. Four Azospirillum strains, A. lipoferum AC45-II, A. brasilense AC46-I, A. irakense AC49-VII and A. irakense AC51-VI were tested for nitrate reductase activity (NRA). In a pot culture experiment using a sandy loam soil, wheat plants (Triticum aestivum L. cv. Sardari) were inoculated with...

  5. Polymers selection for a liquid inoculant of Azospirillum brasilense ...

    African Journals Online (AJOL)

    Sandra Lucia Cortes Patiño

    2015-08-19

    Aug 19, 2015 ... Arrhenius thermodynamic model, we calculated the time required to reduce cell concentration in ... over cell viability, and with first-order kinetics, determine ..... Phenomenological approach to deviations from Arrhenius law.

  6. Efecto de la coinmovilización de la microalga Chlorella sorokiniana con la bacteria promotora de crecimiento vegetal Azospirillum brasilense, en el crecimiento poblacional microalgal y capacidad de remoción de amonio como uso potencial en el tratamiento..

    Directory of Open Access Journals (Sweden)

    Lina María González González

    2006-01-01

    de C. sorokiniana con A. brasilense, muestra la habilidad de esta bacteria para influir de manera positiva en el crecimiento y fisiología de la microalga y por lo tanto la remoción de amonio puede ser incrementada.

  7. Polyhydroxyalcanoates of strains of Azospirillum spp. isolated of roots of Lycopersicon esculentum Mill. “tomato” and Oryza sativa L. “rice” in Lambayeque

    Directory of Open Access Journals (Sweden)

    Katty Baca

    2010-12-01

    Full Text Available In this work was determined the concentration of polyhydroxyalkanoates (PHAs of Azospirillum strains isolated from roots of Lycopersicon esculentum Mill "tomato" and Oryza sativa L. "rice" as an alternative to accumulation of petroleum-based plastics. Previously disinfected root were plated in Nfb semisolid medium where nitrogen-fixing bacteria were recognized by a whitish film on the surface and turn from green to blue. The genus Azospirillum was identified in Congo red agar medium, obtained 96 isolates of A. lipoferum and A. brasilense on tomato and rice. Batch fermentation was performed with broth Azotobacter modified feeding a saturated solution of malic acid every 12 hours and were stained with Sudan Black B. Strains were selected with the greatest number of PHAs granules (in tomato, 18 of A. lipoferum and 2 of A. brasilense; in rice, 10 of A. lipoferum and 10 of A. brasilense and quantified the biomass and PHAs. PHAs concentration reached 0.661 gL-1 in A. lipoferum KM(T-73 and 0.738 gL-1 in A. brasilense KM(T-19, both isolated from tomato. Strains of A. lipoferum and A. brasilense isolated from tomato reached a higher concentration of biomass and PHAs against the strains of rice.

  8. Plant Cell Protolytic Enzymes Activity under Exposure to Lectins of Endophytic and Epiphytic Azospirillum Strains

    Directory of Open Access Journals (Sweden)

    S.A. Alen’kina

    2016-05-01

    Full Text Available We studied the ability of lectins isolated from the surface of the two strains of nitrogen-fixing soil bacteria of the genus Azospirillum, A. brasilense Sp7 (epiphytic and A. brasilense Sp245 (endophytic, to show have a regulating effect on the activity of pectinolytic enzymes in the roots of wheat seedlings. Research results showed that the lectins under study can cause the induction of the activity of polygalacturonase, pectinesterase, pectatlyase from the plant cell wall, thereby ensuring the bacteria penetration in the plant tissues, as well as the induction of plants responses which, being combined with growth-stimulating effect of bacteria, contributes to the formation of plants stability and productivity.

  9. Characterization and effect of Azotobacter, Azospirillum and Pseudomonas associated with Ipomoea Batatas of Colombian Caribbean

    Directory of Open Access Journals (Sweden)

    Jazmín Vanessa Pérez-Pazos

    2017-07-01

    Full Text Available The use of plant growth promoting Rhizobacteria (PGPR is an alternative to replace chemical fertilizers for the cultivation of agricultural crops. The aim of this research was to search, selection and characterization of PGPR from the genus Azotobacter, Azospirillum and Pseudomonas natives from sweet potato (Ipomoea batatas plants and rhizosphere of representative production regions of the Colombian Caribbean. Selected isolates were identified by molecular methods and they were screened in vitro for activities related to plant growth such as phosphate solubilization, indole production and acetylene reduction. The strains were tested in the greenhouse on plants of Ipomoea batatas produced in vitro. The height, root length, dry mass of the shot and root were evaluated. Associated with sweet potato crop us finded strains identificated as Azotobacter vinelandii, Azotobacter chroococcum, Azospirillum lipoferum, Azospirillum brasilense and Pseudomonas denitrificans. The strains were able to solubilize phosphate, synthesize indole-3-acetic acid (IAA and reduce acetylene. The inoculation of bacteria selected increased growth parameters such as root length, height, dry weight root and shoot in plants of sweet potato in greenhouse. Those results catalog to the isolated obtained as possible microorganisms with potential as biofertilizers in sweet potato.

  10. Increased Growth of the Microalga Chlorella vulgaris when Coimmobilized and Cocultured in Alginate Beads with the Plant-Growth-Promoting Bacterium Azospirillum brasilense†

    Science.gov (United States)

    Gonzalez, Luz E.; Bashan, Yoav

    2000-01-01

    Coimmobilization of the freshwater microalga Chlorella vulgaris and the plant-growth-promoting bacterium Azospirillum brasilense in small alginate beads resulted in a significantly increased growth of the microalga. Dry and fresh weight, total number of cells, size of the microalgal clusters (colonies) within the bead, number of microalgal cells per cluster, and the levels of microalgal pigments significantly increased. Light microscopy revealed that both microorganisms colonized the same cavities inside the beads, though the microalgae tended to concentrate in the more aerated periphery while the bacteria colonized the entire bead. The effect of indole-3-acetic acid addition to microalgal culture prior to immobilization of microorganisms in alginate beads partially imitated the effect of A. brasilense. We propose that coimmobilization of microalgae and plant-growth-promoting bacteria is an effective means of increasing microalgal populations within confined environments. PMID:10742237

  11. Change in the Content of Salicylic Acid and in the Activities of Phenylalanine Ammonia-Lyase and Catalase in Wheat Seedling Roots Under the Effect of Azospirillum Lectins

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    Alen'kina S.A.

    2012-05-01

    Full Text Available We investigated the time course of changes in the endogenous content of salicylic acid, the ratio between the acid's free and bound forms, and changes in the activities of phenylalanine ammonia-lyase and catalase in wheat seedling roots under the effect of the lectins of two strains of the associative nitrogen-fixing bacterium Azospirillum: A. brasilense Sp7 and its mutant defective in lectin activity, A. brasilense Sp7.2.3. Differences in plant response to the action of the lectins from these two strains were established. On the basis of the obtained data, a model was proposed for lectin-assisted induction of resistance, according to which the lectin effect on the roots of seedlings results in accumulation of free salicylic acid, which inhibits catalase activity, ultimately leading to accumulation of hydrogen peroxide and to formation of induced resistance.

  12. Polihidroxialcanoatos de cepas de Azospirillum spp. aisladas de raíces de Lycopersicon esculentum Mill. “tomate” y Oryza sativa L. “arroz” en Lambayeque

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    Katty Baca

    2010-01-01

    Full Text Available En este trabajo se determinó la concentración de polihidroxialcanoatos (PH As de cepas de Azospirillum aisladas de raíces de Lycopersicon esculentum Mill. “tomate” y Oryza sativa L. “arroz”, como una alternativa ante la acumulación de plásticos derivados del petróleo. R aíces previamente desinfectadas se sembraron en medio Nfb se misólido, donde las bacterias fijadoras de nitrógeno se reconocieron por una película blanquecina bajo la superficie y el viraje del indicador al azul. El género Azospirillum se identificó en medio rojo de Congo, obteniéndose 96 cepas de A. lipoferum y A. brasilense en tomate y arroz. Se realizó una fermentación discontinua con caldo Azotobacter modificado, alimentando con una solución saturada de ácido málico cada 12 horas y se realizaron tinciones con Sudán Negro B. Se seleccionaron las cepas con mayor nú mero de gránulos de PHAs (en tomate , 18 de A. lipoferum y 2 de A. brasilense y en arroz, 10 de A. lipoferum y 10 de A. brasilense y se cuantificó la biomasa y PHAs. La concentración de PHAs alcanzó 0 . 661 gL - 1 en A. lipoferum KM(T - 73 y 0 . 738 gL - 1 en A. br asilense KM(T - 19. Las cepas de A. lipoferum y A. brasilense aisladas de tomate alcanzaron una mayor concentración de biomasa y PHAs frente a las cepas aisladas de arroz.

  13. Improvement of Canola (Brassica napus L.) Inoculated with Rhizobium, Azospirillum and/or Mycorrhizal Fungi Under Salinity Stress

    International Nuclear Information System (INIS)

    El-Ghandour, I. A.; Galal, Y.G; Ebraheem, Rabab M.M.; Yousef, Khayria A.

    2004-01-01

    Bio fertilization technology was applied for improving canola plant growth and nutrient acquisition in sandy saline soil ,as a biological mean used to develop plant growth and nutrient uptake under salinity stress. Canola was cultivated in pots packed at rate of 7 kg saline sandy soil pot -1 , and inoculated with Rhizobium leguminosarum biovar viceae, Azospirillum brasilense strain no. 40 and arbuscular mycorrhizal fungi either solely or in combinations of them. Nitrogen fertilizer was added in form ( 15 NH 4 ) 2 SO 4 with 5% 15 N atom excess at rate of 0.99 g N pot -1 . Maximum dry matter accumulation induced by composite inoculation (Rh + Azo + AM). Na concentrations were frequently affected by Rhizobium and /or mycorrhizae while K was affected by Azospirillum and /or mycorrhizae. Azospirillum enhanced Ca uptake whereas Mg content was responded well to composite inoculants of Rh + Azo + AM. Dual inoculation with Rh + Azo resulted in the highest values of N uptake by plant. Similar effect was noticed with P uptake when dual inoculums of Azo + AM were applied. Data of 15 N isotope showed that the highest portion and value of N 2 -fixed was recorded with composite inoculums followed by dual inoculations. On the other hand, the infection with AM fungi gave the highest proportion of N derived from fertilizer as compared to other inoculants or uninoculated control. In the same trend, the fertilizer use efficiency (FUE%) was enhanced by AM infection. Dual inoculums of Rh + Azo induced highest content of proline in leaves. (Authors)

  14. Nitrogen fixation associated with development and localization of mixed populations of Cellulomonas species and Azospirillium brasilense grown on cellulose or wheat straw

    Energy Technology Data Exchange (ETDEWEB)

    Halsall, D.M.; Goodchild, D.J.

    1986-04-01

    Mixed cultures of Cellulomonas sp. and Azospirillum brasilense were grown with straw or cellulose as the carbon source under conditions favoring the fixation of atmospheric nitrogen. Rapid increases in cell numbers, up to 10/sup 9/ cells per g of substrate, were evident after 4 and 5 days of incubation at 30 degrees C for cellulose and straw, respectively. Nitrogen fixation (detected by acetylene reduction measured on parallel cultures) commenced after 2 and 4 days of incubation for straw and cellulose, respectively, and continued for the duration of the experiment. Pure cultures of Cellulomonas sp. showed an increase in cell numbers, but CO/sub 2/ production was low, and acetylene reduction was not detected on either cellulose or straw. Pure cultures of A. brasilense on cellulose showed an inital increase in cell numbers (10/sup 7/ cells per g of substrate) over 4 days, followed by a decline presumably caused by the exhaustion of available carbon substrate. On straw, A. brasilense increased to 10/sup 9/ cells per g of substrate over 5 days and then declined slowly; this growth was accompanied by acetylene reduction. Scanning electron micrographs of straw incubated with a mixture under the above conditions for 8 days showed cells of both species in close proximity to each other. Evidence was furnished that the close spatial relatioship of cells from the two species facilitated the mutally beneficial association between them and thus increased the efficiency with which the products of straw breakdown were used for nitrogen fixation. 17 references.

  15. Лигнин-пероксидаза фенолоксидазного комплекса ассоциативных бактерий Azospirillum brasilense

    OpenAIRE

    Петров, Сергей; Купряшина, Мария; Глинская, Елена; Никитина, Валентина

    2014-01-01

    Впервые установлена способность бактерий A. brasilense к росту на лигнинсодержащих субстратах, обнаружена лигнинолитическая активность, которая в большей степени выражена у эн-дофитного штамма. Впервые обнаружена способность бактерий A. brasilense к деградации лигнина. Впервые получен чистый препарат бактериальной внеклеточной лигнин-пероксидазы. Высказано предположение об участии данного фермента в лигниндеградирующей способности азоспирилл....

  16. Synthesis of poly(3-hydroxybutyrate using enzymes Azospirillum brasilense in vitro

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    Soheila Abbasi

    2017-06-01

    Full Text Available Introduction:Polyhydroxyalkaniates (PHAS are bacterial polymers that are formed as naturally occurring storage polyesters by a wide range of microorganisms usually under unbalanced growth conditions. Mechanical properties of PHAS make them suitable replacements for petrochemically produced bulk plastics (polyethylene, polypropylene etc., but in contrast to these commodity plastics PHA are completely degradable to carbon dioxide and water through natural microbiological mineralization. PHAS can be produced by biotechnological processes under controlled conditions. Polyhydroxybotyric acid (PHB was the first of thePHAS discovered and is the most abundant polyester found in bacteria. Materials and methods: First, a rich bacterial suspension prepared from poly(3-hydroxybutyrate, then the cells were broken down and ensure the absence of live cells.The cell free enzymes were added to M9 medium.Then the sample turbidity was measured at a wavelength of 600 nm and incubated at 30°C and centrifiuged at 120rpm. Next, the amount of PHB as well as solution turbidity were measured and compared with control. The physical and chemical analyzes of extracted PHB samples such as UV absorbtion, FTIR, HPLC and HNMR assesed and compared with standard sample. Results: In twelve days this experiment was conducted, from the third day, the amount of polyhydroxybutyrate was measurable and the highest polyhydroxybutyrate was gained on the tenth day. The level of PHB was constant. Moreover, the level of glucose was decreased gradually till the tenth day. By Physico-chemical analysis, production of polyhydroxybutyrate was approved. Discussion and conclusion: In this experiment, the reaction efficiency was 37.5 percent. Probably the rest of glucose could be changed to other intermediate compounds by other enzymes in the sample.Therefore, by purification of the enzyme, usage of specific substrate and optimization of conditions outside the cell could help the production of polyhydroxybutyrate continually. Production is very cost-effective, by this method.

  17. Combination of inoculation methods of Azospirilum brasilense with broadcasting of nitrogen fertilizer increases corn yield

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    Tânia Maria Müller

    2015-01-01

    Full Text Available Nitrogen (N is the most limiting nutrient for corn production. Thereby, the goal of the paper was to evaluate inoculation methods of Azospirillum brasilense in order to partially supply N required by the crop. The experiment was carried out in Guarapuava, PR, Brasil, in 2011/2012 growing season. Randomized blocks with factorial 3 inoculation methods (seed treatment, planting furrow and non-inoculated control x 5 doses of nitrogen (0, 75, 150, 225 and 300kg ha-1 x 8 replications was used as the experimental design. Leaf are index, foliar nitrogen content, total chlorophyll, grains per ear and yield were evaluated. There was significant interaction between inoculation methods and nitrogen fertilization to leaf area index, but not for yield. Inoculation with the diazotrophic bacteria provided yield increase of 702kg ha-1 for inoculation in seeding furrow and 432kg ha-1 for inoculation in seed treatment compared to the control, but both treatments did not differ between each other. Furthermore, total chlorophyll, grains per ear and yield were positively affected, with quadratic response, by the nitrogen fertilization in broadcasting

  18. Nitrogen translocation in wheat inoculated with Azospirillum and fertilized with nitrogen

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    RODRIGUES OSMAR

    2000-01-01

    Full Text Available The productivity and the translocation of assimilates and nitrogen (N were compared after inoculation of wheat (Triticum aestivum L., cv. BR-23 seeds with two strains of Azospirillum brasilense (strains 245 and JA 04 under field conditions. The inoculation of wheat seeds was done with a peat inoculant at sowing time. Plant material for evaluations were collected at anthesis and maturity. No differences in grain yield and in the translocation of assimilates resulting from inoculation were detected. Differences were observed in relation to N rates (0, 15, and 60 kg ha-1. N content in the grain increased significantly in the bacteria-inoculated treatments in which N was not added. This increase in N content in the grain with inoculation was probably due to higher N uptake after anthesis without any significant contribution on the grain yield. Such increment was of 8.4 kg ha-1 of N representing 66% more N than in no inoculated treatment. Regardless of the inoculation and the rate of N applied, it was observed that about 70% of the N accumulated at anthesis was translocated from vegetative parts to the grain.

  19. Plant yield and nitrogen content of a digitgrass in response to azospirillum inoculation

    Energy Technology Data Exchange (ETDEWEB)

    Schank, S.C.; Weier, K.L.; MacRae, I.C.

    1981-02-01

    Two Australian soils, a vertisol (pH 6.8, 0.299% N) and a sandy yellow podzol (pH 6.2, 0.042% N), were used with digitgrass, Digitaria sp. X46-2 (PI 421785), in a growth room experiment. Comparisons were made between plants inoculated with live and autoclaved bacterial suspensions of Australian and Brazilian isolates of Azospirillum brasilense. Seedlings were inoculated on days 10 and 35. Acetylene-reducing activity was measured five times during the experiment. Dry matter yields of the digitgrass on the podzol (low N) inoculated with liver bacteria were 23% higher than those of the controls. On the vertisol (high N), yield increases from inoculation with live bacteria were 8.5%. The higher-yielding plants had significantly lower precent nitrogen, but when total nitrogen of the tops was calculated, the inoculated plants had a higher total N than did the controls (P = 0.04). Acetylene-reducing activity was variable in the experiment, ranging from 0.5 to 11.9 mu mol of C2H2 core -1 day -1. Live bacterial treatment induced a proliferation of roots, possible earlier maturity, higher percent dry matter, and a higher total N in the tops. (Refs. 21).

  20. Aislamiento e identificación de cepas de Azospirillum sp. en pasto guinea (Panicum maximum Jacq. del Valle del Cesar Isolation and identification of Azospirillum sp. in Guinea grass (Panicum maximum Jacq. of the Valle del Cesar

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    Diana M Cárdenas

    2010-09-01

    Full Text Available Se evaluó el efecto de factores ambientales del Valle del Cesar y el manejo agronómico del pasto guinea (Panicum maximum Jacq., sobre la población bacteriana del género Azospirillum en medios de cultivo semisólidos NFb y LGI, para lo cual se utilizó un diseño experimental en parcelas divididas con un arreglo factorial de 2 (épocas climáticas: lluvia y sequía x 2 (manejos agronómicos: agroecólogico y extractivo x 3 (muestras analizadas: suelo rizosférico, raíces y hojas. Los resultados no revelaron diferencias estadísticas significativas, lo que indica que esta bacteria puede mantener su población en condiciones de estrés por diferentes mecanismos fisiológicos. A partir de estas muestras se obtuvieron 16 aislamientos pertenecientes al género Azospirillum, a los cuales se les evaluó su actividad de reducción de acetileno como indicador de la fijación biológica de nitrógeno y su capacidad en la producción de compuestos indólicos como promotores del crecimiento vegetal. Se seleccionaron las cepas SRGM2, SRGM3 y SRGM4 obtenidas de muestras de suelo rizosférico de pasto guinea de la Estación Experimental Motilonia de Corpoica, municipio Agustín Codazzi, departamento del Cesar. Estos aislamientos se caracterizaron molecularmente por el gen 16S rRNA y según el análisis BLAST en la base de datos del GenBank y presentaron 93% de similitud con A. lipoferum (SRGM2 y SRGM3 y 94% con A. brasilense (SRGM4.The effect of environmental factors of the Valle del Cesar and the agronomic management of Guinea grass (Panicum maximum Jacq., on the bacterial population of the Azospirillum genus in semisolid NFb and LGI culture media was evaluated, for which an experimental design was used in divided plots with a 2 (climatic seasons: rainy and dry x 2 (agronomic managements: agroecological and extractive x 3 (analyzed samples: rhizospheric soil, roots and leaves factorial arrangement. The results did not reveal significant statistical

  1. Realocação de nitrogênio e de biomassa para os grãos, em trigo submetido a inoculação de Azospirillum Reallocation of nitrogen and biomass to the seeds in wheat inoculated with Azospirillum bacteria

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    AGOSTINHO DIRCEU DIDONET

    2000-02-01

    Full Text Available Estudou-se, em condições de campo, o efeito de inoculante turfoso em pó contendo bactérias do gênero Azospirillum no rendimento de grãos e na remobilização de N e de biomassa para os grãos de trigo (Triticum aestivum L., cultivar Embrapa 16. Usaram-se como inoculantes, a estirpe de Azospirillum brasilense 245 e o isolado 10 de Azospirillum lipoferum. Em cada tratamento de inoculação, e também sem inoculação, aplicaram-se diferentes doses de N em diferentes estádios de desenvolvimento das plantas, distribuídos em blocos ao acaso com parcelas subdivididas. Na antese e na maturação fisiológica, avaliaram-se o acúmulo de massa seca e N total nas diferentes partes da planta. Na colheita, além do rendimento de grãos, avaliaram-se também o índice de colheita para biomassa e para N, os principais componentes do rendimento e o teor de N total de grãos. Os resultados ainda preliminares evidenciaram que, mesmo não havendo efeito da inoculação no rendimento de grãos, houve um melhor alocamento de N e de biomassa para os grãos, resultando em maior massa de mil grãos e em menor quantidade de N restante na palha das plantas na maturação fisiológica. Esses efeitos resultaram de um menor número de espigas m-2, provavelmente devido à morte de afilhos, fator que determinou maior disponibilidade de N e de biomassa às espigas e grãos restantes.The effect of inoculating wheat (Triticum aestivum L. seeds, cultivar Embrapa 16, with powder peat inoculant containing Azospirillum bacteria on yield and remobilization of nitrogen and biomass was studied under field conditions. The strain of Azospirillum brasilense 245 and the isolate 10 of Azospirillum lipoferum were used as inoculants. Different rates of nitrogen were applied at varying stages of plant growth for each inoculated and non-inoculated treatment, distributed in blocks at random with split plots. The accumulation of dry matter and total nitrogen in plant parts was evaluated

  2. In vitro propagation of fraser photinia using Azospirillum-mediated root development.

    Science.gov (United States)

    Llorente, Berta E; Larraburu, Ezequiel E

    2013-01-01

    Fraser photinia (Photinia × fraseri Dress.) is a woody plant of high ornamental value. The traditional propagation system for photinia is by rooting apical cuttings using highly concentrated auxin treatments. However, photinia micropropagation is an effective alternative to traditional in vivo propagation which is affected by the seasonal supply of cuttings, the long time required to obtain new plants, and the difficulties in rooting some clones.A protocol for in vitro propagation of fraser photinia using the plant growth-promoting ability of some rhizobacteria is described here. Bacterial inoculation is a new tool in micropropagation protocols that improves plant development in in vitro culture. Shoots culture on a medium containing MS macro- and microelements, Gamborg's vitamins (BM), N (6)-benzyladenine (BA, 11.1 μM), and gibberellic acid (1.3 μM) produce well-established explants. Proliferation on BM medium supplemented with 4.4 μM BA results in four times the number of shoots per initial shoot that develops monthly. Consequently, there is a continuous supply of plant material since shoot production is independent of season. Azospirillum brasilense inoculation, after 49.2 μM indole-3-butyric acid pulse treatment, stimulates early rooting of photinia shoots and produces significant increase in root fresh and dry weights, root surface area, and shoot fresh and dry weights in comparison with controls. Furthermore, inoculated in vitro photinia plants show anatomical and morphological changes that might lead to better adaptation in ex vitro conditions after transplanting, compared with the control plants.

  3. Eficiência da azospirillum brasilense na fixação de nitrogênio em milho

    OpenAIRE

    Repke, Rodrigo Alberto [UNESP

    2013-01-01

    O milho é um dos cereais mais cultivados no mundo, porém apresenta desafios quanto ao manejo correto da adubação. Sua elevada demanda por nitrogênio tem sido a principal responsável por excessivas doses de fertilizantes nitrogenados sintéticos aplicados na cultura. Como consequência, há aumento no custo de produção da lavoura e impactos negativos ao meio ambiente. Dessa forma, é necessário estudar métodos alternativos que promovam o desenvolvimento das plantas e garantam a produtividade, busc...

  4. Computer simulation and experimental study of the polysaccharide-polysaccharide interaction in the bacteria Azospirillum brasilense Sp245

    Science.gov (United States)

    Arefeva, Oksana A.; Kuznetsov, Pavel E.; Tolmachev, Sergey A.; Kupadze, Machammad S.; Khlebtsov, Boris N.; Rogacheva, Svetlana M.

    2003-09-01

    We have studied the conformational properties and molecular dynamics of polysaccharides by using molecular modeling methods. Theoretical and experimental results of polysaccharide-polysaccharide interactions are described.

  5. Biological response of Azospirillum spp. to different types of stress

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    Carlos Alberto Sangoquiza Caiza

    2018-01-01

    Full Text Available Azospirillum is one of the most studied free-living rhizobacteria currently of great agricultural interest because of its ability to bind biological nitrogen and produce phytohormones. The present research aimed at the biological response of Azospirillum spp. facing different types of stress. For this purpose, the micro and macro morphological characterization of Azospirillum spp. And its biological response to stress temperature, pH, salinity. The results revealed that the isolates (C2, C3 and C4 of Azospirillum spp. Grow in greater abundance at temperatures between 28-38 °C and pH between 7-8. The C2 and C3 isolates showed good growth up to 3.5 % (m / v NaCl, whereas the C4 strain was less tolerant. These results have biotechnological applicability and are of great importance when defining and controlling the mass production conditions of Azospirillum spp. for future formulations as biofertilizer in several crops of interest in Ecuador.

  6. The Effects of Carboxin-thiram on Associative Relationships between Azospirillum Species and Wheat (Chamran Cultivar

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    F. rejali

    2017-03-01

    Full Text Available Introduction: Biofertilizers have been identified as alternative to chemical fertilizers to increase soil fertility and crop production in sustainable farming systems. One of the most useful kind of biofertilizers include plant growth promoting rhizobacteria (PGPR. Azospirillum is an associative rhizobacteria which can be very useful for plants such as wheat. It can help plant by fixing nitrogen through biological way, causing root development, plant strength improvement in primary phases, causing germination percent increment, improving plant tolerance in stress situations (drought, salinity, soil compaction and pathogens, secreting plant promoting hormones like cytokinin, Oxin and finally yield increment will be observable. Modern agriculture largely relies on the extensive application of agrochemicals, including inorganic fertilizers and pesticides. Although pesticides are important, their effects on nontarget organisms are of great concern because this poses a risk to the entire ecological system. The fungicides may also adversely affect the soil microflora, especially the types of microorganisms that can applied to seeds as bacterial inoculants. Considering useful effects of plant growth promoting rhizobacteria especially Azospirillum on Wheat, this study was done in order to survey interaction effects between fungicide and available biofertilizers in Iran market. Materials and Methods: Effect of carboxin tiram in 2 levels (applied, non-applied as fungicide, on efficacy of wheat plant (Chamran Cultivar and final crop yields under association conditions with 5 Azospirillum species (A.brasilense, A.lipoferum, A.halopraeferense, A.irakense, A.sp using powdery and liquid formulation were studied in a greenhouse test for four months in Soil and Water Research Institute.At first some properties of used soil, including soil texture, pH, EC,organic carbon and available soil K, P, Fe, Zn, Mn and Cu were measured by laboratory methods.Nutrient Broth

  7. Desempenho agronômico a campo de híbridos de milho inoculados com Azospirillum

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    Patricia Dörr de Quadros

    2014-04-01

    Full Text Available O uso de inoculantes na cultura do milho tem sido cada vez mais valorizado, em vista dos benefícios que pode trazer à cultura, como a fixação biológica do nitrogênio e o aumento da quantidade de raízes. Isto pode melhorar a absorção de água e nutrientes pela planta, contribuindo para o desenvolvimento do milho, principalmente em períodos de seca. Este estudo foi desenvolvido com o objetivo de avaliar, em condições de campo, as características agronômicas e o rendimento de grãos de híbridos de milho, inoculados, ou não, com uma mistura de três espécies de Azospirillum (A. brasilense, A. lipoferum, A. oryzae. Foram avaliados o teor relativo de clorofila nas folhas, a altura de planta, a senescência foliar, os componentes de rendimento de grãos, o teor de N, a matéria seca da parte aérea das plantas e o número mais provável de bactérias diazotróficas na rizosfera das plantas. A inoculação manteve o teor de clorofila significativamente maior até o estádio R3 das plantas, para os três híbridos testados, aumentou o rendimento da matéria seca da parte aérea, dos híbridos AS 1575 e SHS 5050, o peso de 1000 grãos, para o híbrido P32R48 e altura, para o AS 1575. Houve interação entre os genótipos de milho e as bactérias inoculadas, visto que, cada híbrido testado respondeu de forma diferente à inoculação. A inoculação de Azospirillum em milho demonstrou estimular o desenvolvimento das plantas no período vegetativo, aumentando a probabilidade de obter-se um estande de plantas uniforme, maior resistência ao estresse e maior concentração de clorofila nas folhas.

  8. Pemacuan Pertumbuhan Melon (Cucumis melo L. dengan Cendawan Mikoriza Arbuskula dan Bakteri Azospirillum sp.

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    Lady Diana Tetelepta

    2016-10-01

    Full Text Available ABSTRACTMelon (Cucumis melo L. is a high economic value horticultural crop that is cultivated in some regions of Indonesia under fertilization management. Application of inorganic fertilizer continuously can reduce soil microbial abundance. One of the soil microbial that promote plant growth is arbuscular mycorrhizal fungi (AMF and Azospirillum sp. The aim of this study was to analysed the effect of AMF and Azospirillum sp. in promoting growth and production of melon. The experiment was carried out in a greenhouse and was arranged in a completely randomized design with five replicates. Five treatments tested were: control, fertilized with NPK, inoculated with AMF, inoculated with Azospirillum sp., inoculated with AMF + Azospirillum sp. The results showed that the effect of AMF on root growth and shoot growth were similar to NPK fertilizer. Azospirillum sp. increased root growth. On the other side, the effect of Azospirillum sp. on shoot growth was similar to NPK fertilizer. However, AMF and Azospirillum sp. inoculation solely increased plant height, fruit weight, fruit diameter, flavor and length of fruit storage. Meanwhile, combination of AMF and Azospirillum sp. increased plant height, root growth, shoot growth, fruit weight, fruit diameter, flavor and length of fruit storage. This study revealed that application of AMF and Azospirillum sp. in melon cultivation was more effective and efficient than NPK fertilizer.Keywords: arbuscular mycorrhizal fungi, Azospirillum sp., Cucumis melo L.

  9. Pertumbuhan Padi Varietas Ciherang Setelah Diinokulasi dengan Azospirillum Mutan Multifungsi

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    Edy Listanto

    2016-08-01

    Full Text Available Modern agriculture is very closely related to the application of fertilizer to induce plants grow. The application of bio-fertilizers is expected to reduce the negative impact of chemical fertilizers. The purpose of this study was to determine the effect of multi-functional Azospirillum N2 fixation, P solubility and IAA production on the growth of Ciherang rice in pot experiment in greenhouse BB Biogen. The experiment treatment were 3 types of inoculation (non-inoculation, inoculation using wildtype Aj Bandung 6.4.1.2 and the mutant isolate of AJM 3.7.1.14 , and 4 levels of fertilizer application (non-fertilization, a quarter dose, a half dose, and the real dose of fertilization on rice in lowland. The Azospirillum isolates were used wildtype isolate Aj Bandung 6.4.1.2 and mutant isolate AJM 3.7.1.14 that was isolated and mutated using ethyl methanesulfonate (EMS in BB Biogen. Seeds of Ciherang rice were inoculated using Azospirillum at cell density 106 cell/ml in different seedling tray. After 14 days, the seedlings were transferred to planting pots which consist of 3 plants per pot. Parameters observed were plant height, number of tillers, number of panicles per hill, wet and dry weight of panicles per hill, weight of 100 seeds, N and P content of the stover. The results showed that both wild-Azospirillum and mutant inoculum had no effect on the vegetative growth of Ciherang, but showed significant effect on the number of panicle per hill, grain weight per hill and dry weight of seeds per panicle. The use of Azospirillum and N fertilizer combination affected the growth and rice yields, also reduced chemical fertilizer application.

  10. Screening on Gibberellic Acid Producing Activity of Azospirillum Isolates

    International Nuclear Information System (INIS)

    Shun Lai Ei; Khin Mya Lwin; Myo Myint

    2010-12-01

    Six strains of Azopirillum spp were isolated from rice, sugarcane, corn, maize, sunflower and pepper roots and screened the gibberellic acid productivity. Only three strains of Azospirillum species showed the activity and were indentified by cultural, biochemical and drug sensitivity patterns. Among them,one strain isolated from rice root can produce microbial gibberellic acid. It showed greenish yellow colour in chromatogram under UV absorption. This screening method was studied from 1 to 14 days incubation. Qualitative measurement of GA productivity was determined by thin layer chromatography.

  11. Estandarización de un medio de cultivo a partir de fuentes agroindustriales para la multiplicación de Azospirillum brasilense

    Directory of Open Access Journals (Sweden)

    Diego Rivera

    2012-07-01

    Full Text Available The Plackett-Burman statistical design was initially applied for Screening the most important nutritional variables (four carbon sources, two nitrogen sources, K2 HPO4 y MgSO4 and a trace elements solution affecting microorganism biomass production. Subsequently, a optimising the process by applied a BoxBehnken design for the most important factors tree. The results showed that biomass (UFC/mL production was strongly affected by nutritional and physico conditions of culture medium. The highest yield was obtained in the following conditions: 3g/L sucrose, 6,75 mL/L molasses, 0,77 mL/L glycerol, 14,42 mL/L soybean hydrolyzate, 0,848 g/L yeast hidrolyzate, 0,25 g/L K2 HPO4 , ⅗ aeration and shaking at 120 rpm 26 hours total fermentation time during which 1 x 109 UFC/mL were obtained.

  12. Plant root transcriptome profiling reveals a strain-dependent response during Azospirillum-rice cooperation

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    Benoît eDrogue

    2014-11-01

    Full Text Available Cooperation involving Plant Growth-Promoting Rhizobacteria results in improvements of plant growth and health. While pathogenic and symbiotic interactions are known to induce transcriptional changes for genes related to plant defence and development, little is known about the impact of phytostimulating rhizobacteria on plant gene expression. This study aims at identifying genes significantly regulated in rice roots upon Azospirillum inoculation, considering possible favored interaction between a strain and its original host cultivar. Genome-wide analyses of Oryza sativa japonica cultivars Cigalon and Nipponbare were performed, by using microarrays, seven days post inoculation with A. lipoferum 4B (isolated from Cigalon or Azospirillum sp. B510 (isolated from Nipponbare and compared to the respective non-inoculated condition. A total of 7,384 genes were significantly regulated, which represent about 16 % of total rice genes. A set of 34 genes is regulated by both Azospirillum strains in both cultivars, including a gene orthologous to PR10 of Brachypodium, and these could represent plant markers of Azospirillum-rice interactions. The results highlight a strain-dependent response of rice, with 83 % of the differentially expressed genes being classified as combination-specific. Whatever the combination, most of the differentially expressed genes are involved in primary metabolism, transport, regulation of transcription and protein fate. When considering genes involved in response to stress and plant defence, it appears that strain B510, a strain displaying endophytic properties, leads to the repression of a wider set of genes than strain 4B. Individual genotypic variations could be the most important driving force of rice roots gene expression upon Azospirillum inoculation. Strain-dependent transcriptional changes observed for genes related to auxin and ethylene signalling highlight the complexity of hormone signalling networks in the Azospirillum

  13. Results in the application of biofertilizers using Azospirillum and Mycorrhiza, in associations of horticultural crops under semi-greenhouse conditions

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    Dania Bárbara Núñez Sosa

    2013-01-01

    Full Text Available The current research was carried out in the greenhouse “La Condesa”, which belongs to the Empresa de Cultivos Varios “Lenin”, in Jovellanos, Matanzas province. Its main objective was to evaluate the effect of the application of biofertilizer (Azospirillum sp and Micorrizas in combinations of crops (lettuce and radish, or beet and radish. The research included four different treatments: witness, Micorrizas, Azospirillum, Azospirillum +Micorrizas. We used an at random block design. Data were processed after evaluating yields components by using the statistical software called Statgraphics, version 5.0. The research showed a positive response to the application of biofertilizers, resulting in a considerable increase of profits.

  14. Influence of Azospirillum spp. on the nitrogen supply of a gramineous host

    NARCIS (Netherlands)

    Christiansen - Weniger, C.

    1991-01-01

    The main objectives of this study were to identify factors that control the behaviour of Azospirillum in the rhizosphere of a gramineous plant in order to be able to optimize the association between the bacteria and the host plants in terms of nitrogen supply to the

  15. Gluconic acid production and phosphate solubilization by the plant growth-promoting bacterium Azospirillum spp.

    Science.gov (United States)

    Rodriguez, Hilda; Gonzalez, Tania; Goire, Isabel; Bashan, Yoav

    2004-11-01

    In vitro gluconic acid formation and phosphate solubilization from sparingly soluble phosphorus sources by two strains of the plant growth-promoting bacteria A. brasilense (Cd and 8-I) and one strain of A. lipoferum JA4 were studied. Strains of A. brasilense were capable of producing gluconic acid when grown in sparingly soluble calcium phosphate medium when their usual fructose carbon source is amended with glucose. At the same time, there is a reduction in pH of the medium and release of soluble phosphate. To a greater extent, gluconic acid production and pH reduction were observed for A. lipoferum JA4. For the three strains, clearing halos were detected on solid medium plates with calcium phosphate. This is the first report of in vitro gluconic acid production and direct phosphate solubilization by A. brasilense and the first report of P solubilization by A. lipoferum. This adds to the very broad spectrum of plant growth-promoting abilities of this genus.

  16. Azospirillum spp. from native forage grasses in Brazilian Pantanal floodplain: biodiversity and plant growth promotion potential.

    Science.gov (United States)

    Souza, Mayara S T; de Baura, Valter A; Santos, Sandra A; Fernandes-Júnior, Paulo Ivan; Reis Junior, Fábio B; Marques, Maria Rita; Paggi, Gecele Matos; da Silva Brasil, Marivaine

    2017-04-01

    A sustainable alternative to improve yield and the nutritive value of forage is the use of plant growth-promoting bacteria (PGPB) that release nutrients, synthesize plant hormones and protect against phytopathogens (among other mechanisms). Azospirillum genus is considered an important PGPB, due to the beneficial effects observed when inoculated in several plants. The aim of this study was to evaluate the diversity of new Azospirillum isolates and select bacteria according to the plant growth promotion ability in three forage species from the Brazilian Pantanal floodplain: Axonopus purpusii, Hymenachne amplexicaulis and Mesosetum chaseae. The identification of bacterial isolates was performed using specific primers for Azospirillum in PCR reactions and partial sequencing of the 16S rRNA and nifH genes. The isolates were evaluated in vitro considering biological nitrogen fixation (BNF) and indole-3-acetic acid (IAA) production. Based on the results of BNF and IAA, selected isolates and two reference strains were tested by inoculation. At 31 days after planting the plant height, shoot dry matter, shoot protein content and root volume were evaluated. All isolates were able to fix nitrogen and produce IAA, with values ranging from 25.86 to 51.26 mg N mL -1 and 107-1038 µmol L -1 , respectively. The inoculation of H. amplexicaulis and A. purpusii increased root volume and shoot dry matter. There were positive effects of Azospirillum inoculation on Mesosetum chaseae regarding plant height, shoot dry matter and root volume. Isolates MAY1, MAY3 and MAY12 were considered promising for subsequent inoculation studies in field conditions.

  17. Relative efficiency of Azotobacter and Azospirillum on yield and P utilization by wheat (Triticum Aestivum) with various N levels

    International Nuclear Information System (INIS)

    Aishwath, O.P.; Dravid, M.S.; Yadav, B.R.

    2002-01-01

    Efficiency of 32 P labelled single superphosphate along with N levels (0, 60, 80 and 120 kg/ha) and biofertilizers (Azotobacter and Azospirillum) was studied on wheat in Typic ustifluvent (saline phase) soil. Average grain and straw yield, total P uptake, per cent P derived by crop from applied phosphorus and its utilization in grain and straw increased either with Azospirillum or Azotobacter inoculation. However, the magnitude of increase in these attributes was of higher extent in presence of Azotobacter as compared to Azospirillum. The yield, uptake and utilization of P increased with increasing levels of N. Per cent Pdff was higher with all levels of N over control, whereas, it was at par with their successive levels. Interaction effect between levels of nitrogen and biofertilizers were also positive and significant at all levels of N with respect to yield and uptake of P, while per cent Pdff and its utilization by wheat was more pronounced at 60 and 80 kg N ha -1 in the presence of Azotobacter. Azospirillum was more effective at 60 kg of N than the other levels. Generally, Azotobacter performed better than the Azospirillum with respect to all parameters. (author)

  18. Changes in Nutrient Content of Root and Grain of Wheat Cultivars Inoculated by Azospirillum and Mycorrhiza

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    M. Jiriaie

    2016-02-01

    Full Text Available Introduction: Providing the nutritional requirements of agricultural crops by non-chemical resources is a new approach in the organic farming that has attracted the attention of both the researchers and the consumers in recent years. Therefore, it is highly important to find new fertilizer resources that are both economically able to provide the nutritional needs of the crop plants and have no adverse effects on the consumers and the environment. Materials and Methods: With this approach, an experiment was conducted in the research station of Shahid Chamran University of Ahvaz, Iran in 2012-13. The experimental design was factorial based on randomized complete blocks design with three replications. The treatments including Mycorrhizal fungi in three levels (i.e. no use of strain; use of Glomus intraradices strain; and use of Glomus mosseae strain, bacteria Azospirillum lipoferum in two-levels (i.e. non-inoculated and inoculated and wheat cultivars in three levels (i.e. Chamran; Dena; and Behrang. The measured parameters include the concentration of macronutrients (i.e. nitrogen, phosphorus and potassium and some micronutrients (i.e. zinc, iron and manganese in two part seed and the root of wheat. Results and Discussion: Surveying the elements content in the root and the grain indicated a significant and positive effect of the use the Azospirillum and Mycorrhiza to improve the concentration of the elements in wheat cultivars. However, the simultaneous use of these microorganisms led to an increase of the effects of their application on their assessed traits.Finally the highest concentration of N (2.21 present, P (0.50 present and Fe (33.88 mg.kg-1 were observed in the grain; the highest concentration of K (0.93 present and 0.54 present and Mn (43.11 and 23.63 mg.kg-1 were observed in the grain and root, respectively. Moreover, the highest concentration of Zn in the root (19.70 mg.kg-1 was obtained from inoculation of C.V Dena seeds with

  19. Improvement of endophytic Azospirillum colonization by co-inoculation with Cellulomonas Uda ATCC 491

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    Mohammad Javad Mehdipour Moghaddam

    2014-04-01

    Full Text Available Introduction: Most of the plant growth promoting rhizobacteria (PGPR such as Azopirillum if accompanied with strong cellulase producing bacteria such as Cellulomonas, their colonization may be increased and their host plants growth improved. Materials and methods: Six endophytic Azospirilla which isolated from three rice and three wheat cultivars and also one strain from commercial biofertilizer (Green Biotech Co., identified by biochemical tests and 16S rDNA analysis and were studied on the basis of cellulase, pectinase and auxin production and also their chemotaxis toward rice and wheat cultivars exudates was investigated. Two cellulase positive (A5 and A6 and two negative (A2 and A3 strains were selected and their interaction with C. uda ATCC 491 on auxin production and colonization on roots were compared. Results: This study showed that none of the strains had pectinase activity, but the strain isolated from rice had more Carboxy methyl cellulase (CMCase activity. Selected isolates and C. uda ATCC 491 showed chemotaxis toward roots exudates. In most of the isolates, rate of auxin production increased by coculture with C. uda ATCC 491. Also, it was determined that C. uda ATCC 491 promoted the colonization of Azospirillum without or with cellulase activity on rice and wheat roots, respectively. Discussion and conclusion: Co-inoculation Azospirillum with C. uda ATCC 491 improves plant root system due to stimulation or additive effect of auxin production and cellulase activity, followed by more uptakes of water and minerals by roots. Also, it raises the number of colonization niches for useful bacteria such as Azospirillum and finally quantitative and qualitative plant parameters.

  20. The evaluation of IAA-production ability in indigenous Azospirillum isolates and their growth promoting effects on sweet corn

    Directory of Open Access Journals (Sweden)

    mahdi arab

    2009-06-01

    Full Text Available It has been years that Azospirillum is known to promote plant growth. Phytohormone (especially Auxin production has the most important role in increasing the yield of inoculated plants. According to this, 60 strains of this genus were isolated, identified, and purified. This ability was evaluated in both qualitative and quantitative assays using colorimetric method and the effects of superior isolate on sweet corn were measured. Results revealed that the abundance and probability of the bacteria isolation is low and 17%. About 31.2% and 100% of Azospirillum strains were capable of producing IAA in qualitative and quantitative methods respectively. In greenhouse experiment, bacteria treatments had significant effects on corn fresh weight, total dry weight, root dry weight and total nitrogen and phosphorus content of the plant. This was considered to be as the result of more lateral root formation which enhances nutrition uptake. In conclusion, the green house results in respect to in vitro achievements show that fortunately it can be claimed that bacteria of the genus Azospirillum can be used widely for not only strategic gramineous plants like: corn, wheat, barely etc. but also for other useful plants. Key words: Azospirillum, Auxin, qualitative and quantitative methods, sweet corn.

  1. Penggunaan Azospirillum pada Tanah Masam dengan Aluminium Tinggi Terhadap Produksi dan Serapan Nitrogen Rumput Setaria splendida dan Chloris gayana

    Directory of Open Access Journals (Sweden)

    P.D.M.H. Karti

    2005-04-01

    Full Text Available High content of Al on the soil maybe harmful (toxic for plant. Red and yellow podzolic soil was marginal land that characterized by high Al content. Azospirillum is free living N fixing bacteria that can be associated with grass. This research was conducted to find the best yield of grass planted on the soil inoculated with Azospirillum. The research consisted of some steps; 1 soil sampling 2 laboratory research: bacterial isolation, isolate selection, standardized of population, content of IAA 3 pod experiment. Pod experiment in the glass house was designed in completely randomized design, that consisted of six treatments. The variables observed were dry mass production of shoot and root, nitrogen content of shoot and root, and nitrogen absorption. Four best isolates chosen were; SM Setaria, OBIS/BD, PO2 and PM2. Azospirillum isolates enhanced shoot and root production, nitrogen content and N total absorption of tolerance one (S. splendida. The susceptible (C. gayana, Azospirillum significantly enhanced shoot and root nitrogen content, but did not affect the growth, production and N total absorption. Root growth that was inhibited by Al toxicity, decreased the symbiotic capability of nitrogen fixing bacteria. PM2 isolate showed the best effect on production and quality of S. splendida as well as on C. gayana. This isolate will be used for future research. PM2 produces 6.4 ppm Indole Acetic Acid that promoted root growth.

  2. Characterization of Azotobacter from roots of a weed growing in ...

    African Journals Online (AJOL)

    asdf

    2012-06-05

    Jun 5, 2012 ... produced by Azospirillum brasilense and their effect on the growth of pearl millet (Pennisetum americanum L). Appl. Environ. Microbiol. 37: 1016-1024. Tilak KVBR, Sigh CS, Roy NK, Subba Rao NS (1982). Azospirillum brasilense and Azotobacter chrococum inoculum: Effect on yield of maize (Zea mays) ...

  3. KARAKTERISASI SIFAT-SIFAT BIOKIMIA EKSTRAK KASAR LIPASE EKSTRASELULER BAKTERI Azospirillum sp.PRD1

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    Santi Nur Handayani

    2011-11-01

    Full Text Available Enzim lipase mempunyai peranan penting dalam katalis berbagai reaksi industri satu diantaranya pembuatan flavor melalui reaksi esterifikasi. Lipase adalah biokatalis yang berperan besar dalam aplikasi bioteknologi, seperti dalam sintesis biopolimer, biodiesel, produksi obat, dan produksi flavor. Peningkatan penggunaan lipase untuk industri mendorong dilakukan penelitian untuk mendapatkan sumber-sumber lipase baru. Sumber lipase yang potensial salah satunya adalah bakteri Azospirillum sp.PRD1 dari isolat lokal Laboratorium Mikrobiologi, Fakultas Biologi Universitas Jenderal Soedirman. Tujuan penelitian adalah untuk mendapatkan ekstrak kasar lipase dan menentukan karakteristik sifat-sifat biokimiawinya. Metode yang digunakan antara lain peremajaan bakteri Azospirillum sp.PRD1, dan produksi inokulum, penentuan waktu produksi optimum dan fase pertumbuhan bakteri, ekstraksi dan produksi ekstrak kasar lipase dan penentuan karakteristik sifat-sifat biokimiawinya. Hasil penelitian diperoleh ekstrak kasar lipase dari inokulum berumur 7 jam dan medium produksi dengan induser minyak zaitun yang diinkubasi selama 3 jam memiliki aktivitas spesifik 7,0547 Unit/mg. Lipase ekstrak kasar optimum pada pH 7, suhu 40 oC dan waktu inkubasi selama 25 menit. Lipase merupakan metaloenzim dengan kofaktor Zn2+ , Mn2+, Hg2+, Ca2+, Co2+ and Mg2+.

  4. Survey the Effect of Mycorrhiza and Azospirillum of Wheat Cultivars Resistance in Yellow Rust

    Directory of Open Access Journals (Sweden)

    M. Jiriaie

    2017-01-01

    Full Text Available Introduction: Wheat is one of the major agricultural crops with respect to human nutrition. It is cultivated over a wide range of environments, because of wide adaptation to diverse environmental conditions. In Iran, 6.2 million hectares are under wheat cultivation, of which 33% is irrigated and 67% is rain-fed, the irrigated wheat growing areas (2 million hectares are located mostly in southern, central and east of Iran Production of crops is under the influence of plant genetic structure, environmental conditions and their interactions. Biotic and abiotic stresses are considered to lower production. Among the biotic stress, the fungal disease is the main factor limiting production of crop plants in hot and humid regions. Stripe rust was not a serious economic concern to the wheat industry for most of the 1990’s due to the use of resistant varieties. However, by 2003 it had developed into a significant issue, particularly as new path types evolved. Even in the dry years of 2003 and 2004, stripe rust cost growers significant income. Provide country's need for wheat as a strategic product, meanwhile, production is free from chemical fungicide is a high but achievable goal. So in order to achieve fertilizer and fungicide resources that in addition to having no adverse effects on consumers and the environment, has been economically able to provide nutrition need of crop plant, is very important. Materials and Methods: With this approach, to survey the effect of Mycorrhiza and Azospirillum in resistance to yellow rust in wheat cultivars, an experiment was conducted at the research station of the Shahid Chamran University of Ahvaz, Iran in 2012-13. The experimental design was factorial based on a randomized complete block design with three replications. The treatments include of Mycorrhiza fungi in three levels (without application of Mycorrhiza strain and using strain Glomus intraradices and Glomus mosseae, Azospirillum lipoferum bacterium in two

  5. Protein quantity and quality of safflower seed improved by NP fertilizer and rhizobacteria (Azospirillum and Azotobacter spp.

    Directory of Open Access Journals (Sweden)

    Asia eNosheen

    2016-02-01

    Full Text Available Protein is an essential part of human diet. The aim of present study was to improve the protein quality of safflower seed by the application of plant growth promoting rhizobacteria (PGPR in combination with conventional nitrogen and phosphate (NP fertilizers. The seeds of two safflower cultivar Thori and Saif-32, were inoculated with Azospirillum and Azotobacter and grown under field conditions. Protein content and quality was assessed by crude protein, amino acid analysis and SDS-PAGE. Seed crude protein and amino acids (metheonine, phenylanine and glutamic acid showed significant improvement (55%–1250% by Azotobacter supplemented with quarter dose of fertilizers (BTQ at P≤0.05. Additional protein bands were induced in Thori and Saif-32 by BTQ and BTH (Azotobacter supplemented with half dose of fertilizers respectively. The Azospirillum in combination with half dose of fertilizers (SPH and BTQ enhanced the indole acetic acid (90% and gibberellic acid (23%–27% contents in safflower leaf. Taken together, these data suggest that Azospirillum and Azotobacter along with significantly reduced (up to 75% use of NP fertilizers improved the quality and quantity of safflower seed protein.

  6. FTIR and Raman spectroscopic studies of selenium nanoparticles synthesised by the bacterium Azospirillum thiophilum

    Science.gov (United States)

    Tugarova, Anna V.; Mamchenkova, Polina V.; Dyatlova, Yulia A.; Kamnev, Alexander A.

    2018-03-01

    Vibrational (Fourier transform infrared (FTIR) and Raman) spectroscopic techniques can provide unique molecular-level information on the structural and compositional characteristics of complicated biological objects. Thus, their applications in microbiology and related fields are steadily increasing. In this communication, biogenic selenium nanoparticles (Se NPs) were obtained via selenite (SeO32-) reduction by the bacterium Azospirillum thiophilum (strain VKM B-2513) for the first time, using an original methodology for obtaining extracellular NPs. Dynamic light scattering (DLS) and transmission electron microscopy (TEM) showed the Se NPs to have average diameters within 160-250 nm; their zeta potential was measured to be minus 18.5 mV. Transmission FTIR spectra of the Se NPs separated from bacterial cells showed typical proteinacious, polysaccharide and lipid-related bands, in line with TEM data showing a thin layer covering the Se NPs surface. Raman spectra of dried Se NPs layer in the low-frequency region (under 500 cm-1 down to 150 cm-1) showed a single very strong band with a maximum at 250 cm-1 which, in line with its increased width (ca. 30 cm-1 at half intensity), can be attributed to amorphous elementary Se. Thus, a combination of FTIR and Raman spectroscopic approaches is highly informative in non-destructive analysis of structural and compositional properties of biogenic Se NPs.

  7. N-acyl-homoserine lactone-mediated quorum-sensing in Azospirillum: an exception rather than a rule.

    Science.gov (United States)

    Vial, Ludovic; Cuny, Caroline; Gluchoff-Fiasson, Katia; Comte, Gilles; Oger, Phil M; Faure, Denis; Dessaux, Yves; Bally, René; Wisniewski-Dyé, Florence

    2006-11-01

    Forty Azospirillum strains were tested for their ability to synthesize N-acyl-homoserine lactones (AHLs). AHL production was detected for four strains belonging to the lipoferum species and isolated from a rice rhizosphere. AHL molecules were structurally identified for two strains: Azospirillum lipoferum TVV3 produces 3O,C(8)-HSL (N-3-oxo-octanoyl-homoserine-lactone), C(8)-HSL (N-3-octanoyl-homoserine-lactone), 3O,C(10)-HSL (N-3-oxo-decanoyl-homoserine-lactone), 3OH,C(10)-HSL (N-3-hydroxy-decanoyl-homoserine-lactone) and C(10)-HSL (N-3-decanoyl-homoserine-lactone), whereas A. lipoferum B518 produced 3O,C(6)-HSL (N-3-oxo-hexanoyl-homoserine-lactone), C(6)-HSL (N-3-hexanoyl-homoserine-lactone), 3O,C(8)-HSL, 3OH,C(8)-HSL and C(8)-HSL. Genes involved in AHL production were characterized for A. lipoferum TVV3 by generating a genomic library and complementing an AHL-deficient strain with sensor capabilities. Those genes, designated alpI and alpR, were found to belong to the luxI and luxR families, respectively. When cloned in a suitable heterologous host, alpI and alpR could direct the synthesis of the five cognate AHLs present in A. lipoferum TVV3. These two adjacent genes were found to be located on a 85 kb plasmid. Southern hybridization experiments with probes alpI/R indicated that genes involved in AHL production in the three other AHL-producing strains were not closely related to alpI and alpR. This study demonstrates that AHL-based quorum-sensing is not widespread among the genus Azospirillum and could be found only in some A. lipoferum strains.

  8. Identificação de genes de Azospirillum amazonense diferencialmente expressos em resposta à disponibilidade de nitrogênio

    OpenAIRE

    Fernando Hayashi Sant Anna

    2007-01-01

    Bactérias do gênero Azospirillum possuem a capacidade de promover o crescimento vegetal através de mecanismos que não estão claramente elucidados. Contudo, essa característica é muito estudada, tendo em vista a possibilidade de utilizar esses microrganismos na agricultura em detrimento do uso indiscriminado de fertilizantes industriais, que poluem o meio ambiente. O solo é um ambiente altamente variável quanto à disponibilidade de nutrientes e quanto a fatores físico-químicos, por isso, bacté...

  9. Inoculation with Azospirillum sp. and Herbaspirillum sp. Bacteria Increases the Tolerance of Maize to Drought Stress.

    Science.gov (United States)

    Curá, José Alfredo; Franz, Diego Reinaldo; Filosofía, Julián Ezequiel; Balestrasse, Karina Beatríz; Burgueño, Lautaro Exequiel

    2017-07-26

    Stress drought is an important abiotic factor that leads to immense losses in crop yields around the world. Strategies are urgently needed to help plants adapt to drought in order to mitigate crop losses. Here we investigated the bioprotective effects of inoculating corn grown under drought conditions with two types of plant growth-promoting rhizobacteria (PGPR), A. brasilense , strain SP-7, and H. seropedicae , strain Z-152. Plants inoculated with the bacteria were grown in a greenhouse with perlite as a substrate. Two hydric conditions were tested: normal well-watered conditions and drought conditions. Compared to control non-inoculated plants, those that were inoculated with PGPR bacteria showed a higher tolerance to the negative effects of water stress in drought conditions, with higher biomass production; higher carbon, nitrogen, and chlorophyll levels; and lower levels of abscisic acid and ethylene, which are plant hormones that affect the stress response. The oxidative stress levels of these plants were similar to those of non-inoculated plants grown in well-watered conditions, showing fewer injuries to the cell membrane. We also noted higher relative water content in the vegetal tissue and better osmoregulation in drought conditions in inoculated plants, as reflected by significantly lower proline content. Finally, we observed lower gene expression of ZmVP14 in the inoculated plants; notably, ZmVP14 is involved in the biosynthesis of abscisic acid. Taken together, these results demonstrate that these bacteria could be used to help plants cope with the negative effects of drought stress conditions.

  10. COMPARATIVE EVALUATION OF CONVENTIONAL VERSUS RAPID METHODS FOR AMPLIFIABLE GENOMIC DNA ISOLATION OF CULTURED Azospirillum sp. JG3

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    Stalis Norma Ethica

    2013-12-01

    Full Text Available As an initial attempt to reveal genetic information of Azospirillum sp. JG3 strain, which is still absence despite of the strains' ability in producing valued enzymes, two groups of conventional methods: lysis-enzyme and column-kit; and two rapid methods: thermal disruption and intact colony were evaluated. The aim is to determine the most practical method for obtaining high-grade PCR product using degenerate primers as part of routine-basis protocols for studying the molecular genetics of the Azospirillal bacteria. The evaluation includes the assessment of electrophoresis gel visualization, pellet appearance, preparation time, and PCR result of extracted genomic DNA from each method. Our results confirmed that the conventional methods were more superior to the rapid methods in generating genomic DNA isolates visible on electrophoresis gel. However, modification made in the previously developed DNA isolation protocol giving the simplest and most rapid method of all methods used in this study for extracting PCR-amplifiable DNA of Azospirillum sp. JG3. Intact bacterial cells (intact colony loaded on electrophoresis gel could present genomic DNA band, but could not be completely amplified by PCR without thermal treatment. It can also be inferred from our result that the 3 to 5-min heating in dH2O step is critical for the pre-treatment of colony PCR of Azospirillal cells.

  11. Effects of Azospirillum lipoferum on seedling characteristics derived from sunflower (Helianthus annus L. seed water deficit conditions

    Directory of Open Access Journals (Sweden)

    H. Hadi

    2016-05-01

    Full Text Available Seedling characteristics of different sunflower (Helianthus annus L. cultivars under drought stress and inoculation with the Azospirillum lipoferum in a spilt-factorial layout based on randomized complete block design with three replications were evaluated. Treatments included dehydration stress (seed produced on maternal plants which irrigated after 60 (desirable irrigation, 120 (medium stress, 180 mm (severe stress evaporation from evaporation pan class A, different sunflower cultivars (Lakomka, Master, Favorite, Soor and Armavirosky and inoculation with bacteria (Azospirillum lipoferum and control. Bacteria allocated in the main plots and seeds which derived from dehydration stress conditions and different cultivars were allocated in sub plots as a factorial layout. Results showed that the time of seedling emergence, seedling vigor index, leaf petiole, stem and seedling dry weight were increased 14, 44, 30, 31, 22 and 27 percent by inoculating with bacteria, respectively. The percent of Seedling emergence of seeds derived from medium stress 48 percent was more than optimal irrigation conditions. Final appearance, speed of emergence, emergence index, dry weight and stamina seedling resulting from severe stress conditions were decreased compared with optimal irrigation. Seedling emergence of seeds derived from medium stress which inoculated with bacteria increased by 9 percent. Emergence speed index, appearance, stamina and seedling dry weights of seeds which inoculated with bacteria increased at medium and sever water stress. With consideration of the effect of dehydration stress on germination and seedling emergence, seed inoculation with bacteria improved seedling emergence and seedling vigor of seeds derived from dehydration stress conditions.

  12. Nodulation of legumes, nitrogenase activity of roots and occurrence of nitrogen-fixing Azospirillum spp. In representative soils of central Amazonia

    Energy Technology Data Exchange (ETDEWEB)

    Sylvester-Bradley, R; De Oliverira, L A; De Podesta Filho, J A; John, T V

    1980-12-01

    Leguminosae do not predominate in the Brazilian Amazon rain forest, although they are among the five best represented families. Plant roots from various soils were examined for the presence of nodules, acetylene-reducing activity and N/sub 2/-fixing Azospirillum spp. Abundant nodulation was found in black earth (''terra preta dos indios'') and in one case on sandy soil under campinarana vegetation along a tributary of the upper Rio Negro. In sandy latosol some nodules occurred in secondary forest and fewer in primary forest. Legumes in disturbed clayey or sandy latosol showed more frequent nodulation. Primary forest on alluvial (''varzea'') soil, and in Bahia coastal rain forest on sandy latosol and Erythrina glauca used for shading cacao plantations were abundantly nodulated. Acetylene reduction assays showed no, or very little, nitrogenase activity of roots from primary or secondary forest on clayey latosol near Manaus. Nodulated roots from secondary forest on sandy latosol showed acetylene-reducing activity. High rates of acetylene reduction were observed in nodulated roots of primary forest on alluvial ''varzea'' soil. Root samples showed ethylene absorption in controls without acetylene which might interfere with the results of acetylene reduction tests. The incidence of Azospirillum was also higher in black earth than the other soils examined, and in soils with higher pH. The hypothesis that Azospirillum is associated with Trema micantha roots was refuted. Roots and soils collected under cultivated grasses showed a higher incidence of Azospirillum when fertilized with phosphorus and lime. Results indicate that nitrogen fixation did occur in association with roots in some soils, but not with roots of primary or secondary forest on clayey latosol in the vicinity of Manaus, which is the most common soil in Central Amazonia. The possible reasons for this are discussed.

  13. Effect of Nitrogen and Zinc Sulphate Fertilizers and Azotobacter and Azospirillum Biofertilizer on Yield and Growth Traits of Rapeseed (Brassica napus L.

    Directory of Open Access Journals (Sweden)

    N. Jafari

    2013-06-01

    Full Text Available In order to study the effects of simultaneous application of nitrogen (N and ZnSO4 fertilizers and biofertilizer (Azotobacter and Azospirillum on grain yield and growth traits of rapeseed, Hyola308 cultivar, a field experiment, with split plot factorial layout based on randomized complete blocks design with three replications, was conducted at Research Field of Faculty of Agriculture, University of Guilan, Rasht, Iran, during 2007-2008 growing season. Nitrogen fertilizer at four levels (0, 50, 100 and 150 kg/ha were the main plot and ZnSO4 fertilizer at two levels (0 and 50 kg/ha and biofertilizer at two levels (with and without biofertilizer were arranged in sub-plots. Results showed that maximum and minimum leaf area indices at flowering stage (average of 1.29 and 0.95, respectively were obtained in 150 kg/ha N+ZnSO4+ biofertilizer and in 50 kg/ha N+ no ZnSO4+ no biofertilizer treatments. Maximum and minimum crop growth rates at flowering stage (average of 5.89 and 3.19 g/m2.GDD, respectively were obtained in 150 kg/ha N+ZnSO4+ biofertilizer and control treatments. Maximum and minimum grain yields (2568, 2468 and 543 kg/ha, respectively were obtained in 150 kg/ha N+ with/without ZnSO4+ biofertilizer and control (no fertilizer treatments. Maximum and minimum oil yields (42.8 and 37.3%, respectively were measured in 0 kg/ha N+ZnSO4+ biofertilizer and 150 kg/ha N+ no ZnSO4+ no biofertilizer treatments. Since there was no significant difference between 150 and 100 kg/ha N+ZnSO4+ biofertilizer treatments in terms of impact on canola grain yield and growth traits, it seems that application of biofertilizer (Azotobacter and Azospirillum, without any reduction in yield, increased grain production and oil content and saved 50 kg/ha of N fertilizer. Biofertilizer (Azotobacter and Azospirillum, along with zinc and sulfur, produced phytohormones, and N fertilizer increased dry matter accumulation and leaf area index (by increasing carbohydrate conversion

  14. Detecção de Azospirillum amazonense em raízes e rizosfera de orchidaceae e de outras famílias vegetais

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    A. Lange

    2002-06-01

    Full Text Available Azospirillum amazonense é uma bactéria fixadora de N2 atmosférico de ampla ocorrência, principalmente em associações radiculares com gramíneas e palmeiras. Para verificar sua presença em outras espécies vegetais, ainda não estudadas, e a eficiência de meios para sua detecção, foram testados os meios Fam e LGI para contagens em solo rizosférico ou em culturas de enriquecimento com solo rizosférico, ecto e endorrizosfera. A. amazonense foi detectada no solo rizosférico, ecto e endorrizosfera de várias espécies de monocotiledôneas, incluindo Orchidaceae e dicotiledôneas, sendo o meio Fam mais eficiente para sua detecção

  15. Economic analysis of nitrogen fertilization in winter bean plant under no-tillage system

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    Michelle Traete Sabundjian

    2014-09-01

    Full Text Available With the expansion and diversity of the no-tillage system, it is necessary to evaluate the economic benefits generated throughout the production cycle, especially those related to remnants of previous crops and nitrogen fertilizer management of succeeding crops. This study aimed to evaluate the economic viability of four cover nitrogen doses on winter bean grain yield grown under no-tillage system after different crops. The experimental design was randomized blocks with four replications, in a 8x4 factorial scheme, with 32 treatments consisting of a combination of crop remnants (mayze; mayze - Azospirillum brasilense; Urochloa ruziziensis; Urochloa ruziziensis - Azospirillum brasilense; mayze + U. ruziziensis; mayze -A. brasilense + U. ruziziensis; mayze + U. ruziziensis - A. brasilense; mayze -A. brasilense + U. ruziziensis - A. brasilense and cover nitrogen doses (0 kg ha-1, 30 kg ha-1, 60 kg ha-1 and 90 kg ha-1. It was possible to conclude that the highest grain yield of winter bean plants irrigated by aspersion was obtained with the use of 90 kg ha-1 of cover nitrogen in succession to Urochloa ruziziensis without the inoculation of Azospirillum brasilense. In order to improve profits, it is recommended to apply 90 kg ha-1 of cover nitrogen to bean crops succeeding the other crops, except for inoculated Urochloa ruziziensis.

  16. Restrição do 16S-23S DNAr intergênico para avaliação da diversidade de Azospirillum amazonense isolado de Brachiaria spp. Restriction of 16S-23S intergenic rDNA for diversity evaluation of Azospirillum amazonense isolated from different Brachiaria spp.

    Directory of Open Access Journals (Sweden)

    Fábio Bueno dos Reis Junior

    2006-03-01

    Full Text Available O objetivo deste trabalho foi avaliar a diversidade intra-específica de isolados de Azospirillum amazonense e estabelecer a possível influência de diferentes espécies de Brachiaria ssp. e diferentes condições edafoclimáticas. A caracterização da diversidade desses isolados foi conduzida, utilizando-se a análise de restrição da região intergênica 16S-23S DNAr. As estirpes estudadas separaram-se em dois grupos, definidos a 56% de similaridade. As espécies de Brachiaria ssp. influenciaram a diversidade de estirpes. A maioria dos isolados oriundos de B. decumbens e B. brizantha está inserida no primeiro grupo, enquanto os oriundos de B. humidicola concentram-se no segundo grupo.The aim of this work was to study the intra-specific diversity of Azospirillum amazonense isolates and to establish possible influences of different Brachiaria spp. and edaphoclimatic conditions. The characterization of the diversity among the isolates of A. amazonense studied was conducted using restriction analysis of the 16S-23S rDNA intergenic spacer region. The evaluated strains were separated in two groups, defined at 56% of similarity. Brachiaria spp. showed effects on strain diversity. Most part of the isolates from B. decumbens and B. brizantha are inserted in the first group, while B. humidicola isolates concentrate in the second group.

  17. Response of rice to inoculation with plant growth promoting rhizobacteria in control lab environment and field experiment

    International Nuclear Information System (INIS)

    Ahmed, B.

    2014-01-01

    The present study was conducted to evaluate the effects of bacterial inoculation on different growth parameters of rice variety JP-5. Three bacterial strains (Azospirillum brasilense R1, Azospirillum lipoferum RSWT1 and Pseudomonas Ky1) were used to inoculate rice varietyJP-5 at control lab environment and field. Plant growth promotion was observed in all inoculated treatments over non-inoculated, which was evident from increase in root area, root length, number of tillers, straw and grain yields and total weight of plant. Azospirillum brasilense R1 was more effective in plant growth promotion than other strains and showed 19% increase in the straw weight and 39.5% increase in grain weight. Inoculation with Azospirillum lipoferum RSWT1 and Pseudomonas Ky1 increased grain weight by 18.5% and 13.8% respectively. The study revealed that beneficial strains of PGPR can be used as biofertilizer for rice. (author)

  18. Search for endophytic diazotrophs in barley seeds

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    Myriam S. Zawoznik

    2014-06-01

    Full Text Available Eight endophytic isolates assigned to Pseudomonas, Azospirillum, and Bacillus genera according to pheno-genotypic features were retrieved from barley seeds under selective pressure for nitrogen-fixers. Genetic relationships among related isolates were investigated through RAPD. Six isolates displayed nitrogen-fixing ability, while all could biosynthesize indolacetic acid in vitro and showed no antibiosis effects against Azospirillum brasilense Az39, a recognized PGPR.

  19. Aislamiento e identificación de cepas de Azospirillum sp. y evaluación de su capacidad para suplir las necesidades de nitrógeno en el cultivo de maíz (Zea mays) semihidroponico con dos sustratos diferentes bajo invernadero. Quito, Cayambe, Ecuador 2011.

    OpenAIRE

    Reyes Campaña, Alex Ramiro

    2011-01-01

    The corn, (Zea mays) L. is a basic crop in ecuadorian agriculture, which is why the search for environmentally friendly nitrogen fertilization of low cost doesn’t cease to be important. One of these options is the use of bio-fertilizers, for which the nitrogen fixing bacteria Azospirillum sp. can be used. The objective of this work is to isolate and identify Azospirillum sp. stumps, and evaluate its capacity to provide the nitrogen’s needs in the semi-hydroponic crop, , (Zea mays) L. withi...

  20. EFECT OF THE INOCULATION OF Rhodococcus fascians AND Azospirillum halopraeferens IN GERMINATION OF PALO FIERRO (Olneya tesota A. Gray UNDER GREENHOUSE CONDITIONS

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    Edgar Omar Rueda Puente

    2017-05-01

    Full Text Available The growth-promoting bacteria in plants (BGPB are a group of different species of bacteria can increase plant growth and productivity. Which can benefit plants through their own bacterial metabolism (phosphate solubilizing, producing hormones or fixing nitrogen. At present, desertification is a growing phenomenon worldwide, afforestation is one of the common solutions to combat this problem. Trees for reforestation are initially grown in greenhouses or nurseries. Among numerous reforestation practices, there is an alternative that inoculation with PGPB. Is a forest species that is endemic Olneya tesota Sonoran Desert, which is in danger of extinction. The objective was to evaluate the effect of bacteria growth promoter in plants with Rhodococcuis fascians and Azospirillum halopraeferens on germination and emergence of Ironwood under four salt concentrations (0, 0.25, 0.5 and 0.75 M NaCl under greenhouse conditions. Were obtained ironwood seeds in the region of Santa Ana, Sonora. Under greenhouse conditions was evaluated emergence percentage, germination rate, height, plant root length, fresh and dry weight of plant, number of bacterial cells attached to the root system, fresh and dry weight of the root. The results indicate that the germination percentage and other variables evaluated decreased as salinity increases. However, these changed positively to inoculation with bacteria R. fascians and A. halopraeferens.

  1. Enzymology of biological nitrogen fixation

    Energy Technology Data Exchange (ETDEWEB)

    Burris, R.H.

    1992-01-01

    Two genes involved in the regulation of nitrogenase activity, draT and draG, were cloned and found to be contiguous on the Azospirillum brasilense chromosome. The nifH gene, encoding dinitrogenase reductase, is near to draT with an intervening gap of 1.9 kb. The organization of these genes in Azospirillum lipoferum and Rhodosprillum rubrum is similar, but nifH and draT are separated by only 400 bp in the organisms. A. brasilense draTG is very similar to draTG in R. rubrum with 91.8% similarity and 85.3% identity at the amino acid level. Apparently A. brasilense uses the normal ATG initiation codon for draT, and draG. The genes for A. brasilense were able to restore function to appropriate mutants of R. rubrum. The heterologous expression of A. brasilense draTG in R. rubrum was not fully normal, as it responded more slowly to darkness and more quickly to ammonia than wild type cells. Our mutational analysis of the draTG region of A. brasilense confirms the function of these genes in the regulation of nitrogenase activity, but it also revealed minor but demonstrable differences in the control systems of R. rubrum and A. brasilense.

  2. Enzymology of biological nitrogen fixation. Annual report

    Energy Technology Data Exchange (ETDEWEB)

    Burris, R.H.

    1992-05-01

    Two genes involved in the regulation of nitrogenase activity, draT and draG, were cloned and found to be contiguous on the Azospirillum brasilense chromosome. The nifH gene, encoding dinitrogenase reductase, is near to draT with an intervening gap of 1.9 kb. The organization of these genes in Azospirillum lipoferum and Rhodosprillum rubrum is similar, but nifH and draT are separated by only 400 bp in the organisms. A. brasilense draTG is very similar to draTG in R. rubrum with 91.8% similarity and 85.3% identity at the amino acid level. Apparently A. brasilense uses the normal ATG initiation codon for draT, and draG. The genes for A. brasilense were able to restore function to appropriate mutants of R. rubrum. The heterologous expression of A. brasilense draTG in R. rubrum was not fully normal, as it responded more slowly to darkness and more quickly to ammonia than wild type cells. Our mutational analysis of the draTG region of A. brasilense confirms the function of these genes in the regulation of nitrogenase activity, but it also revealed minor but demonstrable differences in the control systems of R. rubrum and A. brasilense.

  3. Role of bioinoculants in development of salt-tolerance of Vicia faba ...

    African Journals Online (AJOL)

    Through biological inoculation technology, the bacterial-mycorrhizal-legume tripartite symbiosis in saline conditions was documented and the effects of dual inoculation with Azospirillum brasilense (NFB) and Arbuscular mycorrhizal (Am) fungus Glomus clarum on the host plants (Vicia faba) in pot cultures were investigated ...

  4. African Journal of Biotechnology - Vol 14, No 33 (2015)

    African Journals Online (AJOL)

    Polymers selection for a liquid inoculant of Azospirillum brasilense based on the Arrhenius thermodynamic model · EMAIL FREE FULL TEXT EMAIL FREE FULL TEXT · DOWNLOAD FULL TEXT DOWNLOAD FULL TEXT. S Cortés-Patiño, RR Bonilla, 2547-2553 ...

  5. African Journal of Biotechnology - Vol 13, No 49 (2014)

    African Journals Online (AJOL)

    Synergistic action of Azospirillum brasilense combined with thiamethoxam on the physiological quality of maize seedlings · EMAIL FREE FULL TEXT EMAIL FREE FULL TEXT DOWNLOAD FULL TEXT DOWNLOAD FULL TEXT. AG Battistus, TL Hachmann, TM Mioranza, MA Muller, T Madalosso, PA Favorito, VF Guimaraes, ...

  6. S Synerg with istic ac thiam ction o ethoxa of Azos am on maize ...

    African Journals Online (AJOL)

    sunny

    inoculation with Azospirillum brasilense strain AbV5, as well as the effect of the insecticide on the bacterial population. MATERIALS AND METHODS. The work was developed in the Laboratory of Plant Physiology and. Laboratory of Phytopathology, State University of West Paraná –. Unioeste, Campus Marechal Cândido ...

  7. F ield ef Serra fficacy atia ent of ino tomop organic hila AB K c carrie ...

    African Journals Online (AJOL)

    SAM

    Muthamilan, 1995) and Azospirillum brasilense (Saleh et al., 2001). The formulations of fluorescent Pseudomonas strain R62 and R81 were used to increase significantly plant growth and productivity in field condition (Sarma et al., 2009a). Broadcasting of talcum based formulation of. P. flurescens strains (Pf1 and FP7) on ...

  8. PHYSIOLOGICAL QUALITY OF CORN SEEDS REINOCULATED WITH DIAZOTROPHIC BACTERIA

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    Ricardo Felipe Braga de Sousa

    2015-09-01

    Full Text Available O objetivo deste trabalho foi avaliar a qualidade fisiológica de sementes de milho provenientes do cultivo associado com Azospirillum brasilense e Herbaspirillum seropedicae e reinoculadas com A. brasilense. As sementes utilizadas foram provenientes de cultivo em condições de campo, sendo os tratamentos: T1 - testemunha; T2 - 60 kg hectare-1 de N; T3 – inoculação (Azospirillum brasilense - AbV5; T4 - inoculação (Azospirillum brasilense + 60 kg hectare-1 de N; T5 - inoculação (Herbaspirillum seropedicae - SmR1 e T6 - inoculação (Herbaspirillum seropedicae + 60 kg hectare-1 de N. Foram separados dois lotes dos tratamentos, sendo um reinoculado com A. brasilense (AbV5. O delineamento foi inteiramente ao acaso com esquema fatorial (6x2, sendo seis tratamentos; com inoculação e reinoculadas. As sementes reinoculadas apresentaram maiores comprimentos, volumes e matéria seca de raízes e parte aérea, concluindo que a reinoculação com sementes promove um incremento no desenvolvimento inicial das plântulas.

  9. Identificação de isolados de Azospirillum amazonense associados a Brachiaria spp., em diferentes épocas e condições de cultivo e produção de fitormônio pela bactéria Identification of Azospirillum amazonense isolates associated to Brachiaria spp. at different stages and growth conditions, and bacterial plant hormone production

    Directory of Open Access Journals (Sweden)

    F. B. Reis Junior

    2004-02-01

    Full Text Available Existem evidências de que pastagens formadas por algumas espécies do gênero Brachiaria poderiam beneficiar-se com o processo de fixação biológica do nitrogênio atmosférico (FBN, garantindo a estas pastagens maior longevidade. Dentre as bactérias diazotróficas encontradas em associação com estas gramíneas forrageiras, destaca-se a espécie Azospirillum amazonense. Neste trabalho, objetivou-se verificar a influência da espécie de Brachiaria, manejo da pastagem e sazonalidade sobre as populações de A. amazonense associadas às raízes destas plantas. Diferentes pastagens (B. humidicola, B. decumbens e B. brizantha foram introduzidas em regiões do ecossistema Cerrado e de Mata Atlântica. Foram avaliados dois sistemas de manejo com diferentes taxas de lotação, e as coletas foram realizadas em diferentes épocas do ano. As populações de A. amazonense foram quantificadas e a identidade dos isolados confirmada, assim como sua capacidade de produção de fitormônios tipo AIA (ácido 3-indol acético em meio de cultivo. Isolados de A. amazonense foram obtidos a partir de amostras de raízes das três espécies de Brachiaria avaliadas. Estimativas das populações desta bactéria variaram de 10³-10(7 células g-1 de raízes. Em amostras do ecossistema Cerrado, a época de coleta apresentou efeito significativo sobre a população destas bactérias. Os dados da região de Mata Atlântica mostraram que plantas de Brachiaria de diferentes espécies e pastagens sob diferentes taxas de lotação podem apresentar números populacionais distintos associados às suas raízes. A técnica de análise de restrição do DNA ribossomal amplificado (ARDRA confirmou a identidade de todos os isolados avaliados. Estes isolados foram capazes de produzir fitormônios tipo AIA.There is evidence that pastures formed by some species of the genus Brachiaria could be benefited by the biological nitrogen fixation process (BNF, which would give these

  10. EFECTO DE LA INOCULACIÓN DE Azospirillum halopraeferens Y Bacillus amyloliquefaciens EN LA GERMINACIÓN DE Prosopis chilensis

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    J.A. Villegas-Espinoza

    2009-07-01

    Full Text Available Las Bacterias Promotoras de Crecimiento de Plantas (BPCP, son microorganismos fijadores de nitrógeno atmosférico y a su vez producen hormonas que aprovechan las plantas para llevar a cabo su desarrollo. Es importante la utilización de microorganismos benéficos para reducir la fertilización química. La investigación científica ha incrementado la busqueda y aislamiento de BPCP de regiones especificas como son las zonas áridas, ya que estos microorganismos estan adaptados a ambientes extremos. La especie Prosopis chilensis esta siendo utilizada para reforestación de escuelas, parques y también como ornato; para reproducir esta planta se esta utilizando fertilizantes químicos que son dañinos al medio ambiente. El objetivo de la presente investigación, consistió en analizar el efecto promotor de las bacterias promotoras del crecimiento vegetal Bacillus amyloliquefaciens y Azospirillum halopraeferens en la germinación y emergencia del mezquite chileno (P. chilensis bajo cuatro concentraciones salinas (0, 0.25, 0.5 y 0.75 M de NaCl. Se obtuvieron semillas de mezquite chileno de la región de Santa Ana, Sonora, México. Bajo condiciones de laboratorio se evaluó el porcentaje de germinación, tasa de germinación, altura, longitud radicular de plántula, peso fresco de plántula número de células bacterianas adheridas al sistema radicular. Bajo condiciones de invernadero, las variables evaluadas fueron porcentaje de emergencia, tasa de emergencia, altura y longitud radicular, peso fresco y seco de planta, peso fresco y seco de raíz, número de células bacterianas adheridas al sistema radicular. Los resultados indican que, bajo condiciones in vitro, el porcentaje y tasa de germinación disminuyó conforme la salinidad se incrementa. Sin embargo, estas variables fueron afectadas positivamente por A. halopraeferens y B. amyloliquefaciens en comparación del tratamiento

  11. Assessing the Effect of Organic Compounds, Biofertilizers and Chemical Fertilizers on Morphological Properties,yield and Yield Components of Forage Sorghum (Sorghum bicolor

    Directory of Open Access Journals (Sweden)

    A.H Saeidnejad

    2012-12-01

    Full Text Available Recently, using the source of organic fertilizers and biofertilizers in sustainable crop production is growing. In order to evaluate the effect of organic compounds, biofertilizers and chemical fertilizer on morphological properties, yield and yield components of forage Sorghum (sorghum bicolor a field experiment was conducted in the Research Farm, College of Agriculture, Ferdowsi University of Mashhad in 2008.The treatments were seed inoculation with the combination of Azotobacter chroococcum and Azospirillum brasilense, Compost (15 t/ha, Vermicompost (10 t/ha, seed inoculation with Azotobacter and Azospirillum and compost (10t/ha, seed inoculation with Azotobacter chroococcum and Azospirillum brasilense and Vermicompost (7t/ha, seed inoculation with Pseudomonas flurescence, seed inoculation with Pseudomonas flurescence and Azotobacter chroococcum and Azospirillum brasilense combination, seed inoculation with Pseudomonas flurescence and compost (15t/ha, chemical fertilizer (80 kg/h urea fertilizer and 50 kg/h super phosphate fertilizer and control. Harvesting was performed in 2 cuts in flowering stage. Plant height, number of tiller per plant and SPAD reading was significantly affected by the treatments. Stem diameter was not affected by any treatments. There was a significant difference among all treatments in terms of fresh and dry forage yield. There were no significant differences among all treatments in terms of stem and leaf dry matter. In general, result of this experiment indicated that organic amendments and biofertilizers could be acceptable alternatives for chemical fertilizers.

  12. INOCULACIÓN AL SUELO CON Pseudomonas fluorescens, Azospirillum oryzae, Bacillus subtilis Y MICROORGANISMOS DE MONTAÑA (MM Y SU EFECTO SOBRE UN SISTEMA DE ROTACIÓN SOYA-TOMATE BAJO CONDICIONES DE INVERNADERO

    Directory of Open Access Journals (Sweden)

    Leida Castro Barquero

    2015-01-01

    Full Text Available Se evaluó un sistema de rotación soya- tomate, con incorporación de biomasa verde y aplicación de inóculos microbianos individuales y en mezcla sobre el crecimiento de las plantas y propiedades edáficas; para ello se evaluaron en invernadero por 24 meses los siguientes 9 trata - mientos: solo tomate (T; rotación tomate-soya (TS; rotación tomate-soya con inoculaciones individuales de Azospirillum oryzae (A; de Pseudomonas fluorescens (P; de Bacillus sub - tilis (B; de microorganismos de montaña (MM; y las inoculaciones en mezcla de B. subtilis y P. fluorescens (BP; de B. subtilis, P. fluorescens y A. oryzae ( BPA; d e B. subtilis , P. fluorescens , Azospirillum sp. y MM (BPAMM. Se evalua - ron las variables físicas: densidad aparente y de partículas; conductividad hidráulica; poros totales; estabilidad de agregados; resistencia a la penetración (RP; las variables químicas: pH; conductividad eléctrica; contenido de N y C; relación C/N; contenido de nutrientes en suelos y foliares; las variables biológicas: respiración de suelos, unidades formadoras de colonias de hongos, bacterias y actinomicetos y el peso fres - co y seco foliar. Las variables físicas no fueron afectadas por los tratamientos, con excepción de RP, que fue mayor en el tratamiento T. Las varia - bles biológicas y químicas fueron sensibles a los tratamientos, con valores significativamente más altos en presencia de MM. Destaca el incremento del P en solución de suelo en tratamientos a los que se adicionó MM: pasó de 6 a 20 mg.l -1 ; esta condición se reflejó además en la cantidad de P en el tejido foliar al final del ensayo. Se determi - nó que el pH, CE y la respiración del suelo fueron afectados por la interacción entre los tratamientos aplicados y el tiempo transcurrido; los mayores valores se obtuvieron al final del ensayo y en los tratamientos con MM.

  13. Inoculación al suelo con Pseudomonas fluorescens, Azospirillum oryzae, Bacillus subtilis y microorganismos de montaña (mm y su efecto sobre un sistema de rotación soya-tomate bajo condiciones de invernadero

    Directory of Open Access Journals (Sweden)

    Leida Castro Barquero

    2015-11-01

    Full Text Available Se evaluó un sistema de rotación soyatomate, con incorporación de biomasa verde y aplicación de inóculos microbianos individuales y en mezcla sobre el crecimiento de las plantas y propiedades edáficas; para ello se evaluaron en invernadero por 24 meses los siguientes 9 tratamientos: solo tomate (T; rotación tomate-soya (TS; rotación tomate-soya con inoculaciones individuales de Azospirillum oryzae (A; de Pseudomonas fluorescens (P; de Bacillus subtilis (B; de microorganismos de montaña (MM; y las inoculaciones en mezcla de B. subtilis y P. fluorescens (BP; de B. subtilis, P. fluorescens y A. oryzae (BPA; de B. subtilis, P. fluorescens, Azospirillum sp. y MM (BPAMM. Se evaluaron las variables físicas: densidad aparente y de partículas; conductividad hidráulica; poros totales; estabilidad de agregados; resistencia a la penetración (RP; las variables químicas: pH; conductividad eléctrica; contenido de N y C; relación C/N; contenido de nutrientes en suelos y foliares; las variables biológicas: respiración de suelos, unidades formadoras de colonias de hongos, bacterias y actinomicetos y el peso fresco y seco foliar. Las variables físicas no fueron afectadas por los tratamientos, con excepción de RP, que fue mayor en el tratamiento T. Las variables biológicas y químicas fueron sensibles a los tratamientos, con valores significativamente más altos en presencia de MM. Destaca el incremento del P en solución de suelo en tratamientos a los que se adicionó MM: pasó de 6 a 20 mg.l-1; esta condición se reflejó además en la cantidad de P en el tejido foliar al final del ensayo. Se determinó que el pH, CE y la respiración del suelo fueron afectados por la interacción entre los tratamientos aplicados y el tiempo transcurrido; los mayores valores se obtuvieron al final del ensayo y en los tratamientos con MM.

  14. Studies on phosphorus utilization as influenced by bacterial seed inoculation and phosphorus fertilization in summer mung (Vigna radiata L. Wilczek)

    International Nuclear Information System (INIS)

    Kothari, S.K.; Saraf, C.S.

    1988-01-01

    A greenhouse experiment was conducted with four types of bacterial inoculation (Rhizobium alone; Rhizobium along with Azotobacter chroococcum; Rhizobium along with Azospirillum brasilense and no inoculation) and three levels of phosphorus ( 32 P labelled SSP) application (O, 6.5 ppm and 13.0 ppm P). Inoculation with Rhizobium along with Azotobacter chroococcum was found to be better than Rhizobium alone or Rhizobium along with Azospirillum brasilense in respect of leaf, stem, root and nodule dry weight, phosphorus uptake and utilization efficiency. P application upto 6.5 ppm significantly increased leaf, stem, root and nodule dry weight and phosphorus uptake. Per cent phosphorus derived from fertilizer (per cent pdff) and fertilizer P uptake significantly increased while P utilization efficiency significantly decreased with increasing levels of P application. (author). 12 refs., 2 tables

  15. Control of Herbaspirillum seropedicae NifA Activity by Ammonium Ions and Oxygen

    Science.gov (United States)

    Souza, E. M.; Pedrosa, F. O.; Drummond, M.; Rigo, L. U.; Yates, M. G.

    1999-01-01

    The activity of a truncated form of Herbaspirillum seropedicae NifA in different genetic backgrounds showed that its regulatory domain is involved in nitrogen control but not in O2 sensitivity or Fe dependence. The model for nitrogen control involving PII could thus apply to the proteobacteria at large. NifA may have a role in controlling ADP-ribosylation of nitrogenase in Azospirillum brasilense. PMID:9882688

  16. Optical methods for creating delivery systems of chemical compounds to plant roots

    Science.gov (United States)

    Kuznetsov, Pavel E.; Rogacheva, Svetlana M.; Arefeva, Oksana A.; Minin, Dmitryi V.; Tolmachev, Sergey A.; Kupadze, Machammad S.

    2004-08-01

    Spectrophotometric and fluorescence methods have been used for creation and investigation of various systems of target delivery of chemical compounds to roots of plants. The possibility of using liposomes, incrusted by polysaccharides of the external surface of nitrogen-fixing rizospheric bacteria Azospirillum brasilense SP 245, and nanoparticles incrusted by polysaccharides of wheat roots, as the named systems has been shown. The important role of polysaccharide-polysaccharide interaction in the adsorption processes of bacteria on wheat roots has been demonstrated.

  17. Microorganisms associated to tomato seedlings growing in saline culture act as osmoprotectant

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    Daniel Cortés-Jiménez

    2014-06-01

    Full Text Available Less than 0.5% of total water in the world is available for human consumption and agriculture. The major part of the world's water is saline and salinity in soils interferes in germination of seeds and the posterior development of the plant. In order to increase the osmotolerance of tomato, seedlings were associated with Azospirillum brasilense Cd, Azospirillum brasilense Cd transformed bacteria with a plasmid harboring a trehalose biosynthesis gene-fusion or Chlorella vulgaris. Two plant culture media: Hydroponic and Murashige and Skoog were tested. In the first set of studies seedlings were associated to single free cells meanwhile in a second set single and combined free cells were studied. A positive interaction between transformed Azospirillum and Chlorella vulagris and tomato plants was observed. Seedlings showed a salt concentration tolerance, as sodium chloride, up to 200 mM. According to our results, the association of plants with A. brasilense Cd-BIF and C. vulgaris is a viable approach to increase their salt tolerance and biomass, as consequence the possible use of sea water to irrigate horticultural plants.

  18. Use of Bio-Organic Fertilizers to Develop N Uptake Using 15N Technique

    International Nuclear Information System (INIS)

    Galal, Y.G.M.

    2008-01-01

    Experimental work either in field scale or in green house conditions were conducted using 15 N technique to evaluate the role of different bio fertilizers and different plant residues as organic amendments on enhancement of plant N nutrition. Nitrogen fixation by a symbiotic bacteria has been observed in greenhouse and field experiments under dry land cropping systems. Biological N 2 fixation associated with crop residues (legumes or cereals) was investigated in pot experiments with wheat and chickpea cultivars. In these experiments, labelled wheat and rice straw were used as organic N sources in comparison with either 15 N-labelled ammonium sulfate or ammonium nitrate as chemical nitrogen fertilizers. Rhizobium inoculation extended to be used with wheat gave the best results of N uptake and N 2 fixation when combined with Azospirillum brasilense as heterotrophic diazotrophs. The nitrogen uptake by wheat plants was significantly increased by application of soybean residues and inoculation with Azospirillum brasilense. From the field trial we can conclude that soybean residue as enriched N material, and Azospirillum brasilense inoculation enhanced N yields of wheat cultivars grown in poor fertile sandy soil

  19. PRODUTIVIDADE DA SOJA EM RESPOSTA Á INOCULAÇÃO PADRÃO E COINOCULAÇÃO

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    Ivana Marino Bárbaro

    2009-06-01

    Full Text Available The objectives of this research were to evaluate the response to a standard inoculation with Bradyrhizobium, as well as the co-inoculation with Azospirillum brasilense and Bradyrhizobium in soybean sown area already established with the culture. The rehearsal was installed in Colina-SP, in november of 2007, with the use of the soybean cultivar MG BR 46 (Conquista. The treatments were: 1 - control without N and without inoculation of Bradyrhizobium, 2-control with 200 kg N / ha split, 3-inoculation with Bradyrhizobium, 4-coinoculation with Bradyrhizobium and Azospirillum brasilense peat and 5 - co-inoculation with Bradyrhizobium and Azospirillum brasilense liquid. The experimental design was randomized blocks, with four replications. The experimental plots were constituted by six rows of four meters of length, with spacing of 0,50 m. In V6, were evaluated the nodulation, root dry mass and shoot dry mass. The crop was accomplished manually, in the useful area of the plot, being dear the yield of grains in kg/ha, after obtaining of the mass of grains for portion, being determined the text of water, calculated in 13% of humid base. Besides, the mass of the thousand seeds/plot was evaluated, in grams. In general, it was found that inoculation as well as the coinoculation did not cause an increase in most parameters assessed and soybean yield when grown in area already established with the culture, in Colina-SP.

  20. Maize response to inoculation with strains of plant growth-promoting bactéria

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    Janaína Dartora

    Full Text Available ABSTRACT The aim of this study was to evaluate the response of maize to inoculation with strains of plant growth-promoting bacteria (PGPB in two cultivation years. The experiment was set in a randomized block design with four replicates in two cultivation years (2012/13 and 2013/14. The treatments consisted of PGPB inoculation: control (without N and without inoculation; 30 kg of N ha-1 at sowing (N1; 160 kg of N ha-1 (N1 + 130 kg of N ha-1 as top-dressing; N1 + A. brasilense, Ab-V5; N1 + A. brasilense, HM053; N1 + Azospirillum sp. L26; N1 + Azospirillum sp. L27; N1 + Enhydrobacter sp. 4331; N1 + Rhizobium sp. 8121. Basal stem diameter, plant height, leaf area, shoot dry matter and yield were evaluated. The strain of Rhizobium sp. 8121and the isolate Azospirillum sp. L26 associated with 30 kg of N ha-1 at sowing promoted yields equivalent to that of the N fertilization of 160 kg ha-1, demonstrating the potential to be used in the inoculation of maize seeds.

  1. EFECTO DE LA BIOFERTILIZACIÓN SOBRE EL CRECIMIENTO EN MACETA DE PLANTAS DE CAÑA DE AZÚCAR (Saccharum officinarum EFEITO DA BIOFERTILIZAÇÃO NO CRESCIMENTO DE PLANTAS EM VASOS açúcar de cana (Saccharum officinarum EFFECT OF BIOFERTILIZATION ON THE GROWTH OF POTTED SUGARCANE PLANTS (Saccharum officinarum

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    LILIANA SERNA-COCK

    2011-12-01

    Full Text Available El uso de microorganismos como fertilizante, ha demostrado tener efectos benéficos sobre el crecimiento de plantas y son una alternativa al uso de fertilizantes guímicos, sin embargo, cada microorganismo difiere en sus efectos benéficos. En este trabajo se evaluó el efecto de la aplicación de microorganismos fertilizantes, Azospirillum brasilense, Azotobacter chroccocum y Trichoderma lignorum sobre el crecimiento en maceta de plantas de caña de azúcar variedad CC 934418. El crecimiento de las plantas se midió en términos de diámetro del tallo, longitud de tallo y raíces, y número de hojas y raíces a los 15, 30 y 45 días de la siembra. El crecimiento de las plantas mostró diferencias estadísticamente significativas entre los tratamientos. Los microorganismos fertilizantes mostraron efecto positivo sobre el crecimiento de plantas de caña de azúcar, siendo Azospirillum brasilense y Trichoderma lignorum los microorganismos gue ejercieron mayor efecto sobre el diámetro del tallo y los sistemas radical y foliar de la planta. Se observaron los efectos beneficiosos de Trichoderma lignorum sobre el crecimiento de la hoja. Este es un nuevo aporte científico, ya que esta especie no ha sido reportada como promotora de crecimiento vegetal.0 uso de microrganismos como fertilizante, tem sido demonstrado gue têm efeitos benéficos no crescimento das plantas e são considerados uma alternativa ao uso de fertilizantes guímicos, no entanto, cada microrganismo possui diferentes efeitos benéficos. Neste estudo foi avaliado o efeito da aplicação de microorganismos fertilizantes, Azospirillum brasilense, Azotobacter chroccocum e Trichoderma lignorum no crescimento de cana-de-açucar da variedade CC 934418 plantadas em vasos. 0 crescimento das plantas foi medido em termos do diâmetro do caule, comprimento de caule e da raiz e número de folhas e raízes nos dias 15, 30 e 45 após a semeadura. 0 crescimento da planta mostrou diferen

  2. Efecto de la biofertilización y los biorreguladores en la germinación y el crecimiento de Carica papaya L.

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    Maricela Constantino

    2010-07-01

    Full Text Available Título en inglés: Effect of biofertilization and bioregulators on germination and growth of Carica papaya L. Resumen Con el objetivo de incrementar y acelerar el proceso de germinación de las semillas y obtener una alta producción y homogeneidad de plántulas de Carica papaya variedad Maradol en vivero, se evaluó el efecto de tres biofertilizantes aplicados solos o en combinación (Azotobacter chroococcum, Azospirillum brasilense y Glomus intraradices, y un biorregulador del crecimiento vegetal, el ácido giberélico (AG3, en la germinación y el crecimiento vegetal. Se realizó un experimento bajo un diseño completamente al azar con ocho tratamientos y tres repeticiones. A las semillas se les aplicó un pretratamiento germinativo con alternancia de temperatura para superar la dormancia. Los tratamientos simples con A. chroococcum y A. brasilense, incrementaron el porcentaje de germinación a 90,28 y 88,89% respectivamente. Además, con la aplicación de los biofertilizantes y el AG3, la velocidad de germinación se incrementó y el tiempo medio de germinación se redujo. La doble aplicación en semillas y foliar de los biofertilizantes y el AG3 en plántulas mejoró el crecimiento vegetal. La población de A. chroococcum fue mayor cuando se inoculó en combinación con G. intraradices. La prevalencia de colonización de las plántulas inoculadas con G. intraradices varió de 18,53 a 26,67%, con el mayor valor registrado para el tratamiento combinado con A. brasilense. Finalmente, aplicando esta metodología se logró acelerar la germinación, obteniéndose una mayor homogeneidad en la emergencia de las plántulas, disminuyendo así el tiempo de permanencia en el vivero. Palabras clave: Azospirillum brasilense; Azotobacter chroococcum; Glomus intraradices; ácido giberélico; dormancia. Abstract In order to increase and accelerate the process of seed germination and obtain a high yield and homogeneity of papaya seedlings cv. Maradol in

  3. Enhancement of Chlorella vulgaris growth and bioremediation ability of aquarium wastewater using diazotrophs.

    Science.gov (United States)

    Ali, Sayeda Mohammed; Nasr, Hoda Shafeek; Abbas, Wafaa Tawfik

    2012-08-15

    Treatment of aquarium wastewater represents an important process to clean and recycle wastewater to be safely returned to the environment, used for cultivation or to minimize the multiple renewal of water. Chlorella vulgaris was an important freshwater microalgae which used in wastewater treatment, and increasing its potential of treatment can be achieved with existence of N2-fixing bacteria. Co-culturing of Chlorella vulgaris with the diazotrophs, Azospirillum brasilense or Azotobacter chroococcum in three different media; aquarium wastewater (AWW), sterile enriched natural aquarium wastewater (GPM) and synthetic wastewater media (SWW) were studied. Biomass yield of the microalgae was estimated by determination of chlorophylls (a and b), total carotenoid and the dry weight of C. vulgaris. Also determination of ammonia, nitrite, phosphate and nitrate in the culture were done. The presence of diazotrophs significantly increased the biomass of C. vulgaris by increasing its microalgae pigments (chlorophylls a and b, and total carotenoids). The highest pigments percentage was reported due to addition of A. brasilense to C. vulgaris (18.3-133.5%) compared to A. chroococcum (23.9-56.9%). As well as increased dry weight from 12 to 50%. There was also improved removal of nitrate, nitrite, ammonia and phosphate; where, the highest removal percentage was reported due to addition of A. chroococcum to C. vulgaris (0.0-52%) compared to A. brasilense (0.6-16.4%). A. brasilense and A. chroococcum can support C. vulgaris biomass production and bioremediation activity in the aquarium to minimize the periodical water renewal.

  4. EFFECT OF NITROGEN-FIXING BACTERIA ON GRAIN YIELD AND DEVELOPMENT OF FLOODED IRRIGATED RICE

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    AMAURI NELSON BEUTLER

    2016-01-01

    Full Text Available This study aimed at evaluating the effect of Azospirillum brasilense , a nitrogen - fixing bacterium, on flooded irrigated rice yield. Evaluations were carried out in a shaded nursery, with seedlings grown on an Alfisol. Were performed two sets of experiments. In the first, were carried out four experiments using the flooded rice cultivars INIA Olimar, Puitá Inta - CL, Br Irga 409 and Irga 424; these trials were set up as completely randomized design in a 5x4 factorial scheme, with four replications. Treatments consisted of five nitrogen rates (0, 40, 80, 120 and 160 kg ha - 1 and four levels of liquid inoculant Ab - V5 and Ab - V6 - A. brasilense (0, 1, 2 and 4 times the manufacturer's recommendation without seed treatment. In second set, were performed two experiments using the cultivars Puitá Inta - CL and Br Irga 409, arranged in the same design, but using a 4x2 factorial. In this set, treatments were composed of four levels of Ab - V5 and Ab - V6 - A. brasilense liquid inoculant (0, 1, 2 and 4 times the recommendation of 100 mL ha - 1 , using rice seeds with and without insecticide and fungicide treatment. Shoot dry matter, number of panicles, and rice grain yield per pot were the assessed variables. The results showed that rice seed inoculation with A. brasilense had no effects on rice grain yield of the cultivars INIA Olimar, Puitá Inta - CL, Br Irga 409 and Irga 424.

  5. [Immunochemical Detection of Azospirilla in Soil with Genus-Specific Antibodies].

    Science.gov (United States)

    Shirokov, A A; Krasov, A I; Selivanov, N Yu; Burygin, G L; Shchegolev, S Yu; Matora, L Yu

    2015-01-01

    Immunoelectrophoresis and immunodiffusion analysis with antibodies to whole intact cells of the type strain of nitrogen-fixing soil bacteria Azospirillum brasilense Sp7 revealed at least three conservative surface immunogenic proteins of azospirilla. Cross-reactions with these proteins made it possible to use the above antibodies for detection of azospirilla as a genus-specific probe conjugated with horseradish peroxidase as an enzymatic label. Direct immune-enzyme analysis of soil suspensions (typical chernozem, Saratov oblast) confirmed applicability of the conjugates based on genus-specific antibodies to the surface proteins of azospirilla for direct detection of this bacterial genus in environmental samples. These results provide a basis for broad application of this method for analysis of Azospirillum occurrence in soil.

  6. Molecular responses in root-associative rhizospheric bacteria to variations in plant exudates

    Science.gov (United States)

    Abdoun, Hamid; McMillan, Mary; Pereg, Lily

    2015-04-01

    Plant exudates are a major factor in the interface of plant-soil-microbe interactions and it is well documented that the microbial community structure in the rhizosphere is largely influenced by the particular exudates excreted by various plants. Azospirillum brasilense is a plant growth promoting rhizobacterium that is known to interact with a large number of plants, including important food crops. The regulatory gene flcA has an important role in this interaction as it controls morphological differentiation of the bacterium that is essential for attachment to root surfaces. Being a response regulatory gene, flcA mediates the response of the bacterial cell to signals from the surrounding rhizosphere. This makes this regulatory gene a good candidate for analysis of the response of bacteria to rhizospheric alterations, in this case, variations in root exudates. We will report on our studies on the response of Azospirillum, an ecologically, scientifically and agriculturally important bacterial genus, to variations in the rhizosphere.

  7. Increased root exudation of 14C-compounds by sorghum seedlings inoculated with nitrogen-fixing bacteria

    International Nuclear Information System (INIS)

    Lee, K.J.; Gaskins, M.H.

    1982-01-01

    Organic components leaked from Sorghum bicolor seedlings ('root exudates') were examined by recovering 14 C labelled compounds from root solutions of seedlings inoculated with Azospirillum brasilense, Azotobacter vinelandii or Klebsiella pneumoniae nif-. Up to 3.5% of the total 14 C recovered from shoots, roots, and nutrient solutions was found in the root solutions. Inoculation with Azospirillum and Azotobacter increased the amounts of 14 C and decreased the amounts of carbohydrates in the root solutions. When sucrose was added as a carbon source for the bacteria, the increase of 14 C in the solutions did not occur. Quantities of 14 C found in the root solutions were proportional to amounts of mineral nitrogen supplied to the plants. Bacterial growth also was proportional to nitrogen levels. When sorghum plants were grown in soil and labelled with 14 CO 2 , about 15% of the total 14 C recovered within 48 hours exposure was found in soil leachates. (orig.)

  8. Recent developments in the structural organization and regulation of nitrogen fixation genes in Herbaspirillum seropedicae.

    Science.gov (United States)

    Pedrosa, F O; Benelli, E M; Yates, M G; Wassem, R; Monteiro, R A; Klassen, G; Steffens, M B; Souza, E M; Chubatsu, L S; Rigo, L U

    2001-10-04

    Herbaspirillum seropedicae is a nitrogen-fixing bacterium found in association with economically important gramineae. Regulation of nitrogen fixation involves the transcriptional activator NifA protein. The regulation of NifA protein and its truncated mutant proteins is described and compared with that of other nitrogen fixation bacteria. Nitrogen fixation control in H. seropedicae, of the beta-subgroup of Proteobacteria, has regulatory features in common with Klebsiella pneumoniae, of the gamma-subgroup, at the level of nifA expression and with rhizobia and Azospirillum brasilense, of the alpha-subgroup, at the level of control of NifA by oxygen.

  9. Evaluación de la asociación bacterias fijadoras de nitrógeno - líneas interespecíficas de arroz-nitrógeno, en Typic haplustalf. Ibagué, Colombia Evaluation of the association nitrogen fixing bacterias interspecific - rice lines - nitrogen, in typic haplustalf. Ibagué, Colombia

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    Margarita M Vallejo

    2008-01-01

    Full Text Available El estudio se llevó a cabo en la hacienda Cauchitos, municipio de Ibagué, departamento del Tolima (Norte 4° 23' 51" y Oeste 75° 9' 7", 979 msnm, 24.3°C, bosque seco tropical (bs-T, con el objetivo de evaluar las asociaciones entre bacterias fijadoras de nitrógeno con inóculo y sin él en diez líneas interespecíficas de arroz, con tres dosis de nitrógeno (0%, 50% y 100% de 250 kg/ha-1 y tres repeticiones por tratamiento. La inoculación se realizó con 1 cm³ de unidades formadoras de colonias por 250 g de semilla de cada cultivar. Se aislaron 2.260 bacterias de los géneros Azotobacter spp y Azospirillum spp, se identificaron las especies A. brasilense, A. lipoferum, A. amazonense y del género Azotobacter las especies A. chroococcum, A. vinelandii, A. paspali y A. beijerinckii. Respecto al inóculo no se encontraron diferencias significativas al realizar su aplicación, se determinó que Azotobacter spp y Azospirillum spp fueron géneros típicos de la flora bacteriana en el cultivo del arroz y en condiciones de campo hubo efecto de los tratamientos en la flora bacteriana, y Azotobacter spp fue el predominante en cada uno de los tratamientos.The study was carried out at the Cauchitos farm, Ibague municipality department of Tolima, with bounds: North 4°23'51" and west 75°9'7", 979 ansm, the average temperature is 24,3°C, tropical dry forest (bs-t in the Holdridge classification. The purpose of this study was to evaluate the association between the nitrogen fixation bacteries with and without inoculo in 10 interespecific rice lines with three nitrogen dosis (0, 50 and 100% de 250 kg/ ha-1 and three repetitions. The inoculation was realized with 10(8 former units of colonies per millimeter. 2.260 bacteries of the generums Azotobacter spp y Azospirrillum spp., and identification the species: Azospirillum brasilense, Azospirillum lipoferum, Azospirillum amazonense, were identified and from the genus Azotobacter were identified the

  10. Aeração e adição de sais na produção de ácido indol acético por bactérias diazotróficas Aeration and salt effects on indol acetic production by diazotrophic bacteria

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    Tharwat El-Sayed El-Desouk Radwan

    2005-10-01

    Full Text Available Foi analisada a produção de compostos indólicos por Azospirillum brasilense Cd, A. lipoferum Br 17, Herbaspirillum seropedicae Z 67, H. rubrisubalbicans M4 e a estirpe 34 isolada de arroz, que não se enquadra em nenhuma das espécies de Herbaspirillum já descritas, em relação a diferentes condições de aeração e concentrações de sais. A maior aeração do meio propiciou aumento na produção de compostos indólicos pelas bactérias testadas. Foi verificado aumento desses compostos, em culturas estáticas, em meio sem nitrogênio no caso de Azospirillum, e na presença de N para as estirpes de Herbaspirillum. O aumento da concentração de sais no meio de cultivo inibiu a produção de compostos indólicos, embora tenha sido observado um pequeno aumento quando a concentração de CaCl2 foi de 1 g L-1. O efeito mais deletério da salinidade foi observado com a presença de NaHCO3, seguido de NaCl e Na2SO4. Azospirillum produziu mais compostos indólicos em meio semi-sólido e Herbaspirillum em meio líquido, mas em menor nível.The production of indolic compounds by Azospirillum brasilense Cd, A. lipoferum Br 17, Herbaspirillum seropedicae Z 67, H. rubrisubalbicans M4, and strain 34 isolated from rice, which does not fit into the described Herbaspirillum species, was measured under aeration ratio and salt concentrations. Aeration of the medium increased growth and production of indole compounds by these bacteria. Under static condition, the production was higher both in nitrogen-free medium for Azospirillum, and in amended N medium for the Herbaspirillum strains. Increasing salt concentration into the medium inhibited the production of indole compounds, although a small increase in production was observed, when CaCl2 concentration was raised above 1 g L-1. Deleterious effect of salinity was more pronounced in the presence of NaHCO3, followed by NaCl and Na2SO4. Azospirillum produced more indolic compounds in semi-solid cultures, and

  11. GERMINATION OF GRASSES DUE TO INOCULATION DIAZOTROPHIC BACTERIA

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    C. D. A. Moreira

    2014-07-01

    Full Text Available The germination of forage grasses suffers from numbness and a natural tendency to low quality. The use of microorganisms inoculated in seeds with the purpose of increasing and meet the demand of some nutrient has been shown to be efficient, but the role of the microorganism in germination and rate of force is still unknown. Therefore the goal as study was to evaluate the germination rate of seeds of three cultivars of Brachiaria brizantha CV. Marandu, b., b. brizantha CV. Xaraés and b. humidícola cv Tupi and a cultivar of millet, P. hybrid cv Massai depending on the bacterium Azospirillum brasilense diazotrofic inoculation (nitrogen-fixing. Germination test was used in seed dispersal to assess the effect of first count (VPC in the treatments with and without inoculation. It was done also conducted further tests of electrical conductivity, weight of thousand seeds and water content. The delineation used was randomized entirely (DIC and the statistical analysis carried out through the analysis of variance and comparison of means using the Tukey test, the 5% probability. Massai grass seeds have the highest rate of force of first count in both treatments. Inoculation of bacterium Azospirillum brasilense did not affect the values of force of first count on seeds of the cultivars Marandu, Xaraés, Tupi and Massai. The seeds of the massai have higher germination speed relative the other cultivars evaluated when inoculated.

  12. A novel interaction between plant-beneficial rhizobacteria and roots: colonization induces corn resistance against the root herbivore Diabrotica speciosa.

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    Franciele Santos

    Full Text Available A number of soil-borne microorganisms, such as mycorrhizal fungi and rhizobacteria, establish mutualistic interactions with plants, which can indirectly affect other organisms. Knowledge of the plant-mediated effects of mutualistic microorganisms is limited to aboveground insects, whereas there is little understanding of what role beneficial soil bacteria may play in plant defense against root herbivory. Here, we establish that colonization by the beneficial rhizobacterium Azospirillum brasilense affects the host selection and performance of the insect Diabrotica speciosa. Root larvae preferentially orient toward the roots of non-inoculated plants versus inoculated roots and gain less weight when feeding on inoculated plants. As inoculation by A. brasilense induces higher emissions of (E-β-caryophyllene compared with non-inoculated plants, it is plausible that the non-preference of D. speciosa for inoculated plants is related to this sesquiterpene, which is well known to mediate belowground insect-plant interactions. To the best of our knowledge, this is the first study showing that a beneficial rhizobacterium inoculant indirectly alters belowground plant-insect interactions. The role of A. brasilense as part of an integrative pest management (IPM program for the protection of corn against the South American corn rootworm, D. speciosa, is considered.

  13. INOCULATION OF DIAZOTROPHIC BACTERIA AND NITROGEN FERTILIZATION IN TOPDRESSING IN IRRIGATED CORN

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    VANESSA ZIRONDI LONGHINI

    2016-01-01

    Full Text Available Corn is a nitrogen-intensive crop, and the use of management practices such as inoculation of the seed with diazotrophic bacteria, which can maximize crop productivity and reduce the need of nitrogen fertilizers, may result in lower production costs. The present study aimed to evaluate the effect of inoculation of corn seed with Azospirillum brasilense and controlled addition of nitrogen to topdressing on the nutrition, production components, and productivity of crop grain. The experimental design was a randomized block design, with four replications in a 2 × 5 factorial scheme. The treatments consisted of inoculation or not of corn seed with A. brasilense (at 100 mL per 25 kg of seed and five nitrogen (N levels in topdressing (0, 30, 60, 90, and 120 kg N ha-1 from urea [45% N] were applied when the corn was in the phenological growth stage V6. Foliar macronutrients, foliar chlorophyll index (FCI, production components, and yield of corn grain were valuated. Inoculation of corn seeds with A. brasilense increased plant height and grain yield. Fertilization in topdressing, with N levels up to 120 kg ha-1, linearly increased the foliar nutrients and productivity of corn cultivated in the spring/summer in the low-altitude Cerrado region of Brazil.

  14. The use of bacteria for detecting toxic effects of pollutants in soil and water

    Science.gov (United States)

    Obiakor, Maximilian; Wilson, Susan; Tighe, Matthew; Pereg, Lily

    2017-04-01

    Microbial abundance and diversity are essential for sustaining soil structure and function and have been strongly linked to human health and wellbeing. Antimony (Sb) in the environment can present an ecological hazard and depending on concentration can be lethal. The toxic effects of Sb(III) and Sb(V) on the model soil bacterium Azospirillum brasilense Sp7 were assessed in exposure-dose-response assays and water samples from an Sb contaminated creek were analyzed for bacterial mortality. In both cases, Sb(III) and Sb(V) greatly affected the survival of A. brasilense Sp7 cells. The Sb(III) had a greater toxic effect than Sb(V) at all concentrations tested. Critical concentrations of Sb also caused variant colonies to appear, indicating both acute and sub-lethal effects, which were dose and time dependent. This work demonstrates the usefulness of A. brasilense as an indicator species to detect harmful effects of an environmental pollutant of emerging concern.

  15. A novel interaction between plant-beneficial rhizobacteria and roots: colonization induces corn resistance against the root herbivore Diabrotica speciosa.

    Science.gov (United States)

    Santos, Franciele; Peñaflor, Maria Fernanda G V; Paré, Paul W; Sanches, Patrícia A; Kamiya, Aline C; Tonelli, Mateus; Nardi, Cristiane; Bento, José Mauricio S

    2014-01-01

    A number of soil-borne microorganisms, such as mycorrhizal fungi and rhizobacteria, establish mutualistic interactions with plants, which can indirectly affect other organisms. Knowledge of the plant-mediated effects of mutualistic microorganisms is limited to aboveground insects, whereas there is little understanding of what role beneficial soil bacteria may play in plant defense against root herbivory. Here, we establish that colonization by the beneficial rhizobacterium Azospirillum brasilense affects the host selection and performance of the insect Diabrotica speciosa. Root larvae preferentially orient toward the roots of non-inoculated plants versus inoculated roots and gain less weight when feeding on inoculated plants. As inoculation by A. brasilense induces higher emissions of (E)-β-caryophyllene compared with non-inoculated plants, it is plausible that the non-preference of D. speciosa for inoculated plants is related to this sesquiterpene, which is well known to mediate belowground insect-plant interactions. To the best of our knowledge, this is the first study showing that a beneficial rhizobacterium inoculant indirectly alters belowground plant-insect interactions. The role of A. brasilense as part of an integrative pest management (IPM) program for the protection of corn against the South American corn rootworm, D. speciosa, is considered.

  16. Nitrogen fixed by wheat plants as affected by nitrogen fertilizer levels and Non-symbiotic bacteria

    International Nuclear Information System (INIS)

    Soliman, S.; Aly, S.S.M.; Gadalla, A.M.; Abou Seeda, M.

    1995-01-01

    Inorganic nitrogen is required for all egyptian soils for wheat. Free living and N 2-fixing microorganisms are able associate closely related with the roots of geraminacae. Pot experiment studies were carried out to examine the response of wheat plants to inoculation with Azospirillum Brasilense and Azotobacter Chroococcum, single or in combination, under various levels of ammonium sulfate interaction between both the inoculants increased straw or grain yield as well as N-uptake by wheat plants with increasing N levels. Results showed that grains of wheat plants derived over 19,24 and 15% of its N content from the atmospheric - N 2 (Ndfa) with application of 25,50 and 75 mg N kg-1 soil in the presence of + Azospirillum + azotobacter. The final amount of N 2-fixers. The highest values of N 2-fixed were observed with mixed inoculants followed by inoculation with Azospirillum and then azotobacter. The recovery of applied ammonium sulfate-N was markedly increased by inoculation with combined inoculants, but less in uninoculated treatments. Seeds inoculated with non-symbiotic fixing bacteria could be saved about 25 kg N without much affecting the grain yield. i fig., 4 tabs

  17. Nitrogen fixed by wheat plants as affected by nitrogen fertilizer levels and Non-symbiotic bacteria

    Energy Technology Data Exchange (ETDEWEB)

    Soliman, S; Aly, S S.M.; Gadalla, A M [Soils and Water Dept., Atomic Energy Authority, Cairo (Egypt); Abou Seeda, M [Soils and Water Dept., National Res. Centre, Cairo (Egypt)

    1995-10-01

    Inorganic nitrogen is required for all egyptian soils for wheat. Free living and N 2-fixing microorganisms are able associate closely related with the roots of geraminacae. Pot experiment studies were carried out to examine the response of wheat plants to inoculation with Azospirillum Brasilense and Azotobacter Chroococcum, single or in combination, under various levels of ammonium sulfate interaction between both the inoculants increased straw or grain yield as well as N-uptake by wheat plants with increasing N levels. Results showed that grains of wheat plants derived over 19,24 and 15% of its N content from the atmospheric - N 2 (Ndfa) with application of 25,50 and 75 mg N kg-1 soil in the presence of + Azospirillum + azotobacter. The final amount of N 2-fixers. The highest values of N 2-fixed were observed with mixed inoculants followed by inoculation with Azospirillum and then azotobacter. The recovery of applied ammonium sulfate-N was markedly increased by inoculation with combined inoculants, but less in uninoculated treatments. Seeds inoculated with non-symbiotic fixing bacteria could be saved about 25 kg N without much affecting the grain yield. i fig., 4 tabs.

  18. Characterization of diazotrophic bacteria non-symbiotic associated with eucalyptus (eucalyptus sp.) in Codazzi, Cesar (Colombia)

    International Nuclear Information System (INIS)

    Obando Castellanos, Dolly Melissa; Burgos Zabala, Ludy Beatriz; Rivera Botia, Diego Mauricio; Rubiano Garrido, Maria Fernanda; Divan Baldini, Vera Lucia; Bonilla Buitrago, Ruth Rebeca

    2010-01-01

    The effect of climatic seasons (rainy and dry) and the stratum sample (rhizospheric soil, roots and leaves) the population of the genera Azotobacter, Beijerinckia, Derxia, Azospirillum, Herbaspirillum, Gluconacetobacter and Burkholderia in soil rhizosphere, roots and leaves of eucalyptus (eucalyptus sp.). It also assesses their ability to produce indoles compounds as plant growth promoters and their acetylene reduction activity as an indicator of biological fixation of nitrogen. The results showed no statistically significant differences in the Duncan test (p ≤ 0.05) in the population with respect to the climate epoch, suggesting that these bacteria are able to tolerate stress conditions by different physiological mechanisms. With respect to the stratum sample isolates attempts of Herbaspirillum sp. and Azospirillum sp. significant differences in rhizospheric soil and roots. we obtained 44 isolates of which were grouped by phenotypic characterization as 14 suspected of Beijerinckia sp., 12 Azotobacter sp., 8 Derxia sp., 4 Herbaspirillum sp., 5 Azospirillum sp., 1 Gluconacetobacter sp. and 1 Burkholderia sp. due to their high potential were selected isolates C27, C26 and C25. These four strains present the best values of efficiency in vitro, exceeding production values of the reference strains used (A. chroococcum (AC1) and a. brasilense (SP7)).

  19. HONGO ENDOMICORRÍZICO Y BACTERIA FIJADORA DE NITRÓGENO INOCULADAS A Coffea arabica EN VIVERO

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    Juan Francisco Aguirre-Medina

    2011-01-01

    Full Text Available Con el objetivo de determinar el efecto de la inoculación con Azospirillum brasilense y Glomus intraradice en café, se estableció la presente investigación en un vivero en el Campo Experimental Rosario Izapa, Chiapas, México de septiembre de 2005 a abril de 2006. Se utilizó un suelo Andosol¿mólico típico de la región cafetalera del Soconusco Chiapas, México. El A. brasilense tuvo una concentración de 100 x 106 bacterias por gramo de turba y el hongo micorrízico, cuarenta esporas por gramo de suelo con infección de 95% en el sistema radical de cebolla. Los tratamientos utilizados fueron los microorganismos solos, la combinación de ambos y el testigo sin inocular que se distribuyeron en un diseño de bloques completos al azar. Se evaluaron variables morfológicas y fisiológicas del rendimiento cada treinta días a partir del segundo mes de siembra durante siete meses y se determinó el contenido de N, P y Ca en el tejido vegetal. Los resultados se analizaron estadísticamente y las diferencias entre tratamientos se compararon de acuerdo a Tukey 5%. Los resultados indican una respuesta diferencial entre los microorganismos. A. brasilense indujo mayor desarrollo radical y la simbiosis doble G. intraradices + A. brasilense mejoró el desarrollo del tallo y lámina foliar. El contenido de N, P y Ca se presentó de forma consistente con G. intraradices.

  20. Identification and characterization of trans-3-hydroxy-l-proline dehydratase and Δ1-pyrroline-2-carboxylate reductase involved in trans-3-hydroxy-l-proline metabolism of bacteria

    Directory of Open Access Journals (Sweden)

    Seiya Watanabe

    2014-01-01

    Full Text Available trans-4-Hydroxy-l-proline (T4LHyp and trans-3-hydroxy-l-proline (T3LHyp occur mainly in collagen. A few bacteria can convert T4LHyp to α-ketoglutarate, and we previously revealed a hypothetical pathway consisting of four enzymes at the molecular level (J Biol Chem (2007 282, 6685–6695; J Biol Chem (2012 287, 32674–32688. Here, we first found that Azospirillum brasilense has the ability to grow not only on T4LHyp but also T3LHyp as a sole carbon source. In A. brasilense cells, T3LHyp dehydratase and NAD(PH-dependent Δ1-pyrroline-2-carboxylate (Pyr2C reductase activities were induced by T3LHyp (and d-proline and d-lysine but not T4LHyp, and no effect of T3LHyp was observed on the expression of T4LHyp metabolizing enzymes: a hypothetical pathway of T3LHyp → Pyr2C → l-proline was proposed. Bacterial T3LHyp dehydratase, encoded to LhpH gene, was homologous with the mammalian enzyme. On the other hand, Pyr2C reductase encoded to LhpI gene was a novel member of ornithine cyclodeaminase/μ-crystallin superfamily, differing from known bacterial protein. Furthermore, the LhpI enzymes of A. brasilense and another bacterium showed several different properties, including substrate and coenzyme specificities. T3LHyp was converted to proline by the purified LhpH and LhpI proteins. Furthermore, disruption of LhpI gene from A. brasilense led to loss of growth on T3LHyp, d-proline and d-lysine, indicating that this gene has dual metabolic functions as a reductase for Pyr2C and Δ1-piperidine-2-carboxylate in these pathways, and that the T3LHyp pathway is not linked to T4LHyp and l-proline metabolism.

  1. Molecular characterization of nitrogen-fixing bacteria isolated from brazilian agricultural plants at São Paulo state Caracterização molecular de bactérias fixadoras de nitrogênio isoladas de plantas brasileiras no estado de São Paulo

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    Érica. L. Reinhardt

    2008-09-01

    Full Text Available Fourteen strains of nitrogen-fixing bacteria were isolated from different agricultural plant species, including cassava, maize and sugarcane, using nitrogen-deprived selective isolation conditions. Ability to fix nitrogen was verified by the acetylene reduction assay. All potentially nitrogen-fixing strains tested showed positive hybridization signals with a nifH probe derived from Azospirillum brasilense. The strains were characterized by RAPD, ARDRA and 16S rDNA sequence analysis. RAPD analyses revealed 8 unique genotypes, the remaining 6 strains clustered into 3 RAPD groups, suggesting a clonal origin. ARDRA and 16S rDNA sequence analyses allowed the assignment of 13 strains to known groups of nitrogen-fixing bacteria, including organisms from the genera Azospirillum, Herbaspirillum, Pseudomonas and Enterobacteriaceae. Two strains were classified as Stenotrophomonas ssp. Molecular identification results from 16S rDNA analyses were also corroborated by morphological and biochemical data.Quatorze linhagens de bactérias fixadoras de nitrogênio foram isoladas de diferentes espécies de plantas, incluindo cassava, milho e cana-de-açúcar, usando condições seletivas desprovidas de nitrogênio. A capacidade de fixar nitrogênio foi verificada por ensaio de redução de acetileno. Todas as linhagens fixadoras de nitrogênio testadas apresentaram hibridização positiva com sonda de gene nifH derivada de Azospirillum brasilense. As linhagens foram caracterizadas por RAPD, ARDRA e sequenciamento do gene 16S rDNA. As análises de RAPD revelaram 8 genótipos, as 6 linhagens restantes foram agrupadas em 3 grupos de RAPD, sugerindo uma origem clonal. ARDRA e seqüências de 16S rDNA foram alocadas em 13 grupos conhecidos de bactérias fixadoras de nitrogênio, incluindo organismos dos gêneros Azospirillum, Herbaspirillum, Pseudomonas e Enterobacteriaceae. Duas linhagens foram classificadas como Stenotrophomonas ssp. Os resultados da identifica

  2. SOILS, FERTILIZATION AND MANAGEMENT OF WATER Halotolerant/alkalophilic bacteria associated with the cyanobacterium Arthrospira platensis (Nordstedt Gomont that promote early growth in Sorghum bicolor (L. Moench

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    Liliana Gómez G

    2012-01-01

    Full Text Available Arthrospira platensis associated bacteria (APAB identified through molecuar biology like Bacillus okhensis, Indibacter alkaliphilus and Halomonas sp., are also producing 3-indol acetic acid (IAA, these bacteria was used in early plant growth promotion tests over Sorghum bicolor, these bioassay was considered indirect evidence to suggest that APAB also may have stimulatory effects over A. platensis growth naturally. I. alkaliphilus and B. okhensis enhanced early germination of S. bicolor seads, with better results than that achieved by Azospirillum brasilense, bacterium used like reference as a common plant growth promoting rizobacteria. The three APAB enhanced significative differences (P≤0.05 over morphoagronomic parameters, I. alkaliphilus and B. okhensis exhibith better resoults in elongation stimulation and root and foliage dry weight. Above evidence suggest this bacteria like plant growth promoting and it recomended testing with A. platensis axenic cultures and its associated bactteri for understanding true interaction between them.

  3. Efecto de diferentes concentraciones de ácido antranílico en el crecimiento del maíz

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    José Luis Hernández-Mendoza

    2010-01-01

    Full Text Available La rizobacteria Azospirillum brasilense basa su capacidad promotora del crecimiento vegetal en la producción de auxinas y otras hormonas, entre ellas el ácido antranílico (AA. En este trabajo se determinó el efecto del AA (0, 500, 1000, 3000 y 5000 ppm en el crecimiento y la acumulación de biomasa del híbrido de maíz 83G66 en condiciones de invernadero. El AA de 500 a 3000 ppm promovió un mayor crecimiento (área foliar y altura de planta, y el AA de 1000 y 3000 ppm incrementó significativamente la biomasa seca en maíz en comparación con el testigo. El 90% de la asimilación del AA en las plantas ocurrió durante los primeros 10 días después del tratamiento.

  4. Ocorrência e diversidade de bactérias diazotróficas associadas a gramíneas forrageiras do Pantanal Sul Matogrossense Occurrence and diversity of diazotrophic bacteria associated to forage grasses of the Pantanal in the state of Mato Grosso do Sul

    Directory of Open Access Journals (Sweden)

    Marivaine da Silva Brasil

    2005-04-01

    Full Text Available Este trabalho teve por objetivo avaliar a ocorrência e a diversidade genética de bactérias fixadoras de N2 associadas às gramíneas nativas Elyonurus muticus (capim carona e Axonopus purpusii (capim mimoso e à gramínea exótica Brachiaria humidicola (braquiária que formam as pastagens na região da Nhecolândia. As coletas das plantas e solo foram feitas nos períodos de seca e de cheia para determinar a população de bactérias diazotróficas. Identificaram-se Azospirillum brasilense, A. lipoferum, A. amazonense, Herbaspirillum spp., Burkholderia spp. em amostras de solo, raízes e folhas das três espécies forrageiras. As populações dessas bactérias foram menores na época da cheia em comparação com a época da seca. A diversidade genética das bactérias isoladas foi avaliada por meio da técnica de análise de restrição do DNA ribossomal amplificado (ARDRA. Os isolados foram divididos em cinco grupos genotípicos distintos. Os isolados de A. brasilense e A. lipoferum apresentaram cerca de 50 % de similaridade, enquanto A. amazonense formou um grupo a parte, com apenas 25 % de similaridade em relação ao grupo das espécies do gênero. As bactérias do gênero Herbaspirillum formaram um grupo isolado com apenas 25 % de similaridade em relação ao gênero Azospirillum. O quinto grupo foi formado por apenas um isolado com 25 % de similaridade em relação aos demais.This study was carried out to verify the occurrence and genetic diversity of diazotrophic bacteria associated to the native graminaceus plants Elyonurus muticus (Carona grass and Axonopus purpusii (Mimoso grass and the exotic Brachiaria humidicola (Brachiaria that form the pastures in the Nhecolândia region of the Pantanal in the state of Mato Grosso do Sul, Brazil. The plants were harvested in the dry and rainy seasons and the diazotrophic bacteria populations in the soil and on roots and leaves of the three grasses were determined. Strains belonging to the

  5. A simple and efficient method for poly-3-hydroxybutyrate quantification in diazotrophic bacteria within 5 minutes using flow cytometry

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    L.P.S. Alves

    Full Text Available The conventional method for quantification of polyhydroxyalkanoates based on whole-cell methanolysis and gas chromatography (GC is laborious and time-consuming. In this work, a method based on flow cytometry of Nile red stained bacterial cells was established to quantify poly-3-hydroxybutyrate (PHB production by the diazotrophic and plant-associated bacteria, Herbaspirillum seropedicae and Azospirillum brasilense. The method consists of three steps: i cell permeabilization, ii Nile red staining, and iii analysis by flow cytometry. The method was optimized step-by-step and can be carried out in less than 5 min. The final results indicated a high correlation coefficient (R2=0.99 compared to a standard method based on methanolysis and GC. This method was successfully applied to the quantification of PHB in epiphytic bacteria isolated from rice roots.

  6. A simple and efficient method for poly-3-hydroxybutyrate quantification in diazotrophic bacteria within 5 minutes using flow cytometry.

    Science.gov (United States)

    Alves, L P S; Almeida, A T; Cruz, L M; Pedrosa, F O; de Souza, E M; Chubatsu, L S; Müller-Santos, M; Valdameri, G

    2017-01-16

    The conventional method for quantification of polyhydroxyalkanoates based on whole-cell methanolysis and gas chromatography (GC) is laborious and time-consuming. In this work, a method based on flow cytometry of Nile red stained bacterial cells was established to quantify poly-3-hydroxybutyrate (PHB) production by the diazotrophic and plant-associated bacteria, Herbaspirillum seropedicae and Azospirillum brasilense. The method consists of three steps: i) cell permeabilization, ii) Nile red staining, and iii) analysis by flow cytometry. The method was optimized step-by-step and can be carried out in less than 5 min. The final results indicated a high correlation coefficient (R2=0.99) compared to a standard method based on methanolysis and GC. This method was successfully applied to the quantification of PHB in epiphytic bacteria isolated from rice roots.

  7. A simple and efficient method for poly-3-hydroxybutyrate quantification in diazotrophic bacteria within 5 minutes using flow cytometry

    Science.gov (United States)

    Alves, L.P.S.; Almeida, A.T.; Cruz, L.M.; Pedrosa, F.O.; de Souza, E.M.; Chubatsu, L.S.; Müller-Santos, M.; Valdameri, G.

    2017-01-01

    The conventional method for quantification of polyhydroxyalkanoates based on whole-cell methanolysis and gas chromatography (GC) is laborious and time-consuming. In this work, a method based on flow cytometry of Nile red stained bacterial cells was established to quantify poly-3-hydroxybutyrate (PHB) production by the diazotrophic and plant-associated bacteria, Herbaspirillum seropedicae and Azospirillum brasilense. The method consists of three steps: i) cell permeabilization, ii) Nile red staining, and iii) analysis by flow cytometry. The method was optimized step-by-step and can be carried out in less than 5 min. The final results indicated a high correlation coefficient (R2=0.99) compared to a standard method based on methanolysis and GC. This method was successfully applied to the quantification of PHB in epiphytic bacteria isolated from rice roots. PMID:28099582

  8. Quantification of root associated nitrogen fixation in kallar grass as estimated by sup/15/nitrogen isotope dilution

    International Nuclear Information System (INIS)

    Malik, K.A.; Zafar, Y.

    1985-01-01

    Present investigations were made by using sup/15/N isotope dilution technique to quantitatively estimate BNF in Kallar grass when grown under controlled conditions in nutrient solution and inoculated with N sub/2/-fixing bacteria. Azospirillum brasilense and two isolates from the rhizosphere of kallar grass were used as inoculant. After harvest acetylen reduction of roots, total yield, total N and sup/15/ N analysis were made. Total-N in inoculated treatments was 2-3 times higher than in control and so were the fresh and dry weight yields. The estimates based on isotopic dilution indicated that 50-70 percent N in the plant was derived from BNF in case of inoculated treatment. The results based on N balance gave relatively lower values of 40-60 percent of total N derived from fixation. The data revealed that in Kallar grass a substantial amount of plant N is derived from BNF. (orig./A.B.)

  9. Effect of cover crops and nitrogen rates on sprinkler irrigated wheat in low altitude cerrado

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    Michelle Traete Sabundjian

    2016-06-01

    Full Text Available RESUMO A produção de trigo no cerrado brasileiro enfrenta grandes desafios, principalmente por não ser a região tradicionalmente tritícola e pela ocorrência de inverno quente e seco. Assim, o objetivo deste trabalho foi avaliar o efeito residual das culturas antecessoras, milho e Urochloa ruziziensis (R. Germ & Evrard, em cultivo exclusivo e em consórcio entre ambas, na presença e ausência da inoculação de sementes com Azospirillum brasilense e adubação nitrogenada (N em cobertura, no desenvolvimento e na produtividade do trigo. O experimento foi desenvolvido em Selvíria, MS, em 2011/12. O delineamento experimental foi o de blocos ao acaso, disposto em esquema fatorial 8x4, com quatro repetições, cujos tratamentos foram constituídos pela combinação de restos culturais (associações de milho, Urochloa ruziziensis e Azospirillum brasilense e doses de N (0, 30, 60 e 90 kg ha-1 em cobertura, no trigo. Realizaram-se as seguintes avaliações: cobertura vegetal residual (quantidade, características agronômicas, componentes de produção e produtividade da cultura do trigo. As culturas antecessoras apresentaram efeitos positivos na produtividade do trigo cultivado em sucessão, sendo o consórcio de milho e Urochloa ruziziensis, com ou sem inoculação excelente opção de manejo; o incremento da dose de N, em cobertura, até 90 kg ha- 1 aumenta a produtividade de grãos de trigo irrigado, dependendo da cultura antecessora.

  10. Swimming motility plays a key role in the stochastic dynamics of cell clumping

    International Nuclear Information System (INIS)

    Qi, Xianghong; Nellas, Ricky B; Byrn, Matthew W; Russell, Matthew H; Bible, Amber N; Alexandre, Gladys; Shen, Tongye

    2013-01-01

    Dynamic cell-to-cell interactions are a prerequisite to many biological processes, including development and biofilm formation. Flagellum induced motility has been shown to modulate the initial cell–cell or cell–surface interaction and to contribute to the emergence of macroscopic patterns. While the role of swimming motility in surface colonization has been analyzed in some detail, a quantitative physical analysis of transient interactions between motile cells is lacking. We examined the Brownian dynamics of swimming cells in a crowded environment using a model of motorized adhesive tandem particles. Focusing on the motility and geometry of an exemplary motile bacterium Azospirillum brasilense, which is capable of transient cell–cell association (clumping), we constructed a physical model with proper parameters for the computer simulation of the clumping dynamics. By modulating mechanical interaction (‘stickiness’) between cells and swimming speed, we investigated how equilibrium and active features affect the clumping dynamics. We found that the modulation of active motion is required for the initial aggregation of cells to occur at a realistic time scale. Slowing down the rotation of flagellar motors (and thus swimming speeds) is correlated to the degree of clumping, which is consistent with the experimental results obtained for A. brasilense. (paper)

  11. Swimming motility plays a key role in the stochastic dynamics of cell clumping

    Science.gov (United States)

    Qi, Xianghong; Nellas, Ricky B.; Byrn, Matthew W.; Russell, Matthew H.; Bible, Amber N.; Alexandre, Gladys; Shen, Tongye

    2013-04-01

    Dynamic cell-to-cell interactions are a prerequisite to many biological processes, including development and biofilm formation. Flagellum induced motility has been shown to modulate the initial cell-cell or cell-surface interaction and to contribute to the emergence of macroscopic patterns. While the role of swimming motility in surface colonization has been analyzed in some detail, a quantitative physical analysis of transient interactions between motile cells is lacking. We examined the Brownian dynamics of swimming cells in a crowded environment using a model of motorized adhesive tandem particles. Focusing on the motility and geometry of an exemplary motile bacterium Azospirillum brasilense, which is capable of transient cell-cell association (clumping), we constructed a physical model with proper parameters for the computer simulation of the clumping dynamics. By modulating mechanical interaction (‘stickiness’) between cells and swimming speed, we investigated how equilibrium and active features affect the clumping dynamics. We found that the modulation of active motion is required for the initial aggregation of cells to occur at a realistic time scale. Slowing down the rotation of flagellar motors (and thus swimming speeds) is correlated to the degree of clumping, which is consistent with the experimental results obtained for A. brasilense.

  12. Construction of expression vector containing glnA gene and detection of NPT II activity in the transgenic rice calli using 32P-labelled compound

    International Nuclear Information System (INIS)

    Su Jin; Zhang Xueqin; Yan Qiusheng; Chen Zhangliang; You Chongbiao

    1993-08-01

    The glnA gene encoding glutamine synthetase (GS) was amplified from Azospirillum brasilense Sp7 by PCR technique. the amplified 1.4 kb DNA fragment was cloned at the EcoRV site of Bluescript-SK. Both sequencing and restriction digestion data showed that the 1.4 kb DNA fragment flanked with BamHI site at each end was really the glnA gene of A. brasilense Sp7. The glnA gene was ligated with Bg1 II site of pCo24. As a result, an expression vector pGSC35 with CaMV35S promoter was obtained. Using colony in situ hybridization with α- 32 P-dATP labelled probes to screen the positive clones, another glnA gene expression vector pAGNB92 with rice actin 1 promoter was constructed after three rounds of ligation and transformation. Protoplasts isolated from rice cell suspension line cv. T986 were transformed with glnA expression vectors pGSC35 and pAGNB92 containing neomycin phosphotransferase II (NPTII) gene by using PEG fusion and electroporation. Transformed microcalli were selected on media containing G418 disulfate salt. NPT II activity was detected in 37% of G418 resistant calli by using dot blot hybridization with γ- 32 P-ATP and kanamycin as substrate

  13. Methodological effects in Fourier transform infrared (FTIR) spectroscopy: Implications for structural analyses of biomacromolecular samples

    Science.gov (United States)

    Kamnev, Alexander A.; Tugarova, Anna V.; Dyatlova, Yulia A.; Tarantilis, Petros A.; Grigoryeva, Olga P.; Fainleib, Alexander M.; De Luca, Stefania

    2018-03-01

    A set of experimental data obtained by Fourier transform infrared (FTIR) spectroscopy (involving the use of samples ground and pressed with KBr, i.e. in a polar halide matrix) and by matrix-free transmission FTIR or diffuse reflectance infrared Fourier transform (DRIFT) spectroscopic methodologies (involving measurements of thin films or pure powdered samples, respectively) were compared for several different biomacromolecular substances. The samples under study included poly-3-hydroxybutyrate (PHB) isolated from cell biomass of the rhizobacterium Azospirillum brasilense; dry PHB-containing A. brasilense biomass; pectin (natural carboxylated heteropolysaccharide of plant origin; obtained from apple peel) as well as its chemically modified derivatives obtained by partial esterification of its galacturonide-chain hydroxyl moieties with palmitic, oleic and linoleic acids. Significant shifts of some FTIR vibrational bands related to polar functional groups of all the biomacromolecules under study, induced by the halide matrix used for preparing the samples for spectroscopic measurements, were shown and discussed. A polar halide matrix used for preparing samples for FTIR measurements was shown to be likely to affect band positions not only per se, by affecting band energies or via ion exchange (e.g., with carboxylate moieties), but also by inducing crystallisation of metastable amorphous biopolymers (e.g., PHB of microbial origin). The results obtained have important implications for correct structural analyses of polar, H-bonded and/or amphiphilic biomacromolecular systems using different methodologies of FTIR spectroscopy.

  14. Associative bacteria influence maize (Zea mays L.) growth, physiology and root anatomy under different nitrogen levels.

    Science.gov (United States)

    Calzavara, Anderson Kikuchi; Paiva, Pedro Henrique Godoy; Gabriel, Lorrant Cavanha; de Oliveira, André Luiz Martinez; Milani, Karina; Oliveira, Halley Caixeta; Bianchini, Edmilson; Pimenta, José Antonio; de Oliveira, Maria Cristina Neves; Dias-Pereira, Jaqueline; Stolf-Moreira, Renata

    2018-05-15

    Despite the great diversity of plant growth-promoting bacteria (PGPB) with potential to partially replace the use of N-fertilizers in agriculture, few PGPB are explored for the production of commercial inoculants, reinforcing the importance of identifying positive plant-bacteria interactions. Aiming to better understand the influence of PGPB inoculation in plant development, two PGPB species with distant phylogenetic relationship were inoculated in maize. Maize seeds were inoculated with Bacillus sp. or Azospirillum brasilense. After germinating, the plants were subjected to two nitrogen treatments: full (N+) and limiting (N-) nitrogen supply. Then, anatomical, biometric and physiological analyses were performed. Both PGPB species modified the anatomical pattern of roots, as verified by the higher metaxylem vessel elements (MVE) number. Bacillus sp. also increased the MVE area in maize roots. Under N+ condition, both PGPB decreased the leaf protein content and led to the development of shorter roots; however, Bacillus sp. increased root and shoot dry weight, whereas A. brasilense increased photosynthesis rate and leaf nitrate content. In plants subjected to N limitation (N-), photosynthesis rate and photosystem II efficiency increased in those inoculated with Bacillus sp., whilst A. brasilense led to higher ammonium, amino acids and total soluble sugars contents in the leaves, compared to control. Plant developmental and metabolical patterns were switched by the inoculation, regardless the inoculant bacteria used, producing similar as well as distinct modifications on the parameters studied. These results indicatie that even non-diazotrophic inoculant strains can improve the plant N-status as result of the morpho-anatomical and physiological modifications produced by the PGPB. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

  15. Plant growth-promoting bacteria associated with nitrogen fertilization at topdressing in popcorn agronomic performance

    Directory of Open Access Journals (Sweden)

    Leandro Teodoski Spolaor

    2016-03-01

    Full Text Available ABSTRACT The use of plant growth-promoting bacteria is a promising alternative with low environmental impact to increase the efficiency of use of chemical fertilizers, ensuring high yield with better cost-effective ratio. In maize crops, several studies have demonstrated an increased yield when Azospirillum-based inoculants are used. In the case of popcorn, there are no available studies related to use of inoculation and its response on yield parameters. Thus, the aim of this study was to evaluate the field performance of popcorn when inoculated with the commercial product Masterfix L (A. brasilense Ab-V5 and A. brasilense Ab-V6 and the non-commercial inoculant UEL (A. brasilense Ab-V5 + Rhizobium sp. 53GRM1 associated with nitrogen fertilization. The trials were conducted in Londrina and Maringá, Paraná State, Brazil, in a randomized block design with four replications, in a split plot design with the inoculation treatments located in the plots (uninoculated, Masterfix L, and UEL and the different N rates located in the subplots where ammonium sulphate was applied in the topdressing at the V6 stage (0, 50, 100, and 150 kg∙ha–1. The variance analysis showed significant effects (p < 0.05 of inoculation (Londrina environment and N rates (both environments only for grain yield. There was no inoculation effect in the grain yield when inoculants were applied together with N-fertilization at topdressing. In the absence of N-fertilization at topdressing, the inoculants Masterfix L. and UEL promoted higher grain yield as compared to the uninoculated plants, with resulting increases of 13.21 and 26.61% in yield, respectively.

  16. Evaluación de la asociación bacterias fijadoras de nitrógeno - líneas interespecíficas de arroz-nitrógeno, en Typic haplustalf. Ibagué, Colombia

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    Margarita M Vallejo

    2008-01-01

    Full Text Available El estudio se llevó a cabo en la hacienda Cauchitos, municipio de Ibagué, departamento del Tolima (Norte 4° 23' 51" y Oeste 75° 9' 7", 979 msnm, 24.3°C, bosque seco tropical (bs-T, con el objetivo de evaluar las asociaciones entre bacterias fijadoras de nitrógeno con inóculo y sin él en diez líneas interespecíficas de arroz, con tres dosis de nitrógeno (0%, 50% y 100% de 250 kg/ha-1 y tres repeticiones por tratamiento. La inoculación se realizó con 1 cm³ de unidades formadoras de colonias por 250 g de semilla de cada cultivar. Se aislaron 2.260 bacterias de los géneros Azotobacter spp y Azospirillum spp, se identificaron las especies A. brasilense, A. lipoferum, A. amazonense y del género Azotobacter las especies A. chroococcum, A. vinelandii, A. paspali y A. beijerinckii. Respecto al inóculo no se encontraron diferencias significativas al realizar su aplicación, se determinó que Azotobacter spp y Azospirillum spp fueron géneros típicos de la flora bacteriana en el cultivo del arroz y en condiciones de campo hubo efecto de los tratamientos en la flora bacteriana, y Azotobacter spp fue el predominante en cada uno de los tratamientos.

  17. Co-inoculation with diazotrophic bacteria in soybeans associated to urea topdressing

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    Glauber Monçon Fipke

    Full Text Available ABSTRACT Increased grain yield can be obtained via an interaction between plants and growth-promoting microorganisms. The Bradyrhizobium spp. are capable of fixing atmospheric nitrogen in soybeans [Glycine max (L. Merril], and Azospirillum spp. induce the synthesis of phytohormones. The aim of this study was to evaluate inoculation with Bradyrhizobium and co-inoculation with Bradyrhizobium + Azospirillum brasilense in soybeans in combination with the application a topdressing of 0, 75 or 150 kg of N ha-1 of urea during the reproductive stage. Three soybean cultivars (BMX Ativa, TEC 6029 and BMX Potência, were tested in field experiments in Santa Maria, RS, Brazil, during two agricultural years (2013/2014 and 2014/2015 and two sowing times. Morphological, nodulation and yield components were evaluated. Co-inoculation increased the grain yield by 240 kg ha-1 compared with conventional inoculation. When co-inoculated, cultivars BMX Ativa, TEC 6029 and BMX Potência showed increased grain yields of 6, 4 and 12%, respectively. The application of 150 kg ha-1 of N as a topdressing increased the grain yield by 300 kg ha-1 in the co-inoculated cultivars TEC 6029 and BMX Potência, but without a financial return. When inoculated only with Bradyrhizobium, the cultivars did not respond positively to the application of urea.

  18. Study of Beneficial Levels and Effect of Azotobacter spp. and Azospirillium spp.

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    A Ostadi Jaafari

    2012-10-01

    Full Text Available In order to evaluate the effects of beneficial free living bacteria (Azotobacter chroococcum and Azospirillum brasilense compared to different nitrogen fertilizer levels on yield and yield components of barley (Hordeum vulgare cv Reyhan a field experiment was conducted at Research Station College of Agriculture, Ferdowsi University of Mashhad in 2007-2008. The experiment was arranged in a randomized complete block design with three replications. Fertilizer treatments were biological fertilizer (combine of Azotobacter and Azospirillum and six nitrogen fertilizer levels (0, 20, 40, 60, 80 and 100 kg/ha. The plant characteristics were studied in terms of leaf area index, crop growth rate, total dry weight, shoot and root dry matter per plant and seed yield. The results showed that the effect of different nitrogen fertilizer levels imposed a significant effect on all plant characteristics. The difference between biological fertilizers, 60 and 80kg nitrogen fertilizer levels in shoot dry weight were not significant. Additionally, in root dry weight and root/shoot ratio there were significant difference between biological fertilizer and all nitrogen fertilizer levels. There was no significant difference between biological fertilizer, 80 and 100 kg nitrogen fertilizer levels in terms of seed yield. There was no significant difference among biological fertilizer, 40, 60 and 80kg nitrogen fertilizer levels in leaf area index at three finally samples. It seems that, in this experiment biological fertilizer could be provide plant nitrogen requirements the same as 40-80kg nitrogen per hectare.

  19. Increased root exudation of /sup 14/C-compounds by sorghum seedlings inoculated with nitrogen-fixing bacteria

    Energy Technology Data Exchange (ETDEWEB)

    Lee, K.J. (Institute of Forest Genetics, Suweon (Republic of Korea)); Gaskins, M.H. (Florida Univ., Gainesville (USA). Dept. of Agriculture)

    1982-01-01

    Organic components leaked from Sorghum bicolor seedlings ('root exudates') were examined by recovering /sup 14/C labelled compounds from root solutions of seedlings inoculated with Azospirillum brasilense, Azotobacter vinelandii or Klebsiella pneumoniae nif-. Up to 3.5% of the total /sup 14/C recovered from shoots, roots, and nutrient solutions was found in the root solutions. Inoculation with Azospirillum and Azotobacter increased the amounts of /sup 14/C and decreased the amounts of carbohydrates in the root solutions. When sucrose was added as a carbon source for the bacteria, the increase of /sup 14/C in the solutions did not occur. Quantities of /sup 14/C found in the root solutions were proportional to amounts of mineral nitrogen supplied to the plants. Bacterial growth also was proportional to nitrogen levels. When sorghum plants were grown in soil and labelled with /sup 14/CO/sub 2/, about 15% of the total /sup 14/C recovered within 48 hours exposure was found in soil leachates.

  20. Evaluation of the association nitrogen fixing bacterias interspecific – rice lines – nitrogen, in typic haplustalf. Ibagué, Colombia Evaluación de la asociación bacterias fijadoras de nitrógeno – líneas interespecíficas de arroz–nitrógeno, en Typic haplustalf. Ibagué, Colombia

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    Bonilla Correa Carmen Rosa

    2008-03-01

    Full Text Available The study was carried out at the Cauchitos farm, Ibague municipality department of Tolima, with bounds: North 4°23'51"; and west 75°9'7";, 979 ansm, the average temperature is 24,3°C, tropical dry forest (bs–t in the Holdridge classification. The purpose of this study was to evaluate the association between the nitrogen fixation bacteries with and without inoculo in 10 interespecific rice lines with three nitrogen dosis (0, 50 and 100% de 250 kg/ ha–1 and three repetitions. The inoculation was realized with 108 former units of colonies per millimeter. 2.260 bacteries of the generums Azotobacter spp y Azospirrillum spp., and identification the species: Azospirillum brasilense, Azospirillum lipoferum, Azospirillum amazonense, were identified and from the genus Azotobacter were identified the species: A. choroococcum, A. vinelandii, A. paspali and A. veijerinckii. Weren't found none significative differences after the inoculation. Azotobacter spp and Azospirillum spp. were typical generums of the bacterian flora in the rice plantation and in field conditions were effect of the treatment effects in the bacterian . The Azotobacter spp was the predominant in generum in each one of the treatments.El estudio se llevó a cabo en la hacienda Cauchitos, municipio de Ibagué, departamento del Tolima (Norte 4° 23' 51"; y Oeste 75° 9' 7";, 979 msnm, 24.3°C, bosque seco tropical (bs–T, con el objetivo de evaluar las asociaciones entre bacterias fijadoras de nitrógeno con inóculo y sin él en diez líneas interespecíficas de arroz, con tres dosis de nitrógeno (0%, 50% y 100% de 250 kg/ha–1 y tres repeticiones por tratamiento. La inoculación se

  1. CARACTERIZACIÓN DE BACTERIAS DIAZOTRÓFICAS ASIMBIÓTICAS ASOCIADAS AL EUCALIPTO (Eucalyptus sp. EN CODAZZI, CESAR.

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    Dolly Melissa Obando Castellanos

    2010-09-01

    Full Text Available Se evaluó el efecto de las épocas climáticas (lluvia y sequía y del estrato de la muestra (Suelo rizosférico, raíces y hojas sobre la población de los géneros Azotobacter, Beijerinckia, Derxia, Azospirillum, Herbaspirillum, Gluconacetobacter y Burkholderia en el Eucalipto (Eucalyptus sp.. Así mismo, se evalúo su capacidad en la producción de compuestos indólicos como promotores del crecimiento vegetal y su actividad de reducción de acetileno como indicador de la fijación biológica de nitrógeno. Los resultados no registraron diferencias estadísticas significativas en el test de Tukey (P ≤ 0.05 en la población con respecto a la época climática. Con respecto al estrato de muestra, los aislamientos tentativos a Herbaspirillum sp. y Azospirillum sp. presentaron diferencias significativas en suelo rizosférico y raíces. Se obtuvieron 44 aislamientos de los cuales se agruparon por caracterización fenotípica como: 14 presuntivos del género Beijerinckia sp., 12 de Azotobacter sp., 8 de Derxia sp., 4 de Herbarpirillum sp., 5 de Azospirillum sp., 1 de Gluconacetobacter sp. y 1 de Burkholderia sp. Por su alto potencial fueron seleccionados y criopreservados los aislamientos C27, C26, C25 y C45, las cuales presentaron los mejores valores de eficiencia in vitro, superando valores de producción de las cepas de referencia utilizadas (A. chroococcum (AC-01 y A. brasilense (SP7.

  2. Microalgae growth-promoting bacteria: A novel approach in wastewater treatment

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    Luz E. de-Bashan

    2003-07-01

    Full Text Available Plant growth-promoting bacteria (PGPB from the genus Azospirillum are known to enhance the growth of numerous agricultural crops. The use of these bacteria is proposed as "micro-algae-growth promoting bacteria" (MGPB for enhancing freshwater micro-algae Chlorella vulgaris and C. sorokiniana capadty to clean polluted water. The deliberate inoculation of Chlorella sp. with a terrestrial PGPB has not been reported prior to these studies, perhaps because of the different origin of the two micro-organisms. Chlorella spp. is not known to harbour any plant growth-promoting bacteria and Azospirillum sp. is rarely used for inoculation in aquatic environments. Co-immobilisation of C. vulgaris and A. brasilense Cd in small alginate beads resulted in significant increases in numerous micro-algae growth parameters. Dry and fresh weight, total number of cells, micro-algal cluster (colonies size within the bead, number of micro-algal cells per cluster and micro-algal pigments levels significantly increased. Lipids and the variety of fatty adds also significantly increased, as did the combination of micro-algae. MGPB had superior capacity for removing ammonium and phosphorus from polluted synthetic and municipal wastewaters than the micro-algae by itself. Other PGPB (i.e. Flavobacterium sp. Azospirillum sp. and Azotobacter sp. are currently being tested in aquaculture; carp farming using enhanced phytoplankton growth and stabilising mass marine micro-algae culture for use as feed for marine organisms are both retuming promising results. This aspect of PGPB effect on water micro-organisms is currently in its infancy. We pro pose that co-immobilising micro-algae and plant growth-promoting bacteria represent an effective means of increasing micro-algal populations and also their capacity for cleaning polluted water. Key words: PGPB; micro-algae; wastewater treatment; co-immobilised

  3. Potential of plant growth promoting rhizobacteria and chemical fertilizers on soil enzymes and plant growth

    International Nuclear Information System (INIS)

    Nosheen, A.; Bano, A.

    2014-01-01

    The present investigation deals with the role of Plant Growth Promoting Rhizobacteria and chemical fertilizers alone or in combination on urease, invertase and phosphatase activities of rhizospheric soil and also on general impact on growth of safflower cvv. Thori and Saif-32. The PGPR (Azospirillum brasilense and Azotobacter vinelandii) were applied at 10/sup 6/ cells/mL as seed inoculation prior to sowing. Chemical fertilizers were applied at full (Urea 60 Kg ha/sup -1/ and Diammonium phosphate (DAP) 30 Kg ha/sup -1/), half (Urea 30 Kg ha/sup -1/ and DAP 15 Kg ha/sup -1/) and quarter doses (Urea 15 Kg ha-1 and DAP 7.5 Kg ha/sup -1/) during sowing. The chemical fertilizers and PGPR enhanced urease and invertase activities of soil. Presence of PGPR in combination with quarter and half doses of chemical fertilizers further augmented their effect on soil enzymes activities. The soil phosphatase activity was greater in Azospirillum and Azotobacter in combination with half dose of chemical fertilizers. Maximum increase in leaf melondialdehyde content was recorded in full dose of chemical fertilizers whereas coinoculation treatment exhibited significant reduction in cv. Thori. Half and quarter dose of chemical fertilizers increased the shoot length of safflower whereas maximum increase in leaf protein was recorded in Azotobacter in combination with full dose of chemical fertilizers. Root length was improved by Azospirillum and Azotobacter in combination with quarter dose of chemical fertilizers. Leaf area and chlorophyll contents were significantly improved by Azotobacter in combination with half dose of chemical fertilizers. It is inferred that PGPR can supplement 50 % chemical fertilizers for better plant growth and soil health. (author)

  4. Effect of Biofertilizers on the Yield and Yield Components of Black Cumin (Nigella sativa L.

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    S Khorramdel

    2011-02-01

    Full Text Available Abstract Application of biological fertilizers is one of the most important methods for plant nutrition in ecological agriculture. In order to investigate the effect of biofertilizers on yield and yield components of black cumin (Nigella sativa L., a field experiment was arranged in a randomized complete block design with three replications during 2007 growing season at the Agricultural Research Station of Ferdowsi University of Mashhad. Treatments included: (A Azotobacter paspali, (B Azospirillum brasilense, (C the fungus of Glomus intraradaices, C+A, C+B, A+B, A+B+C, and control without no biofertilizers. In all treatments except control, the amounts of 15 mg of each biofertilizer were applied to 110 g of seeds. Results indicated that application of biofertilizers enhanced yield and yield components and decreased percentage of hollow capsules. Plant performance was better with application of Azospirillum plus mycorrhiza and a mixture of Azotobacter, Azospirillum and mycorrhiza in terms of yield determining criteria. The maximum and minimum amounts of seed yield were recorded in the B+C treatment with 41.4 gm-2, and control with 24.1 gm-2, respectively. There was no significant correlation between number of capsules per plant and seed yield, but the positive and significant correlation between number of branches per plant, number of seeds per capsule, 1000-seed weight and seed yield was observed. This study showed that application of suitable biofertilizers could increase yield and yield components of black cumin. Keywords: Biofertilizer, Ecological agriculture, Medicinal plants, Plant growth promoting rhizobacteria

  5. Genome-wide identification of microRNA and siRNA responsive to endophytic beneficial diazotrophic bacteria in maize.

    Science.gov (United States)

    Thiebaut, Flávia; Rojas, Cristian A; Grativol, Clícia; Motta, Mariana Romeiro; Vieira, Tauan; Regulski, Michael; Martienssen, Robert A; Farinelli, Laurent; Hemerly, Adriana S; Ferreira, Paulo C G

    2014-09-06

    Small RNA (sRNA) has been described as a regulator of gene expression. In order to understand the role of maize sRNA (Zea mays-hybrid UENF 506-8) during association with endophytic nitrogen-fixing bacteria, we analyzed the sRNA regulated by its association with two diazotrophic bacteria, Herbaspirillum seropedicae and Azospirillum brasilense. Deep sequencing analysis was done with RNA extracted from plants inoculated with H. seropedicae, allowing the identification of miRNA and siRNA. A total of 25 conserved miRNA families and 15 novel miRNAs were identified. A dynamic regulation in response to inoculation was also observed. A hypothetical model involving copper-miRNA is proposed, emphasizing the fact that the up-regulation of miR397, miR398, miR408 and miR528, which is followed by inhibition of their targets, can facilitate association with diazotrophic bacteria. Similar expression patterns were observed in samples inoculated with A. brasilense. Moreover, novel miRNA and siRNA were classified in the Transposable Elements (TE) database, and an enrichment of siRNA aligned with TE was observed in the inoculated samples. In addition, an increase in 24-nt siRNA mapping to genes was observed, which was correlated with an increase in methylation of the coding regions and a subsequent reduction in transcription. Our results show that maize has RNA-based silencing mechanisms that can trigger specific responses when plants interact with beneficial endophytic diazotrophic bacteria. Our findings suggest important roles for sRNA regulation in maize, and probably in other plants, during association with diazotrophic bacteria, emphasizing the up-regulation of Cu-miRNA.

  6. Effect of immobilized rhizobacteria and organic amendment in bulk and rhizospheric soil of Cistus albidus L.

    Science.gov (United States)

    Mengual, Carmen Maria; del Mar Alguacil, Maria; Roldan, Antonio; Schoebitz, Mauricio

    2013-04-01

    A field experiment was carried out to assess the effectiveness of the immobilized microbial inoculant and the addition of organic olive residue. The microbial inoculant contained two rhizobacterial species identified as Azospirillum brasilense and Pantoea dispersa immobilized in a natural inert support. Bacterial population densities were 3.5×109 and 4.1×109 CFU g-1 of A. brasilense M3 and P. dispersa C3, respectively. The amendment used was the organic fraction extracted with KOH from composted "alperujo". The raw material was collected from an olive-mill and mixed with fresh cow bedding as bulking agent for composting. The inoculation of rhizobacteria and the addition of organic residue were employed for plant growth promotion of Cistus albidus L. and enhancement of soil physicochemical, biochemical and biological properties in a degraded semiarid Mediterranean area. One year after planting, the available phosphorus and potassium content in the amended soils was about 100 and 70% respectively higher than in the non-amended soil. Microbial inoculant and their interaction with organic residue increased the aggregate stability of the rhizosphere soil of C. albidus (by 12% with respect to control soil) while the organic residue alone not increased the aggregate stability of the rhizosphere of C. albidus. Microbial biomass C content and enzyme activities (dehydrogenase, urease, protease-BAA and alkaline phosphatase) of the rhizosphere of C. albidus were increased by microbial inoculant and organic residue interaction but not by microbial inoculation alone. The microbial inoculant and organic residue interaction were the most effective treatment for stimulating the roots dry weight of C. albidus (by 133% with respect to control plants) and microbial inoculant was the most effective treatment for increase the shoot dry weigh of plants (by 106% with respect to control plants). The combined treatment, involving microbial inoculant and addition of the organic residue

  7. Alternative rooting induction of semi-hardwood olive cuttings by several auxin-producing bacteria for organic agriculture systems

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    M. C. Montero-Calasanz

    2013-01-01

    Full Text Available Southern Spain is the largest olive oil producer region in the world. In recent years organic agriculture systems have grown exponentially so that new alternative systems to produce organic olive cuttings are needed. Several bacterial isolates, namely Pantoea sp. AG9, Chryseobacterium sp. AG13, Chryseobacterium sp. CT348, Pseudomonas sp. CT364 and Azospirillum brasilense Cd (ATCC 29729, have been used to induce rooting in olive semi-hardwood cuttings of Arbequina, Hojiblanca and Picual cultivars of olive (Olea europea L. The first four strains were previously selected as auxin-producing bacteria and by their ability to promote rooting in model plants. They have been classified on the basis of their 16S rDNA gene sequence. The known auxin producer A. brasilense Cd strain has been used as a reference. The inoculation of olive cuttings was performed in two different ways: (i by dipping cuttings in a liquid bacterial culture or (ii by immersing them in a paste made of solid bacterial inoculant and sterile water. Under nursery conditions all of the tested bacterial strains were able to induce the rooting of olive cuttings to a similar or greater extent than the control cuttings treated with indole-3-butyric acid (IBA. The olive cultivars responded differently depending on the bacterial strain and the inoculation method. The strain that consistently gave the best results was Pantoea sp. AG9, the only one of the tested bacterial strains to express the enzyme 1-aminocyclopropane-1-carboxylate (ACC deaminase. The results are also discussed in terms of potential commercial interest and nursery feasibility performance of these strains.

  8. The Effect of Plant Growth Promoting Rhizobacteria (PGPR and Phosphate Solubilizing Microorganism (PSM on Yield and Yield Components of Wheat (cv. N80 under Different Nitrogen and Phosphorous Fertilizers Levels in Greenhouse Condition

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    S. H Bahari saravi

    2013-04-01

    Full Text Available In order to evaluate the effect of plant growth promoting rhizobacteria (PGPR and phosphate solubilizing microorganism (PSM on yield and yield components of wheat a pot experiment was conducted at Sari Agricultural Sciences and Natural Resources University during 2009. Experiment was arranged in factorial based on completely randomized design in three replicates. Treatments were included bio-fertilizer in four levels (non-inoculation control, Phosphate Barvare 2 (Pseudomonas fluorescens+Bacillus subtilis, Supernitroplus (Azotobacter brasilense+Azospirillum lipoferum and Nitroxine (Azospirillum + Pseudomona + Bacillus, three levels of chemical nitrogen fertilizer (0, 75 and 150 kg urea/ha and three levels of phosphorus fertilizer (0, 60 and 120 kg super phosphate triple/ha. Results showed that the studied treatments (biofertilizer, nitrogen and phosphate inorganic fertilizers had significant effect on grain number per spike, 1000 grain weight, grain yield, straw yield, biological yield and harvest index. Interaction effect between biofertilizer and chemical fertilizers was significant in terms of grain yield. The maximum grain yield was resulted from simultaneously applying of Nitroxine and 75 kg ha-1 nitrogen fertilizer. By contrast, the highest straw yield was obtained when 150 kg nitrogen fertilizer was used. Grain yield had the maximum correlation with biological yield (r=0.85**. Grain yield positively and significantly correlated with grain number per spike (r=0.73**, 1000 grain weight (r=0.68**, straw yield (r=0.56** and harvest index (r=0.69**. In conclusion biofertilizer inoculations could reduce application of nitrogen and phosphorus chemical fertilizers and increase plant performance.

  9. Bacillus pumilus ES4: candidate plant growth-promoting bacterium to enhance establishment of plants in mine tailings

    Science.gov (United States)

    de-Bashan, Luz E.; Hernandez, Juan-Pablo; Bashan, Yoav; Maier, Raina

    2014-01-01

    Three plant growth-promoting bacteria (PGPB; Bacillus pumilus ES4, B. pumilus RIZO1, and Azospirillum brasilense Cd) were tested for their ability to enhance plant growth and development of the native Sonoran Desert shrub quailbush (Atriplex lentiformis) and for their effect on the native bacterial community in moderately acidic, high-metal content (AHMT) and in neutral, low metal content natural tailings (NLMT) in controlled greenhouse experiments. Inoculation of quailbush with all three PGPB significantly enhanced plant growth parameters, such as germination, root length, dry weight of shoots and roots, and root/shoot ratio in both types of tailings. The effect of inoculation on the indigenous bacterial community by the most successful PGPB Bacillus pumilus ES4 was evaluated by denaturating gradient gel electrophoresis (PCR-DGGE) fingerprinting and root colonization was followed by specific fluorescent in situ hybridization (FISH). Inoculation with this strain significantly changed the bacterial community over a period of 60 days. FISH analysis showed that the preferred site of colonization was the root tips and root elongation area. This study shows that inoculation of native perennial plants with PGPB can be used for developing technologies for phytostabilizing mine tailings. PMID:25009362

  10. Growth promoting characteristics of rhizobacteria and AM Fungi for biomass amelioration of Zea mays

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    Kumar Manoj

    2015-01-01

    Full Text Available Plant growth promoting rhizobacteria (PGPR and mycorrhiza were evaluated on the growth (biomass and yield of Zea mays. In the present study, selective rhizospheric PGPR (Azotobacter chroococcum, Pseudomonas aeruginosa, Azospirillum brasilense and Streptomyces sp. and a combination of six strains of arbuscular mycorrhizal fungi (AMF (Acaulospora morrowae, Gigaspora margarita, Glomus constrictum, Glomus mossae, Glomus aggregatum and Scutellospora calospora were isolated and identified with standard methods and 16S rRNA sequence analysis. PGPR and AMF were checked for their growth-promoting behavior under specific treatment conditions. The 30-48-day-old treated plants in all combinations showed a significantly higher mass value. The average dry weight from the shoot was in a range from 41-52% as compared to the control. This increase also translated into a higher mass value of the roots. Overall, an 82% growth rate was observed in terms of height as the consequence of biomass production, specifically in the case of AMF + rhizobacteria combination. We report an efficient, sustainable and cost-effective biofertilizer for enhanced biomass of Z. mays, one of the staple food crops worldwide.

  11. History on the biological nitrogen fixation research in graminaceous plants: special emphasis on the Brazilian experience.

    Science.gov (United States)

    Baldani, José I; Baldani, Vera L D

    2005-09-01

    This review covers the history on Biological Nitrogen Fixation (BNF) in Graminaceous plants grown in Brazil, and describes research progress made over the last 40 years, most of which was coordinated by Johanna Döbereiner. One notable accomplishment during this period was the discovery of several nitrogen-fixing bacteria such as the rhizospheric (Beijerinckia fluminensis and Azotobacter paspali), associative (Azospirillum lipoferum, A. brasilense, A. amazonense) and the endophytic (Herbaspirillum seropedicae, H. rubrisubalbicans, Gluconacetobacter diazotrophicus, Burkholderia brasilensis and B. tropica). The role of these diazotrophs in association with grasses, mainly with cereal plants, has been studied and a lot of progress has been achieved in the ecological, physiological, biochemical, and genetic aspects. The mechanisms of colonization and infection of the plant tissues are better understood, and the BNF contribution to the soil/plant system has been determined. Inoculation studies with diazotrophs showed that endophytic bacteria have a much higher BNF contribution potential than associative diazotrophs. In addition, it was found that the plant genotype influences the plant/bacteria association. Recent data suggest that more studies should be conducted on the endophytic association to strengthen the BNF potential. The ongoing genome sequencing programs: RIOGENE (Gluconacetobacter diazotrophicus) and GENOPAR (Herbaspirillum seropedicae) reflect the commitment to the BNF study in Brazil and should allow the country to continue in the forefront of research related to the BNF process in Graminaceous plants.

  12. Compatible bacterial mixture, tolerant to desiccation, improves maize plant growth.

    Science.gov (United States)

    Molina-Romero, Dalia; Baez, Antonino; Quintero-Hernández, Verónica; Castañeda-Lucio, Miguel; Fuentes-Ramírez, Luis Ernesto; Bustillos-Cristales, María Del Rocío; Rodríguez-Andrade, Osvaldo; Morales-García, Yolanda Elizabeth; Munive, Antonio; Muñoz-Rojas, Jesús

    2017-01-01

    Plant growth-promoting rhizobacteria (PGPR) increase plant growth and crop productivity. The inoculation of plants with a bacterial mixture (consortium) apparently provides greater benefits to plant growth than inoculation with a single bacterial strain. In the present work, a bacterial consortium was formulated containing four compatible and desiccation-tolerant strains with potential as PGPR. The formulation had one moderately (Pseudomonas putida KT2440) and three highly desiccation-tolerant (Sphingomonas sp. OF178, Azospirillum brasilense Sp7 and Acinetobacter sp. EMM02) strains. The four bacterial strains were able to adhere to seeds and colonize the rhizosphere of plants when applied in both mono-inoculation and multi-inoculation treatments, showing that they can also coexist without antagonistic effects in association with plants. The effects of the bacterial consortium on the growth of blue maize were evaluated. Seeds inoculated with either individual bacterial strains or the bacterial consortium were subjected to two experimental conditions before sowing: normal hydration or desiccation. In general, inoculation with the bacterial consortium increased the shoot and root dry weight, plant height and plant diameter compared to the non-inoculated control or mono-inoculation treatments. The bacterial consortium formulated in this work had greater benefits for blue maize plants even when the inoculated seeds underwent desiccation stress before germination, making this formulation attractive for future field applications.

  13. Halotolerant/alkalophilic bacteria associated with the cyanobacterium Arthrospira platensis (Nordstedt Gomont that promote early growth in Sorghum bicolor (L. Moench

    Directory of Open Access Journals (Sweden)

    Gómez G. Liliana Cecilia

    2012-04-01

    Full Text Available

    Arthrospira platensis associated bacteria (APAB identified through molecuar biology like Bacillus okhensis, Indibacter alkaliphilus and Halomonas sp., are also producing 3-indol acetic acid (IAA, these bacteria was used in early plant growth promotion tests over Sorghum bicolor, these bioassay was considered indirect evidence to suggest that APAB also may have stimulatory effects over A. platensis growth naturally. I. alkaliphilus and B. okhensis enhanced early germination of S. bicolor seads, with better results than that achieved by Azospirillum brasilense, bacterium used like reference as a common plant growth promoting rizobacteria. The three APAB enhanced significative differences (P≤0.05 over morphoagronomic parameters, I. alkaliphilus and B. okhensis exhibit better resoults in elongation stimulation and root and foliage dry weight. Above evidence suggest this bacteria like plant growth promoting and it recomended testing with A. platensis axenic cultures and its associated bactteri for understanding true interaction between them.

  14. Compatible bacterial mixture, tolerant to desiccation, improves maize plant growth.

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    Dalia Molina-Romero

    Full Text Available Plant growth-promoting rhizobacteria (PGPR increase plant growth and crop productivity. The inoculation of plants with a bacterial mixture (consortium apparently provides greater benefits to plant growth than inoculation with a single bacterial strain. In the present work, a bacterial consortium was formulated containing four compatible and desiccation-tolerant strains with potential as PGPR. The formulation had one moderately (Pseudomonas putida KT2440 and three highly desiccation-tolerant (Sphingomonas sp. OF178, Azospirillum brasilense Sp7 and Acinetobacter sp. EMM02 strains. The four bacterial strains were able to adhere to seeds and colonize the rhizosphere of plants when applied in both mono-inoculation and multi-inoculation treatments, showing that they can also coexist without antagonistic effects in association with plants. The effects of the bacterial consortium on the growth of blue maize were evaluated. Seeds inoculated with either individual bacterial strains or the bacterial consortium were subjected to two experimental conditions before sowing: normal hydration or desiccation. In general, inoculation with the bacterial consortium increased the shoot and root dry weight, plant height and plant diameter compared to the non-inoculated control or mono-inoculation treatments. The bacterial consortium formulated in this work had greater benefits for blue maize plants even when the inoculated seeds underwent desiccation stress before germination, making this formulation attractive for future field applications.

  15. Differential growth responses of Brachypodium distachyon genotypes to inoculation with plant growth promoting rhizobacteria.

    Science.gov (United States)

    do Amaral, Fernanda P; Pankievicz, Vânia C S; Arisi, Ana Carolina M; de Souza, Emanuel M; Pedrosa, Fabio; Stacey, Gary

    2016-04-01

    Plant growth promoting rhizobacteria (PGPR) can associate and enhance the growth of important crop grasses. However, in most cases, the molecular mechanisms responsible for growth promotion are not known. Such research could benefit by the adoption of a grass model species that showed a positive response to bacterial inoculation and was amenable to genetic and molecular research methods. In this work we inoculated different genotypes of the model grass Brachypodium distachyon with two, well-characterized PGPR bacteria, Azospirillum brasilense and Herbaspirillum seropedicae, and evaluated the growth response. Plants were grown in soil under no nitrogen or with low nitrogen (i.e., 0.5 mM KNO3). A variety of growth parameters (e.g., shoot height, root length, number of lateral roots, fresh and dry weight) were measured 35 days after inoculation. The data indicate that plant genotype plays a very important role in determining the plant response to PGPR inoculation. A positive growth response was observed with only four genotypes grown under no nitrogen and three genotypes tested under low nitrogen. However, in contrast, relatively good root colonization was seen with most genotypes, as measured by drop plate counting and direct, microscopic examination of roots. In particular, the endophytic bacteria H. seropedicae showed strong epiphytic and endophytic colonization of roots.

  16. Robust biological nitrogen fixation in a model grass-bacterial association.

    Science.gov (United States)

    Pankievicz, Vânia C S; do Amaral, Fernanda P; Santos, Karina F D N; Agtuca, Beverly; Xu, Youwen; Schueller, Michael J; Arisi, Ana Carolina M; Steffens, Maria B R; de Souza, Emanuel M; Pedrosa, Fábio O; Stacey, Gary; Ferrieri, Richard A

    2015-03-01

    Nitrogen-fixing rhizobacteria can promote plant growth; however, it is controversial whether biological nitrogen fixation (BNF) from associative interaction contributes to growth promotion. The roots of Setaria viridis, a model C4 grass, were effectively colonized by bacterial inoculants resulting in a significant enhancement of growth. Nitrogen-13 tracer studies provided direct evidence for tracer uptake by the host plant and incorporation into protein. Indeed, plants showed robust growth under nitrogen-limiting conditions when inoculated with an ammonium-excreting strain of Azospirillum brasilense. (11)C-labeling experiments showed that patterns in central carbon metabolism and resource allocation exhibited by nitrogen-starved plants were largely reversed by bacterial inoculation, such that they resembled plants grown under nitrogen-sufficient conditions. Adoption of S. viridis as a model should promote research into the mechanisms of associative nitrogen fixation with the ultimate goal of greater adoption of BNF for sustainable crop production. © 2015 The Authors The Plant Journal © 2015 John Wiley & Sons Ltd.

  17. Densidade e diversidade fenotípica de bactérias diazotróficas endofíticas em solos de mineração de bauxita, em reabilitação Density and phenotypic diversity of endophytic nitrogen fixing bacteria in soils under rehabilitation after bauxite mining

    Directory of Open Access Journals (Sweden)

    R. Melloni

    2004-02-01

    Full Text Available Bactérias diazotróficas endofíticas contribuem para o desenvolvimento das plantas por meio da fixação biológica do nitrogênio, produção e liberação de substâncias reguladoras do crescimento vegetal, podendo, assim, facilitar a revegetação de solos degradados por atividades antrópicas. No entanto, pouco se conhece sobre as populações destas bactérias em solos ou plantas de áreas de mineração. Objetivando avaliar o efeito de diferentes tipos de vegetação e tempo de reabilitação de áreas degradadas por mineração de bauxita na densidade e diversidade de algumas espécies de bactérias diazotróficas endofíticas, realizaram-se, em duas épocas, amostragens de solo, de dois ambientes distintos, submetidos a diferentes processos de reabilitação. A densidade, avaliada pelo número mais provável, utilizando os meios de cultura: NFb, JNFb e Fam, para Azospirillum brasilense e A. lipoferum, Herbaspirillum spp. e A. amazonense, respectivamente, variou de 0 a 2,0 x 10(4 bactérias por grama de solo e mostrou que o tipo de vegetação influiu nas populações destas bactérias. Foram encontradas densidades maiores em solos revegetados com gramíneas: braquiária (Brachiaria decumbens, capim-azevém (Lolium multiflorum e capim-gordura (Melinis minutiflora. Contudo, estas densidades podem ser consideradas baixas, se comparadas às de solos agrícolas, e não apresentaram relação com o tempo de reabilitação da área. Foram encontrados 36 fenótipos culturais em meio batata, entre os 72 isolados obtidos dos três meios de cultura utilizados. A partir destes, foram formados sete grandes grupos com similaridade superior ou igual a 63 %, dos quais cinco, representando 62,5 % do total de isolados obtidos, continham as estirpes-tipo de Burkholderia brasilensis, Herbaspirillum seropedicae e Azospirillum spp. (A. brasilense, A. amazonense, A. lipoferum, A. irakense. Apesar da baixa densidade, este grupo de bactérias apresentou alta

  18. Effect of plant growth-promoting bacteria on the growth and fructan production of Agave americana L.

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    Neyser De La Torre-Ruiz

    Full Text Available ABSTRACT The effect of plant growth-promoting bacteria inoculation on plant growth and the sugar content in Agave americana was assessed. The bacterial strains ACO-34A, ACO-40, and ACO-140, isolated from the A. americana rhizosphere, were selected for this study to evaluate their phenotypic and genotypic characteristics. The three bacterial strains were evaluated via plant inoculation assays, and Azospirillum brasilense Cd served as a control strain. Phylogenetic analysis based on the 16S rRNA gene showed that strains ACO-34A, ACO-40 and ACO-140 were Rhizobium daejeonense, Acinetobacter calcoaceticus and Pseudomonas mosselii, respectively. All of the strains were able to synthesize indole-3-acetic acid (IAA, solubilize phosphate, and had nitrogenase activity. Inoculation using the plant growth-promoting bacteria strains had a significant effect (p < 0.05 on plant growth and the sugar content of A. americana, showing that these native plant growth-promoting bacteria are a practical, simple, and efficient alternative to promote the growth of agave plants with proper biological characteristics for agroindustrial and biotechnological use and to increase the sugar content in this agave species.

  19. Trace cobalt speciation in bacteria and at enzymic active sites using emission Moessbauer spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Kamnev, A.A.; Antonyuk, L.P.; Smirnova, V.E.; Serebrennikova, O.B. [Laboratory of Biochemistry, Institute of Biochemistry and Physiology of Plants and Microorganisms, Russian Academy of Sciences, Saratov (Russian Federation); Kulikov, L.A.; Perfiliev, Yu.D. [Laboratory of Nuclear Chemistry Techniques, Department of Radiochemistry, Faculty of Chemistry, Moscow State University (Russian Federation)

    2002-02-01

    {sup 57}Co emission Moessbauer spectroscopy (EMS) allows the chemical state of cobalt, as influenced by its coordination environment, to be monitored in biological samples at its physiological (trace) concentrations. To draw attention to EMS as a valuable tool for speciation of cobalt in biocomplexes, the process of cobalt(II) metabolism in cells of the plant growth-promoting rhizobacterium Azospirillum brasilense Sp245 was investigated using EMS of {sup 57}Co{sup II}-doped bacterial cells. EMS measurements also showed {sup 57}Co{sup II}-activated glutamine synthetase (GS, a key enzyme of nitrogen metabolism, isolated from this bacterium) to have two different cobalt(II) forms at its active sites, in agreement with data available on other bacterial GSs. Chemical after-effects following electron capture by the nucleus of the parent {sup 57}Co{sup II} during the {sup 57}Co{yields}{sup 57}Fe transition, which contribute to the formation of a stabilised daughter {sup 57}Fe{sup III} component along with the nucleogenic {sup 57}Fe{sup II} forms, are also briefly considered. (orig.)

  20. Structure of insoluble immune complexes as studied by spectroturbidimetry and dynamic light scattering

    Science.gov (United States)

    Khlebtsov, Boris N.; Burygin, Gennadii L.; Matora, Larisa Y.; Shchyogolev, Sergei Y.; Khlebtsov, Nikolai G.

    2004-07-01

    We describe two variants of a method for determining the average composition of insoluble immune complex particles (IICP). The first variant is based on measuring the specific turbidity (the turbidity per unit mass concentration of the dispersed substance) and the average size of IICP determined from dynamic light scattering (DLS). In the second variant, the wavelength exponent (i.e., the slope of the logarithmic turbidity spectrum) is used in combination with specific turbidity measurements. Both variants allow the average biopolymer volume fraction to be determined in terms of the average refractive index of IICP. The method is exemplified by two experimental antigen+antibody systems: (i) lipopolysaccharide-protein complex (LPPC) of Azospirillum brasilense Sp245+rabbit anti-LPPC; and (ii) human IgG (hIgG)+sheep anti-hIgG. Our measurements by the two methods for both types of systems gave, on the average, the same result: the volume fraction of the IICP biopolymers is about 30%; accordingly, the volume fraction of buffer solvent is 70%.

  1. Oviposition Attractancy of Bacterial Culture Filtrates: response of Culex quinquefasciatus

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    S Poonam

    2002-04-01

    Full Text Available Oviposition attractants could be used for monitoring as well as controlling mosquitoes by attracting them to lay eggs at chosen sites. In the present study, culture filtrates of seven bacterial species were tested for their attractancy against gravid females of Culex quinquefasciatus. When their oviposition active indices (OAI were studied, the culture filtrates of Bacillus cereus and Pseudomonas fluorescens exhibited oviposition attractancy (OAI = >0.3 at 100 ppm and the OAI were respectively 0.70 and 0.47. Culture filtrates of B. thuringiensis var. israelensis (wild type, B. t. var. israelensis (mutant and B. sphaericus showed attractancy at 2000 ppm with OAI of respectively 0.71, 0.59 and 0.68. However, the OAI of B. megaterium as well as Azospirillum brasilense was 0.13 (at 2000 ppm, which was less than 0.3 required to be considered them as attractants. When the oviposition attractancy of the bacterial culture filtrates were compared with that of a known oviposition attractant, p-cresol (at 10 ppm, the culture filtrates of B. t. var. israelensis (wild type and B. cereus were found to be more active than p-cresol, respectively with 64.2 and 54.3% oviposition.

  2. The effect of ectomycorrhizal fungi and bacteria on pine seedlings

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    Hanna Dahm

    2014-08-01

    Full Text Available The effect of ecomycorrhizal fungi (Hebelon crustuliniforme(Bull.: Fr. Quél. 5392 and Pisolithus tinctorius (Pers. Coker et Couch 5335 and bacteria (Bacillus polymyxa and Azospirillum brasilense. associated with mycorrhizas on the growth of pine seedligs was investigated. In addition the influence of bacteria on fungal biomass production and the relationship between ectomycorrhizal fungi and fungi pathogenic to root of pine seedlings were determined. In general, the shoot/root ratio was higher in plants inoculated with Hebeloma crustuliniforme and bacteria than in the control seedlings (grown only under sterile conditions. In non-sterile substrate the root/shoot ratio of the mycorrhizal seedlings was lower as compared to the control. Similar phenomenon was noted in plants inoculated with the mycorrhizal fungus Pisolithus tinetorius. The bacteria used as well as the time of introduction of these organisms into the cultures of mycorrhiza fungi affected the production of fungal biomass. Hebeloma crustuliniforme and Pisolithus tinctorius inhibited the growth of Rizoctonia solani and Fusarium oxysporum fungi pathogenic to pine seedlings.

  3. Bionota: Bacterias promotoras de crecimiento de microalgas: una nueva aproximación en el tratamiento de aguas residuales Microalgae growth-promoting bacteria: A novel approach in wastewater treatment

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    Bashan Yoav

    2003-12-01

    Full Text Available Las bacterias promotoras de crecimiento en plantas (PGPB del género Azospirillum son conocidas porque mejo­ran el crecimiento de numerosas cosechas agrícolas; sin embargo, el presente trabajo pretende extender el uso de estas bacterias a "bacterias promotoras de crecimiento de microalgas" (MPGB para aumentar la capacidad de las microalgas de eliminar nutrientes de aguas residuales. La inoculación deliberada de las microalgas Chlorella spp. con PGPB de origen terrestre no ha sido reportada con anterioridad, tal vez debido al origen diferente de estos dos microorganismos. Al inmovilizar de manera conjunta Chlorella vulgaris y Azospirillum brasilense Cd en esferas de alginato, se obtuvo como resultado un aumento significativo en varios parámetros de crecimiento de la microalga, como el peso fresco y seco, el número total de células, el tamaño de las colonias de microalgas dentro de la esfera, el número de organismos por colonia y la concentración de pigmentos. Además, aumenta­ron los lípidos y la variedad de ácidos grasos. La microalga combinada con la MGPB tiene una mayor capacidad de eliminar amonio y fósforo tanto en agua residual sintética como en agua residual doméstica. Actualmente se ha estado experimentando con otras PGPB (Flavobacterium sp. Azospirillum sp. y Azotobacter sp. para propósitos acuícolas; por ejemplo aumentar el crecimiento de fitoplancton utilizado en el cultivo de carpas y estabilizar cultivos masivos de microalgas marinas utilizadas como alimento para organismos marinos, todo esto con resul­tados promisorios. Si bien el efecto de las PGPB en microorganismos acuáticos aún no ha sido suficientemente explorado, proponemos que la co-inmovilización de microalgas y bacterias promotoras de crecimiento es un medio efectivo para aumentar la población microalgal y también su capacidad de limpiar aguas residuales. Palabras clave: PGPB; microalgas; biotratamiento de aguas residuales; co

  4. Desempenho agronômico a campo de híbridos de milho inoculados com Azospirillum

    OpenAIRE

    Quadros,Patricia Dörr de; Roesch,Luiz Fernando Wurdig; Silva,Paulo Régis Ferreira da; Vieira,Vladirene Macedo; Roehrs,Dioni Dinael; Camargo,Flávio Anastácio de Oliveira

    2014-01-01

    O uso de inoculantes na cultura do milho tem sido cada vez mais valorizado, em vista dos benefícios que pode trazer à cultura, como a fixação biológica do nitrogênio e o aumento da quantidade de raízes. Isto pode melhorar a absorção de água e nutrientes pela planta, contribuindo para o desenvolvimento do milho, principalmente em períodos de seca. Este estudo foi desenvolvido com o objetivo de avaliar, em condições de campo, as características agronômicas e o rendimento de grãos de híbridos de...

  5. Effects of Azotobacter and Azospirillum and Levels of Manure on Quantitative and Qualitative Traits of Safflower (Carthamus tinctorius L.

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    maryam shahraki

    2016-07-01

    Full Text Available Introduction The demand for food and agricultural products are increasing in a line of population increasing in the world (Alexandratos, 2003. It is possible to increase the quality and quantity of agricultural products via extending the farms and producing more products (Astaaraei and Koocheki, 1995. Environmental problems caused by synthetic fertilizers and the high levels of producing and introducing such chemicals, have been encouraged the researchers to apply bio-fertilizers for increasing the production in a frame of sustainable agriculture (Rajendran and Devarj, 2004. In this study, the economical yield and agronomy index of Safflower (Carthamus tinctorius L. in manure and bio fertilizers treatments was studied. Materials and method This study was conducted in Agricultural Research Institute, University of Zabol during winter season, 2013. Safflower seeds were planted in sandy loam with pH 8.2. The experimental design was factorial in a frame on randomized completely blocks with three replications. The manure as a first factor had three levels, including no treatment (control, 20 and 30 t.ha-1, while second factor was bio-fertilizer treatment with 4 levels, including no treatment (control, Azosprilium (Azo, Azotobacter (Azt and combined treatment of Azo+Azt. The processed manure and bacteria obtained from local farmers were used in this study. Populations of 108 bacteria were prepared and 24 hours before sowing, seeds were soaked in bacteria. After land preparation, experimental plots were (2.5 × 2 m2 created and treated seeds were planted (40 plants.m-2 manually and plantation was watered immediately. In this study plant height, number of heads in bush, number of seeds per head, seed weight per head, seed weight, grain and biological yield, harvest index, leaf chlorophyll, protein and oil percent were studied. Economical yield and agronomy indices of Safflower were calculated at the end of the season and data were analyzed using SAS software (2000 and the mean values were separated using Duncan test (P= 5%. Results and discussion The results showed the maximum weight of 100- seeds were treated with the manure (30 t.ha-1. In the treated plants with 30 ton/acre of manure and Azo, the high values of some parameters such as plant height, the numbers of spikes in the plants, the number of seeds in the spike, economic, yield, biological yield, harvesting index, the amount of leaf chlorophyll and percentage of seed protein were observed. In a combined treatment of manure, Azo and Azt, the highest amount of seed oil was detected. High levels of seed treatment with Azo and Azt in short period could not provide all needs of safflower because of the slow release of nutrient. Hence, combined treatment of bio-fertilizers and manure could compensate the nutrient deficiency as well as causing soil fertility and sustainable production of crops such as safflower. Results confirmed that seed inoculation with Azo and optimal levels of manure may increase safflower yield by increasing nutrient uptake, which improve plant growth and its developmental stages. It was also observed that the traits such as number of spikes per plant, number of seeds per spike, seed weight per spike, seed weight, economic and biologic yield and harvest index were significant. Conclusion It was concluded that the manure treatment, increasing the soil organic component, usable phosphorus, nitrate and other nutrients as well as improving soil texture, increase the quality and quantity of agricultural products. According to the results of this study, it seems that the inoculation with bacteria with optimal levels of manure by increasing nutrient uptake, which were associated, increase seed yield. In most characteristics, the use of bio-fertilizers with manure interaction for traits such as number of heads per plant, number of seeds per head, seed weight per head, seed weight, economic performance, biological yield and harvest index was significant.

  6. Estudio de los síntomas asociados a la pérdida de color del chayote

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    J. Cadena-Iñiguez

    2005-01-01

    Full Text Available Bajo condiciones de invernadero, se reprodujeron los síntomas de deficiencias nutrimentales iniciales asociadas a la pérdida de vigor de planta y color del fruto de Sechium edule (Jacq. Sw. llamado chayote blanco, para evaluar la respuesta de adición de nutrimentos e inoculación de microsimbiontes. Se utilizó suelo de Actopan, Veracruz, México, separándolo en capas a 0-30, 30-60, 60-90 cm y mezcla del perfil completo para determinar su fertilidad. Se aplicaron 8.29 g de (NH42SO4, 1.0 g de Ca3 (PO42, 4.4 g de K2SO4, 1.15 g de FeSO4, MnSO4 y ZnSO4, y 0.75 g de azufre, 40 g de Glomus intraradices (MA y Azospirillum brasilense por cada 30 litros de capa de suelo. Se evaluó altura de planta, clorofila y biomasa total, asimilación de CO2 y análisis con rayos-X de cortes del cuarto entrenudo inferior a la yema apical del tallo principal. El suelo evaluado presentó compuestos solubles de Cl-, SO4 2-, HCO3 -, Na+ y pH de hasta 7.9, además de 5.6, 50.3 y 4.7 veces más P, Ca2+ y Mg2+ que los valores consignados para la especie. En suelo de la capa 0-30 cm, las plantas presentaron mayor crecimiento y menor en 30-60, 60-90 cm y la mezcla. Los nutrimentos combinados con MA, así como con MA y A. brasilense fueron estadísticamente significativos. Las plantas testigo mostraron cristales formados por P, Ca, S, Si, Na y Mg obstruyendo los vasos del xilema de tallo. La evidencia experimental mostró que los síntomas iniciales asociados a chayote blanco, se deben en gran medida a deficiencias nutrimentales, siendo más evidentes en capas de suelo inferiores a 0-30 cm

  7. Densidade e diversidade fenotípica de bactérias diazotróficas não simbióticas em solos da Reserva Biológica Serra dos Toledos, Itajubá (MG

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    Talita Filomena Silva

    2011-04-01

    Full Text Available Bactérias diazotróficas não simbióticas (BDNS atuam no desenvolvimento das plantas por meio da fixação biológica de nitrogênio e também pela produção e liberação de substâncias reguladoras do crescimento vegetal. Este estudo objetivou avaliar a densidade e diversidade fenotípica desse grupo de bactérias em fragmentos de solo da Reserva Biológica Serra dos Toledos e entorno, em Itajubá/MG. Essa reserva localiza-se na Área de Proteção Ambiental da Mantiqueira, constituindo-se em uma importante área de recarga e de abrigo à flora e fauna endêmicas. Amostras de solo superficial foram coletadas em áreas com diferentes declividades na reserva, em épocas representativas das estações de inverno (setembro/2006 e verão (abril/2007. A densidade, avaliada pelo número mais provável, utilizando os meios de cultura NFb, JNFb e Fam, para Azospirillum spp., Herbaspirillum spp. e A. amazonense, respectivamente, variou de 0,12 a 75,60 (NMP x 10(5 bactérias g-1 solo seco. Foram obtidos 172 e 174 isolados, respectivamente para as amostras de inverno e verão, dos quais 30 e 55 % apresentaram similaridade igual ou superior a 70 % com as estirpes-tipo Azospirillum brasilense, A. amazonense, A. lipoferum, Herbaspirillum seropedicae e Burkholderia brasilensis. O resultado do comportamento dos isolados com base na tolerância à salinidade nem sempre foi semelhante ao obtido pelas características fenotípicas culturais a 70 % de similaridade, sendo indicado para estudos complementares de diversidade desses organismos. As BDNS apresentam potencial de utilização em estudos de avaliação da qualidade e sustentabilidade de ecossistemas. No entanto, apesar da alta densidade e diversidade fenotípica em solos da reserva, maiores valores foram obtidos no entorno, evidenciando o efeito positivo da cobertura vegetal do tipo gramíneas sobre elas, independentemente da variação climática.

  8. BACTÉRIAS DIAZOTRÓFICAS NÃO SIMBIÓTICAS E ENRAIZAMENTO DE ESTACAS SEMILENHOSAS DE OLIVEIRA (Olea europaea L.

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    Talita Filomena Silva

    2017-01-01

    Full Text Available Non-symbiotic diazotrophic bacteria (NSDB influence plant growth mainly through biological nitrogenfixation and production and release of plant growth-regulating substances. The effect of these bacteria on rooting of olive is not described in the international literature, which has been provided by the use of hormonal treatment based on indole butyric acid (IBA. The purpose of this study was to evaluate the physiological diversity of isolates obtained from soil samples of the Biological Reserve Serra dos Toledos, Itajubá, MG state, and of reference strains of NSDB, and their potential of substitution of IBA on rooting of olive semi-hardwood cuttings from the experimental farm ‘Maria da Fé’ (FEMF-EPAMIG. The isolates were divided into five groups (G1 to G5 according with cultural phenotypic characteristics based on color, diameter and consistence of colonies, and reference strains used were Azospirillum brasilense (BR11001 t , Azospirillum amazonense (BR11040 t , Herbaspirillum seropedicae (BR11175 t and Burkholderia brasilensis (BR11340 t . The diversity of physiological was performed using phosphate solubilization, tolerance to different conditions of temperature and pH and production of indole acetic acid (IAA. To evaluate the potential of semi-hardwood cuttings rooting in olive cultivars were used the cultivars Ascolano 315, Arbequina and Grappolo 541, from the germoplasm blank of the FEMF-EPAMIG. There were 33 treatments, and the cuttings were inoculated with the bacterial isolate groups, with the reference strains, without inoculation (control and only IBA, commercially used in rooting. Only two isolates showed ability to solubilize phosphate. Groups of isolates and of reference strains showed very similar environmental requirements, with wide ranges of optimum conditions of pH (5,0-9,0 and temperature (15-35ºC for maximum growth. The isolates and reference strains showed a production IAA ranging from 110.53 to 383.58 μg mL -1 , and

  9. Ecology of nitrogen fixation in soils and rhizospheres. Pt. 5

    Energy Technology Data Exchange (ETDEWEB)

    Werner, D.; Stripf, R.; Abramowski, R.; Fiedler, U.

    1980-12-01

    The effects of reduced oxygen concentration on root growth and activities of enzymes of N-metabolism of wheat (Triticum aestivum var. Kolibri) have been studied, for low O/sub 2/ tensions are required for N/sub 2/ fixation by microaerophilic bacteria (e.g. Azospirillum) associated with root systems of grasses. In hydrocultures with oxygen concentrations in the range of 0.2 to 1 mg O/sub 2/ x 1/sup -1/ compared to aerated cultures (8-9 mg O/sub 2/ x 1/sup -1/) root growth was reduced from 10 mg fresh weight x day/sup -1/ x plant/sup -1/ to one tenth 15 to 30 d after sowing. Specific activity of NADH and NADPH dependent glutamate dehydrogenase (E.C. 1.4.1.2 and 1.4.1.4) is reduced by 50% in the cultures with low oxygen concentrations 20 to 30 days after sowing, whereas specific activity of aspartate aminotransferase (E.C. 2.6.1.1) and alanine amino transferase (E.C. 2.6.1.2) is enhanced by a factor of two to three. Specific activity of glutamine synthetase is almost unaffected. Specific activity of glutamate dehydrogenase is lowest in the root tips, medium in young root hair zone and highest in the old root hair zone, glutamine synthetase activity is reverse in the three zones with differences by a factor of 3-5; aspartate aminotransferase is similarly active in the three zones. Nitrate concentration used (100 ..mu..M) for cultivation of the wheat plants was tested with Azospirillum brasilense in pure culture on agar surfaces exposed to air at the same pH (5.8), used for cultivation of the wheat plants. Activiy after a 14 day period (peak activity 70 mmol C/sub 2/H/sub 4/ x mg protein/sup -1/ x h/sup -1/) was not affected, however 1 mM and 5 mM nitrate added reduced the total activity to 50% and 10% respectively.

  10. Resposta de genótipos de trigo à inoculação de bactérias diazotróficas em condições de campo Wheat genotypes response to inoculation of diazotrophic bacteria in field conditions

    Directory of Open Access Journals (Sweden)

    Valéria Marino Rodrigues Sala

    2007-06-01

    Full Text Available O objetivo deste trabalho foi avaliar, em condições de campo, o efeito e a viabilidade econômica da inoculação de novos isolados homólogos de bactérias diazotróficas endofíticas, sob diferentes doses de nitrogênio, em dois genótipos de trigo, em duas localidades. Foram utilizados: três isolados de bactérias diazotróficas endofíticas (IAC-AT-8, Azospirillum brasilense; IAC-HT-11, Achromobacter insolitus; IAC-HT-12, Zoogloea ramigera, dois genótipos de trigo (ITD-19 e IAC-370 e três doses de N, na forma de uréia (0, 60 e 120 kg ha-1. No estádio de quatro folhas e no perfilhamento, foram avaliados a massa de matéria seca e o N acumulado na parte aérea. Na colheita, foram avaliados o teor de N, a massa de 1.000 sementes e a produtividade de grãos. A inoculação promoveu maior massa de matéria seca e N acumulado e aumentou a produtividade de grãos, principalmente na presença de adubo nitrogenado, com lucro para o agricultor. Entretanto, o maior aumento na produtividade de grãos foi obtido nas plantas do genótipo IAC-370, com o emprego do isolado IAC-HT-12, na ausência de N, que superou em 45% o tratamento testemunha. As respostas variaram em relação ao local de cultivo, o que sugere expressiva interação planta-bactéria-ambiente.The aim of this work was to evaluate, in field conditions, the effect and the economic viability of inoculation of new homologous strains endophytic diazotrophic bacteria, under different nitrogen doses on two wheat genotypes. Three strains of diazotrophic bacteria (IAC-AT-8, Azospirillum brasilense; IAC-HT-11, Achromobacter insolitus; IAC-HT-12, Zoogloea ramigera, two wheat genotypes (ITD-19 and IAC-370, and three levels of nitrogen fertilizer as urea (0, 60 e 120 kg ha-1 were tested. Shoot dry matter and total shoot nitrogen were evaluated, at four leaves and at tillering stages. Nitrogen concentration in the grain, 1,000 grains weight and yield were evaluated at harvest. Plants with

  11. Ocorrência de bactérias diazotróficas em diferentes genótipos de cana-de-açúcar Occurrence of diazotrophic bacteria in different sugar cane genotypes

    Directory of Open Access Journals (Sweden)

    FÁBIO BUENO DOS REIS JUNIOR

    2000-05-01

    Full Text Available O objetivo deste trabalho foi avaliar a localização e o número de bactérias endofíticas em quatro genótipos de cana-de-açúcar e investigar sobre a possível existência de correlação com os resultados apresentados em trabalhos de quantificação da fixação biológica de nitrogênio (FBN. Fez-se um levantamento das bactérias diazotróficas presentes, e quantificou-se a população de Herbaspirillum spp. e Acetobacter diazotrophicus, em genótipos de cana-de-açúcar contrastantes quanto à capacidade de obter N da FBN. De acordo com o levantamento realizado neste trabalho, as bactérias estudadas (Azospirillum lipoferum, A. brasilense, A. amazonense, Herbaspirillum spp. e Acetobacter diazotrophicus estavam presentes nos quatro genótipos avaliados e em todas as partes da planta, exceto A. amazonense, que não foi isolado de amostras de folhas. A quantificação das bactérias Herbaspirillum spp. e A. diazotrophicus mostrou não haver diferenças significativas entre os genótipos, e que, geralmente, elas estão presentes em maior número nas raízes. Enquanto Herbaspirillum spp. mantém-se mais estável ao longo do ciclo da cultura, a população de A. diazotrophicus decresce com a aproximação do final do ciclo comercial. Pode-se sugerir que as diferenças entre as taxas de FBN encontradas nos diversos genótipos não é causada por diferenças na presença ou no número das bactérias aqui estudadas.The objective of this work was to find out the localization and number of endophytic bacteria in four sugar cane genotypes and investigate upon the possible existence of correlation to the results obtained in some studies about quantification of biological nitrogen fixation (BNF. A survey of the diazotrophic bacteria present in sugar cane genotypes differing in their capacity to obtain nitrogen through BNF was performed, and population of Herbaspirillum spp. and Acetobacter diazotrophicus was quantified. The bacteria tested in the

  12. History on the biological nitrogen fixation research in graminaceous plants: special emphasis on the Brazilian experience

    Directory of Open Access Journals (Sweden)

    José I. Baldani

    2005-09-01

    Full Text Available This review covers the history on Biological Nitrogen Fixation (BNF in Graminaceous plants grown in Brazil, and describes research progress made over the last 40 years, most of whichwas coordinated by Johanna Döbereiner. One notable accomplishment during this period was the discovery of several nitrogen-fixing bacteria such as the rhizospheric (Beijerinckia fluminensis and Azotobacter paspali, associative (Azospirillum lipoferum, A. brasilense, A. amazonense and the endophytic (Herbaspirillum seropedicae, H. rubrisubalbicans, Gluconacetobacter diazotrophicus, Burkholderia brasilensis and B. tropica. The role of these diazotrophs in association with grasses, mainly with cereal plants, has been studied and a lot of progress has been achieved in the ecological, physiological, biochemical, and genetic aspects. The mechanisms of colonization and infection of the plant tissues are better understood, and the BNF contribution to the soil/plant system has been determined. Inoculation studies with diazotrophs showed that endophytic bacteria have a much higher BNF contribution potential than associative diazotrophs. In addition, it was found that the plant genotype influences the plant/bacteria association. Recent data suggest that more studies should be conducted on the endophytic association to strengthen the BNF potential. The ongoing genome sequencing programs: RIOGENE (Gluconacetobacter diazotrophicus and GENOPAR (Herbaspirillum seropedicae reflect the commitment to the BNF study in Brazil and should allow the country to continue in the forefront of research related to the BNF process in Graminaceous plants.A presente revisão aborda a história da Fixação Biológica de Nitrogênio (FBN em Gramíneas no Brasil, procurando mostrar a evolução da pesquisa na área iniciada a mais de 40 anos sob a liderança da pesquisadora Johanna Döbereiner. Um aspecto marcante deste período foi a descoberta de diversas bactérias fixadoras de nitrogênio atmosf

  13. Seleção de inoculantes à base de turfa contendo bactérias diazotróficas em duas variedades de arroz = Selection of peats inoculants with diazotrophic bacteria in two rice varieties

    Directory of Open Access Journals (Sweden)

    Vera Lúcia Divan Baldani

    2010-01-01

    Full Text Available O estudo consistiu em avaliar a sobrevivência e a eficiência das bactérias diazotróficas Herbaspirillum seropedicae, Burkholderia sp. e Azospirillum brasilense, inoculadas em dois tipos de turfas. A sobrevivência das bactérias foi determinada pelo método do NúmeroMais Provável (NMP, durante o armazenamento de até seis meses. A eficiência foi avaliada pela contribuição destas bactérias nos parâmetros agronômicos de acúmulo de massa seca e N-total dos grãos nas variedades de arroz IR42 e IAC4440. O experimento foi conduzido emvasos com solo, em delineamento inteiramente casualizado com três repetições, em arranjo fatorial 2 x 4. Os dados obtidos mostraram que o inoculante contendo a estirpe de Burkholderia sp. manteve o número de células viáveis em torno de 108 cel. g-1 de turfa no período testado, enquanto nos demais inoculantes este número ficou em torno de 106. Os ensaios de inoculação não mostraram diferenças significativas quanto à origem das turfas usadas como veículo sobre os parâmetros agronômicos e sobrevivência das bactérias. O tratamento que continha H. seropedicae manteve o acúmulo de massa seca e N-total dos grãos estatisticamente igual ao tratamento que recebeu 40 kg N ha-1, embora tenham sido observados aumentos de 13 e 19,4% nestes parâmetros na variedade IAC4440. Os resultados mostraram-se promissores quanto à utilização da prática de inoculação na cultura do arroz. The study consisted of a comparison of two-peat materials (Brazil and Canada containing different C-total content. The peats were inoculated with strains of Herbaspirillum seropedicae ZAE 94, Burkholderia sp. M130, and Azospirillum brasilense Sp109, and monitored during a period of six months in relation to variation on humidity and survival of bacteria in the inoculant. The quantification of viable cells in the inoculant was measured by the Most Probable Number (MPN method. The rice seeds were pelleted with the respective

  14. Restoration of eroded soil in the Sonoran Desert with native leguminous trees using plant growth-promoting microorganisms and limited amounts of compost and water.

    Science.gov (United States)

    Bashan, Yoav; Salazar, Bernardo G; Moreno, Manuel; Lopez, Blanca R; Linderman, Robert G

    2012-07-15

    Restoration of highly eroded desert land was attempted in the southern Sonoran Desert that had lost its natural capacity for self-revegetation. In six field experiments, the fields were planted with three native leguminous trees: mesquite amargo Prosopis articulata, and yellow and blue palo verde Parkinsonia microphylla and Parkinsonia florida. Restoration included inoculation with two of plant growth-promoting bacteria (PGPB; Azospirillum brasilense and Bacillus pumilus), native arbuscular mycorrhizal (AM) fungi, and small quantities of compost. Irrigation was applied, when necessary, to reach a rainy year (300 mm) of the area. The plots were maintained for 61 months. Survival of the trees was marginally affected by all supplements after 30 months, in the range of 60-90%. This variation depended on the plant species, where all young trees were established after 3 months. Plant density was a crucial variable and, in general, low plant density enhanced survival. High planting density was detrimental. Survival significantly declined in trees 61 months after planting. No general response of the trees to plant growth-promoting microorganisms and compost was found. Mesquite amargo and yellow palo verde responded well (height, number of branches, and diameter of the main stem) to inoculation with PGPB, AM fungi, and compost supplementation after three months of application. Fewer positive effects were recorded after 30 months. Blue palo verde did not respond to most treatments and had the lowest survival. Specific plant growth parameters were affected to varying degrees to inoculations or amendments, primarily depending on the tree species. Some combinations of tree/inoculant/amendment resulted in small negative effects or no response when measured after extended periods of time. Using native leguminous trees, this study demonstrated that restoration of severely eroded desert lands was possible. Copyright © 2012 Elsevier Ltd. All rights reserved.

  15. utilization of bio fertilizers and organic sources in arable soils under saline conditions using tracer technique

    International Nuclear Information System (INIS)

    Salama, O.A.E.

    2011-01-01

    Recently, more attention has been paid to conserve and save surrounding environment via minimizing the excessive use of chemical fertilizers and, in general, the agrochemicals applied in heavy quantities in agricultural agroecosystems. Therefore, the attention of most of agronomists was turned towards the use of so called clean agriculture or organic farming. Many of organic systems was pointed out such as the recycling of farm wastes i.e. crop residues, animal manure, organic conditioners for reclamation of soil and in the same time enhancement of plant growth and improving yield quality. The application of organic wastes combined with or without microbial inoculants to plant media are considered as a good management practice in any agricultural production system because it improves, plant quality and soil fertility. Therefore, we have the opportunity to conduct some experiments for achieving the clean agriculture approach, combating the adverse effects of salinity and avoiding the environmental pollution. Series of laboratory and greenhouse experiments were carried out to evaluate the impact of (1) potent isolated fungi (Aspergillus oryzae and Aspergillus terreus) on degrading plant residues (Leucaena and Acacia green parts), and (2) biofertilizers (Sinorhizobium meliloti, Azospirillum brasilense, and Pseudomonas aeruginosa) in assessing barley and spinach plants to combat salinity of soil and irrigation water. 15 N-tracer technique that considered unique and more reliable technique may benefits in clarifying the responsible mechanisms related to plant growth and gave us the opportunity to quantify the exact amounts of N derived from the different sources of nitrogen available to spinach and barley plants grown on sandy saline soil and irrigated with saline water.

  16. The effects of arbuscular mycorrhizal fungus and free living nitrogen fixing bacteria on growth, photosynthesis and yield of corn

    Directory of Open Access Journals (Sweden)

    mohsen jahan

    2009-06-01

    Full Text Available In recent years, biological fertilizers have received special attention by scientists in sustainable and low input agriculture. In order to study the effects of arbuscular mycorrhizal fungi and free living nitrogen fixing bacteria on growth and photosynthesis characteristics of corn in conventional and ecological cropping systems, a field experiment was conducted at the Research Farm of Ferdowsi University of Mashhad during year 2006. A split plots arrangement based on randomized complete block design with three replications was used. Treatments consisted four cropping systems (1- High input conventional system, 2- Medium input conventional system, 3- Low input conventional system and 4- Ecological system and four inoculations (1- Mycorrhiza fungus, Glomus intraradices, 2- Bacteria, Azotobacter paspali and Azospirillum brasilense, 3- Dual inoculation, Fungus plus bacteria, and 4- No-inoculation, control, which were allocated to main plots and sub plots, respectively. All agronomic practices and inputs application during planting and nursing for each of cropping systems were conducted according to regional traditions. Results showed that the effect of inoculation on photosynthesis rates of corn was significant, as the highest photosynthesis rate obtained in dual inoculation. Single inoculation (fungus or bacteria was ranked second. The effect of all inoculations on corn dry matter production was significant and dual inoculation produced the highest dry matter yield. The cropping systems have significant effect on corn yield and the difference between medium input conventional system and high input conventional system was significant, but the high input, low input and ecological cropping systems showed no differences. Inoculants affected the SPAD readings, and dual inoculation showed the highest SPAD readings. This study showed that utilization of low input conventional and ecological systems in combination with use of dual inoculation of

  17. Instrumental analysis of bacterial cells using vibrational and emission Moessbauer spectroscopic techniques

    International Nuclear Information System (INIS)

    Kamnev, Alexander A.; Tugarova, Anna V.; Antonyuk, Lyudmila P.; Tarantilis, Petros A.; Kulikov, Leonid A.; Perfiliev, Yurii D.; Polissiou, Moschos G.; Gardiner, Philip H.E.

    2006-01-01

    In biosciences and biotechnology, the expanding application of physicochemical approaches using modern instrumental techniques is an efficient strategy to obtain valuable and often unique information at the molecular level. In this work, we applied a combination of vibrational (Fourier transform infrared (FTIR), FT-Raman) spectroscopic techniques, useful in overall structural and compositional analysis of bacterial cells of the rhizobacterium Azospirillum brasilense, with 57 Co emission Moessbauer spectroscopy (EMS) used for sensitive monitoring of metal binding and further transformations in live bacterial cells. The information obtained, together with ICP-MS analyses for metals taken up by the bacteria, is useful in analysing the impact of the environmental conditions (heavy metal stress) on the bacterial metabolism and some differences in the heavy metal stress-induced behaviour of non-endophytic (Sp7) and facultatively endophytic (Sp245) strains. The results show that, while both strains Sp7 and Sp245 take up noticeable and comparable amounts of heavy metals from the medium (0.12 and 0.13 mg Co, 0.48 and 0.44 mg Cu or 4.2 and 2.1 mg Zn per gram of dry biomass, respectively, at a metal concentration of 0.2 mM in the medium), their metabolic responses differ essentially. Whereas for strain Sp7 the FTIR measurements showed significant accumulation of polyhydroxyalkanoates as storage materials involved in stress endurance, strain Sp245 did not show any major changes in cellular composition. Nevertheless, EMS measurements showed rapid binding of cobalt(II) by live bacterial cells (chemically similar to metal binding by dead bacteria) and its further transformation in the live cells within an hour

  18. Estimation of Nitrogenase Enzyme Activities and Plant Growth of Legume and Non-legume Inoculated with Diazotrophic Bacteria

    Directory of Open Access Journals (Sweden)

    Salwani S.

    2012-06-01

    Full Text Available Biological Nitrogen Fixation (BNF process benefits the agriculture sector especially for reducing cost of nitrogenfertilizer. In the process, the diazotrophs convert N2 into ammonia (NH3 which is useable by plants. The BNF process iscatalysed by nitrogenase enzyme that involved protons and electrons together with evolution of H2 therefore, theassessment of N2 fixation is also available via H2 production and electron allocation analysis. Thus, the aims of thisexperiment were to estimate the nitrogenase enzyme activities and observe the influence of diazothrophs on growth oflegume (soybean and non legume (rice plants. Host plants were inoculated with respective inocula; Bradyrhizobiumjaponicum (strain 532C for soybean while Azospirillum brasilense (Sp7 and locally isolated diazotroph (isolate 5 forrice. At harvest, the plants were observed for plant growth parameters, H2 evolution, N2 fixation and electron allocationcoefficient (EAC values. The experiment recorded N2 fixation activities of inoculated soybean plants at 141.2 μmol N2 h-1g-1 dry weight nodule, and the evolution of H2 at 144.4 μmol H2 h-1 g-1 dry weight nodule. The electron allocationcoefficient (EAC of soybean was recorded at 0.982. For inoculated rice plants, none of the observations was successfully recorded. However, results for chlorophyll contents and plant dry weight of both plants inoculated with respective inocula were similar to the control treatments supplied with full nitrogen fertilization (+N. The experiment clearly showed that inoculation of diazotrophic bacteria could enhance growth of the host plants similar to plants treated with nitrogenous fertilizer due to efficient N2 fixation process

  19. Microbial consortium role in processing liquid waste of vegetables in Keputran Market Surabaya as organic liquid fertilizer ferti-plus

    Science.gov (United States)

    Rizqi, Fauziah; Supriyanto, Agus; Lestari, Intan; Lita Indri D., L.; Elmi Irmayanti, A.; Rahmaniyah, Fadilatur

    2016-03-01

    Many activities in this market is directly proportional to increase production of vegetables waste, especially surabaya. Therefore, in this study aims to utilize liquid waste of vegetables into liquid organic fertilizer by mixing microbial consorsium. The microbial consorsium consist of Azotobacter chrococcum, Azospirillum brasilense, Rhizobium leguminosarum, Bacillus subtilis, Bacillus megaterium, Pseudomonas putida, and Pseudomonas fluorescens. Ttreatment of microbial concentrations (5%, 10%, 15%) and the length of the incubation period (7 days, 14 days, 21 days) used in this research. The parameters used are: C/N ratio, levels of CNP, and BOD value. This study uses a standard organic fertilizer value according SNI19-7030-2004, The results show the value of C/N ratio comply with the ISO standards. C levels showed an increase during the incubation period but not compare with standards. N levels that compare with standards are microbial treatment in all group concentration except control group with an incubation period of 21 days is > 7. P levels compare with the existing standards in the group of microbe concentration of 10% and 15% during the incubation period. The value of the initial BOD liquid waste of vegetable is 790.25 mg / L, this value indicates that the waste should not go into the water body. Accordingly, the results of this study can not be used as a liquid organic fertilizer, but potentially if it is used as a natural career or build natural soil. The Building natural soil is defined as the natural ingredients that can be used to improve soil properties.

  20. Instrumental analysis of bacterial cells using vibrational and emission Moessbauer spectroscopic techniques

    Energy Technology Data Exchange (ETDEWEB)

    Kamnev, Alexander A. [Laboratory of Biochemistry of Plant-Bacterial Symbioses, Institute of Biochemistry and Physiology of Plants and Microorganisms, Russian Academy of Sciences, 410049 Saratov (Russian Federation)]. E-mail: aakamnev@ibppm.sgu.ru; Tugarova, Anna V. [Laboratory of Biochemistry of Plant-Bacterial Symbioses, Institute of Biochemistry and Physiology of Plants and Microorganisms, Russian Academy of Sciences, 410049 Saratov (Russian Federation); Antonyuk, Lyudmila P. [Laboratory of Biochemistry of Plant-Bacterial Symbioses, Institute of Biochemistry and Physiology of Plants and Microorganisms, Russian Academy of Sciences, 410049 Saratov (Russian Federation); Tarantilis, Petros A. [Laboratory of Chemistry, Department of Science, Agricultural University of Athens, 11855 Athens (Greece); Kulikov, Leonid A. [Laboratory of Nuclear Chemistry Techniques, Department of Radiochemistry, Faculty of Chemistry, M.V. Lomonosov Moscow State University, 119992 Moscow (Russian Federation); Perfiliev, Yurii D. [Laboratory of Nuclear Chemistry Techniques, Department of Radiochemistry, Faculty of Chemistry, M.V. Lomonosov Moscow State University, 119992 Moscow (Russian Federation); Polissiou, Moschos G. [Laboratory of Chemistry, Department of Science, Agricultural University of Athens, 11855 Athens (Greece); Gardiner, Philip H.E. [Division of Chemistry, School of Science and Mathematics, Sheffield Hallam University, Sheffield S1 1WB (United Kingdom)

    2006-07-28

    In biosciences and biotechnology, the expanding application of physicochemical approaches using modern instrumental techniques is an efficient strategy to obtain valuable and often unique information at the molecular level. In this work, we applied a combination of vibrational (Fourier transform infrared (FTIR), FT-Raman) spectroscopic techniques, useful in overall structural and compositional analysis of bacterial cells of the rhizobacterium Azospirillum brasilense, with {sup 57}Co emission Moessbauer spectroscopy (EMS) used for sensitive monitoring of metal binding and further transformations in live bacterial cells. The information obtained, together with ICP-MS analyses for metals taken up by the bacteria, is useful in analysing the impact of the environmental conditions (heavy metal stress) on the bacterial metabolism and some differences in the heavy metal stress-induced behaviour of non-endophytic (Sp7) and facultatively endophytic (Sp245) strains. The results show that, while both strains Sp7 and Sp245 take up noticeable and comparable amounts of heavy metals from the medium (0.12 and 0.13 mg Co, 0.48 and 0.44 mg Cu or 4.2 and 2.1 mg Zn per gram of dry biomass, respectively, at a metal concentration of 0.2 mM in the medium), their metabolic responses differ essentially. Whereas for strain Sp7 the FTIR measurements showed significant accumulation of polyhydroxyalkanoates as storage materials involved in stress endurance, strain Sp245 did not show any major changes in cellular composition. Nevertheless, EMS measurements showed rapid binding of cobalt(II) by live bacterial cells (chemically similar to metal binding by dead bacteria) and its further transformation in the live cells within an hour.

  1. TRATAMIENTOS POST-COSECHA DE LA SEMILLA DE PAPAYO PARA MEJORAR LA GERMINACIÓN Y DESARROLLO DE LA PLÁNTULA

    Directory of Open Access Journals (Sweden)

    Guillermo M. Carrillo

    2013-04-01

    Full Text Available Tecnologías prácticas se requieren para preservar la viabilidad de las semillas en particular cuando su viabilidad no es duradera como la semilla de Carica papaya (papaya. Semillas de papaya fueron embebidas en agua o en soluciones de CaCl2 10-5 M, ácido salicílico 10-4 M y ácido giberélico 10-5 M e inoculadas con una suspensión de células bacterianas para determinar sus efectos en la germinación, desarrollo inicial de las plántulas, acumulación de biomasa y de clorofila. Las semillas embebidas en agua germinaron 40 % más y requirieron de dos días menos para que el 50 % de la semilla germinara en comparación con la semilla sin tratar; sin embargo, la semilla sin tratar generó plántulas de mayor longitud (9.2 cm y más vigorosas. La semilla embebida en la solución combinada de calcio, ácido giberélico y ácido salicílico generó plántulas de mayor peso (biomasa fresca y seca superando al control. La semilla embebida en solución de ácido giberélico seguido de la inoculación con células de Azospirillum brasilense tuvieron alta germinación (69 %, emergencia (47 % y generaron plántulas de mayor altura, 19 % más que el testigo. Las diferencias en la acumulación de clorofila fueron mínimas.

  2. Identification and Quantification of Cause and Effects in Symbiosis of Corn with Arbuscular Mycorrehiza Fungus using Structural Equation Modeling Approach

    Directory of Open Access Journals (Sweden)

    M Jahan

    2015-09-01

    Full Text Available Considering to necessity and importance of determining mycorrhizal symbiosis level and its effects on crop agroecological characteristics as well as other related factors affecting this relationship, beside, the lack of an assured method for this purpose, the present study designed based on new perspectives and insights for determining cause and effects relations, latent variables using structural equation modeling (SEM approach. A field experiment was conducted during 2 years. A split plots arrangement based on randomized complete block design (RCBD with three replications was used. Treatments consisted four cropping systems (high, medium, and low input conventional as well as ecological system and four inoculations (mycorrhizae fungus: Glomus intraradices, plant growth promoting rhizobacteria (PGPR: (Azospirillum brasilense, Azotobacter paspali, dual inoculation: (fungus plus bacteria, and no-inoculation (control, which were allocated to main plots and sub plots, respectively. At the first step, a confirmatory factor analyzing was conducted resulted to two distinguished factors, and then the variables which had the most loads (weight on one of these two factors were determined. At the second step, considering ecophysiological basis of crops growth and development, in order to continue analyzing, the first factor (including: leaf area index (LAI, root length colonization percent (RLCP, dry matter (DM, stem diameter (D, SPAD readings and the second factor (including: maximum photosynthesis (Amax, specific root length (SRL, canopy temperature (CT, plant height (H, soil respiration rate (SRR, variable chlorophyll fluorescence to maximum chlorophyll fluorescence (Fv/Fm, plant tissue phosphorus content (%P determined resource capture latent construct and resource utilization latent construct, respectively. Correlation coefficients, squared multiple correlation coefficients, covariance matrices, direct and indirect path coefficients were calculated

  3. Isolation and identification of phosphate solubilizer Azospirillum, Bacillus and Enterobacter strains by 16SrRNA sequence analysis and their effect on growth of wheat (Triticum aestivum L.)

    NARCIS (Netherlands)

    Tahir, M.; Mirza, M.S.; Zaheer, A.; Rocha Dimitrov, M.; Smidt, H.; Hameed, S.

    2013-01-01

    The aim of the present study was to isolate phosphate solubilizing bacteria from wheat rhizosphere and investigate their potential for plant growth promotion. Three phosphate solubilizing bacterial strains were isolated by serial dilution method from the rhizosphere of wheat grown under wheat-cotton

  4. Effect of Biofertilizers and Irrigation Intervals on Yield Component and Yield of Fenugreek (Trigonella foenum- graecum L.

    Directory of Open Access Journals (Sweden)

    M. Jaberi

    2016-02-01

    , Azad University, Birjand, Iran, during 2010-2011. Experimental treatments were irrigation intervals in three levels (every 6, 9 and 12 days and biofertilizer in five levels (nitroxin, biophosphorus, and micorhyza fungi G. mosseae, G. intraradices and control-no fertilizer. Fenugreek was planted through furrow in mid-April 2010. The distance between rows and between plants was 30 and 10 cm, respectively. Seeds were covered by Nitroxin (including: Azotobacterchroococcum, Azospirillum lipoferum and Azospirillum brasilense and biophosphrous (including: Pseudomonas fluorescens and then were cultured.They were used at a depth of 2cm below the seed from Glomusintraradiceand Glomus mosseae. Fenugreek was harvested in early July when the plants became yellow and at least 80% of the pods were reached. Statistical analysis of the data was performed using SAS 9.1 and MSTATC. Mean comparison were compared by the Duncan test at 1% and 5% level of probability. Results and Discussion: Results of statistical analysis showed that irrigation treatments and biofertilizers had significant effect on most indices. Interaction effect of irrigation and biofertilizer were significant on seed and leaf yield (p

  5. THE RESURRECTION PLANT TRIPOGON SPICATUS (POACEAE HARBORS A DIVERSITY OF PLANT GROWTH PROMOTING BACTERIA IN NORTHEASTERN BRAZILIAN CAATINGA

    Directory of Open Access Journals (Sweden)

    Paulo Ivan Fernandes-Júnior

    2015-08-01

    reference strainAzospirillum brasilense, Ab-V5. The results indicate the potential of T. spicatus as native plant source of plant growth promoting bacteria.

  6. A disposable laser print-cut-laminate polyester microchip for multiplexed PCR via infra-red-mediated thermal control

    International Nuclear Information System (INIS)

    Ouyang, Yiwen; Duarte, Gabriela R.M.; Poe, Brian L.; Riehl, Paul S.; Santos, Fernando M. dos; Martin-Didonet, Claudia C.G.; Carrilho, Emanuel; Landers, James P.

    2015-01-01

    Infrared (IR)-mediated thermal cycling system, a method proven to be a effective for sub-μL scale polymerase chain reaction (PCR) on microchips, has been integrated with DNA extraction and separation on a glass microchip in a fully integrated micro Total Analysis System by Easley et al., in 2006. IR-PCR has been demonstrated on both glass and PMMA microdevices where the fabrication (bonding) is not trivial. Polyester-toner (PeT) microfluidic devices have significant potential as cost-effective, disposable microdevices as a result of the ease of fabrication (∼$0.25 USD and <10 min per device) and availability of commercial substrates. For the first time, we demonstrate here the thermal cycling in PeT microchips on the IR-PCR system. Undesirable IR absorption by the black-toner bonding layer was eliminated with a spatial filter in the form of an aluminum foil mask. The solution heating rate for a black PeT microchip using a tungsten lamp was 10.1 ± 0.7 °C s −1 with a cooling rate of roughly −12 ± 0.9 °C s −1 assisted by forced air cooling. Dynamic surface passivation strategies allowed the successful amplification of a 520 bp fragment of the λ-phage genome (in 11 min) and a 1500 bp region of Azospirillum brasilense. Using a centrosymmetric chamber configuration in a multichamber PeT microchip, homogenous temperature distribution over all chambers was achieved with inter-chamber temperature differences at annealing, extension and denaturing steps of less than ±2 °C. The effectiveness of the multichamber system was demonstrated with the simultaneous amplification of a 390 bp amplicon of human β-globin gene in five PeT PCR microchambers. The relative PCR amplification efficiency with a human β-globin DNA fragment ranged from 70% to 90%, in comparison to conventional thermal cyclers, with an inter-chamber standard deviation of ∼10%. Development of PeT microchips for IR-PCR has the potential to provide rapid, low-volume amplification

  7. Co-inoculation effects of Bradyrhizobium japonicum and ...

    African Journals Online (AJOL)

    Co-inoculation effects of Bradyrhizobium japonicum and Azospirillum sp. on competitive nodulation and rhizosphere eubacterial community structures of soybean under rhizobia-established soil conditions.

  8. Groundwater Chemistry and Microbial Ecology Effects on Explosives Biodegradation

    Science.gov (United States)

    2008-09-01

    hexahydro-1,3,5-trinitro-1,3,5-triazine catalyzed by a 17 NAD(P)H: nitrate oxidoreductase from Aspergillus niger. Environ Sci Technol 18 36:3104-3108. 19...Azospirillum sp. B518 [AB049112] RDX clone 8 [EU907872] RDX clone 2 [EU907866] Azospirillum sp. 2436 [EF422176] Pleomorphomonas oryzae F-4

  9. A disposable laser print-cut-laminate polyester microchip for multiplexed PCR via infra-red-mediated thermal control

    Energy Technology Data Exchange (ETDEWEB)

    Ouyang, Yiwen [Department of Chemistry, University of Virginia, Charlottesville, VA 22904 (United States); Duarte, Gabriela R.M. [Department of Chemistry, University of Virginia, Charlottesville, VA 22904 (United States); Universidade Federal de Goiás, Goiânia, GO 74690-900 (Brazil); Poe, Brian L.; Riehl, Paul S. [Department of Chemistry, University of Virginia, Charlottesville, VA 22904 (United States); Santos, Fernando M. dos; Martin-Didonet, Claudia C.G. [Universidade Estadual de Goiás, Anápolis, GO 75132-400 (Brazil); Carrilho, Emanuel [Instituto de Química de São Carlos, Universidade de São Paulo, São Carlos, SP 13566-590 (Brazil); Instituto Nacional de Ciência e Tecnologia de Bioanalítica, CP 6154, Campinas, SP 13083-970 (Brazil); Landers, James P., E-mail: landers@virginia.edu [Department of Chemistry, University of Virginia, Charlottesville, VA 22904 (United States); Department of Mechanical Engineering, University of Virginia, Charlottesville, VA 22904 (United States); Department of Pathology, University of Virginia Health Science Center, Charlottesville, VA (United States)

    2015-12-11

    Infrared (IR)-mediated thermal cycling system, a method proven to be a effective for sub-μL scale polymerase chain reaction (PCR) on microchips, has been integrated with DNA extraction and separation on a glass microchip in a fully integrated micro Total Analysis System by Easley et al., in 2006. IR-PCR has been demonstrated on both glass and PMMA microdevices where the fabrication (bonding) is not trivial. Polyester-toner (PeT) microfluidic devices have significant potential as cost-effective, disposable microdevices as a result of the ease of fabrication (∼$0.25 USD and <10 min per device) and availability of commercial substrates. For the first time, we demonstrate here the thermal cycling in PeT microchips on the IR-PCR system. Undesirable IR absorption by the black-toner bonding layer was eliminated with a spatial filter in the form of an aluminum foil mask. The solution heating rate for a black PeT microchip using a tungsten lamp was 10.1 ± 0.7 °C s{sup −1} with a cooling rate of roughly −12 ± 0.9 °C s{sup −1} assisted by forced air cooling. Dynamic surface passivation strategies allowed the successful amplification of a 520 bp fragment of the λ-phage genome (in 11 min) and a 1500 bp region of Azospirillum brasilense. Using a centrosymmetric chamber configuration in a multichamber PeT microchip, homogenous temperature distribution over all chambers was achieved with inter-chamber temperature differences at annealing, extension and denaturing steps of less than ±2 °C. The effectiveness of the multichamber system was demonstrated with the simultaneous amplification of a 390 bp amplicon of human β-globin gene in five PeT PCR microchambers. The relative PCR amplification efficiency with a human β-globin DNA fragment ranged from 70% to 90%, in comparison to conventional thermal cyclers, with an inter-chamber standard deviation of ∼10%. Development of PeT microchips for IR-PCR has the potential to provide rapid, low

  10. Response of Sunflower (Helianthus annuus L.) to N-application and Bio fertilization with Assessment of Fertilizer N Recovery by 15N Versus Subtraction Methods

    International Nuclear Information System (INIS)

    Abdel-Salam, A. A.; Zahra, W.R.; Soliman, S. M.; Galal, Y.G.M.; Moursy, A.A.; Hekal, M.A.

    2015-01-01

    A factorial field experiment was conducted on sunflower (Helianthus annuus L.) grown on a sand soil (98% sand) supplied the different combinations of 4 N rates of 0, 105, 140 and 175 kg N ha -1 i.e. N 0 , N 1 , N 2 , and N 3 respectively - as (NH 4 ) 2 SO 4 and 4 bio fertilization inoculation (B) of none, Azotobacter chroococcum, Azospirillum brasilense and Bacillus megaterium. i.e. B 0 ,B 1 ,B 2 , and B 3 respectively. Labeled ammonium sulphate with 2% 15 N atom excess was used for 15 N assessment. All plots were supplied with 21 Mg compost +24 kg P +80 kg K ha - '1. Non-treated plants gave 0.534 Mg seeds ha -1 while the treated ones - especially those of N or N + bio fertilizers - gave increases of up to 403% (N 2 B). Main effect response patterns were: N: N 3 >N 2 >N 1 , for B: B 1 ≥B 3 ≥B 2 . Seed oil content in the N 0 B 0 treatment was 222 gkg -1 increased reaching as high as 445 gkg -1 by N 2 B 3 ; with N main effect of N 2 >N 3 >N 1 and B main effect of B 2 >B 3 >B 1 . Seed oil yield was 113 kg ha -1 by N 0 B 0 increased to as high as 1105 kg ha -1 by N 2 B 1 with main effects of N 2 >N 3 >N 1 and B 3 ≥B 2 >B 1 .Uptake of N (in total plant parts of roots + stems + leaves + discs + seeds) increased by N application; averages for non-N were 18.1 kg ha -1 18.5,14.7,17.4 by N 0 B 0 , N 0 B 1 , N 0 B 2 , and N 0 B 3 respectively; increased considerably by up to 667% (N 3 B 3 ) upon N application. Plants recovered a portion of fertilizer N of 19.6 to 40.9% by N 1 B 1 and N 2 B 1 respectively as determined by 15 N technique, but 27.7 to 59.6% respectively as calculated by subtraction of non-N from N treatments. The subtraction estimation considerably exceeded the 15 N determined ones by + 39.5% to as high as + 194.6% indicating a non-real estimation of recovered fertilizer-N in crops. Thus, in studies using non-tracer techniques, estimation of uptake of fertilizer N could be erroneous. The reason in the current study could most certainly be a greater

  11. Estimation of the efficiency of hydrocarbon mineralization in soil by measuring CO2-emission and variations in the isotope composition of carbon dioxide

    Science.gov (United States)

    Dubrovskaya, Ekaterina; Turkovskaya, Olga

    2010-05-01

    Estimation of the efficiency of hydrocarbon mineralization in soil by measuring CO2-emission and variations in the isotope composition of carbon dioxide E. Dubrovskaya1, O. Turkovskaya1, A. Tiunov2, N. Pozdnyakova1, A. Muratova1 1 - Institute of Biochemistry and Physiology of Plants and Microorganisms, RAS, Saratov, 2 - A.N. Severtsov Institute of Ecology and Evolution, RAS, Moscow, Russian Federation Hydrocarbon mineralization in soil undergoing phytoremediation was investigated in a laboratory experiment by estimating the variation in the 13С/12С ratio in the respired СО2. Hexadecane (HD) was used as a model hydrocarbon pollutant. The polluted soil was planted with winter rye (Secale cereale) inoculated with Azospirillum brasilense strain SR80, which combines the abilities to promote plant growth and to degrade oil hydrocarbon. Each vegetated treatment was accompanied with a corresponding nonvegetated one, and uncontaminated treatments were used as controls. Emission of carbon dioxide, its isotopic composition, and the residual concentration of HD in the soil were examined after two and four weeks. At the beginning of the experiment, the CO2-emission level was higher in the uncontaminated than in the contaminated soil. After two weeks, the quantity of emitted carbon dioxide decreased by about three times and did not change significantly in all uncontaminated treatments. The presence of HD in the soil initially increased CO2 emission, but later the respiration was reduced. During the first two weeks, nonvegetated soil had the highest CO2-emission level. Subsequently, the maximum increase in respiration was recorded in the vegetated contaminated treatments. The isotope composition of plant material determines the isotope composition of soil. The soil used in our experiment had an isotopic signature typical of soils formed by C3 plants (δ13C,-22.4‰). Generally, there was no significant fractionation of the carbon isotopes of the substrates metabolized by the

  12. Search Results | Page 36 | IDRC - International Development ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Results 351 - 360 of 1327 ... Global epidemiology of clonorchiasis and its relation with cholangiocarcinoma ... ECONOMIC CONDITIONS INDIA ETHNIC CONFLICTS YOUTH RELIGIOUS DISCRIMINATION ... Enabling poverty relevance of Azospirillum bio-innovation : lessons from eco-enterprises in Tamil Nadu, India.

  13. Comparative study of the fungicide Benomyl toxicity on some plant growth promoting bacteria and some fungi in pure cultures

    Directory of Open Access Journals (Sweden)

    Elslahi Randa H.

    2014-03-01

    Full Text Available Six laboratory experiments were carried out to investigate the effect of the fungicide Benomyl on pure cultures of some plant growth promoting bacteria (PGPB and some fungi. The highest LD50 was recorded for Bacillus circulans and proved to be the most resistant to the fungicide, followed by Azospirillum braziliense, while Penicillium sp. was the most affected microorganism. LD50 values for the affected microorganisms were in 21-240 orders of magnitude lower in comparison with the LD50 value for Azospirillum braziliense. The results indicate a strong selectivity for Benomyl against Rhizobium meliloti and Penicillium sp. when compared to other microorganisms tested. The highest safety coefficient was recorded for Bacillus circulans followed by Azospirillum braziliense, while Rhizobium meliloti, showed the lowest safety coefficient value compared to other bacteria. The lowest toxicity index was recorded for Bacillus circulans and Azospirillum braziliense. The slope of the curves for Bacillus sp. and Rhizobium meliloti was steeper than that of the other curves, suggesting that even a slight increase of the dose of the fungicide can cause a very strong negative effect. In conclusion, Benomyl could be applied without restriction when using inocula based on growth promoting bacteria such as symbiotic nitrogen fixers (Rhizobium meliloti, non-symbiotic nitrogen fixers (Azospirillum braziliense or potassium solibilizers (Bacillus circulans, given that the fungicide is applied within the range of the recommended field dose.

  14. Molecular and physiological responses of sunflower (helianthus annuus l.) to pgpr and sa under salt stress

    International Nuclear Information System (INIS)

    Naz, R.

    2015-01-01

    This paper presents the efficacy of PGPR (Azospirillum and Pseudomonas) and its modulation by salicylic acid. Two hybrids of sunflower (Hysun and Parsun) were inoculated with Azospirillum spp. and Pseudomonas spp. prior to sowing. Salt stress (20 dSm-1) was applied 28 d after sowing followed by foliar spray of salicylic acid (100 micro M) after 4 h of salt treatment. Azospirillum and Pseudomonas inoculation alone and in combination with salicylic acid alleviated the effects of salt stress on both the sunflower hybrids. The salt tolerance in these treatments was mediated by an increase in relative water content, carotenoids, proline, ABA, induction of new polypeptide bands and yield of sunflower hybrids. In response to salt stress four new polypeptide bands were synthesized in both Hysun, whereas, a group of six polypeptide bands were observed in Parsun. Application of salicylic acid alone and in combination with Azospirillum found to induce four new polypeptide bands in Hysun and Parsun. It is inferred that synthesis of new proteins in response to the combined application of salicylic acid and Azospirillum under salt stress, may play an important role as stress proteins in tolerance of sunflower hybrids to salt stress. (author)

  15. Comparative study of the fungicide Benomyl toxicity on some plant growth promoting bacteria and some fungi in pure cultures.

    Science.gov (United States)

    Elslahi, Randa H; Osman, Awad G; Sherif, Ashraf M; Elhussein, Adil A

    2014-03-01

    Six laboratory experiments were carried out to investigate the effect of the fungicide Benomyl on pure cultures of some plant growth promoting bacteria (PGPB) and some fungi. The highest LD50 was recorded for Bacillus circulans and proved to be the most resistant to the fungicide, followed by Azospirillum braziliense, while Penicillium sp. was the most affected microorganism. LD50 values for the affected microorganisms were in 21-240 orders of magnitude lower in comparison with the LD50 value for Azospirillum braziliense. The results indicate a strong selectivity for Benomyl against Rhizobium meliloti and Penicillium sp. when compared to other microorganisms tested. The highest safety coefficient was recorded for Bacillus circulans followed by Azospirillum braziliense, while Rhizobium meliloti, showed the lowest safety coefficient value compared to other bacteria. The lowest toxicity index was recorded for Bacillus circulans and Azospirillum braziliense. The slope of the curves for Bacillus sp. and Rhizobium meliloti was steeper than that of the other curves, suggesting that even a slight increase of the dose of the fungicide can cause a very strong negative effect. In conclusion, Benomyl could be applied without restriction when using inocula based on growth promoting bacteria such as symbiotic nitrogen fixers (Rhizobium meliloti), non-symbiotic nitrogen fixers (Azospirillum braziliense) or potassium solibilizers (Bacillus circulans), given that the fungicide is applied within the range of the recommended field dose.

  16. Effects of Vermi-compost and Two Bacterial Bio-fertilizers on some Quality Parameters of Petunia

    Directory of Open Access Journals (Sweden)

    Mina Zarghami MOGHADAM

    2013-05-01

    Full Text Available The present research was conducted to study the effect of vermi-compost and two bio-fertilizer applications on growth, yield and quality of petunia (Petunia hybrida. The experiment laid out in randomized block design with 3 replications and 9 treatment combinations composing of vermi-compost, bio-fertilizers and NPK fertilizer. The treatment receiving Azospirillum sp. + Phosphate solubilizing bacterium + Vermicompost + NPK (25% of recommended dose recorded the highest plant height, number of branches, plant spread, leaf area index, dry matter accumulation and yield attributes such as number of flowers per plant, number of flowers per plot, flower yield/plant, flower yield/plot. The early flower bud initiation, 50 percent flowering and more flowering duration was achieved in the treatment receiving Azospirillum sp. + Phosphate solubilizing bacterium + Vermicompost + NPK (25% of recommended dose. Application of Azospirillum sp. + Phosphate solubilizing bacterium + Vermicompost + NPK (25% of recommended dose registered significantly higher quality parameters such as flower diameter.

  17. Bio-remediation of Pb and Cd polluted soils by switchgrass: A case study in India.

    Science.gov (United States)

    Arora, Kalpana; Sharma, Satyawati; Monti, Andrea

    2016-01-01

    In the present study bioremediation potential of a high biomass yielding grass, Panicum virgatum (switchgrass), along with plant associated microbes (AM fungi and Azospirillum), was tested against lead and cadmium in pot trials. A pot trial was set up in order to evaluate bioremediation efficiency of P. virgatum in association with PAMs (Plant Associated Microbes). Growth parameters and bioremediation potential of endomycorrhizal fungi (AMF) and Azospirillum against different concentrations of Pb and Cd were compared. AM fungi and Azospirillum increased the root length, branches, surface area, and root and shoot biomass. The soil pH was found towards neutral with AMF and Azospirillum inoculations. The bioconcentration factor (BCF) for Pb (12 mg kg(-1)) and Cd (10 mg kg(-1)) were found to be 0.25 and 0.23 respectively and translocation index (Ti) was 17.8 and 16.7 respectively (approx 45% higher than control). The lower values of BCF and Ti, even at highest concentration of Pb and Cd, revealed the capability of switchgrass of accumulating high concentration of Pb and Cd in the roots, while preventing the translocation of Pb and Cd to aerial biomass.

  18. 1373-IJBCS-Article-Lamine Said Babamoussa

    African Journals Online (AJOL)

    KODJIO NORBERT

    Les rhizobactéries Pseudomonas fluorescens ont induit le rendement de maïs le plus élevé, dépassant de ... Bacillus licheniformis, Bacillus lentus, Bacillus circulans, Bacillus firmus et Azospirillum ..... asiciadas al cultivo del maiz. ... bacteria and their inoculation effects on growth and nitrogen uptake of crop plants. J.

  19. Cellular and molecular-genetic mechanisms of symbiosis and associative interaction of microorganisms with plants in rhizosphere

    Directory of Open Access Journals (Sweden)

    Lioshina L. G.

    2009-02-01

    Full Text Available The review contains the results of research on symbiotic and associative interaction of microorganisms and plants in rhizosphere. A special attention is given to the process of contact association of microorganisms and plants tissues including the concrete molecular structures and dominant role pertaining to protein-carbohydrate interaction. There are common features and distinctions at formation of arbuscular mycorhiza, rhizobia– legume symbiosis and association of non-leguminous plants with Azospirillum

  20. Influence of levels of nitrogen and management on seed cotton yield and 15N recovery by cotton

    International Nuclear Information System (INIS)

    Arulmozhiselvan, K.; Govindaswamy, M.

    1999-01-01

    Cotton var.MCU.5 showed varied response to N levels under different management practices. Higher yields were associated at 60-80 kg N ha -1 under combined application of urea, FYM and azospirillum. Whereas urea alone registered higher yield at 100-120 kg N ha -1 , high 15 N recovery (35.84%) was found to be associated with urea + FYM combination. (author)

  1. Effect of Plant Growth Promoting Rhizobacteria (PGPR on Phenological Traits, Grain Yield and Yield Components of Three Maize (Zea mays L. Cultivars

    Directory of Open Access Journals (Sweden)

    A Soleimani Fard

    2013-11-01

    Full Text Available To evaluate the effect of bio-fertilize on yield and its components in maize cultivars, an split plot experiment based on randomized complete bock design with three replications in was conducted in Payam-noor University of Ilam, Iran, in 2009-2010. Treatments were cultivar (SC604, SC704 and SC807 assigned to main plots and bio-fertilizer (non- inoculation, inoculation with Azetobacter, Azospirillum and dual inoculation ofAzotobacterand Azospirillum to subplots. The effect of cultivar on days to maturity, plant height, dry matter, ear length, stem diameter, number of grain per ear row, 1000-grain weight, grain yield, biological yield and protein content was significant cultivar. SC 704 had the highest dry matter (259.5 g.m-2, plant height (201.1 cm, number of grain per ear row (42.8 grain, grain yield (10850 kg.m-2, and biological yield (22040 kg.m-2. The effect of plant growth promoting rhizobacteria on all traits expect harvest index was significant. Dual inoculation ofAzotobacterand Azospirillum had the longest days to ear initiation (71.2 days, days to maturity (115.4 day, number of leaves above ear (5.6 ear, dry matter (240.4 g.m-2, ear length (24.3 cm, plant height (212.4 cm, seed number of rows per ear (14.5 row, number of grains per row (44.2 grain, grain yield (10190 kg.m-2, biological yield (21320 kg.m-2 and protein content (10.7%. Interaction effect of cultivar× plant growth promoting rhizobacteria on grain yield was significant. The highest and lowest grain yield was obtained from SC 704 and application of dual inoculation ofAzotobacterand Azospirillum (12320 kg.ha-1 and lowest from SC 604 when inoculation treatments were not used 7570 kg.ha-1 respectively.

  2. The Effectiveness of Biofertilizer on Plant Growth Soyb Ea N “Edam Am E” (Glycin Max)

    OpenAIRE

    Sudiarti, Diah

    2017-01-01

    This study aimed at determining the effectiveness of biofertilizer with different concentrations on plant growth of soybean “edamame” (glycin max). Biofertilizer in this study consists of microbial consortia (lactobacillus, pseudomonas, bacillus, saccharomyces, rhizobium, azotobacter, azospirillum, and cellulomonas). The treatment consists of 3 biofertilizer concentrations (25%, 50%, dan 75%), as well as the negative control and positive control (100% chemical fertilizer equivalent 5g/plant)....

  3. Microorganismos benéficos como biofertilizantes eficientes para el cultivo del tomate (Lycopersicon esculentum, Mill Beneficial microorganisms as efficient biofertilisers for tomato crops (Lycopersicon esculentum, Mill

    Directory of Open Access Journals (Sweden)

    Hernández Annia

    2005-12-01

    Full Text Available En el uso y manejo de biofertilizantes en la agricultura, uno de los principales problemas es el desconocimiento de las especies presentes en los agroecosistemas y en la rizosfera de los cultivos, para su posible utilización eficiente. Desde el punto de vista ecológico, es importante conocer los integrantes de la comunidad bacteriana que favorecen su aplicación como inoculantes y propician un efecto agrobiológico positivo en los cultivos agrícolas. Esta investigación se desarrolló con el objetivo de evaluar la efectividad agrobiológica de Azospirillum sp, en el crecimiento, desarrollo y rendimiento en el cultivo del tomate. Para ello, se partió de seleccionar el género microbiano predominante en la rizosfera del cultivo y posteriormente se evaluó el efecto de su inoculación a partir de la respuesta del cultivo. Los resultados demostraron que los géneros Pseudomonas, Azospirillum, Azotobacter, Bacillus y Streptomyces, forman parte de la comunidad microbiana de la rizosfera del tomate, en las condiciones estudiadas, y que Azospirillum es el género dominante. La inoculación artificial de esta rizobacteria causó un efecto positivo sobre el crecimiento de las plántulas, así como en el estado nutricional de las plantas, con un rendimiento agrícola superior a un 11 % con respecto a las plantas testigo. Se obtuvo un alto nivel poblacional en la rizosfera de las plantas inoculadas. Palabras clave: rizosfera, inoculante, crecimiento, rendimiento.One of the main problems regarding the efficient use and management of biofertilizers in agriculture lies in the unknown species present in agro-ecosystems and crop rhizospheres. From the ecological point of view, it is important to know the members of the bacterial population allowing them to be applied as inoculants and enable a positive agro-biological effect on agricultural crops. This investigation was aimed at evaluating the agro-biological effectiveness of Azospirillum sp. on tomato

  4. Novas bactérias diazotróficas endofíticas na cultura do trigo em interação com a adubação nitrogenada, no campo Interaction of new diazotrophic endophytic bacteria and nitrogen fertilization on wheat crop under field conditions

    Directory of Open Access Journals (Sweden)

    Valeria Marino Rodrigues Sala

    2008-06-01

    Full Text Available Bactérias diazotróficas pertencentes a diferentes espécies podem estar associadas a gramíneas, como o trigo, promovendo incrementos no crescimento e na produtividade de grãos. Foi realizado um experimento, em condições de campo, com o objetivo de avaliar os benefícios e a viabilidade econômica da inoculação de novos isolados homólogos de bactérias diazotróficas endofíticas em genótipos de trigo sob diferentes doses de N. Foram empregados três isolados de bactérias diazotróficas endofíticas (IAC-AT-8-Azospirillum brasiliense, IAC-HT-11-Achromobacter insolitus e IAC-HT-12-Zoogloea ramigera, dois genótipos de trigo (ITD- 19-Triticum durum L. e IAC-370-Triticum aestivum hard L. e três doses de N (0, 60 e 120 kg ha-1. Foram avaliados, no estádio de perfilhamento e de maturidade fisiológica, a matéria seca, o N acumulado e o índice de eficiência de utilização do N na parte aérea e na colheita; a produtividade de grãos, os componentes de rendimento e os índices de colheita para biomassa e N. No estádio de perfilhamento, somente houve aumento na produção de biomassa com a inoculação de Azospirillum brasiliense e Achromobacter insolitus no genótipo IAC-370, com a adição de N. Entretanto, não houve especificidade dos genótipos de trigo empregados e essas novas bactérias diazotróficas endofíticas para as demais caracaterísticas avaliadas. Houve aumento no acumulado de N na espiga com a inoculação de Azospirillum brasiliense. A inoculação de Achromobacter insolitus propiciou aumento da produtividade de grãos, na maior dose de N utilizada (120 kg ha-1. A inoculação, embora não tenha substituído a adubação nitrogenada, reverteu-se em lucro para o agricultor.Diazotrophic bacteria belonging to different species may be associated with grasses, such as wheat, promoting increases in plant growth and grain yield. A field experiment was carried out to evaluate the benefits and economic viability of inoculation

  5. Effect of Plant Growth Promoting Rhizobacteria (PGPR on Yield and Yield Components of Sesame (Sesamum indicum l. with Emphasize on Environmental Friendly Operations

    Directory of Open Access Journals (Sweden)

    P Rezvani Moghaddam

    2015-07-01

    Full Text Available In order to evaluate the effects of different plant growth promoting rhizobacteria (PGPR on yield and yield components of sesame, an experiment was conducted in the form of Randomized Complete Block Design with three replications at Research Station, Faculty of Agriculture, Ferdowsi University of Mashhad in year 2009. Treatments were: 1 Nitragin (containing of Azotobacter sp., Azospirillum sp. and Pseudomonas sp., 2 Nitroxin (containing of Azotobacter sp. and Azospirillum sp., 3 Super nitro plus (containing of Azospirillum sp., Bacillus sp. and Pseudomonas sp., 4 Phosphate suloblizing bacteria (containing of Bacillus sp. and Pseudomonas sp., 5 Bio Phosphate (containing of Bacillus sp. and Pseudomonas sp., 6 Nitroxin + Phosphate suloblizing bacteria, 7 Nitroxin + Bio Phosphate and control. The results showed that seed yield affected by PGPR and Nitroxin + Phosphate suloblizing bacteria treatment had superior effect on seed yield compared to other treatments. Superior effect of Nitroxin + Phosphate suloblizing bacteria treatment also was shown on plant seed weight and harvest index. Nitragin, Nitroxin + Bio Phosphate, Nitroxin + Phosphate suloblizing bacteria, Bio Phosphate, Phosphate suloblizing bacteria, Nitroxin treatments increased dry weight of capsules per plant of 62, 53, 51, 36 and 30 percent compared to control, respectively. Although, the effect of PGPR was not significant on sesame seed oil content but Bio Phosphate and Nitragin treatments increased seed oil content by 1 and 1.5 percent, respectively. In general, results showed utilization of PGPR can improve seed yield and seed oil content, which can decrease dependence of sesame seed production to chemical fertilizer, decrease negative environmental impacts and as an ecofriendly inputs can help to produce crops and sustainable agriculture guidlines.

  6. Effect of arbuscular mycorrhizal fungi and multi-combination of bioinoculants on regenerated seedlings of cotton

    International Nuclear Information System (INIS)

    Pindi, P.K.; Sultana, T.

    2014-01-01

    Effect of arbuscular mycorrhizal fungi and multi-combination of bioinoculants on regenerated seedlings of cotton Cotton, referred as 'The white gold' is an important commercial crop in India and stands third in the world by means of area of cultivation. Cotton plant regeneration from callus by somatic embryogenesis and its efficiency has been improved significantly in recent times. Our primary investigation was on regenerative studies and multiple shoot induction system focusing mainly on meristematic tissues like seedling cotyledonary nodal explants in RAH-9750 cotton cultivar. An attempt has been made to improve the rate of surveillance and growth of regenerated cotton seedlings by bio-inoculant (mainly AMF) treatment under greenhouse conditions. Out of a total seven pure cultures of AMF fungi, R1-R2 have shown maximum mycorrhizal colonization with RAH-9750 (R) and was identified as Glomus mosseae. This variety was also tested with three different bioinoculants i.e., Rhizobium sp. RHPU-7, Azospirillum sp. PPK-27, Bacillus sp. PU-1, apart from AMF R1-R2 in different combinations. The cotton seedlings have shown the best results in single, dual, triple and multiple combinations i.e R+R1-R2, R+R1-R2+Rhizobium, R+R1-R2+Rhizobium+Azospirillum and R+R1-R2+Rhizobium+Azospirillum+Bacillus respectively. The growth of cotton plants (RAH-9750) generated from meristematic tissue culture was found to be increasing significantly when compared with the normal seeds. Similar results were noticed when the same experiment was subjected to the different soil types of Mahabubnagar district. The investigation clearly infers that better yield of cotton RAH-9750 (R) could be achieved by treating the regenerated cotton seedlings with bioinoculants in different combination in various soil types of Mahabubnagar district. (author)

  7. Composted Cattle Manure Increases Microbial Activity and Soil Fertility More Than Composted Swine Manure in a Submerged Rice Paddy

    Directory of Open Access Journals (Sweden)

    Suvendu Das

    2017-09-01

    Full Text Available Livestock waste composts with minimum inorganic fertilizer as a soil amendment in low-input intensive farming are a feasible agricultural practice to improve soil fertility and productivity and to mitigate soil degradation. The key benefits of the practice rely on the activities of soil microorganisms. However, the role of different livestock composts [composted cattle manure (CCM vs. composted swine manure (CSM] on soil microbes, their activities and the overall impact on soil fertility and productivity in a flooded paddy remains elusive. This study compares the effectiveness of CCM and CSM amendment on bacterial communities, activities, nutrient availability, and crop yield in a flooded rice cropping system. We used deep 16S amplicon sequencing and soil enzyme activities to decipher bacterial communities and activities, respectively. Both CCM and CSM amendment significantly increased soil pH, nutrient availability (C, N, and P, microbial biomass, soil enzyme activities indicative for C and N cycles, aboveground plant biomass and grain yield. And the increase in above-mentioned parameters was more prominent in the CCM treatment compared to the CSM treatment. The CCM amendment increased species richness and stimulated copiotrophic microbial groups (Alphaproteobacteria, Betaproteobacteria, and Firmicutes which are often involved in degradation of complex organic compounds. Moreover, some dominant species (e.g., Azospirillum zeae, Azospirillum halopraeferens, Azospirillum rugosum, Clostridium alkalicellulosi, Clostridium caenicola, Clostridium termitidis, Clostridium cellulolyticum, Magnetospirillum magnetotacticum, Pleomorphomonas oryzae, Variovorax boronicumulans, Pseudomonas xanthomarina, Pseudomonas stutzeri, and Bacillus niacini which have key roles in plant growth promotion and/or lignocellulose degradation were enhanced under CCM treatment compared to CSM treatment. Multivariate analysis revealed that soil pH and available carbon (C and

  8. Selección y caracterización de rizobacterias promotoras de crecimiento vegetal (RPCV asociadas al cultivo de algodón (Gossypium hirsutum

    Directory of Open Access Journals (Sweden)

    Andrés Guzmán

    2012-01-01

    Full Text Available Título en ingles: Selection and characterization of plant growth promoting rhizobacteria (PGPR’s associated with cotton crop (Gossypium hirsutum Resumen: Como parte de las estrategias de una agricultura sostenible, se hace necesario disminuir el uso de fertilizantes nitrogenados de síntesis, mediante la utilización de los biofertilizantes. En particular, los géneros Azotobacter y Azospirillum son utilizados como agentes promotores de crecimiento vegetal debido a su capacidad para fijar nitrógeno atmosférico y producir hormonas de tipo indólico. Por tal razón, en este estudio se aislaron bacterias diazotróficas de los géneros Azotobacter y Azospirillum a partir de la rizósfera de cultivos de algodón en el Espinal (Tolima. Las poblaciones microbianas se caracterizaron fenotípicamente en los medios de cultivo semiespecíficos: Ashby y LG (Azotobacter sp. y NFb, LGI y Batata (Azospirillum sp.. La promoción de crecimiento vegetal se determinó mediante la actividad de la enzima nitrogenasa por medio de la técnica de reducción de acetileno y producción de índoles por el método colorimétrico de Salkowsky. Se obtuvieron 9 aislamientos tentativos de Azotobacter sp. y 4 de Azospirillum sp. Se presentaron diferencias significativas en la prueba de reducción de acetileno con las cepas presuntivas de Azotobacter sp.: NAT 9 (206.43 nmol C2H2 mL-1.h-1, NAT 4, (292.77 nmol C2H2 mL-1.h-1, y NAT 6 (460.60 nmol C2H2 mL-1.h-1 y en la producción de índoles de las cepas NAT 19 (19.87 μg.mL-1 y NAT 13 (20.08 μg.mL-1. Por su eficiencia in vitro en la promoción de crecimiento vegetal se seleccionaron las cepas NAT9, NAT4, NAT6, NAT19 y NAT13 para ser evaluadas como principio activo en futuros inoculantes para el algodón en esta zona del departamento del Tolima. Palabras clave: fijación biológica de nitrógeno; producción de índoles; promoción del crecimiento vegetal;  biofertilizantes. Abstract: As part of strategies for sustainable

  9. Fertilizer nitrogen prescription for cotton by 15N recovery method under integrated nutrient management using soil test crop response function

    International Nuclear Information System (INIS)

    Arulmozhiselvan, K.; Govindaswamy, M.; Chellamuthu, S.

    2007-01-01

    Fertilizer efficiency is a vital parameter in prescription functions to compute fertilizer requirements of crops for achieving a specific yield target. In Soil Test Crop Response (STCR) function, nitrogen fertilizer efficiency is calculated by Apparent N Recovery (ANR) method, which includes the effect of added N interaction (ANI) on soil N reserves. In order to exclude soil effect and refine STCR function, the real efficiency of fertilizer N was estimated by 15 N recovery method. By fitting 15 N recovery in the function, the fertilizer N required for a specific yield target of cotton was estimated. The estimated N requirement by 15 N recovery method was lesser than ANR method when available soil N relatively increased. The approach also fine-tuned the N contributing efficiency of soil, farmyard manure and Azospirillum under Integrated Nutrient Management (INM). For achieving 25 q of seed cotton yield in a soil having 220 kg of available N ha -1 , the predicted N requirement was 159 kg ha -1 under ANR method, whereas in 15 N recovery method fertilizer N to be applied was 138 kg ha -1 with urea alone and 79 kg ha -1 with urea + FYM + Azospirillum. (author)

  10. Effect of pesticides on soil microbial community.

    Science.gov (United States)

    Lo, Chi-Chu

    2010-07-01

    According to guidelines for the approval of pesticides, information about effects of pesticides on soil microorganisms and soil fertility are required, but the relationships of different structures of pesticides on the growth of various groups of soil microorganisms are not easily predicted. Some pesticides stimulate the growth of microorganisms, but other pesticides have depressive effects or no effects on microorganisms. For examples, carbofuran stimulated the population of Azospirillum and other anaerobic nitrogen fixers in flooded and non-flooded soil, but butachlor reduced the population of Azospirillum and aerobic nitrogen fixers in non-flooded soil. Diuron and chlorotoluron showed no difference between treated and nontreated soil, and linuron showed a strong difference. Phosphorus(P)-contains herbicides glyphosate and insecticide methamidophos stimulated soil microbial growth, but other P-containing insecticide fenamiphos was detrimental to nitrification bacteria. Therefore, the following review presents some data of research carried out during the last 20 years. The effects of twenty-one pesticides on the soil microorganisms associated with nutrient and cycling processes are presented in section 1, and the applications of denaturing gradient gel electrophoresis (DGGE) for studying microbial diversity are discussed in section 2.

  11. Phytoremediation of Polycyclic Aromatic Hydrocarbons in Soils Artificially Polluted Using Plant-Associated-Endophytic Bacteria and Dactylis glomerata as the Bioremediation Plant.

    Science.gov (United States)

    Gałązka, Ann; Gałązka, Rafał

    2015-01-01

    The reaction of soil microorganisms to the contamination of soil artificially polluted with polycyclic aromatic hydrocarbons (PAHs) was evaluated in pot experiments. The plant used in the tests was cock's foot (Dactylis glomerata). Three different soils artificially contaminated with PAHs were applied in the studies. Three selected PAHs (anthracene, phenanthrene, and pyrene) were used at the doses of 100, 500, and 1000 mg/kg d.m. of soil and diesel fuel at the doses of 100, 500, and 1000 mg/kg d.m. of soil. For evaluation of the synergistic effect of nitrogen fixing bacteria, the following strains were selected: associative Azospirillum spp. and Pseudomonas stutzerii. Additionally, in the bioremediation process, the inoculation of plants with a mixture of the bacterial strains in the amount of 1 ml suspension per 500 g of soil was used. Chamber pot-tests were carried out in controlled conditions during four weeks of plant growth period. The basic physical, microbiological and biochemical properties in contaminated soils were determined. The obtained results showed a statistically important increase in the physical properties of soils polluted with PAHs and diesel fuel compared with the control and also an important decrease in the content of PAHs and heavy metals in soils inoculated with Azospirillum spp. and P. stutzeri after cock's foot grass growth. The bioremediation processes were especially intensive in calcareous rendzina soil artificially polluted with PAHs.

  12. Salinity tolerance of Dodonaea viscosa L. inoculated with plant growth-promoting rhizobacteria: assessed based on seed germination and seedling growth characteristics

    Directory of Open Access Journals (Sweden)

    Yousefi Sonia

    2017-06-01

    Full Text Available The study was conducted to evaluate the potential of different strains of plant growth-promoting rhizobacteria (PGPR to reduce the effects of salinity stress on the medicinal hopbush plant. The bacterium factor was applied at five levels (non-inoculated, inoculated by Pseudomonas putida, Azospirillum lipoferum + Pseudomonas putida, Azotobacter chroococcum + Pseudomonas putida, and Azospirillum lipoferum + Azotobacter chroococcum + Pseudomonas putida, and the salinity stress at six levels: 0, 5, 10, 15, 20, and 50 dS m-1. The results revealed that Pseudomonas putida showed maximal germination percentage and rate at 20 dS m-1 (18.33% and 0.35 seed per day, respectively. The strongest effect among the treatments was obtained with the treatment combining the given 3 bacteria at 15 dS m-1 salinity stress. This treatment increased the root fresh and dry weights by 31% and 87.5%, respectively (compared to the control. Our results indicate that these bacteria applied on hopbush affected positively both its germination and root growth. The plant compatibility with the three bacteria was found good, and the treatments combining Pseudomonas putida with the other one or two bacteria discussed in this study can be applied in nurseries in order to restore and extend the area of hopbush forests and akin dry stands.

  13. Associative diazotrophic bacteria in grass roots and soils from heavy metal contaminated sites.

    Science.gov (United States)

    Moreira, Fátima M S; Lange, Anderson; Klauberg-Filho, Osmar; Siqueira, José O; Nóbrega, Rafaela S A; Lima, Adriana S

    2008-12-01

    This work aimed to evaluate density of associative diazotrophic bacteria populations in soil and grass root samples from heavy metal contaminated sites, and to characterize isolates from these populations, both, phenotypically (Zinc, Cadmium and NaCl tolerance in vitro, and protein profiles) and genotypically (16S rDNA sequencing), as compared to type strains of known diazotrophic species. Densities were evaluated by using NFb, Fam and JNFb media, commonly used for enrichment cultures of diazotrophic bacteria. Bacterial densities found in soil and grass root samples from contaminated sites were similar to those reported for agricultural soils. Azospirillum spp. isolates from contaminated sites and type strains from non-contaminated sites varied substantially in their in vitro tolerance to Zn+2 and Cd+2, being Cd+2 more toxic than Zn+2. Among the most tolerant isolates (UFLA 1S, 1R, S181, S34 and S22), some (1R, S34 and S22) were more tolerant to heavy metals than rhizobia from tropical and temperate soils. The majority of the isolates tolerant to heavy metals were also tolerant to salt stress as indicated by their ability to grow in solid medium supplemented with 30 g L(-1) NaCl. Five isolates exhibited high dissimilarity in protein profiles, and the 16S rDNA sequence analysis of two of them revealed new sequences for Azospirillum.

  14. Sensitivity of some nitrogen fixers and the target pest Fusarium oxysporum to fungicide thiram.

    Science.gov (United States)

    Osman, Awad G; Sherif, Ashraf M; Elhussein, Adil A; Mohamed, Afrah T

    2012-03-01

    This study was carried out to investigate the toxic effects of the fungicide thiram (TMTD) against five nitrogen fixers and the thiram target pest Fusarium oxysporum under laboratory conditions. Nitrogen fixing bacteria Falvobacterium showed the highest values of LD(50) and proved to be the most resistant to the fungicide followed by Fusarium oxysporum, while Pseudomonas aurentiaca was the most affected microorganism. LD(50) values for these microorganisms were in 2-5 orders of magnitude lower in comparison with LD(50) value for Fusarium oxysporum. Thiram was most toxic to Pseudomonas aurentiaca followed by Azospirillum. The lowest toxicity index was recorded for Fusarium oxysporum and Flavobacterium. The slope of the curve for Azomonas, Fusarium oxysporum and Flavobacterium is more steep than that of the other curves, suggesting that even a slight increase of the dose of the fungicide can cause a very strong negative effect. Thiram was more selective to Pseudomonas aurentiaca followed by Azospirillum, Rhizobium meliloti and Azomonas. The lowest selectivity index of the fungicide was recorded for Falvobacterium followed by Fusarium oxysporum. The highest safety coefficient of the fungicide was assigned for Flavobacterium, while Pseudomonas aurentiaca showed the lowest value.

  15. Cultivation-Based and Molecular Assessment of Bacterial Diversity in the Rhizosheath of Wheat under Different Crop Rotations.

    Directory of Open Access Journals (Sweden)

    Muhammad Tahir

    Full Text Available A field study was conducted to compare the formationand bacterial communities of rhizosheaths of wheat grown under wheat-cotton and wheat-rice rotation and to study the effects of bacterial inoculation on plant growth. Inoculation of Azospirillum sp. WS-1 and Bacillus sp. T-34 to wheat plants increased root length, root and shoot dry weight and dry weight of rhizosheathsoil when compared to non-inoculated control plants, and under both crop rotations. Comparing both crop rotations, root length, root and shoot dry weight and dry weight of soil attached with roots were higher under wheat-cotton rotation. Organic acids (citric acid, malic acid, acetic acid and oxalic acid were detected in rhizosheaths from both rotations, with malic acid being most abundant with 24.8±2 and 21.3±1.5 μg g(-1 dry soil in wheat-cotton and wheat-rice rotation, respectively. Two sugars (sucrose, glucose were detected in wheat rhizosheath under both rotations, with highest concentrations of sucrose (4.08±0.5 μg g(-1 and 7.36±1.0 μg g(-1 and glucose (3.12±0.5 μg g(-1 and 3.01± μg g(-1 being detected in rhizosheaths of non-inoculated control plants under both rotations. Diversity of rhizosheath-associated bacteria was evaluated by cultivation, as well as by 454-pyrosequencing of PCR-tagged 16S rRNA gene amplicons. A total of 14 and 12 bacterial isolates predominantly belonging to the genera Arthrobacter, Azospirillum, Bacillus, Enterobacter and Pseudomonaswere obtained from the rhizosheath of wheat grown under wheat-cotton and wheat-rice rotation, respectively. Analysis of pyrosequencing data revealed Proteobacteria, Bacteriodetes and Verrucomicrobia as the most abundant phyla in wheat-rice rotation, whereas Actinobacteria, Firmicutes, Chloroflexi, Acidobacteria, Planctomycetes and Cyanobacteria were predominant in wheat-cotton rotation. From a total of 46,971 sequences, 10.9% showed ≥97% similarity with 16S rRNA genes of 32 genera previously shown to include

  16. Isolation and Identification of Phosphate Solubilizing and Nitrogen Fixing Bacteria from Soil in Wamena Biological Garden, Jayawijaya, Papua

    Directory of Open Access Journals (Sweden)

    SRI WIDAWATI

    2005-07-01

    Full Text Available A study was undertaken to investigate the occurrence of phosphate solubilizing bacteria (PSB and nitrogen-fixing bacteria (NFB from soil samples of Wamena Biological Garden (WbiG. Eleven soil samples were collected randomly to estimate microbial population which used plate count method. The result showed that the microbial population ranged from 5.0x103-7.5x106 cells of bacteria/gram of soil and 5.0x103-1.5x107 cells of bacteria/gram of soil for PSB and NFB respectively. There were 17 isolates which have been identified till genus and species. The isolated microorganism were identified as PSB i.e. Bacillus sp., B. pantothenticus, B. megatherium, Flavobacterium sp., F. breve, Klebsiella sp., K. aerogenes, Chromobacterium lividum, Enterobacter alvei, E. agglomerans, Pseudomonas sp., Proteus sp. and as NFB i.e. Azotobacter sp., A. chroococcum, A. paspalii, Rhizobium sp., and Azospirillum sp.

  17. Associative diazotrophic bacteria in grass roots and soils from heavy metal contaminated sites

    Directory of Open Access Journals (Sweden)

    Fátima M.S. Moreira

    2008-12-01

    Full Text Available This work aimed to evaluate density of associative diazotrophic bacteria populations in soil and grass root samples from heavy metal contaminated sites, and to characterize isolates from these populations, both, phenotypically (Zinc, Cadmium and NaCl tolerance in vitro, and protein profiles and genotypically (16S rDNA sequencing, as compared to type strains of known diazotrophic species. Densities were evaluated by using NFb, Fam and JNFb media, commonly used for enrichment cultures of diazotrophic bacteria. Bacterial densities found in soil and grass root samples from contaminated sites were similar to those reported for agricultural soils. Azospirillum spp. isolates from contaminated sites and type strains from non-contaminated sites varied substantially in their in vitro tolerance to Zn+2 and Cd+2, being Cd+2 more toxic than Zn+2. Among the most tolerant isolates (UFLA 1S, 1R, S181, S34 and S22, some (1R, S34 and S22 were more tolerant to heavy metals than rhizobia from tropical and temperate soils. The majority of the isolates tolerant to heavy metals were also tolerant to salt stress as indicated by their ability to grow in solid medium supplemented with 30 g L-1 NaCl. Five isolates exhibited high dissimilarity in protein profiles, and the 16S rDNA sequence analysis of two of them revealed new sequences for Azospirillum.Objetivou-se avaliar a densidade de populações de bactérias diazotróficas associativas em amostras de solos e de raízes de gramíneas oriundas de sítios contaminados com metais pesados, e caracterizar isolados destas populações através da análise fenotípica (tolerância aos metais pesados zinco e cádmio e à NaCl in vitro, perfis protéicos, e genotípica (seqüenciamento de 16S rDNA, comparados às estirpes tipo das mesmas espécies. As densidades foram avaliadas nos meios NFb, Fam e LGI, comumente utilizados para culturas de enriquecimento de populações de bactérias diazotróficas associativas. As densidades

  18. The influence of agro-industrial effluents on River Nile pollution

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    Sayeda M. Ali

    2011-01-01

    Full Text Available The major agro-industrial effluents of sugarcane and starch industries pose a serious threat to surface waters. Their disposal in the River Nile around Cairo city transitionally affected the microbial load. In situ bacterial enrichment (50–180% was reported and gradually diminished downstream; the lateral not vertical effect of the effluent disposal was evident. Disposed effluents increased BOD and COD, and then progressively decreased downstream. Ammoniacal N was elevated, indicating active biological ammonification and in situ biodegradability of the effluents. In vitro, the nitrogen-fixing rhizobacteria Crysomonas luteola, Azospirillum spp., Azomonas spp. and K. pneumoniae successfully grew in batch cultures prepared from the crude effluents. This was supported by adequate growth parameters and organic matter decomposition. Therefore, such biodegradability of the tested agro-industrial effluents strongly recommends their use for microbial biomass necessary for the production of bio-preparates.

  19. Biofilm comprising phototrophic, diazotrophic, and hydrocarbon-utilizing bacteria: a promising consortium in the bioremediation of aquatic hydrocarbon pollutants.

    Science.gov (United States)

    Al-Bader, Dhia; Kansour, Mayada K; Rayan, Rehab; Radwan, Samir S

    2013-05-01

    Biofilms harboring simultaneously anoxygenic and oxygenic phototrophic bacteria, diazotrophic bacteria, and hydrocarbon-utilizing bacteria were established on glass slides suspended in pristine and oily seawater. Via denaturing gradient gel electrophoresis analysis on PCR-amplified rRNA gene sequence fragments from the extracted DNA from biofilms, followed by band amplification, biofilm composition was determined. The biofilms contained anoxygenic phototrophs belonging to alphaproteobacteria; pico- and filamentous cyanobacteria (oxygenic phototrophs); two species of the diazotroph Azospirillum; and two hydrocarbon-utilizing gammaproteobacterial genera, Cycloclasticus and Oleibacter. The coexistence of all these microbial taxa with different physiologies in the biofilm makes the whole community nutritionally self-sufficient and adequately aerated, a condition quite suitable for the microbial biodegradation of aquatic pollutant hydrocarbons.

  20. Evaluation of Four Bio fertilizers for Bioremediation of Pesticide contaminated Soil

    International Nuclear Information System (INIS)

    El- Kabbany, S.

    1999-01-01

    Experiments were conducted to asses the ability of mixed populations of microorganisms which produced as a bio fertilizers by the General Organization of Agriculture Fund, Ministry of Agriculture, Egypt (phosphoren, microbien, cerealin and azospirillum) to degrade five selected pesticides representing different classes including organophosphate, carbamate and chlorinated organic compounds. There were differences in rates of biotransformation, suggesting the selective induction of certain metabolic enzymes. Inoculation of soil incorporated with malathion, fenamiphos, carbaryl, aldicarb and dieldrin, resulted in ca. 80-90% removal of malathion and fenamiphos within 8 days, carbaryl and aldicarb within 11-15 days respectively. Dieldrin removal occurred slowly within 2 months. These data suggest that bioremediate may act as potential candidates for soil inoculation to bioremediate pesticide contaminated soil. The production of Co2 (soil respiration ) was stimulated by some pesticides. In samples with microbien, an about 2 times higher Co2 production was measured

  1. Inoculant production in developing countries - Problems, potentials and success

    International Nuclear Information System (INIS)

    Kannaiyan, S.

    2001-01-01

    Sustainable agriculture is a long-term goal that seeks to overcome some of problems and constraints that confront the economic viability, environmental soundness and social acceptance of agricultural production systems. In this context, bio-fertilizers assume special significance particularly because they are 'eco-friendly', but also since their alternative, chemical fertilizers are expensive. Undoubtedly, the most commonly used bio-fertilizers are soil bacteria of the genus Rhizobium, but others like Azolla, Azospirillum, various cyanobacteria also contribute significant amounts of N to e.g. rice. Other bacteria like Frankia and Acetobacter contribute N to trees of the genus Casuarina and sugarcane, respectively. Furthermore, although they are rarely used as inoculants, vesicular arbuscular mycorrhizae (VAM) and phosphobacteria help countless plants solubilise and assimilate soil phosphorus. Despite these advantages, bio-fertilizers could be more widely used in developing countries. Contingent upon greater use is improved quality of the inoculants, and all aspects of their production are discussed here. (author)

  2. Studies on utilization of nitrogen-fixing bacteria for saving energy; Chisso koteikin no katsuyo ni yoru sho energy no kenkyu

    Energy Technology Data Exchange (ETDEWEB)

    Uozumi, T; Koyama, R; Horiuchi, M; Hidaka, M; Masaki, H [The University of Tokyo, Tokyo (Japan); Shigematsu, T; Inoue, A [New Energy and Industrial Technology Development Organization, Tokyo, (Japan)

    1997-02-01

    This paper describes analysis and enhancement of nitrogen-fixing gene of rice root bacteria, such as Klebsiella oxytoca, Azospirillum lipoferumn and Sphingomonas paucimobilis, for realizing energy saving through conservation of nitrogenous fertilizers. For K. oxytoca, modified strain R-16 was developed, which can fix nitrogen effectively even in the presence of NH4{sup +}. Nitrogen-fixing ability of A. lipoferumn depends on the activity control by the modification of nitrogen-fixing enzyme as well as on the adjustment of transcription level by the transcription activating gene, nifA. The control gene relating to the above was analyzed by making clones. As a result, a modified strain TAl without the control by NH4{sup +} was developed. The R-16 and TAl strains were inoculated into rice sterile-cultured without nitrogen. Consequently, inoculated strains were settled in the root, which resulted in the increased vegetation weight of plant to two times heavier than that without inoculation. 9 refs.

  3. Antisera production to detect indoleacetic acid in cultures of plant-growth promoting bacteria

    International Nuclear Information System (INIS)

    Rojas, Marcia M; Hernandez, Annia; Rives, Narovis; Tejera, Berto; Acebo, Yanelis; Heydrich, Mayra

    2012-01-01

    Rabbit polyclonal antisera against indoleacetic acid (IAA) bound to nitrocellulose membrane were obtained, which exhibited a high titer and specificity. The dot immunobinding technique with colloidal gold was used to detect auxin production by several strains belonging to Gluconacetobacter, Herbaspirillum, Azospirillum, Pseudomonas, Burkholderia and Bacillus genera, using culture supernatants as antigens. Moreover, auxin production was quantified by the Salkowski's method to corroborate the previous results. It was found that that all the studied microorganisms produce IAA and the feasibility of using these antisera to detect the metabolite was confirmed. Taking into account the potentialities of plant growth promoting bacteria as biofertilizers, the use of these antisera for a rapid and easy detection of IAA in bacteria associated with important crops is thus recommended.

  4. Effect of some plant growth promoting rhizobacteria and nitrogen fertilizer on morphological characteristics of german chamomile (Matricaria chamomilla L.

    Directory of Open Access Journals (Sweden)

    S. Dastborhan

    2016-04-01

    Full Text Available .In order to investigate the effects of plant growth promoting rhizobacteria and nitrogen fertilizer on morphological traits of german chamomile (Matricaria chamomilla L., a field experiment was carried out as factorial based on randomized complete block design with three replications in Research Farm of the Faculty of Agriculture, University of Tabriz, Iran, during 2007-2008. Factors were inoculation with plant growth promoting rhizobacteria (B0: no-inoculation, B1: inoculation with Azotobacter chroocuccum, B2: inoculation with Azospirillum lipoferum and B3: inoculation with a mixture of two bacteria and nitrogen fertilizer (N0:0, N1:50, N2:100 and N3:150 kgN.ha-1. Results showed that inoculation with bacteria significantly improved plant height, stem diameter, number of lateral branches, number of flowers per plant, dry weight of flowers, stems, leaves and total dry weight per plant. These traits were significantly similar for inoculation with Azotobacter, inoculation with Azospirillum and inoculation with a mixture of two bacteria. Effect of nitrogen fertilizer on all traits (except number of lateral branches was positive, but there were no significant differences among 50, 100 and 150 kg.ha-1 nitrogen. The highest and the lowest number and weight of flowers per plant were recorded for inoculation + 50 kg.ha-1 nitrogen application and no-inoculation + no-fertilizer, respectively. In general, application of biofertilizers had positive and significant effects on morphological traits of german chamomile. In addition, with adding 50 kg N.ha-1 the performance of bacteria increased and the highest flower yield were produced.

  5. Ammonium inhibition of nitrogenase activity in Herbaspirillum seropedicae

    Energy Technology Data Exchange (ETDEWEB)

    Fu, H.; Burris, R.H. (Univ. of Wisconsin, Madison (USA))

    1989-06-01

    The effect of oxygen, ammonium ion, and amino acids on nitrogenase activity in the root-associated N{sub 2}-fixing bacterium Herbaspirillum seropedicae was investigated in comparison with Azospirillum spp. and Rhodospirillum rubrum. H. seropedicae is microaerophilic, and its optimal dissolved oxygen level is from 0.04 to 0.2 kPa for dinitrogen fixation but higher when it is supplied with fixed nitrogen. No nitrogenase activity was detected when the dissolved O{sub 2} level corresponded to 4.0 kPa. Ammonium, a product of the nitrogenase reaction, reversible inhibited nitrogenase activity when added to derepressed cell cultures. However, the inhibition of nitrogenase activity was only partial even with concentrations of ammonium chloride as high as 20 mM. Amides such as glutamine and asparagine partially inhibited nitrogenase activity, but glutamate did not. Nitrogenase in crude extracts prepared from ammonium-inhibited cells showed activity as high as in extracts from N{sub 2}-fixing cells. The pattern of the dinitrogenase and the dinitrogenase reductase revealed by the immunoblotting technique did not change upon ammonium chloride treatment of cells in vivo. No homologous sequences were detected with the draT-draG probe from Azospirillum lipoferum. There is no clear evidence that ADP-ribosylation of the dinitrogenase reductase is involved in the ammonium inhibition of H. seropedicae. The uncoupler carbonyl cyanide m-chlorophenylhydrazone decreased the intracellular ATP concentration and inhibited the nitrogenase activity of whole cells. The ATP pool was significantly disturbed when cultures were treated with ammonium in vivo.

  6. Benefits from Bio and organic fertilization by cucumber (Cucumis Sativus) with application of 15N stable isotope

    International Nuclear Information System (INIS)

    Galal, Y. G. M.; Soliman, S. M.; Ahmed, F. A.; El-Sherbiny, A. E. A.; Dahdouh, S. M.

    2012-12-01

    Benefits from bio and organic fertilizer were evaluated under cucumber (Cucumis Sativus) crop grown on sandy soil at a field scale. The experiment was conducted under drip irrigation system. Fertilization treatment indicated that the combination of 50% mineral fertilizer (MF) + 50% organic compost (OC) was superior over all other fertilization treatment when the fresh weight of cucumber biomass or fruits was considered. It means that half of the recommended dose of of mineral fertilizer is enough to meet the requirement of cucumber crop when supplemented with organic compost. Nitrogen derived from mineral fertilizer (Ndff) by cucumber at different plant growth stages was significantly affected by the rate of addition and enhanced with microbial inoculation. Arbuscular mycorrhizea (AMF) was superior over Azospirillum and Rhizobium inoculations. The enhancement of Ndff uptake by plants was more pronounced at the fruit stage than at vegetative, flowering and hay growth stages. The highest values of Ndfa were induced by Rhizobium at hay stage followed by fruit. Similar trend, but to different extents was noticed with AMF and Azospirillum inoculum s. Most of nitrogen derived from compost (Ndfc) was occurred by addition of 50% MF + 50% Oc. Rhizobium and AMF were more effective than Azospirilum. High quantities of Ndfc were recognized at hay stage compared to other growth stages.The efficient use of mineral fertilizer-N (%NUE) was increased by addition of half:half mineral and organic fertilizer. Similarly, it seems that microbial inoculation in general has a synergistic effect on enhancement of %NUE. Higher NUE occurred at hay growth stage than others. (Author)

  7. OCORRÊNCIA E ATIVIDADE DE BACTÉRIAS DIAZOTRÓFICAS EM FORRAGEIRAS CULTIVADAS NA REGIÃO SEMIÁRIDA NO BRASIL

    Directory of Open Access Journals (Sweden)

    MÁRCIA CARNEIRO MONTEIRO DOS SANTOS

    2013-01-01

    Full Text Available Diazotrophic bacteria play important role on economy nitrogen fertilizer in forage glasses and environmental sustainability. With the objective of evaluate the occurrence of diazotrophic bacteria associated associated with native forage at two different times and identify isolates with potential for fixing N2 in the semiarid region. Was conducted in the Soil Laboratory of the Centro de Saúde e Tecnologia Rural in Federal University of Campina Grande, Campus de Patos, Paraíba. A study was carried out at the Soil Laboratory of the Centro de Saúde e Tecnologia Rural of the Federal University of Campina Grande, in Patos, Paraíba. The objective this study was to verify in the native diazotrophic endophytic bacteria associated with forage glasses and to identify isolates in NBF hability, during the rainy and dry seasons in semiarid region. Root samples of three forage grasses [Andropogon gayanus Kunth (Andropogon, Panicum maximum Jacq. cv. Tanzania (Tanzânia and Cenchrus ciliaris L. (Buffel] cultivated in the field experiment was utilized. The bacteria were isolated in NFb culture media free-N specific for Azospirillum spp., the isolates was quantified, phenotypically characterized, purified. From caracterized after, was evaluated for their nitrogenase activity in vitro. The resultas show diazotrophics bacteria growth in the three forage grasses tested. The ocorrency diazotrophics bacteria be influencied by genotipic plant and seasonal variation. A more density of NSDB of the genus Azospirillum associated in the root grasses were obtained in dry season. The NSDB isolates, show a high potencial for new studies on the genetic caracteristcs and avaliation the inoculo potential to (BNF associated on grasses in semiarid region.

  8. bio fertilization of soybean in sandy soils of egypt using N-15 tracer technique

    International Nuclear Information System (INIS)

    Soliman, S.; Galal, Y.G.M.; Elghandour, I.

    1995-01-01

    The effect of inoculation of soybeans with B. Japonicum and A. brasilense either solely or in mixture, and N fertilizer levels had been studied in pot experiment Nodulation of soybean grown in sandy soil was enhanced by inoculation. The highest values of nodules number and fresh weight were recorded at rate of 20 Kg N ha-1, and decreased with increasing N rate up to 40 kg N ha-1. In contrast, the dry weight of the above ground parts, as well as the N uptake was increased with increasing N fertilizer level. Similar effect was observed for inoculation as compared with the un inoculated treatment. Despite the nodulating and nonnodulating soybeans has almost the same dry weight, the nodulating isoline accumulated more N than the non-nodulating. Percentages of nitrogen derived from air (%Ndfa) was depressed with increasing N rates from 10 to 40 kg N ha-1 either estimated by isotope dilution (I D) or N difference method (D M). Dual inoculation resulted in high percent of N 2-fixed (42.5%) at rate of 10 kg N ha-1. Correlation between I D and D M methods was found to be dependent on inoculation treatments. However, nitrogen utilized by nodulating soybean (FUE%) was enhanced as a function of inoculation with B. Japonicum. 2 figs., 3 tabs

  9. Bio fertilization of soybean in sandy soils of egypt using N-15 tracer technique

    Energy Technology Data Exchange (ETDEWEB)

    Soliman, S; Galal, Y G.M.; Elghandour, I [Soil and Water Dept, Atomic Energy Authority, P.O.Box 13756 (Egypt)

    1995-10-01

    The effect of inoculation of soybeans with B. Japonicum and A. brasilense either solely or in mixture, and N fertilizer levels had been studied in pot experiment Nodulation of soybean grown in sandy soil was enhanced by inoculation. The highest values of nodules number and fresh weight were recorded at rate of 20 Kg N ha-1, and decreased with increasing N rate up to 40 kg N ha-1. In contrast, the dry weight of the above ground parts, as well as the N uptake was increased with increasing N fertilizer level. Similar effect was observed for inoculation as compared with the un inoculated treatment. Despite the nodulating and nonnodulating soybeans has almost the same dry weight, the nodulating isoline accumulated more N than the non-nodulating. Percentages of nitrogen derived from air (%Ndfa) was depressed with increasing N rates from 10 to 40 kg N ha-1 either estimated by isotope dilution (I D) or N difference method (D M). Dual inoculation resulted in high percent of N 2-fixed (42.5%) at rate of 10 kg N ha-1. Correlation between I D and D M methods was found to be dependent on inoculation treatments. However, nitrogen utilized by nodulating soybean (FUE%) was enhanced as a function of inoculation with B. Japonicum. 2 figs., 3 tabs.

  10. OPCIONES DE MANEJO SOSTENIBLE DEL SUELO EN ZONAS ARIDAS: APROVECHAMIENTO DE LA HALÓFITA Salicornia bigelovii (Torr. Y USO DE BIOFERTILIZANTES EN LA AGRICULTURA MODERNA

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    Edgar Omar Rueda Puente

    2010-12-01

    Full Text Available The study and development of plant resources in arid-saline environments is increasing. Salicornia bigelovii is a halophyte of great interest. However, the productivity of these plants is limited by nitrogen availability. An alternative to chemical fertilizers are the plant growth promoting bacteria and mycorrhizae. In the present study was evaluated the effect of Glomus intraradices, three strains of rhizobacteria (Klebsiella pneumoniae, Bacillus amyloliquefaciens and Azospirillum halopraeferens and two soil types (clayey and sandy on Salicornia under greenhouse conditions. The inoculation of bacteria under conditions of sandy soil significantly stimulated growth and nutritional factor of Salicornia (NPK. Synergism was observed between G. intraradices and rhizobacteria. When inoculated bacteria in individually form, behaved with significant differences. There was synergism between G. intraradices and Klebsiella pneumoniae and A. halopraeferens in the uptake of N, the opposite happened with G. intraradices and Bacillus amyloliquefaciens with high significant values in the absorption of P and K. The soil was a determining factor in behavior and expression of the benefit of the microorganisms. Rhizobacteria and mycorrhiza in the study have potential for use as growth promoters in salicornia.

  11. Effects of water stress and inoculation with plant growth promoting rhizobacteria (PGPR on antioxidant status and photosynthetic pigments in basil (Ocimum basilicum L.

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    Mostafa Heidari

    2012-01-01

    Full Text Available Effects of water stress and inoculation with plant growth promoting rhizobacteria (PGPR on antioxidant activity and photosynthetic pigments were studied in basil plants. A field experiment was conducted at the University of Zabol in Iran during 2010 growing season. The experiment laid out as split plot based on randomized complete block design with three replications. Three levels of water stress W1 = 80 (control, W2 = 60 and W3 = 40% of the field capacity (FC as main plots and four levels of bacterial species consisting of S1 = Pseudomonades sp., S2 = Bacillus lentus, S3 = Azospirillum brasilens, S4 = combination of three bacterial species and S5 = control (without use of bacterial as sub plots. The results revealed that water stress caused a significant change in the antioxidant activity. The highest concentration CAT and GPX activity were in W3 treatments. By increasing water stress from control to W3, chlorophyll content in leaves was increased but Fv/Fm and APX activity decreased. Application of rhizobacteria under water stress improved the antioxidant and photosynthetic pigments in basil plants. S1 = Pseudomonades sp. under water stress, significantly increased the CAT enzyme activity, but the highest GPX and APX activity and chlorophyll content in leaves under water stress were in S4 = combination of three bacterial species.

  12. Differential distribution and abundance of diazotrophic bacterial communities across different soil niches using a gene-targeted clone library approach.

    Science.gov (United States)

    Yousuf, Basit; Kumar, Raghawendra; Mishra, Avinash; Jha, Bhavanath

    2014-11-01

    Diazotrophs are key players of the globally important biogeochemical nitrogen cycle, having a significant role in maintaining ecosystem sustainability. Saline soils are pristine and unexplored habitats representing intriguing ecosystems expected to harbour potential diazotrophs capable of adapting in extreme conditions, and these implicated organisms are largely obscure. Differential occurrence of diazotrophs was studied by the nifH gene-targeted clone library approach. Four nifH gene clone libraries were constructed from different soil niches, that is saline soils (low and high salinity; EC 3.8 and 7.1 ds m(-1) ), and agricultural and rhizosphere soil. Additionally, the abundance of diazotrophic community members was assessed using quantitative PCR. Results showed environment-dependent metabolic versatility and the presence of nitrogen-fixing bacteria affiliated with a range of taxa, encompassing members of the Alphaproteobacteria, Betaproteobacteria, Deltaproteobacteria, Gammaproteobacteria, Cyanobacteria and Firmicutes. The analyses unveiled the dominance of Alphaproteobacteria and Gammaproteobacteria (Pseudomonas, Halorhodospira, Ectothiorhodospira, Bradyrhizobium, Agrobacterium, Amorphomonas) as nitrogen fixers in coastal-saline soil ecosystems, and Alphaproteobacteria and Betaproteobacteria (Bradyrhizobium, Azohydromonas, Azospirillum, Ideonella) in agricultural/rhizosphere ecosystems. The results revealed a repertoire of novel nitrogen-fixing bacterial guilds particularly in saline soil ecosystems. © 2014 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

  13. Aislamiento e identificación de microorganismos con potencial biofertilizante de suelos arroceros del distrito de riego del rio zulia, norte de santander

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    Marilyn Tatiana Santos-Torres

    2006-07-01

    Full Text Available It was evaluated the microbial population of soils cultivated with rice at some zones of the district of irrigation of Zulia River, Norte de Santander state, Colombia, and no cultivated soil with rice. It was found that the seeded soil with rice were significantly low in fungi, bacteria and actinomycete populations compa red with no seeded with rice. This situation was due to possibly excessive use of agricultural machine and excessive application of pesticides and continuous rice monoculture. Therefore, with use the biofertilizer enriched with microorganism isolated from zone with similar agroecological conditions, will improve the microorganism adaptation of the rizosphere and will promote a reestablishment of the biological balance of soils and therefore to increase biotic activity improving the quality and productivity of the cultures. A total of 43 bacteria and 4 fungi were isolated in different soils of the studied zone, and were identified 25 microorganisms. According the isolation methodology, the bacteria were separate in two groups: diazotrophic like the species of the genera Azotobacter sp., Azospirillum sp. and Beijerinckia sp. and the phosphate solubilizate inorganic like Bacillus megaterium, B. cereus, Pseudomonas putida and P. aeruginosa. For the fungi identification were evaluate the micro and macroscopic characteristics in the culture medium Czapeck, following the fungi keys of Samson Hoekstra and Oorsehot (1981, which allowed recognize species like Trichoderma sp., Aspergillus niger, Penicillium purpurogenum, P. pinopilum.

  14. Efecto del uso del suelo sobre rizobacterias fosfatosolubizadoras y diazotroficas en el distrito de riego del río zulia,norte de santander (colombia

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    Ronal Fernando-Cañon

    2009-07-01

    Full Text Available It was quantified the population of diazotrophic and phosphate solubilizer bacteria with the aim of determine the effect of the use of soils during different periods of intervention with culture of rice in three agro-ecological zones of the District of Irrigation of the Zulia river. The results showed that the management of the culture of rice in the different studied zones significantly influenced the population of microorganisms in all the studied culture media, excepting the semi-solid culture media JMV. The populations of the genera Azospirillum spp., Azotobacter spp., Beijerinckia spp., were influenced by the fertility of the soils in the zones of Buena Esperanza and Restauración compared with Limoncito, where the quantities of organic matter and nutritional escential elements were lower. It were obtained 28 isolations of entophytic, associative, free-living diazotrophic and phosphate solubilizer rhizobacteria according with their macroscopic characteristics in the culture media Batata, JMV, Ashby and nutritive, from the analysis of the population in the zones of Buena Esperanza, Restauración and Limoncito. These isolations were purified and preserved in sterilized saline solution (0.85% NaCl at 4°C in the Laboratory of Microbiology of the Colombian Agricultural Institute, ICA, with the purpose to be used in subsequent studies about their potential as biofertilizers in rice cultured soils of the department.

  15. Soil C and N statuses determine the effect of maize inoculation by plant growth-promoting rhizobacteria on nitrifying and denitrifying communities.

    Science.gov (United States)

    Florio, Alessandro; Pommier, Thomas; Gervaix, Jonathan; Bérard, Annette; Le Roux, Xavier

    2017-08-21

    Maize inoculation by Azospirillum stimulates root growth, along with soil nitrogen (N) uptake and root carbon (C) exudation, thus increasing N use efficiency. However, inoculation effects on soil N-cycling microbial communities have been overlooked. We hypothesized that inoculation would (i) increase roots-nitrifiers competition for ammonium, and thus decrease nitrifier abundance; and (ii) increase roots-denitrifiers competition for nitrate and C supply to denitrifiers by root exudation, and thus limit or benefit denitrifiers depending on the resource (N or C) mostly limiting these microorganisms. We quantified (de)nitrifiers abundance and activity in the rhizosphere of inoculated and non-inoculated maize on 4 sites over 2 years, and ancillary soil variables. Inoculation effects on nitrification and nitrifiers (AOA, AOB) were not consistent between the three sampling dates. Inoculation influenced denitrifiers abundance (nirK, nirS) differently among sites. In sites with high C limitation for denitrifiers (i.e. limitation of denitrification by C > 66%), inoculation increased nirS-denitrifier abundance (up to 56%) and gross N 2 O production (up to 84%), likely due to increased root C exudation. Conversely, in sites with low C limitation (<47%), inoculation decreased nirS-denitrifier abundance (down to -23%) and gross N 2 O production (down to -18%) likely due to an increased roots-denitrifiers competition for nitrate.

  16. FY1995 studies on saving energy by use of nitrogen- fixing bacteria; 1995 nendo chisso koteikin no katsuyo ni yoru sho energy no kenkyu

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-03-01

    To save energy by improving the ability of nitrogen-fixing bacteria (Kebsiella oxytoca, Azospirillum lipoferum and Sphingomonas paucimobilis) in the rhizosphere of rice, by means of genetic analysis and engineering of the nif genes. Analysis and improvement of the nif genes were performed in 3 species of nitrogen-fixing bacteria in the rhizoshere of rice. (1) In an facultative anaerobe, K. oxytoca, the repressor gene, nifL was destroyed, and the activator gene, nifA was fortified, to attain a novel mutant strain R16, which fixes nitrogen even in the presence of NH{sub 4}{sup +}. (2) In a microaerophilic nitrogen fixer, A. lipoferum, the regulatory genes draT and draG were cloned and analysed, and an improved strain TA1 was obtained by introduction of K. oxytoca nifA gene. (3) In an aerobic nitrogen-fixer S. paucimobilis, the nifA gene was cloned and sequenced, and the activity was expressed in E. coil to show that the product activates the nif promoters of Azospirillurn and Klebsiella. (4) The improved strains K. oxytoca R16 and A. lipoferun TA1 were inoculated to rice plant cultured in a pot without addition of nitrogen source. The inoculated plant showed twice as much dry weight as the noninoculated plant, showing that the improved strains are effective to stimulate the growth of rice. (NEDO)

  17. Nitrogen fixation by free-living microorganisms in tropical rice soils using labelled fertilizer. Part of a coordinated programme on isotope techniques in studies of biological nitrogen fixation for the dual purpose of increasing crop production and decreasing nitrogen fertilizer use to conserve the environment

    International Nuclear Information System (INIS)

    Rao, V.R.

    1981-11-01

    Both acetylene-reduction and 15 N techniques were used to study heterotrophic N fixation in the rhizosphere of rice plants. Soils subjected to flooding in 4 soil types in both greenhouse and the field were found to stimulate greater heterotrophic nitrogen fixation than moist soils. The addition of organic materials, in particular, cellulose and rice straw, in general, enhanced nitrogen fixed by heterotrophic organisms living in the rhizosphere of rice plants. The highest amount of N fixed was 38 kg N/ha, and was obtained in a flooded lateritic soil to which had been added cellulose. Heterotrophic nitrogen fixation was influenced by soil type. In this study, the lowest value for fixed N was recorded in an acid sulphate soil of low pH. The addition of increasing amounts of inorganic nitrogen fertilizer in the form of ammonium sulphate suppressed rhizospheric nitrogen fixation in all soils, but the extent of suppression differed in the different soils. Benomyl fungicide and methyl carbamate insecticide had a stimulatory effect on heterotrophic nitrogen fixation in soils under rice roots. Different rice cultivars stimulated strains of Azospirillum to varying extent, and thus did not fix nitrogen to the same extent. It is thus possible that varieties of rice could be selected on the basis of their ability to support non-symbiotic N fixation in their rhizosphere

  18. Quantification of diazotrophs bacteria isolated from cocoa soils (Theobroma cacao L., by the technique of Most Probable Number (MPN

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    Adriana Zulay Argüello Navarro

    2016-07-01

    Full Text Available The objective of this research was to quantify diazotrophic bacteria and compare physicochemically rhizospheric soils of three cocoa plantations (Theobroma cacao L. in Norte de Santander Department, Colombia; for which they were characterized, differing in cultivated area, agronomic management and crop age. From serial dilutions of the samples and using the technique of Most Probable Number (MPN, In semisolid culture media (NFb, JMV, LGI, JNFb, the diazotrophs were quantified, evaluating as positive the formation of a subsurface film in the medium contained in sealed vials; equal samples were sent to the Bioambiental laboratory (UNET for physicochemical analyzes. As a result, the evaluated samples showed deficiencies in the percentage of organic matter and elements such as Potassium, Phosphorus and Magnesium. Statistically highly significant differences in MPN were reported. The highest quantification of diazotrophs was reported in the Florilandia farm, which was characterized by drip irrigation. The highest quantification of diazotrophs was recorded in the media NFb and JMV, demonstrating a greater presence of the presumed genera Azospirillum sp. and Burkholderia sp. which are easily isolated from rhizospheric soils, unlike the genera Herbaspirillum sp. and Gluconacetobacter sp. which by their endophytic character tend to be less predominant in this type of samples. It is also concluded that the physicochemical characteristics of the soil, humidity and climatic relationships at the moment of sampling, condition the amount of root exudates and therefore are factors that conditioned the presence of diazotrophs in the samples.

  19. Effect of four growth-promoting rhizobacteria on crown blight caused by Phytophthora capsici in sweet pepper (Capsicum annuum

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    Carlos Ramírez

    2015-11-01

    Full Text Available Crown blight, caused by Phytophthora capsici, is the most important disease of pepper (Capsicum annuum in the world and causes great economic losses in Costa Rica. Alternatives to chemical control against this disease are crucial to prevent damage to human health and the environment. The antagonism of Plant-Growth-Promoting Rhizobacteria (PGPR on P. capsici, and its ability to reduce wilt in pepper plants were evaluated. PGPR strains previously isolated from sugarcane and rice were identified, using 16S RNA gene sequence, as Pseudomonas fluorescens PC4, Stenotrophomonas rhizophila PC9, Pseudomonas fragi PC11 and Azospirillum lipoferum PCJ2. The inhibition of P. capcisi growth was evaluated in vitro, in the presence of the PGPR. The effect of the four bacterial strains on pepper plants inoculated with P. capsici (100 zoospores.plant-1 was evaluated in the greenhouse. P. fluorescens PC4, S. rhizophila PC9 and A. lipoferum PCJ2, inhibited in vitro growth of the oomycete by 54%, 30% and 50 % respectively, while S. rhizophila PC9 increased by 14% shoot fresh weight of pepper plants at the greenhouse. Furthermore, PCJ2 and PC9 strains reduced the shoot and root severity of the disease, and PCJ2-inoculated plants showed no symptoms at all, indicating that PC9 and PCJ2 are promising rizobacteria for the control of crown blight in pepper.

  20. The Effects of Gliricidia-Derived Biochar on Sequential Maize and Bean Farming

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    Ana Castro

    2018-02-01

    Full Text Available The addition of biochar to soils can improve soil fertility and increase agricultural productivity. We carried out a field experiment in which biochar produced from Gliricidia sepium (Jacq. Kunth ex Walp. was added to low-fertility Brazilian planosol and tested to increase the yield of maize (Zea mays and snap beans (Phaseolus vulgaris L. in sequential, organic cultivation. Biochar was applied at a 15 t/ha rate, combined or not with Azospirillum Brasiliense inoculation and organic fertilizer (Bokashi. The application of biochar resulted in an increase in soil pH and of the content of macronutrients such as phosphorus and potassium. Contrary to evidence from elsewhere, biochar had a limited effect on increasing maize yield. In the case of beans, when combined with fertilizer, biochar increased the production of beans pods and biomass, but the significant increase was observed only for inoculation. Beans are the principal component of Brazilian diet and increasing productivity of beans is of upmost importance for the poorest in Brazil, and in other tropical countries.

  1. Nutrient uptake of NPK and result of some rice varieties in tidal land by using combination of organic and inorganic fertilizer

    Science.gov (United States)

    Marlina, Neni; Rompas, Joni Phillep; Marlina, Musbik

    2017-09-01

    Rice planting in tidal land has two main problems: iron (Fe) which has the potential to poison rice and low nutrient availability. Azospirillum enriched chicken manure and phosphate solvent bacteria (Biological Organic Fertilizer = BOF) is an option to overcome iron toxicity and as a source of nutrition. The objective of the study was to obtain a combination of biological organic fertilizers and balanced inorganic fertilizers in reducing doses of inorganic fertilizers, increasing NPK nutrient uptake and yield of several rice varieties in tidal land. This research used Factorial RAK with 25 treatment combinations that were repeated three times. Factor I is a combination of BOF and anorganic fertilizer with 5 levels of treatment (no inorganic fertilizers, BOF 400 kg / ha with inorganic fertilizer 25% NPK, BOF 400 kg / ha with inorganic fertilizer 50% NPK and BOF 400 kg / ha with fertilizer Inorganic 75% NPK). Factor II is several rice varieties (IPB 4S, Martapura, Margasari, Inpara 5, Inpara 7). The results showed that organic fertilizer 400 kg / ha can reduce the use of inorganic fertilizer by 75% of NPK fertilizer. The highest NPK nutrient absorption is in the treatment of organic fertilizer 400 kg / ha and inorganic fertilizer 25% of NPK fertilizer. Production of biological organic fertilizer 400 kg / ha with inorganic fertilizer 25% NPK and 4B IPB varieties 727.77% higher when compared with without the provision of organic fertilizer with Inpara 5 varieties.

  2. Microbial Products and Biofertilizers in Improving Growth and Productivity of Apple - a Review.

    Science.gov (United States)

    Mosa, Walid F A E; Sas-Paszt, Lidia; Frąc, Mateusz; Trzciński, Paweł

    2016-08-26

    The excessive use of mineral fertilizers causes many negative consequences for the environment as well as potentially dangerous effects of chemical residues in plant tissues on the health of human and animal consumers. Bio-fertilizers are formulations of beneficial microorganisms, which upon application can increase the availability of nutrients by their biological activity and help to improve soil health. Microbes involved in the formulation of bio-fertilizers not only mobilize N and P but mediate the process of producing crops and foods naturally. This method avoids the use of synthetic chemical fertilizers and genetically modified organisms to influence the growth of crops. In addition to their role in enhancing the growth of the plants, biofertilizers can act as biocontrol agents in the rhizosphere at the same time. Biofertilizers are very safe for human, animal and environment. The use of Azotobacter, Azospirillum, Pseudomonas, Acetobacter, Burkholderia, Bacillus, Paenibacillus and some members of the Enterobacteriaceae is gaining worldwide importance and acceptance and appears to be the trend for the future.

  3. Using 32 P to evaluation of bio fertilizers symbiotic efficiency in wheat

    International Nuclear Information System (INIS)

    Ardakani, M.R.; Majd, F.; Nourmohammadi, G.

    2004-01-01

    In order to study the symbiotic efficiency of bio fertilizers in wheat specially Azospirillam, Mycorrhizal and streptomyces, an experiment have been carried out for 2 years by using 32p in greenhouse condition. The results showed that number of till/plant dry weight and activity/plant were increased in concordance with the increase of phosphorus amount. In addition, the application of Mycorrhizal in comparison with its non-application resulted in significant increase in entire above-mentioned measured characteristics, but its efficiency reduced by increasing phosphorous.Moreover, it was proven that there was a negative antagonistic effect by Streptomyces on Mycorrhizal, so that in all examined characteristics in which these two microorganisms were simultaneously used, a significant decrease was observed. Otherwise, study on phosphorus and mycorrhizal at different levels applications showed that phosphorus usage amount (0.40g/pot), in comparison with its more usage(0.60g/pot) had better effects on mycorrhizal. Application of Streptomyces had no significant on the examined characteristics. However, when applying both mycorrhizal and streptomyces, because of the sensitivity of mycorrhizal to Streptomyces presence, a decrease effect was observed. Application of Azospirillum, Mycorrhizal and specially organic fertilizer (manure), had positive and significant effects on the many of the measured characters

  4. Endophytic Colonization and In Planta Nitrogen Fixation by a Herbaspirillum sp. Isolated from Wild Rice Species

    Science.gov (United States)

    Elbeltagy, Adel; Nishioka, Kiyo; Sato, Tadashi; Suzuki, Hisa; Ye, Bin; Hamada, Toru; Isawa, Tsuyoshi; Mitsui, Hisayuki; Minamisawa, Kiwamu

    2001-01-01

    Nitrogen-fixing bacteria were isolated from the stems of wild and cultivated rice on a modified Rennie medium. Based on 16S ribosomal DNA (rDNA) sequences, the diazotrophic isolates were phylogenetically close to four genera: Herbaspirillum, Ideonella, Enterobacter, and Azospirillum. Phenotypic properties and signature sequences of 16S rDNA indicated that three isolates (B65, B501, and B512) belong to the Herbaspirillum genus. To examine whether Herbaspirillum sp. strain B501 isolated from wild rice, Oryza officinalis, endophytically colonizes rice plants, the gfp gene encoding green fluorescent protein (GFP) was introduced into the bacteria. Observations by fluorescence stereomicroscopy showed that the GFP-tagged bacteria colonized shoots and seeds of aseptically grown seedlings of the original wild rice after inoculation of the seeds. Conversely, for cultivated rice Oryza sativa, no GFP fluorescence was observed for shoots and only weak signals were observed for seeds. Observations by fluorescence and electron microscopy revealed that Herbaspirillum sp. strain B501 colonized mainly intercellular spaces in the leaves of wild rice. Colony counts of surface-sterilized rice seedlings inoculated with the GFP-tagged bacteria indicated significantly more bacterial populations inside the original wild rice than in cultivated rice varieties. Moreover, after bacterial inoculation, in planta nitrogen fixation in young seedlings of wild rice, O. officinalis, was detected by the acetylene reduction and 15N2 gas incorporation assays. Therefore, we conclude that Herbaspirillum sp. strain B501 is a diazotrophic endophyte compatible with wild rice, particularly O. officinalis. PMID:11679357

  5. Land use type significantly affects microbial gene transcription in soil.

    Science.gov (United States)

    Nacke, Heiko; Fischer, Christiane; Thürmer, Andrea; Meinicke, Peter; Daniel, Rolf

    2014-05-01

    Soil microorganisms play an essential role in sustaining biogeochemical processes and cycling of nutrients across different land use types. To gain insights into microbial gene transcription in forest and grassland soil, we isolated mRNA from 32 sampling sites. After sequencing of generated complementary DNA (cDNA), a total of 5,824,229 sequences could be further analyzed. We were able to assign nonribosomal cDNA sequences to all three domains of life. A dominance of bacterial sequences, which were affiliated to 25 different phyla, was found. Bacterial groups capable of aromatic compound degradation such as Phenylobacterium and Burkholderia were detected in significantly higher relative abundance in forest soil than in grassland soil. Accordingly, KEGG pathway categories related to degradation of aromatic ring-containing molecules (e.g., benzoate degradation) were identified in high abundance within forest soil-derived metatranscriptomic datasets. The impact of land use type forest on community composition and activity is evidently to a high degree caused by the presence of wood breakdown products. Correspondingly, bacterial groups known to be involved in lignin degradation and containing ligninolytic genes such as Burkholderia, Bradyrhizobium, and Azospirillum exhibited increased transcriptional activity in forest soil. Higher solar radiation in grassland presumably induced increased transcription of photosynthesis-related genes within this land use type. This is in accordance with high abundance of photosynthetic organisms and plant-infecting viruses in grassland.

  6. Bacterial Communities Associated with the Lichen Symbiosis▿ †

    Science.gov (United States)

    Bates, Scott T.; Cropsey, Garrett W. G.; Caporaso, J. Gregory; Knight, Rob; Fierer, Noah

    2011-01-01

    Lichens are commonly described as a mutualistic symbiosis between fungi and “algae” (Chlorophyta or Cyanobacteria); however, they also have internal bacterial communities. Recent research suggests that lichen-associated microbes are an integral component of lichen thalli and that the classical view of this symbiotic relationship should be expanded to include bacteria. However, we still have a limited understanding of the phylogenetic structure of these communities and their variability across lichen species. To address these knowledge gaps, we used bar-coded pyrosequencing to survey the bacterial communities associated with lichens. Bacterial sequences obtained from four lichen species at multiple locations on rock outcrops suggested that each lichen species harbored a distinct community and that all communities were dominated by Alphaproteobacteria. Across all samples, we recovered numerous bacterial phylotypes that were closely related to sequences isolated from lichens in prior investigations, including those from a lichen-associated Rhizobiales lineage (LAR1; putative N2 fixers). LAR1-related phylotypes were relatively abundant and were found in all four lichen species, and many sequences closely related to other known N2 fixers (e.g., Azospirillum, Bradyrhizobium, and Frankia) were recovered. Our findings confirm the presence of highly structured bacterial communities within lichens and provide additional evidence that these bacteria may serve distinct functional roles within lichen symbioses. PMID:21169444

  7. The Effect Different Fertilizers, on Germination, Yield, of Vicia vilosa Roth

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    R Kamaei

    2015-09-01

    Full Text Available In order to study the interaction of germination, yield of Vicia vilosa Roth to use of biological fertilizer, chemical, and manure, an experiment was conducted as a randomized complete block design with three replications at Research greenhouse, Faculty of Agriculture, Ferdowsi University of Mashhad, Iran, in 2013-2014 growing season. The experimental treatments was included three kinds of bio fertilizers and their integration with each other and vermicompost and chemical fertilizer as following : 1- mycorhhizaarbuscular species Glomus mosseae+vermicompost2- mycorhhiza+Nitrocsin (included bacteries Azospirillum sp. and Azotobacter sp. 3- mycorhhiza arbuscular+ Rhizobium (Rhizobium sp. 4-mycorhhiza arbuscular + Chemical fertilizer NPK 5- mycorhhizaarbuscular (Glomus moseae 6-control. The results showed that, although the treatments has not significant effects on height of stem , it has significant effects on characteristics of root length colonization percent, number the root node, Root dry weight, soggy yield, yield dry and protein Percent. The results showed that the highest percent of root length colonization(76 percent, number the root node (20, Root dry weight (.94 g, soggy yield (1894.5 g m-2, yield dry (473.63 g m-2 and protein Percent (27.33 percent was gained in integrated mycorhhiza and nitrocsine treatment. On the basis of results, the integration of mycrhhoriza and biological rhizobium is suggested as the best fertilizer treatment for Vicia vilosa Roth.

  8. Isolation and Characterization of Diazotrophic Rhizobacteria of Oil Palm Roots

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    Azlin, C. O.

    2005-01-01

    Full Text Available Beneficial rhizobacteria were isolated from two different compartments of oil palm roots; the rhizosphere or rhizoplane and the inner root tissues. The root samples were collected from oil palm plantation at Felda Lepar 9, Temerloh Pahang (Block 17, Square 6 (soil pH 4.30; 10:25 0.01M CaCl2. Identification of the isolates was conducted by classical biochemical and physiological tests. Acetylene Reduction Assay (ARA test was also conducted to quantify the ability of the isolates to fix atmospheric N2. Twenty-nine strains of rhizobacteria were isolated from root samples and were maintained aerobically on N-free solid media. Seven of the isolates were identified as Gram negative while the rest were Gram positive. The isolates were successfully identified as Paenibacillus durus (formerly P. azotofixans, Paenibacillus polymyxa, Azospirillum lipoferum, Herbaspirillum seropedicae and Acetobacter diazotrophicus. The N2 fixation capacities of the isolates ranged from 7.0 x 10-12 to 1.0 x 10-8 mol C2H4/cfu/hour.

  9. Organic and mineral fertilization of squash plant with application of 1'5N staple isotope

    International Nuclear Information System (INIS)

    El-Sherbiny, A.E.; Dahdouh, S.M.; Galal, Y.G.M.; Habib, A.A.M.

    2012-01-01

    A field experiment was conducted on virgin sand soil under drip irrigation system using squash fertilized with ammonium sulfate fertilizer, commercial compost locally manufactured in Egypt and artificial compost prepared fertilizer were applied either completely (100%) of mineral or of organic; or 50%: 50% (mineral: organic) by the authors at the Atomic Energy Authority of Egypt. All fertilization treatments were either inoculated or not inoculated with Azospirillum. Inoculation increased roots fresh weight. This was more pronounced with application of 50% mineral fertilizer plus 50% commercial compost, 100% artificial compost and 100% commercial compost. Similar trends, but to high extent were noticed with shoot fresh weight as affected by microbial inoculation and different organic composts. The 50%: 50% treatments as well as 100% artificial compost treatment gave high root and shoot dry weights. Inoculation and 50%: 50% fertilization treatments were more effective on N uptake. Higher N uptake was by shoots than roots. Portion and absolute value of N derived by roots from mineral fertilizer were significantly affected by combined fertilization treatments. Nitrogen derived from air (Ndfa) was positively affected by addition of organic compost and bacterial inoculation. Reversible trend was noticed with N derived from soil (Ndfa) which decreased when treated with compost and bacterial inoculation. All measurements were high in shoots than roots

  10. PERTUMBUHAN DAN PRODUKSI PADI SAWAH DAN GOGO DENGAN PEMBERIAN PUPUK HAYATI BERBASIS BAKTERI PEMACU TUMBUH DI TANAH MASAM

    Directory of Open Access Journals (Sweden)

    Arie Aryanto

    2015-12-01

    Full Text Available Biofertilizer is a substance which contains microorganism and promotes plant growth by increasing the soil nutrient availability. The aim of this study was to analyze the growth and production of lowland and upland rice by using the biofertilizer in acid soils. Seven isolates of bacteria were used as biofertilizer, i.e. Bacillus sp., two strains of Pseudomonas sp., two strains of Azospirillum sp., and two strains of Azotobacter sp.. The treatments of this study were without fertilization, compost, 100% NPK, compost enriched with 7 isolates, compost enriched with 7 isolates + 50% NPK, compost enriched with 4 isolates, and compost enriched with 4 isolates + 50% NPK. The results showed that biofertilizer in compost improved nutrient content in acid soil, and increased rice growth and production as well. Compost enriched with 7 isolates 50% NPK showed the highest rice yield production both in the lowland and upland rice. The biofertilizer could reduced 50% utilization NPK fertilizer dosage in the first growing season.

  11. Interaction of rhizosphere bacteria, fertilizer, and vesicular-arbuscular mycorrhizal fungi with sea oats.

    Science.gov (United States)

    Will, M E; Sylvia, D M

    1990-07-01

    Plants must be established quickly on replenished beaches in order to stabilize the sand and begin the dune-building process. The objective of this research was to determine whether inoculation of sea oats (Uniola paniculata L.) with bacteria (indigenous rhizosphere bacteria and N(2) fixers) alone or in combination with vesicular-arbuscular mycorrhizal fungi would enhance plant growth in beach sand. At two fertilizer-N levels, Klebsiella pneumoniae and two Azospirillum spp. did not provide the plants with fixed atmospheric N; however, K. pneumoniae increased root and shoot growth. When a sparingly soluble P source (CaHPO(4)) was added to two sands, K. pneumoniae increased plant growth in sand with a high P content. The phosphorus content of shoots was not affected by bacterial inoculation, indicating that a mechanism other than bacterially enhanced P availability to plants was responsible for the growth increases. When sea oats were inoculated with either K. pneumoniae or Acaligenes denitrificans and a mixed Glomus inoculum, there was no consistent evidence of a synergistic effect on plant growth. Nonetheless, bacterial inoculation increased root colonization by vesicular-arbuscular mycorrhizal fungi when the fungal inoculum consisted of colonized roots but had no effect on colonization when the inoculum consisted of spores alone. K. pneumoniae was found to increase spore germination and hyphal growth of Glomus deserticola compared with the control. The use of bacterial inoculants to enhance establishment of pioneer dune plants warrants further study.

  12. Simultaneous efficient removal of oxyfluorfen with electricity generation in a microbial fuel cell and its microbial community analysis.

    Science.gov (United States)

    Zhang, Qinghua; Zhang, Lei; Wang, Han; Jiang, Qinrui; Zhu, Xiaoyu

    2018-02-01

    The performance of a microbial fuel cell (MFC) to degrade oxyfluorfen was investigated. Approximately 77% of 50 mg/L oxyfluorfen was degraded within 24 h by anodic biofilm. The temperature, pH, and initial oxyfluorfen concentration had a significant effect on oxyfluorfen degrading, and a maximum degradation rate of 94.95% could theoretically be achieved at 31.96 °C, a pH of 7.65, and an initial oxyfluorfen concentration of 120.05 mg/L. Oxyfluorfen was further catabolized through various microbial metabolism pathways. Moreover, the anodic biofilm exhibited multiple catabolic capacities to 4-nitrophenol, chloramphenicol, pyraclostrobin, and sulfamethoxazole. Microbial community analysis indicated that functional bacteria Arcobacter, Acinetobacter, Azospirillum, Azonexus, and Comamonas were the predominant genera in the anodic biofilm. In terms of the efficient removal of various organic compounds and energy recovery, the MFC seemed to be a promising approach for the treatment of environmental contaminants. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. Relevance of various nitrogen fixing microorganisms in ecology and plant productivity as a basis for evaluating their damage by environmental chemicals

    Energy Technology Data Exchange (ETDEWEB)

    Jagnow, G

    1981-01-01

    To evaluate detrimental side-effects of environmental chemicals on the biological N/sub 2/-fixation the relative importance of the N/sub 2/-fixation of legume and non-legume root nodules, of symbiotic and free living blue-green algae, of aerobic and facultatively anaerobic rhizosphere bacteria and of anaerobic bacteria is discussed on the basis of their fixation rate and their contribution to the conservation of ecosystems. From an agricultural and ecological point of view the symbiotic N/sub 2/-fixation of legumes and non-legumes takes the first place, being followed by that of blue-green algae and rhizosphere bacteria. Compared with these, the strictly anaerobic N/sub 2/-fixation has only a minor importance. Variable side-effects of herbicides on N/sub 2/-fixing bacteria are cited to stress the necessity of testing representatives of various ecological groups. Suitable test systems are proposed with soybeans, white clover, Rhizobium cultures, N/sub 2/-fixing blue-green algae and with Azospirillum species.

  14. Endophytes in commercial micropropagation - friend or foe?

    Directory of Open Access Journals (Sweden)

    Rödel, Philipp

    2016-07-01

    Full Text Available Medicinal and aromatic plants are superorganisms like all plant species- naturally colonized by bacteria, fungi and protists. Micropropagated plants are facing different challenges under in vitro and ex vitro conditions: Mixotrophic growth under low light conditions on artificial nutrient media, poor gas exchange in small vessels, abiotic stress, bad rooting, transplanting stress, low survival rate during acclimatization in greenhouse. The use of endophytes in micropropagation can improve plant growth, yield, and health and induce tolerance to abiotic and biotic stress. A tool for the use of competent endophytes in micropropagation under in vitro and ex vitro conditions is “biotization” of plantlets with useful bacterial and fungal inocula. Fungal inocula which are used commercially are e.g. arbuscular mycorrhizal fungi in form of spores and extraradical mycelium on different carrier materials like expanded clay, vermiculite, sand or peat. Furthermore representatives of the root fungal genus Trichoderma are applied as spores formulated in powder. Plantgrowth promoting rhizobacteria of the important genera Bacillus, Pseudomonas, Azospirillum and Azotobacter in form of lyophilised endospores/bacterial cells in powder or liquid formulation are also available on the market.

  15. Fluctuation of microbial activities after influent load variations in a full-scale SBR. Recovery of the biomass after starvation

    Energy Technology Data Exchange (ETDEWEB)

    Cabezas, Angela; Draper, Patricia; Etchebehere, Claudia [Universidad de la Republica, Montevideo (Uruguay). Catedra de Microbiologia, Facultad de Quimica y Facultad de Ciencias

    2009-10-15

    Due to variations in the production levels, a full-scale sequencing batch reactor (SBR) for post-treatment of tannery wastewater was exposed to low and high ammonia load periods. In order to study how these changes affected the N-removal capacity, the microbiology of the reactor was studied by a diverse set of techniques including molecular tools, activity tests, and microbial counts in samples taken along 3 years. The recover capacity of the biomass was also studied in a lab-scale reactor operated with intermittent aeration without feeding for 36 days. The results showed that changes in the feeding negatively affected the nitrifying community, but the nitrogen removal efficiencies could be restored after the concentration stress. Species substitution was observed within the nitrifying bacteria, Nitrosomonas europaea and Nitrobacter predominated initially, and after an ammonia overload period, Nitrosomonas nitrosa and Nitrospira became dominant. Some denitrifiers, with nirS related to Alicycliphilus, Azospirillum, and Marinobacter nirS, persisted during long-term reactor operation, but the community fluctuated both in composition and in abundance. This fluctuating community may better resist the continuous changes in the feeding regime. Our results showed that a nitrifying-denitrifying SBR could be operated with low loads or even without feeding during production shut down periods. (orig.)

  16. Atividade antioxidante de frutas do cerrado Antioxidant activity of cerrado fruits

    Directory of Open Access Journals (Sweden)

    Roberta Roesler

    2007-03-01

    Full Text Available Annona crassiflora (araticum, Solanum lycocarpum (lobeira, Eugenia dysenterica (cagaita, Caryocar brasilense (pequi e Swartzia langsdorfii (banha de galinha são frutas do bioma cerrado, conhecidas e consumidas principalmente por populações nativas dessa região. Nesse estudo, as diferentes frações dos frutos acima descritos (polpa, semente e casca foram avaliadas por meio de extratos aquosos e etanólicos. Alguns extratos mostraram altíssimos conteúdos de compostos fenólicos e foram escolhidos para avaliação do potencial em seqüestrar radicais livres por meio do modelo 2,2 difenil-1-picril hidrazil (DPPH. Os melhores resultados foram: extrato aquoso e etanólico de casca de pequi (IC50 igual a 9,44 e 17,98 µg.mL-1 respectivamente, extrato etanólico de sementes de cagaita (IC50 igual a 14,15 µg.mL-1, extrato etanólico de sementes e casca de araticum (IC50 igual a 30,97 e 49,18 µg.mL-1, respectivamente. Este é o primeiro estudo que avalia o potencial em seqüestrar radicais livres de frações de frutas do cerrado. Os resultados indicam que os extratos possuem grande potencial antioxidante e estudos adicionais são necessários para avaliar essa propriedade dos extratos como uma aplicação sustentável dos recursos do cerrado nos setores farmacêuticos, cosméticos e nutricionais.Annona crassiflora (araticum, Solanum lycocarpum (lobeira, Eugenia dysenterica (cagaita, Caryocar brasilense (pequi and Swartzia langsdorfii (banha de galinha are tropical fruits consumed mainly by native people in the Brazilian Cerrado (second biggest biome of Brazil. In this study, pulp, seed and peel of the fruits were extracted using ethanol and water. Some of the extracts showed a high content of total phenols and were screened for their potential as antioxidants using the in vitro model 2,2-diphenyl-1-picryl hydrazyl (DPPH. The best results were found for aqueous and ethanolic extracts of pequi peel (IC50 of 9,44 and 17,98 µg.mL-1 respectively

  17. Ocorrência de bactérias diazotróficas e fungos micorrízicos arbusculares na cultura da mandioca Occurrence of diazotrophic bacteria and arbuscular mycorrhizal fungi on the cassava crop

    Directory of Open Access Journals (Sweden)

    Elcio Liborio Balota

    1999-07-01

    Full Text Available Este trabalho teve como objetivo avaliar a ocorrência, isolar e identificar fungos micorrízicos arbusculares associados à cultura da mandioca (Manihot esculenta. Amostras de solo rizosférico e de várias partes da planta (raízes, tubérculos, manivas e folhas de locais nos Estados do Rio de Janeiro, São Paulo e Paraná, foram inoculadas nos meios LGI-P, NFb-malato e NFb-GOC, avaliando-se o número mais provável de células e a atividade de redução de acetileno. Bactérias diazotróficas foram isoladas de todas as partes da planta, com exceção das folhas, sendo identificadas como Klebsiella sp., Azospirillum lipoferum e uma bactéria denominada "E", provavelmente pertencente ao gênero Burkholderia. A Bactéria E acumulou de 7,63 mg a 14,84 mg de N/g de C em meio semi-sólido, isento de N, e conseguiu manter a capacidade de fixação biológica de N, mesmo após uma dezena de repicagens consecutivas. A colonização micorrízica variou de 31% a 69%, e a densidade de esporos de 10 a 384 esporos/100 mL de solo, predominando as espécies Entrophospora colombiana e Acaulospora scrobiculata no Rio de Janeiro, A. scrobiculata e Scutellospora heterogama no Paraná e em Piracicaba (São Paulo e A. appendicula e S. pellucida em Campinas (São Paulo.This study was performed to evaluate the occurrence and to isolate and identify diazotrophic bacteria and arbuscular mycorrhizal fungi associated with the cassava (Manihot esculenta crop. Samples from rhizospherical soil, roots, tubers, stems and leaves from several localities of the States of Rio de Janeiro, São Paulo and Paraná, in Brazil, were inoculated in three media specific for diazotrophic associative bacteria, LGI-P, NFb-malate and NFb-GOC, evaluating the most probable number of cells and the acetylene-reducing activity. Diazotrophic bacteria were detected in all plant parts except for the leaves, and were identified as Klebsiella sp., Azospirillum lipoferum and a bacterium called "E

  18. Ocorrência e efeito de bactérias diazotróficas em genótipos de trigo Occurrence and effect of diazotrophic bacteria in wheat genotypes

    Directory of Open Access Journals (Sweden)

    Valéria Marino Rodrigues Sala

    2005-06-01

    Full Text Available A pesquisa sobre bactérias diazotróficas na cultura do trigo tem demonstrado a necessidade de associar bactérias eficientes a genótipos promissores, os quais se beneficiariam dessa associação. Em um experimento com parcelas subdivididas, instalado em condições de campo, em Mococa (SP, empregando os tratamentos: três doses de N (0, 60 e 120 kg ha-1 e três genótipos de trigo (IAC-24, ITD-19 e IAC-355, foi avaliada a ocorrência de microrganismos diazotróficos endofíticos em raízes desinfestadas superficialmente, utilizando-se três meios de cultivo distintos, NFb, JNFb e LGI-P. Somente para o genótipo IAC-355, houve um ajuste linear ascendente da quantidade de bactérias diazotróficas com o aumento na quantidade de N adicionada, apesar de o mesmo genótipo apresentar o menor número de bactérias diazotróficas endofíticas nos três meios de cultivo utilizados para quantificação. Foram obtidos oito isolados bacterianos do meio NFb com as características de Azospirillum e doze do meio JNFb com as características de Herbaspirillum. Esses isolados foram testados "in vitro", nos genótipos dos quais foram originalmente isolados, ou seja, ITD-19 e IAC-24. Todos os isolados testados no genótipo ITD-19 causaram maior crescimento radicular que a testemunha e apenas um isolado do meio JNFb propiciou aumento significativo do N acumulado na parte aérea. A interação planta-bactéria diazotrófica associativa indicou que é possível obter benefícios desta associação.Research on wheat root diazotrophic bacteria has demonstrated the need to associate effective bacteria to promising genotypes, which would benefit from this association. A field experiment was carried out in Mococa County, State of São Paulo, Brazil, using a split-plot design. Treatments consisted of 3 wheat genotypes (IAC-24, ITD-19 and IAC-355 under 3 nitrogen doses (0, 60 and 120 kg ha-1. The occurrence of diazotrophic bacteria was evaluated in three growth media

  19. Endolithic microbial communities in carbonate precipitates from serpentinite-hosted hyperalkaline springs of the Voltri Massif (Ligurian Alps, Northern Italy).

    Science.gov (United States)

    Quéméneur, Marianne; Palvadeau, Alexandra; Postec, Anne; Monnin, Christophe; Chavagnac, Valérie; Ollivier, Bernard; Erauso, Gaël

    2015-09-01

    The Voltri Massif is an ophiolitic complex located in the Ligurian Alps close to the city of Genova (Northern Italy) where several springs discharge high pH (up to 11.7), low salinity waters produced by the active serpentinization of the ultramafic basement. Mixing of these hyperalkaline waters with the river waters along with the uptake of atmospheric carbon dioxide forms brownish carbonate precipitates covering the bedrock at the springs. Diverse archaeal and bacterial communities were detected in these carbonate precipitates using 454 pyrosequencing analyses of 16S ribosomal RNA (rRNA) genes. Archaeal communities were dominated by members of potential methane-producing and/or methane-oxidizing Methanobacteriales and Methanosarcinales (Euryarchaeota) together with ammonia-oxidizing Nitrososphaerales (Thaumarchaeota) similar to those found in other serpentinization-driven submarine and terrestrial ecosystems. Bacterial communities consisted of members of the Proteobacteria, Actinobacteria, Planctomycetes, Bacteroidetes, Chloroflexi, and Verrucomicrobia phyla, altogether accounting for 92.2% of total retrieved bacterial 16S rRNA gene sequences. Amongst Bacteria, potential chemolithotrophy was mainly associated with Alpha- and Betaproteobacteria classes, including nitrogen-fixing, methane-oxidizing or hydrogen-oxidizing representatives of the genera Azospirillum, Methylosinus, and Hydrogenophaga/'Serpentinomonas', respectively. Besides, potential chemoorganotrophy was attributed mainly to representatives of Actinobacteria and Planctomycetales phyla. The reported 16S rRNA gene data strongly suggested that hydrogen, methane, and nitrogen-based chemolithotrophy can sustain growth of the microbial communities inhabiting the carbonate precipitates in the hyperalkaline springs of the Voltri Massif, similarly to what was previously observed in other serpentinite-hosted ecosystems.

  20. Ocorrência de bactérias diazotróficas e fungos micorrízicos arbusculares na cultura da mandioca

    Directory of Open Access Journals (Sweden)

    Elcio Liborio Balota

    1999-07-01

    Full Text Available Este trabalho teve como objetivo avaliar a ocorrência, isolar e identificar fungos micorrízicos arbusculares associados à cultura da mandioca (Manihot esculenta. Amostras de solo rizosférico e de várias partes da planta (raízes, tubérculos, manivas e folhas de locais nos Estados do Rio de Janeiro, São Paulo e Paraná, foram inoculadas nos meios LGI-P, NFb-malato e NFb-GOC, avaliando-se o número mais provável de células e a atividade de redução de acetileno. Bactérias diazotróficas foram isoladas de todas as partes da planta, com exceção das folhas, sendo identificadas como Klebsiella sp., Azospirillum lipoferum e uma bactéria denominada "E", provavelmente pertencente ao gênero Burkholderia. A Bactéria E acumulou de 7,63 mg a 14,84 mg de N/g de C em meio semi-sólido, isento de N, e conseguiu manter a capacidade de fixação biológica de N, mesmo após uma dezena de repicagens consecutivas. A colonização micorrízica variou de 31% a 69%, e a densidade de esporos de 10 a 384 esporos/100 mL de solo, predominando as espécies Entrophospora colombiana e Acaulospora scrobiculata no Rio de Janeiro, A. scrobiculata e Scutellospora heterogama no Paraná e em Piracicaba (São Paulo e A. appendicula e S. pellucida em Campinas (São Paulo.

  1. Agronomic efficiency INIAP-17 rice with levels of chemical and biological fertilization in Ecuadorian Coast

    Directory of Open Access Journals (Sweden)

    Eduardo Neptali Colina Navarrete

    2017-05-01

    Full Text Available The investigation was carried out in the experimental farm of the College of Agricultural Sciences of the Technical University of Babahoyo, canton Babahoyo. Ten treatments were evaluated with three repetitions. The objective was to analyze the influence of four organic bioestimulantes on the efficiency of the conventional chemical fertilization in rice (Oryza sativa, to measure the effect on the agronomic behavior of the cultivation. The variety of rice INIAP-17 was sowed in parcels of 20 m2. The treatments were distributed at random in a design of complete blocks. For the evaluation of stockings the test was used from Tukey to significancia 5%. At the end of the cycle of the cultivation was evaluated: height of plants, sprout number for m2, grains for panicles, length and number of panicles m2, days to flowering, days to crop, number of grains for panicles, weight 1000 grains and yield for hectare. The results determined that the application of a program of high fertilization level (140-60-90-30 kg/ha, of N-P-K-S + Azospirillum 3 L/ha, the grain yield increased with increments of 23,44% with relationship to the witness. In the same way applications of Bacilllus and Azotobacter more levels means (120-40-60-20 and first floor (100-30-40-10 of application of N-P-K-S, they don't impact in days to the flowering, tipping, weight of 1000 grains, number of grains for panicles and relationship grain/straw.

  2. IMPACTO DE INOCULACIÓN CON LA BACTERIA NATIVA AzospirilumSOBRE Oryza sativa L. EN CÓRDOBA-COLOMBIA

    Directory of Open Access Journals (Sweden)

    CECILIA LARA M

    2013-12-01

    Full Text Available Se evaluó el efecto en el crecimiento y desarrollo de plantas de arroz Paddy,Oryzasativa L. variedad comercial FEDEARROZ 733, inoculado con la cepa nativa Azospirillum(A5, comparado con un testigo absoluto y un testigo comercial (Urea. Se realizó la multiplicación delabacteria a diferentes concentraciones: 106, 107 y 108 UFC, en el medio de cultivo NFB líquido a 24°C, agitación constante e incubación por 72 horas. El estudio se realizó bajo condiciones de invernadero con suelo con bajo contenido de materia orgánica; las semillas fueron embebidas en las diferentes concentraciones bacterianas. Se utilizó un diseño en bloques completos al azar con tres repeticiones y cinco tratamientos: testigo absoluto, testigo comercial y las concentraciones bacterianas 106,107 y 108 UFC. Se evaluaron las variables altura de planta, longitud de las raíces, número de macollas planta y peso seco/planta, a los 30, 60, 90 y 120 días después de germinación. El número de panículas/planta, número de granos/planta y el rendimiento en granos se midieron al momento de la cosecha. La concentración107 UFC produjo 3,74 g/planta; éste valor fue similar al obtenido utilizando fertilizante nitrogenado, demostrándose que las inoculaciones influyen en el crecimiento y producción de las plantas de arroz.

  3. Characterization of N2-fixing plant growth promoting endophytic and epiphytic bacterial community of Indian cultivated and wild rice (Oryza spp.) genotypes.

    Science.gov (United States)

    Banik, Avishek; Mukhopadhaya, Subhra Kanti; Dangar, Tushar Kanti

    2016-03-01

    The diversity of endophytic and epiphytic diazotrophs in different parts of rice plants has specificity to the niche (i.e. leaf, stem and root) of different genotypes and nutrient availability of the organ. Inoculation of the indigenous, polyvalent diazotrophs can facilitate and sustain production of non-leguminous crops like rice. Therefore, N2-fixing plant growth promoting bacteria (PGPB) were isolated from different parts of three Indian cultivated [Oryza sativa L. var. Sabita (semi deep/deep water)/Swarna (rain fed shallow lowland)/Swarna-Sub1(submergence tolerant)] and a wild (O. eichingeri) rice genotypes which respond differentially to nitrogenous fertilizers. Thirty-five isolates from four rice genotypes were categorized based on acetylene reduction assay on nitrogenase activity, biochemical tests, BIOLOG and 16S rRNA gene sequencing. The bacteria produced 9.36-155.83 nmole C2H4 mg(-1) dry bacteria h(-1) and among them nitrogenase activity of 11 potent isolates was complemented by nifH-sequence analysis. Phylogenetic analysis based on 16S rDNA sequencing divided them into five groups (shared 95-100 % sequence homology with type strains) belonging to five classes-alpha (Ancylobacter, Azorhizobium, Azospirillum, Rhizobium, Bradyrhizobium, Sinorhizobium, Novosphingobium, spp.), beta (Burkholderia sp.), gamma (Acinetobacter, Aeromonas, Azotobacter, Enterobacter, Klebsiella, Pantoea, Pseudomonas, Stenotrophomonas spp.) Proteobacteria, Bacilli (Bacillus, Paenibacillus spp.) and Actinobacteria (Microbacterium sp.). Besides, all bacterial strains possessed the intrinsic PGP traits of like indole (0.44-7.4 µg ml(-1)), ammonia (0.18-6 mmol ml(-1)), nitrite (0.01-3.4 mol ml(-1)), and siderophore (from 0.16-0.57 μmol ml(-1)) production. Inoculation of rice (cv. Swarna) seedlings with selected isolates had a positive impact on plant growth parameters like shoot and root elongation which was correlated with in vitro PGP attributes. The results indicated that the

  4. Effect of Bioremediation on Growth of Wheat Plant Cultivated In Contaminated Soil with Heavy Metals

    International Nuclear Information System (INIS)

    Abdel-Azis, O.A.; El-Ghandour, I.A.; Galal, Y.G.M.; El-Sheikh, H.H.

    2008-01-01

    Pot experiment was carried out under greenhouse conditions to evaluate the impact of BYFA (bacterial, fungal, yeast, and actinomycetes isolates), and bio fertilizers (mycorrhizas and N 2 fixers) in remedy the heavy metals -polluted soil and its effect on wheat growth. Basal recommended doses of P and N were applied; the treatments were arranged in completely randomized block design. The results showed a positive effect on growth and N uptake by wheat cultivated in polluted soil with (Zn, Cu, Pb, Co, Ni and Cd). The data cleared that, the lowest content of Pb in the soil was occurred with composite inoculants plus BFYA (274.57μ g/gm) as compared to the other treatments. Reduction in zinc content in soil was recorded with control + BFYA (272.0 μg/g) compared to other one. Similarly, inoculation with (Azo) + (BFYA) induced a reduction in Cu content in soil, Data of 15 N revealed that both the mechanisms of BNF have been occurred. In this respect, it is worthy to mention that, symbiotic bacteria has a considerable role with such cereal crop via BNF or enhancement of plant growth, The inoculation with Rh + AM resulted in the highest percentage of N uptake from fertilizer (29%), followed by AM, then Azo (23.9%, 22.7%, respectively) without BFYA. Another picture was noticed with BFYA whereas the best percentage was recorded with Azospirillum (19.3 %). This treatment is the only one that increased the portion of N derived from fertilizer over those recorded with the control (11.13%). BFYA have the ability to reduce the content of heavy metal in both the contaminated soil and wheat plant. Similar function was detected with bio fertilizers, besides to their effects on enhancement of plant growth via plant growth promotion substances and BNF mechanisms

  5. Project in determination of crystal structure of nitrogen fixation proteins from azospirilum brasiliense and herbaspirilum seropedicae by synchrotron x-ray diffraction

    International Nuclear Information System (INIS)

    Barbosa, Valma M.; Leggs, Luciana A.; Delboni, Luis F.; Chubatsu, LedaS.; Souza, Emanuel M.; Machado, Hidevaldo B.; Yates, Geoffrey M.; Pedrosa, Fabio O.

    1996-01-01

    Full text. Biological nitrogen fixation is essential for maintaining the nitrogen cycle on earth and of high importance for Brazilian agriculture. The nitrogenase enzyme system, which provides the biochemical machinery for nitrogen fixation, consists of two component metalloproteins, the molybdenumiron (Mo Fe) protein and the iron (Fe) protein. Nitrogen fixation is a very energy-intensive process, requiring around 16 moles of ATP for each mol of N 2 fixed (reduced). As a consequence, synthesis and activity of nitrogenase is tighty regulated at two levels: general and specific. The general level regulation is mediated by the ntr (nitrogen regulation) system. Two gene products are involved: the ntrB gene product (NtrB) is responsible for the activation of the ntrC gene product (NtrC) by phosphorylating a conserved Asp54, which activates the expression of the nifA gene. The nif specific control system is mediated by the NifA protein, which binds to a DNA specific sequence (UAS, Upstream Activator Sequence) and activates nif promoter transcriptions by RNA polymerase- α54 , following ATP hydrolysis. The aim of this project is to solve the crystal structure of dinitrogenase reductase (iron protein) and dinitrogenase (molybdenum-iron protein) from Azospirilim brasiliense and the regulatory proteins NifA from Herbaspirillum seropedicae and NtrC Azospirillum brasiliense. The three dimensional structure of the proteins involved in this project will allow a better understanding of the mechanism of biological nitrogen fixation. To this end, the data collection will probably be done at the LNLS facilities which will be available in the near future. (author)

  6. High diversity of nitrogen-fixing bacteria in upper reaches of Heihe River, Northwestern China

    Science.gov (United States)

    Tai, X. S.; Mao, W. L.; Liu, G. X.; Chen, T.; Zhang, W.; Wu, X. K.; Long, H. Z.; Zhang, B. G.

    2013-03-01

    Vegetation plays a key role to water conservation in southern Qilian Mountains (Northwestern China), the upper reaches of Heihe River. Nitrogen-fixing bacteria are crucial for vegetation protection because they can supply plants with nitrogen source. Nevertheless, little is known about nitrogen-fixing bacteria in this region. In present study, nifH gene clone libraries were established for detecting the difference of nitrogen-fixing bacterial communities between Potentilla parvifolia shrub and Carex alrofusca meadow in the southern Qilian Mountains. All the identified nitrogen-fixing bacterial clones belonged to Proteobacteria. At the genus level, the Azospirillum sp. was only detected in shrub soil while Thiocapsa sp., Derxiasp., Ectothiorhodospira sp., Mesorhizobium sp., Klebsiella sp., Ensifer sp., Methylocella sp. and Peseudomonas sp. were just detected in meadow soil. Shannon-Wiener index of nifH gene ranged from 1.5 to 2.8 and was higher in meadow soil than shrub soil. Contrarily, the nifH gene copies and CFUs of cultured nitrogen-fixing bacteria ranged from 0.4 × 107 to 6.9 × 107 copies g-1 soil and 0.97 × 106 to 12.78 × 106 g-1 soil, respectively. Furthermore, both of them were lower in meadow soil than shrub soil. Statistical analysis revealed that diversity and copies of nifH gene mostly correlated with aboveground biomass in shrub soil. In meadow soil, nifH gene diversity was principally affected by altitude while copies did by soil available K.

  7. Nitrogen fixation by free-living organisms in rice soils. Studies with 15N

    International Nuclear Information System (INIS)

    Rao, V.R.; Charyulu, P.B.B.N.; Nayak, D.N.; Ramakrishna, C.

    1979-01-01

    Heterotrophic nitrogen fixation as influenced by water regime, organic matter, combined nitrogen and pesticides was investigated in several Indian rice soils by means of the 15 N 2 tracer technique. Soil submergence accelerated nitrogen fixation. Addition of cellulose to both non-flooded and flooded soils enhanced nitrogen fixation. Under submerged conditions, addition of sucrose, glucose and malate in that order stimulated nitrogen fixation in alluvial soil, while only sucrose enhanced nitrogen fixation in laterite soil. Nitrogen fixation in flooded alluvial and laterite soils decreased with increasing concentration of combined nitrogen. Nitrogen fixation was appreciable in acid sulphate and saline soils under both flooded and non-flooded conditions, despite high salinity and acidity. Application of certain pesticides at rates equivalent to recommended field level greatly influenced nitrogen fixation in flooded rice soils. Additions of benomyl (carbamate fungicide) and carbofuran (methyl carbamate insecticide) to alluvial and laterite soils resulted in significant stimulation of nitrogen fixation. Gamma-BHC stimulated nitrogen fixation only in alluvial soil, with considerable inhibition in a laterite soil. Nitrogen fixation by Azospirillum lipoferum was investigated by 15 N 2 . Large variations in 15 N 2 incorporation by A. lipoferum isolated from the roots of several rice cultivars was observed. Specific lines of rice harbouring A. lipoferum with high nitrogenase activity might be selected. Nitrogen fixed by heterotrophic organisms in a complex system such as soil could not be evaluated precisely. Indigenous nitrogen fixation in a flooded soil would be in the range of 5-10 kg N/ha, increasable 3 to 4-fold by appropriate fertilizers and cultural practices

  8. Prokaryotic Diversity in the Rhizosphere of Organic, Intensive, and Transitional Coffee Farms in Brazil.

    Science.gov (United States)

    Caldwell, Adam Collins; Silva, Lívia Carneiro Fidéles; da Silva, Cynthia Canêdo; Ouverney, Cleber Costa

    2015-01-01

    Despite a continuous rise in consumption of coffee over the past 60 years and recent studies showing positive benefits linked to human health, intensive coffee farming practices have been associated with environmental damage, risks to human health, and reductions in biodiversity. In contrast, organic farming has become an increasingly popular alternative, with both environmental and health benefits. This study aimed to characterize and determine the differences in the prokaryotic soil microbiology of three Brazilian coffee farms: one practicing intensive farming, one practicing organic farming, and one undergoing a transition from intensive to organic practices. Soil samples were collected from 20 coffee plant rhizospheres (soil directly influenced by the plant root exudates) and 10 control sites (soil 5 m away from the coffee plantation) at each of the three farms for a total of 90 samples. Profiling of 16S rRNA gene V4 regions revealed high levels of prokaryotic diversity in all three farms, with thousands of species level operational taxonomic units identified in each farm. Additionally, a statistically significant difference was found between each farm's coffee rhizosphere microbiome, as well as between coffee rhizosphere soils and control soils. Two groups of prokaryotes associated with the nitrogen cycle, the archaeal genus Candidatus Nitrososphaera and the bacterial order Rhizobiales were found to be abundant and statistically different in composition between the three farms and in inverse relationship to each other. Many of the nitrogen-fixing genera known to enhance plant growth were found in low numbers (e.g. Rhizobium, Agrobacter, Acetobacter, Rhodospirillum, Azospirillum), but the families in which they belong had some of the highest relative abundance in the dataset, suggesting many new groups may exist in these samples that can be further studied as potential plant growth-promoting bacteria to improve coffee production while diminishing negative

  9. Non-symbiotic bacterial diazotrophs from of agricultural crops of San Carlos. Córdoba, Colombia

    Directory of Open Access Journals (Sweden)

    Cecilia Lara Mantilla

    2007-07-01

    Full Text Available Diazotrophic Azotobacter sp and Azospirrillum sp bacteria were isolated from the rhizosphere of plantain, (Musa paradisiaca, corn, wheat and fallow areas (uncultivated, but covered by fallen leaves in the San Carlos region (in the Sinú valley in the Córdoba department, Colombia. Microbial populations were identified by biochemical tests; physiological characters were examined using Gram reaction in different mediums: Burk’s, Ashby and Jensen’s (Azotobacter sp and Burk’s, NFB and Congo-red medium (Azospirillum sp. The study was aimed at determining ion ammonium production from Azotobacter sp and Azospirrillum sp isolates; ion ammonium was quantified according to Berthelot’s colorimetric technique (phenol-hypochlorite. This method was modified and standardised in line with using a Perkin-Elmer Lamba 11 UV-Vis spectrometer. As a result of this study, 14 isolates have been shown to be ammonium-producers at concentrations ranging from 0.9 mg/l to 5.2 mg/l; A16PG (5.1545 mg/l and A26M1P (5.1743 mg/l yielded the highest ammonium concentrations for Azotobacter sp and A5M1G (4.6741 mg/l for Azospirrillum sp. Biological N2 fixation (BNF by associative diazotrophic bacteria has contributed towards increasing harvest yield, thereby reducing the need for nitrogenised fertilisers and the emission of greenhouse gases (such as N2O and obtaining economic and environmental benefits for farming.

  10. Study of qualitative and quantitative yield and some agronomic characteristics of sunflower (Helianthus annus L. in response of seed inoculation with PGPR in various levels of nitrogen fertilizer

    Directory of Open Access Journals (Sweden)

    H. Nazarly

    2016-05-01

    Full Text Available In order to study the qualitative and quantitative yield and some agronomic characteristics of sunflower (Helianthus annus L. in response to seed inoculation with PGPR under various levels of nitrogen fertilizer, a factorial experiment was conducted based on a randomized complete block design with three replications in field experimental University of Mohaghegh Ardabili during growing season of 2009-2010. Factors were nitrogen fertilizer in three levels (0, 80 and 160 kg N ha-1 as urea and seed inoculation with plant growth promoting rhizobacteria in four levels containing, without inoculation (as control, seed inoculation with Azotobacter chroococcum strain 5, Azospirillum lipoferum strain OF, Psedomunas strain 186. Results indicated that nitrogen levels and seed inoculation with Plant Growth Promoting Rhizobacteria (PGPR had significant effects on all of characteristics studied (except grain 1000 weight and stem diameter. Grain yield, plant height, head diameter, seed number per head, , yield and oil percentage, yield and protein percentage increased with increasing of nitrogen fertilizer and application of seed inoculation with PGPR. Response of grain yield wasn't the same for various levels of nitrogen fertilizer and seed inoculation with PGPR. The highest grain yield belonged to application of 160 kg N ha-1 and seed inoculation with Azotobacter. Means comparison showed that treatment compounds N160 × without inoculation with PGPR and N80 × seed inoculation with PGPR Azotobacter had similar grain yields. Thus, it can be suggested that in order to increasing of grain yield seed should be inoculated with Azotobacter bacteria × 80 kg N/ha in conditions of Ardabil region.

  11. Evaluation of terrestrial microcosms for assessing the fate and effects of genetically engineered microorganisms on ecological processes

    Energy Technology Data Exchange (ETDEWEB)

    Fredrickson, J.K.; Bentjen, S.A.; Bolton, H. Jr.; Li, S.W.; Ligotke, M.W.; McFadden, K.M.; Van Voris, P.

    1989-04-01

    This project evaluates and modifies the existing US Environmental Protection Agency's Office of Pesticides and Toxic Substances (EPA/OPTS) terrestrial microcosm test system and test protocols such that they can be used to determine the environmental fate and ecological hazards of genetically engineered microorganisms (GEMs). The intact soil-core microcosm represents terrestrial ecosystems, and when coupled with appropriate test protocols, such microcosms may be appropriate to define and limit risks associated with the intentional release of GEMs. The terrestrial microcosm test system was used to investigate the survival and transport of two model GEMs (Azospirillum lipoferum and Pseudomonas sp. Tn5 mutants) to various trophic levels and niches and through intact soil cores. Subsequent effects on nutrient cycling and displacement of indigenous microorganisms were evaluated. The model organisms were a diazotrophic root-colonizing bacterium (A. lipoferum) and a wheat root growth-inhibiting rhizobacterium (Pseudomonas sp.). The transposable element Tn5 was used as a genetic marker for both microorganisms in two separate experiments. The organisms were subjected to transposon mutagenesis using a broad host-range-mobilizable suicide plasmid. The transposon Tn5 conferred levels of kanamycin resistance up to 500 ..mu..g/ml (Pseudomonas sp.), which allowed for selection of the bacteria from environmental samples. The presence of Tn5 DNA in the genome of the model GEMs also allowed the use of Tn5 gene probes to confirm and enumerate the microorganisms in different samples from the microcosms. Two types of root growth-inhibiting Pseudomonas sp. Tn5 mutants were obtained and used in microcosm studies: those that lacked the ability to inhibit either wheat root growth or the growth of other microorganisms in vitro (tox/sup /minus//) and those which retained these properties (tox/sup +/). 53 refs., 7 figs., 6 tabs.

  12. Evaluation of terrestrial microcosms for detection, fate, and survival analysis of genetically engineered microorganisms and their recombinant genetic material

    Energy Technology Data Exchange (ETDEWEB)

    Fredrickson, J.K.; Seidler, R.J.

    1989-02-01

    The research included in this document represents the current scientific information available regarding the applicability of terrestrial microcosms and related methodologies for evaluating detection methods and the fate and survival of microorganisms in the environment. The three terrestrial microcosms described in this document were used to evaluate the survival and fate of recombinant bacteria in soils and in association with plant surfaces and insects and their transport through soil with percolating water and root systems, and to test new methods and procedures to improve detection and enumeration of bacteria in soil. Simple (potting soil composed of peat mix and perlite, lacking environmental control and monitoring) and complex microcosms (agricultural soil with partial control and monitoring of environmental conditions) were demonstrated to be useful tools for preliminary assessments of microbial viability in terrestrial ecosystems. These studies evaluated the survival patterns of Enterobacter cloacae (pBR322) in soil and on plant surfaces and the ingestion of this same microorganism by cutworms and survival in the foregut and frass. The Versacore microcosm design was used to monitor the fate and competitiveness of genetically engineered bacteria in soil. Both selective media and gene probes were used successfully to follow the fate of two recombinant Pseudomonas sp. introduced into Versacore microcosms. Intact soil-core microcosms were employed to evaluate the fate and transport of genetically altered Azospirillum sp. and Pseudomonas sp. in soil and the plant rhizosphere. The usefulness of these various microcosms as a tool for risk assessment is underscored by the ease in obtaining soil from a proposed field release site to evaluate subsequent GEM fate and survival.

  13. Effects of the inoculation of Burkholderia vietnamensis and related endophytic diazotrophic bacteria on grain yield of rice.

    Science.gov (United States)

    Govindarajan, Munusamy; Balandreau, Jacques; Kwon, Soon-Wo; Weon, Hang-Yeon; Lakshminarasimhan, Cunthipuram

    2008-01-01

    During a survey of endophytic diazotrophic bacteria associated with different rice varieties in Tamilnadu, some "endophytes" were obtained. Thirteen bacterial isolates from surface-sterilized roots and shoots were obtained in pure culture, which produced indole acetic acid (IAA) and reduced acetylene to ethylene. Polymerase chain reaction (PCR) amplification confirmed the presence of nif-H gene in all the isolates. Morphological, biochemical, and molecular characteristics indicated that all of them belonged to the genus Burkholderia One of them, MGK3, was consistently more active in reducing acetylene, and 16S rDNA sequences of isolate MGK3 confirmed its identification as Burkholderia vietnamiensis. Colonization of rice root was confirmed by strain MGK3 marked with gusA gene. The inoculated roots showed a blue color, which was most intense at the points of lateral root emergence and at the root tip. Transverse sections of roots, 15 days after inoculation, revealed beta-glucuronidase (GUS) activity within many of the cortical intercellular spaces next to the stele and within the aerenchyma. Nitrogen fixation was quantified by using (15)N isotope dilution method with two different cultivars grown in pot and field experiments. Higher nitrogen fixation was observed in variety Ponni than in ADT-43, where nearly 42% (field) and 40% (pot) of the nitrogen was derived from the atmosphere (% Ndfa). Isolate MGK3 was used to inoculate rice seedlings in a comparison with four other diazotrophs, viz., Gluconacetobacter diazotrophicus LMG7603, Herbaspirillum seropedicae LMG6513, Azospirillum lipoferum 4B LMG4348, and B. vietnamiensis LMG10929. They were used to conduct two pot and four field inoculation experiments. MGK3 alone, and combined with other diazotrophs, performed best under both pot and field conditions: combined inoculation produced yield increases between 9.5 and 23.6%, while MGK3 alone increased yield by 5.6 to 12.16% over the uninoculated control treatment.

  14. Plant-based culture media: Efficiently support culturing rhizobacteria and correctly mirror their in-situ diversity.

    Science.gov (United States)

    Youssef, Hanan H; Hamza, Mervat A; Fayez, Mohamed; Mourad, Elhussein F; Saleh, Mohamed Y; Sarhan, Mohamed S; Suker, Ragab M; Eltahlawy, Asmaa A; Nemr, Rahma A; El-Tahan, Mahmod; Ruppel, Silke; Hegazi, Nabil A

    2016-03-01

    Our previous publications and the data presented here provide evidences on the ability of plant-based culture media to optimize the cultivability of rhizobacteria and to support their recovery from plant-soil environments. Compared to the tested chemically-synthetic culture media (e.g. nutrient agar and N-deficient combined-carbon sources media), slurry homogenates, crude saps, juices and powders of cactus (Opuntia ficus-indica) and succulent plants (Aloe vera and Aloe arborescens) were rich enough to support growth of rhizobacteria. Representative isolates of Enterobacter spp., Klebsiella spp., Bacillus spp. and Azospirillum spp. exhibited good growth on agar plates of such plant-based culture media. Cell growth and biomass production in liquid batch cultures were comparable to those reported with the synthetic culture media. In addition, the tested plant-based culture media efficiently recovered populations of rhizobacteria associated to plant roots. Culturable populations of >10(6)-10(8) cfu g(-1) were recovered from the ecto- and endo-rhizospheres of tested host plants. More than 100 endophytic culture-dependent isolates were secured and subjected to morphophysiological identification. Factor and cluster analyses indicated the unique community structure, on species, genera, class and phyla levels, of the culturable population recovered with plant-based culture media, being distinct from that obtained with the chemically-synthetic culture media. Proteobacteria were the dominant (78.8%) on plant-based agar culture medium compared to only 31% on nutrient agar, while Firmicutes prevailed on nutrient agar (69%) compared to the plant-based agar culture media (18.2%). Bacteroidetes, represented by Chryseobacterium indologenes, was only reported (3%) among the culturable rhizobacteria community of the plant-based agar culture medium.

  15. Project in determination of crystal structure of nitrogen fixation proteins from azospirilum brasiliense and herbaspirilum seropedicae by synchrotron x-ray diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Barbosa, Valma M.; Leggs, Luciana A.; Delboni, Luis F.; Chubatsu, LedaS.; Souza, Emanuel M.; Machado, Hidevaldo B.; Yates, Geoffrey M.; Pedrosa, Fabio O. [Parana Univ., Curitiba, PR (Brazil). Dept. de Bioquimica

    1996-12-31

    Full text. Biological nitrogen fixation is essential for maintaining the nitrogen cycle on earth and of high importance for Brazilian agriculture. The nitrogenase enzyme system, which provides the biochemical machinery for nitrogen fixation, consists of two component metalloproteins, the molybdenumiron (Mo Fe) protein and the iron (Fe) protein. Nitrogen fixation is a very energy-intensive process, requiring around 16 moles of ATP for each mol of N{sub 2} fixed (reduced). As a consequence, synthesis and activity of nitrogenase is tighty regulated at two levels: general and specific. The general level regulation is mediated by the ntr (nitrogen regulation) system. Two gene products are involved: the ntrB gene product (NtrB) is responsible for the activation of the ntrC gene product (NtrC) by phosphorylating a conserved Asp54, which activates the expression of the nifA gene. The nif specific control system is mediated by the NifA protein, which binds to a DNA specific sequence (UAS, Upstream Activator Sequence) and activates nif promoter transcriptions by RNA polymerase-{sup {alpha}54}, following ATP hydrolysis. The aim of this project is to solve the crystal structure of dinitrogenase reductase (iron protein) and dinitrogenase (molybdenum-iron protein) from Azospirilim brasiliense and the regulatory proteins NifA from Herbaspirillum seropedicae and NtrC Azospirillum brasiliense. The three dimensional structure of the proteins involved in this project will allow a better understanding of the mechanism of biological nitrogen fixation. To this end, the data collection will probably be done at the LNLS facilities which will be available in the near future. (author)

  16. Shifts in taxonomic and functional microbial diversity with agriculture: How fragile is the Brazilian Cerrado?

    Science.gov (United States)

    Souza, Renata Carolini; Mendes, Iêda Carvalho; Reis-Junior, Fábio Bueno; Carvalho, Fabíola Marques; Nogueira, Marco Antonio; Vasconcelos, Ana Tereza Ribeiro; Vicente, Vânia Aparecida; Hungria, Mariangela

    2016-03-16

    The Cerrado--an edaphic type of savannah--comprises the second largest biome of the Brazilian territory and is the main area for grain production in the country, but information about the impact of land conversion to agriculture on microbial diversity is still scarce. We used a shotgun metagenomic approach to compare undisturbed (native) soil and soils cropped for 23 years with soybean/maize under conservation tillage--"no-till" (NT)--and conventional tillage (CT) systems in the Cerrado biome. Soil management and fertilizer inputs with the introduction of agriculture improved chemical properties, but decreased soil macroporosity and microbial biomass of carbon and nitrogen. Principal coordinates analyses confirmed different taxonomic and functional profiles for each treatment. There was predominance of the Bacteria domain, especially the phylum Proteobacteria, with higher numbers of sequences in the NT and CT treatments; Archaea and Viruses also had lower numbers of sequences in the undisturbed soil. Within the Alphaproteobacteria, there was dominance of Rhizobiales and of the genus Bradyrhizobium in the NT and CT systems, attributed to massive inoculation of soybean, and also of Burkholderiales. In contrast, Rhizobium, Azospirillum, Xanthomonas, Pseudomonas and Acidobacterium predominated in the native Cerrado. More Eukaryota, especially of the phylum Ascomycota were detected in the NT. The functional analysis revealed lower numbers of sequences in the five dominant categories for the CT system, whereas the undisturbed Cerrado presented higher abundance. High impact of agriculture in taxonomic and functional microbial diversity in the biome Cerrado was confirmed. Functional diversity was not necessarily associated with taxonomic diversity, as the less conservationist treatment (CT) presented increased taxonomic sequences and reduced functional profiles, indicating a strategy to try to maintain soil functioning by favoring taxa that are probably not the most

  17. Effect of inorganic nitrogenous fertilizer on productivity of recently reclaimed saline sodic soils with and without biofertilizer.

    Science.gov (United States)

    Mehdi, S M; Sarfraz, M; Shabbir, G; Abbas, G

    2007-07-15

    Saline sodic soils after reclamation become infertile due to leaching of most of the nutrients along with salts from the rooting medium. Microbes can play a vital role in the productivity improvement of such soils. In this study a saline sodic field having EC, 6.5 dS m(-1), pH, 9.1 and gypsum requirement (GR) 3.5 tons acre(-1) was reclaimed by applying gypsum at the rate of 100% GR. Rice and wheat crops were transplanted/sown for three consecutive years. Inorganic nitrogenous fertilizer was used with and without biofertilizers i.e., Biopower (Azospirillum) for rice and diazotroph inoculums for wheat. Nitrogen was applied at the rate of 0, 75% of recommended dose (RD), RD, 125% of RD and 150% of RD. Recommended dose of P without K was applied to all the plots. Biopower significantly improved Paddy and straw yield of rice over inorganic nitrogenous fertilizer. In case of wheat diazotroph inoculum improved grain and straw yield significantly over inorganic nitrogenous fertilizer. Among N fertilizer rates, RD + 25% additional N fertilizer was found to be the best dose for rice and wheat production in recently reclaimed soils. Nitrogen concentration and its uptake by paddy, grain and straw were also increased by biopower and diazotroph inoculum over inorganic nitrogenous fertilizer. Among N fertilizer rates, RD + 25% additional N fertilizer was found to be the best dose for nitrogen concentration and its uptake by paddy, grain and straw. Total soil N, available P and extractable K were increased while salinity/sodicity parameters were decreased with the passage of time. The productivity of the soil was improved more by biofertilizers over inorganic N fertilizers.

  18. Grain, milling, and head rice yields as affected by nitrogen rate and bio-fertilizer application

    Directory of Open Access Journals (Sweden)

    Saeed FIROUZI

    2015-11-01

    Full Text Available To evaluate the effects of nitrogen rate and bio-fertilizer application on grain, milling, and head rice yields, a field experiment was conducted at Rice Research Station of Tonekabon, Iran, in 2013. The experimental design was a factorial treatment arrangement in a randomized complete block with three replicates. Factors were three N rates (0, 75, and 150 kg ha-1 and two bio-fertilizer applications (inoculation and uninoculation with Nitroxin, a liquid bio-fertilizer containing Azospirillum spp. and Azotobacter spp. bacteria. Analysis of variance showed that rice grain yield, panicle number per m2, grain number per panicle, flag leaves area, biological yield, grains N concentration and uptake, grain protein concentration, and head rice yield were significantly affected by N rate, while bio-fertilizer application had significant effect on rice grain yield, grain number per panicle, flag leaves area, biological yield, harvest index, grains N concentration and uptake, and grain protein concentration. Results showed that regardless of bio-fertilizer application, rice grain and biological yields were significantly increased as N application rate increased from 0 to 75 kg ha-1, but did not significantly increase at the higher N rate (150 kg ha-1. Grain yield was significantly increased following bio-fertilizer application when averaged across N rates. Grains N concentration and uptake were significantly increased as N rate increased up to 75 kg ha-1, but further increases in N rate had no significant effect on these traits. Bio-fertilizer application increased significantly grains N concentration and uptake, when averaged across N rates. Regardless of bio-fertilizer application, head rice yield was significantly increased from 56 % to 60 % when N rate increased from 0 to 150 kg ha-1. Therefore, this experiment illustrated that rice grain and head yields increased with increasing N rate, while bio-fertilizer application increased only rice grain

  19. Recycling of Treated Sewage Sludge in Sustainable Agriculture

    International Nuclear Information System (INIS)

    Galal, Y.G.M.

    2012-01-01

    Agricultural utilization of organic wastes amendments has been shown to be a sound alternative for both waste recycling and soil fertility improvement. Also, attention had been paid to use the biological agents that most cheap and safe for agricultural application in poor sandy soils. In this respect, irradiated sewage sludge and individual and dual inoculants of Azospirillum, Rhizobium and Arbuscular mycorrhizae fungi were applied for reclamation and development of low fertile sandy soil. The fertilizer value of sewage sludge has been known for a long time, but the concomitant problems of heavy metals in soil, as a result of its continuous applications, have only been recognized recently. Most of the studies were devoted to follow up the effect of high concentrations of metals when sewage sludge was applied, but no attention has been accelerated about its effect on soil microorganisms. Adverse effects of sewage sludge on microbial activity and populations of cyanobacteria, Rhizobium, Mycorrhizae and total microbial biomass have been detected in some cases of Europe. For example, N 2 fixation by free-living heterotrophic bacteria was found to be inhibited at concentrations (mg kg -1 ) of 127 Zn, 37 Cu, 21 Ni, 3.4 Cd, 52 Cr, and 71 Pb. Impact of bio fertilizers combined with irradiated sewage sludge on micro nutrients, e.g. Fe, Zn, Mn, Pb availability to clover and wheat plants, and productivity of both crops was the main objective of this study. In this connection, nuclear technology may offer a safety method against pathogenic effects of sewage sludge applied into agricultural ecosystems. Therefore, irradiated sludge is considered as safely source of organic wastes as well as the benefits on enrichment the low fertile soil with available nutrients, which act as a limiting factor for crop production. The N, P and K nutrients uptake by either shoots or grains of tested crops were positively and significantly affected by application of sewage sludge as well as bio

  20. Temporal dynamics of abundance and composition of nitrogen-fixing communities across agricultural soils.

    Directory of Open Access Journals (Sweden)

    Michele C Pereira E Silva

    Full Text Available BACKGROUND: Despite the fact that the fixation of nitrogen is one of the most significant nutrient processes in the terrestrial ecosystem, a thorough study of the spatial and temporal patterns in the abundance and distribution of N-fixing communities has been missing so far. METHODOLOGY/PRINCIPAL FINDINGS: In order to understand the dynamics of diazotrophic communities and their resilience to external changes, we quantified the abundance and characterized the bacterial community structures based on the nifH gene, using real-time PCR, PCR-DGGE and 454-pyrosequencing, across four representative Dutch soils during one growing season. In general, higher nifH gene copy numbers were observed in soils with higher pH than in those with lower pH, but lower numbers were related to increased nitrate and ammonium levels. Results from nifH gene pyrosequencing confirmed the observed PCR-DGGE patterns, which indicated that the N fixers are highly dynamic across time, shifting around 60%. Forward selection on CCA analysis identified N availability as the main driver of these variations, as well as of the evenness of the communities, leading to very unequal communities. Moreover, deep sequencing of the nifH gene revealed that sandy soils (B and D had the lowest percentage of shared OTUs across time, compared with clayey soils (G and K, indicating the presence of a community under constant change. Cosmopolitan nifH species (present throughout the season were affiliated with Bradyrhizobium, Azospirillum and Methylocistis, whereas other species increased their abundances progressively over time, when appropriate conditions were met, as was notably the case for Paenibacilus and Burkholderia. CONCLUSIONS: Our study provides the first in-depth pyrosequencing analysis of the N-fixing community at both spatial and temporal scales, providing insights into the cosmopolitan and specific portions of the nitrogen fixing bacterial communities in soil.

  1. Evaluation the effects of organic, biological and chemical fertilizers on morphological traits, yield and yield components of Basil (Ocimum basilicum L.

    Directory of Open Access Journals (Sweden)

    S. M.K Tahhami Zarandi

    2015-04-01

    Full Text Available The use of organic manure and biofertilizers containing beneficial microorganisms instead of chemical fertilizers are known to improve plant growth through supply of plant nutrients and can help sustain environmental health and soil productivity. Because of special pr