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Sample records for rhizobium etli final

  1. Isolation and characterization of Rhizobium etli mutants altered in degradation of asparagine.

    Huerta-Zepeda, A; Ortuño, L; Du Pont, G; Durán, S; Lloret, A.; MERCHANT-LARIOS, H.; Calderón, J.

    1997-01-01

    Rhizobium etli mutants unable to grow on asparagine as the nitrogen and carbon source were isolated. Two kinds of mutants were obtained: AHZ1, with very low levels of aspartase activity, and AHZ7, with low levels of asparaginase and very low levels of aspartase compared to the wild-type strain. R. etli had two asparaginases differentiated by their thermostabilities, electrophoretic mobilities, and modes of regulation. The AHZ mutants nodulated as did the wild-type strain and had nitrogenase l...

  2. Mechanisms of Inhibition of Rhizobium etli Pyruvate Carboxylase by l-Aspartate

    Sirithanakorn, Chaiyos; Adina-Zada, Abdussalam; Wallace, John C.; Jitrapakdee, Sarawut; Attwood, Paul V.

    2014-01-01

    l-Aspartate is a regulatory feedback inhibitor of the biotin-dependent enzyme pyruvate carboxylase in response to increased levels of tricarboxylic acid cycle intermediates. Detailed studies of l-aspartate inhibition of pyruvate carboxylase have been mainly confined to eukaryotic microbial enzymes, and aspects of its mode of action remain unclear. Here we examine its inhibition of the bacterial enzyme Rhizobium etli pyruvate carboxylase. Kinetic studies demonstrated that l-aspartate binds to ...

  3. Symbiosis-specific expression of Rhizobium etli casA encoding a secreted calmodulin-related protein

    Xi, Chuanwu; Schoeters, Eric; Vanderleyden, Jozef; Michiels, Jan

    2000-01-01

    Symbiosis between Rhizobium and its leguminous host requires elaborate communication between the partners throughout the interaction process. A calmodulin-like protein, termed calsymin, was identified in Rhizobium etli; a calmodulin-related protein in a Gram-negative bacterium had not been described previously. Calsymin possesses three repeated homologous domains. Each domain contains two predicted EF-hand Ca2+-binding motifs. Ca2+-binding activity of calsymin ...

  4. Genome Sequence of Rhizobium etli CNPAF512, a Nitrogen-Fixing Symbiont Isolated from Bean Root Nodules in Brazil ?

    Fauvart, Maarten; Sánchez-Rodríguez, Aminael; Beullens, Serge; Marchal, Kathleen; Michiels, Jan

    2011-01-01

    Rhizobium etli is a Gram-negative soil-dwelling alphaproteobacterium that carries out symbiotic biological nitrogen fixation in close association with legume hosts. R. etli strains exhibit high sequence divergence and are geographically structured, with a potentially dramatic influence on the outcome of symbiosis. Here, we present the genome sequence of R. etli CNPAF512, a Brazilian isolate from bean nodules. We anticipate that the availability of genome sequences of R. etli strains from dist...

  5. Genomic lineages of Rhizobium etli revealed by the extent of nucleotide polymorphisms and low recombination

    González Víctor

    2011-10-01

    Full Text Available Abstract Background Most of the DNA variations found in bacterial species are in the form of single nucleotide polymorphisms (SNPs, but there is some debate regarding how much of this variation comes from mutation versus recombination. The nitrogen-fixing symbiotic bacteria Rhizobium etli is highly variable in both genomic structure and gene content. However, no previous report has provided a detailed genomic analysis of this variation at nucleotide level or the role of recombination in generating diversity in this bacterium. Here, we compared draft genomic sequences versus complete genomic sequences to obtain reliable measures of genetic diversity and then estimated the role of recombination in the generation of genomic diversity among Rhizobium etli. Results We identified high levels of DNA polymorphism in R. etli, and found that there was an average divergence of 4% to 6% among the tested strain pairs. DNA recombination events were estimated to affect 3% to 10% of the genomic sample analyzed. In most instances, the nucleotide diversity (π was greater in DNA segments with recombinant events than in non-recombinant segments. However, this degree of recombination was not sufficiently large to disrupt the congruence of the phylogenetic trees, and further evaluation of recombination in strains quartets indicated that the recombination levels in this species are proportionally low. Conclusion Our data suggest that R. etli is a species composed of separated lineages with low homologous recombination among the strains. Horizontal gene transfer, particularly via the symbiotic plasmid characteristic of this species, seems to play an important role in diversity but the lineages maintain their evolutionary cohesiveness.

  6. Role of trehalose in heat and desiccation tolerance in the soil bacterium Rhizobium etli

    Reina-Bueno Mercedes

    2012-09-01

    Full Text Available Abstract Background The compatible solute trehalose is involved in the osmostress response of Rhizobium etli, the microsymbiont of Phaseolus vulgaris. In this work, we reconstructed trehalose metabolism in R. etli, and investigated its role in cellular adaptation and survival to heat and desiccation stress under free living conditions. Results Besides trehalose as major compatible solute, R. etli CE3 also accumulated glutamate and, if present in the medium, mannitol. Putative genes for trehalose synthesis (otsAB/treS/treZY, uptake (aglEFGK/thuEFGK and degradation (thuAB/treC were scattered among the chromosome and plasmids p42a, p42c, p42e, and p42f, and in some instances found redundant. Two copies of the otsA gene, encoding trehalose-6-P-synthase, were located in the chromosome (otsAch and plasmid p42a (otsAa, and the latter seemed to be acquired by horizontal transfer. High temperature alone did not influence growth of R. etli, but a combination of high temperature and osmotic stress was more deleterious for growth than osmotic stress alone. Although high temperature induced some trehalose synthesis by R. etli, trehalose biosynthesis was mainly triggered by osmotic stress. However, an otsAch mutant, unable to synthesize trehalose in minimal medium, showed impaired growth at high temperature, suggesting that trehalose plays a role in thermoprotection of R. etli. Desiccation tolerance by R. etli wild type cells was dependent of high trehalose production by osmotic pre-conditioned cells. Cells of the mutant strain otsAch showed ca. 3-fold lower survival levels than the wild type strain after drying, and a null viability after 4 days storage. Conclusions Our findings suggest a beneficial effect of osmotic stress in R. etli tolerance to desiccation, and an important role of trehalose on the response of R. etli to high temperature and desiccation stress.

  7. A Functional Bacterium-to-Plant DNA Transfer Machinery of Rhizobium etli.

    Lacroix, Benoît; Citovsky, Vitaly

    2016-03-01

    Different strains and species of the soil phytopathogen Agrobacterium possess the ability to transfer and integrate a segment of DNA (T-DNA) into the genome of their eukaryotic hosts, which is mainly mediated by a set of virulence (vir) genes located on the bacterial Ti-plasmid that also contains the T-DNA. To date, Agrobacterium is considered to be unique in its capacity to mediate genetic transformation of eukaryotes. However, close homologs of the vir genes are encoded by the p42a plasmid of Rhizobium etli; this microorganism is related to Agrobacterium, but known only as a symbiotic bacterium that forms nitrogen-fixing nodules in several species of beans. Here, we show that R. etli can mediate functional DNA transfer and stable genetic transformation of plant cells, when provided with a plasmid containing a T-DNA segment. Thus, R. etli represents another bacterial species, besides Agrobacterium, that encodes a protein machinery for DNA transfer to eukaryotic cells and their subsequent genetic modification. PMID:26968003

  8. The extracellular proteome of Rhizobium etli CE3 in exponential and stationary growth phase

    Mendoza-Hernández Guillermo

    2010-10-01

    Full Text Available Abstract Background The extracellular proteome or secretome of symbiotic bacteria like Rhizobium etli is presumed to be a key element of their infection strategy and survival. Rhizobia infect the roots of leguminous plants and establish a mutually beneficial symbiosis. To find out the possible role of secreted proteins we analyzed the extracellular proteome of R. etli CE3 in the exponential and stationary growth phases in minimal medium, supplemented with succinate-ammonium. Results The extracellular proteins were obtained by phenol extraction and identified by LC-ESI MS/MS. We identified 192 and 191 proteins for the exponential and stationary phases respectively. Using the software Signal P, we predicted signal peptides for 12.95% and 35.60% of the proteins identified in the exponential and stationary phases, respectively, which could therefore be secreted by the Sec pathway. For the exponential growth phase, we found in abundance proteins like the ribosomal proteins, toxins and proteins belonging to the group "defence mechanisms". For the stationary growth phase, we found that the most abundant proteins were those with unknown function, and in many of these we identified characteristic domains of proteases and peptidases. Conclusions Our study provided the first dataset of the secretome of R. etli and its modifications, which may lead to novel insights into the adaptive response of different stages of growth. In addition, we found a high number of proteins with unknown function; these proteins could be analyzed in future research to elucidate their role in the extracellular proteome of R. etli.

  9. Rhizobium etli asparaginase II: an alternative for acute lymphoblastic leukemia (ALL) treatment.

    Huerta-Saquero, Alejandro; Evangelista-Martínez, Zahaed; Moreno-Enriquez, Angélica; Perez-Rueda, Ernesto

    2013-01-01

    Bacterial L-asparaginase has been a universal component of therapies for childhood acute lymphoblastic leukemia since the 1970s. Two principal enzymes derived from Escherichia coli and Erwinia chrysanthemi are the only options clinically approved to date. We recently reported a study of recombinant L-asparaginase (AnsA) from Rhizobium etli and described an increasing type of AnsA family members. Sequence analysis revealed four conserved motifs with notable differences with respect to the conserved regions of amino acid sequences of type I and type II L-asparaginases, particularly in comparison with therapeutic enzymes from E. coli and E. chrysanthemi. These differences suggested a distinct immunological specificity. Here, we report an in silico analysis that revealed immunogenic determinants of AnsA. Also, we used an extensive approach to compare the crystal structures of E. coli and E. chrysantemi asparaginases with a computational model of AnsA and identified immunogenic epitopes. A three-dimensional model of AsnA revealed, as expected based on sequence dissimilarities, completely different folding and different immunogenic epitopes. This approach could be very useful in transcending the problem of immunogenicity in two major ways: by chemical modifications of epitopes to reduce drug immunogenicity, and by site-directed mutagenesis of amino acid residues to diminish immunogenicity without reduction of enzymatic activity. PMID:22895060

  10. Rhizobium etli USDA9032 Engineered To Produce a Phenazine Antibiotic Inhibits the Growth of Fungal Pathogens but Is Impaired in Symbiotic Performance▿

    Krishnan, Hari B.; Kang, Beom Ryong; Hari Krishnan, Ammulu; Kim, Kil Yong; Kim, Young Cheol

    2006-01-01

    Phenazine production was engineered in Rhizobium etli USDA9032 by the introduction of the phz locus of Pseudomonas chlororaphis O6. Phenazine-producing R. etli was able to inhibit the growth of Botrytis cinerea and Fusarium oxysporum in vitro. Black bean inoculated with phenazine-producing R. etli produced brownish Fix− nodules.

  11. Pleiotropic effects of a rel mutation on stress survival of Rhizobium etli CNPAF512

    Beullens Serge

    2008-12-01

    Full Text Available Abstract Background The rel gene of Rhizobium etli (relRet, the nodulating endosymbiont of the common bean plant, determines the cellular level of the alarmone (pppGpp and was previously shown to affect free-living growth and symbiosis. Here, we demonstrate its role in cellular adaptation and survival in response to various stresses. Results Growth of the R. etli relRet mutant was strongly reduced or abolished in the presence of elevated NaCl levels or at 37°C, compared to the wild type. In addition, depending on the cell density, decreased survival of exponentially growing or stationary phase relRet mutant cells was obtained after H2O2, heat or NaCl shock compared to the wild-type strain. Survival of unstressed stationary phase cultures was differentially affected depending on the growth medium used. Colony forming units (CFU of relRet mutant cultures continuously decreased in minimal medium supplemented with succinate, whereas wild-type cultures stabilised at higher CFU levels. Microscopic examination of stationary phase cells indicated that the relRet mutant was unable to reach the typical coccoid morphology of the wild type in stationary phase cultures. Assessment of stress resistance of re-isolated bacteroids showed increased sensitivity of the relRet mutant to H2O2 and a slightly increased resistance to elevated temperature (45°C or NaCl shock, compared to wild-type bacteroids. Conclusion The relRet gene is an important factor in regulating rhizobial physiology, during free-living growth as well as in symbiotic conditions. Additionally, differential responses to several stresses applied to bacteroids and free-living exponential or stationary phase cells point to essential physiological differences between the different states.

  12. Genetic Basis for Rhizobium etli CE3 O-Antigen O-Methylated Residues That Vary According to Growth Conditions▿

    Ojeda, Kristylea J.; Box, Jodie M.; Noel, K. Dale

    2009-01-01

    The Rhizobium etli CE3 O antigen is a fixed-length heteropolymer with O methylation being the predominant type of sugar modification. There are two O-methylated residues that occur, on average, once per complete O antigen: a multiply O-methylated terminal fucose and 2-O methylation of a fucose residue within a repeating unit. The amount of the methylated terminal fucose decreases and the amount of 2-O-methylfucose increases when bacteria are grown in the presence of the host plant, Phaseolus ...

  13. Host genes involved in nodulation preference in common bean (Phaseolus vulgaris)-rhizobium etli symbiosis revealed by suppressive subtractive hybridization.

    Meschini, Eitel Peltzer; Blanco, Flavio Antonio; Zanetti, María Eugenia; Beker, María Pía; Küster, Helge; Pühler, Alfred; Aguilar, O Mario

    2008-04-01

    Common bean cultivars are nodulated preferentially by Rhizobium etli lineages from the same center of host diversification. Nodulation was found to be earlier and numerous in bean plants inoculated with the cognate strain. We predicted that analysis of transcripts at early stages of the interaction between host and rhizobium would identify plant genes that are most likely to be involved in this preferential nodulation. Therefore, we applied a suppressive subtractive hybridization approach in which cDNA from a Mesoamerican cultivar inoculated with either the more- or less-efficient strain of R. etli was used as the driver and the tester, respectively. Forty-one independent tentative consensus sequences (TCs) were obtained and classified into different functional categories. Of 11 selected TCs, 9 were confirmed by quantitative reverse-transcriptase polymerase chain reaction. Two genes show high homology to previously characterized plant receptors. Two other upregulated genes encode for Rab11, a member of the small GTP-binding protein family, and HAP5, a subunit of the heterotrimeric CCAAT-transcription factor. Interestingly, one of the TCs encodes for an isoflavone reductase, which may lead to earlier Nod factor production by specific strains of rhizobia. The transcript abundance of selected cDNAs also was found to be higher in mature nodules of the more efficient interaction. Small or no differences were observed when an Andean bean cultivar was inoculated with a cognate strain, suggesting involvement of these genes in the strain-specific response. The potential role of these genes in the early preferential symbiotic interaction is discussed. PMID:18321191

  14. Altered Lipid A Structures and Polymyxin Hypersensitivity of Rhizobium etli Mutants Lacking the LpxE and LpxF Phosphatases

    Ingram, Brian O.; Sohlenkamp, Christian; Geiger, Otto; Raetz, Christian R. H.

    2010-01-01

    The lipid A of Rhizobium etli, a nitrogen-fixing plant endosymbiont, displays significant structural differences when compared to that of Escherichia coli. An especially striking feature of R. etli lipid A is that it lacks both the 1- and 4?phosphate groups. The 4?-phosphate moiety of the distal glucosamine unit is replaced with a galacturonic acid residue. The dephosphorylated proximal unit is present as a mixture of the glucosamine hemiacetal and an oxidized 2-aminogluconate derivative. Dis...

  15. Enhanced Nitrogen Fixation in a Rhizobium etli ntrC Mutant That Overproduces the Bradyrhizobium japonicum Symbiotic Terminal Oxidase cbb3

    Soberón, Mario; López, Oswaldo; Morera, Claudia; Girard, Maria de Lourdes; Tabche, Maria Luisa; Miranda, Juan

    1999-01-01

    The ntrC gene codes for a transcriptional activator protein that modulates gene expression in response to nitrogen. The cytochrome production pattern of a Rhizobium etli ntrC mutant (CFN2012) was studied. CO difference spectral analysis of membranes showed that CFN2012 produced a terminal oxidase similar to the symbiotic terminal oxidase of bacteroids in free-living cells under aerobic conditions, with a characteristic trough at 553 nm. CFN2012 produced two c-type cytochromes with molecular m...

  16. A type III polyketide synthase from Rhizobium etli condenses malonyl CoAs to a heptaketide pyrone with unusually high catalytic efficiency.

    Jeya, Marimuthu; Kim, Tae-Su; Kumar Tiwari, Manish; Li, Jinglin; Zhao, Huimin; Lee, Jung-Kul

    2012-10-30

    A novel type III polyketide synthase (RePKS) from Rhizobium etli produced a heptaketide pyrone using acetyl-CoA and six molecules of malonyl-CoA. Its catalytic efficiency (k(cat)/K(m) = 5230 mM(-1) min(-1)) for malonyl CoA was found to be the highest ever reported. Molecular dynamics studies revealed the unique features of RePKS. PMID:23059854

  17. Changes in the Common Bean Transcriptome in Response to Secreted and Surface Signal Molecules of Rhizobium etli.

    Dalla Via, Virginia; Narduzzi, Candela; Aguilar, Orlando Mario; Zanetti, María Eugenia; Blanco, Flavio Antonio

    2015-10-01

    Establishment of nitrogen-fixing symbiosis requires the recognition of rhizobial molecules to initiate the development of nodules. Using transcriptional profiling of roots inoculated with mutant strains defective in the synthesis of Nod Factor (NF), exopolysaccharide (EPS), or lipopolysaccharide (LPS), we identified 2,606 genes from common bean (Phaseolus vulgaris) that are differentially regulated at early stages of its interaction with Rhizobium etli. Many transcription factors from different families are modulated by NF, EPS, and LPS in different combinations, suggesting that the plant response depends on the integration of multiple signals. Some receptors identified as differentially expressed constitute excellent candidates to participate in signal perception of molecules derived from the bacteria. Several components of the ethylene signal response, a hormone that plays a negative role during early stages of the process, were down-regulated by NF and LPS. In addition, genes encoding proteins involved in small RNA-mediated gene regulation were regulated by these signal molecules, such as Argonaute7, a specific component of the trans-acting short interfering RNA3 pathway, an RNA-dependent RNA polymerase, and an XH/XP domain-containing protein, which is part of the RNA-directed DNA methylation. Interestingly, a number of genes encoding components of the circadian central oscillator were down-regulated by NF and LPS, suggesting that a root circadian clock is adjusted at early stages of symbiosis. Our results reveal a complex interaction of the responses triggered by NF, LPS, and EPS that integrates information of the signals present in the surface or secreted by rhizobia. PMID:26282238

  18. Conservation of Plasmid-Encoded Traits among Bean-Nodulating Rhizobium Species

    Brom, Susana; Girard, Lourdes; García-de los Santos, Alejandro; Sanjuan-Pinilla, Julio M.; Olivares, José; Sanjuan, Juan

    2002-01-01

    Rhizobium etli type strain CFN42 contains six plasmids. We analyzed the distribution of genetic markers from some of these plasmids in bean-nodulating strains belonging to different species (Rhizobium etli, Rhizobium gallicum, Rhizobium giardinii, Rhizobium leguminosarum, and Sinorhizobium fredii). Our results indicate that independent of geographic origin, R. etli strains usually share not only the pSym plasmid but also other plasmids containing symbiosis-related genes, with a similar organi...

  19. Altered lipid A structures and polymyxin hypersensitivity of Rhizobium etli mutants lacking the LpxE and LpxF phosphatases.

    Ingram, Brian O; Sohlenkamp, Christian; Geiger, Otto; Raetz, Christian R H

    2010-05-01

    The lipid A of Rhizobium etli, a nitrogen-fixing plant endosymbiont, displays significant structural differences when compared to that of Escherichia coli. An especially striking feature of R. etli lipid A is that it lacks both the 1- and 4'-phosphate groups. The 4'-phosphate moiety of the distal glucosamine unit is replaced with a galacturonic acid residue. The dephosphorylated proximal unit is present as a mixture of the glucosamine hemiacetal and an oxidized 2-aminogluconate derivative. Distinct lipid A phosphatases directed to the 1 or the 4'-positions have been identified previously in extracts of R. etli and Rhizobium leguminosarum. The corresponding structural genes, lpxE and lpxF, respectively, have also been identified. Here, we describe the isolation and characterization of R. etli deletion mutants in each of these phosphatase genes and the construction of a double phosphatase mutant. Mass spectrometry confirmed that the mutant strains completely lacked the wild-type lipid A species and accumulated the expected phosphate-containing derivatives. Moreover, radiochemical analysis revealed that phosphatase activity was absent in membranes prepared from the mutants. Our results indicate that LpxE and LpxF are solely responsible for selectively dephosphorylating the lipid A molecules of R. etli. All the mutant strains showed an increased sensitivity to polymyxin relative to the wild-type. However, despite the presence of altered lipid A species containing one or both phosphate groups, all the phosphatase mutants formed nitrogen-fixing nodules on Phaseolus vulgaris. Therefore, the dephosphorylation of lipid A molecules in R. etli is not required for nodulation but may instead play a role in protecting the bacteria from cationic antimicrobial peptides or other immune responses of plants. PMID:20153447

  20. Characterization of the NifA-RpoN regulon in Rhizobium etli in free life and in symbiosis with Phaseolus vulgaris.

    Salazar, Emmanuel; Díaz-Mejía, J Javier; Moreno-Hagelsieb, Gabriel; Martínez-Batallar, Gabriel; Mora, Yolanda; Mora, Jaime; Encarnación, Sergio

    2010-07-01

    The NifA-RpoN complex is a master regulator of the nitrogen fixation genes in alphaproteobacteria. Based on the complete Rhizobium etli genome sequence, we constructed an R. etli CFN42 oligonucleotide (70-mer) microarray and utilized this tool, reverse transcription (RT)-PCR analysis (transcriptomics), proteomics, and bioinformatics to decipher the NifA-RpoN regulon under microaerobic conditions (free life) and in symbiosis with bean plants. The R. etli NifA-RpoN regulon was determined to contain 78 genes, including the genes involved in nitrogen fixation, and the analyses revealed 42 new NifA-RpoN-dependent genes. More importantly, this study demonstrated that the NifA-RpoN regulon is composed of genes and proteins that have very diverse functions, that play fundamental and previously less appreciated roles in regulating the normal physiology of the cell, and that have important functions in providing adequate conditions for efficient nitrogen fixation in symbiosis. The R. etli NifA-RpoN regulon defined here has some components in common with other NifA-RpoN regulons described previously, but the vast majority of the components have been found only in the R. etli regulon, suggesting that they have a specific role in this bacterium and particular requirements during nitrogen fixation compared with other symbiotic bacterial models. PMID:20453139

  1. Effets de la double symbiose Rhizobium TAL 1147-Glomus clarum sur la croissance et la nodulation de Racosperma auriculiforme en République Démocratique du Congo

    Bulakali, B.

    1999-01-01

    Full Text Available Effects of Inoculation with Rhizobium TAL 1147'-Glomus Clarum in a Nursery on Racosperma Auriculiforme Growth and Nodulation in Democratie Republic of Congo. The efficiency evaluation of five vesicular-arbuscular mycorrhiza spp. revealed that the mycobiont Glomus clarum is suitable for the mycorrhizogene replanting of the Kinzono grassy savanna. This present study reports results of effects of its inoculation at the same time that the Rhizobium TAL 1147 in nursery on Racosperma auriculiforme growth and nodulation in this same savanna's soil. Compared to the individual inoculation (Glomus clarum or Rhizobium TAL 1147 and to the uninoculated control, the dual inoculation Rhizobium TAL 1147-Glomus clarum has improved significantly (P <0.01 the growth and the nodulation of this legume tree five months after the sowing. A such inoculation can be recommended for an effective implantation at large-scale of this specie in poor Kinzono soil in nitrogen and in soluble phosphore.

  2. Effets de la double symbiose Rhizobium TAL 1147-Glomus clarum sur la croissance et la nodulation de Racosperma auriculiforme en République Démocratique du Congo

    Bulakali, B.; Lumande, K.; Mbaya, N.; Luyindula, N.; Mwange, K

    1999-01-01

    Effects of Inoculation with Rhizobium TAL 1147'-Glomus Clarum in a Nursery on Racosperma Auriculiforme Growth and Nodulation in Democratie Republic of Congo. The efficiency evaluation of five vesicular-arbuscular mycorrhiza spp. revealed that the mycobiont Glomus clarum is suitable for the mycorrhizogene replanting of the Kinzono grassy savanna. This present study reports results of effects of its inoculation at the same time that the Rhizobium TAL 1147 in nursery on Racosperma auriculiforme ...

  3. The micro-RNA72c-APETALA2-1 node as a key regulator of the common bean-Rhizobium etli nitrogen fixation symbiosis.

    Nova-Franco, Bárbara; Íñiguez, Luis P; Valdés-López, Oswaldo; Alvarado-Affantranger, Xochitl; Leija, Alfonso; Fuentes, Sara I; Ramírez, Mario; Paul, Sujay; Reyes, José L; Girard, Lourdes; Hernández, Georgina

    2015-05-01

    Micro-RNAs are recognized as important posttranscriptional regulators in plants. The relevance of micro-RNAs as regulators of the legume-rhizobia nitrogen-fixing symbiosis is emerging. The objective of this work was to functionally characterize the role of micro-RNA172 (miR172) and its conserved target APETALA2 (AP2) transcription factor in the common bean (Phaseolus vulgaris)-Rhizobium etli symbiosis. Our expression analysis revealed that mature miR172c increased upon rhizobial infection and continued increasing during nodule development, reaching its maximum in mature nodules and decaying in senescent nodules. The expression of AP2-1 target showed a negative correlation with miR172c expression. A drastic decrease in miR172c and high AP2-1 mRNA levels were observed in ineffective nodules. Phenotypic analysis of composite bean plants with transgenic roots overexpressing miR172c or a mutated AP2-1 insensitive to miR172c cleavage demonstrated the pivotal regulatory role of the miR172 node in the common bean-rhizobia symbiosis. Increased miR172 resulted in improved root growth, increased rhizobial infection, increased expression of early nodulation and autoregulation of nodulation genes, and improved nodulation and nitrogen fixation. In addition, these plants showed decreased sensitivity to nitrate inhibition of nodulation. Through transcriptome analysis, we identified 114 common bean genes that coexpressed with AP2-1 and proposed these as being targets for transcriptional activation by AP2-1. Several of these genes are related to nodule senescence, and we propose that they have to be silenced, through miR172c-induced AP2-1 cleavage, in active mature nodules. Our work sets the basis for exploring the miR172-mediated improvement of symbiotic nitrogen fixation in common bean, the most important grain legume for human consumption. PMID:25739700

  4. Transcriptional and functional variation of NF-YC1 in genetically diverse accessions of Phaseolus vulgaris during the symbiotic association with Rhizobium etli.

    Mazziotta, L; Reynoso, M A; Aguilar, O M; Blanco, F A; Zanetti, M E

    2013-09-01

    Phaseolus vulgaris (common bean) is an agronomic important legume crop native to America, where two centres of genetic diversification (GD) are recognised, one in Mesoamerica and the other in the south Andes. Mesoamerican bean accessions have preferential and more efficient nodulation with Rhizobium etli strains carrying the allele nodC type-α, which is predominant in soils of Mesoamerica. It was previously demonstrated that the host nuclear factor NF-YC1, which is involved in nodule formation and rhizobial infection, contributes to this preferential selection and enhances nodulation in the domesticated accession NAG12 from Mesoamerica. Here, we show that both domesticated and wild Mesoamerican beans exhibit higher nodulation performance with a nodC type-α than with a nodC type-δ strain. Transcripts of NF-YC1 significantly increased in roots of these accessions 24 h post-inoculation (hpi) with the nodC type-α strain. On the other hand, accessions from the Andean GD centre formed a higher number of nodules with a strain carrying the nodC type-δ, which is predominant in Andean soils. However, NF-YC1 transcript levels did not exhibit significant changes in Andean accessions upon inoculation with the nodC type-δ strain, at least at 24 hpi. RNA interference (RNAi)-mediated gene silencing of NF-YC1 in the domesticated Andean accession Alubia showed that NF-YC1 or a closely related member of this family is required for nodule formation and bacterial infection, in agreement with observations in Mesoamerican common beans. Isolation and sequencing of the full-length ORF of NF-YC1 from Alubia revealed that it was identical to the sequence previously identified in the Mesoamerican accession NAG12. Interestingly, overexpression of NF-YC1 had a negative impact on nodule formation in the Alubia accession, independently of the R. etli lineage. Our findings suggest that transcriptional and functional variation of NF-YC1 occurs among genetically diverse bean accessions, which might positively or negatively contribute to the fine-tuning mechanisms that regulate nodule formation in the common bean-R. etli symbiosis. PMID:23126265

  5. Caracterización fisiológica y molecular de la interacción Phaseolus (vulgaris: Rhizobium etli)

    Beker, María Pía

    2010-01-01

    En este trabajo de tesis se utilizó el sistema P. vulgaris-R. etli como modelo para investigar la afinidad entre porotos pertenecientes a los centros de diversificación de Mesoamérica y de la región Andina sureña y los rizobios de esas regiones. Teniendo en cuenta los eventos que se desarrollan desde el inicio del diálogo molecular hasta la formación del nódulo fijador de nitrógeno, el presente trabajo de tesis pretende contribuir al conocimiento de la interacción entre genotipos de poroto...

  6. A C subunit of the plant nuclear factor NF-Y required for rhizobial infection and nodule development affects partner selection in the common bean-Rhizobium etli symbiosis.

    Zanetti, María Eugenia; Blanco, Flavio A; Beker, María Pía; Battaglia, Marina; Aguilar, O Mario

    2010-12-01

    Legume plants are able to interact symbiotically with soil bacteria to form nitrogen-fixing root nodules. Although specific recognition between rhizobia and legume species has been extensively characterized, plant molecular determinants that govern the preferential colonization by different strains within a single rhizobium species have received little attention. We found that the C subunit of the heterotrimeric nuclear factor NF-Y from common bean (Phaseolus vulgaris) NF-YC1 plays a key role in the improved nodulation seen by more efficient strains of rhizobia. Reduction of NF-YC1 transcript levels by RNA interference (RNAi) in Agrobacterium rhizogenes-induced hairy roots leads to the arrest of nodule development and defects in the infection process with either high or low efficiency strains. Induction of three G2/M transition cell cycle genes in response to rhizobia was impaired or attenuated in NF-YC1 RNAi roots, suggesting that this transcription factor might promote nodule development by activating cortical cell divisions. Furthermore, overexpression of this gene has a positive impact on nodulation efficiency and selection of Rhizobium etli strains that are naturally less efficient and bad competitors. Our findings suggest that this transcription factor might be part of a mechanism that links nodule organogenesis with an early molecular dialogue that selectively discriminates between high- and low-quality symbiotic partners, which holds important implications for optimizing legume performance. PMID:21139064

  7. A C Subunit of the Plant Nuclear Factor NF-Y Required for Rhizobial Infection and Nodule Development Affects Partner Selection in the Common Bean–Rhizobium etli Symbiosis[C][W

    Zanetti, María Eugenia; Blanco, Flavio A.; Beker, María Pía; Battaglia, Marina; Aguilar, O. Mario

    2010-01-01

    Legume plants are able to interact symbiotically with soil bacteria to form nitrogen-fixing root nodules. Although specific recognition between rhizobia and legume species has been extensively characterized, plant molecular determinants that govern the preferential colonization by different strains within a single rhizobium species have received little attention. We found that the C subunit of the heterotrimeric nuclear factor NF-Y from common bean (Phaseolus vulgaris) NF-YC1 plays a key role in the improved nodulation seen by more efficient strains of rhizobia. Reduction of NF-YC1 transcript levels by RNA interference (RNAi) in Agrobacterium rhizogenes–induced hairy roots leads to the arrest of nodule development and defects in the infection process with either high or low efficiency strains. Induction of three G2/M transition cell cycle genes in response to rhizobia was impaired or attenuated in NF-YC1 RNAi roots, suggesting that this transcription factor might promote nodule development by activating cortical cell divisions. Furthermore, overexpression of this gene has a positive impact on nodulation efficiency and selection of Rhizobium etli strains that are naturally less efficient and bad competitors. Our findings suggest that this transcription factor might be part of a mechanism that links nodule organogenesis with an early molecular dialogue that selectively discriminates between high- and low-quality symbiotic partners, which holds important implications for optimizing legume performance. PMID:21139064

  8. Regulation of tryptophan genes in Rhizobium leguminosarum.

    Holmgren, E; I. P. Crawford

    1982-01-01

    Twelve tryptophan auxotrophs of Rhizobium leguminosarum were characterized biochemically. They were grown in complex and minimal media with several carbon sources, in both limiting and excess tryptophan. Missing enzyme activities allowed assignment of all mutant to the trpE, trpD, trpB, or trpA gene, confirming earlier results with the same mutants (Johnston et al., Mol. Gen. Genet. 165:323-330, 1978). In regulatory experiments, only the first enzyme of the pathway, anthranilate synthase, res...

  9. Effets de la fertilisation azotée, de l'inoculation par Rhizobium sp. et du régime des pluies sur la production de la biomasse et la teneur en azote du pois chiche

    Lachaâl M.

    2009-01-01

    Full Text Available Effect of nitrogen fertilization, inoculation with Rhizobium sp. and precipitation on the biomass production and nitrogen content of chickpea. Water availability and soil fertility (especially soil N content are the major factors affecting chickpea yield in Mediterranean regions, characterized by low rainfall, poorly distributed and rapid mineralization of organic matter. In order to study the effect of N-fertilization and inoculation with Rhizobium on chickpea biomass production and N-content, field experiment were carried out at two stations of INRAT in northern Tunisia during two consecutive years, 2000-2001 and 2001-2002. Results showed that N-fertilization significantly increased shoot biomass and N-content while decreasing nodule mass. Inoculation with both the two Rhizobium strains resulted in nodule mass increase but the shoot N-content was not significantly affected. Regardless of the stations and treatments, rainfall decrease between the two years of the experiment significantly reduced shoot and root biomass while improving nodulation, especially at Oued Beja. However, the nodule developed under water deficit conditions was correlated with a very high decrease of the nitrogen fixed. Nevertheless, the mineral nitrogen apply in soil improved the N-content of aerial parts in the two stations, especially in waterless season.

  10. Effets de la double symbiose Rhizobium-Glomus spp. sur la croissance de Leucaena leucocephala (Lam.) de Wit en pépinière, et dix mois après transplantation au Zaïre

    Bulakali, B.; Khasa, PD; Luyïndula, N.

    1992-01-01

    Effects of dual inoculation with Rhizobium and Glomus spp. on the growth of Leucaena leucocephala (Lam.) de Wit in the nursery, and ten months after outplanting in Zaire. This work underlines the utility to inoculate in the nursery Leucaena leucocephala (Lam.) de Wit, with efficient strains of Rhizobium and endomycorrhizal fungi, in order to ensure good initial plant growth after outplanting. In general, soil fumigation in the nursery allowed growth enhancement of control plants and the best ...

  11. Quinol oxidase encoded by cyoABCD in Rhizobium etli CFN42 is regulated by ActSR and is crucial for growth at low pH or low iron conditions.

    Lunak, Zachary R; Dale Noel, K

    2015-09-01

    Rhizobium etli aerobically respires with several terminal oxidases. The quinol oxidase (Cyo) encoded by cyoABCD is needed for efficient adaptation to low oxygen conditions and cyo transcription is upregulated at low oxygen. This study sought to determine how transcription of the cyo operon is regulated. The 5' sequence upstream of cyo was analysed in silico and revealed putative binding sites for ActR of the ActSR two-component regulatory system. The expression of cyo was decreased in an actSR mutant regardless of the oxygen condition. As ActSR is known to be important for growth under low pH in another rhizobial species, the effect of growth medium pH on cyo expression was tested. As the pH of the media was incrementally decreased, cyo expression gradually increased in the WT, eventually reaching ? 10-fold higher levels at low pH (4.8) compared with neutral pH (7.0) conditions. This upregulation of cyo under decreasing pH conditions was eliminated in the actSR mutant. Both the actSR and cyo mutants had severe growth defects at low pH (4.8). Lastly, the actSR and cyo mutants had severe growth defects when grown in media treated with an iron chelator. Under these conditions, cyo was upregulated in the WT, whereas cyo was not induced in the actSR mutant. Altogether, the results indicated cyo expression is largely dependent on the ActSR two-component system. This study also demonstrated additional physiological roles for Cyo in R. etli CFN42, in which it is the preferred oxidase for growth under acidic and low iron conditions. PMID:26297648

  12. Réponses physiologiques et biochimiques du trèfle (Trifolium alexandrinum L.) à la double association Mycorhizes-Rhizobium sous une contrainte saline

    Ben Khaled, Laaziza; Gõmez, Asunéion; Ouarraqi, El; Oihabi, Abdallah

    2003-01-01

    L'effet de la salinité (0, 4, 6 et 8 g NaCl $\\cdot$ L$^{-1}$) sur des plantules de trèfle (Trifolium alexandrinum L.) mycorhizées ou/et nodulées, cultivées sous serre sous une capacité au champ 75 %, a été estimé. La mycorhization par un inoculum mycorhizogène autochtone (MA) a abouti à une meilleure amélioration de la tolérance à la salinité et de la production de biomasse (+65 %) pour toutes les doses de sel appliquées. Les intensités de mycorhization et les teneurs en arbuscules obtenues p...

  13. Average nucleotide identity of genome sequences supports the description of Rhizobium lentis sp. nov., Rhizobium bangladeshense sp. nov. and Rhizobium binae sp. nov. from lentil (Lens culinaris) nodules.

    Rashid, M Harun-or; Young, J Peter W; Everall, Isobel; Clercx, Pia; Willems, Anne; Santhosh Braun, Markus; Wink, Michael

    2015-09-01

    Rhizobial strains isolated from effective root nodules of field-grown lentil (Lens culinaris) from different parts of Bangladesh were previously analysed using sequences of the 16S rRNA gene, three housekeeping genes (recA, atpD and glnII) and three nodulation genes (nodA, nodC and nodD), DNA fingerprinting and phenotypic characterization. Analysis of housekeeping gene sequences and DNA fingerprints indicated that the strains belonged to three novel clades in the genus Rhizobium. In present study, a representative strain from each clade was further characterized by determination of cellular fatty acid compositions, carbon substrate utilization patterns and DNA-DNA hybridization and average nucleotide identity (ANI) analyses from whole-genome sequences. DNA-DNA hybridization showed 50-62% relatedness to their closest relatives (the type strains of Rhizobium etli and Rhizobium phaseoli) and 50-60% relatedness to each other. These results were further supported by ANI values, based on genome sequencing, which were 87-92% with their close relatives and 88-89% with each other. On the basis of these results, three novel species, Rhizobium lentis sp. nov. (type strain BLR27(T) = LMG 28441(T) = DSM 29286(T)), Rhizobium bangladeshense sp. nov. (type strain BLR175(T) = LMG 28442(T) = DSM 29287(T)) and Rhizobium binae sp. nov. (type strain BLR195(T) = LMG 28443(T) = DSM 29288(T)), are proposed. These species share common nodulation genes (nodA, nodC and nodD) that are similar to those of the symbiovar viciae. PMID:26060217

  14. Change in land use alters the diversity and composition of Bradyrhizobium communities and led to the introduction of Rhizobium etli into the tropical rain forest of Los Tuxtlas (Mexico).

    Ormeño-Orrillo, Ernesto; Rogel-Hernández, Marco A; Lloret, Lourdes; López-López, Aline; Martínez, Julio; Barois, Isabelle; Martínez-Romero, Esperanza

    2012-05-01

    Nitrogen-fixing bacteria of the Bradyrhizobium genus are major symbionts of legume plants in American tropical forests, but little is known about the effects of deforestation and change in land use on their diversity and community structure. Forest clearing is followed by cropping of bean (Phaseolus vulgaris) and maize as intercropped plants in Los Tuxtlas tropical forest of Mexico. The identity of bean-nodulating rhizobia in this area is not known. Using promiscuous trap plants, bradyrhizobia were isolated from soil samples collected in Los Tuxtlas undisturbed forest, and in areas where forest was cleared and land was used as crop fields or as pastures, or where secondary forests were established. Rhizobia were also trapped by using bean plants. Bradyrhizobium strains were classified into genospecies by dnaK sequence analysis supported by recA, glnII and 16S-23S rDNA IGS loci analyses. A total of 29 genospecies were identified, 24 of which did not correspond to any described taxa. A reduction in Bradyrhizobium diversity was observed when forest was turned to crop fields or pastures. Diversity seemed to recover to primary forest levels in secondary forests that derived from abandoned crop fields or pastures. The shifts in diversity were not related to soil characteristics but seemingly to the density of nodulating legumes present at each land use system (LUS). Bradyrhizobium community composition in soils was dependent on land use; however, similarities were observed between crop fields and pastures but not among forest and secondary forest. Most Bradyrhizobium genospecies present in forest were not recovered or become rare in the other LUS. Rhizobium etli was found as the dominant bean-nodulating rhizobia present in crop fields and pastures, and evidence was found that this species was introduced in Los Tuxtlas forest. PMID:22109095

  15. Oligo- and polysaccharide synthesis by Rhizobium leguminosarum and Rhizobium meliloti.

    Breedveld, M W

    1992-01-01

    Rhizobium and Agrobacterium species are capable of synthesizing a variety of extracellular and cellular oligo- and polysaccharides. Changes in environmental conditions may all affect the composition, physical properties, and relative amounts of oligo- and polysaccharides. Interest in the field of Rhizobium polys accharides has resulted from a development in two distinct areas, (i) the role of oligo- and polysaccharides in the microbe- plant interaction, and (ii) studies on the physico- chemic...

  16. Effets de la double symbiose Rhizobium-Glomus spp. sur la croissance de Leucaena leucocephala (Lam. de Wit en pépinière, et dix mois après transplantation au Zaïre

    Bulakali, B.

    1992-01-01

    Full Text Available Effects of dual inoculation with Rhizobium and Glomus spp. on the growth of Leucaena leucocephala (Lam. de Wit in the nursery, and ten months after outplanting in Zaire. This work underlines the utility to inoculate in the nursery Leucaena leucocephala (Lam. de Wit, with efficient strains of Rhizobium and endomycorrhizal fungi, in order to ensure good initial plant growth after outplanting. In general, soil fumigation in the nursery allowed growth enhancement of control plants and the best effect of biofertilizers was obtained in the nursery and ten months after outplanting. Glomus vesiculiferum (Thaxter Gerdemann and Trappe associated or not with Rhizobium TAL 1145 likely produced the same effect by using natural soil in the nursery.

  17. Multiplication and Viability of some Rhizobium Strains to be used as Inoculants for Agricultural Biomass Production

    Simina Neo

    2012-05-01

    Full Text Available Rhizobia are well known for their capacity to establish a symbiosis with legumes. They inhabit root nodules, where they reduce atmospheric nitrogen and make it available to the plant. Biological nitrogen fixation is an important component of sustainable agriculture, and rhizobial inoculants have been applied frequently as biofertilizers. In this review we approach the subject of legumes inoculation in order to improve the nitrogen fixing capacity. In the first part of the experiment, the Rhizobium strains were cultivated on media indicated in the literature as optimal for bacterial growing and development in laboratory conditions. Afterwards, the Rhizobium strains that have grown and accumulate biomass were tested in different conditions of pH and salinity. The biomass accumulation was determinate by spectrophotometer. The obtained values shown that the Rhizobium strains tested can be used to inoculate the legumes cultivated on acid, basic and alkaline soils. Finally, the stability in real time of two strains of Rhizobium (Rhizobium meliloti and Rhizobium japonicum mixed with different supports was evaluated during a 6- months period. The supports studied were: peat, peat and calcium carbonate, zeolite, and ceramic. The highest number of viable cells at the end of the experiment was obtained in ceramic with Rhizobium japonicum (8x105 cells/gram, and the lowest number of viable cells was obtained in zeolite with Rhizobium meliloti (1,1x103 cells/gram.

  18. Tryptophan auxotrophs of Rhizobium japonicum.

    Wells, S E; Kuykendall, L D

    1983-01-01

    Eleven tryptophan-requiring mutants of Rhizobium japonicum I-110 ARS were isolated after nitrous acid mutagenesis and fell into five groups based on characterization by supplementation with intermediates and enzyme assays.

  19. Identification of the ???-Dependent Promoter Controlling Expression of the ansPAB Operon of the Nitrogen-Fixing Bacterium Rhizobium etli.

    Moreno-Enríquez, Angélica; Evangelista-Martínez, Zahaed; Servín-González, Luis; Flores-Carrasco, María Elena

    2015-08-01

    The aim of the present work was to examine the putative promoter region of the operon ansPAB and to determine the general elements required for the regulation of transcriptional activity. The transcriptional start site of the ansPAB promoter was determined by using highresolution S1-nuclease mapping. Sequence analysis of this region showed -10 and -35 elements, which were consistent with consensus sequences for R. etli promoters that are recognized by the major form of RNA polymerase containing the ?(70) transcription factor. Mutation studies affecting several regions located upstream of the transcriptional start site confirmed the importance of these elements on transcriptional expression. PMID:25839330

  20. Optimisation of inoculation of Leucaena leucocephala and Acacia mangium with rhizobium under greenhouse conditions

    Diouf, Diégane; Forestier, Sylvain; Neyra, Marc; Lesueur, Didier

    2003-01-01

    Optimisation de l'inoculation de Leucaena leucocephala et de Acacia mangium avec rhizobium en conditions de serre. Nos travaux ont porté sur l'optimisation de l'inoculation de 2 espèces agroforestières de légumineuses ligneuses : Leucaena leucocephala et Acacia mangium avec différentes souches de rhizobium. Tout d'abord, nous avons montré que le stade physiologique de la culture bactérienne n'a aucune influence sur la nodulation et la croissance des plants d'Acacia mangium inoculés et cultivé...

  1. Physiology of the Rhizobium-legume association

    Rhizobium deoxyribonucleic acid has been detected within Vicia faba root cells by in situ hybridization and autoradiography after exposure of root apexes to Rhizobium viable cells. Reannealed regions are localized in the cortex cells; the presence of bacterial DNA is specific for the root tissue; labelled regions were not detectable within apexes exposed to non-nodulating strains or to bacteria other than Rhizobium; Rhizobium DNA was not detectable in tissues of plants other than its leguminous host

  2. Nickel Availability and hupSL Activation by Heterologous Regulators Limit Symbiotic Expression of the Rhizobium leguminosarum bv. Viciae Hydrogenase System in Hup− Rhizobia

    Brito, Belén; Monza, Jorge; Imperial, Juan; Ruiz-Argüeso, Tomás; Palacios, Jose Manuel

    2000-01-01

    A limited number of Rhizobium and Bradyrhizobium strains possess a hydrogen uptake (Hup) system that recycles the hydrogen released from the nitrogen fixation process in legume nodules. To extend this ability to rhizobia that nodulate agronomically important crops, we investigated factors that affect the expression of a cosmid-borne Hup system from Rhizobium leguminosarum bv. viciae UPM791 in R. leguminosarum bv. viciae, Rhizobium etli, Mesorhizobium loti, and Sinorhizobium meliloti Hup− stra...

  3. Denitrification by Rhizobium meliloti

    Rosen, A.

    1996-10-01

    Rhizobium meliloti strains were investigated for their denitrification activity as free-living cells and in nodules on lucerne (Medicago sativa) roots. They were also investigated for presence of nitrous oxide reductase (nos) activity and for genes using a nosZ probe derived from the Pseudomonas stutzeri. To decide whether R. meliloti strains used as inoculants contribute to the total denitrification activity in a lucerne ley, strains with different denitrifying capacities were used in field and laboratory experiments. The nitrate reduction activity of R. meliloti during anaerobic respiration was compared with that of a strain of Pseudomonas aeruginosa. A great diversity in the denitrification activity was found within strains of R. meliloti, and four of thirteen investigated strains showed an obvious denitrification activity. Two denitrifying bacteria were used as references, one strain each of Bradyrhizobium japonicum and P. aeruginosa. All but one of the R. meliloti strains hybridized to the PstI-fragment of the nosZ-gene from P. stutzeri. Two sizes of the hybridizing fragment, 5 and 7 kb, were noticed. Nos activity was only shown in three R. meliloti strains, and these were all characterized by a high denitrification activity. The potential denitrification activity was about 20, 40, and 80 times higher than the actual denitrification activity for lucerne, fallow, and grass, respectively. The potential denitrification activity was almost the same in lucerne and grass planted soils. Compared with the unplanted soil, the presence of lucerne roots in the soil increased the actual denitrification activity, while roots of both plant species, grass and lucerne, increased the potential denitrification activity in the soil. 32 refs, 7 figs, 1 tab

  4. Peritonitis due to Rhizobium radiobacter

    Marta, R; Dâmaso, C; Silva, JE; M.De Almeida

    2011-01-01

    Rhizobium radiobacter (Agrobacterium radiobacter) is an aerobic Gram-negative rod belonging to Agrobacterium genus, a group of phytopathogenic bacteria present in the soil that has been implicated in human opportunistic infections. We report a clinical case of bacterial peritonitis in a 5-year-old child with chronic renal disease in peritoneal dialysis, who had a history of direct soil contact identified. The infection was treated with ceftazidime and piperaciline+tazobactam without relapses ...

  5. Group-specific differentiation of Rhizobium from clover species by PCR amplification of 23S rDNA sequences.

    Tesfaye, M; Holl, F B

    1998-11-01

    Two 20-bp primers that provide group-specific detection of Rhizobium spp. by polymerase chain reaction (PCR) have been used to differentiate strains that belong to different effectiveness groups within the Rhizobium-Trifolium cross-inoculation group. The target for DNA amplification was a 370-bp fragment of the 23S rDNA region. Analysis of additional root-nodule forming, as well as root-associated bacterial species by PCR-primer assay revealed that variability within this 20-bp segment of the 23S rDNA region may be widespread and provide an effective identification tool. Our data suggest that strains of Rhizobium isolated from the perennial clover Trifolium semipilosum may be phylogenetically more closely related to Rhizobium etli. PMID:10030005

  6. Evolutionary origin of rhizobium Nod factor signaling

    Streng, A.; Camp, R., van de; Bisseling, T.; R. Geurts

    2011-01-01

    For over two decades now, it is known that the nodule symbiosis between legume plants and nitrogen fixing rhizobium bacteria is set in motion by the bacterial signal molecule named nodulation (Nod) factor.1 Upon Nod factor perception a signaling cascade is activated that is also essential for endomycorrhizal symbiosis (Fig. 1). This suggests that rhizobium co-opted the evolutionary far more ancient mycorrhizal signaling pathway in order to establish an endosymbiotic interaction with legumes.2...

  7. Effect of Plasmid pIJ1008 from Rhizobium leguminosarum on Symbiotic Function of Rhizobium meliloti

    E.J Bedmar; Brewin, N J; Phillips, D A

    1984-01-01

    Plasmid pIJ1008, which carries determinants for uptake hydrogenase (Hup) activity, was transferred from Rhizobium leguminosarum to Rhizobium meliloti without impairing the capacity of the latter species to form root nodules on alfalfa. The plasmid was still present in rhizobia reisolated from the root nodules of 12 different alfalfa cultivars, but only low levels of Hup activity were detected in alfalfa.

  8. Expressão dos genes nod de Rhizobium tropici, R. etli e R. leguminosarum bv. phaseoli e estabelecimento da nodulação do feijoeiro na presença de exsudatos de sementes de Mimosa flocculosa e Leucaena leucocephala

    F. M. Mercante

    2000-06-01

    Full Text Available Na etapa inicial da troca de sinais moleculares entre macro e microssimbiontes, a interação do feijoeiro e estirpes de Rhizobium tropici, R. etli e R. leguminosarum bv. phaseoli foi avaliada pela expressão dos genes nod de estirpes bacterianas, contendo a fusão nodA::gusA. Esta avaliação foi efetuada por meio da atividade da enzima ß-glucuronidase, utilizando, como indutores, exsudatos liberados pelas sementes de Mimosa flocculosa e Leucaena leucocephala. Além disso, avaliou-se o efeito da adição desses exsudatos no estabelecimento da nodulação do feijoeiro, cv. Carioca. Nos testes "in vitro", a mistura de exsudatos de sementes de feijoeiro e M. flocculosa promoveu aumentos sinergísticos significativos na expressão dos genes nod, tanto das estirpes de R. tropici (CIAT 899/pGUS 32 e F 98.5/pGUS 32 quanto de R. etli (CFN 42/pGUS 32. Em condições controladas, a adição dos exsudatos, tanto de M. flocculosa quanto de L. leucocephala, proporcionou aumento significativo na nodulação inicial do feijoeiro, quando foi inoculada a estirpe CFN 42 (R. etli. A nodulação do feijoeiro cultivado em vasos com solo não foi inibida pelo suprimento de N-mineral, quando se inoculou a estirpe CIAT 899 (R. tropici e foram fornecidos exsudatos de sementes de M. flocculosa.

  9. Genes Essential for Nod Factor Production and Nodulation Are Located on a Symbiotic Amplicon (AMPRtrCFN299pc60) in Rhizobium tropici

    Mavingui, Patrick; Laeremans, Toon; Flores, Margarita; Romero, David; Martínez-Romero, Esperanza; Palacios, Rafael

    1998-01-01

    Amplifiable DNA regions (amplicons) have been identified in the genome of Rhizobium etli. Here we report the isolation and molecular characterization of a symbiotic amplicon of Rhizobium tropici. To search for symbiotic amplicons, a cartridge containing a kanamycin resistance marker that responds to gene dosage and conditional origins of replication and transfer was inserted in the nodulation region of the symbiotic plasmid (pSym) of R. tropici CFN299. Derivatives harboring amplifications wer...

  10. En route vers la nano stabilisation de CLIC faisceau principale et focalisation finale

    Artoos, K; Guinchard, M; Hauviller, Claude; Lackner, F; CERN. Geneva. TS Department

    2008-01-01

    Pour atteindre la luminosité voulue de CLIC, la taille transversale du faisceau doit être de l?ordre du nanomètre. Ceci nécessite une stabilité vibratoire des quadripôles du faisceau principal de 1 nm et même 0.1 nm pour les doublets de la focalisation finale. La nano technologie et la nano stabilisation sont des activités qui évoluent rapidement dans l?industrie et centres de recherche pour des applications très variées comme l?électronique, l?optique, la chimie voire la médecine. Cette présentation décrit les avancées techniques nécessaires pour atteindre l?objectif de CLIC et les projets et collaborations R&D prévus pour démontrer la faisabilité de la nano stabilisation de CLIC en 2010.

  11. Optimization of Dairy Sludge for Growth of Rhizobium Cells

    Ashok Kumar Singh; Gauri Singh; Digvijay Gautam; Manjinder Kaur Bedi

    2013-01-01

    In this study dairy sludge was evaluated as an alternative cultivation medium for Rhizobium. Growth of bacterial strains at different concentrations of Dairy sludge was monitored. Maximum growth of all strains was observed at 60% Dairy sludge concentration. At 60% optical density (OD) values are 0.804 for Rhizobium trifolii (MTCC905), 0.825 for Rhizobium trifolii (MTCC906), and 0.793 for Rhizobium meliloti (MTCC100). Growth pattern of strains was observed at 60% Dairy sludge along with differ...

  12. 76 FR 68210 - United States v. George's Foods, LLC, et al.; Public Comment and Response on Proposed Final Judgment

    2011-11-03

    ... United States v. George's Foods, Inc., et. al., 76 FR 38419; and summaries of the terms of the proposed... Antitrust Division United States v. George's Foods, LLC, et al.; Public Comment and Response on Proposed Final Judgment Pursuant to the Antitrust Procedures and Penalties Act, 15 U.S.C. 16(b)-(h), the...

  13. Rhizobium meliloti mutants altered in ammonium utilization.

    Osburne, M S

    1982-01-01

    Derivatives of Rhizobium meliloti 2011 required trace amounts of glutamate to use ammonium as the nitrogen source for growth, although they could use serine as the sole nitrogen source. Specific activities of ammonium assimilatory enzymes were similar to those in strain Rm2011. The mutants were deficient in nitrogen fixation.

  14. Congo Red Absorption by Rhizobium leguminosarum

    Kneen, Barbara E.; LaRue, Thomas A.

    1983-01-01

    Congo red absorption is generally considered a contraindication of Rhizobium. However, R. leguminosarum takes up the dye on yeast extract-mannitol agar. The uptake of congo red varies among strains of R. leguminosarum, as shown elsewhere with strains of R. trifolii and R. meliloti. Congo red absorption does not distinguish rhizobia from other bacteria, but may be useful as a strain marker.

  15. Rhizobium ecuadorense sp. nov., an indigenous N2-fixing symbiont of the Ecuadorian common bean (Phaseolus vulgaris L.) genetic pool.

    Ribeiro, Renan Augusto; Martins, Talita Busulini; Ormeño-Orrillo, Ernesto; Marçon Delamuta, Jakeline Renata; Rogel, Marco Antonio; Martínez-Romero, Esperanza; Hungria, Mariangela

    2015-09-01

    There are two major centres of genetic diversification of common bean (Phaseolus vilgaris L.), the Mesoamerican and the Andean, and the legume is capable of establishing nitrogen-fixing symbioses with several rhizobia; Rhizobium etli seems to be the dominant species in both centres. Another genetic pool of common bean, in Peru and Ecuador, is receiving increasing attention, and studies of microsymbionts from the region can help to increase our knowledge about coevolution of this symbiosis. We have previously reported several putative new lineages from this region and here present data indicating that strains belonging to one of them, PEL4, represent a novel species. Based on 16S rRNA gene sequence phylogeny, PEL4 strains are positioned in the Rhizobium phaseoli/R. etli/Rhizobium leguminosarum clade, but show unique properties in several morphological, physiological and biochemical analyses, as well as in BOX-PCR profiles (?fixing N2 with common beans. The data supported the view that PEL4 strains represent a novel species, Rhizobium ecuadorense sp. nov. The type strain is CNPSo 671(T) (?= UMR 1450(T) = PIMAMPIRS I 5(T) = LMG 27578(T)). PMID:26297041

  16. Recognition of Leguminous Hosts by a Promiscuous Rhizobium Strain

    Shantharam, S; Wong, Peter P.

    1982-01-01

    The lima bean (Phaseolus lunatus L.) and the pole bean (Phaseolus vulgaris L.) are nodulated by rhizobia of two different cross-inoculation groups. Rhizobium sp. 127E15, a cowpea-type Rhizobium, can induce effective nodules on the lima bean and partially effective nodules on the pole bean. Rhizobium phaseoli 127K14 can induce effective nodules on the pole bean but does not reciprocally nodulate the lima bean. Root hairs of the lima bean when inoculated with Rhizobium sp. 127E15 showed tip cur...

  17. Some properties of the nickel-containing hydrogenase of chemolithotrophically grown Rhizobium japonicum.

    Harker, A. R.; Xu, L.S.; Hanus, F. J.; Evans, H.J.

    1984-01-01

    The uptake hydrogenase of chemolithotrophically grown Rhizobium japonicum was purified to apparent homogeneity with a final specific activity of 69 mumol of H2 oxidized per min per mg of protein. The procedure included Triton extraction of broken membranes and DEAE-cellulose and Sephacryl S-200 chromatographies. The purified protein contained two polypeptides separable only by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. They comigrated on native polyacrylamide gels and sucrose ...

  18. Evolutionary origin of rhizobium Nod factor signaling.

    Streng, Arend; op den Camp, Rik; Bisseling, Ton; Geurts, René

    2011-10-01

    For over two decades now, it is known that the nodule symbiosis between legume plants and nitrogen fixing rhizobium bacteria is set in motion by the bacterial signal molecule named nodulation (Nod) factor. Upon Nod factor perception a signaling cascade is activated that is also essential for endomycorrhizal symbiosis (Fig. 1). This suggests that rhizobium co-opted the evolutionary far more ancient mycorrhizal signaling pathway in order to establish an endosymbiotic interaction with legumes. As arbuscular mycorrhizal fungi of the Glomeromycota phylum can establish a symbiosis with the fast majority of land plants, it is most probable that this signaling cascade is wide spread in plant kingdom. However, Nod factor perception generally is considered to be unique to legumes. Two recent breakthroughs on the evolutionary origin of Rhizobium Nod factor signaling demonstrate that this is not the case. The purification of Nod factor-like molecules excreted by the mycorrhizal fungus Glomus intraradices and the role of the LysM-type Nod factor receptor PaNFP in the non-legume Parasponia andersonii provide novel understanding on the evolution of rhizobial Nod factor signaling. PMID:21904113

  19. Biodegradation of Phosphonomycin by Rhizobium huakuii PMY1

    McGrath, John W.; Hammerschmidt, Friedrich; Quinn, John P.

    1998-01-01

    The biodegradation by Rhizobium huakuii PMY1 of up to 10 mM phosphonomycin as a carbon, energy, and phosphorus source with accompanying Pi release is described. This biodegradation represents a further mechanism of resistance to this antibiotic and a novel, phosphate-deregulated route for organophosphonate metabolism by Rhizobium spp.

  20. 75 FR 33637 - United States v. Bemis Company, Inc., et al.; Public Comments and Response on Proposed Final...

    2010-06-14

    .... Bemis Company, Inc. et al., 75 FR 9929; and published summaries of the terms of the proposed Final..., Inc., 858 F.2d 456, 462 (9th Cir. 1988) (citing United States v. Bechtel Corp., 648 F.2d 660, 666 (9th... decree. Bechtel, 648 F.2d at 666 (emphasis added) (citations omitted).\\4\\ In determining whether...

  1. Rhizobium daejeonense sp. nov. isolated from a cyanide treatment bioreactor.

    Quan, Zhe-Xue; Bae, Hee-Sung; Baek, Jong-Hwan; Chen, Wen-Feng; Im, Wan-Taek; Lee, Sung-Taik

    2005-11-01

    A polyphasic study was carried out to determine the taxonomic position of two aerobic, cyanide-degrading bacterial strains, designated L61T and L22, which had been isolated from a bioreactor for the treatment of nickel-complexed cyanide. The two isolates exhibited almost identical taxonomic characteristics. Phylogenetic analysis inferred from comparative 16S rRNA gene sequences indicated that the isolates fall in a sublineage of the genus Rhizobium comprising the type strains of Rhizobium giardinii, Rhizobium radiobacter, Rhizobium rubi, Rhizobium larrymoorei, Rhizobium vitis, Rhizobium undicola, Rhizobium loessense, Rhizobium galegae and Rhizobium huautlense. Cells of the two isolates are Gram-negative, aerobic, motile and non-spore-forming rods (0.6-0.7x1.1-1.3 microm), with peritrichous flagella. The DNA G+C content is 60.1-60.9 mol%. Cellular fatty acids are C(16 : 0) (2.2-3.3 %), C(18 : 0) (2.1-3.2 %), C(19 : 0) cyclo omega8c (9.9-16.8 %), C(20 : 3)omega6,9,12c (2.7-3.3 %), summed feature 3 (7.2-7.7 %) and summed feature 7 (67.8-73.7 %). The strains formed nodules on a legume plant, Medicago sativa. A nifH gene encoding denitrogenase reductase, the key component of the nitrogenase enzyme complex, was detected in L61T by PCR amplification by using a nifH-specific primer system. Strains L61T and L22 were distinguished from the type strains of recognized Rhizobium species in the same sublineage based on low DNA-DNA hybridization values (2-4 %) and/or a 16S rRNA gene sequence similarity value of less than 96 %. Moreover, some phenotypic properties with respect to substrate utilization as a carbon or nitrogen source, antibiotic resistance and growth conditions could be used to discriminate L61T and L22 from Rhizobium species in the same sublineage. Based on the results obtained in this study, L61T and L22 are considered to be representatives of a novel species of Rhizobium, for which the name Rhizobium daejeonense sp. nov. is proposed. The type strain is L61T (=KCTC 12121T=IAM 15042T=CCBAU 10050T). PMID:16280524

  2. Characterization of the nodulation plasmid encoded chemoreceptor gene mcpG from Rhizobium leguminosarum

    Del Bel Kate L

    2003-01-01

    Full Text Available Abstract Background In general, chemotaxis in Rhizobium has not been well characterized. Methyl accepting chemotaxis proteins are sensory proteins important in chemotaxis of numerous bacteria, but their involvement in Rhizobium chemotaxis is unclear and merits further investigation. Results A putative methyl accepting chemotaxis protein gene (mcpG of Rhizobium leguminosarum VF39SM was isolated and characterized. The gene was found to reside on the nodulation plasmid, pRleVF39d. The predicted mcpG ORF displayed motifs common to known methyl-accepting chemotaxis proteins, such as two transmembrane domains and high homology to the conserved methylation and signaling domains of well-characterized MCPs. Phenotypic analysis of mcpG mutants using swarm plates did not identify ligands for this putative receptor. Additionally, gene knockouts of mcpG did not affect a mutant strain's ability to compete for nodulation with the wild type. Notably, mcpG was found to be plasmid-encoded in all strains of R. leguminosarum and R. etli examined, though it was found on the nodulation plasmid only in a minority of strains. Conclusions Based on sequence homology R. leguminosarum mcpG gene codes for a methyl accepting chemotaxis protein. The gene is plasmid localized in numerous Rhizobium spp. Although localized to the sym plasmid of VF39SM mcpG does not appear to participate in early nodulation events. A ligand for McpG remains to be found. Apparent McpG orthologs appear in a diverse range of proteobacteria. Identification and characterization of mcpG adds to the family of mcp genes already identified in this organism.

  3. (A structural assessment of the role of the cell surface carbohydrates of Rhizobium in the Rhizobium/legume symbiosis)

    Hollingsworth, R.I.

    1991-01-01

    Research continued on the study of cell surface carbohydrates of Rhizobium. Objectives include: To characterize, at a structural level, the differences between the lipopolysaccharides of a representative number of strains from different Rhizobium species to determine which features of LPS structure are species-specific and might, therefore, be determinants of host specificity. Determine the effect(s) of nod gene induction on the structure of Rhizobium lipopolysaccharides and determine whether synthesis of a modified LPS molecule or a new surface glycoconjugate is initiated by nod gene induction. Develop a non-chemical means for rapidly screening large numbers of bacterial strains in order to determine which glycoconjugate structural features are conserved between strains of the same species. Provide the necessary structural information which, when coupled with developments in the rapidly expanding field of Rhizobium genetics, should lead to a clear understanding of the role of Rhizobium surface glycoconjugates in host/symbiont interactions. Progress is discussed.

  4. Nodulation of Acacia species by fast-and slow-growing tropical strains of Rhizobium

    Dreyfus, B. L.; Dommergues, Y. R.

    1981-01-01

    Thirteen Acacia species were classified into three groups according to effective nodulation response patterns with fast- and slow-growing tropical strains of Rhizobium. The first group nodulated effectively with slow-growing, cowpea-type Rhizobium strains; the second, with fast-growing Rhizobium strains; and the third, with both fast- and slow-growing Rhizobium strains. The Rhizobium requirements of the Acacia species of the second group were similar to those of Leucaena leucocephala.

  5. Interaction Between the Biotin Carboxyl Carrier Domain and the Biotin Carboxylase Domain in Pyruvate Carboxylase from Rhizobium etli†

    Lietzan, Adam D.; Menefee, Ann L.; Zeczycki, Tonya N.; Kumar, Sudhanshu; Attwood, Paul V.; Wallace, John C.; Cleland, W. Wallace; Maurice, Martin St.

    2011-01-01

    Pyruvate carboxylase (PC) catalyzes the ATP-dependent carboxylation of pyruvate to oxaloacetate, an important anaplerotic reaction in mammalian tissues. To effect catalysis, the tethered biotin of PC must gain access to active sites in both the biotin carboxylase domain and the carboxyl transferase domain. Previous studies have demonstrated that a mutation of threonine 882 to alanine in PC from Rhizobium etli renders the carboxyl transferase domain inactive and favors the positioning of bioti...

  6. Rhizobium calliandrae sp. nov., Rhizobium mayense sp. nov. and Rhizobium jaguaris sp. nov., rhizobial species nodulating the medicinal legume Calliandra grandiflora.

    Rincón-Rosales, Reiner; Villalobos-Escobedo, José M; Rogel, Marco A; Martinez, Julio; Ormeño-Orrillo, Ernesto; Martínez-Romero, Esperanza

    2013-09-01

    Calliandra grandiflora has been used as a medicinal plant for thousands of years in Mexico. Rhizobial strains were obtained from root nodules of C. grandiflora collected from different geographical regions in Chiapas and characterized by BOX-PCR, amplified rDNA restriction analysis (ARDRA) and 16S rRNA gene sequence analysis. Most isolates corresponded to members of the genus Rhizobium and those not related to species with validly published names were further characterized by recA, atpD, rpoB and nifH gene phylogenies, phenotypic and DNA-DNA hybridization analyses. Three novel related species of the genus Rhizobium within the 'Rhizobium tropici group' share the same symbiovar that may be named sv. calliandrae. The names proposed for the three novel species are Rhizobium calliandrae sp. nov. (type strain, CCGE524(T) =ATCC BAA-2435(T) =CIP 110456(T) =LBP2-1(T)), Rhizobium mayense sp. nov. (type strain, CCGE526(T) =ATCC BAA-2446(T) = CIP 110454(T) =NSJP1-1(T)) and Rhizobium jaguaris sp. nov. (type strain, CCGE525(T) =ATCC BAA-2445(T) =CIP 110453(T) =SJP1-2(T)). PMID:23584283

  7. D'une ouverture de la voyelle /epsilon/ en finale absolue en francais quebecois : analyse acoustique et perceptive

    Riverin-Coutlee, Josiane

    Cette contribution est consacree a l'ouverture du /epsilon/ en finale absolue, un phenomene phonetique repute etre en declin en francais quebecois et caracteristique de locuteurs âges, peu scolarises, issus de milieux populaires et s'exprimant en situation de communication informelle. Une analyse acoustique de 480 voyelles /epsilon/ issues de la parole formelle de 40 jeunes etudiants universitaires originaires des centres urbains de Saguenay et de Quebec revele toutefois que le phenomene est encore bien vivant en francais quebecois et qu'il est plus frequent chez les locuteurs de Saguenay, une tendance validee auditivement par accord inter-juges. Les resultats d'un test de discrimination et d'identification mene aupres de 26 etudiants universitaires originaires de ces deux memes villes indiquent que les auditeurs naifs de Saguenay semblent moins sensibles a la variation et moins enclins a juger de l'origine geographique d'un locuteur a partir de sa prononciation de la voyelle /epsilon/ en fin de mot.

  8. Rhizobium leguminosarum mutants incapable of normal extracellular polysaccharide production.

    Napoli, C; Albersheim, P

    1980-01-01

    Mutants of Rhizobium leguminosarum which are deficient in normal polysaccharide production have been isolated and characterized. A correlation between diminished production of extracellular polysaccharide and reduced infection and nodulation efficiency has been observed.

  9. Comparative properties of glutamine synthetases I and II in Rhizobium and Agrobacterium spp.

    Fuchs, R L; Keister, D L

    1980-01-01

    Some properties of glutamine synthetase I (GSI) and GSII are described for a fast-growing Rhizobium sp. (Rhizobium trifolii T1), a slow-growing Rhizobium sp. (Rhizobium japonicum USDA 83), and Agrobacterium tumefaciens C58. GSII of the fast-growing Rhizobium sp. and GSII of the Agrobacterium sp. were considerably more heat labile than GSII of the slow-growing Rhizobium sp. As previously shown in R. japonicum 61A76, GSI became adenylylated rapidly in all species tested in response to ammonium....

  10. Factors Affecting the Efficiency of Symbiotic Nitrogen Fixation by Rhizobium

    Abdullah M. K. Al-Falih

    2002-01-01

    Recent reports pointed to a decline in agricultural dependence on symbiotic nitrogen fixation, and in the use of rhizobial inoculants. The aim of the present review was to study the environmental factors that affect the efficiency of symbiotic nitrogen fixation by Rhizobium in soil. These factors included pH, salinity, moisture, temperature, microorganisms, organic matter and soil texture. The overall conclusion is that symbiotic nitrogen fixation by Rhizobium is a critical biological process...

  11. Reiterated DNA Sequences in Rhizobium and Agrobacterium spp

    Flores, M.; González, V.; Brom, S; Martínez, E.; Piñero, D; Romero, D.; Dávila, G; Palacios, R

    1988-01-01

    Repeated DNA sequences are a general characteristic of eucaryotic genomes. Although several examples of DNA reiteration have been found in procaryotic organisms, only in the case of the archaebacteria Halobacterium halobium and Halobacterium volcanii [C. Sapienza and W. F. Doolittle, Nature (London) 295:384-389, 1982], has DNA reiteration been reported as a common genomic feature. The genomes of two Rhizobium phaseoli strains, one Rhizobium meliloti strain, and one Agrobacterium tumefaciens s...

  12. Synergy between Rhizobium phaseoli and Acidithiobacillus ferrooxidans in the Bioleaching Process of Copper

    Xuecheng Zheng; Dongwei Li

    2016-01-01

    This study investigates the synergy of Rhizobium phaseoli and Acidithiobacillus ferrooxidans in the bioleaching process of copper. The results showed that additional R. phaseoli could increase leaching rate and cell number of A. ferrooxidans. When the initial cell number ratio between A. ferrooxidans and R. phaseoli was 2 : 1, A. ferrooxidans attained the highest final cell number of approximately 2 × 108 cells/mL and the highest copper leaching rate of 29%, which is 7% higher than that in th...

  13. Delayed maturation of nodules reduces symbiotic effectiveness of the Lotus japonicus–Rhizobium sp. NGR234 interaction

    Schumpp, Olivier; Crèvecoeur, Michèle; Broughton, William John; Deakin, William James

    2008-01-01

    Lotus japonicus, a model legume, develops an efficient, nitrogen-fixing symbiosis with Mesorhizobium loti that promotes plant growth. Lotus japonicus also forms functional nodules with Rhizobium sp. NGR234 and R. etli. Yet, in a plant defence-like reaction, nodules induced by R. etli quickly degenerate, thus limiting plant growth. In contrast, nodules containing NGR234 are long-lasting. It was found that NGR234 initiates nodule formation in a similar way to M. loti MAFF303099, but that the no...

  14. Rhizobium helianthi sp. nov., isolated from the rhizosphere of sunflower.

    Wei, Xuexin; Yan, Shouwei; Li, Dai; Pang, Huancheng; Li, Yuyi; Zhang, Jianli

    2015-12-01

    A Gram-stain-negative, non-spore-forming, rod-shaped and aerobic bacterium, designated Xi19T, was isolated from a soil sample collected from the rhizosphere of sunflower (Helianthus annuus) in Wuyuan county of Inner Mongolia, China and was characterized taxonomically by using a polyphasic approach. Phylogenetic analysis based on 16S rRNA gene sequences indicated that the novel isolate was related to species of the genus Rhizobium, sharing the greatest 16S rRNA gene sequence similarity with Rhizobium rhizoryzae J3-AN59T (98.4 %), followed by Rhizobium pseudoryzae J3-A127T (97.4 %). There were low similarities ( Rhizobium. DNA-DNA hybridization values between strain Xi19T and the most related strain Rhizobium rhizoryzae J3-AN59T were low. The major cellular fatty acids of strain Xi19T were C16 : 0, summed feature 8 (C18 : 1ω7c and/or C18 : 1ω6c) and C19 : 0 cyclo ω8c. Q-10 was identified as the predominant ubiquinone and the major polar lipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine and phosphatidylcholine. The DNA G+C content of strain Xi19T was 60.2 mol%. On the basis of physiological and biochemical characteristics, coupled with genotypic data obtained in this work, strain Xi19T represents a novel species of the genus Rhizobium, for which the name Rhizobium helianthi is proposed. The type strain is Xi19T ( = CGMCC 1.12192T = KCTC 23879T). PMID:26364048

  15. 75 FR 76026 - United States v. Graftech International Ltd., Et al.; Proposed Final Judgment and Competitive...

    2010-12-07

    ... could provide GrafTech (and hence Seadrift) with inappropriate competitive information regarding pricing... Competitive Impact Statement Notice is hereby given pursuant to the Antitrust Procedures and Penalties Act, 15 U.S.C. 16(b)-(h), that a proposed Final Judgment, Stipulation and Competitive Impact Statement...

  16. The beneficial effect of dual inoculation of vesicular-arbuscular mycorrhizae + rhizobium on growth of white clover

    Lin, XG.

    1993-01-01

    Full Text Available Investigation on the effect of phosphorus on vesicular-arbuscular mycorrhizal infection, and dual inoculation of vesicular-arbuscular mycorrhizae + rhizobium on growth of white clover under field microplots and pot experiments was conducted on fluvo-aquic soils of semi-arid region in north China. The results showed that 60 kg P205 ha in form of superphosphate was the most favorable phosphorus level for vesicular-arbuscular mycorrhizal infection ; mycorrhizal infection, nodulation, dry weight of shoots and roots, total uptake of nitrogen, phosphorus and other elements, the final yields and recovery of phosphorus of white clover were significantly increased by vesicular-arbuscular mycorrhizal inoculation and dual inoculation with vesicular-arbuscular mycorrhizal fungi and rhizobium. The highest response of inoculation was obtained by adding fertilizer phosphorus at the level of 60 kg P205 ha in form of superphosphate.

  17. Production of Poly-b-Hydroxybutyrate (PHB) by Some Rhizobium Bacteria

    MERCAN, Nazime

    2002-01-01

    In this study, the production of Poly-b-hydroxybutyrate (PHB) was determined in 1 Rhizobium japonicum, 6 Rhizobium cicer, 8 Rhizobium spp. and Bradyrhizobium japonicum USDA 110. The content of according to dry cell weight was determined to be 1.38-40.0%. In our study, Rhizobium spp. 2426, which produced the highest percentage yield of PHB, and Rhizobium spp. 640, which produced the intermediate percentage yield of PHB, were first selected among all the strains, and then the effect of differen...

  18. Physiological role of calcium in legume-rhizobium symbiosis

    Vasil’eva G.G.

    2011-12-01

    Full Text Available Literature data on the physiological role of calcium (Ca2+ in legume-rhizobium symbiosis development on initial stages - the infection and symbiotic structures formation, are generalized. The questions about the Ca2+ function in plants, special feature the formation of legume-rhizobium symbiosis and role of calcium in the interaction of two organisms are considered. Data on the interaction of ROS and Ca2+ in the development of the legume-rhizobium symbiosis and the relationship of NADPH-oxidase activity with the calcium signaling system are analyzed. The special attention is given to the role of Ca22+-spiking and calcium and calmodulin-like kinase in the initiation of plant symbiotic ways operation leads to infection and the formation of symbiotic structures.

  19. [LEGUME-RHIZOBIUM SYMBIOSIS PROTEOMICS: ACHIEVEMENTS AND PERSPECTIVES].

    Kondratiuk, Iu Iu; Mamenko, P M; Kots, S Ya

    2015-01-01

    The present review contains results of proteomic researches of legume-rhizobium symbiosis. The technical difficulties associated with the methods of obtaining protein extracts from symbiotic structures and ways of overcoming them were discussed. The changes of protein synthesis under formation and functioning of symbiotic structures were shown. Special attention has been given to the importance of proteomic studies of plant-microbe structures in the formation of adaptation strategies under adverse environmental conditions. The technical and conceptual perspectives of legume-rhizobium symbiosis proteomics were shown. PMID:26717593

  20. Rhizobium sophorae sp. nov. and Rhizobium sophoriradicis sp. nov., nitrogen-fixing rhizobial symbionts of the medicinal legume Sophora flavescens.

    Jiao, Yin Shan; Yan, Hui; Ji, Zhao Jun; Liu, Yuan Hui; Sui, Xin Hua; Wang, En Tao; Guo, Bao Lin; Chen, Wen Xin; Chen, Wen Feng

    2015-02-01

    Five bacterial strains representing 45 isolates originated from root nodules of the medicinal legume Sophora flavescens were defined as two novel groups in the genus Rhizobium based on their phylogenetic relationships estimated from 16S rRNA genes and the housekeeping genes recA, glnII and atpD. These groups were distantly related to Rhizobium leguminosarum USDA 2370(T) (95.6 % similarity for group I) and Rhizobium phaseoli ATCC 14482(T) (93.4 % similarity for group II) in multilocus sequence analysis. In DNA-DNA hybridization experiments, the reference strains CCBAU 03386(T) (group I) and CCBAU 03470(T) (group II) showed levels of relatedness of 17.9-57.8 and 11.0-42.9 %, respectively, with the type strains of related species. Both strains CCBAU 03386(T) and CCBAU 03470(T) contained ubiquinone 10 (Q-10) as the major respiratory quinone and possessed 16 : 0, 18 : 0, 19 : 0 cyclo ?8c, summed feature 8 and summed feature 2 as major fatty acids, but did not contain 20 : 3 ?6,8,12c. Phenotypic features distinguishing both groups from all closely related species of the genus Rhizobium were found. Therefore, two novel species, Rhizobium sophorae sp. nov. for group I (type strain CCBAU 03386(T)?= E5(T)?= LMG 27901(T)?= HAMBI 3615(T)) and Rhizobium sophoriradicis sp. nov. for group II (type strain CCBAU 03470(T)?= C-5-1(T)?= LMG 27898(T)?= HAMBI 3510(T)), are proposed. Both groups were able to nodulate Phaseolus vulgaris and their hosts of origin (Sophora flavescens) effectively and their nodulation gene nodC was phylogenetically located in the symbiovar phaseoli. PMID:25385989

  1. Identification of Rhizobium-specific intergenic mosaic elements within an essential two-component regulatory system of Rhizobium species.

    Osterås, M; Stanley, J; Finan, T. M.

    1995-01-01

    Analysis of the DNA regions upstream of the phosphoenolpyruvate carboxykinase gene (pckA) in Rhizobium meliloti and Rhizobium sp. strain NGR234 identified an open reading frame which was highly homologous to the Agrobacterium tumefaciens chromosomal virulence gene product ChvI. A second gene product, 500 bp downstream of the chvI-like gene in R. meliloti, was homologous to the A. tumefaciens ChvG protein. The homology between the R. meliloti and A. tumefaciens genes was confirmed, because the...

  2. Conservation of nodulation genes between Rhizobium meliloti and a slow-growing Rhizobium strain that nodulates a nonlegume host

    Marvel, Deborah J.; Kuldau, Gretchen; Hirsch, Ann; Richards, Eric; Torrey, John G.; Ausubel, Frederick M.

    1985-01-01

    Parasponia, a woody member of the elm family, is the only nonlegume genus whose members are known to form an effective nitrogen-fixing symbiosis with a Rhizobium species. The bacterial strain RP501 is a slow-growing strain of Rhizobium isolated from Parasponia nodules. Strain RP501 also nodulates the legumes siratro (Macroptilium atropurpureum) and cowpea (Vigna unguiculata). Using a cosmid clone bank of RP501 DNA, we isolated a 13.4-kilobase (kb) EcoRI fragment that complemented insertion an...

  3. A rhizobium selenitireducens protein showing selenite reductase activity

    Biobarriers remove, via precipitation, the metalloid selenite (SeO3–2) from groundwater; a process that involves the biological reduction of soluble SeO3–2 to insoluble elemental red selenium (Se0). The enzymes associated with this reduction process are poorly understood. In Rhizobium selenitiredu...

  4. Strain identification in Rhizobium by starch gel electrophoresis of isoenzymes

    Engvild, Kjeld Christensen; Nielsen, G.

    1985-01-01

    Sonieated extracts of rhizobia, especiaUy Rhizobium leguminosarum from pea and vetch, were run in horizontal starch gel electrophoresis in the cold. The rhizobia were grown on agar on a slime suppressing substrate of tryptone-yeast extract-CaCl2 with small amounts of mannitol, sorbitol and...

  5. Diversity of Rhizobium leguminosarum from pea fields in Washington State

    Rhizobia-mediated biological nitrogen (N) fixation in legumes contributes to yield potential in these crops and also provides residual fertilizer to subsequent cereals. Our objectives were to collect isolates of Rhizobium leguminosarum from several pea fields in Washington, examine genetic diversity...

  6. Inoculação com Rhizobium e aplicação de nitrogênio em amendoim Comparison among Rhizobium strains inoculations and nitrogen applications on peanut, in field conditions

    Antonio Roberto Giardini

    1985-01-01

    Full Text Available Existe, nas nossas condições, uma população autóctone de Rhizobium capaz de nodular o amendoim (Arachis hypogaea L., mas pouco se sabe da contribuição do nitrogênio fixado para esta planta. Foram conduzidos dois ensaios no campo, em solo de baixa fertilidade, um no período "da seca" e outro no "das águas", comparando o crescimento e a produção de plantas de amendoim inoculado com Rhizobium selecionado, com o de plantas noduladas pela população autóctone, adubadas ou não com nitrogênio. A nodulação das plantas inoculadas foi semelhante à observada nos tratamentos não inoculados, com ou sem nitrogênio. Na fase final do ciclo das plantas, houve maior acúmulo e maior taxa de absorção diária de nitrogênio nos tratamentos inoculados ou com adubação nitrogenada, do que no controle sem inoculação e sem nitrogênio. No ensaio da seca, não houve aumento de produção devido à adubação nitrogenada, ou à inoculação. No ensaio das águas, houve resposta à aplicação de nitrogênio no plantio. Os resultados de produção não foram coerentes com os da marcha de absorção de N. A produção de ensaio das águas foi equivalente a 3.400 kg/ha para o tratamento sem nitrogênio e sem inoculação.Two field experiments were carried out with peanut in the same area on a limed and fertilized "cerrado soil" (originally acidic and low fertility. The first experiment was carried out in the autumn/winter (dry season, and the second one in the subsequent spring/summer (wet season, in Campinas, State of São Paulo, Brazil. Plant development and production of inoculated (three Rhizobium strains and nitrogen fertilized treatments (at planting 25 and 45 days after planting were compared with non-inoculated and non-N-fertilized control. Nodulation of inoculated plants was similar to those of non-inoculated, with or without nitrogen. Greater accumulations, and rates for average daily uptake of nitrogen were observed for inoculated as well as for nitrogen fertilized plants, as compared to the control. In the autumn/winter experiment there was no increase in pod production neither due to nitrogen or to inoculation. In the spring/summer experiment however, the pod production was higher with nitrogen (30kg/N/ha at planting, although higher nitrogen accumulations in plant shoots (sampled 84 days after planting were observed treatments with two of the three inoculated strains.

  7. Rhizobium lemnae sp. nov., a bacterial endophyte of Lemna aequinoctialis.

    Kittiwongwattana, Chokchai; Thawai, Chitti

    2014-07-01

    Bacterial strain L6-16(T) was isolated from Lemna aequinoctialis. Cells were Gram-stain-negative, rod-shaped and motile with monopolar flagella. The phylogenetic analysis of its nearly complete 16S rRNA gene sequence revealed that strain L6-16(T) was a member of the genus Rhizobium. Its closest relative was Rhizobium tarimense PL-41(T) with a 16S rRNA gene sequence similarity value of 98.3%. Sequence similarity analysis of the housekeeping recA and atpD genes showed low levels of sequence similarity (Rhizobium. Strain L6-16(T) was able to grow between pH 5 and 11 (optimum 7.0) and at temperatures ranging from 20 to 41 °C (optimum 30 °C). It tolerated NaCl up to 1 % (w/v) (optimum 0.5%). C18 : 1?7c and/or C18 :? 1?6c (summed feature 8; 79.5%) were found as predominant cellular fatty acids. The DNA G+C content of strain L6-16(T) was 58.1 mol% (Tm). Based on low levels of DNA-DNA relatedness, strain L6-16(T) was distinct from members of phylogenetically related species including R. tarimense PL-41(T) (38.3 ± 0.8%), Rhizobium rosettiformans W3(T) (6.9 ± 0.4%) and Rhizobium pseudoryzae J3-A127(T) (12.3 ± 0.6 %). Strain L6-16(T) was unable to nodulate the roots of Phaseolus vulgaris, and nodC and nifH genes were not detected. The results obtained from phylogenetic analyses, phenotypic characterization and DNA-DNA hybridization indicated that strain L6-16(T) represents a novel species of the genus Rhizobium, for which the name Rhizobium lemnae sp. nov. is proposed. The type strain is L6-16(T) (?= NBRC 109339(T)?= BCC 55143(T)). PMID:24786354

  8. Genetic diversity of Rhizobium from nodulating beans grown in a variety of Mediterranean climate soils of Chile.

    Baginsky, Cecilia; Brito, Belén; Scherson, Rosita; Pertuzé, Ricardo; Seguel, Oscar; Cañete, Alejandro; Araneda, Cristian; Johnson, Warren E

    2015-04-01

    In spite of potentially being an important source of rhizobial diversity and a key determinant of common bean productivity, there is a paucity of data on Rhizobium genetic variation and species composition in the important bean producing area of Chile and only one species has been documented (Rhizobium leguminosarum). In this study, 240 Rhizobium isolates from Torcaza bean (Phaseolus vulgaris L.) nodules established in the highest bean producing area in Chile (33°34'S-70°38'W and 37°36'S-71°47'W) were characterized by PCR-RFLP markers for nodC gene, revealing eight banding patterns with the polymorphic enzyme Hinf I. The locality of San Agustín de Aurora in Central Chile (35°32'S-71°29'W) had the highest level of diversity. Isolates were classified by species using PCR-RFLP markers for 16S rDNA gene and were confirmed by sequencing an internal fragment of the 16S rDNA gene. The results confirmed the presence of R. leguminosarum and three other species of rhizobia nodulating beans in South Central Chile (R. etli, R. tropici and R. leucaenae). R. tropici and R. leucaenae showed the least genetic variation and were most commonly identified in acid soils, while R. etli was the most common species in slightly acidic to moderately alkaline soils, with higher levels of organic matter content. R. leguminosarum was identified in almost all soils, was the most genetically diverse, and was the most common, being documented in soils with pH that ranged between 5.3 and 8.2, and with organic matter content between 2.1 and 4 %. PMID:25533847

  9. [A structural assessment of the role of the cell surface carbohydrates of Rhizobium in the Rhizobium/legume symbiosis]. Progress report, June 1989--June 1991

    Hollingsworth, R.I.

    1991-12-31

    Research continued on the study of cell surface carbohydrates of Rhizobium. Objectives include: To characterize, at a structural level, the differences between the lipopolysaccharides of a representative number of strains from different Rhizobium species to determine which features of LPS structure are species-specific and might, therefore, be determinants of host specificity. Determine the effect(s) of nod gene induction on the structure of Rhizobium lipopolysaccharides and determine whether synthesis of a modified LPS molecule or a new surface glycoconjugate is initiated by nod gene induction. Develop a non-chemical means for rapidly screening large numbers of bacterial strains in order to determine which glycoconjugate structural features are conserved between strains of the same species. Provide the necessary structural information which, when coupled with developments in the rapidly expanding field of Rhizobium genetics, should lead to a clear understanding of the role of Rhizobium surface glycoconjugates in host/symbiont interactions. Progress is discussed.

  10. Nickel availability and hupSL activation by heterologous regulators limit symbiotic expression of the Rhizobium leguminosarum bv. viciae hydrogenase system in Hup(-) rhizobia.

    Brito, B; Monza, J; Imperial, J; Ruiz-Argüeso, T; Palacios, J M

    2000-03-01

    A limited number of Rhizobium and Bradyrhizobium strains possess a hydrogen uptake (Hup) system that recycles the hydrogen released from the nitrogen fixation process in legume nodules. To extend this ability to rhizobia that nodulate agronomically important crops, we investigated factors that affect the expression of a cosmid-borne Hup system from Rhizobium leguminosarum bv. viciae UPM791 in R. leguminosarum bv. viciae, Rhizobium etli, Mesorhizobium loti, and Sinorhizobium meliloti Hup(-) strains. After cosmid pAL618 carrying the entire hup system of strain UPM791 was introduced, all recipient strains acquired the ability to oxidize H(2) in symbioses with their hosts, although the levels of hydrogenase activity were found to be strain and species dependent. The levels of hydrogenase activity were correlated with the levels of nickel-dependent processing of the hydrogenase structural polypeptides and with transcription of structural genes. Expression of the NifA-dependent hupSL promoter varied depending on the genetic background, while the hyp operon, which is controlled by the FnrN transcriptional regulator, was expressed at similar levels in all recipient strains. With the exception of the R. etli-bean symbiosis, the availability of nickel to bacteroids strongly affected hydrogenase processing and activity in the systems tested. Our results indicate that efficient transcriptional activation by heterologous regulators and processing of the hydrogenase as a function of the availability of nickel to the bacteroid are relevant factors that affect hydrogenase expression in heterologous rhizobia. PMID:10698755

  11. Nickel Availability and hupSL Activation by Heterologous Regulators Limit Symbiotic Expression of the Rhizobium leguminosarum bv. Viciae Hydrogenase System in Hup− Rhizobia

    Brito, Belén; Monza, Jorge; Imperial, Juan; Ruiz-Argüeso, Tomás; Palacios, Jose Manuel

    2000-01-01

    A limited number of Rhizobium and Bradyrhizobium strains possess a hydrogen uptake (Hup) system that recycles the hydrogen released from the nitrogen fixation process in legume nodules. To extend this ability to rhizobia that nodulate agronomically important crops, we investigated factors that affect the expression of a cosmid-borne Hup system from Rhizobium leguminosarum bv. viciae UPM791 in R. leguminosarum bv. viciae, Rhizobium etli, Mesorhizobium loti, and Sinorhizobium meliloti Hup− strains. After cosmid pAL618 carrying the entire hup system of strain UPM791 was introduced, all recipient strains acquired the ability to oxidize H2 in symbioses with their hosts, although the levels of hydrogenase activity were found to be strain and species dependent. The levels of hydrogenase activity were correlated with the levels of nickel-dependent processing of the hydrogenase structural polypeptides and with transcription of structural genes. Expression of the NifA-dependent hupSL promoter varied depending on the genetic background, while the hyp operon, which is controlled by the FnrN transcriptional regulator, was expressed at similar levels in all recipient strains. With the exception of the R. etli-bean symbiosis, the availability of nickel to bacteroids strongly affected hydrogenase processing and activity in the systems tested. Our results indicate that efficient transcriptional activation by heterologous regulators and processing of the hydrogenase as a function of the availability of nickel to the bacteroid are relevant factors that affect hydrogenase expression in heterologous rhizobia. PMID:10698755

  12. The effect of exogenous rhizobial lipopolysaccharide on symbiosis of Rhizobium leguminosarum bv. trifolii with red clover

    Maria Głowacka

    2014-02-01

    Full Text Available The effectivity of symbiosis of Rhizobium leguminosarum bv. trifolii with red clover in the presence of exogenous lipopolysaccharide (LPS preparation was measured as a yield of green mass of infected plants. The addition of complete LPS that had been obtained from homological Rhizobium strains influenced significantly the growth of plants. In the presence of defective LPS of Rhizobium mutant the effectivity of symbiosis did not change.

  13. The Effect of Rhizobium spp. Inoculation on Seed Quality of Bean in Turkey

    Cigdem KuCuk

    2008-01-01

    Full Text Available Rhizobium spp. (local isolate was used to inoculate three bean (Phaseolus vulgaris L. varieties; Akman 98, Goynuk 98 and Sehirali 90, in a factorial field experiment. The objective of the experiment was to study effect of inoculation on seed yield, protein range, seed weight, non-soaker capacity and hydration index. Rhizobium spp. inoculation and nitrogen fertilizer significantly increased characters tested. This study revealed that inoculation with Rhizobium spp. improved seed quality.

  14. Isolation and characterization of the constitutive acyl carrier protein from Rhizobium meliloti.

    PLATT, M. W.; Miller, K.J.; Lane, W. S.; Kennedy, E P

    1990-01-01

    Rhizobium species produce an inducible acyl carrier protein (ACP), encoded by the nodF gene, that somehow functions in an exchange of cell signals between bacteria and specific plant hosts, leading to nodulation of plant roots and symbiotic nitrogen fixation, as well as a constitutive ACP needed for the synthesis of essential cell lipids. The periplasmic cyclic glucans of Rhizobium spp. are also involved in specific rhizobium-plant interaction. These glucans are strongly similar to the peripl...

  15. Populasi Bakteri Rhizobium di Tanah pada beberapa Tanaman dari Pulau Buton, Kabupaten Muna, Propinsi Sulawesi Tenggara

    Sri Purwaningsih

    2009-01-01

    The research was conducted in order to know population of Rhizobium bacteria in the soil at several plant from Buton island, Muna regency, Southeast Sulawesi. The purpose of the study was to get the population data and pure cultures of Rhizobium bacteria. Rhizobium bacteria were isolated from 13 sample from rhizosphere of fruit plant, 14 sample soil from rhizosphere of yield plant, 5 sample soil from rhizosphere of horticulture plant, and 8 samples soil was from forest plant. Isolation was c...

  16. The effect of exogenous rhizobial lipopolysaccharide on symbiosis of Rhizobium leguminosarum bv. trifolii with red clover

    Maria Głowacka; Agnieszka Stępień; Sylwia Szyprowska

    2014-01-01

    The effectivity of symbiosis of Rhizobium leguminosarum bv. trifolii with red clover in the presence of exogenous lipopolysaccharide (LPS) preparation was measured as a yield of green mass of infected plants. The addition of complete LPS that had been obtained from homological Rhizobium strains influenced significantly the growth of plants. In the presence of defective LPS of Rhizobium mutant the effectivity of symbiosis did not change.

  17. Interaction of Azospirillum and Rhizobium Strains Leading to Inhibition of Nodulation

    Plazinski, Jacek; Rolfe, Barry G.

    1985-01-01

    Rhizobium-Azospirillum interactions during establishment of Rhizobium-clover symbiosis were studied. When mixed cultures of Azospirillum and Rhizobium trifolii strains were simultaneously inoculated onto clover plants, no nodulation by R. trifolii was observed. R. trifolii ANU1030, which nodulated clover plants without attacking root hairs, i.e., does not cause root hair curling (Hac−), did not show inhibition of nodulation when inoculated together with Azospirillum strains. Isolation of bact...

  18. PENGARUH pH MEDIA PERTUMBUHAN TERHADAP KETAHANAN DARI Rhizobium sp. PADA TANAH YANG BERSIFAT ASAM

    Ni Made Widyasari; Retno Kawuri; I Ketut Muksin

    2015-01-01

    Telah dilakukan penelitian yang bertujuan mengetahui ketahanan Rhizobium sp. yang ditumbuhkan pada pH media pertumbuhan 7,0 dan 5,8 serta mengetahui kemampuan hidup Rhizobium sp. pada media tanah asam dengan pH 5,0 dan respon inokulum Rhizobium sp. pada tanaman kedelai secara in vivo. ATR (Acid Tolerance Responce) didapatkan dengan cara menumbuhkan Rhizobium sp. dengan pH media pertumbuhan 7,0 dan ditambahkan dengan media YMB (Yeast Extract Mannitol Broth) dengan pH 5,8 dan pH 7,0, diinkubasi...

  19. Rhizobium Promotes Non-Legumes Growth and Quality in Several Production Steps: Towards a Biofertilization of Edible Raw Vegetables Healthy for Humans

    García-Fraile, Paula; Carro, Lorena; Robledo, Marta; Ramírez-Bahena, M. H.; Flores-Félix, José-David; Fernández, María Teresa; Mateos, P F; Rivas, R.; Igual, José Mariano; Martínez-Molina, E.; Peix, A.; Velázquez, E.

    2012-01-01

    The biofertilization of crops with plant-growth-promoting microorganisms is currently considered as a healthy alternative to chemical fertilization. However, only microorganisms safe for humans can be used as biofertilizers, particularly in vegetables that are raw consumed, in order to avoid sanitary problems derived from the presence of pathogenic bacteria in the final products. In the present work we showed that Rhizobium strains colonize the roots of tomato and pepper plants promoting thei...

  20. Synergy between Rhizobium phaseoli and Acidithiobacillus ferrooxidans in the Bioleaching Process of Copper.

    Zheng, Xuecheng; Li, Dongwei

    2016-01-01

    This study investigates the synergy of Rhizobium phaseoli and Acidithiobacillus ferrooxidans in the bioleaching process of copper. The results showed that additional R. phaseoli could increase leaching rate and cell number of A. ferrooxidans. When the initial cell number ratio between A. ferrooxidans and R. phaseoli was 2 : 1, A. ferrooxidans attained the highest final cell number of approximately 2 × 10(8) cells/mL and the highest copper leaching rate of 29%, which is 7% higher than that in the group with A. ferrooxidans only. R. phaseoli may use metabolized polysaccharides from A. ferrooxidans, and organic acids could chelate or precipitate harmful heavy metals to reduce their damage on A. ferrooxidans and promote its growth. Organic acids could also damage the mineral lattice to increase the leaching effect. PMID:26942203

  1. Impact of heavy metals on an arctic rhizobium

    Appanna, V.D. (Laurentian Univ., Sudbury, Ontario (Canada))

    1991-03-01

    Bacteria belonging to the genus Rhizobium, when residing in the root nodules of leguminous plants, fix nitrogen and thus contribute very significantly to the global nitrogen and thus contribute very significantly to the global nitrogen budget. Although there is paucity of data concerning the effects of metal pollutants on these agronomically important organisms, their negative impact on the nitrogen fixing ability of these microbes is evident. As rhizobia from root nodules of arctic legumes have been demonstrated to contribute significantly to the ecological balance in this region, the impact of some metals, found in elevated amounts in acidic surroundings on this unique Rhizobium has been assessed. In this paper the ability of the microbe to tolerate abnormal levels of manganese and aluminum is reported and the effectiveness of iron in reversing cadmium toxicity is also discussed.

  2. [The Rhizobium-Prosopis symbiosis in the Argentinian Chaco Arido].

    Abril, A; González, C

    1994-01-01

    Low productivity soils can be improved by incorporation of adapted legumes species able to increase the nitrogen fixation when associated to Rhizobium strains. Two fast-growing Rhizobium strains were isolated from nodules of Prosopis alba. Infectivity and effectivity of the strains were assessed under controlled conditions, measuring the following parameters: nodule number, dry weight, nitrogen percentage and fixed nitrogen. P. flexuosa strains showed high infective capacity (144 nodules/plant) but low effectivity (21.4 mg fixed nitrogen in 75 days). Although nodule number in P. alba was lower (23 nodules/plant) nitrogen fixation was higher (119.5 mg fixed nitrogen in 75 days) as compared with P. flexuosa. The isolated strains might be used as nitrogen donors in aride soils; they might be helpful to forestation of these ecosystems. PMID:7938496

  3. Isolation of a Rhizobium galegae strain-specific DNA probe.

    Tas, E; Kaijalainen, S; Saano, A; Lindström, K

    1994-07-01

    We have isolated a strain-specific DNA probe from the strain Rhizobium galegae HAMBI 1174 by a subtraction hybridization procedure followed by PCR amplification and DNA cloning. The specificity of the 342-bp DNA probe (P3) was tested in dot blot or Southern blot hybridizations against total genomic DNA of 41 bacterial strains (21 of them belong to R. galegae, 15 to other Rhizobium species and five to other bacterial species). Only the samples from four R. galegae strains, which are different isolates but identical to the strain HAMBI 1174, hybridized with the probe. The P3 probe was sequenced and PCR primers were designed based on its sequence. PCR amplification from purified total genomic DNA of 52 strains and subsequent hybridization with the P3 probe proved that the primers are strain specific. PMID:7921351

  4. Use of Two-Dimensional Polyacrylamide Electrophoresis to Demonstrate that Putative Rhizobium Cross-Inoculation Mutants Actually Are Contaminants

    Leps, Walter T.; Roberts, G P; Brill, Winston J.

    1980-01-01

    Two-dimensional polyacrylamide electrophoresis was used to determine that mutants of Rhizobium trifolii DT6, claimed to be capable of effectively nodulating soybeans, were actually Rhizobium japonicum 110 contaminants isolated from the parent DT6 culture.

  5. CSTB - Priorité scientifique et technique "Maîtrise des Risques" : bilan 2010-2013, rapport final

    Vallerent, S.; Blanchard, E.; Delpech, P; Demouge, F.; FLORENCE, C; PIMIENTA, P.; Salagnac, J. L.; Carlotti, P.

    2014-01-01

    La priorité scientifique et technique "Maîtrise des Risques" du programme de recherche 2010-2013 du CSTB avait pour ambition de contribuer à éviter les victimes en protégeant les personnes présentes dans le bâti, de limiter les dommages économiques en protégeant les biens et d'assurer la résilience tant technique qu'humaine. Les travaux portaient sur les risques naturels et anthropiques (incendie, vent, séisme, canicule...) et étaient organisés en quatre projets de recherche. Ce rapport prése...

  6. Diversity of Rhizobium leguminosarum from Pea Fields in Washington State

    Rita Abi-Ghanem; Jeffrey L. Smith; Vandemark, George J.

    2013-01-01

    Rhizobia-mediated biological nitrogen (N) fixation in legumes contributes to yield potential in these crops and also provides residual fertilizer to subsequent cereals. Our objectives were to collect isolates of Rhizobium leguminosarum from several pea fields in Washington, examine genetic diversity among these isolates and several commercial isolates of R. leguminosarum, and compare genetically distinct isolates for their ability to fix N in a range of pea hosts. Seventy-nine isolates were c...

  7. Developmental fate of Rhizobium meliloti bacteroids in alfalfa nodules.

    Paau, A S; Bloch, C B; Brill, W J

    1980-01-01

    Nitrogen-fixing bacteroids are degraded during nodule senescence. This is in contrast to recent implications that viable bacteroids can be released into soil from legume nodules. Rhizobia originating from persistent infection threads in senescing nodule plant cells seem to be the source of viable cells required for perpetuation of the Rhizobium spp. population in the soil. Our conclusions were derived from electron microscopic examination of stages of development and senescence of alfalfa roo...

  8. Bacteriochlorophyll and Photosynthetic Reaction Centers in Rhizobium Strain BTAi 1

    Evans, William R.; Fleischman, Darrell E.; Calvert, Harry E.; Pyati, Padma V.; Alter, Gerald M.; Rao, N. S. Subba

    1990-01-01

    Rhizobium strain BTAi 1, which nodulates both stems and roots of Aeschynomene indica L., formed bacteriochlorophyll and photosynthetic reaction centers resembling those of purple photosynthetic bacteria when grown aerobically ex planta under a light-dark cycle. Bacteriochlorophyll formation was not observed under continuous dark or light growth conditions. The amount of pigment formed was similar to that previously found in aerobic photosynthetic bacteria. Stem nodules appear to fix nitrogen ...

  9. Fine Structure of Succinate-Swollen Rhizobium trifolii 0403

    Urban, James E.; Bechtel, Donald B.

    1984-01-01

    Transmission electron micrographs of glutaraldehyde- OsO4-fixed Rhizobium trifolii 0403 before and after cells were treated with 16.6 mM succinate showed that treated cells increased in mass by increasing cytoplasmic volume. The morphology of succinate-treated cells was identical to that of bacteroids, and the appearances of the envelope and periplasmic space were similar. The primary difference was in inclusion number and type.

  10. Molecular markers to study competition and diversity of Rhizobium.

    Sessitsch, A.

    1997-01-01

    The research described in this thesis was directed to the development of molecular identification and detection techniques for studying the ecology of Rhizobium, a nitrogen- fixing bacterium of agricultural importance. Competition of inoculant strains with indigenous microbes is a serious problem in agricultural practice and was therefore addressed in this work using the developed tools. Furthermore, various molecular techniques have been applied to analyse rhizobial populations nodulating co...

  11. Method for Testing Degree of Infectivity of Rhizobium meliloti Strains

    Olivares, José; Casadesús, Josep; Bedmar, Eulogio J.

    1980-01-01

    The infectiveness of different strains of Rhizobium meliloti was tested with a technique that uses the addition of tetracycline to the root medium. To stop the infection, the antibiotic was added some time after the inoculation of Medicago sativa plants. A coefficient of infectivity for each strain was calculated according to the number of nodules that appeared with and without the addition of the antibiotic. This method seems useful in infectivity studies and is simpler and easier to perform...

  12. Growth of Rhizobium japonicum Strains at Temperatures Above 27°C †

    Munévar, Fernando; Wollum, Arthur G.

    1981-01-01

    A study was conducted to examine the growth responses of different Rhizobium japonicum strains to increasing temperatures, determine the degree of variability among strains in those responses, and identify temperature-related growth characteristics that could be used to select temperature-tolerant strains. Each of 42 strains was grown in liquid culture for 96 h at 19 incubation temperatures ranging from 27.4 to 54.1°C in a temperature gradient apparatus. Growth was estimated by measuring the ...

  13. Recombinant Rhizobium meliloti strains with extra biotin synthesis capability.

    Streit, W. R.; Phillips, D. A.

    1996-01-01

    The growth of Rhizobium meliloti 1021 in an experimental alfalfa (Medicago sativa L.) rhizosphere was stimulated by adding nanomolar amounts of biotin. To overcome this biotin limitation, R. meliloti strains were constructed by conjugating the Escherichia coli biotin synthesis operon into biotin auxotroph R. meliloti 1021-B3. Transconjugant strains Rm1021-WS10 and Rm1021-WS11 grew faster in vitro and achieved a higher cell density than did R. meliloti 1021 and overproduced biotin on a defined...

  14. Complementary Methods for the Differentiation of Rhizobium meliloti Isolates †

    Fuquay, Janice I.; Bottomley, Peter J.; Jenkins, Michael B.

    1984-01-01

    Because of the scarcity of literature on the successful use of serological methods for differentiation of Rhizobium meliloti isolates, the objectives of this study were to provide a rationale for selecting isolates to which antisera could be raised and to appraise the suitability of published methods of preparing R. meliloti antigens for the serological identification of field isolates. We used one-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis to develop protein profil...

  15. Genetic transformation of Rhizobium leguminosarum by plasmid DNA.

    Bullerjahn, G S; Benzinger, R H

    1982-01-01

    We demonstrated the genetic transformation of Rhizobium leguminosarum by R68.45 plasmid DNA by freezing and thawing cell suspensions in the presence of R68.45 plasmid DNA and 20 mM MgCl2. Clones resistant to kanamycin and tetracycline were recovered at a frequency of 10(-8) per recipient cell. No colonies that were doubly drug resistant were recovered in parallel control experiments.

  16. Protozoa and the decline of Rhizobium populations added to soil.

    Danso, S K; Keya, S O; Alexander, M

    1975-06-01

    A fall in Rhizobium abundance occurred in nonsterile soil inoculated with large numbers of the root-nodule bacteria, but many of the rhizobia still survived. No such decline was evident in sterile soil. Protozoa feeding on these bacteria were isolated from soil and other environments. As the abundance of Rhizobium meliloti and a cowpea Rhizobium strain in soil decreased, the protozoan density increased. The inability of the predators to eliminate their prey from soil was not the result of the presence of organisms feeding on the protozoa because many rhizobia survived in sterile soil inoculated with the prey and cultures of individual protozoa, nor was it the result of the rapid multiplication of the bacteria to replace those consumed because survivors were still numerous in essentially organic matter free soil in which the bacteria did not grow appreciably. The lack of elimination also was not associated with a protective effect of soil particles because survivors were still abundant in solutions inoculated with protozoa and bacteria. It is suggested that the size of the prey population diminishes until a density is attained at which the energy used by the predator in hunting for the survivors equals that obtained from the feeding. PMID:807307

  17. Rhizobium rosettiformans sp. nov., isolated from a hexachlorocyclohexane dump site, and reclassification of Blastobacter aggregatus Hirsch and Muller 1986 as Rhizobium aggregatum comb. nov.

    Kaur, Jaspreet; Verma, Mansi; Lal, Rup

    2011-05-01

    A Gram-negative, rod-shaped, motile, aerobic bacterial strain, W3(T), was isolated from hexachlorocyclohexane (HCH)-contaminated groundwater from Lucknow, India, and its taxonomic position was determined using a polyphasic approach. Strain W3(T) shared highest 16S rRNA gene sequence similarity of 97.8 % with Rhizobium selenitireducens B1(T), followed by Rhizobium daejeonense L61(T) (97.7 %), Rhizobium radiobacter ATCC 19358(T) (97.5 %) and Blastobacter aggregatus IFAM 1003(T) (97.2 %). Strain W3(T) formed a monophyletic clade with Blastobacter aggregatus IFAM 1003(T) (?=?DSM 1111(T)) in the cluster of species of the genus Rhizobium. Phylogenetic analyses of strain W3(T) using atpD and recA gene sequences confirmed the phylogenetic arrangements obtained by using 16S rRNA gene sequences. Hence, the taxonomic characterization of B. aggregatus DSM 1111(T) was also undertaken. Strains W3(T) and B. aggregatus DSM 1111(T) contained summed feature 8 (18 : 1?7c and/or 18 : 1?6c; 65.4 and 70.8 %, respectively) as the major fatty acid, characteristic of the genus Rhizobium. DNA-DNA relatedness of strain W3(T) with Rhizobium selenitireducens LMG 24075(T), Rhizobium daejeonense DSM 17795(T), Rhizobium radiobacter DSM 30147(T) and B. aggregatus DSM 1111(T) was 42, 34, 30 and 34 %, respectively. The DNA G+C contents of strain W3(T) and B. aggregatus DSM 1111(T) were 62.3 and 62.7 mol%, respectively. A nifH gene encoding dinitrogenase reductase was detected in strain W3(T) but not in B. aggregatus DSM 1111(T). Based on the results obtained by phylogenetic and chemotaxonomic analyses, phenotypic characterization and DNA-DNA hybridization, it is concluded that strain W3(T) represents a novel species of the genus Rhizobium, for which the name Rhizobium rosettiformans sp. nov. is proposed (type strain W3(T) ?=?CCM 7583(T) ?=?MTCC 9454(T)). It is also proposed that Blastobacter aggregatus Hirsch and Müller 1986 be transferred to the genus Rhizobium as Rhizobium aggregatum comb. nov. (type strain IFAM 1003(T) ?=?DSM 1111(T) ?=?ATCC 43293(T)). PMID:20584817

  18. Rhizobium ipomoeae sp. nov., isolated from a water convolvulus field.

    Sheu, Shih-Yi; Chen, Zih-Han; Young, Chiu-Chung; Chen, Wen-Ming

    2016-04-01

    A bacterial strain, designated shin9-1T, was isolated from a water sample taken from a water convolvulus field in Taiwan and characterized using a polyphasic taxonomical approach. Cells of strain shin9-1T were aerobic, Gram-stain-negative, rod-shaped and surrounded by a thick capsule and formed cream-coloured colonies. Growth occurred at 10-45 °C (optimum, 30 °C), with 0-3.0 % NaCl (optimum, 0.5 %) and at pH 7.0-9.0 (optimum, pH 7.0). Strain shin9-1T did not form nodules on a legume plant, Macroptilium atropurpureum, and the nodulation genes nodA, nodC and the nitrogenase reductase gene nifH were not detected by PCR. Phylogenetic analyses based on 16S rRNA and three housekeeping gene sequences (recA, atpD and rpoB) showed that strain shin9-1T belonged to the genus Rhizobium. Strain shin9-1T had the highest level of 16S rRNA gene sequence similarity with respect to Rhizobium daejeonense L61T (97.6 %). The major fatty acid of strain shin9-1T was C18 : 1ω7c. The polar lipid profile consisted of phosphatidylethanolamine, phosphatidylglycerol, phosphatidylcholine, diphosphatidylglycerol, phosphatidylmonomethylethanolamine and several uncharacterized lipids. The DNA G+C content was 58.3 mol%. The DNA-DNA relatedness of strain shin9-1T with respect to recognized species of the genus Rhizobium was less than 70 %. Phenotypic characteristics of the novel strain also differed from those of the most closely related species of the genus Rhizobium. On the basis of the phylogenetic inference and phenotypic data, strain shin9-1T should be classified as a representative of a novel species, for which the name Rhizobium ipomoeae sp. nov. is proposed. The type strain is shin9-1T ( = LMG 27163T = KCTC 32148T). PMID:26739022

  19. In Rhizobium japonicum the nitrogenase genes nifH and nifDK are separated.

    Kaluza, K.; Fuhrmann, M.; Hahn, M.; Regensburger, B; Hennecke, H

    1983-01-01

    In contrast to Klebsiella pneumoniae or fast-growing Rhizobium species, such as R. meliloti, where the nitrogenase structural genes are clustered in one operon (nifHDK), in slow-growing Rhizobium japonicum 110, nifH and nifDK are on separate operons.

  20. Mobilization of a Sym plasmid from a fast-growing cowpea Rhizobium strain.

    Morrison, N.A.; Cen, Y H; Chen, H.C.; Plazinski, J; Ridge, R; Rolfe, B G

    1984-01-01

    A large Sym plasmid from a fast-growing cowpea Rhizobium species was made mobilizable by cointegration with plasmid pSUP1011, which carries the oriT region of RP4. This mobilizable Sym plasmid was transferred to a number of Rhizobium strains, in which nodulation and nitrogen fixation functions for symbiosis with plants of the cowpea group were expressed.

  1. Contribución al estudio de los plásmidos de Rhizobium

    Cubo Sánchez, María Teresa

    1988-01-01

    En este trabajo, hemos estudiado la transferencia y expresión del plásmido simbiótico PJB5JI de Rhizobium leguminosarum biovar viceae en diversas estirpes de Rhizobium sp. y Bradyrhizobium sp. que nodulan en Cicer arietinum y en Cajanus cajan. De los resu

  2. Expression of symbiotic genes of Rhizobium japonicum USDA 191 in other rhizobia.

    Appelbaum, E R; McLoughlin, T J; O'Connell, M.; Chartrain, N

    1985-01-01

    A 200-megadalton plasmid was mobilized from Rhizobium japonicum USDA 191 to other Rhizobium strains either that cannot nodulate soybeans or that form Fix- nodules on certain cultivars. The symbiotic properties of the transconjugants indicate that both soybean specificity for nodulation and cultivar specificity for nitrogen fixation are plasmid encoded.

  3. Effects of nano-ZnO on the agronomically relevant Rhizobium-legume symbiosis

    The impact of nano-ZnO (nZnO) on Rhizobium-legume symbiosis was studied with garden pea and its compatible bacterial partner Rhizobium leguminosarum bv. viciae 3841. Exposure of peas to nZnO had no impact on germination, but significantly affected root length. Chronic exposure of plant to nZnO impac...

  4. Danish Rhizobium leguminosarum strains nodulating ‘Afghanistan’ pea (Pisum sativum)

    Jensen, Erik Steen; Sørensen, Lasse Holst; Engvild, Kjeld Christensen

    1986-01-01

    A wild pea (Pisum sativum L.) native to Afghanistan normally known to be resisant to nodulation with European strains of Rhizobium leguminosarum was nodulated early and effectively in field soil in Denmark. Isolates from nodules formed effective nodules abundantly on 'Afghanistan' on reinfection...... pattern with Rhizobium leguminosarum strains isolated from a modern pea variety cultivated in the same field....

  5. Rhizobium selenireducens sp. nov.: A selenite reducing a-Proteobacteria isolated from a bioreactor

    A Gram-negative, non-pigmented bacterium designated strain B1 was isolated from a laboratory bioreactor that reduced selenate to elemental red selenium (Se0). 16S rRNA gene sequence alignment identified the isolate as a Rhizobium sp. belonging to the Rhizobium clade that includes R. daejeonense, R....

  6. Effects of nano-TiO2 on the agronomically-relevant Rhizobium-legume symbiosis

    The impact of nano-TiO2 on Rhizobium-legume symbiosis was studied using garden peas and the compatible bacterial partner Rhizobium leguminosarum bv. viciae 3841. Exposure to nano-TiO2 did not affect the germination of peas grown aseptically, nor did it impact the gross root structure. However, nano-...

  7. Preliminary data on some correlations of Rhizobium and radio-stimulation seed treatments

    The seeds of peas, beans, soy-beans and lucerne were treated with 60Co-irradiation (4-10 Gray). The size of the roots and the quantity of seed-crop were measured. Irradiation by itself had no significant effect. Treatment with Rhizobium bacteria and with Rhizobium plus irradiation had considerable positive effects. (L.E.)

  8. 78 FR 22298 - United States v. Apple, Inc., et al.; Public Comments and Response on Proposed Final Judgment

    2013-04-15

    .... Apple CEO Steve Jobs urged one Publisher Defendant to `` hrow in with Apple and see if we can all make a..., see United States v. Apple, Inc., et al., 77 FR 77094; and summaries of the terms of the...

  9. Evidence of an American Origin for Symbiosis-Related Genes in Rhizobium lusitanum ▿

    Valverde, Angel; Velázquez, Encarna; Cervantes, Emilio; Igual, José M.; van Berkum, Peter

    2011-01-01

    Randomly amplified polymorphic DNA (RAPD) analysis was used to investigate the diversity of 179 bean isolates recovered from six field sites in the Arcos de Valdevez region of northwestern Portugal. The isolates were divided into 6 groups based on the fingerprint patterns that were obtained. Representatives for each group were selected for sequence analysis of 4 chromosomal DNA regions. Five of the groups were placed within Rhizobium lusitanum, and the other group was placed within R. tropici type IIA. Therefore, the collection of Portuguese bean isolates was shown to include the two species R. lusitanum and R. tropici. In plant tests, the strains P1-7, P1-1, P1-2, and P1-16 of R. lusitanum nodulated and formed nitrogen-fixing symbioses both with Phaseolus vulgaris and Leucaena leucocephala. A methyltransferase-encoding nodS gene identical with the R. tropici locus that confers wide host range was detected in the strain P1-7 as well as 24 others identified as R. lusitanum. A methyltransferase-encoding nodS gene also was detected in the remaining isolates of R. lusitanum, but in this case the locus was that identified with the narrow-host-range R. etli. Representatives of isolates with the nodS of R. etli formed effective nitrogen-fixing symbioses with P. vulgaris and did not nodulate L. leucocephala. From sequence data of nodS, the R. lusitanum genes for symbiosis were placed within those of either R. tropici or R. etli. These results would support the suggestion that R. lusitanum was the recipient of the genes for symbiosis with beans from both R. tropici and R. etli. PMID:21705533

  10. Strain identification in Rhizobium by starch gel electrophoresis of isoenzymes

    Engvild, Kjeld Christensen; Nielsen, G.

    1985-01-01

    Sonieated extracts of rhizobia, especiaUy Rhizobium leguminosarum from pea and vetch, were run in horizontal starch gel electrophoresis in the cold. The rhizobia were grown on agar on a slime suppressing substrate of tryptone-yeast extract-CaCl2 with small amounts of mannitol, sorbitol and...... arabinose and other sugars as enzyme inducers. After electrophoresis the gels were separated into several slabs by a gel cutter. Each slab was stained for a particular enzyme. Among numerous enzyme systems tested we found useful variation in esterases (EC 3.1.1.1, EC 3.1.1.2), 3-hydroxybutyrate...

  11. Relations between Rhizobium and radiostimulation treatments of seeds

    In field experiments the effects of irradiation with 60Co isotope the seeds of round seeded peas (Pisum sativum L.), beans (Phaseolus vulgaris L.), soybeans (Glycine max. L./Merr.) and lucerne (Medicago sativa) were investigated. Rhizobium bacteria inoculation was carried out with the inoculator ''Rhizonit''. The green mass yield was determined for lucerne and the grain yield for the other plants. Irradiation induced flowering of peas 4-5 days earlier. The bean yields increased significantly on the influence of 1000 rad irradiation plus Rhizonit inoculation. For soybeans the yield response to Rhizonit proved to be significant. (author)

  12. 75 FR 60820 - United States v. Adobe Systems, Inc., et al.; Proposed Final Judgment and Competitive Impact...

    2010-10-01

    ... Statement, 61 FR 28891, 28894 (W.D.Mo. May 28, 1996). The Court entered an agreed-upon Final Judgment... that case, two movie theater booking agents agreed to refrain from actively soliciting each other's... the merits of the Complaint. VIII. Standard of Review Under the APPA for Proposed Final Judgment...

  13. 75 FR 9929 - United States v. Bemis Company, Inc., et al.; Proposed Final Judgment and Competitive Impact...

    2010-03-04

    ... Final Judgment, filed the same time as the Complaint, requires Bemis to divest the assets of Alcan... acquires the divested assets in order to ensure that customers continue to receive a reliable supply of the... Final Judgment: A. ``Acquirer'' or ``Acquirers'' means the entity or entities to whom defendants...

  14. 78 FR 33437 - United States v. Apple, Inc., et al.; Public Comments and Response on Proposed Final Judgment

    2013-06-04

    ... 25, 2013, see United States v. Apple, Inc., et al., 78 FR 12874; and summaries of the terms of the..., e.g., Original Response to Comments (Docket No. 81; 77 FR 44271); Penguin Response to Comments (Docket No. 201; 78 FR 22298). This Court also articulated the standard of review in its Opinion and...

  15. PENGARUH pH MEDIA PERTUMBUHAN TERHADAP KETAHANAN DARI Rhizobium sp. PADA TANAH YANG BERSIFAT ASAM

    Ni Made Widyasari

    2015-02-01

    Full Text Available Telah dilakukan penelitian yang bertujuan mengetahui ketahanan Rhizobium sp. yang ditumbuhkan pada pH media pertumbuhan 7,0 dan 5,8 serta mengetahui kemampuan hidup Rhizobium sp. pada media tanah asam dengan pH 5,0 dan respon inokulum Rhizobium sp. pada tanaman kedelai secara in vivo. ATR (Acid Tolerance Responce didapatkan dengan cara menumbuhkan Rhizobium sp. dengan pH media pertumbuhan 7,0 dan ditambahkan dengan media YMB (Yeast Extract Mannitol Broth dengan pH 5,8 dan pH 7,0, diinkubasi pada suhu 280C selama 24 jam pada shaker. Penghitungan total mikroba dilakukan setiap 2 jam sekali dengan menggunakan platting method. Uji ketahanan Rhizobium sp. pada tanah asam dengan pH 5,0 secara in vitro dengan cara menghitung total bakteri dengan menggunakan platting method setiap hari selama 28 hari. Uji in vivo dilakukan dirumah kaca dengan menggunakan metoda MPN (Most Probable Number. Hasil penelitian menunjukkan Rhizobium sp. yang dikondisikan pertumbuhannya dengan pH 5,8 lebih resisten dan dapat membentuk ATR dibandingkan dengan Rhizobium sp. yang ditumbuhkan pada pH media 7,0. Pada pH 5,8 setelah 10 jam total bakteri 285 CFU/g sedangkan pada pH 7,0 total bakteri 148 CFU/g. Rhizobium sp. mampu hidup pada tanah asam dengan pH 5,0 dan membentuk ATR pada hari ke 6 dengan total bakteri 137 x 104 CFU/g, tetapi respon inokulum Rhizobium sp. pada tanah dengan pH 5,0 tidak terjadi pembentukan nodul pada tanaman kedelai dikarenakan tanaman kedelai mengalami defisiensi unsur hara.

  16. Primary Bacteremia Caused by Rhizobium radiobacter in Neonate: A Rare Case Report.

    Tiwari, Shreekant; Beriha, Siba Shanker

    2015-10-01

    Rhizobium radiobacter is a gram-negative tumourigenic plant pathogen that rarely causes infections in humans. Rhizobium radiobacter has a strong predilection to cause infection particularly in those patients who have long standing indwelling foreign devices. Herewith we report a rare case of Rhizobium radiobacter bacteremia in a new born baby without other risk factors. The patient was successfully treated with gentamicin and imipenem. To the best of our knowledge this is the first documented case of R. radiobacter from India causing neonatal infection. PMID:26557521

  17. Suicide plasmid vehicles for insertion mutagenesis in Rhizobium meliloti and related bacteria.

    Selvaraj, G; Iyer, V N

    1983-01-01

    We describe the construction and use of a set of plasmid vectors of the transposons Tn1, Tn5, and Tn9 that are suicidal in Rhizobium species and therefore suitable for mutagenesis with these three transposons. The vectors are composed of the p15A replicon which functions in Escherichia coli but not in Rhizobium species and a region encoding the N type of bacterial conjugation system which is very efficient in matings between E. coli and Rhizobium species. The usefulness of the vectors has bee...

  18. Estudio de las propiedades simbióticas de las estirpes de Rhizobium Fredii

    Buendía Clavería, Ana María

    1988-01-01

    En 1982, Keyser y Col. aislaron unas bacterias de crecimiento rápido a partir de nódulos de plantas de soja. Estas nuevas estirpes se han agrupado en la nueva especie Rhizobium fredii. Nosotros hemos estudiado la transferencia y expresión de los plásmidos simbióticos p42d Y pRtr5a en la estirpe USDA 194 de Rhizobium fredii. En segundo lugar, hemos estudiado las propiedades simbióticas de diversas estirpes de Rhizobium fredii en diferentes variedades de soja y en diversas plantas del grupo Cow...

  19. Effet du stress salin en milieu hydroponique sur le trèfle inoculé par le Rhizobium

    Ben Khaled, Laaziza; Gõmez, Asunćion; Honrubia, Mario; Oihabi, Abdallah

    2003-01-01

    L'application d'un stress salin en milieu hydroponique à des plantules de trèfle (Trifolium alexandrinum L.) inoculées par le Rhizobium affecte la nodulation à partir de 2 g $\\cdot$ l$^{-1}$ NaCl alors que la croissance ne l'a été qu'à partir 4 g $\\cdot$ l$^{-1}$. La croissance pondérale de la partie aérienne a été réduite de 20 % à 4 g $\\cdot$ l$^{-1}$ et de 44 % à 6 g $\\cdot$ l$^{-1}$. Le développement du système racinaire a été moins sensible. Cet effet dépressif sur la croissance s'est ac...

  20. Comparison of DNA Polymerase of Rhizobium meliloti and Alfalfa Bacteroids.

    Paau, A; Cowles, J R

    1975-10-01

    DNA dependent-DNA polymerase activity was established and partially purified from extracts of cultured Rhizobium meliloti, F-28, and nodule bacteroids (R. meliloti, F-28) of alfalfa plants (Medicago sativa). Polymerase activity in the partially purified fractions showed characteristic dependence on Mg(2+), DNA, and a full complement of deoxyribonucleoside triphosphates. DNase activity, preference of "activated" double strand DNA, and inhibition by p-chloromercuribenzoate and MnCl(2) were responses common to both systems. The two systems however did exhibit some differences in pH, Mg(2+), and primer optima. Polymerase activity in crude extracts of the cultured bacteria was more stable and had 10- to 18-fold greater specific activity than the bacteroid extracts. Preliminary measurements of specific DNA polymerase activity in crude extracts of cultured Rhizobium japonicum were not significantly higher than that in the crude extracts of soybean nodule bacteroids. A possible correlation between DNA synthesis and the successful establishment of rhizobia-legume symbiosis is discussed. PMID:16659337

  1. A rhizobium leguminosarum mutant defective in symbiotic iron acquisition

    Iron acquisition by symbiotic Rhizobium spp. is essential for nitrogen fixation in the legume root nodule symbiosis. Rhizobium leguminosarum 116, an ineffective mutant strain with a defect in iron acquisition, was isolated after nitrosoguanidine mutagenesis of the effective strain 1062. The pop-1 mutation in strain 116 imparted to it a complex phenotype, characteristic of iron deficiency. Several iron(III)-solubilizing agents, such as citrate, hydroxyquinoline, and dihydroxybenzoate, stimulated growth of 116 on low-iron solid medium; anthranilic acid, the R. leguminosarum siderophore, inhibited low-iron growth of 116. The initial rate of 55Fe uptake by suspensions of iron-starved 116 cells was 10-fold less than that of iron-starved wild-type cells. Electron microscopic observations revealed no morphological abnormalities in the small, white nodules induced by 116. Nodule cortical cells were filled with vesicles containing apparently normal bacteroids. No premature degeneration of bacteroids or of plant cell organelles was evident. The authors mapped pop-1 by R plasmid-mediated conjugation and recombination to the ade-27-rib-2 region of the R. leguminosarum chromosome. No segregation of pop-1 and the symbiotic defect was observed among the recombinants from these crosses. Cosmid pKN1, a pLAFR1 derivative containing a 24-kilobase-pair fragment of R. leguminosarum DNA, conferred on 116 the ability to grow on dipyridyl medium and to fix nitrogen symbiotically

  2. Microgravity effects on the legume/Rhizobium symbiosis

    Urban, James E.

    1997-01-01

    Symbiotic nitrogen fixation is of critical importance to world agriculture and likely will be a critical part of life support systems developed for prolonged missions in space. Bacteroid formation, an essential step in an effective Dutch White Clover/Rhizobium leguminosarum bv trifolii symbiosis, is induced by succinic acid which is produced by the plant and which is bound and incorporated by the bacterium. Aspirin mimics succinate in its role as a bacteroid inducer and measures of aspirin binding mimiced measurements of succinate binding. In normal gravity (1×g), rhizobium bacteria immediately bound relatively high levels of aspirin (or succinate) in a readily reversible manner. Within a few seconds a portion of this initially bound aspirin became irreversibly bound. In the microgravity environment aboard the NASA 930 aircraft, rhizobia did not display the initial reversible binding of succinate, but did display a similar kinetic pattern of irreversible binding, and ultimately bound 32% more succinate (Acta Astronautica 36:129-133, 1995.) In normal gravity succinate treated cells stop dividing and swell to their maximum size (twice the normal cell volume) within a time equivalent to the time required for two normal cell doublings. Swelling in microgravity was tested in FPA and BPM sample holders aboard the space shuttle (USML-1, and STS-54, 57, and 60.) The behavior of cells in the two sample holders was similar, and swelling behavior of cells in microgravity was identical to behavior in normal gravity.

  3. Response of Snap Bean Cultivars to Rhizobium Inoculation under Dryland Agriculture in Ethiopia

    Hussien Mohammed Beshir

    2015-07-01

    Full Text Available High yield in snap bean (Phaseolus vulgaris L. production requires relatively high nitrogen (N inputs. However, little information is available on whether the use of rhizobial inoculants for enhanced biological dinitrogen fixation can provide adequate N to support green pod yield. The objectives of this study were to test the use of rhizobia inoculation as an alternative N source for snap bean production under rain fed conditions, and to identify suitable cultivars and appropriate agro-ecology for high pod yield and N2 fixation in Ethiopia. The study was conducted in 2011 and 2012 during the main rainy season at three locations. The treatments were factorial combinations of three N treatments (0 and 100 kg·N·ha−1, and Rhizobium etli (HB 429 and eight snap bean cultivars. Rhizobial inoculation and applied N increased the total yield of snap bean pod by 18% and 42%, respectively. Cultivar Melkassa 1 was the most suitable for a reduced input production system due to its greatest N2 fixation and high pod yield. The greatest amount of fixed N was found at Debre Zeit location. We concluded that N2 fixation achieved through rhizobial inoculation can support the production of snap bean under rain fed conditions in Ethiopia.

  4. New taxonomic markers for identification of Rhizobium leguminosarum and discrimination between closely related species.

    Janczarek, Monika; Kalita, Micha?; Skorupska, Anna Maria

    2009-03-01

    Rhizobia, producing species-specific exopolysaccharides (EPSs), comprise a very diverse group of soil bacteria that are able to establish nitrogen-fixing symbioses with legumes. Based on the sequences of R. leguminosarum EPS synthesis genes, a sensitive and reliable PCR-based method for identification and subsequent discrimination between Rhizobium species has been developed and tested. For identification of R. leguminosarum, primer sets I-III complementary to sequences of rosR, pssA and pssY genes were proposed. Further sets of primers (IV-VII) were designed for discrimination between R. leguminosarum biovars. The usefulness of the method was examined using a wide range of R. leguminosarum strains isolated from different host plants nodules originating from different regions of Poland. We demonstrate a high discriminating power of primer sets I-III that allow distinguishing R. leguminosarum and two closely related species, R. etli and R. gallicum. This new approach is applicable to identification of R. leguminosarum strains, originating from nodules or soil, where many other closely related bacteria are expected to be present. Based on the nucleotide sequence of rosR and pssA genes, phylogenetic relationships of selected R. leguminosarum isolates were determined. Our results indicate that both rosR and pssA might be useful markers to differentiate and define relationships within a group of R. leguminosarum strains. PMID:19020864

  5. Pré-seleção de estirpes de Rhizobium sp. para amendoim Preliminary selection of peanut Rhizobium sp. strains

    Antonio Roberto Giardini

    1984-01-01

    Full Text Available Um ensaio foi conduzido em casa de vegetação, com solução nutritiva isenta de N, com o objetivo de selecionar estirpes de Rhizobium eficientes fixadoras de N2, quando associadas com amendoim (Arachis hypogaea L. cultivar Tatu. Foram testadas 35 estirpes de Rhizobium sp., isoladas de quinze diferentes espécies de leguminosas tropicais, e incluído um tratamento de inoculação com solo previamente cultivado com amendoim. Das 35 estirpes testadas, doze formaram nódulos e, entre essas, sete foram eficientes fixadoras de nitrogênio. Das doze estirpes que nodularam, sete foram isoladas de leguminosas da tribo Hedysareae (à qual pertence o género Arachis e, destas, apenas quatro foram eficientes fixadoras de nitrogênio. O peso e o número de nódulos não se mostraram como critérios adequados para avaliação da eficiência.An experiment was carried out in Leonard jars, in the greenhouse, with nitrogen-free nutrient solution to test the efficiency of 35 strains of rhizobia isolated from 15 species of tropical legumes. Twelve of the tested strains were capable of nodule formation in peanut. Seven of those strains were isolated from the trible Hedysareae, which includes the genus Arachis. Only four of the rhizobia strains with inducing nodulation were effective. Dry weight and number of nodules were not good criteria for evaluating effectiveness.

  6. 76 FR 21006 - United States and State of New York v. Stericycle, Inc., et al.; Proposed Final Judgment and...

    2011-04-14

    ..., along with associated tangible and intangible assets, must be acceptable to the United States, in its... whereas, the essence of this Final Judgment is the prompt and certain divestiture of the Divestiture Asset... the Divestiture Asset. B. ``Stericycle'' means defendant Stericycle, Inc., a Delaware corporation...

  7. Survival of Rhizobium phaseoli in Coal-Based Legume Inoculants Applied to Seeds †

    Crawford, S. L.; Berryhill, D L

    1983-01-01

    Eight coals used as carriers in legume inoculants promoted the survival of Rhizobium phaseoli on pinto bean seeds. Although peat was more protective, most coal-based inoculants provided >104 viable rhizobia per seed after 4 weeks.

  8. Nitrogen fixing capacity of some soybean cultivars inoculated with different Rhizobium japonicum strains

    The nitrogen-fixing efficiency of different Rhizobium japonicum strains was tested. The strains were inoculated into three soybean cultivars and grain yield, total nitrogen content and nitrogen-fixing capacity were determined. 4 refs, 1 tab

  9. Density Centrifugation Method for Recovering Rhizobium spp. from Soil for Fluorescent-Antibody Studies †

    Wollum, A. G.; Miller, R. H.

    1980-01-01

    A density centrifugation procedure has been developed as a replacement for soil flocculation and clarification steps employed in quantitative fluorescent-antibody studies on Rhizobium in soils. Near-quantitative recovery of added cells of two strains of Rhizobium japonicum and two strains of R. phaseoli was achieved from six soils with various properties. It is proposed that this technique may prove useful in separating other soil microorganisms from soil particles in ecological studies emplo...

  10. The central domain of Rhizobium leguminosarum DctD functions independently to activate transcription.

    Huala, E; Stigter, J; Ausubel, F. M.

    1992-01-01

    Sigma 54-dependent transcriptional activators such as Escherichia coli NtrC, Rhizobium meliloti NifA, and Rhizobium leguminosarum DctD share similar central and carboxy-terminal domains but differ in the structure and function of their amino-terminal domains. We have deleted the amino-terminal and carboxy-terminal domains of R. leguminosarum DctD and have demonstrated that the central domain of DctD, like that of NifA, is transcriptionally competent.

  11. Exopolysaccharide-Deficient Mutants of Rhizobium fredii HH303 Which Are Symbiotically Effective

    Kim, Choong-Hyun; Tully, Raymond E.; Keister, Donald L.

    1989-01-01

    Nineteen Tn5-induced mutants of Rhizobium fredii HH303 defective in acidic exopolysaccharide synthesis were isolated by screening for lack of Calcofluor fluorescence. They were grouped by complementation analysis by using Rhizobium meliloti cosmids carrying exo genes. All of the 19 mutants were symbiotically effective or partially effective, indicating that the major bacterial acidic exopolysaccharide of this strain of R. fredii may not be required for symbiotic development in the soybean.

  12. Possible Involvement of Phage-Like Structures in Antagonism of Cowpea Rhizobia by Rhizobium trifolii

    Joseph, M. V.; Desai, J D; Desai, A J

    1985-01-01

    A reduction in the viability of cowpea rhizobia was observed when Rhizobium trifolii IARI and cowpea Rhizobium strain 3824 were inoculated together in soil. The reduction in number of cowpea rhizobia in soil was found to be associated with the reduction in number of nodules per plant and retardation in plant growth. An antimicrobial substance was isolated from R. trifolii which, on electron microscopic investigation, demonstrated the presence of several phage-like structures.

  13. Interactions of Meloidogyne incognita, Xanthomonas campestris, and Rhizobium sp. in the disease complex of chickpea

    SIDDIQUI, Zaki Anwar; FATIMA, Munavvar; ALAM, Subha

    2013-01-01

    The effects of Meloidogyne incognita, Xanthomonas campestris, and Rhizobium sp., alone or in combination, on the disease complex in chickpea were examined. Individual inoculation with M. incognita and X. campestris caused significant reductions in plant growth, while inoculation with Rhizobium sp. resulted in a significant increase in plant growth. Inoculation with M. incognita and X. campestris together caused a greater reduction in plant growth than the damage caused by each of them alone. ...

  14. Identification and characterization of symbiotic genes on the Rhizobium leguminosarum PRE sym-plasmid.

    Schetgens, T.M.P.

    1986-01-01

    Bacteria of the genera Rhizobium and Bradyrhizobium are unique in their quality to form nitrogen-fixing root nodules in symbiosis with leguminous plants. In fast-growing Rhizobium bacteria the genes involved in host recognition and nodule development ( nod ) and in nitrogen fixation ( nif or fix ) are located on large sym -plasmids (for recent review see e.g. Ausubel, 1984).The aim of the present investigations was to identify symbiotic genes in R.leguminosarum PRE and to study their expressi...

  15. Antimicrobial activities of Rhizobium sp. strains against Pseudomonas savastanoi, the agent responsible for the olive knot disease in Algeria

    Mourad, K.; Fadhila, K.; Chahinez, M.; Merien, R.; Philippe, L. de; Abdelkader, B.

    2009-07-01

    In the present investigation, six Rhizobium strains isolated from Algerian soil were checked for their antimicrobial activity against Pseudomonas savastanoi, the agent responsible for olive knot disease. Rhizobium sp. ORN 24 and ORN 83 were found to produce antimicrobial activities against Pseudomonas savastanoi. The antimicrobial activity produced by Rhizobium sp. ORN24 was precipitable with ammonium sulfate, between 1,000 and 10,000 KDa molecular weight, heat resistant but sensitive to proteases and detergents. These characteristics suggest the bacteriocin nature of the antimicrobial substance produced by Rhizobium sp. ORN24, named rhizobiocin 24. In contrast, the antimicrobial activity produced by Rhizobium sp. ORN83 was not precipitable with ammonium sulfate; it was smaller than 1,000 KDa molecular weight, heat labile, and protease and detergent resistant. These characteristics could indicate the relationship between the antimicrobial substance produced by Rhizobium sp. ORN 83 and the small bacteriocins described in other rhizobia. (Author) 51 refs.

  16. Rhizobium vallis sp. nov., isolated from nodules of three leguminous species.

    Wang, Fang; Wang, En Tao; Wu, Li Juan; Sui, Xin Hua; Li, Ying; Chen, Wen Xin

    2011-11-01

    Four bacterial strains isolated from root nodules of Phaseolus vulgaris, Mimosa pudica and Indigofera spicata plants grown in the Yunnan province of China were identified as a lineage within the genus Rhizobium according to the analysis of 16S rRNA gene sequences, sharing most similarity with Rhizobium lusitanum P1-7(T) (99.1 % sequence similarity) and Rhizobium rhizogenes IAM 13570(T) (99.0 %). These strains also formed a distinctive group from the reference strains for defined species of the genus Rhizobium in a polyphasic approach, including the phylogenetic analyses of the 16S rRNA gene and housekeeping genes (recA, atpD, glnII), DNA-DNA hybridization, BOX-PCR fingerprinting, phenotypic characterization, SDS-PAGE of whole-cell proteins, and cellular fatty acid profiles. All the data obtained in this study suggested that these strains represent a novel species of the genus Rhizobium, for which the name Rhizobium vallis sp. nov. is proposed. The DNA G+C content (mol%) of this species varied between 60.9 and 61.2 (T(m)). The type strain of R. vallis sp. nov. is CCBAU 65647(T) ( = LMG 25295(T) =HAMBI 3073(T)), which has a DNA G+C content of 60.9 mol% and forms effective nodules on Phaseolus vulgaris. PMID:21131504

  17. Uji Asosiasi Bakteri Rhizobium Terseleksi dengan Leguminosa Pakan dalam Kondisi Tercekam Salin

    Eny Fuskhah

    2014-04-01

    Full Text Available (Test of Association Selected Rhizobium Bacteria with Legumes in Salinity Stress ABSTRACT. The research aim was to investigate association selected rhizobium bacteria with legumes in salinity stress. Plant media was salin soil that have EC = 20.45 mmhos/cm which taken from Morosari beach, Sayung, Demak. Rhizobium isolate applied was tolerant to 12.000 ppm of NaCl that equaled to electrical conductivity of 20 mmhos/cm. The research was carried out in green house of Laboratory of Forage Science Diponegoro University Semarang. The design arranged was completely randomized design with factorial design 2 x 4 in 3 repeatations. First factor was kind of legumes, T1 = lamtoro (Leucaena leucocephala; T2 = turi (Sesbania grandiflora. and second factor was kind of rhizobium isolates, I1 = without isolate; I2 = rhizobium that was isolated from lamtoro, I3 = rhizobium that was isolated from turi; I4 = combination isolate from lamtoro and turi. The crop growth was observed up to 10 weeks of age. The parameters were 1 crops heigh; 2 sum of leaf crops; 3 fresh weight production; 4 dry weight production; 5 amount and fresh weigh of effective root nodules. The study showed the growth and production of turi in saline media of EC 20.45 mmhos/cm was higher than lamtoro. Root nodule of turi was formed, but lamtoro was not. Turi was more tolerant than lamtoro at very saline media.

  18. Antimicrobial activities of Rhizobium sp strains against Pseudomonas savastanoi, the agent responsible for the olive knot disease in Algeria

    Kacem, M.; Kazouz, F.; Merabet, C.; Rezki, M.; de Lajudie, Philippe; Bekki, A

    2009-01-01

    In the present investigation, six Rhizobium strains isolated from Algerian soil were checked for their antimicrobial activity against Pseudomonas savastanoi, the agent responsible for olive knot disease. Rhizobium sp. ORN 24 and ORN 83 were found to produce antimicrobial activities against Pseudomonas savastanoi. The antimicrobial activity produced by Rhizobium sp. ORN24 was precipitable with ammonium sulfate, between 1,000 and 10,000 KDa molecular weight, heat resistant but sensitive to prot...

  19. Role of Rhizobium Inoculation in Chickpea (Cicer arietinum L.) Under Water Stress Conditions

    Rahat Parveen; Sadiq, M.; Muzammil Saleem

    1999-01-01

    Two chickpea varieties viz., 90122 and 93081 were subjected to Rhizobium inoculation with BioPower under water stress conditions, imposed by withholding water. Stress reduced all the parameters including yield components and this effect was more pronounced by stress at reproductive stage as compared with vegetative stage. Rhizobium inoculation enhanced yield under both normal and stressed conditions, but its performance was better under normal than under stress. Rhizobium inoculation proved i...

  20. Use of combined inoculum of Azospirillum and Rhizobium in winged bean Psophocarpus tetragonolobus (L) D.C

    Iruthayathas, EE.; Vlassak, K.

    1985-01-01

    The potential of using the free living N -fixing Azospirillum in increasing the nodulation and N2-fixation by Rhizobium in winged bean was analysed. Various strains of winged bean Rhizobium and several strains of Azospirillum were tested in combined inoculations. Substantial increases in nodulation, N2-fixation, shoot dry matter production and N gain due to the mixed inoculation were obtained in one Rhizobium strain namely KUL-BH and most of the Azospirillum strains used. The influence of Rhi...

  1. Carbon Metabolism Enzymes of Rhizobium tropici Cultures and Bacteroids.

    Romanov, V I; Hernández-Lucas, I; Martínez-Romero, E

    1994-07-01

    We determined the activities of selected enzymes involved in carbon metabolism in free-living cells of Rhizobium tropici CFN299 grown in minimal medium with different carbon sources and in bacteroids of the same strain. The set of enzymatic activities in sucrose-grown cells suggests that the pentose phosphate pathway, with the participation of the Entner-Doudoroff pathway, is probably the primary route for sugar catabolism. In glutamate- and malate-grown cells, high activities of the gluconeogenic enzymes (phosphoenolpyruvate carboxykinase, fructose-6-phosphate aldolase, and fructose bisphosphatase) were detected. In bacteroids, isolated in Percoll gradients, the levels of activity for many of the enzymes measured were similar to those of malate-grown cells, except that higher activities of glucokinase, glucose-6-phosphate dehydrogenase, and NAD-dependent phosphogluconate dehydrogenase were detected. Phosphoglucomutase and UDP glucose pyrophosphorylase showed high and constant levels under all growth conditions and in bacteroids. PMID:16349319

  2. Differences between strains of Rhizobium in sensitivity to canavanine

    Four strains of rhizobia that nodulate canavanine-synthesizing legumes and four strains that nodulate noncanavanine-synthesizing legumes were tested for sensitivity to L-canavanine. The effect of canavanine on growth depends upon the strain of Rhizobium tested rather than the canavanine synthesizing capability of the host legume. In both groups of rhizobia, some strains were inhibited in growth by canavanine. Canavanine enhancement of growth was observed in rhizobia that nodulate noncanavanine-synthesizing legumes. Canavanine was found to enhance the incorporation of 3H-uridine and 3H-L-leucine into trichloroacetic acid insoluble fractions of starved cells of two strains of rhizobia tested. This demonstrated that under certain conditions, some rhizobia can detoxify canavanine and utilize it in synthetic processes

  3. The impact of the EU ETS on electricity prices. Final report to DG Environment of the European Commission

    On February 2, 2009, a revised edition of the report has been released, including some adjustments and editorial corrections particularly in Section 2.2 and Appendix A. The present study analyses the impact of the EU Emissions Trading Scheme (ETS) on electricity prices, in particular on wholesale power markets across the EU. To study this impact, a variety of methodological approaches is used, including theoretical, empirical, model, literature and policy analyses. The study shows that a significant part of the costs of freely allocated CO2 emission allowances is passed through to power prices, resulting in higher electricity prices for consumers and additional ('windfall') profits for power producers. In addition, it discusses some policy implications of the pass-through of these costs. It concludes that the pass-through of CO2 costs to electricity prices is a rational, carbon-efficient policy, while the issue of windfall profits can be addressed by either taxing these profits or auctioning - rather than free allocations - of the emission allowances

  4. Portraits du dégénéré en fou, en primitif, en enfant et finalement en artiste.

    Stéphane Legrand

    2004-04-01

    Full Text Available Cet article traite du concept de « dégénérescence », importé dans la psychiatrie française par Benedict-Auguste Morel dans les années 1850, et largement diffusé par la suite, dans ce champ ainsi que dans celui de la criminologie. On tente d’analyser la reconfiguration qu’impose ce concept au savoir psychiatrique en dégageant la manière dont il permet d’intégrer en un ensemble cohérent plusieurs modèles théoriques: un paradigme neurologique, une théorie de l’automatisme morbide, un certain évolutionnisme. Sur ces bases, on essaie d’établir les similitudes de fonds existant entre les conceptions psychiatrique et criminologique de la dégénérescence, en montrant qu’elles mobilisent le même réseau « structurant » d’analogies entre les figures de l’anormal (le fou, le sauvage, l’enfant, la femme, l’animal; et l’on s’efforce de montrer que ces théories promeuvent une logique dans laquelle les infractions aux différents types de normes (biologiques, sociales, morales, juridiques, psychologiques, économiques sont susceptibles de faire systématiquement référence les unes aux autres, de se traduire les unes dans les autres. Puis l’on caractérise les transformations que ce nouveau paradigme impose aux principes de la thérapeutique, de la pédagogie et de la prise en charge des malades mentaux et des déviants. Pour finir, on présente les éléments latents qui dans ce paradigme préparent et indiquent déjà sa remise en cause et son renversement à venir.This article deals with the concept of «degeneration», introduced by Benedict-Auguste Morel in the French psychiatry during the 1850s, and which widely spread afterwards, in this field as well as in the contemporary criminology. An analysis is tried of the changes imposed by this notion on the psychiatric knowledge, changes that resulted in the integration in a coherent system of three other paradigms: a neurological paradigm, a theory of pathological automatism, a certain kind of evolutionary theory. The author then tries to establish the existence of background similarities between the psychiatric and criminological theories of degeneration, namely in as much as they promote the same «structural» analogies between the various forms of abnormality (the madman, the primitive, the woman, the child, the animal; and it is shown that these theories also imply a logic in which all the transgressions of the different kinds of norms (biological, social, moral, juridical, psychological, economical tend to be systematically referred to one another, and translated into one another. Then a sketch is given of the changes imposed by this paradigm to the principles of therapy and pedagogy for the insane persons. And finally the author presents some of the themes that, in this paradigm, already prepare its deconstruction to come.

  5. Rhizobium grahamii sp. nov., from nodules of Dalea leporina, Leucaena leucocephala and Clitoria ternatea, and Rhizobium mesoamericanum sp. nov., from nodules of Phaseolus vulgaris, siratro, cowpea and Mimosa pudica.

    López-López, Aline; Rogel-Hernández, Marco A; Barois, Isabelle; Ortiz Ceballos, Angel I; Martínez, Julio; Ormeño-Orrillo, Ernesto; Martínez-Romero, Esperanza

    2012-09-01

    Two novel related Rhizobium species, Rhizobium grahamii sp. nov. and Rhizobium mesoamericanum sp. nov., were identified by a polyphasic approach using DNA-DNA hybridization, whole-genome sequencing and phylogenetic and phenotypic characterization including nodulation of Leucaena leucocephala and Phaseolus vulgaris (bean). As similar bacteria were found in the Los Tuxtlas rainforest in Mexico and in Central America, we suggest the existence of a Mesoamerican microbiological corridor. The type strain of Rhizobium grahamii sp. nov. is CCGE 502(T) (= ATCC BAA-2124(T) = CFN 242(T) = Dal4(T) = HAMBI 3152(T)) and that of Rhizobium mesoamericanum sp. nov. is CCGE 501(T) (= ATCC BAA-2123(T) = HAMBI 3151(T) = CIP 110148(T) = 1847(T)). PMID:22081714

  6. Rhizobium sp. strain BN4 (a selenium oxyanion-reducing bacterium) 16S rRNA gene complete sequence

    This study used 1482 base pair 16S rRNA gene sequence methods in conjunction with other biochemical and morphological studies to confirm the identification of a bacterium (refer to as the BN4 strain) as a Rhizobium sp. The 16S rRNA gene sequence places it with the Rhizobium clade that includes R. d...

  7. Draft Genome Sequence of a Phthalate Ester-Degrading Bacterium, Rhizobium sp. LMB-1, Isolated from Cultured Soil

    Tang, Wen-Juan; Zhou, Ying; YE, BANG-CE

    2015-01-01

    Rhizobium sp. LMB-1, newly isolated from greenhouse soil, can effectively degrade phthalate. Here, we present a 5.2-Mb assembly of this Rhizobium sp. genome for the first time. It may provide abundant molecular information for the transformation of phthalates.

  8. Genome Sequence of Rhizobium grahamii CCGE502, a Broad-Host-Range Symbiont with Low Nodulation Competitiveness in Phaseolus vulgaris

    Althabegoiti, M. Julia; Lozano, Luis; Torres-Tejerizo, Gonzalo; Ormeño-Orrillo, Ernesto; Rogel, Marco A.; González, Víctor; Martínez-Romero, Esperanza

    2012-01-01

    Here we present the genome sequence of Rhizobium grahamii CCGE502. R. grahamii groups with other newly described broad-host-range species, which are not very efficient Phaseolus vulgaris symbionts, with a wide geographic distribution and which constitutes a novel Rhizobium clade.

  9. Estudio del plásmido simbiótico de una estirpe de Rhizobium SP (Hedysarum Coronarium)

    Ollero Márquez, Francisco Javier

    1988-01-01

    La estirpe IS 123 de Rhizobium sp. (Hedysarum coronarium) presenta un plásmido simbiótico (230 MD), que se ha marcado con el transposon IN5MOB, comprobándose que es autotransferible, si bien su transferencia a determinadas estirpes de Rhizobium y agrobact

  10. Genetic Factors in Rhizobium Affecting the Symbiotic Carbon Costs of N2 Fixation and Host Plant Biomass Production

    Skøt, L.; Hirsch, P. R.; Witty, J. F.

    1986-01-01

    The effect of genetic factors in Rhizobium on host plant biomass production and on the carbon costs of N2 fixation in pea root nodules was studied. Nine strains of Rhizobium leguminosarum were constructed, each containing one of three symbiotic plasmids in combination with one of three different...

  11. Rhizobium oryzicola sp. nov., potential plant-growth-promoting endophytic bacteria isolated from rice roots.

    Zhang, Xiao-Xia; Gao, Ju-Sheng; Cao, Yan-Hua; Sheirdil, Rizwan Ali; Wang, Xiu-Cheng; Zhang, Lei

    2015-09-01

    Bacterial strains ZYY136(T) and ZYY9 were isolated from surface-sterilized rice roots from a long-term experiment of rice-rice--Astragalus sinicus rotation. The 16S rRNA gene sequences of strains ZYY136(T) and ZYY9 showed the highest similarity, of 97.0%, to Rhizobium tarimense PL-41(T). Sequence analysis of the housekeeping genes recA, thrC and atpD clearly differentiated the isolates from currently described species of the genus Rhizobium. The DNA-DNA relatedness value between ZYY136(T) and ZYY9 was 82.3%, and ZYY136(T) showed 34.0% DNA-DNA relatedness with the most closely related type strain, R. tarimense PL-41(T). The DNA G+C content of strain ZYY136(T) was 58.1 mol%. The major cellular fatty acids were summed feature 8 (C18 : 1?7c and/or C18 : 1?6c), C16 : 0 and C16 : 0 3-OH. Strains ZYY136(T) and ZYY9 could be differentiated from the previously defined species of the genus Rhizobium by several phenotypic characteristics. Therefore, we conclude that strains ZYY136(T) and ZYY9 represent a novel species of the genus Rhizobium, for which the name Rhizobium oryzicola sp. nov. is proposed (type strain ZYY136(T)?= ACCC 05753(T) = KCTC 32088(T)). PMID:26016492

  12. NopC Is a Rhizobium-Specific Type 3 Secretion System Effector Secreted by Sinorhizobium (Ensifer) fredii HH103

    Medina, Carlos; Ollero, Francisco Javier; López-Baena, Francisco Javier

    2015-01-01

    Sinorhizobium (Ensifer) fredii HH103 is a broad host-range nitrogen-fixing bacterium able to nodulate many legumes, including soybean. In several rhizobia, root nodulation is influenced by proteins secreted through the type 3 secretion system (T3SS). This specialized secretion apparatus is a common virulence mechanism of many plant and animal pathogenic bacteria that delivers proteins, called effectors, directly into the eukaryotic host cells where they interfere with signal transduction pathways and promote infection by suppressing host defenses. In rhizobia, secreted proteins, called nodulation outer proteins (Nops), are involved in host-range determination and symbiotic efficiency. S. fredii HH103 secretes at least eight Nops through the T3SS. Interestingly, there are Rhizobium-specific Nops, such as NopC, which do not have homologues in pathogenic bacteria. In this work we studied the S. fredii HH103 nopC gene and confirmed that its expression was regulated in a flavonoid-, NodD1- and TtsI-dependent manner. Besides, in vivo bioluminescent studies indicated that the S. fredii HH103 T3SS was expressed in young soybean nodules and adenylate cyclase assays confirmed that NopC was delivered directly into soybean root cells by means of the T3SS machinery. Finally, nodulation assays showed that NopC exerted a positive effect on symbiosis with Glycine max cv. Williams 82 and Vigna unguiculata. All these results indicate that NopC can be considered a Rhizobium-specific effector secreted by S. fredii HH103. PMID:26569401

  13. Absorción de cobre y características de Leucaena leucocephala asociada con Glomus spp. y Rhizobium en suelo contaminado del Río Lerma, México

    Abdul Khalil Gardezi

    2006-01-01

    Full Text Available El objetivo de esta investigación fue evaluar (a la capacidad de absorción de Cu por Leucaena leucocephala y (b el efecto en sus características agronómicas al inocularse con hongos endomicorrízicos arbusculares y Rhizobium como alternativa para la fitorremediación de suelos agrícolas contaminados. El trabajo se realizó en condiciones de invernadero en suelo contaminado por Cu procedente de la parte alta de la cuenca del río Lerma, estado de México. Las plantas de Leucaena crecieron en bolsas de polietileno negro con 3 kg del suelo contaminado esterilizado o no esterilizado. Se aplicaron 0, 20 y 200 mg de Cu kg-1 de suelo contaminado tratado con Glomus sp. Zac-19, Glomus intraradices o sin Glomus, e inoculado con Rhizobium o sin Rhizobium. Se evaluaron la acumulación de Cu en las plantas, sus características agronómicas y el contenido final de Cu en el suelo. La acumulación de Cu en las plantas fue mayor en tallos que en hojas y se asoció a la disminución de su concentración en el suelo a través del tiempo. No hubo efecto de la esterilización del suelo sobre la acumulación de Cu, ni sobre las características agronómicas de las plantas, excepto sobre el número de nódulos de Rhizobium. Se observó significativamente (P < 0.05 mayor acumulación de Cu al incrementarse su concentración en el suelo, destacando un efecto positivo de 20 mg de Cu kg-1 de suelo al mejorar las características agronómicas. Las plantas con mejores características agronómicas disminuyeron su tendencia a la absorción de Cu en presencia simultánea de Glomus spp. y Rhizobium. Esto demuestra un efecto interactivo positivo de la doble inoculación endomicorriza más Rhizobium en la absorción de Cu por las plantas de Leucaena y aumenta su papel en el diseño de estrategias de reforestación y fitorremediación de suelos agrícolas contaminados por cobre.

  14. Studies on mutation and repair in Rhizobium japonicum

    In the presence of NTG, Rhizobium japonicum loses viability very rapidly. 50% survival is achieved within 4 mins using 50 μgm/ml. When a constant time of 30 min is maintained then a concentration of 18 μgm/ml gives 50% survival. The low doses of NTG did not yield any auxotrophs. The antibiotics like penicillion, ampicillin and streptopenicillin were used as agents for enrichment of mutants, ampicillin was quite effective. A fairly efficient mechanism for repair from U.V. damage appears to exist. A greater part of this repair is due to the prevalence of dark repair mechanism. Mutants with increased sensitivity to U.V. repair failed to transform normally suggesting that the two processes of U.V. repair and genetic recombination may be related. The levels of deoxyribonucleases increased at the competent state. The activity at pH 7.5 and 8.4 but not at 5.5 was greater towards irradiated DNA, a prerequisite for any enzyme involved in U.V. repair. (author)

  15. Effect of Rhizobium Inoculants on Cowpea under Rainfed Condition

    Sarker P. C.

    2001-01-01

    Full Text Available A 2-year on-farm experiment was conducted under rainfed condition to study the effect of Rhizobium inoculation (with or without chemical fertilizer and chemical fertilizer ( 0 and 50-30-20 Kg ha -1 P2O5, K2O and S on cowpea. Two sources of biofertilizer were used. Biofertilizer showed significantly higher yield attributes and seed yield of cowpea as compared to control. Biofertilizer of BARI source gave the highest cowpea seed yield (880 Kg ha -1 and the lowest seed yield (658 Kg ha -1 was obtained without biofertilizer. No significant difference was found between the two sources of bio-fertilizer. Chemical fertilizer showed better performance than control in case of seed yield and all yield contributing characters of cowpea. Interaction of bio-fertilizer and chemical fertilizer also showed statistically significant difference. PKS with biofertilizer of both BAU and BARI sources gave the highest seed yield (987 Kg ha -1 and the lowest seed yield (525 Kg ha -1 was obtained from control treatment. Though the highest average rate of return (4556% was found using biofertilizer of BARI source but on consideration of net return and also soil health, PKS with biofertilizer of BARI source where ARR was the second highest may be suggested for growing cowpea under rainfed condition.

  16. Biologic fixation of nitrogen in irradiated rhizobium strips

    Native Rhizobium sp. and Bradyrhizobium sp. isolates from the root nodules of bean and cowpea were selected. Six isolates, and the SEMIA 4077 (R. leguminosarum bv. phaseolus) and SEMIA 6145 (Bradyrhizobium sp) strains used as references, were irradiated with ultraviolet light (R-uv) and gamma rays (R-γ). The D37 values for the rhizobial strain SEMIA 4077 were 43 J.m-2 (UV) and 32 Gy (R-γ) and for the SEMIA 6145 were 45 J.m-2 (UV) and 35 Gy (R-gamma). Through a greenhouse experiment the irradiated isolates were inoculated on bean (P. vulgaris L., cv. Princesa) and on cowpea [Vigna unguiculata, (L.) Walp, cv. IPA-206] seedlings, in an attempt to evaluate the sensitivity of the host plants, and possible effects on their nodulation. Differences in responses to nodulation due to the effect of irradiation were observed for the isolates tested. Significantly differences were observed only for nodules dry matter yield of the IPA-206 cultivar. Gamma irradiated treatment were statistically superior to treatments with ultraviolet light in relation. (author)

  17. Analysis of the proteome of common bean (Phaseolus vulgaris L.) roots after inoculation with Rhizobium etli.

    Salavati, Afshin; Taleei, Alireza; Bushehri, Ali Akbar Shahnejat; Komatsu, Setsuko

    2012-08-01

    Proteomics techniques were used to identify the underlying mechanism of the early stage of symbiosis between the common bean (Phaseolus vulgaris L.) and bacteria. Proteins from roots of common beans inoculated with bacteria were separated using two-dimensional polyacrylamide gel electrophoresis and identified using mass spectrometry. From 483 protein spots, 29 plant and 3 bacterial proteins involved in the early stage of symbiosis were identified. Of the 29 plant proteins, the expression of 19 was upregulated and the expression of 10 was downregulated. Upregulated proteins included those involved in protein destination/storage, energy production, and protein synthesis; whereas the downregulated proteins included those involved in metabolism. Many upregulated proteins involved in protein destination/storage were chaperonins and proteasome subunits. These results suggest that defense mechanisms associated with induction of chaperonins and protein degradation regulated by proteasomes occur during the early stage of symbiosis between the common bean and bacteria. PMID:22762188

  18. [The Effect of Cadmium on the Efficiency of Development of Legume-Rhizobium Symbiosis].

    Chuhukova, O V; Postrigan, B N; Baimiev, A Kh; Chemeris, A V

    2015-01-01

    Screening of nodule bacteria (rhizobia) forming symbiotic relationships with legumes has been performed in order to isolate strains resistant to cadmium ions in a wide range of concentrations (6-132 mg/kg). The effect ofcadmium salts (6, 12, 24 mg/kg) on the legume-rhizobium symbiosis ofthe pea Pisum sativum L. with Rhizobium leguminosarum and of the fodder galega Galega orientalis Lam. with Rhizobium galegae has been studied under experimental laboratory conditions. No statistically significant differences have been revealed in the growth and biomass of plants with regard to the control in the range of concentrations given above. However, it was found that cadmium inhibited nodulation in P. sativum and stimulated it in G. orientalis. PMID:26638242

  19. Cultivar and Rhizobium Strain Effects on the Symbiotic Performance of Pea (Pisum sativum)

    Skøt, Leif

    1983-01-01

    The symbiotic performance of four pea (Pisum sativum L.) cultivars in combination with each of four strains of Rhizobium leguminosarum was studied in growth chamber experiments in order to estimate the effects of cultivars, strains and cultivar × strain interaction on the variation in dry weight, N...... content and dry weight/N ratio. At harvest 63 days after planting, cultivars accounted for 75% of the variation in dry weight, while the Rhizobium strains accounted for 63% of the variation in N-content and 70% of the variation in dry weight/N ratio. Cultivar × strain interactions were statistically...... significant, but of minor quantitative importance, accounting for 5–15% of the total variation. Rhizobium strains also influenced the partitioning of N between reproductive and vegetative plant parts and between root and shoot biomass....

  20. Phylogenetic grouping and identification of Rhizobium isolates on the basis of random amplified polymorphic DNA profiles.

    Dooley, J J; Harrison, S P; Mytton, L R; Dye, M; Cresswell, A; Skot, L; Beeching, J R

    1993-07-01

    Through the use of a single, random 15mer as a primer, between 1 and 12 DNA amplification products were obtained per strain from a selection of 84 Rhizobium and Bradyrhizobium isolates. A principal-coordinate analysis was used to analyse the resulting amplified DNA profiles and it was possible to assign isolates to specific groupings. Within the species Rhizobium leguminosarum, the biovar phaseoli formed a distinct group from the other biovars of the species, viciae and trifolii, which grouped together. Isolates of Rhizobium meliloti and Bradyrhizobium species formed their own clear, specific groups. Although it was possible to identify individual isolates on the basis of differences in their amplified DNA profiles, there was evidence that some amplified segments were conserved among individuals at the biovar and species levels. PMID:8364802

  1. The isolation, enumeration, and characterization of Rhizobium bacteria of the soil in Wamena Biological Garden

    SRI PURWANINGSIH

    2005-04-01

    Full Text Available The eleven soil samples have been isolated and characterized. The aims of the study were to get the pure culture and some data which described about enumeration and especially their characters in relation to the acids and bases reaction in their growth. The isolation of the bacteria use Yeast Extract Mannitol Agar medium (YEMA while the characterization by using YEMA medium mixed with Brom Thymol Blue and Congo Red indicators respectively. The results showed that eighteen isolates have been isolated which consisted of three low growing and fifteen fast growing bacteria. Two isolates were not indicated Rhizobium and sixteen were Rhizobium. Density of Rhizobium enumeration was varied which related to soil organic matter content. The enumeration bacteria in YEMA medium were in the range of 0.6 x 105 and 11.6 x 105 CFU /g soil. The highest population was found in soil sample of Wieb vegetation.

  2. Yield response of fidders (berseem, shaftal, and lucerne) to rhizobium inclulation

    Investigations were carried out to know the effect of Rhizobium inoculation on the fodder yield and nitrogen fixation of berseem, shaftal and lucerne in y clay loam soil in a pot culture experiment. A basal dressing of nitrogen, phosphorus (P/sub 2/O/sub 5/) and Potash (K/sub 2/O) at 20,80,40 Kg/ha as urea, single superphosphate and potassium sulphate were applied to each pot. The results revealed that Rhizobium inoculation significantly increased the green fodder yield in four cuttings of berseem by 35 to 147 percent of shaftal by 41 to 60 percent and of lucerne by 41 to 74 percent. Shoos N-yield in four cuttings exhibited a significant increasing trend by 21 to 158 percent in berseem, 40 to 69 percent in shaftal and 41 to 78 percent in lucerne due to biological nitrogen fixation as a result of Rhizobium inoculation. (author)

  3. Herbivores alter the fitness benefits of a plant-rhizobium mutualism

    Heath, Katy D.; Lau, Jennifer A.

    2011-03-01

    Mutualisms are best understood from a community perspective, since third-party species have the potential to shift the costs and benefits in interspecific interactions. We manipulated plant genotypes, the presence of rhizobium mutualists, and the presence of a generalist herbivore and assessed the performance of all players in order to test whether antagonists might alter the fitness benefits of plant-rhizobium mutualism, and vice versa how mutualists might alter the fitness consequences of plant-herbivore antagonism. We found that plants in our experiment formed more associations with rhizobia (root nodules) in the presence of herbivores, thereby increasing the fitness benefits of mutualism for rhizobia. In contrast, the effects of rhizobia on herbivores were weak. Our data support a community-dependent view of these ecological interactions, and suggest that consideration of the aboveground herbivore community can inform ecological and evolutionary studies of legume-rhizobium interactions.

  4. Effect of Rhizobium and Mycorhiza inoculation on the nursery growth of Acacia and Teline monspessulana

    In an experiment accomplished in the tree nursery Tisquesusa located in Madrid (Cundinamarca) was evaluated the effect of the inoculation with strains selected of foreign and Indigenous rhizobium and Arbuscular mycorrhizal fungi am (Glomus folescutolum) on the growth, nitrogen fixation, and micorrization of Acacia (Acacia decurrens) and Retamo (Teline monspessulana) that they are used In soils recovery by the Corporacion Autonoma Regional de Cundinamarca CAR. The studied species presented positive response to the inoculation with rhizobium; the indigenous strain DQ6-09, isolated in Guatavita (Cundinamarca), presented the better results in Retamo and also in Acacia alone and in mixture with the foreign strain T1881. The inoculation with fungi AM increased the heights, dry weights, phosphorus content and percentage of micorrization in Acacia and Retamo. The double inoculation with fungi ma and rhizobium it did not increase the nitrogen fixing of Acacia while in Retamo was presented a positive effect with the strain DQ6-09

  5. Rhizobium nepotum sp. nov. isolated from tumors on different plant species.

    Puławska, Joanna; Willems, Anne; De Meyer, Sofie E; Süle, Sandor

    2012-06-01

    Five Gram-negative, rod-shaped, non-spore-forming bacteria were isolated from galls on different plant species in Hungary: strain 39/7(T) from Prunus cerasifera Myrobalan, strain 0 from grapevine var. Ezerjó, strain 7/1 from raspberry var. Findus and in Poland, strain C3.4.1 from Colt rootstock (Prunus avium × Prunus pseudocerasus) and strain CP17.2.2 from Prunus avium. Only one of these isolates, strain 0, is able to cause crown gall on different plant species. On the basis of 16S rRNA gene sequence similarity, the strains cluster together and belong to the genus Rhizobium and their closest relative is Rhizobium radiobacter (99.1%). Phylogenetic analysis of the novel strains using housekeeping genes atpD, glnA, gyrB, recA and rpoB revealed their distinct position separate from other known Rhizobium species and confirmed their relation to Rhizobium radiobacter. The major cellular fatty acids are 18:1 w7c, 16:0, 16:0 3OH, summed feature 2 (comprising 12:0 aldehyde, 16:1 iso I and/or 14:0 3OH) and summed feature 3 (comprising 16:1 w7c and/or 15 iso 2OH). DNA-DNA hybridization of strain 39/7(T) with the type strain of R. radiobacter LMG 140(T) revealed 45% DNA-DNA hybridization. Phenotypic and physiological properties differentiate the novel isolates from other closely related species. On the basis of the results obtained, the five isolates are considered to represent a novel species of the genus Rhizobium, for which the name Rhizobium nepotum sp. nov. (type strain 39/7(T)=LMG 26435(T)=CFBP 7436(T)) is proposed. PMID:22463808

  6. Genetic characterization and nitrogen fixation capacity of Rhizobium strains on common bean Caracterização genética e capacidade de fixação de nitrogênio de estirpes de Rhizobium em feijoeiro

    Tehuni Orlando González

    2008-09-01

    Full Text Available This study aimed to genetically characterize four new Rhizobium strains, and to evaluate their nodulation and fixation capacity compared to commercial strains and to native rhizobia population of a Brazilian Rhodic Hapludox. Two experiments were carried out in randomized blocks design, under greenhouse conditions, in 2007. In the first experiment, the nodulation and nitrogen fixation capacity of new strains were evaluated, in comparison to the commercial strains CIAT-899 and PRF-81 and to native soil population. It was carried out in plastic tubes filled with vermiculite. DNA extractions and PCR sequencing of the intergenic space were made from the isolated pure colonies, in order to genetically characterize the strains and the native rhizobia population. In the second experiment, the nodulation and productivity of common beans Perola cultivar were determined, with the use of evaluated strains, alone or in mixture with PRF-81 strain. It was carried out in pots filled with soil. The native soil population was identified as Rhizobium sp. and was inefficient in nitrogen fixation. Three different Rhizobium species were found among the four new strains. The LBMP-4BR and LBMP-12BR new strains are among the ones with greatest nodulation and fixation capacity and exhibit differential responses when mixed to PRF-81.O objetivo deste trabalho foi a caracterização genética de quatro novas estirpes de Rhizobium e a avaliação de sua capacidade de fixação de N2 e nodulação, comparadas a estirpes comerciais e à população nativa de rizóbios de um Latossolo Vermelho. Dois experimentos foram conduzidos em blocos ao acaso, em casa de vegetação. No primeiro experimento, conduzido em tubetes com vermiculita, avaliaram-se a nodulação e a capacidade de fixação das novas estirpes, em comparação com as estirpes comerciais CIAT-899 e PRF-81 e com a população nativa do solo. Das colônias puras isoladas, extraiu-se o DNA genômico e realizou-se o seqüenciamento do espaço intergênico, para a caracterização genética das estirpes e da população nativa de rizóbios. O segundo experimento foi realizado em vasos com solo, para determinação da produtividade e da nodulação do feijoeiro, cultivar Pérola, com o uso das estirpes isoladamente ou em mistura com a PRF-81. A população nativa do solo foi identificada como Rhizobium sp. e se mostrou ineficiente na fixação de nitrogênio. Foram encontradas três espécies de Rhizobium entre as quatro novas estirpes. As estirpes LBMP-4BR e LBMP-12BR estão entre as que têm maior capacidade de nodulação e fixação de N2, e apresentam respostas diferenciadas quando misturadas à PRF-81.

  7. Rhizobium multihospitium sp. nov., isolated from multiple legume species native of Xinjiang, China.

    Han, Tian Xu; Wang, En Tao; Wu, Li Juan; Chen, Wen Feng; Gu, Jin Gang; Gu, Chun Tao; Tian, Chang Fu; Chen, Wen Xin

    2008-07-01

    Thirty-one rhizobial strains isolated from nodules of legumes native of Xinjiang, China, were characterized. These strains were classified as belonging to the genus Rhizobium based on amplified 16S rDNA restriction analysis (ARDRA). The strains were distinguished from recognized Rhizobium species using analysis of 16S-23S rDNA intergenic spacers (IGS-RFLP), SDS-PAGE analysis of whole proteins and BOX-PCR; the test strains always formed a distinct cluster with patterns that were quite different from those of the reference rhizobial strains used. According to the phylogenetic analysis based on the 16S rRNA gene, the test strains belonged to the genus Rhizobium, with Rhizobium tropici, Rhizobium rhizogenes and Rhizobium lusitanum as the closest related species, with 99.6, 99.2 and 99.4 % sequence similarities, respectively, between the type strains of the three Rhizobium species and strain CCBAU 83401(T). Phylogenetic analyses of the representative strains using IGS and atpD, recA and glnII genes all confirmed the phylogenetic arrangements obtained using the 16S rRNA gene. The DNA-DNA relatedness values between strain CCBAU 83401(T) and strains CCBAU 83364, CCBAU 83345 and CCBAU 83523 ranged from 80.8 to 100 %, showing that they belong to the same species. The DNA-DNA relatedness between strain CCBAU 83401(T) and R. tropici IIB CIAT 899(T), R. tropici IIA CFN 299, R. rhizogenes LMG 150(T) and R. lusitanum P1-7(T) were 26.9, 27.7, 38.2 and 22.6 %, respectively, clearly indicating that strain CCBAU 83401(T) represents a novel species. Phenotypic characterization of four representative strains, CCBAU 83401(T), CCBAU 83364, CCBAU 83345 and CCBAU 83523, showed several distinctive features that differentiated them from closely related species. The 31 strains had identical nodD and nifH genes, which were very similar to those of the bean-nodulating R. lusitanum, Devosia neptuniae and R. tropici IIB. Based upon these results, the strains from this study are considered to represent a novel species, for which the name Rhizobium multihospitium sp. nov. is proposed. The DNA G+C content ranged from 65.3 to 66.0 mol% (T(m)). The type strain is CCBAU 83401(T) (=LMG 23946(T)=HAMBI 2975(T)), which nodulates Robinia pseudoacacia, but not Leucaena leucocephala, Phaseolus vulgaris, Pisum sativum or Medicago sativa. PMID:18599718

  8. Rhizobium acidisoli sp. nov., isolated from root nodules of Phaseolus vulgaris in acid soils.

    Román-Ponce, Brenda; Jing Zhang, Yu; Soledad Vásquez-Murrieta, María; Hua Sui, Xin; Feng Chen, Wen; Carlos Alberto Padilla, Juan; Wu Guo, Xian; Lian Gao, Jun; Yan, Jun; Hong Wei, Ge; Tao Wang, En

    2016-01-01

    Two Gram-negative, aerobic, non-motile, rod-shaped bacterial strains, FH13T and FH23, representing a novel group of Rhizobium isolated from root nodules of Phaseolus vulgaris in Mexico, were studied by a polyphasic analysis. Phylogeny of 16S rRNA gene sequences revealed them to be members of the genus Rhizobium related most closely to 'Rhizobium anhuiense' CCBAU 23252 (99.7 % similarity), Rhizobium leguminosarum USDA 2370T (98.6 %), and Rhizobium sophorae CCBAU 03386T and others ( ≤ 98.3 %). In sequence analyses of the housekeeping genes recA, glnII and atpD, both strains formed a subclade distinct from all defined species of the genus Rhizobium at sequence similarities of 82.3-94.0 %, demonstrating that they represented a novel genomic species in the genus Rhizobium. Mean levels of DNA-DNA relatedness between the reference strain FH13T and the type strains of related species varied between 13.0 ± 2.0 and 52.1 ± 1.2 %. The DNA G+C content of strain FH13T was 63.5 mol% (Tm). The major cellular fatty acids were 16 : 0, 17 : 0 anteiso, 18 : 0, summed feature 2 (12 : 0 aldehyde/unknown 10.928) and summed feature 8 (18 : 1ω7c). The fatty acid 17 : 1ω5c was unique for this strain. Some phenotypic features, such as failure to utilize adonitol, l-arabinose, d-fructose and d-fucose, and ability to utilize d-galacturonic acid and itaconic acid as carbon source, could also be used to distinguish strain FH13T from the type strains of related species. Based upon these results, a novel species, Rhizobium acidisoli sp. nov., is proposed, with FH13T ( = CCBAU 101094T = HAMBI 3626T = LMG 28672T) as the type strain. PMID:26530784

  9. Influence of carbofuran on certain metabolic and symbiotic activities of a cowpea Rhizobium

    Using carbon 14 radioisotope an in-vitro study of the effect of insecticides, carbofuran, on the metabolic and symbiotic activities of Rhizobium sp. cowpea group, was carried out. The study indicated that at 10 ppm carbofuran inhibited the in-vitro growth of the bacterium, suppressed the oxidation of all the Trichloroacetic acid (TCA) cycle intermediates, significantly reduced glucose oxidation and translocation and affected the growth and symbiotic activities of the cowpea as reflected by a reduction in the dry matter production and total nitrogen content. The insecticide was itself degraded by the Rhizobium sp. within 30 days of incubation

  10. Antimicrobial activity of Rhizobium sp. strains against Pseudomonas savastanoi, the agent responsible for the olive knot disease in Algeria

    2009-06-01

    Full Text Available In the present investigation, six Rhizobium strains isolated from Algerian soil were checked for their antimicrobial activity against Pseudomonas savastanoi, the agent responsible for olive knot disease. Rhizobium sp. ORN 24 and ORN 83 were found to produce antimicrobial activities against Pseudomonas savastanoi. The antimicrobial activity produced by Rhizobium sp. ORN24 was precipitable with ammonium sulfate, between 1,000 and 10,000 KDa molecular weight, heat resistant but sensitive to proteases and detergents. These characteristics suggest the bacteriocin nature of the antimicrobial substance produced by Rhizobium sp. ORN24, named rhizobiocin 24. In contrast, the antimicrobial activity produced by Rhizobium sp. ORN83 was not precipitable with ammonium sulfate; it was smaller than 1,000 KDa molecular weight, heat labile, and protease and detergent resistant. These characteristics could indicate the relationship between the antimicrobial substance produced by Rhizobium sp. ORN 83 and the “small” bacteriocins described in other rhizobia.

    En la presente investigación, seis cepas de Rhizobium aisladas de suelos argelinos fueron estudiadas para conocer su actividad antimicrobiana contra Pseudomonas savastanoi, el agente causante de la tuberculosis del olivo. Rhizobium sp. ORN 24 y ORN 83 produjeron actividad antimicrobiana contra Pseudomonas savastanoi. La actividad antimicrobiana producida por Rhizobium sp. ORN 24 precipitó con sulfato amónico, tuvo un peso molecular entre 1000 y 10000 KDa, fue resistente al calor pero sensible a proteasas y detergentes. Estas características sugieren que la sustancia antimicrobial producida por Rhizobium sp. ORN 24 es la bacteriocina natural conocida como rizobiocina 24. Por el contrario, la actividad antimicrobiana producida por Rhizobium sp. ORN83 no fue precipitable con sulfato amónico, y tuvo un peso molecular menor de 1000 KDa, fue lábil al calor y resistente a detergentes y proteasas. Estas características podrían indicar una relación de la sustancia antimicrobiana producida por Rhizobium sp. ORN83 con la “pequeña” bacteriocina descrita en otros Rhizobium.

  11. Dualité, Triadicité et Signification en mathématiques: ou Pourquoi Granger ne peut finalement pas être peircien

    Tiercelin, Claudine

    1995-01-01

    Analyse des relations entre certaines conceptions mathématiques et sémantiques de Peirce et de Granger (rôle des icônes et des symboles notamment dans la déduction, illusoire dissociation du sémantique et du syntaxique, importance du registre de l'illocutoire).L'article montre pourquoi Granger ne peut pas, en définitive, être totalement peircien.

  12. Sobrevivência e nodulação do Rhizobium tropici em sementes de feijão tratadas com fungicidas Survival and nodulation of Rhizobium tropici on common bean seeds treated with fungicides

    Ademir Sérgio Ferreira de Araújo; Ricardo Silva Araújo

    2006-01-01

    O objetivo deste trabalho foi avaliar a sobrevivência e a capacidade de nodulação do Rhizobium tropici em sementes de feijão tratadas com fungicidas. O estudo foi realizado em laboratório e em casa de vegetação. Sementes de feijão (Phaseolus vulgaris) foram tratadas com seis diferentes fungicidas e inoculadas com Rhizobium tropici estirpe CIAT 899. A sobrevivência do Rhizobium nas sementes foi avaliada no tempo 0 e 24 horas após o tratamento com fungicidas e a inoculação, utilizando o método ...

  13. Galactosyl residue in exopolysaccharide from Rhizobium meliloti JJ-1 exposed to manganese in furanoid.

    Appanna, V D

    1989-11-01

    Exopolysaccharide (EPS) elaborated by Rhizobium meliloti JJ-1 in a manganese supplemented medium was isolated. Periodate oxidation, reduction with sodium borohydride, followed by hydrolysis and subsequent capillary gas liquid chromatography of the derived alditol acetates revealed that D-galactose in this complex biopolymer is in furanoid form. This observation was further confirmed by 13carbon nuclear magnetic resonance (13C NMR). PMID:2619288

  14. Mineral Composition of Red Clover under Rhizobium Inoculation and Lime Application in Acid Soil

    Olivera STAJKOVIĆ-SRBINOVIĆ

    2015-12-01

    Full Text Available In the present study the effects of Rhizobium inoculation and lime application on the mineral composition (N, P, K, Ca, Mg, Fe, Mn, Cu, Zn, B of red clover (Trifolium pratense L., in very acid soil were evaluated. Inoculation with Rhizobium leguminosarum bv. trifolii significantly increased shoot dry weight (SDW of red clover plants (three times greater, as well as N, Mg, Fe, Mn and Cu contents in plants compared to the control. Application of lime and Rhizobium together, depending on the lime rate (3, 6 or 9 t ha-1 of lime and the cut, increased SDW significantly, but decreased the contents of N, P, K, Mg, Mn, Zn and B in plants. Regardless of the changes, in all treatments in both cuts, contents of N, K, Ca, Mg, Mn and Zn in plants were among sufficiency levels (Mg content was elevated in the second cut, while Fe content was mainly high, as well as Cu (in the second cut. Contents of P and B in plants were somewhat lower than sufficiency levels, but above critical level. Therefore, red clover can be grown with satisfactory yield and mineral composition in acid soil with Rhizobium inoculation only, but the application of P and B fertilization is desirable.

  15. Enrichment, isolation, and characterization of 4-chlorophenol-degrading bacterium Rhizobium sp. 4-CP-20.

    Yang, Chu-Fang; Lee, Chi-Mei

    2008-06-01

    The objectives of this research were to monitor the variations of species in mixed cultures during the enrichment period, isolate species and identify and characterize the pure 4-chlorophenol (4-CP) degrading strains from enriched mixed cultures. Strain Rhizobium sp. 4-CP-20 was isolated from the acclimated mixed culture. The DGGE result indicated that strain Rhizobium sp. 4-CP-20 was undetectable at the beginning but detectable after 2 weeks of enrichment. The optimum growth temperatures for Rhizobium sp. 4-CP-20 were both 36 degrees C using 350 mg l(-1) glucose or sodium acetate as the substrate. The optimum pH range for degrading 100 mg l(-1) 4-CP was between 6.89 and 8.20. Strain Rhizobium sp. 4-CP-20 could degrade 4-CP completely within 3.95 days, as the initial 4-CP concentration was 100 mg l(-1). If the initial 4-CP concentration was higher than 240 mg l(-1), the growth of bacterial cells and the activity of degrading 4-CP were both inhibited. PMID:17636393

  16. Rhizobium borbori sp. nov., aniline-degrading bacteria isolated from activated sludge.

    Zhang, Guo Xia; Ren, Sui Zhou; Xu, Mei Ying; Zeng, Guo Qu; Luo, Hui Dong; Chen, Jin Lin; Tan, Zhi Yuan; Sun, Guo Ping

    2011-04-01

    Three aniline-degrading bacteria, strains DN316(T), DN316-1 and DN365, were isolated from activated sludge. According to 16S rRNA gene sequence-based phylogenetic analysis, the isolates belonged to the genus Rhizobium, with Rhizobium (?=?Agrobacterium) radiobacter LMG 140(T) as the closest relative, with 96.5?% sequence similarity. Phylogenetic analysis of the representative strain DN316(T) using sequences of the glnA, thrC and recA genes and the 16S-23S intergenic spacer region confirmed the phylogenetic arrangement obtained from analysis of the 16S rRNA gene. DNA-DNA relatedness between DN316(T) and R. radiobacter LMG 140(T) was 43.7?%, clearly indicating that the representative strain DN316(T) represents a novel species. Phenotypic and biochemical characterization of the isolates and insertion sequence-PCR fingerprinting patterns showed several distinctive features that differentiated them from closely related species. The major components of the cellular fatty acids were C(18?:?1)?7c (57.10?%), C(16?:?0) (11.31?%) and C(19?:?0) cyclo ?8c (10.13?%). Based on our taxonomic analysis, the three isolates from activated sludge represent a novel species of the genus Rhizobium, for which the name Rhizobium borbori sp. nov. is proposed. The type strain is DN316(T) (?=?CICC 10378(T) ?=?LMG 23925(T)). PMID:20453105

  17. Three cases of post-cataract surgery endophthalmitis due to Rhizobium (Agrobacterium) radiobacter.

    Moreau-Gaudry, Viviane; Chiquet, Christophe; Boisset, Sandrine; Croize, Jacques; Benito, Yvonne; Cornut, Pierre Loïc; Bron, Alain; Vandenesch, François; Maurin, Max

    2012-04-01

    We present three unrelated post-cataract surgery endophthalmitis cases caused by Rhizobium radiobacter, hospitalized in three different hospitals. Early diagnosis was obtained in two cases by bacterial DNA detection in vitreous samples. All patients recovered from infection, but pars plana vitrectomy was needed in two patients due to rapid clinical deterioration. PMID:22259203

  18. Analysis of Rhizobium meliloti Sym Mutants Obtained by Heat Treatment †

    Toro, Nicolas; Olivares, José

    1986-01-01

    Deletions in the pSym megaplasmid of Rhizobium meliloti were produced at a high frequency, and their lengths varied according to incubation temperature. Morphological differentiation into large and small colonies occurred after heat treatment. Small colonies elicited pseudonodules on alfalfa roots.

  19. Free-Living Rhizobium Strain Able to Grow on N2 as the Sole Nitrogen Source

    1983-01-01

    A Rhizobium strain isolated from stem nodules of the legume Sesbania rostrata was shown to grow on atmospheric nitrogen (N2) as the sole nitrogen source. Non-N2-fixing mutants isolated directly on agar plates formed nodules that did not fix N2 when inoculated into the host plant.

  20. Reduction of Selenite to Elemental Red Selenium by Rhizobium sp. strain B1

    bacterium that reduces the soluble and toxic selenite anion to insoluble elemental red selenium (Se0) was isolated from a laboratory bioreactor. Biochemical, morphological, and 16S rRNA gene sequence alignment identify the isolate as a Rhizobium sp. that is related to but is genetically divergent ...

  1. Estudio genético de la nodulación de "Rhizobium fredii"

    Romero Portillo, Francisco

    1993-01-01

    En esta tesis se han estudiado diversos aspectos de la nodulación de las estirpes de Rhizobium fredii. Esta especie está constituida por diferentes estirpes que se caracterizan por ser de crecimiento rápido (2 a 4 horas de tiempo de generación) y por nodu

  2. Cultivar and Rhizobium Strain Effects on the Symbiotic Performance of Pea (Pisum sativum)

    Skøt, Leif

    1983-01-01

    The symbiotic performance of four pea (Pisum sativum L.) cultivars in combination with each of four strains of Rhizobium leguminosarum was studied in growth chamber experiments in order to estimate the effects of cultivars, strains and cultivar × strain interaction on the variation in dry weight, N...

  3. Danish Rhizobium leguminosarum strains nodulating ‘Afghanistan’ pea (Pisum sativum)

    Jensen, Erik Steen; Sørensen, Lasse Holst; Engvild, Kjeld Christensen

    1986-01-01

    A wild pea (Pisum sativum L.) native to Afghanistan normally known to be resisant to nodulation with European strains of Rhizobium leguminosarum was nodulated early and effectively in field soil in Denmark. Isolates from nodules formed effective nodules abundantly on 'Afghanistan' on reinfection...

  4. Visualization of Nodulation Gene Activity on the Early Stages of Rhizobium leguminosarum bv. viciae Symbiosis

    Chovanec, Pavel; Novák, Karel

    2005-01-01

    Roč. 50, č. 4 (2005), s. 323-331. ISSN 0015-5632 R&D Projects: GA ČR GA521/03/0192 Institutional research plan: CEZ:AV0Z50200510 Keywords : nodulation * rhizobium leguminosarum * vicia tetrasperma Subject RIV: EE - Microbiology, Virology Impact factor: 0.918, year: 2005

  5. YIELD RESPONSE OF VALENCIA PEANUT WITH DIFFERENT ROW ORIENTATIONS, NITROGEN RATES AND RHIZOBIUM INOCULUM

    Peanut grown in the southeast with twin row orientation has shown an increase in yield and grade over conventional single row. Peanut farmers in New Mexico do not use rhizobium inoculum at the time of planting, but do apply high rates of nitrogen fertilizer (300 to 350 kg ha-1). A study was conduct...

  6. Rhizobium anhuiense sp. nov., isolated from effective nodules of Vicia faba and Pisum sativum.

    Zhang, Yu Jing; Zheng, Wen Tao; Everall, Isobel; Young, J Peter W; Zhang, Xiao Xia; Tian, Chang Fu; Sui, Xin Hua; Wang, En Tao; Chen, Wen Xin

    2015-09-01

    Four rhizobia-like strains, isolated from root nodules of Pisum sativum and Vicia faba grown in Anhui and Jiangxi Provinces of China, were grouped into the genus Rhizobium but were distinct from all recognized species of the genus Rhizobium by phylogenetic analysis of 16S rRNA and housekeeping genes. The combined sequences of the housekeeping genes atpD, recA and glnII for strain CCBAU 23252(T) showed 86.9 to 95% similarity to those of known species of the genus Rhizobium. All four strains had nodC and nifH genes and could form effective nodules with Pisum sativum and Vicia faba, and ineffective nodules with Phaseolus vulgaris, but did not nodulate Glycine max, Arachis hypogaea, Medicago sativa, Trifolium repens or Lablab purpureus in cross-nodulation tests. Fatty acid composition, DNA-DNA relatedness and a series of phenotypic tests also separated these strains from members of closely related species. Based on all the evidence, we propose a novel species, Rhizobium anhuiense sp. nov., and designate CCBAU 23252(T) ( = CGMCC 1.12621(T) = LMG 27729(T)) as the type strain. This strain was isolated from a root nodule of Vicia faba and has a DNA G+C content of 61.1 mol% (Tm). PMID:26025940

  7. Rhizobium Lipo-chitooligosaccharide Signaling Triggers Accumulation of Cytokinins in Medicago truncatula Roots.

    van Zeijl, Arjan; Op den Camp, Rik H M; Deinum, Eva E; Charnikhova, Tatsiana; Franssen, Henk; Op den Camp, Huub J M; Bouwmeester, Harro; Kohlen, Wouter; Bisseling, Ton; Geurts, René

    2015-08-01

    Legume rhizobium symbiosis is initiated upon perception of bacterial secreted lipo-chitooligosaccharides (LCOs). Perception of these signals by the plant initiates a signaling cascade that leads to nodule formation. Several studies have implicated a function for cytokinin in this process. However, whether cytokinin accumulation and subsequent signaling are an integral part of rhizobium LCO signaling remains elusive. Here, we show that cytokinin signaling is required for the majority of transcriptional changes induced by rhizobium LCOs. In addition, we demonstrate that several cytokinins accumulate in the root susceptible zone 3 h after rhizobium LCO application, including the biologically most active cytokinins, trans-zeatin and isopentenyl adenine. These responses are dependent on calcium- and calmodulin-dependent protein kinase (CCaMK), a key protein in rhizobial LCO-induced signaling. Analysis of the ethylene-insensitive Mtein2/Mtsickle mutant showed that LCO-induced cytokinin accumulation is negatively regulated by ethylene. Together with transcriptional induction of ethylene biosynthesis genes, it suggests a feedback loop negatively regulating LCO signaling and subsequent cytokinin accumulation. We argue that cytokinin accumulation is a key step in the pathway leading to nodule organogenesis and that this is tightly controlled by feedback loops. PMID:25804975

  8. Nodulation of Sesbania Species by Rhizobium (Agrobacterium) Strain IRBG74 and Other Rhizobia

    Concatenated sequence analysis with 16S rRNA, rpoB and fusA genes identified a strain (IRBG74) isolated from root nodules of the aquatic legume Sesbania cannabina as a close relative of the plant pathogen Rhizobium radiobacter (syn. Agrobacterium tumefaciens). However, DNA:DNA hybridisation with R. ...

  9. Parallel variation in isoenzyme and nitrogen fixation markers in a Rhizobium population

    Engvild, K.C.; Jensen, E.S.; Skøt, L.

    1990-01-01

    Twenty isolates of Rhizobium leguminosarum bv. viceae were isolated at random from one field and examined for symbiotic plasmid fragment length polymorphisms and for isoenzyme patterns. The latter are most probably chromosome markers. With one exception both methods separated the isolates into the...

  10. Rhizobium Strain Effects on Yield and Bleeding Sap Amino Compounds in Pisum sativum

    Rosendahl, Lis

    1984-01-01

    for a higher percentage of the organic solutes transporting newly assimilated N from the root system than in the association with 1044. The Rhizobium strain effect on amino compound composition of the bleeding sap may indicate an influence of the bacteroids on either the N-assimilatory enzyme system...

  11. Rhizobium selenireducens sp. nov. Validation and inclusion onto the list of organisms with standing in nomenclature.

    This is a submission to the list of microorganisms with standing in nomenclature. The list of valid microbial names is maintained by the International Journal of Systematic and Evolutionary Microbiology and we are proposing that Rhizobium selenireducens sp. nov. be added to the list as a valid spec...

  12. Response of Andean and Mesoamerican common bean genotypes to inoculation with rhizobium strains.

    In most common bean (Phaseolus vulgaris L.) production regions of Latin America, inoculants are rarely used by farmers in spite of several studies that demonstrate the importance of Rhizobium inoculation on commercial production of legume crops. This study investigated specific bean host plant-Rhizo...

  13. Rhizobium marinum sp. nov., a malachite-green-tolerant bacterium isolated from seawater.

    Liu, Yang; Wang, Run-Ping; Ren, Chong; Lai, Qi-Liang; Zeng, Run-Ying

    2015-12-01

    A motile, Gram-stain-negative, non-pigmented bacterial strain, designated MGL06T, was isolated from seawater of the South China Sea on selection medium containing 0.1 % (w/v) malachite green. Strain MGL06T showed highest 16S rRNA gene sequence similarity to Rhizobium vignae CCBAU 05176T (97.2 %), and shared 93.2-96.9 % with the type strains of other recognized Rhizobium species. Phylogenetic analyses based on 16S rRNA and housekeeping gene sequences showed that strain MGL06T belonged to the genus Rhizobium. Mean levels of DNA-DNA relatedness between strain MGL06T and R. vignae CCBAU 05176T, Rhizobium huautlense S02T and Rhizobium alkalisoli CCBAU 01393T were 20 ± 3, 18 ± 2 and 14 ± 3 %, respectively, indicating that strain MGL06T was distinct from them genetically. Strain MGL06T did not form nodules on three different legumes, and the nodD and nifH genes were also not detected by PCR or based on the draft genome sequence. Strain MGL06T contained Q-10 as the predominant ubiquinone. The major fatty acid was C18 : 1ω7c/C18 : 1ω6c with minor amounts of C19 : 0 cyclo ω8c, C16 : 0 and C18 : 1ω7c 11-methyl. Polar lipids of strain MGL06T included unknown glycolipids, phosphatidylcholine, aminolipid, phosphatidylglycerol, phosphatidylethanolamine, diphosphatidylglycerol, an unknown polar lipid and aminophospholipid. Based on its phenotypic and genotypic data, strain MGL06T represents a novel species of the genus Rhizobium, for which the name Rhizobium marinum sp. nov. is proposed. The type strain is MGL06T ( = MCCC 1A00836T = JCM 30155T). PMID:26374202

  14. Effects of Rhizobium inoculation on Trifolium resupinatum antioxidant system under sulfur dioxide pollution

    Ladan Bayat

    2014-01-01

    Full Text Available Introduction: Plant growth stimulating rhizobacteria are beneficial bacteria that can cause resistance to various stresses in plants. One of these stresses is SO2 air pollution. SO2 is known as a strong damaging air pollutant that limits growth of plants. The aim of this study is evaluation of the effects of bacterial inoculation with native and standard Rhizobium on Persian clover root growth and antioxidants activity and capacity under air SO2 pollution. Materials and methods: In this study, 31 days plants (no-inoculated and inoculated with two strains of Rhizobium exposed to the different concentrations of SO2 (0 as a control, 0.5, 1, 1.5 and 2 ppm for 5 consecutive days and 2 hours per day. Results: Results showed different concentrations of SO2 had a significant effect on Persian clover root weight and antioxidant system. Increasing SO2 stress decreased root fresh and dry weight and antioxidant capacities (IC50 and increased antioxidant activities (I% of Persian clover leaves significantly in comparison to the control plants (under 0 ppm and increased SOD, CAT and GPX activity. Inoculation of Persian clover plants with native and standard Rhizobium increased root weight and did not show a significant effect on antioxidants activity and capacity, but interaction between Rhizobium inoculation and SO2 treatment reduced significantly the stress effects of high concentration of SO2 on root growth and antioxidants activity and capacity. In fact, level of this change of root growth and antioxidant system under SO2 pollution stress in inoculated plants was lower than in the non-inoculated plants. Discussion and conclusion: As a result, an increase in SO2 concentration caused a decrease in root weight, increase in antioxidants activity and capacity of Persian clover. Inoculation with Rhizobium strains could alleviate the effect of SO2 pollution on antioxidant system by effects on root growth.

  15. Isolation and characterization of Azospirillum brasilense loci that correct Rhizobium meliloti exoB and exoC mutations.

    Michiels, K W; Vanderleyden, J.; Van Gool, A P; Signer, E R

    1988-01-01

    The occurrence in Azospirillum brasilense of genes that code for exopolysaccharide (EPS) synthesis was investigated through complementation studies of Rhizobium meliloti Exo- mutants. These mutants are deficient in the synthesis of the major acidic EPS of Rhizobium species and form empty, non-nitrogen-fixing root nodules on alfalfa (J. A. Leigh, E. R. Signer, and G. C. Walker, Proc. Natl. Acad. Sci. USA 82:6231-6235, 1985). We demonstrated that the exoC mutation of R. meliloti could be correc...

  16. Potensi Rhizobium dan Pupuk Nitrogen Untuk Meningkatkan Pertumbuhan dan Produksi Kedelai (Glycine max L) Pada Lahan Bekas Sawah

    Mayani, Nanda

    2012-01-01

    Nanda Mayani, 2012. "Potential Rhizobium and Nitrogen Fertilizer to Growth and Soybean Production (Glycine max L.) on the Former Rice Field". The research aims to determine the potential of Rhizobium on the former rice field to increase growth and soybean production. The research was conducted on the former rice field at Meunasah Alue Muara Dua Lhokseumawe, NAD province, from March until July 2011. The research method used was Randomized Block Design factorial pattern of two factors and th...

  17. Asymbiotic Acetylene Reduction by a Fast-Growing Cowpea Rhizobium Strain with Nitrogenase Structural Genes Located on a Symbiotic Plasmid

    Bender, Gregory L.; Plazinski, Jacek; Rolfe, Barry G.

    1986-01-01

    A procedure was designed which enabled the detection of ex planta nitrogenase activity in the fast-growing cowpea Rhizobium strain IHP100. Nitrogenase activity in agar culture under air occurred at a rate similar to that found for Bradyrhizobium strain CB756 but lower than that for Rhizobium strain ORS571. Hybridization studies showed that both nod and nif genes were located on a 410-kilobase Sym plasmid in strain IHP100.

  18. Complete Genome Sequence of the Sesbania Symbiont and Rice Growth-Promoting Endophyte Rhizobium sp. Strain IRBG74

    Crook, Matthew B.; Mitra, Shubhajit; Ané, Jean-Michel; Sadowsky, Michael J.; Gyaneshwar, Prasad

    2013-01-01

    Rhizobium sp. strain IRBG74 is the first known nitrogen-fixing symbiont in the Agrobacterium/Rhizobium clade that nodulates the aquatic legume Sesbania sp. and is also a growth-promoting endophyte of wetland rice. Here, we present the sequence of the IRBG74 genome, which is composed of a circular chromosome, a linear chromosome, and a symbiotic plasmid, pIRBG74a.

  19. Bouvard et Pécuchet et le désir amoureux

    Anne Herschberg Pierrot

    2010-09-01

    Full Text Available L’article propose une étude de genèse du chapitre 7 de Bouvard et Pécuchet, consacré à l’amour, qui forme une étape encyclopédique a priori un peu surprenante. Flaubert s’amuse à écrire ces aventures de Bouvard et Pécuchet, dans un pays qui n’est pas si tendre. L’étude de genèse porte sur le travail de l’écriture de plusieurs temps forts du chapitre (dans l’incipit, et les scènes de duos, notamment la scène entre Mme Castillon et Gorgu. Elle permet de montrer l’effacement de détails érotiques, mais aussi du politique et de l’histoire, qui se trouvent condensés dans le texte final. Elle révèle aussi le rôle concerté de ce chapitre dans la construction du roman et l’itinéraire des personnages. Anodin en apparence, ce chapitre est emblématique d’une poétique fondée sur l’ellipse, et qui mêle le jeu et le sérieux.This article presents a textual genetics study of Bouvard et Pécuchet’s 7th chapter, about love, which appears to be a surprising encyclopedic stage of the novel. Flaubert has fun writing these adventures in a not so tender country. This genetics study focuses on the writing of several key moments of the chapter (in the beginning and the duo scenes, such as the one between Mme Castillon and Gorgu. It reveals the erasure of erotic details, as well as politics and history, which end up condensed in the final text. It also shows this chapter’s concerted role in the construction of the novel and the characters’ development. Apparently minor, this chapter is emblematic of a poetics founded on the ellipsis, mingling play and seriousness.

  20. Rhizobium promotes non-legumes growth and quality in several production steps: towards a biofertilization of edible raw vegetables healthy for humans.

    García-Fraile, Paula; Carro, Lorena; Robledo, Marta; Ramírez-Bahena, Martha-Helena; Flores-Félix, José-David; Fernández, María Teresa; Mateos, Pedro F; Rivas, Raúl; Igual, José Mariano; Martínez-Molina, Eustoquio; Peix, Álvaro; Velázquez, Encarna

    2012-01-01

    The biofertilization of crops with plant-growth-promoting microorganisms is currently considered as a healthy alternative to chemical fertilization. However, only microorganisms safe for humans can be used as biofertilizers, particularly in vegetables that are raw consumed, in order to avoid sanitary problems derived from the presence of pathogenic bacteria in the final products. In the present work we showed that Rhizobium strains colonize the roots of tomato and pepper plants promoting their growth in different production stages increasing yield and quality of seedlings and fruits. Our results confirmed those obtained in cereals and alimentary oil producing plants extending the number of non-legumes susceptible to be biofertilized with rhizobia to those whose fruits are raw consumed. This is a relevant conclusion since safety of rhizobia for human health has been demonstrated after several decades of legume inoculation ensuring that they are optimal bacteria for biofertilization. PMID:22675441

  1. Combined subtraction hybridization and polymerase chain reaction amplification procedure for isolation of strain-specific Rhizobium DNA sequences.

    Bjourson, A J; Stone, C E; Cooper, J E

    1992-07-01

    A novel subtraction hybridization procedure, incorporating a combination of four separation strategies, was developed to isolate unique DNA sequences from a strain of Rhizobium leguminosarum bv. trifolii. Sau3A-digested DNA from this strain, i.e., the probe strain, was ligated to a linker and hybridized in solution with an excess of pooled subtracter DNA from seven other strains of the same biovar which had been restricted, ligated to a different, biotinylated, subtracter-specific linker, and amplified by polymerase chain reaction to incorporate dUTP. Subtracter DNA and subtracter-probe hybrids were removed by phenol-chloroform extraction of a streptavidin-biotin-DNA complex. NENSORB chromatography of the sequences remaining in the aqueous layer captured biotinylated subtracter DNA which may have escaped removal by phenol-chloroform treatment. Any traces of contaminating subtracter DNA were removed by digestion with uracil DNA glycosylase. Finally, remaining sequences were amplified by polymerase chain reaction with a probe strain-specific primer, labelled with 32P, and tested for specificity in dot blot hybridizations against total genomic target DNA from each strain in the subtracter pool. Two rounds of subtraction-amplification were sufficient to remove cross-hybridizing sequences and to give a probe which hybridized only with homologous target DNA. The method is applicable to the isolation of DNA and RNA sequences from both procaryotic and eucaryotic cells. PMID:1637166

  2. Chemical characterization of the gels produced by the diazotrophic bacteria Rhizobium tropici and Mesorhizobium sp; Caracterizacao quimica dos geis produzidos pelas bacterias diazotroficas Rhizobium tropici e Mesorhizobium sp.

    Monteiro, Nilson Kobori [Departamento de Engenharia e Tecnologia de Alimentos, Instituto de Biociencias, Letras e Ciencias Exatas, Universidade Estadual Paulista, Sao Jose do Rio Preto - SP (Brazil); Aranda-Selverio, Gabriel; Exposti, Diego Tadeu Degli; Silva, Maria de Lourdes Corradi da [Departamento de Fisica, Quimica e Biologia, Faculdade de Ciencias e Tecnologia, Universidade Estadual Paulista, Presidente Prudente - SP (Brazil); Lemos, Eliana Gertrudes Macedo; Campanharo, Joao Carlos [Departamento de Tecnologia, Faculdade de Ciencias Agrarias e Veterinaria, Universidade Estadual Paulista, Jaboticabal - SP (Brazil); Silveira, Joana Lea Meira [Departamento de Bioquimica e Biologia Molecular, Universidade Federal do Parana, Curitiba - PR (Brazil)

    2012-07-01

    The exopolysaccharides with characteristics of gel produced by Rhizobium tropici (EPSRT) and Mesorhizobium sp (EPSMR) are acidic heteropolysaccharide composed mainly of glucose and galactose in a molar ratio of 4:1 and 5:1 respectively, with traces of mannose ({approx} 1%). Chemical analysis showed the presence of uronic acid, pyruvate and acetyl-substituents in the structures of both polymers. Experiments of gel permeation chromatography and polyacrylamide gel electrophoresis showed that EPSRT and EPSMR are homogeneous molecules with low grade of polydispersity. The EPS were characterized using spectroscopic techniques of FT-IR, {sup 1}H and {sup 13}C-NMR. (author)

  3. Efficacy of Various Rhizobium Strains to Different Varieties of Groundnut (Arachis hypogea L.

    M. Aslam

    1999-01-01

    Full Text Available Groundnut variety BARD-699 produced significantly the most promising yield than that of variety BARI-89 at Attock, Fatehjang and NARC, Islamabad. Rhizobium strains, NC-92 was found to be less efficient as compared to TAL-1000; TAL-1371. Nodule dry mass and number of pods per plant were much higher than that of control treatment. Although a significant difference in growth and yield of both the varieties due to Rhizobium inoculation was observed but on average basis TAL-1000 and TAL-1371 gave significantly better response for both the varieties in improving growth and yield at all sites. Nevertheless, future prospects for groundnut production are good in Pakistan if the farmers are realized to practice inoculation technology in their fields.

  4. Genotypic Characterisation of Indigenous Rhizobium leguminosarum bv. viciae Field Population in Croatia

    Mihaela Blažinkov

    2007-06-01

    Full Text Available Genetic diversity of thirteen Rhizobium legumnosarum bv. viciae strains isolated from different field sites in continental part of Croatia was investigated. All rhizobial isolates were obtained either from plants grown in pots containing soil samples or from field grown plants. The strains were analyzed for DNA polymorphism using two DNA fingerprinting methods - randomly amplified polymorphic DNA (RAPD-PCR and repetitive extragenomic palindromic- PCR (rep-PCR. Both methods resulted in very similar grouping of strains. Cluster analysis of rep- and RAPD-PCR profi les showed significant differences among Rh. leguminosarum bv. viciae isolates. The highest differences were detected among reference strains and all field isolates revealing considerable genetic diversity of rhizobial field populations. These results suggest the presence of adapted indigenous Rhizobium leguminosarum bv. viciae strains, probably with higher competitive ability, whose symbiotic properties have to be evaluated in further investigations.

  5. Strain-specific fingerprints of Rhizobium galegae generated by PCR with arbitrary and repetitive primers.

    Selenska-Pobell, S; Gigova, L; Petrova, N

    1995-10-01

    Strain-specific genomic patterns of Rhizobium galegae were generated by PCR using both arbitrary and repetitive (BOX, ERIC and REP) primers. The identification of the strains was achieved also by RFLP analysis. However, the PCR genomic fingerprinting has significant advantages: it is not only simpler and faster, but it is also much more discriminative because it deals with the full bacterial genome and not only with parts of it as is the case with RFLP. In addition, both kinds of PCR fingerprinting (using arbitrary or repetitive primers) generated highly specific and reproducible patterns when parallel reactions with total bacterial DNA, extracted from independent liquid cultures were performed. The latter shows that AP- and rep-PCR are convenient for controlling the production and application of Rhizobium inoculants. PMID:7592135

  6. Isolation and properties of an ultraviolet-sensitive mutant of Rhizobium trifolii

    In an attempt to isolate a strain of Rhizobium trifolii which could be highly mutated by ultraviolet light (u.v.), a u.v.-sensitive mutant was isolated using a semi-selective procedure. The mutant was not only 85 times more sensitive than the wild-type to the lethal effects of u.v., but was mutated at u.v. doses which had little mutagenic effect on the wild-type. Its sensitivity to the mutagenic agents methyl methanesulphonate and gamma rays was unaltered, but its spontaneous mutation frequencies for two antibiotic resistances were increased. The mutation conferring u.v. sensitivity was mapped on the chromosome of Rhizobium leguminosarum 300 in a position between the markers ser-2 and ade-88. Unsuccessful attempts were made to transfer into the u.v.-sensitive mutant any one of a number of plasmids known to decrease the lethality of u.v. and enhance its mutagenicity. (author)

  7. Biocontrol of Fusarium Wilt by Bacillus Pumilus, Pseudomonas Alcaligenes and Rhizobium Sp. on Lentil

    Akhtar, Mohd Sayeed; SHAKEEL, Uzma; SIDDIQUI, Zaki Anwar

    2010-01-01

    The present study examined the effects of Bacillus pumilus, Pseudomonas alcaligenes, and Rhizobium sp. on wilt disease caused by Fusarium oxysporum f. sp. lentis and on the growth of lentil. Inoculation with F. oxysporum caused significant wilting, and reduced plant growth, the number of pods, and nodulation. Inoculation with B. pumilus together with P. alcaligenes caused a greater increase in plant growth, number of pods, nodulation, and root colonization by rhizobacteria, and also reduced F...

  8. Adaptation of Rhizobium leguminosarum to pea, alfalfa and sugar beet rhizospheres investigated by comparative transcriptomics

    Ramachandran, Vinoy K.; East, Alison K.; Karunakaran, Ramakrishnan; Downie, J.Allan; Poole, Philip S.

    2011-01-01

    Background The rhizosphere is the microbe-rich zone around plant roots and is a key determinant of the biosphere's productivity. Comparative transcriptomics was used to investigate general and plant-specific adaptations during rhizosphere colonization. Rhizobium leguminosarum biovar viciae was grown in the rhizospheres of pea (its legume nodulation host), alfalfa (a non-host legume) and sugar beet (non-legume). Gene expression data were compared to metabolic and transportome maps to unders...

  9. Industrial wastewater as raw material for exopolysaccharide production by Rhizobium leguminosarum

    Mohamed Sellami; Tomasz Oszako; Nabil Miled; Faouzi Ben Rebah

    2015-01-01

    The objective of this study was to evaluate the exopolysaccharide (EPS) production by Rhizobium leguminosarum cultivated in wastewater generated by oil companies (WWOC1 and WWOC2) and fish processing industry (WWFP). The results obtained in Erlenmeyer flasks indicated that the rhizobial strain grew well in industrial wastewater. Generally, wastewater composition affected the growth and the EPS production. WWFP allowed good bacterial growth similar to that obtained with the standard medium (YM...

  10. Isolation and characterization of a gene coding for a novel aspartate aminotransferase from Rhizobium meliloti.

    Alfano, J R; Kahn, M. L.

    1993-01-01

    Aspartate aminotransferase (AAT) is an important enzyme in aspartate catabolism and biosynthesis and, by converting tricarboxylic acid cycle intermediates to amino acids, AAT is also significant in linking carbon metabolism with nitrogen metabolism. To examine the role of AAT in symbiotic nitrogen fixation further, plasmids encoding three different aminotransferases from Rhizobium meliloti 104A14 were isolated by complementation of an Escherichia coli auxotroph that lacks three aminotransfera...

  11. Isolation and characterization of transposon Tn5-induced symbiotic mutants of Rhizobium loti.

    Chua, K Y; Pankhurst, C E; Macdonald, P E; Hopcroft, D H; Jarvis, B D; Scott, D.B.

    1985-01-01

    Rhizobium loti NZP2037 and NZP2213, each cured of its single large indigenous plasmid, formed effective nodules on Lotus spp., suggesting that the symbiotic genes are carried on the chromosome of these strains. By using pSUP1011 as a vector for introducing transposon Tn5 into R. loti NZP2037, symbiotic mutants blocked in hair curling (Hac), nodule initiation (Noi), bacterial release (Bar), and nitrogen fixation (Nif/Cof) on Lotus pedunculatus were isolated. Cosmids complementing the Hac, Noi,...

  12. Rhizobium symbiotic genes required for nodulation of legume and nonlegume hosts

    Marvel, Deborah J.; Torrey, John G.; Ausubel, Frederick M.

    1987-01-01

    Parasponia, a woody member of the elm family, is the only nonlegume genus whose members are known to form an effective nitrogen-fixing symbiosis with Bradyrhizobium or Rhizobium species. The Bradyrhizobium strain Rp501, isolated from Parasponia nodules, also nodulates the legumes siratro (Macroptilium atropurpureum) and cowpea (Vigna unguiculata). To test whether some of the same genes are involved in the early stages of legume and nonlegume nodulation, we generated transposon Tn5 insertions ...

  13. Rhizobium-Legume Symbiosis and Nitrogen Fixation under Severe Conditions and in an Arid Climate

    Zahran, Hamdi Hussein

    1999-01-01

    Biological N2 fixation represents the major source of N input in agricultural soils including those in arid regions. The major N2-fixing systems are the symbiotic systems, which can play a significant role in improving the fertility and productivity of low-N soils. The Rhizobium-legume symbioses have received most attention and have been examined extensively. The behavior of some N2-fixing systems under severe environmental conditions such as salt stress, drought stress, acidity, alkalinity, ...

  14. Genetic structure of natural populations of the nitrogen-fixing bacterium Rhizobium meliloti.

    Eardly, B D; Materon, L A; Smith, N H; Johnson, D. A.; Rumbaugh, M D; Selander, R K

    1990-01-01

    The genetic structure of populations of the symbiotic nitrogen-fixing soil bacterium Rhizobium meliloti was examined by analysis of electrophoretically demonstrable allelic variation in 14 metabolic, presumably chromosomal, enzyme genes. A total of 232 strains were examined, most of which were isolated from southwest Asia, where there is an unsurpassed number of indigenous host species for R. meliloti. The collection consisted of 115 isolates recovered from annual species of Medicago in Syria...

  15. Genetic diversity of an Italian Rhizobium meliloti population from different Medicago sativa varieties.

    D. Paffetti; Scotti, C; Gnocchi, S; Fancelli, S; Bazzicalupo, M

    1996-01-01

    We investigated the genetic diversity of 96 Rhizobium meliloti strains isolated from nodules of four Medicago sativa varieties from distinct geographic areas and planted in two different northern Italian soils. The 96 isolates, which were phenotypically indistinguishable, were analyzed for DNA polymorphism with the following three methods: (i) a randomly amplified polymorphic DNA (RAPD) method, (ii) a restriction fragment length polymorphism (RFLP) analysis of the 16S-23S ribosomal operon spa...

  16. Effect of Light and Organic Acids on Oxygen Uptake by BTAi 1, a Photosynthetic Rhizobium

    Wettlaufer, S. H.; Hardy, R. W. F.

    1992-01-01

    A photosynthetic rhizobium, strain BTAi 1, was cultured ex planta to investigate its photosynthetic-respiratory system and the response of this interactive system to light quantity and quality and to the addition of organic acids. Oxygen uptake, as measured with an oxygen electrode, is diminished upon illumination, with the amount of decrease related to light intensity. This oxygen-sparing effect is correlated with the wavelengths of light that are associated with bacteriochlorophyll absorban...

  17. Regulation and effects of the type-three secretion system of "Rhizobium" species NGR234

    Kambara, Kumiko; Broughton, William John; Deakin, William James

    2008-01-01

    "Rhizobium" sp. NGR234 establishes a symbiotic interaction with many legume plants. Regulatory cascade which is trigged by plant produced flavonoids is intricate and numerous factors participate including several transcriptional regulators to control the synthesis of Nod-factors, polysaccharides and T3SS. The striking effects of the NodV (sensor) and NodW (regulator) two-component system were observed on key symbiosis regulators of the regulatory cascade in the absence of flavonoids. The NodV...

  18. Rhizobium meliloti mutants deficient in phospholipid N-methyltransferase still contain phosphatidylcholine.

    de Rudder, K E; Thomas-Oates, J E; Geiger, O

    1997-01-01

    Phosphatidylcholine (PC) is the major membrane-forming phospholipid in eukaryotes. In addition to this structural function, PC is thought to play a major role in lipid turnover and signalling in eukaryotic systems. In prokaryotes, only some groups of bacteria, among them the members of the family Rhizobiaceae, contain PC. To understand the role of PC in bacteria, we have studied Rhizobium meliloti 1021, which is able to form nitrogen-fixing nodules on its legume host plants and therefore has ...

  19. Phytostimulatory effect of Rhizobium and Plant Growth Promoting Rhizobacteria in common bean (Phaseolus vulgaris L.) interaction

    Torres Gutiérrez, Roldán

    2008-01-01

    De symbiose tussen planten van de familie Leguminosae en sommige bacteriën wordt gekenmerkt door de vorming van nieuwe plantorganen, de zogenoemde nodules of wortelknolletjes, op de wortels of stengel. De cellen van deze nieuwe organen worden geïnfecteerd door de specifieke microsymbionten. De best gekende symbiotische bacteriën behoren tot de groep van de Rhizobiaceae met de genera Rhizobium, Bradyrhizobium, Sinorhizobium (Ensifer), Mesorhizobium, Azorhizobium, en Allorhizobium, collectief r...

  20. Role of Microniches in Protecting Introduced Rhizobium leguminosarum biovar trifolii against Competition and Predation in Soil

    Postma, J; Hok-A-Hin, C.H.; Veen, J.A. van

    1990-01-01

    The importance of microniches for the survival of introduced Rhizobium leguminosarum biovar trifolii cells was studied in sterilized and recolonized sterilized loamy sand and silt loam. The recolonized soils contained several species of soil microorganisms but were free of protozoa. Part of these soil samples was inoculated with the flagellate Bodo saltans, precultured on rhizobial cells. The introduced organisms were enumerated in different soil fractions by washing the soil, using a standar...

  1. Bacterial Growth Rates and Competition Affect Nodulation and Root Colonization by Rhizobium meliloti

    Li, De-Ming; Alexander, Martin

    1986-01-01

    The addition of streptomycin to nonsterile soil suppressed the numbers of bacterial cells in the rhizosphere of alfalfa (Medicago sativa L.) for several days, resulted in the enhanced growth of a streptomycin-resistant strain of Rhizobium meliloti, and increased the numbers of nodules on the alfalfa roots. A bacterial mixture inoculated into sterile soil inhibited the colonization of alfalfa roots by R. meliloti, caused a diminution in the number of nodules, and reduced plant growth. Enteroba...

  2. Competitive Abilities of Rhizobium meliloti Strains Considered to Have Potential as Inoculants

    van Rensburg, Henri Jansen; Strijdom, Barend W.

    1982-01-01

    Twenty four strains of Rhizobium meliloti considered to have potential for inoculant production were grouped in pairs and tested for their ability to compete for nodulation on Medicago sativa, Medicago truncatula, and Medicago littoralis. At the outset, each pair of strains, which consisted of a wild type and a selected streptomycin-resistant mutant of another strain, was tested in an autoclaved soil. Six strain pairs, each consisting of a good and a poor competitor, reacted consistently when...

  3. Influence of Azospirillum Strains on the Nodulation of Clovers by Rhizobium Strains

    Plazinski, Jacek; Rolfe, Barry G.

    1985-01-01

    Mixed cultures of several Azospirillum and Rhizobium trifolii strains caused either an inhibition or stimulation of nodule formation on plant hosts as compared with nodulation of plants inoculated with R. trifolii alone. Azospirillum strains affected the nodulation process at a precise cell ratio (R. trifolii/Azospirillum cells) and time of inoculation. All Azospirillum strains used showed a variation in their ability to inhibit or enhance nodulation by R. trifolii strains. When nonviable cel...

  4. Effect of salt stress and phosphorus deficiency in mutants of rhizobium obtained by gamma irradiation

    Two strains of Rhizobium: Rhizobium Tropici and Mesorhizobium Ciceri nodulating respectively common bean and chickpea were treated by gamma irradiation (60Co) source. Radiosensibility analysis showed that 800 Gy was the biggest dose supported by these two strains. We isolated gamma irradiated resistant strain in order to select mutant of them which can supported salt stress and phosphorus deficiency. Salinity analysis showed that Mesorhizobium Ciceri 835 strain, can tolerate up to 18g/l (273 mM NaCl) of salt, whereas, their irradiation mutants tolerate salinity up to 33g/l (564mM. NaCl) Rhizobium Tropici CIAT899 can survive at 20g/l (342 mM) either for control strain or mutants. Analysis of phosphorus deficiency showed that either Rhizobium Tropici CIAT899, or Mesorhizobium Ciceri 835 can survive in medium without phosphore. Our results permit us to screen mutants tolerant to these stresses wide spread in Mediterranean soil. In this study, we choose two mutants strains irradiated by 700Gy and two mutants irradiated by 800Gy in each species, these mutants were characterized by their best growth compared with their reference strains. Our results showed that Gamma irradiation modified antibiotic resistance, such as kanamicyne, tetracycline, vancomicyne, streptomicyne, penicilline, either at 700Gy or at 800Gy, we obtained significant modification of response and persistence of penicilline resistance. Biochemical analysis showed that these strains had a variable superoxide dismutase (SOD, E.C. 1.15.1.1) and catalase (CAT, E.C. 1.11.1.6) activities essentially in Mesorhizobium Ciceri 835 mutant strains, these two enzymatic antioxidants was suggested to play an important role in environmental stress tolerance. (author)

  5. Relationships between C4 dicarboxylic acid transport and chemotaxis in Rhizobium meliloti.

    Robinson, J.B.; Bauer, W D

    1993-01-01

    The relationship between chemotaxis and transport of C4 dicarboxylic acids was analyzed with Rhizobium meliloti dct mutants defective in one or all of the genes required for dicarboxylic acid transport. Succinate, malate, and fumarate were moderately potent chemoattractants for wild-type R. meliloti and appeared to share a common chemoreceptor. While dicarboxylate transport is inducible, taxis to succinate was shown to be constitutive. Mutations in the dctA and dctB genes both resulted in the...

  6. Biochemical Analysis of Chickpea Protection Against Fusarium Wilt Afforded by Two Rhizobium Isolates

    A. Arfaoui

    2005-01-01

    Full Text Available Germinated seeds of two chickpea cultivars ILC482 and INRAT87/1, respectively susceptible and moderately resistant to Fusarium oxysporum f. sp. ciceris (Foc, were preinoculated with a suspension of two Rhizobium isolates PchDMS and Pch43. Three days later, the seedlings were challenged by root dip with a conidial suspension of Foc race 0. The two Rhizobium isolates protected chickpea plants from F. oxysporum infection; the best protection has been obtained by PchDMS for the two cultivars. For the susceptible cultivar, mortality was 12.5 and 33.33% for treated plants, respectively with PchDMS and Pch43 as compared to the 79.16% in the inoculated control with Foc only. For the INRAT87/1 Cv. mortality was 8.33 and 12.5% for treated plants, respectively with PchDMS and Pch43 compared to the 54.16% in the control inoculated treatment. The two Rhizobium isolates stimulated the peroxidases and polyphenoloxidases activities and induced the accumulation of phenolic compounds. The maximum of peroxidases activities in plant roots were reached 24 h after challenging. However, the higher activity of polyphenoloxidases and the higher level of the phenolic compounds were recorded 72 h after Foc inoculation. Comparing the two strains, PchDMS was more effective in inducing enzymes and phenolic compounds and highest levels were recorded in INRAT87/1 cultivar.

  7. Role of Dual Inoculation of Rhizobium and Arbuscular Mycorrhizal (AM Fungi on Pulse Crops Production

    Erneste HAVUGIMANA

    2016-01-01

    Full Text Available Legume crops are useful as human and animal feed, wood energy, and as soil-improving components of agricultural and agro forestry systems through its association with bio-fertilizers. The later have a potential environment friendly inputs that are supplemented for proper plant growth. Bio-fertilizers are preparations containing living cells of microorganisms that help crop plants in the uptake of nutrients by their interactions in the rhizosphere. Arbuscular mycorrhizal (AM fungi are beneficial symbionts for plant growth. They are associated with higher plants by a symbiotic association and benefit plants in the uptake of phosphorus nutrients, production of growth hormones, increase of proteins, lipids and sugars levels, helps in heavy metal binding, salinity tolerance and disease resistance. In nature symbiotic association of Rhizobium and leguminous plants fixes atmospheric nitrogen. Indeed, research has proved that the association of mycorrhizae fungi and Rhizobium, with pulse crops, increased the beneficial aspects comparatively more than their single associations with the host plants. This review focuses on the role of dual inoculation of AM fungi and Rhizobium on different pulse crops.

  8. Genodiversity of dominant Rhizobium leguminosarum bv. Trifolii isolated from 11 types of soil in Serbia

    Joši? Dragana

    2008-01-01

    Full Text Available Rhizobium leguminosarum bv. trifolii is microsymbiont Trifolium pratense and Trifolium repens, which are very important legumes in Serbia. The natural nodulating population of those bacteria was collected and estimated biodiversity distribution by monitoring dominant genotypes of these bacteria. The population of Rhizobium leguminosarum bv. trifolii were collected from 50 marked locations of 11 types of soil in Serbia. 437 natural isolates, rescued from nodules of Trifolium repens or Trifolium pratense, were analyzed by phenotypic approach. We obtained 156 different isolates on the basis of differences in their IAR - intrinsic antibiotic resistance (five antibiotics and HMT- heavy methal tolerance (five heavy metals. We investigated 56 dominant isolates with more than three differences in IAR-HMT patterns by REP-PCR and RAPD fingerprinting (AP10 and SPH 1 primers. The results showed genodiversity of dominant Rhizobium leguminosarum bv. trifolii field isolates and offered the possibility to assess their changes on marked locations during time and under different environmental conditions and geographical distribution.

  9. Comparative effectiveness of different Rhizobium sp. for improving growth and yield of maize (Zea mays L.

    Ijaz Mehboob, Zahir Ahmad Zahir, Muhammad Arshad, Muhammad Khalid

    2012-05-01

    Full Text Available During the last couple of decades, it has been demonstrated that rhizobia can associate with roots of non-legumes also without forming true nodules, and can promote their growth by using one or more of the direct or indirect mechanisms of actions. This work examines the growth and yield responses of maize to inoculation with different species of rhizobia, isolated from the root nodules of chickpea (Cicer arietinum L., lentil (Lens culinaris M. and mung bean (Vigna radiata L. in pots and fields. Twenty isolates of rhizobia were isolated from root nodules each of mung bean, lentil and chickpea and were screened under axenic conditions. On the basis of their promising performance under axenic conditions, nine most efficient isolates (three from each legume host were selected, characterized and further evaluated for their growth promoting activities by conducting pot and field experiments. Results of pot experiment revealed that maximum increase in grain yield, 1000 grain weight, N, P and K uptake (up to 47.89, 54.52, 73.46, 84.66 and 59.19% by CRI28, respectively, over un-inoculated control was produced by the isolate of Mesorhizobium ciceri. Whereas, maximum improvement in rest of the parameters was caused by the isolates of Rhizobium phaseoli (i.e. fresh biomass, straw yield and root length up to 36.30% by A18, 25.46% by S6 and 81.89% by A18, respectively over un-inoculated control. Rhizobium leguminosarum isolates came out to be the least effective among the species tested. Similarly, all the selected isolates improved the growth and yield attributing parameters in fields as well but with varying capacity compared with un-inoculated control. The selected isolates of Mesorhizobium ciceri and Rhizobium phaseoli again remained superior compared to the isolates of Rhizobium leguminosarum under field conditions. The results of this study imply that rhizobium species had potential to promote growth and yield of maize but this technology should be employed after appropriate site specific investigations of particular rhizobial specie with respect to specific non-leguminous crop variety to get maximum benefit in terms of better growth and yield.

  10. Diversity of Rhizobium-Phaseolus vulgaris symbiosis: Overview and perspectives

    Common bean (Phaseolus vulgaris) has become a cosmopolitan crop, but was originally domesticated in the Americas and has been grown in Latin America for several thousand years. Consequently an enormous diversity of bean nodulating bacteria have developed and in the centers of origin the predominant species in bean nodules is R. etli. In some areas of Latin America, inoculation, which normally promotes nodulation and nitrogen fixation is hampered by the prevalence of native strains. Many other species in addition to R. etli have been found in bean nodules in regions where bean has been introduced. Some of these species such as R. leguminosarum bv. phaseoli, R. gallicum bv. phaseoli and R. giardinii bv. phaseoli might have arisen by acquiring the phaseoli plasmid from R. etli. Others, like R. trap id, are well adapted to acid soils and high temperatures and are good inoculants for bean under these conditions. The large number of rhizobia species capable of nodulating bean supports that bean is a promiscuous host and a diversity of bean-rhizobia interactions exists. Large ranges of dinitrogen fixing capabilities have been documented among bean cultivars and commercial beans have the lowest values among legume crops. Knowledge on bean symbiosis is still incipient but could help to improve bean biological nitrogen fixation. (author)

  11. Evaluation of Bean (Phaseolus vulgaris Seeds Inoculation with Rhizobium phaseoli and Plant Growth Promoting Rhizobacteria on Yield and Yield Components

    M. Yadegari

    2008-01-01

    Full Text Available To study the effect of co-inoculation with plant growth-promoting rhizobacteria (PGPR and Rhizobium, on yield and yield components of common bean (Phaseolus vulgaris L. cultivars was investigated in 2 consecutive years under field condition of plant growing evidence indicates that soil beneficial bacteria can positively affect symbiotic performance of rhizobia. PGPR strains Pseudomonas fluorescens P-93 and Azospirillum lipoferum S-21 as well as two highly effective Rhizobium strains were used in this study. Common bean seeds of three cultivars were inoculated with Rhizobium singly or in a combination with PGPR to evaluate their effect on growth characters. A significant variation of plant growth in response to inoculation with Rhizobium strains was observed. Treatment with PGPR significantly increased pod per plant, number of seeds per pod, weight of 100 seed, weight of seeds per plant, weight of pods per plant, total dry matter in R6 as well as seed yield and protein content. Co-inoculation with Rhizobium and PGPR demonstrated a significant increase in the yield and yield components. The results showed that all treatments of bacteria increased yield; however, strains Rb-133 with Pseudomonas fluorescens P-93 gave the highest seed yield, number of pods per plant, weight of 100 seed, seed protein yield, number seed per pod, seed protein yield.

  12. Colonization and Nitrogenase Activity of Triticum aestivum (cv. Baccross and Mahdavi to the Dual Inoculation with Azospirillum brasilense and Rhizobium meliloti plus 2,4-D

    Askary Mehry

    2008-01-01

    Full Text Available The potential enhancement of root colonization and nitrogenase activity of wheat cultivars (Baccross and Mahdavi was studied with application of two Azospirillum brasilense strains (native and Sp7 co-inoculated with two Rhizobium meliloti strains (native and DSMZ 30135. The results indicated that the colonization was different due to the strains and cultivars of wheat were used. Native A. brasilense colonized wheat root better than Sp7 strain. However, Baccross cv. reacted better with native Azospirillum compared to Mahdavi cv. which reacted better with Sp7. When plants inoculated with dual inoculants (SP7 with standard Rhizobium, the colonization of Azospirillum were increased significantly (from 1.67x105 to 22x105 cfu g-1 FW for Baccras cv. and 3.67x105 to 26x105 cfu g-1 FW for Mahdavi cultivar. When the standard Rhizobium as co-inoculants changed to the native Rhizobium, the colonization of Azospirillum was higher when compared to the single inoculants but was almost the same when compared to the standard Rhizobium. When the standard or native strains of Rhizobium used as single inoculation of wheat roots, the number of Rhizobium in the wheat roots were not changed significantly. However, when plants co-inoculated with Rhizobium and Azospirillum, the colonization of Rhizobium was increased. Co-inoculation of standard strain of R. melilot with A. brasilense Sp7 showed that the colonization of Rhizobium were increased from 0.67x105 to 21x105 cfu g-1 FW for Baccross cv. and 0.33x105 to 18x105 cfu g-1 FW for Mahdavi cv. This behavior was the same when inoculation of Rhizobium was happened with the native one. In dual inoculation, the highest nitrogenase activity was measured in combination of the local strains (native A. brasilense with the native R. meliloti and the lower one belongs to the combination of standard strains (Sp7 with standard R. meliloti. The difference in nirtogenase activity for different cultivars of wheat with Sp7 and standard Rhizobium is not significant but the difference for Sp7 strain plus native Rhizobium is significant (p>0.05. However, the differences were not significant (p<0.05 for nitrogenase activity in bacterial tubes, the difference for nitrogenase activity of co-inoculated plants with combination of Sp7 and Rhizobium either standard or native were significantly different

  13. The role of vesicular-arbuscular mycorrhiza in N2-fixed by legume-Rhizobium systems in phosphate-fixing agricultural soils

    The scarcity of available phosphate in many soils is a critical limiting factor in legume-Rhizobium-systems because it affects not only plant growth but nodulation and N2-fixation by the micro-symbiont. Hence, VA mycorrhizas, which are widespread in legumes, play an important role in the development of such crops and are thus of great interest for food production in the biosphere. This paper discusses the work developed in this laboratory in relation to the significance of VA mycorrhiza in N2-fixation within two legume-Rhizobium-systems: Medicago sativa (alfalfa)-Rhizobium meliloti and Hedysarum coronarium (sulla)-Rhizobium sp.. Several experiments have been carried out to study the interactions between natural and introduced VA endophytes and Rhizobium, and soluble phosphate fertilizer on growth, nodulation and N-uptake of the two test legumes in natural (unsterilized) agricultural soils. The tests were conducted under both pot and field conditions. (author)

  14. Effect of Rhizobium inoculation on some characters of a high protein mutant and its parent field bean Vicia faba L

    M1011 is a high protein mutant originally selected from the Egyptian bean (Vicia faba L.) variety Giza2 (G2) after seven generations of treating seeds with 4kR of 60Co gamma rays. Both the mutant line M1011 and its parent variety G2 were planted in soil inoculated with Rhizobium phaseoli after being sterilized. The plant and yield characters of both were then investigated. Results showed that the mean values of plant height, total and fertile number of branches per plant, number of pods per plant, seed yield and seed protein content increased significantly in both M1011 and G2 due to pre-sowing Rhizobium inoculation. Significant earliness in flowering and an increase in the number of seeds per pod were also noticed in M1011 after Rhizobium treatment. Therefore, the mutant line showed higher efficiency in utilizing bacterially fixed nitrogen than its parent mother variety Giza2. (author)

  15. Influence of a carbamate pesticide on growth, respiration (14C)-carbon metabolism and symbiosis of a Rhizobium sp

    Addition of aldicarb (2 methyl-2(methyl thio) propionaldehyde-O-methyl carbamoyl oxime) in the growth medium enhanced the growth of Rhizobium sp. (cowpea group) at 2ppm level while an inhibition was observed at the normal (5 ppm) and higher (10 ppm) concentrations. Respiration of the cells was also inhibited by 5 and 10 ppm levels of the chemical eventhough a stimulation was observed at 2 ppm (lower) concentration. The insecticide, when incorporated at 5 and 10 ppm levels in the medium increased the 14C-glucose incorporation and considerably altered the assimilation of the radioactive carbon in different fractions of rhizobium cells. Soil application of this insecticide (Temik 10 G) reduced the number of nodules formed and the total nitrogen content in cowpea plants inoculated with the Rhizobium sp. but enhanced the dry matter production of cowpea plants. (Auth.)

  16. GAT 3 - fuel cells and their management (PACoGES). Progress report; GAT 3 - piles a combustible et leur gestion (PACoGES). Rapport final (juillet 2002 a juin 2004)

    Lamy, C.

    2005-07-01

    The Topic Analysis Group PACoGES ('Piles a Combustible et leur Gestion') has conducted thoughts on fuel cells and their management with all the searchers concern with researches and developments on fuel cells and in particular on solid oxide fuel cells (SOFC, ITSOFC) running at high temperature (600 to 1000 C). This has concerned about 200 searchers working in about fifty laboratories (CNRS, CEA, EDF, GDF, INRETS, CNAM, Armines, and several industrial teams). Here is given the final report 2002-2004 concerning all the researches carried out by this Group. (O.M.)

  17. The conjugative plasmid of a bean-nodulating Sinorhizobium fredii strain is assembled from sequences of two Rhizobium plasmids and the chromosome of a Sinorhizobium strain

    Brom Susana

    2011-06-01

    Full Text Available Abstract Background Bean-nodulating Rhizobium etli originated in Mesoamerica, while soybean-nodulating Sinorhizobium fredii evolved in East Asia. S. fredii strains, such as GR64, have been isolated from bean nodules in Spain, suggesting the occurrence of conjugative transfer events between introduced and native strains. In R. etli CFN42, transfer of the symbiotic plasmid (pRet42d requires cointegration with the endogenous self-transmissible plasmid pRet42a. Aiming at further understanding the generation of diversity among bean nodulating strains, we analyzed the plasmids of S. fredii GR64: pSfr64a and pSfr64b (symbiotic plasmid. Results The conjugative transfer of the plasmids of strain GR64 was analyzed. Plasmid pSfr64a was self-transmissible, and required for transfer of the symbiotic plasmid. We sequenced pSfr64a, finding 166 ORFs. pSfr64a showed three large segments of different evolutionary origins; the first one presented 38 ORFs that were highly similar to genes located on the chromosome of Sinorhizobium strain NGR234; the second one harbored 51 ORFs with highest similarity to genes from pRet42d, including the replication, but not the symbiosis genes. Accordingly, pSfr64a was incompatible with the R. etli CFN42 symbiotic plasmid, but did not contribute to symbiosis. The third segment contained 36 ORFs with highest similarity to genes localized on pRet42a, 20 of them involved in conjugative transfer. Plasmid pRet42a was unable to substitute pSfr64a for induction of pSym transfer, and its own transfer was significantly diminished in GR64 background. The symbiotic plasmid pSfr64b was found to differ from typical R. etli symbiotic plasmids. Conclusions S. fredii GR64 contains a chimeric transmissible plasmid, with segments from two R. etli plasmids and a S. fredii chromosome, and a symbiotic plasmid different from the one usually found in R. etli bv phaseoli. We infer that these plasmids originated through the transfer of a symbiotic-conjugative-plasmid cointegrate from R. etli to a S. fredii strain, and at least two recombination events among the R. etli plasmids and the S. fredii genome. As in R. etli CFN42, the S. fredii GR64 transmissible plasmid is required for the conjugative transfer of the symbiotic plasmid. In spite of the similarity in the conjugation related genes, the transfer process of these plasmids shows a host-specific behaviour.

  18. Isolation, characterization, and complementation of Rhizobium meliloti 104A14 mutants that lack glutamine synthetase II activity.

    Somerville, J. E.; Shatters, R.G.; Kahn, M. L.

    1989-01-01

    The glutamine synthetase (GS)-glutamate synthase pathway is the primary route used by members of the family Rhizobiaceae to assimilate ammonia. Two forms of glutamine synthetase, GSI and GSII, are found in Rhizobium and Bradyrhizobium species. These are encoded by the glnA and glnII genes, respectively. Starting with a Rhizobium meliloti glnA mutant as the parent strain, we isolated mutants unable to grow on minimal medium with ammonia as the sole nitrogen source. For two auxotrophs that lack...

  19. Isotopic discrimination of nitrogen associated with biological nitrogen fixation on the system Rhizobium versus beans (Phaseolus vulgaris L.)

    Two experiments were carried out in the greenhouse using a complete randomized experimental design. The first experiments was designed to assess the effect of three bean cultivars, inoculated with a mixture of efficient Rhizobium strains on the isotopic N discrimination at four development stages of beans plants. The second experiment was carried out to verify if there is any discrimination caused by the Rhizobium strains used. The plants of both experiments were grown in a N free medium, with 5 replicates. At the harvesting, δN-15% was determined in the following parts of the bean plants: nodules, roots, shoots, cotyledons and pods. (author)

  20. Effects of Heavy Metal from Polluted Soils on the Rhizobium Diversity

    Vasilica STAN

    2011-05-01

    Full Text Available Heavy metals adversely influence microorganisms, affecting their growth, abundance, genetic diversity, nodulation ability and efficacy. The aim of this study was to isolate and characterize free-leaving Rhizobium from soil which were artificially polluted with Cu (100, 250, and 500 mg kg-1 soil, Zn (300, 700, and 1500 mg kg-1 soil and Pb (50, 250, and 1000 mg kg-1 soil, but also with a mixture of all these metals, and cultivated with red clover (Trifolium pratense L., and to compare them with bacteria isolated from similar type of soil, but unpolluted. Rhizobia from soil were isolated on YMA medium with or without bromothymol blue (0.00125% as a pH-change indicator and the morpho-physiological characteristics of the colonies were examined. The number of Rhizobium was estimated using the most probable number method. Compared to the control, a decrease of rhizobia number and an increase of the metal concentration were observed. Several decameric primers (Operon Technology type were used and a reduced polymorphism among isolated bacteria was observed. Moreover, significant differences were observed among these strains and the collection strains used as reference. Also, when primers nodCF/nodCI for detection of nod genes were used, several amplicons were obtained, different from the results obtained with similar strains isolated from unpolluted soil. These results suggest that the survival „price” of the Rhizobium in such polluted area was the alteration of some genes, including those involved in symbiosis and, probably, in nitrogen fixation.

  1. 75 FR 62858 - United States, et al.

    2010-10-13

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF JUSTICE Antitrust Division United States, et al. v. American Express Company, et al.; Proposed Final Judgment and... of America, et al. v. American Express Company, et al., Civil Action No. CV-10-4496. On October...

  2. 76 FR 38700 - United States, et al.

    2011-07-01

    ... published in the Federal Register on October 13, 2010 (75 FR 62858); and (3) published summaries of the... Antitrust Division United States, et al. v. American Express Company, et al.; Public Comments and Response... Final Judgment in United States, et al. v. American Express Company, et al., Civil Action No....

  3. Isolation and characterization of the recA gene of Rhizobium meliloti.

    Better, M; Helinski, D. R.

    1983-01-01

    Interspecific complementation of an Escherichia coli recA mutant with plasmids containing a gene bank of Rhizobium meliloti DNA was used to identify a clone which contains the recA gene of R. meliloti. The R. meliloti recA protein can function in recombination and in response to DNA damage when expressed in an E. coli recA host, and hybridization studies have shown that DNA sequence homology exists between the recA gene of E. coli and that of R. meliloti. The isolated R. meliloti recA DNA was...

  4. Isolation and characterization of an R-prime plasmid from Rhizobium meliloti.

    Kiss, G.B.; Dobo, K; Dusha, I; Breznovits, A; Orosz, L.; Vincze, E; Kondorosi, A

    1980-01-01

    Using a simple enrichment procedure, we isolated an R-prime derivative of plasmid R68.45 carrying a 17.8-megadalton segment of the Rhizobium meliloti 41 chromosome. The chromosomal segment carried on this plasmid (pGY1) includes the markers cys-24+, cys-46+, and att16-3. Plasmid pGY1 mobilized the chromosome in a polarized way starting from the region of homology, but cannot promote chromosome transfer from other sites. The att16-3 site on pGY1 allowed the integration of phage 16-3 into pGY1,...

  5. Isolation and characterization of ropA homologous genes from Rhizobium leguminosarum biovars viciae and trifolii.

    Roest, H P; Bloemendaal, C J; Wijffelman, C. A.; Lugtenberg, B J

    1995-01-01

    ropA encodes a 36-kDa outer membrane protein of Rhizobium leguminosarum bv. viciae strain 248 which constitutes the low-M(r) part of antigen group III (R.A. de Maagd, I.H.M. Mulders, H.C.J. Canter Cremers, B.J.J. Lugtenberg, J. Bacteriol. 174:214-221, 1992). We observed that genes homologous to ropA are present in strain 248 as well as in other R. leguminosarum strains, and we describe the cloning and characterization of two of these genes. Sequencing of a 2.2-kb Bg/II fragment from R. legumi...

  6. Low molecular weight EPS II of Rhizobium meliloti allows nodule invasion in Medicago sativa.

    González, J E; Reuhs, B.L.; Walker, G. C.

    1996-01-01

    Effective invasion of alfalfa by Rhizobium meliloti Rm1021 normally requires the presence of succinoglycan, an exopolysaccharide (EPS) produced by the bacterium. However, Rm1021 has the ability to produce a second EPS (EPS II) that can suppress the symbiotic defects of succinoglycan-deficient strains. EPS II is a polymer of modified glucose-(beta-1,3)-galactose subunits and is produced by Rm1021 derivatives carrying either an expR101 or mucR mutation. If the ability to synthesize succinoglyca...

  7. Maintenance of Intracellular pH and Acid Tolerance in Rhizobium meliloti

    O'Hara, Graham W.; Goss, Thomas J.; Dilworth, Michael J.; Glenn, Andrew R.

    1989-01-01

    The development and function of the Rhizobium meliloti-Medicago sp. symbiosis are sensitive to soil acidity. Physiological criteria that can be measured in culture which serve to predict acid tolerance in soil would be valuable. The intracellular pH of R. meliloti was measured using either radioactively labeled weak acids (5,5-dimethyloxazolidine-2,4-dione and butyric acid) or pH-sensitive fluorescent compounds; both methods gave similar values. Six acid-tolerant strains (WSM419, WSM533, WSM5...

  8. Extracción de adn plasmidico de cepas de rhizobium leguminosarum

    M. Y, Cortés L.; F. J. Vargas P.; J. E. Pinilla C.; G. Pérez G.; De Navarro, Y. N.

    2010-01-01

    S.e realizó una comparación simultánea de cuatro métodos para la extracción de ADN plasmídico. De los resultados experimentales se concluyó que únicamente con la técnica de Kronstad, en las condiciones ensayadas y con cultivos de cepas de Rhizobium leguminosarum bv Viceae en fase de crecimiento logarítmica temprana, se visualizaron 3 plásmidos para la cepa SEMIA 335 y un plásmido para la cepa B.

  9. Involvement of cytochromes and a flavoprotein in hydrogen oxidation in Rhizobium japonicum bacteroids.

    O'Brian, M R; Maier, R. J.

    1983-01-01

    Electron transport components involved in H2 oxidation were studied in membranes from Rhizobium japonicum bacteroids. Hydrogen oxidation in membranes was inhibited by antimycin A and 2-n-heptyl-4-hydroxyquinoline-N-oxide with Ki values of 39.4 and 5.6 microM, respectively. The inhibition of H2 uptake by cyanide was triphasic with Ki values of 0.8, 9.9, and 93.6 microM. This result suggested that three cyanide-reactive components were involved in H2 oxidation. H2-reduced minus O2-oxidized abso...

  10. Electron transport components involved in hydrogen oxidation in free-living Rhizobium japonicum.

    O'Brian, M R; Maier, R. J.

    1982-01-01

    Membranes from free-living Rhizobium japonicum were isolated to study electron transport components involved in H2 oxidation. The H2/O2 uptake rate ratio in membranes was approximately 2. The electron transport inhibitors antimycin A, cyanide, azide, hydroxylamine, and 2-n-heptyl-4-hydroxyquinoline-N-oxide (HQNO) inhibited H2 uptake and H2-dependent O2 uptake significantly. H2-reduced minus O2-oxidized absorption difference spectra revealed peaks at 551.5, 560, and 603 nm, indicating the invo...

  11. CONFIRMING LOCATION OF NITROGEN FIXING GENES ON PLASMIDS IN RHIZOBIUM ISOLATED FROM PISUM SATIVUM

    Balaji Hajare and Avinash Ade1

    2012-06-01

    Full Text Available To confirm the location of the nitrogen fixing genes whether on the plasmids or on the genomic DNA the Rhizobial isolates isolated from pea (Pisum sativum were treated with acridine orange with various concentrations and fixed nitrogen was estimated from the media in which these rhizobia were grown. There was no significant difference in between the cured and non cured strains of the Rhizobium which proved that the nitrogen fixing genes are not plasmid borne but these are located on the genomic DNA.

  12. Influence of Phosphate on the Growth and Nodulation Characteristics of Rhizobium trifolii†

    Leung, Kamtin; Bottomley, Peter J.

    1987-01-01

    The growth and nodulating characteristics of Rhizobium trifolii 6 and 36 differed under different external phosphate conditions. Under growth conditions designed to deplete the internal phosphate content of the rhizobia, strain 6 maintained a generation time of 5 h during the exponential phase over two cycles of growth in phosphate-depleted medium. In contrast, the generation time of strain 36 was extended from 3.5 to 9.8 h over two cycles of phosphate-depleted growth, although the organism e...

  13. Rhizobium meliloti produces a family of sulfated lipooligosaccharides exhibiting different degrees of plant host specificity.

    Schultze, M.; Quiclet-Sire, B; Kondorosi, E.; Virelizer, H; Glushka, J.N.; Endre, G; Géro, S D; Kondorosi, A

    1992-01-01

    We have shown that a Rhizobium meliloti strain overexpressing nodulation genes excreted high amounts of a family of N-acylated and 6-O-sulfated N-acetyl-beta-1,4-D-glucosamine penta-, tetra-, and trisaccharide Nod factors. Either a C(16:2) or a C(16:3) acyl chain is attached to the nonreducing end subunit, whereas the sulfate group is bound to the reducing glucosamine. One of the tetrasaccharides is identical to the previously described NodRm-1 factor. The two pentasaccharides as well as NodR...

  14. Production of Rhizobium Inoculants for Lupinus nootkatensis on Nutrient-Supplemented Pumice

    Einarsson, Sigurbjorn; Gudmundsson, Jon; Sverrisson, Halldor; Kristjansson, Jakob K.; Runolfsson, Sveinn

    1993-01-01

    The use of the legume Lupinus nootkatensis as a pioneer plant to fight soil erosion and to reclaim eroded soils in Iceland has been under development for a few years. Production of a robust, low-cost bacterial inoculant was therefore a prerequisite for the extended use of this plant. Volcanic pumice is a naturally expanded mineral which is available in vast amounts in Iceland. It was tested as a carrier for solid fermentation of Rhizobium lupini. Nutrient-supplemented pumice containing a smal...

  15. Effects of microgravity on the binding of acetylsalicylic acid by Rhizobium leguminosarum bv. trifolii

    Urban, James E.; Gerren, Richard; Zoelle, Jeffery

    1995-07-01

    Bacteroids can be induced in vitro by treating growing Rhizobium leguminosarum bv. trifolii with succinic acid or succinic acid structural analogs like acetylsalicylic acid. Quantitating bacteroid induction by measuring acetylsalicylic binding under normal (1 g) conditions showed two forms of binding to occur. In one form of binding cells immediately bound comparatively high levels of acetylsalicylic acid, but the binding was quickly reversed. The second form of binding increased with time by first-order kinetics, and reached saturation in 40 s. Similar experiments performed in the microgravity environment aboard the NASA 930 aircraft showed only one form of binding and total acetylsalicylic acid bound was 32% higher than at 1 g.

  16. Chemical characterization of the gels produced by the diazotrophic bacteria Rhizobium tropici and Mesorhizobium sp

    The exopolysaccharides with characteristics of gel produced by Rhizobium tropici (EPSRT) and Mesorhizobium sp (EPSMR) are acidic heteropolysaccharide composed mainly of glucose and galactose in a molar ratio of 4:1 and 5:1 respectively, with traces of mannose (∼ 1%). Chemical analysis showed the presence of uronic acid, pyruvate and acetyl-substituents in the structures of both polymers. Experiments of gel permeation chromatography and polyacrylamide gel electrophoresis showed that EPSRT and EPSMR are homogeneous molecules with low grade of polydispersity. The EPS were characterized using spectroscopic techniques of FT-IR, 1H and 13C-NMR. (author)

  17. Mutagenesis in pea (Pisum sativum L.) as a tool for studying plant Rhizobium symbiosis

    Pea mutants for symbiotic characteristics were obtained by treating seeds with ethylmethanesulphonate. They consisted of 15 mutants with no nodules (nod-), 10 mutants with inefficient nodules (nod+fix-) and four hypernodulating mutants (nod++nts) that also express a nitrate tolerant character of nodulation and fixation; 6, 7 and 1 loci, respectively, were identified. Strain specificity was found between a (nod+fix-) mutant and two Rhizobium leguminosarum strains. These isogenic mutants were also used in an agronomic study of nitrogen nutrition and in a cytological study to determine the stage at which abortion of symbiosis occurs. (author). 16 refs

  18. Mythe et pouvoir

    Alejandro Ruidrejo

    2013-07-01

    Full Text Available Si le mythe évoque en nous un monde idéal, le pouvoir nous rappel l’existence d’un monde bien réel. La tension ainsi créée est du même ordre que celle liée à la pensée sauvage et la pensée rationnelle. Le pouvoir, dans toutes ses manifestations et ses degrés dont le politique, a été toujours exploré par une pensée organisée, rationnellement construite, et ce type de pensée a été pendant trois siècles la structure des destins de nos sociétés. Les rêves collectifs bien que tenus en compte, n’entraient nullement dans les analyses finales d’une société et de son devenir. En effet tout ce qui tient de “l’irrationnel” restait à côté et aujourd’hui encore sont comptés ceux qui osent s’introduir dans une telle démarche. A la lecture de ces contributions, plusieurs questions surgissent. Il convient de se demander sous quelles configurations se composent les relations entre les deux termes mythe et pouvoir aujourd’hui. Quels sont les mythes du pouvoir à partir desquels se produit l’obéissance ? Mais aussi sous quelles formes a lieu l’invention des mythes qu’ attaquent ce qui est établit, ce qui est tolérable? Et plus encore, sous quel type de déplacement de sens, de chevauchement, se tisse la trame entre les mythes et les pouvoirs soutenant les images du monde qui gouvernent nos existences? De même pour la littérature et l’art en général, il faut questionner ce lien ténu par les artistes et les écrivains avec la société qui les porte , lien parfois dénié ou conflictuel.

  19. Sobrevivência e nodulação do Rhizobium tropici em sementes de feijão tratadas com fungicidas

    Araújo Ademir Sérgio Ferreira; Araújo Ricardo Silva

    2006-01-01

    O objetivo deste trabalho foi avaliar a sobrevivência e a capacidade de nodulação do Rhizobium tropici em sementes de feijão tratadas com fungicidas. O estudo foi realizado em laboratório e em casa de vegetação. Sementes de feijão (Phaseolus vulgaris) foram tratadas com seis diferentes fungicidas e inoculadas com Rhizobium tropici estirpe CIAT 899. A sobrevivência do Rhizobium nas sementes foi avaliada no tempo 0 e 24 horas após o tratamento com fungicidas e a inoculação, utilizando o método ...

  20. Isolation and characterization of an early colonizing Rhizobium sp. R8 from a household toilet bowl.

    Fukano, Toru; Gomi, Mitsuhiro; Osaki, Yukihiko; Morikawa, Masaaki

    2015-01-01

    The bacterial community structure was compared between the third days', one week', and three weeks' biofilm samples from the surface of a household toilet bowl. It was found that the PCR-DGGE band pattern of 16S rRNA gene was dramatically changed after the third day and was not further changed until three weeks. This result suggests that there are early and late colonizing bacterial groups. One of the early colonizers isolated from the third days' sample was Rhizobium sp. R8, a closest relative to Rhizobium giardinii, which exhibited the highest biofilm formation activity in an artificial urine condition. R8 produced extracellular polysaccharides containing galactose, glucose, and mannose at the molar ratio of 8:1:1, which were probably responsible for the biofilm formation. Its excelled biofilm formation and urease activities together with the lack of nodulation and nitrogen fixing genes in R8 suggest that this strain has been specifically adapted to urine condition in a toilet bowl. PMID:25707633

  1. A novel polar surface polysaccharide from Rhizobium leguminosarum binds host plant lectin.

    Laus, Marc C; Logman, Trudy J; Lamers, Gerda E; Van Brussel, Anton A N; Carlson, Russell W; Kijne, Jan W

    2006-03-01

    Rhizobium bacteria produce different surface polysaccharides which are either secreted in the growth medium or contribute to a capsule surrounding the cell. Here, we describe isolation and partial characterization of a novel high molecular weight surface polysaccharide from a strain of Rhizobium leguminosarum that nodulates Pisum sativum (pea) and Vicia sativa (vetch) roots. Carbohydrate analysis showed that the polysaccharide consists for 95% of mannose and glucose, with minor amounts of galactose and rhamnose. Lectin precipitation analysis revealed high binding affinity of pea and vetch lectin for this polysaccharide, in contrast to the other known capsular and extracellular polysaccharides of this strain. Expression of the polysaccharide was independent of the presence of a Sym plasmid or the nod gene inducer naringenin. Incubation of R. leguminosarum with labelled pea lectin showed that this polysaccharide is exclusively localized on one of the poles of the bacterial cell. Vetch roots incubated with rhizobia and labelled pea lectin revealed that this bacterial pole is involved in attachment to the root surface. A mutant strain deficient in the production of this polysaccharide was impaired in attachment and root hair infection under slightly acidic conditions, in contrast to the situation at slightly alkaline conditions. Our data are consistent with the hypothesis that rhizobia can use (at least) two mechanisms for docking at the root surface, with use of a lectin-glycan mechanism under slightly acidic conditions. PMID:16553877

  2. Revegetating fly ash landfills with Prosopis juliflora L.: impact of different amendments and Rhizobium inoculation.

    Rai, U N; Pandey, K; Sinha, S; Singh, A; Saxena, R; Gupta, D K

    2004-05-01

    A revegetation trial was conducted to evaluate the feasibility of growing a legume species, Prosopis juliflora L., on fly ash ameliorated with combination of various organic amendments, blue-green algal biofertilizer and Rhizobium inoculation. Significant enhancements in plant biomass, photosynthetic pigments, protein content and in vivo nitrate reductase activity were found in the plants grown on ameliorated fly ash in comparison to the plants growing in unamended fly ash or garden soil. Higher growth was obtained in fly ash amended with blue-green algae (BGA) than farmyard manure or press mud (PM), a waste from sugar-processing industry, due to the greater contribution of plant nutrients, supply of fixed nitrogen and increased availability of phosphorus. Nodulation was suppressed in different amendments of fly ash with soil in a concentration-duration-dependent manner, but not with other amendments. Plants accumulated higher amounts of Fe, Mn, Cu, Zn and Cr in various fly ash amendments than in garden soil. Further, inoculation of the plant with a fly ash tolerant Rhizobium strain conferred tolerance for the plant to grow under fly ash stress conditions with more translocation of metals to the above ground parts. The results showed the potential of P. juliflora to grow in plantations on fly ash landfills and to reduce the metal contents of fly ash by bioaccumulation in its tissues. PMID:14987858

  3. Release of Rhizobium spp. from Tropical Soils and Recovery for Immunofluorescence Enumeration.

    Kingsley, M T; Bohlool, B B

    1981-08-01

    Limitations associated with immunofluorescence enumeration of bacteria in soil derive largely from the efficiency with which cells can be separated from soil particles and collected on membrane filters for staining. Many tropical soils fix added bacteria tightly, resulting in low recoveries. Eight soils, representative of three of the major soil orders found in the tropics (oxisols, vertisols, and inceptisols), were tested for recovery of added Rhizobium strains. All except one Hawaiian andept (Typic Eutrandept) yielded recoveries ranging from 90 to oxisol. The results showed a close agreement with viable counts at different stages during the growth cycle. Diluent for the hydrolyzed gelatin also had a marked effect on recovery. The efficiency of release of Rhizobium spp. from an oxisol was in the following order for the diluents used: 0.1 M (NH(4))(2)HPO(4) > 0.1 M Na(2)HPO(4) = 0.1 M sodium-phosphate-buffered saline (pH 7.2) > 0.2 M NH(4)Cl > 0.2 KCl > NaCl = LiCl > water. PMID:16345824

  4. Diversity of repC plasmid-replication sequences in Rhizobium leguminosarum.

    Turner, S L; Rigottier-Gois, L; Power, R S; Amarger, N; Young, J P

    1996-07-01

    Homologues of the plasmid replicator gene repC were detected and characterized in a sample of Rhizobium leguminosarum strains. Conserved PCR primers were designed from published sequences of repC; they amplified a fragment of about 750 bp from 39 out of 41 strains tested, and also from several Sinorhizobium strains, including S. meliloti. Restriction endonuclease digestion showed that the PCR product from individual strains, though uniform in size, was often heterogeneous in sequence. PCR products from 24 field isolates of R. leguminosarum from France, Germany and the UK were cloned and partially sequenced from both ends. Phylogenies constructed from the 5' and 3' ends (200 bp each) were largely congruent and demonstrated four clearly defined groups plus several unique strains. Published Agrobacterium repC sequences fall within the phylogeny of R. leguminosarum sequences, though not within any of the four groups. Specific pairs of PCR primers were designed for each of the four groups; 29 out of 41 R. leguminosarum strains gave a PCR product of the expected size with more than one group-specific primer pair. We hypothesize that the sequence groups correspond to incompatibility groups of Rhizobium plasmids. PMID:8757735

  5. Variability of isolated colonies in bean nodulating Rhizobium strains before and after exposure to high temperature

    Raposeiras Rui

    2002-01-01

    Full Text Available Irregular response to bean plants to Rhizobium inoculation has been attributed to among other factors, low competitive ability, low N2 fixation efficiency and genetic instability of the symbiont. This genetic instability caused by high rates of genomic rearrangements and/or plasmid deletions can be accentuated by high temperatures. This fact may limit the utilization of these strains as inoculants, especially in tropical soils. In this study, the variability of isolated colonies derived from effective R. leguminosarum bv. phaseoli (SLP1.3 and BR 10.026 and R tropici (SLA2.2 and BR322 strains was evaluated before and after exposure to high temperatures (four consecutive thermal shocks at 45masculineC. This evaluation involved plant dry matter analysis of inoculated plants and genotypic (plasmid profile and genomic patterns via RAPD analysis of the Rhizobium strains. The results evidenced that high temperature improve the natural performance variability especially between isolated colonies from R. leguminosarum bv. phaseoli strains. The plasmid profile of isolated colonies from R. tropici strains were identical regardless of temperature treatment whereas isolated colonies from R. leguminosarum bv. phaseoli alterations were detected especially after the thermal treatment. The genomic patterns generated by AP-PCR showed more alterations and genetic variation in isolated colonies from R. leguminosarum bv. phaseoli strains indicating that R. tropici strains are more stable and lower affected by high temperature.

  6. Performance of fenugreek bioinoculated with Rhizobium meliloti strains under semi-arid condition.

    Singh, N K; Patel, D B

    2016-01-01

    Rhizobium meliloti strains were isolated from the fields of S.D. Agricultural University (Gujarat, India) and were maintained in the Congo Red Yeast Extract Mannitol Agar medium. These strains were tested for their effectiveness for fenugreek crop grown under semi-arid condition. Among the six Rhizobium strains, FRS-7 strain showed best plant growth parameters like shoot length, shoot dry weight, shoot total nitrogen, root length, root dry weight, root total nitrogen, seed yield, 1000 grain weight, number of root nodules, and nodules fresh and dry weight. The performance of this strain was better as compared to 20 kgN ha(-1) treatment through urea and was even far better over control plot. Seed yields obtained with FRS-7 during two years were 10.14 and 9.66 q ha(-1); which was about 36.8% and 45.9% high over control. This strain resulted in saving of about 20 kgN ha(-1) accompanied with better crop yield and soil health. Results of the present experiments can be utilized in integrated nutrient management for cultivation of fenugreek in semi-arid areas to provide sustainability to agricultural productivity in such regions. PMID:26930857

  7. Extended region of nodulation genes in Rhizobium meliloti 1021. I. Phenotypes of Tn5 insertion mutants

    Rhizobium meliloti Nod- mutant WL131, a derivative of wild-type strain 102F51, was complemented by a clone bank of wild-type R. meliloti 1021 DNA, and clone pRmJT5 was recovered. Transfer of pRmJT5 conferred alfalfa nodulation on other Rhizobium species, indicating a role in host range determination for pRmJT5. Mutagenesis of pRmJT5 revealed several segments in which transposon insertion causes delay in nodulation, and/or marked reduction of the number of nodules formed on host alfalfa plants. The set of mutants indicated five regions in which nod genes are located; one mutant, nod-216, is located in a region not previously reported to encode a nodulation gene. Other mutant phenotypes correlated with the positions of open reading frames for nodH, nodF and nodE, and with a 2.2-kb EcoRI fragment. A mutant in nodG had no altered phenotype in this strain. One nodulation mutant was shown to be a large deletion of the common nod gene region. The authors present a discussion comparing the various studies made on this extended nod gene region

  8. Effectiveness and competing capacity of native Rhizobium strains evaluated in IX Region soils

    Symbiotic nitrogen fixation in legumes reaches its optimum when the host plants are nodulated by highly competitive and effective Rhizobium strains. With the purpose of assessing competition and nitrogen fixing capacity of native Rhizobium leguminosarum bio-var trifolii strains, a greenhouse test was carried out using white clover (Trifolium re-pens) and four kinds of soils, which represent the main agroecological areas of the IX Region. Eleven strains were evaluated, they were both native and collected and were streptomycin sulphate antibiotic resistant. A nitrogen and a nitrogen-less without inoculation testers were used as controls. All pots received a solution of ammonium sulphate marked with 10% 15 N a.e, equivalent to 10 kg ha-1 of N. Rye-grass was used as reference crop, cv. Nu-i. In general, the evaluated strains were very efficient. After three or four cuts they became the only source of nitrogen for the plants. They were also very competitive, getting to over 70% of root infection with regard to those present in soils. In Curacautin and Tolten soils, biological nitrogen fixation begins later than other soils evaluated, which is coincident with soils having a higher nitrogen content. Symbiosis occurs when the soil nitrogen content exhausts or diminishes. (author)

  9. Studying Plant-Rhizobium Mutualism in the Biology Classroom: Connecting the Big Ideas in Biology through Inquiry

    Suwa, Tomomi; Williamson, Brad

    2014-01-01

    We present a guided-inquiry biology lesson, using the plant-rhizobium symbiosis as a model system. This system provides a rich environment for developing connections between the big ideas in biology as outlined in the College Board's new AP Biology Curriculum. Students gain experience with the practice of scientific investigation, from…

  10. Studying Plant-Rhizobium Mutualism in the Biology Classroom: Connecting the Big Ideas in Biology through Inquiry

    Suwa, Tomomi; Williamson, Brad

    2014-01-01

    We present a guided-inquiry biology lesson, using the plant-rhizobium symbiosis as a model system. This system provides a rich environment for developing connections between the big ideas in biology as outlined in the College Board's new AP Biology Curriculum. Students gain experience with the practice of scientific investigation, from…

  11. Enhanced Survival and Nodule Occupancy of Pigeon pea Nodulating Rhizobium sp. ST1 expressing fegA Gene of Bradyrhizobium japonicum 61A152

    G. Archana

    2009-01-01

    Full Text Available Problem statement: Rhizobial isolates belonging to genera (Rhizobium sp. and Mesorhizobium sp. in our laboratory produced only catecholate type of siderophores. Although FhuA and FegA (ferrichrome receptors homologs were found to be present in the sequenced genomes of few rhizobia (e.g., 1 in R. etli and 2 in Mesorhizobium sp. BNC1, laboratory isolates of the corresponding genera failed to utilize ferrichrome, a siderophore which is present in nanomolar concentrations in the soil. This inability was considered as a negative fitness factor with respect to rhizospheric colonization by these rhizobia. Approach: The 2.4 kb fegA gene (encoding ferrichrome receptor was amplified along with its native promoter from Bradyrhizobium japonicum 61A152 and cloned in a broad host range plasmid vector pUCPM18. The plasmid construct pFJ was transferred by conjugation into Rhizobium sp. ST1 to give transconjugant ST1pFJ12. The consequence of FegA expression on the transconjugant was tested under lab and soil conditions, using physiological experiments. Results: Ability of the transconjugant ST1pFJ12 to utilize ferrichrome and expression of a 79 kD protein band on the outer membrane of the transconjugant confirmed FegA expression. Transconjugant ST1pFJ12 exhibited increased growth rate as compared to the parent strain ST1, in minimal media containing ferrichrome as the sole iron source, confirming the positive effect of FegA expression. Inoculation of pigeon pea seedlings with transconjugant ST1pFJ12 led to a marked increase in plant growth parameters as compared to plants inoculated with the parent strain ST1, the effect being more pronounced when Ustilago maydis, a ferrichrome producer was co-inoculated in the systems. Nodule occupancy on pigeon pea plant when inoculated with the transconjugant ST1pFJ12 alone was 57% which increased to 66% when co-inoculated with U. maydis as compared with 37 and 30% respectively, seen with parental strain ST1 inoculation. Conclusion: The clear increase in nodule occupancy and higher rhizospheric colonization by the fegA transconjugants, presented in this study together with the previous research reported from our laboratory, led us to conclude that ferrichrome utilization ability played an important role in the rhizospheric colonization of the bioinoculant strains. Testing the ability to utilize hydroxamate siderophores therefore, holds prime importance in selecting an efficient biofertilizer strain.

  12. Final Environmental Statement related to the operation of Wolf Creek Generating Station, Unit No. 1. Docket No. STN 50-482, Kansas Gas and Electric Company, et al

    This final environmental statement contains the second assessment of the environmental impact associated with operation of Wolf Creek Generating Station Unit 1 pursuant to the National Environmental Policy Act of 1969 (NEPA) and 10 CFR Part 51, as amended, of the NRC's regulations. This statement examines: the affected environment, environmental consequences and mitigating actions, and environmental and economic benefits and costs. Land use and terrestrial- and aquatic-ecological impacts will be small. Air-quality impacts will also be small. However, steam fog from the station's cooling lake has the potential for reducing visibility over nearby roads and bridges. A fog-monitoring program for roads and bridges near the lake has been recommended. Impacts to historic and prehistoric sites will be negligible. Chemical discharges to the Neosho River are expected to have no appreciable impacts on water quality under normal conditions and will be required to meet conditions of the station's NPDES permit. The effects of routine operations, energy transmission, and periodic maintenance of rights-of-way and transmission line facilities should not jeopardize any populations of endangered or threatened species. No significant impacts are anticipated from normal operational releases of radioactivity. The risk associated with accidental radiation exposure is very low. The net socioeconomic effects of the project will be beneficial. The action called for is the issuance of an operating license for the Wolf Creek Generating Station Unit 1

  13. Genome Sequence of Rhizobium ecuadorense Strain CNPSo 671T, an Indigenous N2-Fixing Symbiont of the Ecuadorian Common Bean (Phaseolus vulgaris L.) Genetic Pool.

    Ribeiro, Renan Augusto; Delamuta, Jakeline Renata Marçon; Gomes, Douglas Fabiano; Souza, Renata Carolina; Chueire, Ligia Maria Oliveira; Hungria, Mariangela

    2015-01-01

    Rhizobium ecuadorense CNPSo 671(T) was isolated from a common bean nodule in Ecuador. The draft genome brings novelty about indigenous rhizobial species in centers of genetic diversity of the legume. PMID:26383667

  14. Mission related to regulation and development of the photovoltaic sector in France. Final report; Mission relative a la regulation et au developpement de la filiere photovoltaique en France. Rapport final

    Charpin, J.M; Sine, A.; Helleisen, Ph.; Tlili, C. [Inspection Generale des Finances - IGF, 75 - Paris (France); Trink, C.; Stoffaes, Ch. [Conseil General de l' Industrie de l' Energie et des Technologies - CGIET, 75 - Paris (France)

    2010-07-01

    This report first gives an overview of the development of the photovoltaic stock in France (high potential with a middle term development constrained by high costs, consequences of a very strong increase of demands at the end of 2009, perspective of development at a rather high rate). Then, it outlines and discusses the financial consequences of such a high rate development, and the inadequacy between industrial objectives and development rate. It presents a development plan for this sector, stresses the need to implement new purchase obligation measures before the summer 2010, and to define a global action plan to be implemented at the beginning of 2011 for the development of photovoltaic electricity. Elements of international comparison are finally proposed

  15. Effectiveness of halo-tolerant, auxin producing Pseudomonas and Rhizobium strains to improve osmotic stress tolerance in mung bean (Vigna radiata L.)

    Maqshoof Ahmad; Zahir, Zahir A.; Farheen Nazli; Fareeha Akram; Muhammad Arshad; Muhammad Khalid

    2013-01-01

    Halo-tolerant, auxin producing bacteria could be used to induce salt tolerance in plants. A number of Rhizobium and auxin producing rhizobacterial strains were assessed for their ability to tolerate salt stress by conducting osmoadaptation assay. The selected strains were further screened for their ability to induce osmotic stress tolerance in mung bean seedlings under salt-stressed axenic conditions in growth pouch/jar trials. Three most effective strains of Rhizobium and Pseudomonas contain...

  16. Effectiveness of halo-tolerant, auxin producing Pseudomonas and Rhizobium strains to improve osmotic stress tolerance in mung bean (Vigna radiata L.

    Maqshoof Ahmad

    2013-12-01

    Full Text Available Halo-tolerant, auxin producing bacteria could be used to induce salt tolerance in plants. A number of Rhizobium and auxin producing rhizobacterial strains were assessed for their ability to tolerate salt stress by conducting osmoadaptation assay. The selected strains were further screened for their ability to induce osmotic stress tolerance in mung bean seedlings under salt-stressed axenic conditions in growth pouch/jar trials. Three most effective strains of Rhizobium and Pseudomonas containing ACC-deaminase were evaluated in combination, for their ability to induce osmotic stress tolerance in mung bean at original, 4, and 6 dS m-1 under axenic conditions. Results showed that sole inoculation of Rhizobium and Pseudomonas strains improved the total dry matter up to 1.4, and 1.9 fold, respectively, while the increase in salt tolerance index was improved up to 1.3 and 2.0 fold by the Rhizobium and Pseudomonas strains, respectively. However, up to 2.2 fold increase in total dry matter and salt tolerance index was observed due to combined inoculation of Rhizobium and Pseudomonas strains. So, combined application of Rhizobium and Pseudomonas strains could be explored as an effective strategy to induce osmotic stress tolerance in mung bean.

  17. Agrobacterium strains isolated from root nodules of common bean specifically reduce nodulation by Rhizobium gallicum.

    Mrabet, Moncef; Mnasri, Bacem; Romdhane, Samir Ben; Laguerre, Gisèle; Aouani, Mohamed Elarbi; Mhamdi, Ridha

    2006-05-01

    In a previous work, we showed that non-nodulating agrobacteria strains were able to colonize root nodules of common bean. Both rhizobia and agrobacteria co-existed in the infected nodules. No impact on symbiosis was found in laboratory conditions when using sterile gravel as a support for growth. In this study, soil samples originating from different geographic and agronomic regions in Tunisia were inoculated with a mixture of agrobacteria strains isolated previously from root nodules of common bean. A significant effect on nodulation and vegetal growth of common bean was observed. Characterization of nodulating rhizobia and comparison with non-inoculated controls showed a biased genetic structure. It seemed that Rhizobium gallicum was highly inhibited, whereas nodulation by Sinorhizobium medicae was favored. Co-inoculation of non-sterile soils with R. gallicum and agrobacteria confirmed these findings. In vitro antibiosis assays indicated that agrobacteria exercised a significant antagonism against R. gallicum. PMID:16629759

  18. Isolation of a strain of Agrobacterium tumefaciens (Rhizobium radiobacter) utilizing methylene urea (ureaformaldehyde) as nitrogen source.

    Koivunen, Marja E; Morisseau, Christophe; Horwath, William R; Hammock, Bruce D

    2004-03-01

    Methylene ureas (MU) are slow-release nitrogen fertilizers degraded in soil by microbial enzymatic activity. Improved utilization of MU in agricultural production requires more knowledge about the organisms and enzymes responsible for its degradation. A Gram-negative, MU-degrading organism was isolated from a soil in Sacramento Valley, California. The bacterium was identified as Agrobacterium tumefaciens (recently also known as Rhizobium radiobacter) using both genotypic and phenotypic characterization. The pathogenic nature of the organism was confirmed by a bioassay on carrot disks. The MU-hydrolyzing enzyme (MUase) was intracellular and was induced by using MU as a sole source of nitrogen. The bacterial growth was optimized in NH4Cl, urea, or peptone, whereas the production and specific activity of MUase were maximized with either NH4Cl or urea as a nitrogen source. The result has a practical significance, demonstrating a potential to select for this plant pathogen in soils fertilized with MU. PMID:15105883

  19. Isolation and Identification of Rhizobium Bacteriophages in Guilan and Isfahan Provinces, Iran

    2008-01-01

    Full Text Available Rhizobia are one of the most important nitrogen fixing bacteria which interact specifically with legume species and induce formation of root nodules. Selective elimination of rhizobia is induced by rhizobiophages in soil. Bacteriophages can also be used for phage typing in epidemiological studies. Rhizobia were isolated from root nodules of Cicer arietinum L., Phaseolus vulgaris L. and Trigonella foenum-graecum L. plants grown in Jir-Gavabar of Roudsar and 3 areas of Isfahan. Four rhizobiophages were isolated from the same soils and purified. Morphology of the phages were studied by electron microscopy. Based on morphological features, the phages appear to be members of Myoviridae, Siphoviridae and Microviridae families. It was found for the first time that phages rather than siphoviridae are also able to infect Rhizobium leguminosarum bv. viciae ( Cicer arietinum L..

  20. Effect of Rhizobium inoculation of seeds and foliar fertilization on productivity of Pisum sativum L.

    Tadeusz Zając

    2013-07-01

    Full Text Available Pea (Pisum sativum L. is the second most important grain legume crop in the world which has a wide array of uses for human food and fodder. One of the major factors that determines the use of field pea is the yield potential of cultivars. Presently, pre-sowing inoculation of pea seeds and foliar application of microelement fertilizers are prospective solutions and may be reasonable agrotechnical options. This research was undertaken because of the potentially high productivity of the 'afila' morphotype in good wheat complex soils. The aim of the study was to determine the effect of vaccination with Rhizobium and foliar micronutrient fertilization on yield of the afila pea variety. The research was based on a two-year (2009–2010 controlled field experiment, conducted in four replicates and carried out on the experimental field of the Bayer company located in Modzurów, Silesian region. experimental field soil was Umbrisol – slightly degraded chernozem, formed from loess. Nitragina inoculant, as a source of symbiotic bacteria, was applied before sowing seeds. Green area index (GAI of the canopy, photosynthetically active radiation (PAR, and normalized difference vegetation index (NDVI were determined at characteristic growth stages. The presented results of this study on symbiotic nitrogen fixation by leguminous plants show that the combined application of Nitragina and Photrel was the best combination for productivity. Remote measurements of the pea canopy indexes indicated the formation of the optimum leaf area which effectively used photosynthetically active radiation. The use of Nitragina as a donor of effective Rhizobium for pea plants resulted in slightly higher GAI values and the optimization of PAR and NDVI. It is not recommended to use foliar fertilizers or Nitragina separately due to the slowing of pea productivity.

  1. Typing of rhizobia by PCR DNA fingerprinting and PCR-restriction fragment length polymorphism analysis of chromosomal and symbiotic gene regions: application to Rhizobium leguminosarum and its different biovars.

    Laguerre, G; Mavingui, P; Allard, M R; Charnay, M P; Louvrier, P; Mazurier, S I; Rigottier-Gois, L; Amarger, N

    1996-06-01

    Characterization of 43 strains of Rhizobium leguminosarum biovars viciae, trifolii, and phaseoli was performed by two methodologies based on PCR amplification, i.e., PCR DNA fingerprinting of interrepeat sequences and restriction fragment length polymorphism (RFLP) analysis of PCR -amplified chromosomal and symbiotic gene regions. Groupings generated by PCR DNA fingerprinting with either extragenic palindromic repetitive primers or two different single random primers were correlated with similar levels of resolution. Although less discriminating, PCR-RFLP analysis of intergenic spacer between genes coding for 16S and 23S rRNA (16S and 23S rDNA) yielded intraspecific polymorphisms. The classification of strains was independent of the biovar status and was in agreement with those obtained by PCR DNA fingerprinting. Intrabiovar variation within symbiotic gene regions was detected by PCR-RFLP analysis of nifDK and nodD gene regions, but the strains were grouped according to the biovar. The rDNA intergenic spacer and nif primers were verified to be universal for rhizobial species by testing of various reference strains, whereas the nod primers designed in this study were biovar or species specific for R. leguminosarum and Rhizobium etli. Classifications of R. leguminosarum strains by the PCR-based methods were correlated with those previously obtained by conventional total DNA restriction profile comparisons and RFLP analysis using chromosomal and symbiotic gene probes. Ranges of discriminating powers were also equivalent between the two approaches. However, the PCR-based methods are much less time-consuming and are therefore more convenient. PMID:8787401

  2. Random amplified polymorphic DNA analysis of effective Rhizobium sp. associated with beans cultivated in brazilian cerrado soils Caracterização, via RAPD, de estirpes efetivas de Rhizobium sp associadas ao feijoeiro cultivado em solos de cerrado no Brasil

    Isnia Aparecida de Oliveira

    2000-03-01

    Full Text Available Efficient bean nodulating Rhizobium strains, isolated from different Brazilian cerrado soils, were characterized by RAPD. This study showed great genetic heterogeneity among R. tropici and R. leguminosarum bv. phaseoli strains and allowed the constitution of genetic clusters, besides indicating the most suitable primers for this characterization. The groups of genetically distinct strains can be used in competitiveness studies to select appropriate Rhizobium strains for bean inoculation in cerrado soils.Estirpes de Rhizobium eficientes na nodulação do feijoeiro, isoladas de diferentes solos da região do cultivo dessa leguminosa nos cerrados brasileiros, foram caracterizadas via RAPD. Esse estudo mostrou grande heterogeneidade genética entre as estirpes de R. tropici e R. leguminosarum bv. phaseoli testadas e permitiu a definição de grupos genéticos, além de indicar os "primers" mais adequados para essa caracterização. Os grupos de estirpes geneticamente distintas podem ser usados em estudos de competitividade, importantes para obtenção de resultados positivos na inoculação dessa leguminosa em solos de cerrado.

  3. Study of final states involving 2 particle jets and missing energy with the DELPHI detector at LEP; Etude des etats finals contenant deux jets de particules et de l'energie manquante avec le detecteur DELPHI a LEP

    Ferrer Ribas, E

    2000-05-09

    The observation of the Higgs boson would be of great importance for the understanding of the electroweak symmetry breaking. In the framework of the Minimal Supersymmetric extension of the Standard Model (MSSM), the lightest Higgs boson is neutral and scalar, and its mass must be less than 130 GeV/c{sup 2}. In this thesis, we have studied events characterized by the presence of two particle jets and missing energy. This is a very clear signature of the production of the Higgs boson in association with a Z{sup 0} boson. This production is followed by the decay of the Higgs boson into a bb-bar pair and the Z{sup 0} boson in {nu}{nu}-bar pair. In these studies, it is important to detect all particles in order to achieve a good resolution in energy. For these reasons, we have devoted ourselves to improving DELPHI's hermeticity mainly in the regions located at 40 deg C and 140 deg C. Using the data collected by the DELPHI detector at LEP in 1998 and in 1999 at four different energies in the centre of mass ({radical}s = 189, 196, 200 and 202 GeV), no signal has been observed, allowing us to exclude the Higgs boson at 95 % confidence level up to a mass of: m{sub H} > 98.0 (98.5) GeV/c{sup 2} at 95% C.L. this analysis; m{sub H} > 103.9 (106.3) GeV/c{sup 2} at 95% C.L. DELPHI combined. The values in parentheses show the expected limits and indicate the sensitivity of the analysis. If these results are interpreted in the framework of the MSSM we obtain: m{sub h} > 85.0 (85.3) GeV/c{sup 2} at 95% C.L. Studying the same topology, we have also searched for a Higgs boson decaying into a pair of non detectable particles (Invisible Higgs) in association with a Z{sup 0} boson decaying into a quark/antiquark pair. In this case too, no signal has been observed, which can be translated into a lower limit on the mass of the Higgs boson at 95% confidence level: m{sub h{sub inv}} > 105.5 (105.3) GeV/c{sup 2} at 95% C.L. Finally, we have measured the production cross section of a pair of Z{sup 0} bosons where one decays to a quark/antiquark pair (all flavours) and the other to a pair of neutrinos. The result is in very good agreement with the value predicted by the Standard Model: {sigma}{sup NC02}/{sigma}{sup MS} = 0.94{+-}0.25 this analysis; {sigma}{sup NC02}/{sigma}{sup MS} = 1.04{+-}0.12 DELPHI combined. (author)

  4. Tolerance Of Several Rhizobium Strain/Isolate To A1 and Their Interaction With Several Soybean Mutants

    Research activities to study the interaction of several soybean mutant and rhizobium strain/isalates were carried out. The first experiment to be involved screening of nine strain/isolates for tolerance to A1 acid stress. Five strains/isolates were considered tolerance. Further experiment with three strains/isolates with difference A1 concentrations, showed that the isolate no. 06 had the highest growth rate followed by isolate 09 and TAL 102. Experiment on interaction of five soybean mutant/varieties with those strains/isolates were carried out in nutrient culture. Mutant no. 21 and 43 showed better growth in solution containing 50 uM A1. Good nodulation occured in mutant no. 23 inoculated with Rhizobium isolate no. 06. This good symbiotic association should be studied further at higher A1 concentration. (authors). 14 refs, 6 tabs

  5. Dual inoculation with an Aarbuscular Mycorrhizal fungus and Rhizobium to facilitate the growth of alfalfa on coal mine substrates

    Wu, F.Y.; Bi, Y.L.; Wong, M.H. [China University of Mining & Technology, Beijing (China)

    2009-07-01

    A pot experiment was conducted to investigate the effects of Glomus mosseae and Rhizobium on Medicago sativa grown on three types of coal mine substrates, namely a mixture of coal wastes and sands (CS), coal wastes and fly ash (CF), and fly ash (FA). Inoculation with Rhizobium alone did not result in any growth response but G. mosseae alone displayed a significant effect on plant growth. G. mosseae markedly increased the survival rate of M. sativa in CS substrate. In CF and FA substrates the respective oven dry weights of M. sativa inoculated with G. mosseae were 1.8 and 5.1 times higher than those without inoculation. Based on nitrogen (N), phosphorus (P) and potassium (K) uptake and legume growth, the results also show that dual inoculation in CS and CF substrates elicited a synergistic effect. This indicates that inoculation with arbuscular mycorrhizal (AM) fungi may be a promising approach for revegetation of coal mine substrates.

  6. Biodegradation of Selected Nigerian Fruit Peels by the use of a Non-pathogenic Rhizobium species CWP G34B

    Esther Boboye, Bolatito; Ajayi, George Olarewaju

    2012-01-01

    This study was carried out to determine the ability of Rhizobium species CWP G34B to degrade the peels of selected Nigerian fruits. The potential of the bacterium to digest some carbon sources (lactose, maltose, sucrose and mannitol) and peels of some Nigerian fruits (pineapple, orange, plantain, banana, pawpaw and mango fruits) was investigated by growing the organism on the substances separately after which DNSA reagent method was used to quantify glucose released into the mediu...

  7. Quantitative 1 H NMR spectroscopy analysis of the poly(3-hydroxy alkanoate) extracted from Rhizobium meliloti cells

    1H NMR analysis was carried out to determine the nature and the concentration of the poly(3-hydroxyalkanoate) (PHA) accumulated by Rhizobium meliloti M5N1. The PHA was identified as being poly(3-hydroxybutyrate) (PHB). Benzene was shown to meet all the requirements of an internal reference for PHB quantification. NMR data were in good agreement with corresponding data obtained by Gas Chromatography (GC) analysis. (authors). 4 refs., 2 figs

  8. Population Dynamics of Rhizobium leguminosarum Tn5 Mutants with Altered Cell Surface Properties Introduced into Sterile and Nonsterile Soils

    Postma, J.; Hok-A-Hin, C.H.; Schotman, J. M. T.; Wijffelman, C A; van Veen, J.A.

    1991-01-01

    The influence of cell surface properties on attachment to soil particles and on population dynamics of introduced bacteria was studied in sterilized and nonsterilized loamy sand and silt loam. Rhizobium leguminosarum RBL5523 and three Tn5 mutants (RBL5762, RBL5810, and RBL5811) with altered cell surface properties were used. Cellulose fibrils were not produced by RBL5762. Both RBL5810 and RBL5811 produced 80 to 90% less soluble exopolysaccharides and RBL5811 had, in addition, an altered lipop...

  9. High-quality permanent draft genome sequence of Rhizobium sullae strain WSM1592; a Hedysarum coronarium microsymbiont from Sassari, Italy

    Yates, Ron; Howieson, John; De Meyer, Sofie E.; Tian, Rui; Seshadri, Rekha; Pati, Amrita; Woyke, Tanja; Markowitz, Victor; Ivanova, Natalia; Kyrpides, Nikos; Loi, Angelo; Nutt, Brad; Garau, Giovanni; Sulas, Leonardo; Reeve, Wayne

    2015-01-01

    Rhizobium sullae strain WSM1592 is an aerobic, Gram-negative, non-spore-forming rod that was isolated from an effective nitrogen (N2) fixing root nodule formed on the short-lived perennial legume Hedysarum coronarium (also known as Sulla coronaria or Sulla). WSM1592 was isolated from a nodule recovered from H. coronarium roots located in Ottava, bordering Sassari, Sardinia in 1995. WSM1592 is highly effective at fixing nitrogen with H. coronarium, and is currently the commercial Sulla inocula...

  10. Catabolite repression and role of cyclic AMP in CO2 fixation and H2 metabolism in Rhizobium spp.

    McGetrick, A M; Goulding, C F; Manian, S S; O'Gara, F.

    1985-01-01

    CO2 fixation in Rhizobium meliloti was repressed by a variety of organic carbon sources. Cellular cyclic AMP levels were similar in repressed and nonrepressed cultures. Exogenous cyclic AMP or additional copies of the adenyl cyclase gene in cells experiencing repression failed to affect the rates of CO2 fixation. However, in R. japonicum catabolite repression of H2 utilization was partially circumvented by the presence of the R. meliloti adenyl cyclase gene.

  11. Mutualism and Adaptive Divergence: Co-Invasion of a Heterogeneous Grassland by an Exotic Legume-Rhizobium Symbiosis

    Porter, Stephanie S; Stanton, Maureen L.; Rice, Kevin J.

    2011-01-01

    Species interactions play a critical role in biological invasions. For example, exotic plant and microbe mutualists can facilitate each other's spread as they co-invade novel ranges. Environmental context may influence the effect of mutualisms on invasions in heterogeneous environments, however these effects are poorly understood. We examined the mutualism between the legume, Medicago polymorpha, and the rhizobium, Ensifer medicae, which have both invaded California grasslands. Many of these ...

  12. Host-Symbiont Specificity Expressed during Early Adsorption of Rhizobium meliloti to the Root Surface of Alfalfa †

    Anollés, Gustavo Caetano; Favelukes, Gabriel

    1986-01-01

    Early (4 h) adsorption of Rhizobium meliloti L5-30 in low numbers to alfalfa roots in mineral solution was examined for competition with other bacterial strains. All tested competitor strains decreased the adsorption of L5-30 by extents which depended on the strain and its concentration. The decrease of adsorption by R. meliloti competitors (all of them infective in alfalfa) was nearly complete at saturation (97 to 99% decrease). All other heterologous rhizobia and Agrobacterium tumefaciens a...

  13. PssP2 Is a Polysaccharide Co-Polymerase Involved in Exopolysaccharide Chain-Length Determination in Rhizobium leguminosarum

    Marczak, Ma?gorzata; Matysiak, Paulina; Kutkowska, Jolanta; Skorupska, Anna

    2014-01-01

    Production of extracellular polysaccharides is a complex process engaging proteins localized in different subcellular compartments, yet communicating with each other or even directly interacting in multicomponent complexes. Proteins involved in polymerization and transport of exopolysaccharide (EPS) in Rhizobium leguminosarum are encoded within the chromosomal Pss-I cluster. However, genes implicated in polysaccharide synthesis are common in rhizobia, with several homologues of pss genes iden...

  14. Rhizobium leguminosarum como organismo biocontrolador de la interacción hospedero-patógeno: clavel (dianthus caryophyllus) – fusarium oxysporum f. sp. dianthi

    Cheol Woo Lee Park; Yolanda Navarro de Navarro

    2010-01-01

    Se investigó el efecto de biocontrol de Rhizobium leguminosarum (R. leguminosarum) cepa B, contra Fusarium oxysporum f.sp.dianthi (FOD) raza 2, en la interacción Clavel - FOD. Se utilizó la raza 2 de FOD por ser la de mayor patogenicidad y distribución en las fincas de cultivo de clavel en Colombia. Para ello se establecieron las condiciones de inoculación de FOD sobre cultivos establecidos de R . leguminosarum, variando la concentración in vitro de la bacteria. Se encontró una reducción en e...

  15. Symbiotic Efficiency of Native and Exotic Rhizobium Strains Nodulating Lentil (Lens culinaris Medik.) in Soils of Southern Ethiopia

    Wondwosen Tena; Endalkachew Wolde-Meskel; Fran Walley

    2016-01-01

    Lentil plays a major role in the food and nutritional security of low income Ethiopian families because of the high protein content of their seed; however, their productivity typically is low largely due to soil fertility limitations. Field and pot experiments were conducted during the 2011 cropping season to determine the effectiveness of Rhizobium strains on two cultivars of lentil in Southern Ethiopia. Six rhizobial inoculant treatments (four indigenous and two commercial inoculants), a ni...

  16. Growth and yield of groundnut (Arachis hypogaea L.) as influenced by weed management practices and Rhizobium inoculation.

    Jhala, A; Rathod, P H; Patel, K C; Van Damme, P

    2005-01-01

    Groundnut (Arachis hypogaea L.) productivity in India is low, because of many problems beset in its cultivation. One of the serious problems are weeds. Groundnut yield losses due to weeds have been estimated as high as 24 to 70 percent. This has created a scope for using herbicides in groundnut crop. A field investigation was carried out during kharif (rainy) season of 2001-2002 on a sandy loam soil at College Agronomy Farm, B.A. College of Agriculture, Gujarat Agricultural University, Anand, India to study the effect of weed management practices and Rhizobium inoculation on growth and yield of groundnut (Arachis hypogaea L.). Ten weed control treatments, comprising four treatments of sole application of fluchloralin, pendimethalin, butachlor and metolachlor, respectively each applied at 1.0 kg ha(-1); four treatments comprising of an application of the same herbicides at the same levels coupled with one hand weeding at 30 DAS; one weed-free treatment (hand weedings at 15, 30, 45 DAS); and one unweeded control. All 10 treatmets were combined with and without Rhizobium inoculation (i.e. a total of 20 treatment combinations) under a factorial randomized complete block design (FRBD) with four replications. Minimum weed dry matter accumulation (70 kg/ha) with higher weed control efficiency (90.70%) was recorded under an integrated method i.e. pendimethalin at 1.0 kg ha(-1) + hand weeding at 30 DAS, which also resulted in maximum pod yield (1773.50 kg ha(-1)). This treatment was comparable to fluchloralin applied at 1.0 kg ha(-1) combined with hand- weeding at 30 DAS. Weedy conditions in the unweeded control treatment reduced pod yield by 29.90-35.95% as compared to integrated method. Significantly higher pod yield was obtained with Rhizobium inoculation than the mean value of all treatments without inoculation. For most agronomical parameters examined, Rhizobium inoculation and weed control treatments were independent in their effect. PMID:16637221

  17. VARIATION IN RHIZOBIUM GROWTH DUE TO SEED AND ROOT EXUDATES RELEASED FROM GAMMA IRRADIATED GLYCINE MAX SEEDS

    In this study, seeds of Glycine max Giza 122 were irradiated with gamma rays from 60Co source at various doses (10 to 200 Gy), sterilized and soaked into an aerated solution of CaSO4 (1 mmol and pH 6.5). The capacities of the released seed exudates (SEs) and root exudates (REs) to promote Rhizobium leguminosarum growth were investigated as well as biochemical analysis of the exudates was carried out. SE of both control and gamma irradiated seeds resulted in a higher Rhizobium population and polysaccharide production than RE. Relative to control, the highly effective doses in Rhizobium growth and polysaccharide production were 25 and 200 Gy; the former was a promoter while the later was an inhibitor. HPLC analysis of soluble carbohydrates revealed the presence of glucose (Glu), rhamnose (Rha) and fructose (Fru) in the SE and RE. Protein content in SE was lower than that in RE; the highest values were due to 10 Gy and 25 Gy in SE and RE, respectively. Free amino acids content in SE was increased up to 25 Gy then decreased while RE was increased by increasing gamma doses from 10 to 200 Gy

  18. Sulphation of Rhizobium sp. NGR234 Nod factors is dependent on noeE, a new host-specificity gene.

    Hanin, M; Jabbouri, S; Quesada-Vincens, D; Freiberg, C; Perret, X; Promé, J C; Broughton, W J; Fellay, R

    1997-06-01

    Rhizobia secrete specific lipo-chitooligosaccharide signals (LCOs) called Nod factors that are required for infection and nodulation of legumes. In Rhizobium sp. NGR234, the reducing N-acetyl-D-glucosamine of LCOs is substituted at C6 with 2-O-methyl-L-fucose which can be acetylated or sulphated. We identified a flavonoid-inducible locus on the symbiotic plasmid pNGR234a that contains a new nodulation gene, noeE, which is required for the sulphation of NGR234 Nod factors (NodNGR). noeE was identified by conjugation into the closely related Rhizobium fredii strain USDA257, which produces fucosylated but non-sulphated Nod factors (NodUSDA). R. fredii transconjugants producing sulphated LCOs acquire the capacity to nodulate Calopogonium caeruleum. Furthermore, mutation of noeE (NGRdelta noeE) abolishes the production of sulphated LCOs and prevents nodulation of Pachyrhizus tuberosus. The sulphotransferase activity linked to NoeE is specific for fucose. In contrast, the sulphotransferase NodH of Rhizobium meliloti seems to be less specific than NoeE, because its introduction into NGRdelta noeE leads to the production of a mixture of LCOs that are sulphated on C6 of the reducing terminus and sulphated on the 2-O-methylfucose residue. Together, these findings show that noeE is a host-specificity gene which probably encodes a fucose-specific sulphotransferase. PMID:9218762

  19. Synthesis of new glycosaminoglycans-like families by regioselective oxidation followed by sulphation of glucoglucuronan from Rhizobium sp. T1.

    Redouan, Elboutachfaiti; Emmanuel, Petit; Philippe, Michaud; Bernard, Courtois; Josiane, Courtois; Cedric, Delattre

    2012-08-01

    Glycosaminoglycan-like polysaccharides were prepared from Rhizobium sp. T1 polysaccharide using the TEMPO (nitroxyl radical 2,2,6,6-tetramethylpiperidine-1-oxyl radical) mediated oxidation. The structure of this new polyglucuronic acid sodium salt was analyzed by (13)C NMR spectra and HPAEC-PAD chromatography. Therefore, new polysaccharide containing only glucuronic acid monomers in both β-(1,3) and β-(1,4) linkage was obtained by the complete TEMPO-mediated oxidation of C6 primary hydroxyl groups of glucose of glucoglucuronan from Rhizobium sp. T1. Sulphation of this β-(1,3),β-(1,4)-polyglucuronic acid sodium salt was carried out using SO3/DMF reagent. These results suggested a new synthetic route using both TEMPO-mediated oxidation and sulphation of polysaccharides from Rhizobium sp. in developing glycosaminoglycans mimic to enhance the profitability of its low-cost production and processing industries. This novel carbohydrate derivative might find use as cheaper surrogates of glycosaminoglycans in the cosmetics and pharmaceutical fields. PMID:24750940

  20. Perturabation of nodular operation under salt and water deficit stress in rhizobium common bean symbiosis

    This work aims at the search for markers of tolerance to the osmotic stress and nodular efficiency of symbiosis Haricot Rhizobium. Thus, after having fixed the best period of hydroponic culture, we showed that a severe salt treatment generated an inhibition of the parameters of growth and nodulation. These inhibitions are accompanied by an inhibition of the enzymatic activities: ascorbate peroxidase (APX) and catalase (CAT), but an activation of peroxidase (POX) and superoxide dismutase (SOD), suggesting that these two antioxydants can be biochemical markers of the tolerance to salinity. To check the validity of these markers and to see the participation of the vegetable genotype in the response to the stress, we compared the effect of two concentrations salt 25 and 50 mM NaCe at two contrasting genotypes BAT477 tolerant and sensitive COCOT. This study illustrates the role of the vegetable genotype in the tolerance and efficiency and emphasize a significant result that SOD and POX constitute biochemical markers of tolerance to salinity. In order to ensure itself of the validity of this assumption in the event of water deficit stress, a treatment of 50 mM mannitol is applied to 16 symbioses formed by four genotypes of bean BAT477, COCOT, Flamingo and BRB17 inoculated by four strains of rhizobium CIAT899, 12 to 3, 1 to 6 and 8 to 3. This study permits us to make a screening of these symbioses according to their efficiency and their tolerance based on parameters of growth, of fixing and extent of the antioxydant enzymatic activities. It gets clear that the response of enzymatic antioxydants is in relation to the intrinsic potentialities of the partners of symbioses and appears to act as of the first stages of recognition plants bacterium. It will be retained that activities POX and SOD are markers of nodular tolerance. The CAT is the enzyme most connected to each partner of symbiosis and the APX would play a rather functional role. The heterogeneity of found answer indicates the great importance of the interaction of the two partners of symbiosis and of their contribution in great variability. The whole of results permits us to choose contrasting symbioses for better elucidating the mechanisms of nodular operation in response to the osmotic stress. (author). 282 refs

  1. Selection of Rhizobium strain from Wonogiri, Central Java on the growth of soybean (Glycine max L. on the sand sterile medium in greenhouse

    SRI PURWANINGSIH

    2005-07-01

    Full Text Available An experiment on the selection of Rhizobium strain from Wonogiri, Central Java on the growth of soybean (Glycine max L. on the sand sterile medium in green house. The aim of the experiment the selection and potency of the Rhizobium strain to increase the growth of soybean. The experiment was carried out in green house condition in Microbiology Division, Research Center for Biology-LIPI with sterile sand medium. The research design was Completely Randomized Design with three replications for each treatment. The Rhizobium strains used were 1 W (isolated from bean, Vigna radiata, 2 W (isolated from soybean, 3 W (isolated from bean, 4 W (isolated from soybean, 5 W (isolated from soybean, 6 W (isolated from peanut, Arachis hypogaea, 7 W (isolated from peanut, 8 W (isolated from peanut, the controls were uninoculated with Rhizobium strain and without urea fertilizer (K1, uninoculated and with urea fertilizer equal 100 kg/ha (K2. The plants were harvested after 50 days, the variable of investigation were the dry weight of canopy, roots, nodules root, total plants, number of nodules and ‘symbiotic capacity”. The results showed that all of experiment plant which be inoculated with Rhizobium able to form nodule. Strain of 2 W (isolated from soybean has given the best effects on the growth of soybean.

  2. Genomic and phenotypic characterization of Rhizobium gallicum phage vB_RglS_P106B.

    Halmillawewa, Anupama P; Restrepo-Córdoba, Marcela; Yost, Christopher K; Hynes, Michael F

    2015-03-01

    The phage P106B (vB_RglS_P106B) is a Siphoviridae phage with a narrow spectrum of infectivity, which has been isolated from soils with a history of pea cultivation. The trapping host of P106B is an indigenous strain of Rhizobium gallicum (SO14B-4) isolated from soils associated with Vicia cracca. Phenotypic characterization of the phage revealed that P106B has an approximate burst size of 21 p.f.u. per infected cell with 60 min and 100 min eclipse and latent periods, respectively. Phage P106B was unable to transduce under the conditions tested. The genome of P106B is 56?024 bp in length with a mean DNA G+C content of 47.9?%. The complete genome sequence contains 95 putative ORFs and a single tRNA gene coding for leucine with the anticodon TTA. Putative functions could only be assigned to 22 of the predicted ORFs while a significant number of ORFs (47) shared no sequence similarities to previously characterized proteins. The remaining 26 putative protein-coding genes exhibited a sequence resemblance to other hypothetical proteins. No lysogeny-related genes were found in the P106B genome. PMID:25627439

  3. Evaluation of the Galega-Rhizobium galegae system for the bioremediation of oil-contaminated soil

    Suominen, L.; Jussila, M.M.; Makelainen, K.; Lindstrom, K. [University of Helsinki (Finland). Dept. of Applied Chemistry and Microbiology; Romantschuk, M. [University of Helsinki (Finland). Dept. of Biosciences

    2000-07-01

    The bioremediation potential of a nitrogen-fixing leguminous plant, Galega orientalis, and its microsymbiont Rhizobium galegae was evaluated in BTX (benzene, toluene, xylene)-contaminated soils in microcosm and mesocosm scale. To measure the intrinsic tolerance of the organisms to m-toluate, a model compound representing BTX, G. orientalis and R. galegae were cultivated under increasing concentrations of m-toluate alone and in association with Pseudomonas putida pWWO, a bacterial strain able to degrade toluene-derived compounds. The test plants and rhizobia remained viable in m-toluate concentrations as high as 3000 ppm. Plant growth was inhibited in concentrations higher than 500 ppm, but restituted when plants were transferred into m-toluate-free medium. Nodulation was blocked under the influence of m-toluate, but was restored after the plants were transferred into the non-contaminated media. In the mesocosm assay the Galega plants showed good growth, modulation and nitrogen fixation, and developed a strong rhizosphere in soils contaminated with oil or spiked with 2000 ppm m-toluate. Thus, this legume system has good potential for use on oil-contaminated sites. (author)

  4. Escherichia coli BdcA controls biofilm dispersal in Pseudomonas aeruginosa and Rhizobium meliloti

    Wood Thomas K

    2011-10-01

    Full Text Available Abstract Background Previously we showed that BdcA controls Escherichia coli biofilm dispersal by binding the ubiquitous bacterial signal cyclic diguanylate (c-di-GMP; upon reducing the concentration of c-di-GMP, the cell shifts to the planktonic state by increasing motility, decreasing aggregation, and decreasing production of biofilm adhesins. Findings Here we report that BdcA also increases biofilm dispersal in other Gram-negative bacteria including Pseudomonas aeruginosa, Pseudomonas fluorescens, and Rhizobium meliloti. BdcA binds c-di-GMP in these strains and thereby reduces the effective c-di-GMP concentrations as demonstrated by increases in swimming motility and swarming motility as well as by a reduction in extracellular polysaccharide production. We also develop a method to displace existing biofilms by adding BdcA via conjugation from E. coli in mixed-species biofilms. Conclusion Since BdcA shows the ability to control biofilm dispersal in diverse bacteria, BdcA has the potential to be used as a tool to disperse biofilms for engineering and medical applications.

  5. Bacterial Growth Rates and Competition Affect Nodulation and Root Colonization by Rhizobium meliloti.

    Li, D M; Alexander, M

    1986-10-01

    The addition of streptomycin to nonsterile soil suppressed the numbers of bacterial cells in the rhizosphere of alfalfa (Medicago sativa L.) for several days, resulted in the enhanced growth of a streptomycin-resistant strain of Rhizobium meliloti, and increased the numbers of nodules on the alfalfa roots. A bacterial mixture inoculated into sterile soil inhibited the colonization of alfalfa roots by R. meliloti, caused a diminution in the number of nodules, and reduced plant growth. Enterobacter aerogenes, Pseudomonas marginalis, Acinetobacter sp., and Klebsiella pneumoniae suppressed the colonization by R. meliloti of roots grown on agar and reduced nodulation by R. meliloti, the suppression of nodulation being statistically significant for the first three species. Bradyrhizobium sp. and "Sarcina lutea" did not suppress root colonization nor nodulation by R. meliloti. The doubling times in the rhizosphere for E. aerogenes, P. marginalis, Acinetobacter sp., and K. pneumoniae were less and the doubling times for Bradyrhizobium sp. and "S. lutea" were greater than the doubling time of R. meliloti. Under the same conditions, Arthrobacter citreus injured alfalfa roots. We suggest that competition by soil bacteria reduces nodulation by rhizobia in soil and that the extent of inhibition is related to the growth rates of the rhizosphere bacteria. PMID:16347173

  6. Repeated sequences similar to insertion elements clustered around the nif region of the Rhizobium japonicum genome.

    Kaluza, K; Hahn, M; Hennecke, H

    1985-05-01

    Two different repeated sequences (RSs) were discovered in the Rhizobium japonicum genome: RSRj alpha is 1126 base pairs long and is repeated 12 times; RSRj beta is approximately 950 base pairs long and is repeated at least 6 times. Their arrangement in root nodule bacteroid DNA is the same as in DNA from bacteria grown in culture. Deletion analysis showed that many copies of alpha and beta are clustered around the nitrogenase genes nifDK and nifH, or, in general, they are found within a genomic region harboring genes that are nonessential for growth. One copy each of alpha and beta are located upstream of nifDK and are adjacent to each other. Neither of them, however, is involved in the expression of nifDK. Nucleotide sequence analysis of three copies of RS alpha revealed many characteristics of procaryotic insertion sequence elements: potential inverted repeats at their ends, potential target site duplication, and large open reading frames. Despite this, their genomic positions appear to be stable. One possible function of these RSs is in deletion formation probably via recombination between them. PMID:2985537

  7. Versatile properties of an exopolysaccharide R-PS18 produced by Rhizobium sp. PRIM-18.

    Priyanka, P; Arun, A B; Ashwini, P; Rekha, P D

    2015-08-01

    Exopolysaccharides (EPS) produced by bacteria have attracted scientific and industrial attention due to their multifunctional properties and relatively easier production. In this study, an EPS viz., R-PS18 produced by Rhizobium sp. PRIM-18 was characterized and its functional properties were assessed. Cell proliferative and in vitro wound healing activities of the EPS were established using human dermal fibroblast (HDF) cells. The isolate produced 2.1 g L(-1) purified EPS (molecular weight 9.33×10(6) Da) comprising of glucose, galactose, and mannose (6.1:1.8:1). Viscosity of 0.25% solution was 23.4 mPa s (shear rate 75 s(-1)) and it showed pseudoplastic and thixotropic behavior. High emulsification, iron chelation, and superoxide scavenging abilities were also observed. Significant increase in HDF cell proliferation and wound healing in vitro was achieved by R-PS18 treatment. Sulfation of R-PS18 significantly enhanced the cell proliferative and wound healing activities. In conclusion, these findings indicate potential applications of R-PS18. PMID:25933542

  8. Production of Rhizobium Inoculants for Lupinus nootkatensis on Nutrient-Supplemented Pumice.

    Einarsson, S; Gudmundsson, J; Sverrisson, H; Kristjansson, J K; Runolfsson, S

    1993-11-01

    The use of the legume Lupinus nootkatensis as a pioneer plant to fight soil erosion and to reclaim eroded soils in Iceland has been under development for a few years. Production of a robust, low-cost bacterial inoculant was therefore a prerequisite for the extended use of this plant. Volcanic pumice is a naturally expanded mineral which is available in vast amounts in Iceland. It was tested as a carrier for solid fermentation of Rhizobium lupini. Nutrient-supplemented pumice containing a small percentage of peat and diatomaceous earth and kept in sterile plastic bags promoted good growth of the bacteria. Viable-colony counts remained stable at 10 to 10/g for at least 35 weeks when the carrier was stored at 22 degrees C. The pumice-based inoculant had good storage and handling properties and could be mixed directly with the seeds during the sowing process. When seeds of L. nootkatensis were sown manually into nutrient-poor eroded sandy soils, about 56% of the first-year plants were successfully nodulated. PMID:16349083

  9. Role of nickel in membrane-bound hydrogenase and nickel metabolism in Rhizobium japonicum

    The membrane-bound hydrogenase of Rhizobium japonicum requires nickel for activity. Radioactive 63Ni co-migrates with hydrogenase activity in native gel systems and co-elutes with purified hydrogenase form an affinity matrix column. A simplified scheme for the purification of hydrogenase has been developed and constitutes the first report of the aerobic purification of this enzyme from R. japonicum. The aerobic purification utilizes the general affinity matrix. Reactive Red 120-agarose and results in higher specific activity and yield of enzyme than previously reported. The stability of aerobically purified hydrogenase to oxygen is substantially greater than that reported for anaerobically isolated enzyme. Reduction of the aerobically purified enzyme in the presence of oxygen, however, results in the rapid loss of activity. R. japonicum cells accumulate nickel during heterotrophic growth and as non-growing cells. The hydrogenase constitutive mutant SR470 accumulates substantially greater amounts of nickel under both conditions. Kinetic studies indicate that the nickel uptake system in the hydrogenase constitutive mutant SR470 is upregulated relative to SRwt cells. The uptake system is specific for nickel, although a 10-fold excess (relative to nickel) of copper or zinc inhibits nickel uptake. The nickel uptake system appears to require energy. Under nickel-free conditions hydrogenase protein is not synthesized as determined by cross-reactivity with antibodies directed against hydrogenase, indicating that nickel regulates the formation of the enzyme as well as being a constituent of the active protein

  10. Rhizobium sp. effects, irradiated with ultraviolet and gamma rays, on nodulation of P. vulgaris (L.) bean

    Indigenous isolates of Rhizobium sp. from the root nodules of bean were selected. There of these isolates and a R. leguminosarum biovar phaseoli (SEMIA 4064) strain, used as a reference, were irradiated with ultraviolet (UV) light and gamma-Rays (γ-R). The relations between survival and fluence of UV, and survival and absorbed dose of γ-R were linear for the strain of reference. The D37 values, for this rhizobial strain were 43 j.m-2 for the UV-treatment, and 32 Gy for the γ-rays treatment. Through a greenhouse experiment the irradiated isolates were inoculated on bean seedlings (P. vulgaris L, Variety IPA-8), in an attempt to evaluate sensitivity of the host-plants and possible effects on their nodulation. Significant differences were observed only for root dry matter yield. For all the other evaluated parameters variance was of such magnitude that it was not possible to detect significance of the effects. The isolates tested showed difference in responses to nodulation, due to the effects of irradiations. The host plant (IPA-8) seemed to be sensitive to the possible modifications in the irradiated isolates. (author). 10 refs, 6 figs, 1 tab

  11. Osmotic control of glycine betaine biosynthesis and degradation in Rhizobium meliloti

    Intracellular accumulation of glycine betaine has been shown to confer an enhanced level of osmotic stress tolerance in Rhizobium meliloti. In this study, the authors used a physiological approach to investigate the mechanism by which glycine betaine is accumulated in osmotically stressed R. meliloti. Results from growth experiments, 14C labeling of intermediates, and enzyme activity assays are presented. The results provide evidence for the pathway of biosynthesis and degradation of glycine betaine and the osmotic effects on this pathway. High osmolarity in the medium decreased the activities of the enzymes involved in the degradation of glycine betaine but not those of enzymes that lead to its biosynthesis from choline. Thus, the concentration of the osmoprotectant glycine betaine is increased in stressed cells. This report demonstrates the ability of the osmolarity of the growth medium to regulate the use of glycine betaine as a carbon and nitrogen source or as an osmoprotectant. The mechanisms of osmoregulation in R. meliloti and Escherichia coli are compared

  12. Increased effectiveness of competitive rhizobium strains upon inoculation of Cajanus cajan

    A field study was conducted in lysimeters containing 15N-enriched soil to determine the effects of four competitive rhizobium strains upon yield parameters of pigeon peas (Cajanus cajan). The greatest differences observed were in seed yields; strain P132 effected the highest seed yield (121 +/- 20 g per plant), and the control strain (indigenous rhizobia) effected the lowest yield (43.9 +/- 8 g per plant). With the exception of seeds and pods, the dry matter weights were not different. Although there appeared to be no effect by inoculum strains on the fractional content of N derived from biological nitrogen fixation when the total plant biomass was considered, strains P132 and 401 partitioned more of the N derived from fixation into seeds and leaves than did the other strains. Because the seeds comprised the major portion of plant N, more total N and more N derived from biological nitrogen fixation (about half of total N) were found in plants inoculated with P132, whereas the smallest amount was found in the uninoculated controls. P132 was also the best competitor with respect to indigenous rhizobia and accounted for all of the nodules found on the plants in which it was inoculated

  13. Sobrevivência e nodulação do Rhizobium tropici em sementes de feijão tratadas com fungicidas

    Araújo Ademir Sérgio Ferreira de

    2006-01-01

    Full Text Available O objetivo deste trabalho foi avaliar a sobrevivência e a capacidade de nodulação do Rhizobium tropici em sementes de feijão tratadas com fungicidas. O estudo foi realizado em laboratório e em casa de vegetação. Sementes de feijão (Phaseolus vulgaris foram tratadas com seis diferentes fungicidas e inoculadas com Rhizobium tropici estirpe CIAT 899. A sobrevivência do Rhizobium nas sementes foi avaliada no tempo 0 e 24 horas após o tratamento com fungicidas e a inoculação, utilizando o método do número mais provável (NMP. A nodulação do feijão, em plantio realizado no tempo 0 e 24 horas após o tratamento com fungicidas, e a inoculação foram avaliadas em solo com população estabelecida de Rhizobium nativo aos trinta dias após a emergência das plantas. A sobrevivência do Rhizobium inoculado nas sementes foi prejudicada pela aplicação dos fungicidas avaliados. A nodulação do feijoeiro foi reduzida pela aplicação dos fungicidas, quando o plantio foi realizado 24 horas após o tratamento das sementes. Entretanto, foram encontrados nódulos em todos os tratamentos, evidenciando que houve nodulação do Rhizobium nativo do solo.

  14. Genomic basis of broad host range and environmental adaptability of Rhizobium tropici CIAT 899 and Rhizobium sp. PRF 81 which are used in inoculants for common bean (Phaseolus vulgaris L.

    Ormeño-Orrillo Ernesto

    2012-12-01

    Full Text Available Abstract Background Rhizobium tropici CIAT 899 and Rhizobium sp. PRF 81 are α-Proteobacteria that establish nitrogen-fixing symbioses with a range of legume hosts. These strains are broadly used in commercial inoculants for application to common bean (Phaseolus vulgaris in South America and Africa. Both strains display intrinsic resistance to several abiotic stressful conditions such as low soil pH and high temperatures, which are common in tropical environments, and to several antimicrobials, including pesticides. The genetic determinants of these interesting characteristics remain largely unknown. Results Genome sequencing revealed that CIAT 899 and PRF 81 share a highly-conserved symbiotic plasmid (pSym that is present also in Rhizobium leucaenae CFN 299, a rhizobium displaying a similar host range. This pSym seems to have arisen by a co-integration event between two replicons. Remarkably, three distinct nodA genes were found in the pSym, a characteristic that may contribute to the broad host range of these rhizobia. Genes for biosynthesis and modulation of plant-hormone levels were also identified in the pSym. Analysis of genes involved in stress response showed that CIAT 899 and PRF 81 are well equipped to cope with low pH, high temperatures and also with oxidative and osmotic stresses. Interestingly, the genomes of CIAT 899 and PRF 81 had large numbers of genes encoding drug-efflux systems, which may explain their high resistance to antimicrobials. Genome analysis also revealed a wide array of traits that may allow these strains to be successful rhizosphere colonizers, including surface polysaccharides, uptake transporters and catabolic enzymes for nutrients, diverse iron-acquisition systems, cell wall-degrading enzymes, type I and IV pili, and novel T1SS and T5SS secreted adhesins. Conclusions Availability of the complete genome sequences of CIAT 899 and PRF 81 may be exploited in further efforts to understand the interaction of tropical rhizobia with common bean and other legume hosts.

  15. CERBERUS, a novel U-box protein containing WD-40 repeats, is required for formation of the infection thread and nodule development in the legume-Rhizobium symbiosis

    Yano, Koji; Shibata, Satoshi; Chen, Wen-Li; Sato, Shusei; Kaneko, Takakazu; Jurkiewicz, Anna; Sandal, Niels; Banba, Mari; Imaizumi-Anraku, Haruko; Kojima, Tomoko; Ohtomo, Ryo; Szczyglowski, Krzysztof; Stougaard, Jens; Tabata, Satoshi; Hayashi, Makoto; Kouchi, Hiroshi; Umehara, Yosuke

    2009-01-01

    Endosymbiotic infection of legume plants by Rhizobium bacteria is initiated through infection threads (ITs) which are initiated within and penetrate from root hairs and deliver the endosymbionts into nodule cells. Despite recent progress in understanding the mutual recognition and early symbiotic...... nodule primordia and the infected zone of mature nodules. In cerberus mutants, Rhizobium colonized curled root hair tips, but hardly penetrated into root hair cells. The occasional ITs that were formed inside the root hair cells were mostly arrested within the epidermal cell layer. Nodule organogenesis...

  16. Characterization of the gene encoding nitrite reductase and the physiological consequences of its expression in the nondenitrifying Rhizobium "hedysari" strain HCNT1.

    Toffanin, A; WU, Q; Maskus, M; Caselia, S; Abruña, H. D.; Shapleigh, J P

    1996-01-01

    Rhizobium "hedysari" HCNT1 is an unclassified rhizobium which contains a nitric oxide-producing nitrite reductase but is apparently incapable of coupling the reduction of nitrite to energy conservation. The gene encoding the nitrite reductase, nirK, has been cloned and sequenced and was found to encode a protein closely related to the copper-containing family of nitrite reductases. Unlike other members of this family, nirK expression in HCNT1 is not dependent on the presence of nitrogen oxide...

  17. Rapport final de la Collaboration CERN-CNRS pour la construction du LHC Accord Technique d'Exécution No 2 Cryostats et assemblage des sections droites courtes (SSS) du LHC

    Bergot, JB; Poncet, A; Rohmig, P; Roy, E; Vincent, D

    2006-01-01

    Depuis 1995 et suite à la signature du protocole de Collaboration, le CERN, le CEA et le CNRS ont étroitement collaboré dans le cadre de la contribution exceptionnelle de la France à la construction du LHC. Pour le CNRS, l'Institut de Physique Nucléaire d'Orsay a pris en charge deux Accords Techniques d'Exécution. Le premier concerne la conception et l'assemblage des Sections Droites Courtes de la machine, et le deuxième, l'étalonnage des thermomètres cryogéniques du LHC. Dans le cadre de l'Accord Technique d'Exécution N°2, le Bureau d'Etudes de la Division Accélérateur de l'IPNO et le groupe AT-CRI du CERN ont travaillé de concert pour mener à bien la conception des SSS (Short Straight Section) et de tous les équipements nécessaires à l'assemblage. Ce rapport a donc pour objectif de dresser, en termes d'historique, d'organisation, de résultats quantitatifs et qualitatifs et de moyens mis en ?uvre, un tableau aussi complet que possible du déroulement de cette Collaboration entre le CERN e...

  18. Bourges (Cher), ZAC Avaricum. Évolution d'un quartier urbain de Bourges du 1er s. ap. J.-C. jusqu'à nos jours, Rapport final d'opération de fouille préventive, volume 1 à 4 : Volume 1 à 4 : texte, plans et études spécialisées.

    Fondrillon, Mélanie; Marot, Emmanuel; Troadec, Jacques

    2012-01-01

    Ces quatre volumes sont issus du rapport final d'opération de fouille préventive qui présente les découvertes archéologiques faites sur le site de la ZAC Avaricum à Bourges (Cher, France). Le premier concerne la présentation diachronique de la stratification du site et des structures. Le deuxième porte sur les plans. Les troisième et quatrième concernent les différentes études de spécialistes.

  19. Mise en relation de la qualité des produits et des paysages : enseignements issus de l'analyse comparée entre le fromage AOC Saint Nectaire et la marque viande bovine du parc naturel régional du Morvan : rapport final

    Dobremez, L.; Aznar, O.; Candau, J.; Ernoult, C.; Ginelli, L.; Guerreiro, F.; Landré, F.; Michelin, Y.; Ménadier, L.; Perret, E.; Rapey, H.; Vollet, D.

    2008-01-01

    / L'objectif de cette étude est de caractériser les liens entre des paysages et des produits dont la qualité est certifiée par un cahier des charges. Sur deux terrains et produits, le fromage AOC Saint Nectaire et la marque viande bovine du parc naturel régional du Morvan, différentes approches (géographique, agronomique, sociologique et économique) ont été mises en ½uvre et croisées afin d'identifier les éléments matériels caractéristiques du paysage et ceux liés à la représentation des acte...

  20. Revision of the taxonomic status of the species Rhizobium lupini and reclassification as Bradyrhizobium lupini comb. nov.

    Peix, Alvaro; Ramírez-Bahena, Martha Helena; Flores-Félix, José David; Alonso de la Vega, Pablo; Rivas, Raúl; Mateos, Pedro F; Igual, José M; Martínez-Molina, Eustoquio; Trujillo, Martha E; Velázquez, Encarna

    2015-04-01

    The species Rhizobium lupini was isolated from Lupinus nodules and included in the Approved Lists of Bacterial Names in 1980. Nevertheless, on the basis of the analysis of the type strain of this species available in DSMZ, DSM 30140(T), whose 16S rRNA gene was identical to that of the type strain of Bradyrhizobium japonicum , R. lupini was considered a later synonym of this species. In this study we confirmed that the strain DSM 30140(T) belongs to the species B. japonicum , but also that it cannot be the original strain of R. lupini because this species effectively nodulated Lupinus whereas strain DSM 30140(T) was able to nodulate soybean but not Lupinus. Since the original type strain of R. lupini was deposited into the USDA collection by L. W. Erdman under the accession number USDA 3051(T) we analysed the taxonomic status of this strain showing that although it belongs to the genus Bradyrhizobium instead of genus Rhizobium , it is phylogenetically distant from B. japonicum and closely related to Bradyrhizobium canariense . The type strains R. lupini USDA 3051(T) and B. canariense BTA-1(T) share 16S rRNA, recA and glnII gene sequences with similarities of 99.8%, 96.5% and 97.1%, respectively. They presented a DNA-DNA hybridization value of 36% and also differed in phenotypic characteristics and slightly in the proportions of some fatty acids. Therefore we propose the reclassification of the species Rhizobium lupini as Bradyrhizobium lupini comb. nov. The type strain is USDA 3051(T) (?=?CECT 8630(T)?=?LMG 28514(T)). PMID:25609676

  1. Legume-bacterium (Rhizobium Association-Symbiosis, A Marriage of Convenience, Necessary Evil or Bacterium Taken Hostage by the Legume

    F. Azam

    2001-01-01

    Full Text Available Nitrogen (N is the key nutrient element, limiting crop production under most situations. A major reason for insufficient N supplies being its presence in soil in organic forms which must be mineralized before being used by the plants. However, leguminous plants are equipped with the facility to acquire a major portion of N directly from atmospheric N2 through bacterial fixation (reduction. The bacteria (Rhizobium spp reside inside the special structures on plant roots i.e., nodules and reduce atmospheric N at the expense of C supplied by the plant. This paper presents an analysis of the nature of association between the legume and bacterium.

  2. [Signaling Systems of Rhizobia (Rhizobiaceae) and Leguminous Plants (Fabaceae) upon the Formation of a Legume-Rhizobium Symbiosis (Review)].

    Glyan'ko, A K

    2015-01-01

    Data from the literature and our own data on the participation and interrelation of bacterial signaling Nod-factors and components of the calcium, NADPH-oxidase, and NO-synthase signaling systems of a plant at the preinfection and infectious stages of the formation of a legume-rhizobium symbiosis are summarized in this review. The physiological role of Nod-factors, reactive oxygen species (ROS), calcium (Ca2+), NADPH-oxidase, nitric oxide (NO), and their cross influence on the processes determining the formation of symbiotic structures on the roots of the host plant is discussed. PMID:26596081

  3. Poly-3-Hydroxybutyrate Degradation in Rhizobium (Sinorhizobium) meliloti: Isolation and Characterization of a Gene Encoding 3-Hydroxybutyrate Dehydrogenase

    Aneja, P.; Charles, T.C.

    1999-01-01

    We have cloned and sequenced the 3-hydroxybutyrate dehydrogenase-encoding gene (bdhA) from Rhizobium (Sinorhizobium) meliloti. The gene has an open reading frame of 777 bp that encodes a polypeptide of 258 amino acid residues (molecular weight 27,177, pI 6.07). The R. meliloti Bdh protein exhibits features common to members of the short-chain alcohol dehydrogenase superfamily. bdhA is the first gene transcribed in an operon that also includes xdhA, encoding xanthine oxidase/dehydrogenase. Tra...

  4. Role of BacA in Lipopolysaccharide Synthesis, Peptide Transport, and Nodulation by Rhizobium sp. Strain NGR234?

    Ardissone, Silvia; Kobayashi, Hajime; Kambara, Kumiko; Rummel, Coralie; Noel, K. Dale; Walker, Graham C.; Broughton, William J; Deakin, William J.

    2011-01-01

    BacA of Sinorhizobium meliloti plays an essential role in the establishment of nitrogen-fixing symbioses with Medicago plants, where it is involved in peptide import and in the addition of very-long-chain fatty acids (VLCFA) to lipid A of lipopolysaccharide (LPS). We investigated the role of BacA in Rhizobium species strain NGR234 by mutating the bacA gene. In the NGR234 bacA mutant, peptide import was impaired, but no effect on VLCFA addition was observed. More importantly, the symbiotic abi...

  5. Análisis genómico y funcional de los sistemas de Quorum Sensing en Rhizobium leguminosarum

    Sanchez Cañizares, Carmen

    2013-01-01

    Rhizobium leguminosarum (Rl) es una alfa-proteobacteria capaz de establecer una simbiosis diazotrófica con distintas leguminosas. A pesar de la importancia de esta simbiosis en el balance global del ciclo del nitrógeno, muy pocos genomas de rhizobios han sido secuenciados, que aporten nuevos conocimientos relacionados con las características genéticas que contribuyen a importantes procesos simbióticos. Únicamente tres secuencias completas de Rl han sido publicadas: Rl bv. viciae 3841 y dos ge...

  6. Interacción de tsukamurella paurometabola c-924 con rhizobium leguminosarum biovar phaseoli cfh en el cultivo de frijol

    Marin Bruzos, Marieta; Mena Campos, Jesús; Chaveli Chaves, Pavel; Morán Valdivia, Rolando; Pimentel Vásquez, Eulogio

    2014-01-01

    En el estudio se evaluaron, mediante análisis de los parámetros fenológicos de las plantas, la interacción de Tsukamurella paurometabola C-924 con Rhizobium leguminosarum biovar phaseoli CFH en el cultivo de frijol. Se emplearon cuatro tratamientos: plantas sin inocular (control), inoculadas con T. paurometabola C-924, inoculadas con R. leguminosarum biovar phaseoli CFH e inoculadas con ambascepas. Se observaron diferencias significativas (P < 0.01) en los porcentajes de germinación de las...

  7. Response of chickpea (cicer arietinum L.) to various levels of phosphorus and rhizobium inoculation under rainfed condition

    A field experiment was conducted to evaluate the effect of phosphorus (P) levels and Rhizobium inoculation on yield-components and grain-yield of (chickpea c.v. NIFA-88) under rain fed conditions at Arid Zone Research Institute, Dera Ismail Khan, during 2003- 04. The treatments consisted of P levels; 0, 30, 60 and 90 kg ha-I, with and without inoculum. A basal dose of 20 kg ha-l nitrogen was applied just before sowing, at the time of seedbed preparation. The experiment was laid out according to the randomized complete block design, with three replications. The results showed significant variation in number of pods per plant, 1000 seed weight and grain yield, with the application of P and Rhizobium inoculum. The maximum number of pods per plant (25.00) was recorded in the plots receiving 60 kg P/sub 2/ O/sub 5/ h a/sup -l/ plus inoculum, but was statistically at par with the pods produced by the treatment of 90 kg P/sub 2/ O/sub 5/ ha-l plus inoculum (24.67). Phosphorus levels plus inoculum gave 11.87 percent increased number of pods per plant over mere P levels. Similarly, the maximum 1000 seed weight of 197.0 g was recorded at the rate 90 and 60 kg P/sub 2/O/sub 5/ ha-1 plus inoculum and 90 kg P/sub 2/ O/sub 5/ ha-l alone. The highest grain-yield of 1,317 kg ha/sup -l/ was obtained from the treatments where P was applied at the rate 90 and 60 kg ha-I with inoculum. The grain yield was increased 8.54 percent when P levels were applied with inoculums, as compared to Palone, on average basis. Hence, it can be concluded from the study that (I) Rhizobium inoculum application alone can increase yield, and (II) 60 kg P/sub 2/ O/sub 5/ ha-l is the most economical dose to be used with Rhizobium inoculum for obtaining higher grain-yield of chickpea. (author)

  8. Proteomic profiling of Rhizobium tropici PRF 81: identification of conserved and specific responses to heat stress

    Gomes Douglas

    2012-05-01

    Full Text Available Abstract Background Rhizobium tropici strain PRF 81 (= SEMIA 4080 has been used in commercial inoculants for application to common-bean crops in Brazil since 1998, due to its high efficiency in fixing nitrogen, competitiveness against indigenous rhizobial populations and capacity to adapt to stressful tropical conditions, representing a key alternative to application of N-fertilizers. The objective of our study was to obtain an overview of adaptive responses to heat stress of strain PRF 81, by analyzing differentially expressed proteins when the bacterium is grown at 28°C and 35°C. Results Two-dimensional gel electrophoresis (2DE revealed up-regulation of fifty-nine spots that were identified by MALDI-TOF/TOF-TOF. Differentially expressed proteins were associated with the functional COG categories of metabolism, cellular processes and signaling, information storage and processing. Among the up-regulated proteins, we found some related to conserved heat responses, such as molecular chaperones DnaK and GroEL, and other related proteins, such as translation factors EF-Tu, EF-G, EF-Ts and IF2. Interestingly, several oxidative stress-responsive proteins were also up-regulated, and these results reveal the diversity of adaptation mechanisms presented by this thermotolerant strain, suggesting a cross-talk between heat and oxidative stresses. Conclusions Our data provide valuable protein-expression information relevant to the ongoing genome sequencing of strain PRF 81, and contributes to our still-poor knowledge of the molecular determinants of the thermotolerance exhibited by R. tropici species.

  9. Production of Poly &beta-Hydroxybutyric Acid (PHB by Rhizobium elti and Pseudomonas stutzeri

    Elsayed B. Belal

    2013-11-01

    Full Text Available The amount of chemosynthetic plastic waste increases every year and exact time for its degradation is unknown. Two poly &beta-Hydroxybutyric producing bacteria from different microbial sources were isolated and characterized for their morphological, biochemical properties. Based on their 16S rDNA, they were identified as Rhizobium elti E1 and Pseudomonas stutzeri E114. The bacterial strains were screened for PHB production and compared for the intensity of fluorescence using Nile red staining methods. PHB production conditions were optimized with different carbon and nitrogen sources, the highest PHB production was observed with mannitol, sucrose and ammonium sulphate by R. elti and P. stutzeri, respectively. Regarding incubation time as well as temperature and pH, optimum PHB production conditions were 48 h, 30C and 7, respectively. R. elti P. stutzeri are capable of accumulating appreciable levels of PHB from glucose, xylose, lactose, whey, molasses, sugar cane bagasse, rice straw hydroysate when 2% from all substrates were used an alternative carbon for the PHB production. Ammonium sulphate was the best nitrogen source. C/N ratio was also one of the factors that affected the production of PHB. The ratio of C/N that reaches 20:1 was considered the best ratio to produce the highest production of PHB. The highest yield of PHB was done by P. stutzeri more than R. elti. The present study provide the useful data about the optimized conditions for PHB production by R. elti and P. stutzeri that can be utilized for industrial production of PHB, a fast emerging alternative of non biodegradable plastics.

  10. Adaptation of Rhizobium leguminosarum to pea, alfalfa and sugar beet rhizospheres investigated by comparative transcriptomics

    2011-01-01

    Background The rhizosphere is the microbe-rich zone around plant roots and is a key determinant of the biosphere's productivity. Comparative transcriptomics was used to investigate general and plant-specific adaptations during rhizosphere colonization. Rhizobium leguminosarum biovar viciae was grown in the rhizospheres of pea (its legume nodulation host), alfalfa (a non-host legume) and sugar beet (non-legume). Gene expression data were compared to metabolic and transportome maps to understand adaptation to the rhizosphere. Results Carbon metabolism was dominated by organic acids, with a strong bias towards aromatic amino acids, C1 and C2 compounds. This was confirmed by induction of the glyoxylate cycle required for C2 metabolism and gluconeogenesis in all rhizospheres. Gluconeogenesis is repressed in R. leguminosarum by sugars, suggesting that although numerous sugar and putative complex carbohydrate transport systems are induced in the rhizosphere, they are less important carbon sources than organic acids. A common core of rhizosphere-induced genes was identified, of which 66% are of unknown function. Many genes were induced in the rhizosphere of the legumes, but not sugar beet, and several were plant specific. The plasmid pRL8 can be considered pea rhizosphere specific, enabling adaptation of R. leguminosarum to its host. Mutation of many of the up-regulated genes reduced competitiveness for pea rhizosphere colonization, while two genes specifically up-regulated in the pea rhizosphere reduced colonization of the pea but not alfalfa rhizosphere. Conclusions Comparative transcriptome analysis has enabled differentiation between factors conserved across plants for rhizosphere colonization as well as identification of exquisite specific adaptation to host plants. PMID:22018401

  11. Competition among rhizobium species for nodulation of Leucaena leucocephala in two tropical soils

    Moawad, H.; Bohlool, B.B.

    1984-07-01

    The successful nodulation of legumes by a Rhizobium strain is determined by the competitve ability of that strain against the mixture of other native and inoculant rhizobia. Competition among six Leucaena rhizobial strains in single and multistrain inoculants were studied. Field inoculation trials were conducted in an oxisol and a mollisol soil, both of which contained indigenous Leucaena-nodulating rhizobia. Strain-specific fluorescent antibodies were used for the identification of the strains in Leucaena nodules. Mixtures of three recommended inoculum strains for Leucaena species (TAL82, TAL582, and TAL1145) were used in peat-based inocula either alone or with one of the three other strains isolated from the sites, B213, B214, and B215. Each of these latter three strains was also used as single-strain inocula to study their competition with the native rhizobia in the two soil systems. In the oxisol soil, strains B213 and B215, when used as single-strain inocula, outcompeted the native rhizobia and formed 92 and 62% of the nodules, respectively. Strain B214 was the least competitive in oxisol soil, where it formed 30% of the nodules, and the best in mollisol soil, where it formed 70% of the nodules. The most successful competitor for nodulation in multistrain inocula was strain TAL1145, which outcompeted native and other inoculum Leucaena rhizobia is both soils. None of the strains in single or multistrain inoculants was capable of completely overcoming the resident rhizobia, which formed 4 to 70% of the total nodules in oxisol soil and 12 to 72% in mollisol soil. No strong relationship was detected between the size of the rhizosphere population of a strain and its successful occupation of nodules. 24 references.

  12. Competition Among Rhizobium spp. for Nodulation of Leucaena leucocephala in Two Tropical Soils.

    Moawad, H; Bohlool, B B

    1984-07-01

    The successful nodulation of legumes by a Rhizobium strain is determined by the competitive ability of that strain against the mixture of other native and inoculant rhizobia. Competition among six Leucaena rhizobial strains in single and multistrain inoculants were studied. Field inoculation trials were conducted in an oxisol and a mollisol soil, both of which contained indigenous Leucaena-nodulating rhizobia. Strain-specific fluorescent antibodies were used for the identification of the strains in Leucaena nodules. Mixtures of three recommended inoculum strains for Leucaena spp. (TAL82, TAL582, and TAL1145) were used in peat-based inocula either alone or with one of the three other strains isolated from the sites, B213, B214, and B215. Each of these latter three strains was also used as single-strain inocula to study their competition with the native rhizobia in the two soil systems. In the oxisol soil, strains B213 and B215, when used as single-strain inocula, outcompeted the native rhizobia and formed 92 and 62% of the nodules, respectively. Strain B214 was the least competitive in oxisol soil, where it formed 30% of the nodules, and the best in mollisol soil, where it formed 70% of the nodules. The most successful competitor for nodulation in multistrain inocula was strain TAL1145, which outcompeted native and other inoculum Leucaena rhizobia in both soils. None of the strains in single or multistrain inoculants was capable of completely overcoming the resident rhizobia, which formed 4 to 70% of the total nodules in oxisol soil and 12 to 72% in mollisol soil. No strong relationship was detected between the size of the rhizosphere population of a strain and its successful occupation of nodules. PMID:16346600

  13. Competition Among Rhizobium leguminosarum Strains for Nodulation of Lentils (Lens esculenta).

    May, S N; Bohlool, B B

    1983-03-01

    Thirty-one cultures of Rhizobium leguminosarum were screened for effectiveness (C(2)H(2) reduction) on lentils (Lens esculenta). Fluorescent antibodies prepared against three of the most effective strains (Hawaii 5-0, Nitragin 92A3, and Nitragin 128A12) exhibited a high degree of strain specificity; the antibodies reacted strongly with their homologous rhizobia in culture and with bacteroids in nodules. They did not cross-react with one another, and only weakly with 5 of the 47 other R. leguminosarum cultures tested. In competition studies in the growth chamber, whenever strain Nitragin 92A3 was included in the inoculum mixture, it consistently (but not always significantly, P = 0.05) occupied the majority of nodules on all four cultivars used. However, some degree of strain X cultivar interaction was apparent: Hawaii 5-0 was of equal competitiveness (P = 0.05) with Nitragin 92A3 on three of the varieties (Commercial, Tekoa, and Benewah), but inferior (P = 0.01) on the Chilean variety; Nitragin 92A3 completely dominated (P = 0.01) Nitragin 128A12 on all cultivars; and Hawaii 5-0 was of equal competitiveness (P = 0.05) to Nitragin 128A12 on the Chilean variety and more competitive (P = 0.01) on the commercial variety and less so on the other two varieties. In field experiments, Hawaii 5-0 proved of equal competitiveness (P = 0.01) with Nitragin 92A3 in one soil (an Inceptisol) and superior (P Oxisol). Incidence of double-strain occupancy of nodules varied from 0 to 36% in vermiculite, depending on the strains in the mixture and the host variety, and from 0 to 38% in the field, depending on the strains in the mixture and the soil type. The results suggest a close relationship between the competitiveness of a strain and its occurrence in doubly infected nodules. PMID:16346257

  14. Detection of Rhizobium meliloti cells in field soil and nodules by polymerase chain reaction.

    Watson, R J; Haitas-Crockett, C; Martin, T; Heys, R

    1995-09-01

    A genetically marked Rhizobium meliloti strain, R692, was prepared by insertion of a 1.7-kb DNA segment from Tn903 between the nifHDK and fixABC genes in the nod megaplasmid. This DNA was used as a marker, detectable by polymerase chain reaction (PCR), for the specific identification of bacteria in soil samples and alfalfa nodules. This detection technique was tested by applying different titres of the marked strain to field plots seeded with alfalfa. Samples of soil and nodules were assayed for the presence of the marker DNA fragment by PCR using primers specific to the marker sequence. The experiments revealed that the bacteria could be detected directly in soil containing about 10(3)-10(4) bacteria/g, but greater sensitivity was prevented by potent PCR inhibitors present in the samples. The titre of the bacteria in the soil decreased rapidly after inoculation, dropping about 10-fold per week. Tests of vertical location of the bacteria in soil cores showed that the bacteria were initially dispersed to a depth of 18 cm, and subsequently retained viability in the top 2-8 cm. As few as 10 marked R. meliloti per gram of soil resulted in its establishment at detectable levels in nodules. Application of about 10(4)-10(5) bacteria/g soil was sufficient to give the maximum number of nodules per plant and resulted in 70-90% occupancy by the marked strain. Limited movement of the inoculant was detected by analysis of nodules from plants adjacent to the sites where the bacteria were applied, probably by movement in water. The experiments demonstrated the advantages of PCR for the monitoring of marked microorganisms in the environment. PMID:7585359

  15. Biogeography of Rhizobium radiobacter and distribution of associated temperate phages in deep subseafloor sediments.

    Engelhardt, Tim; Sahlberg, Monika; Cypionka, Heribert; Engelen, Bert

    2013-01-01

    Bacteriophages might be the main 'predators' in the marine deep subsurface and probably have a major impact on indigenous microbial communities. To identify their function within this habitat, we have determined their abundance and distribution along the sediment columns of two continental margin and two open ocean sites that were recovered during Leg 201 of the Ocean Drilling Program. For all investigated sites, viral abundance followed the total cell numbers with a virus-to-cell ratio between 1 and 10 in the upper 100?mbsf (meters below seafloor). An increasing ratio of about 20 in deeper layers indicated an ongoing viral production in up to 11?Ma old sediments. We have used Rhizobium radiobacter as the most frequently isolated organism from the deep subsurface with a high in situ abundance to identify the frequency of associated rhizobiophages. In this study, 16S rRNA gene copies of R. radiobacter accounted for up to 5.6% of total bacterial 16S rRNA genes (average: 0.75%) as detected by quantitative PCR. A distinctive distribution was identified for R. radiobacter as indicated by a site-specific arrangement of genetically similar populations. Whole genome information of rhizobiophage RR1-A was used to generate a primer system for quantitative PCR specifically targeting the prophage antirepressor gene, indicative for temperate phages. The quantification of this gene within various sediment horizons showed a contribution of temperate phages of up to 14.3% to the total viral abundance. Thus, the high amount of temperate phages within the sediments and among all investigated isolates indicates that lysogeny is the main viral proliferation mode in deep subsurface populations. PMID:22855213

  16. Reactive Oxygen Species and Nitric Oxide Control Early Steps of the Legume – Rhizobium Symbiotic Interaction

    Damiani, Isabelle; Pauly, Nicolas; Puppo, Alain; Brouquisse, Renaud; Boscari, Alexandre

    2016-01-01

    The symbiotic interaction between legumes and nitrogen-fixing rhizobium bacteria leads to the formation of a new organ, the nodule. Early steps of the interaction are characterized by the production of bacterial Nod factors, the reorientation of root-hair tip growth, the formation of an infection thread (IT) in the root hair, and the induction of cell division in inner cortical cells of the root, leading to a nodule primordium formation. Reactive oxygen species (ROS) and nitric oxide (NO) have been detected in early steps of the interaction. ROS/NO are determinant signals to arbitrate the specificity of this mutualistic association and modifications in their content impair the development of the symbiotic association. The decrease of ROS level prevents root hair curling and ITs formation, and that of NO conducts to delayed nodule formation. In root hairs, NADPH oxidases were shown to produce ROS which could be involved in the hair tip growth process. The use of enzyme inhibitors suggests that nitrate reductase and NO synthase-like enzymes are the main route for NO production during the early steps of the interaction. Transcriptomic analyses point to the involvement of ROS and NO in the success of the infection process, the induction of early nodulin gene expression, and the repression of plant defense, thereby favoring the establishment of the symbiosis. The occurrence of an interplay between ROS and NO was further supported by the finding of both S-sulfenylated and S-nitrosylated proteins during early symbiotic interaction, linking ROS/NO production to a redox-based regulation of the symbiotic process. PMID:27092165

  17. Rhizobium meliloti mutants that overproduce the R. meliloti acidic Calcofluor-binding exopolysaccharide

    The acidic Calcofluor-binding exopolysaccharide of Rhizobium meliloti Rm1021 plays one or more critical roles in nodule invasion and possible in nodule development. Two loci, exoR and exoS, that effect the regulation of synthesis of this exopolysaccharide were identified by screening for derivatives of strain Rm1021 that formed mucoid colonies that fluoresced extremely brightly under UV light when grown on medium containing Calcofluor. The exopolysaccharide produced in large quantities by the exoR95::Tn5 and exoS96::Tn5 strains was indistinguishable from that produced by the parental strain Rm1021, and its synthesis required the function of at least the exoA, exoB, and exoF genes. Both the exoR and exoS loci were located on the chromosome, and the exo96::Tn5 mutation was 84% linked to the trp-33 mutation by ΦM12 transduction. Synthesis of the Calcofluor-binding exopolysaccharide by strain Rm1021 was greatly stimulated by starvation for ammonia. In contrast, the exoR95::Tn5 mutant produced high levels of exopolysaccharide regardless of the presence or absence of ammonia in the medium. The exoS96::Tn5 mutant produced elevated amounts of exopolysaccharide in the presence of ammonia, but higher amounts were observed after starvation for ammonia. The presence of either mutation increased the level of expression of exoF::TnphoA and exoP::TnphoA fusions. Analyses of results obtained when alfalfa seedlings were inoculated with the exoR95::Tn5 strain indicated that the mutant strain could not invade nodules. However, pseudorevertants that retained the original exoR95::Tn5 mutant but acquired unlinked suppressors so that they produced an approximately normal amount of exopolysaccharide were able to invade nodules and fix nitrogen

  18. Reactive Oxygen Species and Nitric Oxide Control Early Steps of the Legume - Rhizobium Symbiotic Interaction.

    Damiani, Isabelle; Pauly, Nicolas; Puppo, Alain; Brouquisse, Renaud; Boscari, Alexandre

    2016-01-01

    The symbiotic interaction between legumes and nitrogen-fixing rhizobium bacteria leads to the formation of a new organ, the nodule. Early steps of the interaction are characterized by the production of bacterial Nod factors, the reorientation of root-hair tip growth, the formation of an infection thread (IT) in the root hair, and the induction of cell division in inner cortical cells of the root, leading to a nodule primordium formation. Reactive oxygen species (ROS) and nitric oxide (NO) have been detected in early steps of the interaction. ROS/NO are determinant signals to arbitrate the specificity of this mutualistic association and modifications in their content impair the development of the symbiotic association. The decrease of ROS level prevents root hair curling and ITs formation, and that of NO conducts to delayed nodule formation. In root hairs, NADPH oxidases were shown to produce ROS which could be involved in the hair tip growth process. The use of enzyme inhibitors suggests that nitrate reductase and NO synthase-like enzymes are the main route for NO production during the early steps of the interaction. Transcriptomic analyses point to the involvement of ROS and NO in the success of the infection process, the induction of early nodulin gene expression, and the repression of plant defense, thereby favoring the establishment of the symbiosis. The occurrence of an interplay between ROS and NO was further supported by the finding of both S-sulfenylated and S-nitrosylated proteins during early symbiotic interaction, linking ROS/NO production to a redox-based regulation of the symbiotic process. PMID:27092165

  19. Regulation of nod factor sulphation genes in Rhizobium tropici CIAT899.

    Manyani, H; Sousa, C; Soria Díaz, M E; Gil-Serrano, A; Megías, M

    2001-06-01

    Rhizobium tropici CIAT899 is a tropical symbiont able to nodulate various legumes such as Leucaena, Phaseolus, and Macroptilium. Broad host range of this species is related to its Nod factors wide spectrum. R. tropici contains Nod factors sulphation nod genes, nodHPQ genes, which control nodulation efficiency in Leucaena. To study nodHPQ regulation, we carried out different interposon insertions in its upstream region. One of these generated interruptions, nodI mutant produced nonsulphated Nod factors suggesting a possible dependence of these genes on nodI upstream region. Moreover, analysis results of lacZ transcriptional fusions with these genes in symbiotic plasmid showed dependence of these genes on NodD protein. In order to determine nodHPQ organization, we studied the effect of interposon insertion upstream of each lacZ transcriptional fusion, and the data obtained was used to indicate that nodHPQ belong to the nodABCSUIJ operon. However, comparison between nodP::lacZ beta-galactosidase activity in the symbiotic plasmid and in the pHM500 plasmid (containing nodHPQ genes) suggested constitutive expression in free living, and flavonoid inducible expression in symbiotic conditions. Constitutive nodHPQ expression may play a role in bacterial house-keeping metabolism. On the other hand, the transference of R. tropici nodHPQ genes to other rhizobia that do not present sulphated substitutions demonstrated that NodH protein sulphotransference is specific to C6 at the reducing end. PMID:11467733

  20. Biological nitrogen fixation by Rhizobium sp. native gliricidia (Gliricidia sepium [Jacq.] Kunth ex Walp. under greenhouse conditions

    Milian Mindiola Pablo Ernesto

    2011-12-01

    Full Text Available

    An experiment was conducted under greenhouse conditions in order to evaluate the association and biological nitrogen fixation (BNF, six native strains of Rhizobium sp isolated from nodules gliricidia and a commercial strain (Rhizobiolc. Suspensions of 106 and 108 cells/mL for each of the strains studied and applied in two separate trials: the first with seeds and the second with seedlings 35 days of age gliricidia. In the seed test is calculated the cumulative percentage of germination for 7 days. In both trials after 42 days in seeds and seedlings 52 days in length was measured and stem diameter, leaf number, dry weight of aerial parts, number of nodules/plant and percentage of nitrogen. All treatments stimulated germination, growth and BNF, being better in the native strains at a concentration of 108 cells/mL, compared with the commercial strain and the control. These results indicate the positive effect exerted by Rhizobium sp., in promoting growth and BNF, which could be used for further studies to establish the production of a biofertilizer, allowing potentiate the production of crops by gliricidia for food arich cattle as source of protein in the Caribbean Biotechnology Center.

  1. Identification and characterization of the Rhizobium sp. strain GIN611 glycoside oxidoreductase resulting in the deglycosylation of ginsenosides.

    Kim, Eun-Mi; Kim, Juhan; Seo, Joo-Hyun; Park, Jun-Seong; Kim, Duck-Hee; Kim, Byung-Gee

    2012-01-01

    Using enrichment culture, Rhizobium sp. strain GIN611 was isolated as having activity for deglycosylation of a ginsenoside, compound K (CK). The purified heterodimeric protein complex from Rhizobium sp. GIN611 consisted of two subunits with molecular masses of 63.5 kDa and 17.5 kDa. In the genome, the coding sequence for the small subunit was located right after the sequence for the large subunit, with one nucleotide overlapping. The large subunit showed CK oxidation activity, and the deglycosylation of compound K was performed via oxidation of ginsenoside glucose by glycoside oxidoreductase. Coexpression of the small subunit helped soluble expression of the large subunit in recombinant Escherichia coli. The purified large subunit also showed oxidation activity against other ginsenoside compounds, such as Rb1, Rb2, Rb3, Rc, F2, CK, Rh2, Re, F1, and the isoflavone daidzin, but at a much lower rate. When oxidized CK was extracted and incubated in phosphate buffer with or without enzyme, (S)-protopanaxadiol [PPD(S)] was detected in both cases, which suggests that deglycosylation of oxidized glucose is spontaneous. PMID:22020506

  2. Rhizobium leguminosarum is the symbiont of lentils in the Middle East and Europe but not in Bangladesh.

    Harun-or Rashid, M; Gonzalez, Javier; Young, J Peter W; Wink, Michael

    2014-01-01

    Lentil is the oldest of the crops that have been domesticated in the Fertile Crescent and spread to other regions during the Bronze Age, making it an ideal model to study the evolution of rhizobia associated with crop legumes. Housekeeping and nodulation genes of lentil-nodulating rhizobia from the region where lentil originated (Turkey and Syria) and regions to which lentil was introduced later (Germany and Bangladesh) were analyzed to determine their genetic diversity, population structure, and taxonomic position. There are four different lineages of rhizobia associated with lentil nodulation, of which three are new and endemic to Bangladesh, while Mediterranean and Central European lentil symbionts belong to the Rhizobium leguminosarum lineage. The endemic lentil grex pilosae may have played a significant role in the origin of these new lineages in Bangladesh. The presence of R. leguminosarum with lentil at the center of origin and in countries where lentil was introduced later suggests that R. leguminosarum is the original symbiont of lentil. Lentil seeds may have played a significant role in the initial dispersal of this Rhizobium species within the Middle East and on to other countries. Nodulation gene sequences revealed a high similarity to those of symbiovar viciae. PMID:24033582

  3. Homology of genes for exopolysaccharide synthesis in Rhizobium leguminosarum and effect of cloned exo genes on nodule formation

    Skorupska, A.; Derylo, M. [Uniwersytet Marii Curie-Sklodowskiej, Lublin (Poland)

    1993-12-31

    A 5.4 kb BamHI fragment of Rhizobium leguminosarum (R.l.) bv. trifolii TA1 was found to carry genes involved in exopolysaccharide synthesis (exo genes). This fragment was strongly hybridized to the total DNA from DNA from R.l. bv. viciae and bv. phaseoli digested with EcoRI. No homology was found with total DNA of R. melilotic and Rhizobium sp. NGR 234. The exo genes R.l. bv. trifolii TA1 conjugally introduced into R.l. bv. viciae 1302 considerably affected the symbiosis: the nodules induced on vetch were abortive and did not fix nitrogen. On the other hand, Phaseolus beans infected with R.l. bv. trifolii exo genes formed the nitrogen-fixing nodules. It can be conduced that additional copies of exo genes introduced into wild type R.l. strains can disturb the synthesis of acidic exopolysaccharides and affect symbiosis of the plants forming indeterminate nodules, but do not affect symbiosis of the plants forming the determinate nodules. (author). 29 refs, 2 figs, 2 tabs.

  4. Evaluation of microbial populations, Rhizobium Trifolii, and endomycorrhizal associations in reclamation of surface mine spoils in Texas

    Mott, J.B.

    1984-01-01

    The deficiency of nitrogen and phosphorus in mixed overburden mine spoils has resulted in interest in strategies to minimize fertilizer application. In this study, the abundance of microbial populations, with emphasis on those involved in nitrogen cycle transformations was estimated in variously aged spoils. Two beneficial plant-microbe associations, the clover-Rhizobium trifolii symbiosis and endomycorrhizal associations, were investigated in field and laboratory studies. While most groups of microorganisms regained pre-mining levels in revegetated spoils within 1.5 years after disturbance, algal populations were still reduced ten years after mining. Populations of nitrifying bacteria and asymbiotic nitrogen-fixing bacteria were as high in all spoils as in unmined soil. Indigenous populations of ineffective R. trifolii were present in spoil banks and older revegetated spoil. A laboratory study of survival of three commercial strains of R. trifolii for subterranean clover showed lethal effects of high temperature (45/sup 0/C) especially in moist spoil, and superior survival of strain 162X95. Endomycorrhizal associations, evaluated by assessment of root infection in bermudagrass, reached pre-mining levels by three to seven years after disturbance. Growth chamber studies to investigate the effects of the two symbiotic associations on subterranean clover in mine spoil at different fertility levels indicated that dual infection with Rhizobium and VAM fungi was most beneficial for plant growth, nitrogen fixation, and nitrogen and phosphorus contents.

  5. Glycine-Glomus-Rhizobium Symbiosis : VI. Photosynthesis in Nodulated, Mycorrhizal, or N- and P-Fertilized Soybean Plants.

    Brown, M S; Bethlenfalvay, G J

    1987-09-01

    Soybean (Glycine max [L.] Merr. cv Hobbit) plants were grown in a growth chamber for 56 days in a phosphorus- and nitrogen-deficient soil and were colonized by the vesicular-arbuscular mycorrhizal (VAM) fungus Glomus mosseae (Nicol. & Gerd) Gerd. and Trappe and Rhizobium japonicum strain USDA 136, or by either organism alone, or by neither. Non-VAM plants received supplemental phosphorus and nonnodulated plants supplemental nitrogen to achieve the same rate of growth in all treatments. Plants of all four treatments had the same (P > 0.05) dry weights at harvest, but VAM plants had higher rates of CO(2) exchange (CER, P phosphorus content) were associated with phosphorus nutrition (or the presence of the VAM fungus), others (leaf fresh weight and root dry weight) with nitrogen nutrition (or the presence of Rhizobium), and some (leaf nitrogen and starch content) by both factors. The development of microsymbiont structures and nodule activity were significantly lower in the tripartite association than in plants colonized by one endophyte only. The findings suggest that endophyte effects go beyond those of simple nutrition and associated source-sink relationships. PMID:16665642

  6. Homology of genes for exopolysaccharide synthesis in Rhizobium leguminosarum and effect of cloned exo genes on nodule formation

    A 5.4 kb BamHI fragment of Rhizobium leguminosarum (R.l.) bv. trifolii TA1 was found to carry genes involved in exopolysaccharide synthesis (exo genes). This fragment was strongly hybridized to the total DNA from DNA from R.l. bv. viciae and bv. phaseoli digested with EcoRI. No homology was found with total DNA of R. melilotic and Rhizobium sp. NGR 234. The exo genes R.l. bv. trifolii TA1 conjugally introduced into R.l. bv. viciae 1302 considerably affected the symbiosis: the nodules induced on vetch were abortive and did not fix nitrogen. On the other hand, Phaseolus beans infected with R.l. bv. trifolii exo genes formed the nitrogen-fixing nodules. It can be conduced that additional copies of exo genes introduced into wild type R.l. strains can disturb the synthesis of acidic exopolysaccharides and affect symbiosis of the plants forming indeterminate nodules, but do not affect symbiosis of the plants forming the determinate nodules. (author). 29 refs, 2 figs, 2 tabs

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

    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 (15NH4)2SO4 with 5%15N 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 15N isotope showed that the highest portion and value of N2-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)

  8. Ensifer, Phyllobacterium and Rhizobium species occupy nodules of Medicago sativa (alfalfa) and Melilotus alba (sweet clover) grown at a Canadian site without a history of cultivation

    Phage resistant and susceptible bacteria from nodules of alfalfa and sweet clover grown at a site without a known history of cultivation, were identified as Ensifer, Rhizobium and Phyllobacterium species based on sequence analysis of ribosomal (16S and 23S rRNA)and protein encoding (atpD and recA) g...

  9. Diglyceride Kinase Activity in Cell Extracts of Rhizobium meliloti: Evidence for a Diglyceride Cycle during Cyclic β-1,2-Glucan Biosynthesis

    Hunt, William P.; Gore, Richard S.; Miller, Karen J.

    1991-01-01

    In this article, we provide evidence for the presence of diglyceride kinase activity in cell extracts of Rhizobium meliloti 1021. Characterization of the rhizobial enzyme revealed that it shares many properties with the diglyceride kinase of Escherichia coli. A possible role for this enzyme during cyclic β-1,2-glucan biosynthesis is discussed.

  10. Heat Curing of a Sym Plasmid in a Fast-Growing Rhizobium sp. That Is Able To Nodulate Legumes and the Nonlegume Parasponia sp

    1983-01-01

    Genes involved in nodulation of both legumes and the nonlegume Parasponia sp., as well as nitrogenase genes, reside on a large plasmid in a fast-growing Rhizobium sp. from Lablab purpureus. This plasmid can be cured by incubation at elevated temperatures and can be mobilized by the P1 group plasmid RP1::Tn501.

  11. The structure and molecular mechanics calculations of the cyclic (1 → 2)-β- D-glucan secreted by Rhizobium tropici CIAT 899

    Gil Serrano, Antonio M.; Franco-Rodríguez, Guillermo; González-Jiménez, Isabel; Tejero-Mateo, Pilar; Molina, José Molina; Dobado, J. A.; Megías, Manuel; Romero, Maria Jesús

    1993-12-01

    The structure of the extracellular cyclic (1 → 2)-β- D-glucan secreted by Rhizobium tropici CIAT 899 has been studied by methylation analysis, 1D and 2D NMR experiments, HPLC and FAB-MS. Molecular mechanics (MM2) and theoretical 3JHH coupling constants calculations were performed.

  12. Intensity of Ground Cover Crop Arachis pintoi, Rhizobium Inoculation and Phosphorus Application and Their Effects on Field Growth and Nutrient Status of Cocoa Plants

    John Bako Baon

    2006-08-01

    Full Text Available Arachis pintoiis potentially as a cover crop for cocoa (Theobroma cacaoL. farm, however information regarding its effect on the growth of cocoa plants in the field is very limited. The objective of this experiment is to investigate the combined influence of ground cover crop A. pintoi, rhizobial bacterial inoculation and phosphorus (P fertilizer on the growth of cocoa in the field and nutrient status. This experiment laid out in split-split plot design consisted of three levels of cover crop (without, A. pintoiand Calopogonium caeruleum, two levels of rhizobium inoculation (not inoculated and inoculated and two levels of phosphorus application (no P added and P added. The results showed that in field condition the presence of A. pintoias cover crop did not affect the growth of cocoa. On the other hand, C. caeruleumas cover crop tended to restrict cocoa growth compared to A. pintoi. Application of P increased leaf number of cocoa plant. Biomass production of A. pintoiwas 40% higher than C. caeruleum. Soil organic carbon and nitrogen contents were not affected by ground cover crops, though higher value (0.235% N and 1.63% organic C was obtained from combined treatments of inoculation and P addition or neither inoculation nor P addition. In the case of no rhizobium inoculation, soil N content in cocoa farm with A. pintoicover crop was lower than that of without cover crop or with C. caeruleum. Cover crop increased plant N content when there was no inoculation, on the other hand rhizobium inoculation decreased N content of cocoa tissue. Tissue P content of cocoa plant was not influenced by A. Pintoicover crop or by rhizobium inoculation, except that the P tissue content of cocoa was 28% higher when the cover crop was C. caeruleumand inoculated. Key words : Arachis pintoi, Theobroma cacao, Calopogonium caeruleum, rhizobium, nitrogen, phosphorus.

  13. Is 'Final' Really Final?

    Tai, B

    2002-01-01

    Recently, the Appeal Committee of the Hong Kong Court of Final Appeal raised the question of whether that court had the power to hear an appeal against a decision of the Court of Appeal. The decision in question concerned a judgment of professional misconduct against an accountant by a disciplinary committee under the Professional Accountants Ordinance. The ordinance clearly states that the decision of the Court of Appeal is final. This article examines whether the Court of Final Appeal has t...

  14. Respuesta de combinaciones Rhizobium - Clitoria ternatea en condiciones de estrés salino en el Valle del Cauto en Cuba / Response of Rhizobium - Clitoria ternatea combinations under salt stress in the Cauto Valley in Cuba

    Raúl Carlos, López Sánchez; Roeland, Samson; Patrick, Vandamme; Bettina, Eichler-Löbermann; Ernesto, Gómez Padilla.

    2011-06-01

    Full Text Available Se estudió la respuesta de Clitoria ternatea en condiciones de estrés salino a la inoculación con aislamientos nativos y cepas comerciales de rizobios. El estudio se realizó en condiciones de invernadero y de campo. El efecto de tres cepas de rizobio (Jd19, 1031 y 1032) en el rendimiento y parámetro [...] s de la fijación de nitrógeno se comparó con el testigo y el tratamiento con fertilización nitrogenada. En el experimento en invernadero los mejores resultados para el rendimiento y parámetros de fijación de nitrógeno se encuentran con el aislamiento nativo de rizobio Jd19. En este tratamiento se encontraron los valores más altos de peso seco de masa aérea y raíces y de acumulación de nitrógeno. Además en el tratamiento con el aislamiento Jd19 se mostraron los valores más altos de relación K:Na, contenido de ureidos, clorofila a y b en el tallo y el mejor índice de efectividad de la inoculación. En el experimento de campo el tratamiento con el aislamiento Jd19 tuvo el mejor efecto positivo en comparación con el resto de los tratamientos. Los resultados indican que la combinación Clitoria ternatea-Jd19 es más eficiente en condiciones de estrés salino, y es posible su introducción a amplia escala en suelos afectados por la salinidad. Abstract in english The purpose of the present study was to examine response of Clitoria tarnatea under salt stress to inoculation with native isolates and commercial strains of Rhizobium. This study was carried out both in greenhouse and field conditions. Effects of three Rhizobium strains (Jd19, 1031 and 1032) were c [...] ompared to control and mineral N fertilization regarding yield and nitrogen fixation parameters. In the greenhouse experiment the best results for yield and nitrogen fixation parameters were found for the Jd19 native isolate treatment, where the highest dry weight of both shoots and roots and also of nitrogen uptake were observed. Besides, this treatment showed the highest K:Na ratio, as well as of contents of ureides, of a and b chlorophyll in stem and the best inoculation effectiveness index. In the field test, the Jd19 treatment showed the best positive effect in comparison to the other treatments. Results indicate that the Clitoria ternatea-Jd19 Rhizobium strain combination is the most efficient under salt stress and also that its wide scale introduction in saline soils is possible.

  15. Agrice et les tensioactifs

    Rocher Magali

    2001-01-01

    Agrice, Agriculture pour la chimie et l’énergie, est un groupement d’intérêt scientifique qui a pour objet l’animation, le financement, le suivi et l’évaluation de programmes de recherche et développement portant sur les nouvelles valorisations des produits et coproduits d’origine agricole dans les domaines de l’énergie, de la chimie et des matériaux. Aujourd’hui les programmes de recherche et développement sur les tensioactifs sont renforcés, plus sélectifs et plus directement tournés vers l...

  16. Molecular and culture dependent characterization of endolithic bacteria in two beach sand samples and description of Rhizobium endolithicum sp. nov.

    Parag, B; Sasikala, Ch; Ramana, Ch V

    2013-12-01

    Endolithic metagenome analysis of two beach samples collected form Chilika, Odisha, India indicated rich bacterial diversity. While the metagenome analysis of sample one yielded 16S rRNA gene sequences which represent six phyla and 16 genera, sample two yielded very rich diversity representing 17 phyla and 286 genera. Six species of bacteria were isolated from the endolithic enrichments and most of them have 16S rRNA gene sequence similarity of >99 % with known taxa, except for strain JC140(T) having Rhizobium yanglingense SH22623(T) (96.8 %), R. alkalisoli CCBAU 01393(T) (96.3 %), R. vignae CCBAU 05176(T) (96.2 %), R. mesosinicum CCBAU 25010(T) (96.1 %) and other members of the genus Rhizobium with characterized based on polyphasic taxonomic analysis. Strain JC140(T) could tolerate up to 5 % salinity, resistant to rifampicin (10 ?g) and was positive for catalase and oxidase. The major fatty acid is summed feature 8 (C18:1?7c/C18:1?6c) with minor amounts of C19:0 cyclo?8c, C16:0, C18:0, C17:0cyclo, summed feature 2 (C14:03OH/C16:1 isoI), summed feature 3 (C16:1?7c/C16:1?6c) and 2-hydroxyacid of C15:0. Diphosphatidylglycerol, phosphatidylethanol-amine, phosphatidylcholine, phosphatidylglycerol, unidentified lipids (L1, 2), unidentified phospholipid (PL1-4) constitute the polar lipids of strain JC140(T). The strain has bacteriohopane derivative (BHD2), diplopterol and two unidentified hopanes (UH1, 2) as major hopanoids. Q-10 is the major quinone of strain JC140(T). Based on polyphasic taxonomic analysis, strain JC140(T) represents a species in the genus Rhizobium for which, the name R. endolithicum sp. nov. is proposed. The type strain is JC140(T) (= KCTC32077(T) = CCUG64352(T) = MTCC11723(T) = HAMBI 2447(T)). PMID:24104485

  17. Inoculação do feijoeiro com Rhizobium tropici associada à exsudato de Mimosa flocculosa com diferentes doses de nitrogênio Rhizobium tropici associated with Mimosa flocculosa exudates inoculation effect on bean plants under different nitrogen rates

    Eulene Francisco da Silva

    2009-01-01

    Full Text Available O presente estudo teve como objetivo avaliar os efeitos da inoculação de rizóbio, associada à adição de exsudatos de sementes de Mimosa flocculosa, e/ou de N-mineral nas características agronômicas do feijoeiro, em sucessão à soja e ao milho. O delineamento experimental foi em blocos casualizados, com quatro repetições, sendo os tratamentos dispostos em parcelas sub-subdivididas. As culturas soja e milho antecessoras à cultura do feijoeiro formaram as parcelas. As subparcelas foram constituídas pelos tratamentos: testemunha sem inoculação, inoculação de Rhyzobium tropici, estirpes CIAT 899 e PRF 81 e a associação deste com os exsudados das sementes de Mimosa flocculosa. As sub-subparcelas constituiram-se de quatro doses de N aplicadas em cobertura: 0, 40, 80 e 120 kg ha-1. A inoculação de rizóbio associada à adição de exsudato de sementes de Mimosa flocculosa contribuiu para o melhor desenvolvimento da parte aérea do feijoeiro. A adubação nitrogenada reduziu, de forma linear, a nodulação do feijoeiro. O milho como cultura antecessora ao feijão contribuiu para o aumento do peso de 100 grãos e a adição de N combinado não contribuiu para o aumento do número de vagens por planta e produtividade de grãos do feijoeiro, independente da dose utilizada.The aim of this work was to evaluate the effect of the Rhizobium inoculation, associated with seed exudates of Mimosa flocculosa, under different rates of nitrogen fertilization was evaluated in bean crops following soybean (Glycine max L. Merril and corn (Zea mays L.. The experimental design was randomized blocks with four replications, with treatments arranged in sub-divided parcels. The parcels were constituted of two summer crops preceding the common bean crop: soybean and corn. In the sub-parcels three treatments involving inoculation of the common bean seeds were considered: control treatment without inoculation; bean seeds inoculated with Rhizobium tropici, strains CIAT 899 and PRF 81, and the association of Rhizobium with the exudates of the Mimosa flocculosa seeds. The sub-subparcels received of four doses of nitrogen fertilization applied on covering: 0, 40, 80 and 120 kg ha-1 N. The inoculation of Rhizobium associated with the addition of exudates of Mimosa flocculosa seeds resulted in higher shoot dry weight. Besides that, the nitrogen fertilization, on the tested doses, reduced, in a linear way, the nodulation of the bean plant. It was also verified that corn as a preceding crop for bean has contributed to the increase of the weight of 100 grains, while the addition of combined N did not contribute to the improvement on the number of beans per plant, neither of the grain yield of bean plants, independent of the dose that was used.

  18. A Rhizobium radiobacter Histidine Kinase Can Employ Both Boolean AND and OR Logic Gates to Initiate Pathogenesis.

    Fang, Fang; Lin, Yi-Han; Pierce, B Daniel; Lynn, David G

    2015-10-12

    The molecular logic gates that regulate gene circuits are necessarily intricate and highly regulated, particularly in the critical commitments necessary for pathogenesis. We now report simple AND and OR logic gates to be accessible within a single protein receptor. Pathogenesis by the bacterium Rhizobium radiobacter is mediated by a single histidine kinase, VirA, which processes multiple small molecule host signals (phenol and sugar). Mutagenesis analyses converged on a single signal integration node, and finer functional analyses revealed that a single residue could switch VirA from a functional AND logic gate to an OR gate where each of two signals activate independently. Host range preferences among natural strains of R. radiobacter correlate with these gate logic strategies. Although the precise mechanism for the signal integration node requires further analyses, long-range signal transmission through this histidine kinase can now be exploited for synthetic signaling circuits. PMID:26310519

  19. Endogenous indoles and the biosynthesis and metabolism of indole-3-acetic acid in cultures of Rhizobium phaseoli.

    Ernstsen, A; Sandberg, G; Crozier, A; Wheeler, C T

    1987-07-01

    Gas chromatography-mass spectrometric analyses of purified extracts from cultures of Rhizobium phaseoli wild-type strain 8002, grown in a non-tryptophan-supplemented liquid medium, demonstrated the presence of indole-3-acetic acid (IAA), indole-3-ethanol (IEt), indole-3-aldehyde and indole-3-methanol (IM). In metabolism studies with (3)H-, (14)C- and (2)H-labelled substrates the bacterium was shown to convert tryptophan to IEt, IAA and IM; IEt to IAA and IM; and IAA to IM. Indole-3-acetamide (IAAm) could not be detected as either an endogenous constituent or a metabolite of [(3)H]tryptophan nor did cultures convert [(14)C]IAAm to IAA. Biosynthesis of IAA in R. phaseoli, thus, involves a different pathway from that operating in Pseudomonas savastanio and Agrobacterium tumefaciens-induced crown-gall tumours. PMID:24227443

  20. Effect of Rhizobium and arbuscular mycorrhizal fungi inoculation on electrolyte leakage in Phaseolus vulgaris roots overexpressing RbohB.

    Arthikala, Manoj-Kumar; Nava, Noreide; Quinto, Carmen

    2015-01-01

    Respiratory oxidative burst homolog (RBOH)-mediated reactive oxygen species (ROS) regulate a wide range of biological functions in plants. They play a critical role in the symbiosis between legumes and nitrogen-fixing bacteria or arbuscular mycorrhizal (AM) fungi. For instance, overexpression of PvRbohB enhances nodule numbers, but reduces mycorrhizal colonization in Phaseolus vulgaris hairy roots and downregulation has the opposite effect. In the present study, we assessed the effect of both rhizobia and AM fungi on electrolyte leakage in transgenic P. vulgaris roots overexpressing (OE) PvRbohB. We demonstrate that elevated levels of electrolyte leakage in uninoculated PvRbohB-OE transgenic roots were alleviated by either Rhizobium or AM fungi symbiosis, with the latter interaction having the greater effect. These results suggest that symbiont colonization reduces ROS elevated electrolyte leakage in P. vulgaris root cells. PMID:25946118

  1. Mechanisms of protection of pea plants by polysaccharides extracted from a strain of Rhizobium against Orobanche crenata

    The Broomrape causes notable damage on the leguminous crops and became major factor limiting production of pea in the Mediterranean region. The effect of the polysaccharides extracted from P.SOM Rhizobium strain on the development of Orobanche crenata on pea was studied. The results showed that the lipopolysaccharides significantly reduce the infestation of pea by O. crenata. This limitation of infestation results from the reduction of seeds germination rates of the parasite resulting in reduction of the tubercles number on pea roots. Moreover, necrosis of orobanche before or after attachment on pea roots treated by LPS can explain this reduction of parasitism. A correlation was observed between the reduction of pea infection by the broomrape and the activation phenolic compounds pathway. This activation resulted to increase of two enzymes (peroxidase and polyphenoloxidase) activities these enzymes are implicated in plant defense. The results of our study showed that the LPS seem implied in the induction of pea resistance against the broomrape.

  2. In vitro Survival and Nematicidal Activity of Rhizobium, Bradyrhizobium and Sinorhizobium. I. The Influence of Various NaCl Concentrations

    S. Shahid Shaukat

    2002-01-01

    Full Text Available During the survey of the cultivated fields in Karachi and neighborhood (Southern Sindh, 3 strains of Rhizobium phaseoli, 1 strain of R. leguminosarum and R. trifolii each, 5 strains of Sinorhizobium meliloti, 2 strains of Bradyrhizobium japonicum and 3 strains of Bradyrhizobium sp. were isolated and identified. The 15 strains of rhizobia tested for their growth under saline media exhibited varying degree of effects to salt concentrations. Most resistant strain was that of S. meliloti MAT1(R9 while least resistant was that of Bradyrhizobium sp. VRM1(R13. All the rhizobial strains caused significant mortality of Meloidogyne incognita, the root-knot nematode juveniles in vitro, though the strains differed markedly in their toxic activity. The rhizobial strains showed significant interaction with NaCl salinity towards M. incognita

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

    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.

  4. Response of lupine plants irrigated with saline water to rhizobium inoculation using 15N-isotope dilution

    The lupine Rhizobium symbiosis and contribution of N2 fixation under different levels of irrigation water salinity were examined. Lysimeter experiment was established under greenhouse conditions during the year 2002-2003. In this experiment, inoculated plants were imposed to different salinity levels of irrigation water and N-fertilizer treatment. Plant height was decreased under different salinity levels, nitrogen treatments and bacterial inoculation. Similar trend was noticed with leaf area. The highest leaf area was recorded with salt tolerant bacterial inoculation (SBI) and splitting N-treatment. Highest values of N-uptake occurred after 100 day intervals under the tested factors. Relative decrease in N-uptake did not exceed 40% of those recorded with the fresh water treatment as affected by experimental factors. Nitrogen uptake by the whole plant reflected an increase at 3 dS/m salinity level of irrigation water. Relative increases were 5% and 15% for normal bacteria inoculation under single dose (NI) and splitting

  5. Crystallization and preliminary X-ray diffraction studies of maleylacetate reductase from Rhizobium sp. strain MTP-10005

    Fujii, Tomomi; Goda, Yuko [Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011 (Japan); Yoshida, Masahiro; Oikawa, Tadao [Department of Life Science and Biotechnology, Faculty of Chemistry, Materials and Bioengineering, Kansai University, Suita, Osaka 564-8680 (Japan); Hata, Yasuo, E-mail: hata@scl.kyoto-u.ac.jp [Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011 (Japan)

    2008-08-01

    Maleylacetate reductase from Rhizobium sp. strain MTP-10005 has been crystallized using the sitting-drop vapour-diffusion method and microseeding. The crystals contained one dimeric molecule per asymmetric unit and diffracted to 1.79 Å resolution. Maleylacetate reductase (EC 1.3.1.32), which catalyzes the reduction of maleylacetate to 3-oxoadipate, plays an important role in the aerobic microbial catabolism of resorcinol. The enzyme has been crystallized at 293 K by the sitting-drop vapour-diffusion method supplemented with a microseeding technique, using ammonium sulfate as the precipitating agent. The crystal belonged to the monoclinic space group C2, with unit-cell parameters a = 56.85, b = 121.13, c = 94.09 Å, β = 101.48°, and contained one dimeric molecule in the asymmetric unit. It diffracted to 1.79 Å resolution.

  6. Fluorescence studies with malate dehydrogenase from rhizobium japonicum 3I1B-143 bacteroids: a two-tryptophan containing protein

    Ghiron, Camillo A.; Eftink, Maurice R.; Waters, James K.; Emerich, David W.

    1990-05-01

    A number of fluorescence studies, both of trp residues and bound NADH, have been reported for porcine MDH. The large number of trp residues (6) complicates the interpretation of some studies. To circumvent this we have performed studies with a two tryptophan (per subunit) MDH from Rhizobium japonicum 311B-143 bacteroids. We have performed phase/modulation fluorescence lifetime measurements, as a function of temperature and added quencher KI, in order to resolved the 1.3 ns (blue) and 6.6 ns (red) contributions from the two classes of trp residues. Anisotropy decay studies have also been performed. The binding of NADH dynamically quenches the fluorescence of both tip residues, but, unlike mammalian cytoplasmic and mitochondrial MDH, there is not a large enhancement in fluorescence of bound NADH upon forming a ternary complex with either tartronic acid or D-malonate.

  7. Crystallization and preliminary X-ray diffraction studies of maleylacetate reductase from Rhizobium sp. strain MTP-10005

    Maleylacetate reductase from Rhizobium sp. strain MTP-10005 has been crystallized using the sitting-drop vapour-diffusion method and microseeding. The crystals contained one dimeric molecule per asymmetric unit and diffracted to 1.79 Å resolution. Maleylacetate reductase (EC 1.3.1.32), which catalyzes the reduction of maleylacetate to 3-oxoadipate, plays an important role in the aerobic microbial catabolism of resorcinol. The enzyme has been crystallized at 293 K by the sitting-drop vapour-diffusion method supplemented with a microseeding technique, using ammonium sulfate as the precipitating agent. The crystal belonged to the monoclinic space group C2, with unit-cell parameters a = 56.85, b = 121.13, c = 94.09 Å, β = 101.48°, and contained one dimeric molecule in the asymmetric unit. It diffracted to 1.79 Å resolution

  8. Comparison of the nitrogen-15 and conventional methods to determine N2 fixing capacity of chickpea by rhizobium strains

    The N2 fixing capacity of 8 strains of rhizobium ciceri (45, 68, 51,620, 29,18,23 and 31) in association with two cicer cultivars (Akcin-91 and Izmir-92) was evaluated under growth room conditions as a preliminary screening prior to field experimentation. The ''1''5N isotope method (A-value) was used to quantify the % Ndfa and actual amounts of N2 fixed. In addition to this, other conventional methods (dry matter, N content, total N uptake, difference method and symbiotic effectiveness) were also investigated in the comparison. The results obtained show that 18 and 31 number of strains could be successfully used as inoculant both cultivar

  9. AVALIAÇÃO DA FIXAÇÃO BIOLÓGICA DO NITROGÊNIO EM GENÓTIPOS DE FEIJOEIROS TOLERANTES A SECA EVALUATION OF BIOLOGICAL FIXATION OF NITROGEN IN RHIZOBIUM UNDER WATER DEFICIT

    Willian Bucker Moraes

    2010-04-01

    Full Text Available Vários fatores como a temperatura, acidez do solo, teor de nutrientes e cultivar, interferem na eficiência simbiótica das estirpes de Rhizobium em condições de campo. Com objetivo de avaliar a capacidade de fixação biológica de nitrogênio de estirpes nativas de Rhizobium sp. foi realizado um experimento em vasos montado no delineamento inteiramente casualizado no esquema fatorial 10x7 (10 linhagens de feijoeiro consideradas tolerantes ao déficit hídrico, sendo estas: Amarelinho, Macuquinho, Imperial, EL 22, BATT 477, Uirapuru, IAPAR-81, Bate Estrada, Serrano e Preto Meia Lua e 7 inoculantes isolados dos solos dos municipios de Colatina, Vila Pavão, Nova Venécia, Pinheiros, Sooretama, Linhares e Alegre, no estado do Espírito Santo, com quatro repetições. Os dados demonstraram que a fixação biológica de N2 utilizando a inoculação de estirpes eficientes de Rhizobium em cultivar nodulante de feijoeiro ou seu cultivo em solos com população nativa eficiente, pode possibilitar a suplementação ou até mesmo á não utilização de nitrogênio em cobertura na cultura do feijoeiro, sem perdas no rendimento da produtividade.Several factors as the temperature, soil acidity, content of nutrients and cultivate interfere in the symbiotic efficiency of the ancestries of Rhizobium infield conditions. With the objective of evaluating the capacity of biological fixation of nitrogen of native ancestries of Rhizobium sp. an experiment was accomplished in vases set up in the delineate entirely casualty in the factorial outline 10x7 (10 bean plant lineages considered tolerant to the water deficit, being these: Amarelinho, Macuquinho, Imperial, EL 22, BATT 477, Uirapuru, IAPAR-81, Bate Estrada, Serrano and Preto Meia Lua and 7 isolated inoculate of the soils of the municipal districts of Colatina, Vila Pavão, Nova Venécia, Pinheiros, Sooretama, Linhares and Alegre in Espírito Saint state, with four repetitions. The data demonstrated that the biological fixation of N2 using the inoculation of efficient ancestries of Rhizobium in cultivating bean plant nodule cultivation in soils with efficient native population, it can make possible the supplement or even to the not use of nitrogen in covering in the culture bean plant, without losses in the income of the productivity.

  10. Impact de la fabrication de charbon de bois sur la production et la disponibilité fourragère de pâturage en zone subaride, cas de la commune de Soalara-Sud, Toliara ll: Rapport final

    Raoliarivelo, L. I. B.; Rabeniala, R.; Masezamana, H. N.; Andrianarisoa, J. H.; Randriamalala, R. J.

    2010-01-01

    Ce projet a pour objectif de (1) décrire la filière charbon dans un terroir de la commune de Soalara, (2) d’identifier les effets des activités de fabrication de charbon de bois sur la végétation des pâturages qui est un fourré épineux et (3) d’estimer la quantité maximale de charbon pouvant être produite sans causer sa dégradation irréversible. Pour ce faire, des enquêtes auprès de la population locale et des relevés écologiques ont été entrepris. La majorité des ménages enquêtés (>80% ; N=5...

  11. ACTENA : Auscultation des cables tendus non accessibles : programme de recherche national supporté par l'Agence National de la Recherche et par Electricité de France : Rapport scientifique final

    Chazelas, Jean Louis; FORTIER, Stéphane; Abraham, Odile; BAYLASSAC, Jean Paul; BENMEDAKHENE, Salim; BOURSE, Gérard; FRACHELET, Franck; CHAIX, Jean François; COMELOUP, Gilles; Cottineau, Louis Marie; DEFER, Didier; Degauque, Pierre; Deschamps, Marc; GAILLET, Laurent; Garnier, Vincent

    2009-01-01

    Le programme de recherches ACTENA visait à ouvrir de nouvelles approches et à développer différentes méthodes d'auscultation non destructives des câbles tendus non accessibles dans le génie civil, essentiellement les câbles de précontrainte et les câbles d'ancrage des murs de soutènement. Le diagnostic de la pérennité de la précontrainte appelle deux réponses : la force de tension est-elle pérenne ? les ruptures passées ou en cours dans le câble réduisent-elle gravement les coefficients de sé...

  12. Nickel detoxification and plant growth promotion by multi metal resistant plant growth promoting Rhizobium species RL9.

    Wani, Parvaze Ahmad; Khan, Mohammad Saghir

    2013-07-01

    Pollution of the biosphere by heavy metals is a global threat that has accelerated dramatically since the beginning of industrial revolution. The aim of the study is to check the resistance of RL9 towards the metals and to observe the effect of Rhizobium species on growth, pigment content, protein and nickel uptake by lentil in the presence and absence of nickel. The multi metal tolerant and plant growth promoting Rhizobium strain RL9 was isolated from the nodules of lentil. The strain not only tolerated nickel but was also tolerant o cadmium, chromium, nickel, lead, zinc and copper. The strain tolerated nickel 500 ?g/mL, cadmium 300 ?g/mL, chromium 400 ?g/mL, lead 1,400 ?g/mL, zinc 1,000 ?g/mL and copper 300 ?g/mL, produced good amount of indole acetic acid and was also positive for siderophore, hydrogen cyanide and ammonia. The strain RL9 was further assessed with increasing concentrations of nickel when lentil was used as a test crop. The strain RL9 significantly increased growth, nodulation, chlorophyll, leghaemoglobin, nitrogen content, seed protein and seed yield compared to plants grown in the absence of bioinoculant but amended with nickel The strain RL9 decreased uptake of nickel in lentil compared to plants grown in the absence of bio-inoculant. Due to these intrinsic abilities strain RL9 could be utilized for growth promotion as well as for the remediation of nickel in nickel contaminated soil. PMID:23609454

  13. Thermophilic, reversible gamma-resorcylate decarboxylase from Rhizobium sp. strain MTP-10005: purification, molecular characterization, and expression.

    Yoshida, Masahiro; Fukuhara, Nobuhiro; Oikawa, Tadao

    2004-10-01

    We found the occurrence of thermophilic reversible gamma-resorcylate decarboxylase (gamma-RDC) in the cell extract of a bacterium isolated from natural water, Rhizobium sp. strain MTP-10005, and purified the enzyme to homogeneity. The molecular mass of the enzyme was determined to be about 151 kDa by gel filtration, and that of the subunit was 37.5 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis; in other words, the enzyme was a homotetramer. The enzyme was induced specifically by the addition of gamma-resorcylate to the medium. The enzyme required no coenzyme and did not act on 2,4-dihydroxybenzoate, 2,5-dihydroxybenzoate, 3,4-dihydroxybenzoate, 3,5-dihydroxybenzoate, 2-hydroxybenzoate, or 3-hydroxybenzoate. It was relatively thermostable to heat treatment, and its half-life at 50 degrees C was estimated to be 122 min; furthermore, it catalyzed the reverse carboxylation of resorcinol. The values of k(cat)/K(m) (mMu(-1) . s(-1)) for gamma-resorcylate and resorcinol at 30 degrees C and pH 7 were 13.4 and 0.098, respectively. The enzyme contains 327 amino acid residues, and sequence identities were found with those of hypothetical protein AGR C 4595p from Agrobacterium tumefaciens strain C58 (96% identity), 5-carboxyvanillate decarboxylase from Sphingomonas paucimobilis (32%), and 2-amino-3-carboxymuconate-6-semialdehyde decarboxylases from Bacillus cereus ATCC 10987 (26%), Rattus norvegicus (26%), and Homo sapiens (25%). The genes (graA [1,230 bp], graB [888 bp], and graC [1,056 bp]) that are homologous to those in the resorcinol pathway also exist upstream and downstream of the gamma-RDC gene. Judging from these results, the resorcinol pathway also exists in Rhizobium sp. strain MTP-10005, and gamma-RDC probably catalyzes a reaction just before the hydroxylase in it does. PMID:15466039

  14. Impact of dual inoculation with Rhizobium and PGPR on growth and antioxidant status of Vicia faba L. under copper stress.

    Fatnassi, Imen Challougui; Chiboub, Manel; Saadani, Omar; Jebara, Moez; Jebara, Salwa Harzalli

    2015-04-01

    Plant-growth-promoting bacteria (PGPR) may help reduce the toxicity of heavy metals in plants in polluted environments. In this work, the effects of dual inoculation with Rhizobium and PGPR strains on the growth of Vicia faba grown under copper stress were assessed during hydroponic culture. Growth parameters, copper (Cu) accumulation and antioxidant enzyme activities were studied. Copper concentrations above 1mM damaged plant growth, but co-inoculation reduced its harmful effect. Co-inoculation of plants treated with 1mM Cu and 2mM Cu increased the dry weights as compared with Cu-treated and uninoculated plants. However, it decreased copper uptake up to 80% in the roots of 1-mM-Cu-treated plants as compared to non-inoculated control. Copper tolerance in Vicia faba is linked to the activity of antioxidant systems that are modulated by metal concentrations: both superoxide dismutase (SOD) and catalase (CAT) were higher in the presence of Cu; a lower Cu dose of 0.5mM stimulated ascorbate peroxidase (APX) and/or peroxidase (POX) activities in shoots and roots; however in nodules CAT appeared to be the main peroxidase in H2O2 scavenging. The 1mM Cu treatment enhanced SOD, CAT and APX activities in roots and only SOD and POX were activated in shoots. All enzyme activities were inhibited by inoculation of 2mM Cu. The effect of inoculation with copper-accumulating PGPRs and the status of the antioxidant enzyme system were linked to changes in the copper tolerance status of Vicia faba. Our results suggested that Vicia faba inoculation with Rhizobium and PGPR Enterobacter clocae and Pseudomonas sp. could help to alleviate copper stress under hydroponic conditions. This result should be tested under field conditions for soil fertilization and phytostabilisation purposes. PMID:25747267

  15. NrcR, a New Transcriptional Regulator of Rhizobium tropici CIAT 899 Involved in the Legume Root-Nodule Symbiosis.

    Del Cerro, Pablo; Rolla-Santos, Amanda A P; Valderrama-Fernández, Rocío; Gil-Serrano, Antonio; Bellogín, Ramón A; Gomes, Douglas Fabiano; Pérez-Montaño, Francisco; Megías, Manuel; Hungría, Mariangela; Ollero, Francisco Javier

    2016-01-01

    The establishment of nitrogen-fixing rhizobium-legume symbioses requires a highly complex cascade of events. In this molecular dialogue the bacterial NodD transcriptional regulators in conjunction with plant inducers, mostly flavonoids, are responsible for the biosynthesis and secretion of Nod factors which are key molecules for successful nodulation. Other transcriptional regulators related to the symbiotic process have been identified in rhizobial genomes, including negative regulators such as NolR. Rhizobium tropici CIAT 899 is an important symbiont of common bean (Phaseolus vulgaris L.), and its genome encompasses intriguing features such as five copies of nodD genes, as well as other possible transcriptional regulators including the NolR protein. Here we describe and characterize a new regulatory gene located in the non-symbiotic plasmid pRtrCIAT899c, that shows homology (46% identity) with the nolR gene located in the chromosome of CIAT 899. The mutation of this gene, named nrcR (nolR-like plasmid c Regulator), enhanced motility and exopolysaccharide production in comparison to the wild-type strain. Interestingly, the number and decoration of Nod Factors produced by this mutant were higher than those detected in the wild-type strain, especially under salinity stress. The nrcR mutant showed delayed nodulation and reduced competitiveness with P. vulgaris, and reduction in nodule number and shoot dry weight in both P. vulgaris and Leucaena leucocephala. Moreover, the mutant exhibited reduced capacity to induce the nodC gene in comparison to the wild-type CIAT 899. The finding of a new nod-gene regulator located in a non-symbiotic plasmid may reveal the existence of even more complex mechanisms of regulation of nodulation genes in R. tropici CIAT 899 that may be applicable to other rhizobial species. PMID:27096734

  16. Une fosse du Bronze final IIb dans le Val d’Orléans à Sandillon (Loiret : données archéologiques et contexte environnemental A Late Bronze Age pit IIb in the Val d’Orléans at Sandillon (Loiret: archaeological data and environmental context

    Hélène Froquet

    2008-06-01

    Full Text Available Un diagnostic archéologique réalisé en 2004 à Sandillon (Loiret a permis la découverte d’une occupation du Bronze final IIb dans la plaine alluviale de la Loire. Les structures sont peu nombreuses, mais une fosse se distingue par un ensemble céramique exceptionnel par sa richesse, sa conservation et la présence de formes encore inconnues en région Centre. Ce corpus céramique, corrélé par une datation par radiocarbone, offre désormais un jalon fiable pour la région. Par ailleurs, ces vestiges ont pu être replacés dans leur environnement immédiat grâce à une étude géomorphologique et à l’analyse des restes carpologiques contenus dans la fosse. Ainsi, le croisement des données permet de tenter une approche paléo environnementale sur une occupation en contexte fluviatile et de préciser les relations entre l’homme et son milieu durant cette période chronologique.An archaeological diagnostic carried out in 2004 at Sandillon (Loiret enabled the discovery of a final Bronze Age IIb occupation in the alluvial Loire valley. There are few structures but one pit is noteworthy for a ceramic collection, exceptional in its abundance, its preservation and the presence of previously unknown forms in the Centre region. This ceramic corpus, dated by radiocarbon, henceforth provides a reliable standard for the region. Moreover, these relics could be set in their immediate environment thanks to a geomorphological study and to the analysis of carpological remains contained in the pit. So, the crossing of data allows us to attempt an environmental paleolithic approach to an occupation in a freshwater context and to clarify the relationship between man and his environment in this chronological period.

  17. Agrice et les tensioactifs

    Rocher Magali

    2001-03-01

    Full Text Available Agrice, Agriculture pour la chimie et l’énergie, est un groupement d’intérêt scientifique qui a pour objet l’animation, le financement, le suivi et l’évaluation de programmes de recherche et développement portant sur les nouvelles valorisations des produits et coproduits d’origine agricole dans les domaines de l’énergie, de la chimie et des matériaux. Aujourd’hui les programmes de recherche et développement sur les tensioactifs sont renforcés, plus sélectifs et plus directement tournés vers l’industrie et les marchés.

  18. Energie et développement

    Gilles Carbonnier

    2011-05-01

    Full Text Available Cet article introduit le dossier thématique consacré à la relation intime entre énergie et développement. Les auteurs retracent l’importance des énergies fossiles dans la croissance économique du monde occidental dès le XIXe siècle et le rôle central du pétrole au XXe siècle pour s’interroger sur les limites de ce modèle de développement face aux contraintes géologiques et climatiques. Ils examinent le fossé et les malentendus qui séparent les sciences de l’homme  et les sciences de la nature, ainsi que les récentes initiatives de dialogue interdisciplinaire autour de l’économie écologique et de l’écologie industrielle. Ils analysent ensuite les enjeux spécifiques aux pays en développement ainsi que l’inadéquation du système de gouvernance internationale pour faire face aux tensions croissantes liées à la déplétion du pétrole, aux asymétries d’accès et d’exploitation des ressources minérales et aux conséquences environnementales d’une consommation croissante de ressources non renouvelables.

  19. Etique et gerance

    Kliksberg, Bernardo

    2011-01-01

    L'auteur analyse le « vide éthique » dans lequel se trouvent plusieurs sociétés latinoaméricaines, la relation entre l'éthique et le leadership directif, et la conception des politiques économiques et sociales dans l'affectation des ressources des organisations.

  20. Et redskab i formskaben

    Thomsen, Bente Dahl

    Et innovativt didaktisk projekt, der arbejder med at udvikle et redskab til brug ved undervisningen i formskaben underlagt et universitært system. Det betyder at tidligere praksisbaseret læring i værksteder er omlagt til forskningsbaseret undervisning i auditoriumlignende lokaler. Projektet hvile...

  1. Final seminar of the 11A025 research project : Instrumentation and monitoring methods for civil engineering applications : Laboratoire Central des Ponts et Chaussées, Bouguenais, 14-15 décembre 2005

    LABORATOIRE CENTRAL DES PONTS ET CHAUSSEES - LCPC

    2005-01-01

    Le contrôle de structure ainsi que les outils associés s'y rattachant prennent de plus en plus une solide et croissante importantce pour les utilisateurs des méthodes expérimentales dans le génie civil. Les systèmes de mesure servent non seulement dans le cadre du suivi de la pathologie d'un pont ou d'un comportement défectueux, mais également en tant que vrais systèmes automatisés de prise de décision ou d'outils pour le contrôle actif de structure. De nos jours, ces systèmes comportent les ...

  2. ?-Galactoside Uptake in Rhizobium meliloti: Isolation and Characterization of agpA, a Gene Encoding a Periplasmic Binding Protein Required for Melibiose and Raffinose Utilization

    Gage, Daniel J.; Long, Sharon R.

    1998-01-01

    Rhizobium meliloti can occupy at least two distinct ecological niches; it is found in the soil as a free-living saprophyte, and it also lives as a nitrogen-fixing intracellular symbiont in root nodules of alfalfa and related legumes. One approach to understanding how R. meliloti alters its physiology in order to become an integral part of a developing nodule is to identify and characterize genes that are differentially expressed by bacteria living inside nodules. We used a screen to identify ...

  3. Potential for plant growth promotion in groundnut (Arachis hypogaea L.) cv. ALR-2 by co-inoculation of sulfur-oxidizing bacteria and Rhizobium.

    Anandham, R; Sridar, R; Nalayini, P; Poonguzhali, S; Madhaiyan, M; Sa, Tongmin

    2007-01-01

    The use of Rhizobium inoculant for groundnut is a common practice in India. Also, co-inoculation of Rhizobium with other plant growth-promoting bacteria received considerable attention in legume growth promotion. Hence, in the present study we investigated effects of co-inoculating the sulfur (S)-oxidizing bacterial strains with Rhizobium, a strain that had no S-oxidizing potential in groundnut. Chemolithotrophic S-oxidizing bacterial isolates from different sources by enrichment isolation technique included three autotrophic (LCH, SWA5 and SWA4) and one heterotrophic (SGA6) strains. All the four isolates decreased the pH of the growth medium through oxidation of elemental S to sulfuric acid. Characterization revealed that these isolates tentatively placed into the genus Thiobacillus. Clay-based pellet formulation (2.5 x 10(7) cf ug(-1) pellet) of the Thiobacillus strains were developed and their efficiency to promote plant growth was tested in groundnut under pot culture and field conditions with S-deficit soil. Experiments in pot culture yielded promising results on groundnut increasing the plant biomass, nodule number and dry weight, and pod yield. Co-inoculation of Thiobacillus sp. strain LCH (applied at 60 kg ha(-1)) with Rhizobium under field condition recorded significantly higher nodule number, nodule dry weight and plant biomass 136.9 plant(-1), 740.0mg plant(-1) and 15.0 g plant(-1), respectively, on 80 days after sowing and enhanced the pod yield by 18%. Also inoculation of S-oxidizing bacteria increased the soil available S from 7.4 to 8.43 kg ha(-1). These results suggest that inoculation of S-oxidizing bacteria along with rhizobia results in synergistic interactions promoting the yield and oil content of groundnut, in S-deficit soils. PMID:16574388

  4. High-quality permanent draft genome sequence of Rhizobium sullae strain WSM1592; a Hedysarum coronarium microsymbiont from Sassari, Italy

    Yates, Ron J.; Howieson, John G.; De Meyer, Sofie E.; Tian, Rui; Seshadri, Rekha; Pati, Amrita; Woyke, Tanja; Markowitz, Victor; Ivanova, Natalia; Kyrpides, Nikos; Loi, Angelo; Nutt, Bradley J.; Garau, Giovanni; Sulas, Leonardo; Wayne G. Reeve

    2015-01-01

    Rhizobium sullae strain WSM1592 is an aerobic, Gram-negative, non-spore-forming rod that was isolated from an effective nitrogen (N2) fixing root nodule formed on the short-lived perennial legume Hedysarum coronarium (also known as Sulla coronaria or Sulla). WSM1592 was isolated from a nodule recovered from H. coronarium roots located in Ottava, bordering Sassari, Sardinia in 1995. WSM1592 is highly effective at fixing nitrogen with H. coronarium, and is currently the commercial Sulla inocula...

  5. Alfalfa yield response to inoculation with recombinant strains of Rhizobium meliloti with an extra copy of dctABD and/or modified nifA expression.

    Bosworth, A H; M. K. Williams; Albrecht, K. A.; Kwiatkowski, R.; Beynon, J; Hankinson, T R; Ronson, C W; Cannon, F; Wacek, T. J.; Triplett, E W

    1994-01-01

    The construction of rhizobial strains which increase plant biomass under controlled conditions has been previously reported. However, there is no evidence that these newly constructed strains increase legume yield under agricultural conditions. This work tested the hypothesis that carefully manipulating expression of additional copies of nifA and dctABD in strains of Rhizobium meliloti would increase alfalfa yield in the field. The rationale for this hypothesis is based on the positive regula...

  6. Analysis of cellular fatty acids and phenotypic relationships of Agrobacterium, Bradyrhizobium, Mesorhizobium, Rhizobium and Sinorhizobium species using the Sherlock microbial identification system

    Tighe, S.W.; de Lajudie, Philippe; Dipietro, K.; Lindström, K.; Nick, G; Jarvis, B. D. W.

    2000-01-01

    Previous studies have demonstrated that cellular fatty acid analysis is a useful tool for identifying unknown strains of rhizobia and establishing taxonomic relationships between the species. In this study, the fatty acid profiles of over 600 strains belonging to the genera #Agrobacterium$, #Bradyrhizobium$, #Mesorhizobium$, #Rhizobium$ and #Sinorhizobium$ were evaluated using the gas-chromatography-based Sherlock Microbial Identification System (MIS). Data collected with the MIS showed that ...

  7. Flavone-enhanced accumulation and symbiosis-related biological activity of a diglycosyl diacylglycerol membrane glycolipid from Rhizobium leguminosarum biovar trifolii.

    Orgambide, G G; Philip-Hollingsworth, S; Hollingsworth, R I; Dazzo, F. B.

    1994-01-01

    Rhizobium leguminosarum bv. trifolii is the bacterial symbiont which induces nitrogen-fixing root nodules on the leguminous host, white clover (Trifolium repens L.). In this plant-microbe interaction, the host plant excretes a flavone, 4',7-dihydroxyflavone (DHF), which activates expression of modulation genes, enabling the bacterial symbiont to elicit various symbiosis-related morphological changes in its roots. We have investigated the accumulation of a diglycosyl diacylglycerol (BF-7) in w...

  8. The urease structural gene ureA in Rhizobium meliloti is preceded by an open reading frame necessary for urease activity.

    Miksch, G

    1994-12-01

    An open reading frame (ORF1) located upstream of the urease structural gene ureA in Rhizobium meliloti strain AK631 was cloned and characterized by DNA sequencing. Comparison of the amino acid sequence revealed partial homology with the urease accessory gene ureD of Klebsiella aerogenes and Proteus mirabilis. Mutational analysis of ORF1 showed that the gene is necessary for urease activity. Its function is still unknown. PMID:7813887

  9. Occurrence of enzymes involved in biosynthesis of indole-3-acetic acid from indole-3-acetonitrile in plant-associated bacteria, Agrobacterium and Rhizobium.

    Kobayashi, M.; Suzuki, T.; Fujita, T.; Masuda, M.; Shimizu, S.

    1995-01-01

    The occurrence of a hitherto unknown pathway involving the action of two enzymes, a nitrile hydratase and an amidase for the biosynthesis of indole-3-acetic acid was discovered in phytopathogenic bacteria Agrobacterium tumefaciens and in leguminous bacteria Rhizobium. The nitrile hydratase acting on indole-3-acetonitrile was purified to homogeneity through only two steps from the cell-free extract of A. tumefaciens. The molecular mass of the purified enzyme estimated by HPLC was about 102 kDa...

  10. COINOCULACIÓN DE Canavalia ensiformis (L. D.C. CON Rhizobium Y HONGOS MICORRÍZICOS ARBUSCULARES EN DOS TIPOS DE SUELOS DE CUBA

    Gloria M. Martín

    2015-01-01

    Full Text Available Para evaluar la respuesta de la canavalia (Canavalia ensiformis (L. D.C. a la coinoculación con cepas de Rhizobium y de hongos micorrízicos arbusculares (HMA, se condujo un experimento en condiciones de microparcelas que contenían suelo Ferralítico Rojo Lixiviado procedente del Departamento de Servicios Agrícolas del INCA, en San José de las Lajas, Mayabeque, y suelo Gley Nodular Ferruginoso procedente de la Estación de Pastos y Forrajes de Cascajal, Villa Clara. Se estudiaron cuatro cepas de Rhizobium (Can 2, Can 3, Can 4 y Can 5 y tres cepas de HMA: Glomus cubense (INCAM 4 y Rhizophagus intraradices (INCAM 11 para el suelo Ferralítico Rojo y Glomus cubense y Funneliformis mosseae (INCAM 2para el suelo Gley Nodular más los correspondientes testigos sin inoculación, para un total de 15 tratamientos por tipo de suelo, los cuales se distribuyeron en un diseño completamente aleatorizado con arreglo factorial (5 x 3 y tres repeticiones. Se evaluaron los indicadores del funcionamiento de la simbiosis micorrízica y el rendimiento de masa seca. Los resultados mostraron que la canavalia respondió positivamente a la coinoculación Rhizobium-HMA en ambos tipos de suelos. El mejor comportamiento de las cepas de Rhizobium se obtuvo con Can 3 para el suelo Ferralítico Rojo y Can 3, Can 4 y Can 5 para suelo Gley Nodular Ferruginoso, y las mejores cepas de HMA fueron, en ese orden, G. cubense y F. mosseae para uno y otro suelo, respectivamente.

  11. Host-dependent expression of Rhizobium leguminosarum bv. viciae hydrogenase is controlled at transcriptional and post-transcriptional levels in legume nodules.

    Brito Lopez, Maria Belen; Toffanin, Annita; Prieto Carbajo, Rosa Isabel; Imperial Ródenas, Juan; Ruiz Argüeso, Tomas-Andres; Palacios Alberti, Jose Manuel

    2008-01-01

    TThe legume host affects the expression of Rhizobium leguminosarum hydrogenase activity in root nodules. High levels of symbiotic hydrogenase activity were detected in R. leguminosarum bacteroids from different hosts, with the exception of lentil (Lens culinaris). Transcription analysis showed that the NifA-regulated R. leguminosarum hydrogenase structural gene promoter (P1) is poorly induced in lentil root nodules. Replacement of the P1 promoter by the FnrN-dependent promoter of the fixN gen...

  12. Genetic analysis and phenotypic characterization of three novel genes of Rhizobium tropici CIAT899 involved in symbiotic interactions with Phaseolus vulgaris

    Rojas Jimenez, Keilor

    2005-01-01

    Rhizobium tropici CIAT899 is highly tolerant to many environmental stresses and a good competitor for nodule occupancy of Phaseolus vulgaris. Random transposon mutagenesis was performed with the aim to identify novel genes of this strain involved in symbiosis and stress tolerance. The analysis of the locus disrupted by the Tn5 insertion in mutants 899-PV9 and 899-PV4 led the discovery of three novel genes required for and efficien...

  13. Sodium Dodecyl Sulfate-Polyacrylamide Gel Electrophoresis Protein Banding Patterns among Rhizobium leguminosarum biovar phaseoli Strains Isolated from the Mexican Bean Phaseolus coccineus

    Arredondo-peter, R.; Escamilla, E

    1993-01-01

    Several rhizobial strains were isolated from Phaseolus coccineus root nodules and were determined to be Rhizobium leguminosarum biovar phaseoli strains after reinfection of the same host plant. These strains were characterized by cultural procedures (growth on different carbon sources and intrinsic antibiotic resistance) and electrophoretic procedures (sodium dodecyl sulfate-polyacrylamide gel electrophoresis of total proteins). Our results showed that these rhizobia are very similar to each ...

  14. Effect of Rhizobium Inoculation and Supplementation with Phosphorus and Potassium on Growth and Total Leaf Chlorophyll (Chl) Content of Bush Bean Phaseolus vulgaris, L.

    Abdulkadir Mfilinge; Kelvin Mtei; Patrick Ndakidemi

    2014-01-01

    The study was conducted to investigate the effect of Rhizobium inoculation and supplementation of phosphorus and potassium on growth and total leaf chlorophyll content to the three released bush bean varieties in northern Tanzania. To achieve this aim, the glasshouse experiment was conducted at Nelson Mandela African Institution of Science and Technology while field experiment were carried out at Tanzania Coffee Research Institute, in Kilimanjaro, Tanzania between April-July...

  15. Sequence and analysis of the rpoN sigma factor gene of rhizobium sp. strain NGR234, a primary coregulator of symbiosis.

    van Slooten, J C; Cervantes, E; Broughton, W J; Wong, C H; Stanley, J

    1990-01-01

    We report the nucleotide sequence of the rpoN gene from broad-host-range Rhizobium sp. strain NGR234 and analyze the encoded RPON protein, a sigma factor. Comparative analysis of the deduced amino acid sequence of RPON from NGR234 with sequences from other gram-negative bacteria identified a perfectly conserved RPON box unique to RPON sigma factors. Symbiotic regulatory phenotypes were defined for a site-directed internal deletion within the coding sequence of the rpoN gene of Rhizobium strain NGR234: they included quantitative nodulation kinetics on Vigna unguiculata and microscopic analysis of the Fix- determinate nodules of V. unguiculata and Macroptilium atropurpureum. RPON was a primary coregulator of nodulation and was implicated in establishment or maintenance of the plant-synthesized peribacteroid membrane. Phenotypes of rpoN in Rhizobium strain NGR234 could be grouped as symbiosis related, rather than simply pleiotropically physiological as in free-living bacteria such as Klebsiella pneumoniae and Pseudomonas putida. Images PMID:2211497

  16. Study of vibrations and stabilization of linear collider final doublets at the sub-nanometer scale; Etude des vibrations et de la stabilisation a l'echelle sous-nanometrique des doublets finaux d'un collisionneur lineaire

    Bolzon, B

    2007-11-15

    CLIC is one of the current projects of high energy linear colliders. Vertical beam sizes of 0.7 nm at the time of the collision and fast ground motion of a few nanometers impose an active stabilization of the final doublets at a fifth of nanometer above 4 Hz. The majority of my work concerned vibrations and active stabilization study of cantilever and slim beams in order to be representative of the final doublets of CLIC. In a first part, measured performances of different types of vibration sensors associated to an appropriate instrumentation showed that accurate measurements of ground motion are possible from 0.1 Hz up to 2000 Hz on a quiet site. Also, electrochemical sensors answering a priori the specifications of CLIC can be incorporated in the active stabilization at a fifth of nanometer. In a second part, an experimental and numerical study of beam vibrations enabled to validate the efficiency of the numerical prediction incorporated then in the simulation of the active stabilization. Also, a study of the impact of ground motion and of acoustic noise on beam vibrations showed that an active stabilization is necessary at least up to 1000 Hz. In a third part, results on the active stabilization of a beam at its two first resonances are shown down to amplitudes of a tenth of nanometer above 4 Hz by using in parallel a commercial system performing passive and active stabilization of the clamping. The last part is related to a study of a support for the final doublets of a linear collider prototype in phase of finalization, the ATF2 prototype. This work showed that relative motion between this support and the ground is below imposed tolerances (6 nm above 0.1 Hz) with appropriate boundary conditions. (author)

  17. Monstres et murailles, Alexandre et bicornu, mythes et bon sens

    Jean-Louis Bacqué-Grammont

    2009-05-01

    Full Text Available Parmi les mythes récurrents à travers les lieux et les âges, celui du bâtisseur de murailles défendant une humanité civilisée contre l'Autre, sous ses aspects les plus effrayants, a connu une durable fortune depuis le prototype d'un Alexandre le Grand légendaire jusqu'à des avatars composites, bien vivaces dans nombre de littératures islamiques.En trois points différents de cet inépuisable domaine de recherche, chacun des auteurs a procédé à un sondage sommaire. Il en ressort maint exemple de continuités, de parallélismes et de confluences complexes, mais aussi les premiers signes d'érosion des mythes sous l'effet d'un esprit critique attisé par le vent d'Occident.

  18. Déserts et Thébaïdes (suite

    Loïc Windels

    2012-06-01

    Full Text Available Faisant suite aux trois volets de notre analyse des traductions allemandes de l’incipit de Bouvard et Pécuchet, cet article se détache de la traduction comme pratique herméneutique pour la regarder au miroir d’autres approches du texte flaubertien, et en confirmer la lecture en la complétant, notamment par une attention portée aux noms propres, cet angle mort de la pratique traductive. Nous continuerons donc à rapprocher Antoine de Bouvard et Pécuchet, mais en recherchant cette fois la trace désertique du saint dans les anthroponymes et la topographie du roman parisien. Mais l’onomastique de Bouvard est, comme le roman lui-même, placé sous le signe de la copie, et il nous faudra donc chemin faisant élargir l’intertexte à Madame Bovary et à L’Éducation sentimentale.

  19. Migrations et changements climatiques

    Piguet, Etienne; Pécoud, Antoine; de Guchteneire, Paul

    2010-01-01

    Cet article propose un tour d’horizon des débats relatifs aux possibles conséquences migratoires du changement climatique. Après un bref historique, nous examinons l'impact sur les migrations des trois principaux facteurs environnementaux liés aux changements climatiques (cyclones tropicaux, fortes pluies et inondations ; sécheresses et désertification ; élévation du niveau de la mer). Les questions fondamentales que soulève la relation entre changement climatique et migration sont ensuite ab...

  20. Supersymetrie et mathematiques

    Gieres, Francois

    1994-01-01

    Nous presentons une introduction aux concepts de la supersymetrie par l'intermediaire de trois exemples: (i) Mecanique quantique supersymetrique, (ii) Superalgebres de Lie, (iii) Superconnexions de Quillen. Les points communs a toutes ces notions sont soulignes et des applications sont indiquees. En particulier nous esquissons la demonstration du theoreme de Gauss et Bonnet d'apres Patodi et la demonstration des inegalites de Morse d'apres Witten.

  1. RHIZOBIUM ETLI USDA9032 ENGINEERED TO PRODUCE A PHENAZINE ANTIBIOTIC INHIBITS THE GROWTH OF FUNGAL PATHOGENS BUT IS IMPAIRED IN SYMBIOTIC PERFORMANCE

    Phenazine antibiotics produced by Pseudomonas spp. play a major role in preventing various plant diseases. In this study, the phenazine biosynthesis locus of P. chlororaphis O6, a plant growth-promoting rhizobacteria (PGPR), was introduced into several symbiotic bacteria belonging to the family Rh...

  2. Et dansk hotell

    Baca, Susan; Busck, Ole Gunni

    Rapporten præsenterer resultatet af en undersøgelse af, hvorledes et hotel i Nordjylland fungerer som arbejdsplads for indvandrere af overvejende ikke-vestlig oprindelse. Der fokuseres på i hvilket omfang og gennem hvilke mekanismer arbejdsmiljjøet i bred forstand, herunder forhold i ledelsen...

  3. Evidence Suggesting Protozoan Predation on Rhizobium Associated with Germinating Seeds and in the Rhizosphere of Beans (Phaseolus vulgaris L.).

    Ramirez, C; Alexander, M

    1980-09-01

    Changes in populations of microorganisms around germinating bean (Phaseolus vulgaris L.) seeds, in the rhizosphere of bean, and in a model rhizosphere were studied. Strains of Rhizobium phaseoli that were resistant to streptomycin and thiram were used, and as few as 300 R. phaseoli cells per g of soil could be enumerated with a selective medium that was devised. A direct role was not evident for bacterial competitors, lytic bacteria, antibiotic-producing microorganisms, bacteriophages, and Bdellovibrio in the suppression of R. phaseoli around germinating seeds and in the rhizosphere. Protozoa increased in numbers in the soil upon planting of the seeds. The extent of colonization of soil by R. phaseoli was inversely related to the presence of large numbers of bacteria and protozoa. Colonization of R. phaseoli was improved upon suppression of protozoa with thiram and also when the soil was amended with other protozoan inhibitors and mannitol to simulate seed and root exudation. The data support the view that the decrease in numbers of R. phaseoli is caused by an increase in protozoan predation, the protozoa increasing in number because they prey on bacteria that proliferate by using seed and root exudates as nutrients. PMID:16345628

  4. Biologic fixation of nitrogen in irradiated rhizobium strips; Fixacao biologica do nitrogenio em estirpes de rizobianas irradiadas

    Caribe, Rebeka Alves; Colaco, Waldeciro [Pernambuco Univ., Recife, PE (Brazil). Dept. de Energia Nuclear

    2002-07-01

    Native Rhizobium sp. and Bradyrhizobium sp. isolates from the root nodules of bean and cowpea were selected. Six isolates, and the SEMIA 4077 (R. leguminosarum bv. phaseolus) and SEMIA 6145 (Bradyrhizobium sp) strains used as references, were irradiated with ultraviolet light (R-uv) and gamma rays (R-{gamma}). The D{sub 37} values for the rhizobial strain SEMIA 4077 were 43 J.m{sup -2} (UV) and 32 Gy (R-{gamma}) and for the SEMIA 6145 were 45 J.m{sup -2} (UV) and 35 Gy (R-gamma). Through a greenhouse experiment the irradiated isolates were inoculated on bean (P. vulgaris L., cv. Princesa) and on cowpea [Vigna unguiculata, (L.) Walp, cv. IPA-206] seedlings, in an attempt to evaluate the sensitivity of the host plants, and possible effects on their nodulation. Differences in responses to nodulation due to the effect of irradiation were observed for the isolates tested. Significantly differences were observed only for nodules dry matter yield of the IPA-206 cultivar. Gamma irradiated treatment were statistically superior to treatments with ultraviolet light in relation. (author)

  5. Biotin production under limiting growth conditions by Agrobacterium/Rhizobium HK4 transformed with a modified Escherichia coli bio operon.

    Shaw; Lehner; Fuhrmann; Kulla; Brass; Birch; Tinschert; Venetz; Venetz; Sanchez; Tonella; Hochstrasser

    1999-06-01

    The E. coli biotin (bio) operon was modified to improve biotin production by host cells: (a) the divergently transcribed wild-type bio operon was re-organized into one transcriptional unit; (b) the wild-type bio promoter was replaced with a strong artificial (tac) promoter; (c) a potential stem loop structure between bioD and bioA was removed; and (d) the wild-type bioB ribosomal binding site (RBS) was replaced with an artificial RBS that resulted in improved bioB expression. The effects of the modifications on the bio operon were studied in E. coli by measuring biotin and dethiobiotin production, and bio gene expression with mini-cells and two-dimensional polyacrylamide gel electrophoresis. The modified E. coli bio operon was introduced into a broad host-range plasmid and used to transform Agrobacterium/Rhizobium HK4, which then produced 110 mg L-1 of biotin in a 2-L fermenter, growing on a defined medium with diaminononanoic acid as the starting material. Biotin production was not growth-phase dependent in this strain, and the rate of production remained high under limiting (maintenance) and zero growth conditions. PMID:10455485

  6. Genetic diversity of indigenous Rhizobium leguminosarum bv. viciae isolates nodulating two different host plants during soil restoration with alfalfa

    Zhang, X.X.; Kosier, B.; Priefer, U.B. [Rheinisch-Westfaelische TH Aachen, Aachen (Germany)

    2001-09-01

    A total of 360 Rhizobium leguminosarum bv. viciae strains was isolated from three brown-coal mining restoration fields of different age and plant cover (without and in the first and second year of alfalfa, Medicago sativa, cultivation) using two host species (Vicia hirsuta and Pisum sativum) as capture plants. The strains were genetically typed by restriction fragment length polymorphism analysis of polymerase chain reaction (PCR)-generated 16S-23S ribosomal DNA intergenic spacer regions (IGS-RFLP) and characterized by plasmid profiles and RFLP analysis of amplified nodABC genes. The R. leguminosarum bv. viciae population was dominated by the same group of strains (irrespective of the trap plant used). According to type richness, the genetic diversity of indigenous R. leguminosarum in the second year of restoration was lower than in the first year and it resembled that of the fallow field, except for plasmid types, in which it was higher than that of the fallow field. Some of the less frequent nodABC genotypes were associated with distinct chromosomal IGS genotypes and symbiotic plasmids (pSyms) of different sizes, indicating that horizontal transfer and rearrangements of pSym can occur in natural environments. However, the dominant pSym and chromosomal genotypes were strictly correlated suggesting a genetically stable persistence of the prevailing R. leguminosarum bv, viciae genotypes in the absence of its host plant.

  7. [Role of Bacterial Adhesin RAPA1 in Formation of Efficient Symbiosis of Rhizobium leguminosarum with Bean Plants].

    Nigmatullina, L R; Lavina, A M; Vershinina, Z R; Baimiev, Al Kh

    2015-01-01

    Bacterial adhesins, the proteins responsible for attachment of plant growth-promoting rhizobacteria to plant roots, are involved in formation of stable associative symbioses. In the present work enhanced expression of the rapA1 adhesin gene in Rhizobium leguminosarum PVu5 was shown to improve the efficiency of nodulation on bean roots inoculated with the modified strain. The rapA1 gene was cloned into the pJN105Turbo plasmid, this construct was used for transformation of R. leguminosarum PVu5, bean plants were inoculated by this transgenic strain, and efficiency of root nodule formation was determined. In the plants treated with rapA1-transgenic rhizobia, the number of root nodules was on average two times higher than in the plants inoculated with the original strain. Aggregation of R. leguminosarum was achieved when the rapA1 gene expression was enhanced either in rhizobia or in the co-cultured modified strain E. coli pJN105TurboRapA1. PMID:26964360

  8. Rhizobium leguminosarum COMO ORGANISMO BIOCONTROLADOR DE LA INTERACCIÓN HOSPEDERO-PATÓGENO: CLAVEL (Dianthus caryophyllus – Fusarium Oxysporum f. sp. dianthi

    Cheol Woo Lee Park

    2010-08-01

    Full Text Available Se investigó el efecto de biocontrol de Rhizobium leguminosarum (R. leguminosarum cepa B, contra Fusarium oxysporum f.sp.dianthi (FOD raza 2, en la interacción Clavel - FOD. Se utilizó la raza 2 de FOD por ser la de mayor patogenicidad y distribución en las fincas de cultivo de clavel en Colombia. Para ello se establecieron las condiciones de inoculación de FOD sobre cultivos establecidos de R . leguminosarum, variando la concentración in vitro de la bacteria. Se encontró una reducción en el número de microconidias hasta un 90% y una inhibición en el crecimiento radial del patógeno de hasta un 71 %. En el ensayo de microcultivo dual se detectó fraccionamiento de las hifas después de 48 horas de incubación con R . leguminosarum En el ensayo in vivo, los esquejes de clavel Raggio di solé, variedad susceptible al patógeno, fueron inoculados con 45.0 x 10 células de R. leguminosarum por matero, mostrando una severidad inferior al 5%, una incidencia menor del 20% y una reducción del índice de la enfermedad hasta de un 92% en presencia del patógeno.

  9. Enhanced Synthesis of Antioxidant Enzymes, Defense Proteins and Leghemoglobin in Rhizobium-Free Cowpea Roots after Challenging with Meloydogine incognita

    Jose T. A. Oliveira

    2014-11-01

    Full Text Available The root knot nematodes (RKN, Meloydogine spp., particularly Meloidogyne incognita and Meloidogyne javanica species, parasitize several plant species and are responsible for large annual yield losses all over the world. Only a few available chemical nematicides are still authorized for RKN control owing to environmental and health reasons. Thus, plant resistance is currently considered the method of choice for controlling RKN, and research performed on the molecular interactions between plants and nematodes to identify genes of interest is of paramount importance. The present work aimed to identify the differential accumulation of root proteins of a resistant cowpea genotype (CE-31 inoculated with M. incognita (Race 3 in comparison with mock-inoculated control, using 2D electrophoresis assay, mass spectrometry identification and gene expression analyses by RT-PCR. The results showed that at least 22 proteins were differentially represented in response to RKN challenge of cowpea roots mainly within 4–6 days after inoculation. Amongst the up-represented proteins were SOD, APX, PR-1, β-1,3-glucanase, chitinases, cysteine protease, secondary metabolism enzymes, key enzymes involved in ethylene biosynthesis, proteins involved in MAPK pathway signaling and, surprisingly, leghemoglobin in non-rhizobium-bacterized cowpea. These findings show that an important rearrangement in the resistant cowpea root proteome occurred following challenge with M. incognita.

  10. Symbiotic Efficiency of Native and Exotic Rhizobium Strains Nodulating Lentil (Lens culinaris Medik. in Soils of Southern Ethiopia

    Wondwosen Tena

    2016-02-01

    Full Text Available Lentil plays a major role in the food and nutritional security of low income Ethiopian families because of the high protein content of their seed; however, their productivity typically is low largely due to soil fertility limitations. Field and pot experiments were conducted during the 2011 cropping season to determine the effectiveness of Rhizobium strains on two cultivars of lentil in Southern Ethiopia. Six rhizobial inoculant treatments (four indigenous and two commercial inoculants, a nitrogen (N fertilizer treatment (50 kg·urea·ha−1 and an absolute control (non-inoculated non-fertilized were used. Inoculated plants produced significantly higher nodule number, nodule dry weight, grain yield and yield components than non-inoculated non-fertilized plants. Inoculation of field grown lentil with rhizobia strain Lt29 and Lt5 enhanced seed yield by 59% and 44%, respectively. Whereas urea fertilization enhanced yields by 40%. Similarly, grain yields were increased during the pot experiment by 92% and 67% over the control treatments by inoculation with Lt29 and Lt5, respectively. The highest levels of N fixation were achieved in plants inoculated with Lt29 (65.7% Ndfa. Both field and pot investigations indicate that inoculation of lentil with native rhizobial strains replace the need for inorganic N fertilization to optimize lentil yields.

  11. Predominant nifH transcript phylotypes related to Rhizobium rosettiformans in field-grown sugarcane plants and in Norway spruce.

    Burbano, Claudia Sofía; Liu, Yuan; Rösner, Kim Leonie; Reis, Veronica Massena; Caballero-Mellado, Jesus; Reinhold-Hurek, Barbara; Hurek, Thomas

    2011-06-01

    Although some sugarcane cultivars may benefit substantially from biological nitrogen fixation (BNF), the responsible bacteria have been not identified yet. Here, we examined the active diazotrophic bacterial community in sugarcane roots from Africa and America by reverse transcription (RT)-PCR using broad-range nifH-specific primers. Denaturing gradient gel electrophoresis (DGGE) profiles obtained from sugarcane showed a low diversity at all sample locations with one phylotype amounting up to 100% of the nifH transcripts. This major phylotype has 93.9-99.6% DNA identity to the partial nifH sequence from a strain affiliated with Rhizobium rosettiformans. In addition, nifH transcripts of this phylotype were also detected in spruce roots sampled in Germany, where they made up 91% of nifH transcripts detected. In contrast, in control soil or shoot samples two distinct nifH transcript sequences distantly related to nifH from Sulfurospirillum multivorans or Bradyrhizobium elkanii, respectively, were predominant. These results suggest that R. rosettiformans is involved in root-associated nitrogen fixation with sugarcane and spruce, plants that do not form root-nodule symbioses. PMID:23761284

  12. Direct amplification of nodD from community DNA reveals the genetic diversity of Rhizobium leguminosarum in soil.

    Zézé, A; Mutch, L A; Young, J P

    2001-06-01

    Sequences of nodD, a gene found only in rhizobia, were amplified from total community DNA isolated from a pasture soil. The polymerase chain reaction (PCR) primers used, Y5 and Y6, match nodD from Rhizobium leguminosarum biovar trifolii, R. leguminosarum biovar viciae and Sinorhizobium meliloti. The PCR product was cloned and yielded 68 clones that were identified by restriction pattern as derived from biovar trifolii [11 restriction fragment length polymorphism (RFLP) types] and 15 clones identified as viciae (seven RFLP types). These identifications were confirmed by sequencing. There were no clones related to S. meliloti nodD. For comparison, 122 strains were isolated from nodules of white clover (Trifolium repens) growing at the field site, and 134 from nodules on trap plants of T. repens inoculated with the soil. The nodule isolates were of four nodD RFLP types, with 77% being of a single type. All four of these patterns were also found among the clones from soil DNA, and the same type was the most abundant, although it made up only 34% of the trifolii-like clones. We conclude that clover selects specific genotypes from the available soil population, and that R. leguminosarum biovar trifolii was approximately five times more abundant than biovar viciae in this pasture soil, whereas S. meliloti was rare. PMID:11472501

  13. Effect of N-rate and P sources on BNF in soybean as affected by rhizobium and VAM fungi lnoculants

    Greenhouse experiment was made to investigate the influence of phosphate fertilizers on nitrogen fixation in soybean. The N-15 isotope dilution method was used to quantify N 2-fixed. In this concern, seed of nodulated and on-nodulated soybean plant bacterized with Bradyrhizobium japonicum and noculated without or with mycorrhizas in the presence of super or rock phosphate. Ammonium sulphate labelled fertilizer (5% N-15 a.e) was applied o 15 kg sandy soil of egypt at the rate of 20 and 100 kg N/acre. At re-flowering stage, the highest amount of N derived from air (Ndfa) was 66.3 and 470.2 (mg/pot) equivalent 47.6 and 47.1 of total N assimilated for noculated soybean with Rhizobium and fertilized with super or rock phosphate, respectively. While the contributions from 15 N labelled fertilizer (Ndff) accounted for 11 and 10.8, respectively. Use of mycorrhizas could increase the amount of N 2-fixed in the presence of rhizobia. There appears to be a strong case for improving N 2-fixation in the presence of mycorrhizas especially in sandy soil. 4 tabs

  14. Extended region of nodulation genes in Rhizobium meliloti 1021. II. Nucleotide sequence, transcription start sites and protein products

    The authors have established the DNA sequence and analyzed the transcription and translation products of a series of putative nodulation (nod) genes in Rhizobium meliloti strain 1021. Four loci have been designated nodF, nodE, nodG and nodH. The correlation of transposon insertion positions with phenotypes and open reading frames was confirmed by sequencing the insertion junctions of the transposons. The protein products of these nod genes were visualized by in vitro expression of cloned DNA segments in a R. meliloti transcription-translation system. In addition, the sequence for nodG was substantiated by creating translational fusions in all three reading frames at several points in the sequence; the resulting fusions were expressed in vitro in both E. coli and R. meliloti transcription-translation systems. A DNA segment bearing several open reading frames downstream of nodG corresponds to the putative nod gene mutated in strain nod-216. The transcription start sites of nodF and nodH were mapped by primer extension of RNA from cells induced with the plant flavone, luteolin. Initiation of transcription occurs approximately 25 bp downstream from the conserved sequence designated the nod box, suggesting that this conserved sequence acts as an upstream regulator of inducible nod gene expression. Its distance from the transcription start site is more suggestive of an activator binding site rather than an RNA polymerase binding site

  15. Complete genome sequence of Rhizobium leguminosarum bv. trifolii strain WSM1325, an effective microsymbiont of annual Mediterranean clovers.

    Reeve, Wayne [Murdoch University, Perth, Australia; O' Hara, Graham [Murdoch University, Perth, Australia; Chain, Patrick S. G. [Lawrence Livermore National Laboratory (LLNL); Ardley, Julie [Murdoch University, Perth, Australia; Brau, Lambert [Murdoch University, Perth, Australia; Nandesena, Kemanthi [Murdoch University, Perth, Australia; Tiwari, Ravi [Murdoch University, Perth, Australia; Copeland, A [U.S. Department of Energy, Joint Genome Institute; Nolan, Matt [U.S. Department of Energy, Joint Genome Institute; Han, Cliff [Los Alamos National Laboratory (LANL); Brettin, Thomas S [ORNL; Land, Miriam L [ORNL; Ovchinnikova, Galina [U.S. Department of Energy, Joint Genome Institute; Ivanova, N [U.S. Department of Energy, Joint Genome Institute; Mavromatis, K [U.S. Department of Energy, Joint Genome Institute; Markowitz, Victor [U.S. Department of Energy, Joint Genome Institute; Kyrpides, Nikos C [U.S. Department of Energy, Joint Genome Institute; Melino, Vanessa [Murdoch University, Perth, Australia; Denton, Matthew [Department of Primary Industries, Victoria, Australia; Yates, Ron [Murdoch University, Perth, Australia; Howieson, John [Murdoch University, Perth, Australia

    2010-01-01

    Rhizobium leguminosarum bv trifolii is a soil-inhabiting bacterium that that has the capacity to be an effective nitrogen fixing microsymbiont of a diverse range of annual Trifolium (clover) species. Strain WSM1325 is an aerobic, motile, non-spore forming, Gram-negative rod isolated from root nodules collected in 1993 from the Greek Island of Serifos. WSM1325 is manufactured commercially in Australia as an inoculant for a broad range of annual clovers of Mediterranean origin due to its superior attributes of saprophytic competence, nitrogen fixation and acid-tolerance. Here we describe the basic features of this organism, together with the complete genome sequence, and annotation. This is the first completed genome sequence for a microsymbiont of annual clovers. We reveal that its genome size is 7,418,122 bp encoding 7,232 protein-coding genes and 61 RNA-only encoding genes. This multipartite genome contains 6 distinct replicons; a chromosome of size 4,767,043 bp and 5 plasmids of size 828,924, 660,973, 516,088, 350,312 and 294,782 bp.

  16. Maize growth promotion by inoculation with Azospirillum brasilense and metabolites of Rhizobium tropici enriched on lipo-chitooligosaccharides (LCOs).

    Marks, Bettina Berquó; Megías, Manuel; Ollero, Francisco Javier; Nogueira, Marco Antonio; Araujo, Ricardo Silva; Hungria, Mariangela

    2015-12-01

    There is an increasing interest in the development and use of inoculants carrying plant growth-promoting bacteria (PGPB) in crops of agronomic interest. The great majority of the inoculants commercialized worldwide contain rhizobia for legume crops, but the use of PGPB as Azospirillum spp. for non-legume is expanding, as well as of inoculants combining microorganisms and microbial metabolites. In this study we evaluated the effects of inoculants containing Azospirillum brasilense with or without metabolites of Rhizobium tropici strain CIAT 899 highly enriched in lipo-chitooligosaccharides (LCOs) in six field experiments performed for three summer crop seasons in Brazil with maize (Zea mays L.). Inoculants and metabolites were applied either at sowing by seed inoculation, or by leaf spray at the V3 stage of plant growth. Improvement in shoot dry weight (SDW) and total N accumulated in shoots (TNS) by single, but especially by dual inoculation was observed in some of the experiments. Statistically significant increases in grain yield in relation to the non-inoculated control were observed in five out of six experiments when maize was inoculated with Azospirillum supplied with enriched metabolites of R. tropici applied by seed or leaf spray inoculation. The results give strength to the development of a new generation of inoculants carrying microorganisms and microbial molecules. PMID:26567001

  17. Final environmental statement related to the operation of Catawba Nuclear Station, Units 1 and 2. Docket Nos. 50-413 and 50-414, Duke Power Company, et al

    This Final Environmental Statement contains the second assessment of the environmental impact associated with the operation of the Catawba Nuclear Station, Units 1 and 2, pursuant to the National Environmental Policy Act of 1969 (NEPA) and 10 CFR 51, as amended, of the NRC regulations. This statement examines: the affected environment, environmental consequences and mitigating actions, and environmental and economic benefits and costs. Land use and terrestrial and aquatic-ecological impacts will be small. Operational impacts to historic and archeological sites will be negligible. The effects of routine operations, energy transmission, and periodic maintenance of rights-of-way and transmission facilities should not jeopardize any populations of endangered or threatened species. No significant impacts are anticipated from normal operational releases of radioactivity. The risk associated with accidental radiation exposure is very low. The net socioeconomic effects of the project will be beneficial

  18. C. Petrone et al.: "Magnetic measurement of the model magnet QD0 designed for the CLIC final focus beam transport line." CERN TE-MSC Internal Note, EDMS Nr: 1184196

    Arpaia, Pasquale; Petrone, Carlo; Russenschuck, Stephan; Walckiers, Louis

    2012-01-01

    This note presents the results of the magnetic measurements performed on QD0, model magnet for the final focus transport line for CLIC (Fig. 1). This high-gradient, hybrid quadrupole has a yoke length of 0.1 m and an aperture of 8.3 mm. ND2Fe14B Permanent magnet blocks provide a gradient of 150 T/m, which can be further increased to 530 T/m when the four coils are excited to 18.3 A. The request was to measure the strength of the field and the multipole coefficients at different currents. The measurement of the field strength, by means of the single stretched wire system, was done in December 2011 in the I8 laboratory. The measurement of the multipole was done by means of the oscillating wire system [1][2].

  19. Cartographie et intelligence artificielle

    Denise Pumain

    2005-11-01

    Full Text Available Le monde complexe dans lequel nous évoluons est aussi paradoxal : ainsi, que peut-on prédire quant à la diffusion du savoir faire des géographes en termes de cartographie et de visualisation de l’information géographique ? On voit surgir toujours plus d’instruments et d’occasions de se repérer et d’admirer des images de la terre, mais il n’est pas sûr que cela fasse progresser dans le public la connaissance des cartes et de leur interprétation. Prenons l’exemple du repérage, par GPS, et bient...

  20. Villes et nouvelle économie

    Emmanuel Éveno

    2003-06-01

    Full Text Available Cet article analyse les modes d’insertionspatiale des technologies de l’information et de la communication (TIC dans les métropoles puis aborde la question des mythes d’une «antigéographie» soulevés par cette nouvelle vague d’innovations dont les postulats sont basés sur les effets de réseaux et les technologies de lutte contre la distance. Trois approches (hiérarchie urbaine, réorganisation de l’espace métropolitain, nouveaux objets urbains essaient de montrer toute la place de la géographie et des problématiques territoriales autour des TIC.

  1. Durkheim et le Collectivisme.

    Didry, Claude

    2015-01-01

    Ce texte est issu d'une intervention au colloque "DROIT ET SOCIOLOGIE (1860-1939).?Moment juridique de la sociologie ou moment sociologique du droit?", organisé les 20 et 21 juin 2013 par Mélanie Plouviez et Frédéric Audren. Il propose un retour sur les différentes formes d'appropriation de la sociologie durkheimienne, dans un objectif réformiste, en mettant notamment au jour l'importante contribution de Jaurès qui dans sa présentation de la société collectiviste de l'avenir, se fonde sur la ...

  2. Abeilles sauvages et pollinisation

    Pfiffner, Lukas; Müller, Andreas

    2016-01-01

    La publication résume l’état actuel des connaissances scientifiques sur l’importance des abeilles sauvages dans la pollinisation des plantes sauvages et cultivées. Elle cite les causes actuellement connues du recul des abeilles sauvages, présente l’effet de l’agriculture biologique et propose une liste de mesures destinées à favoriser et à protéger ces pollinisateurs en plus de celles qui sont déjà appliquées.

  3. A 13C-NMR study of exopolysaccharide synthesis in Rhizobium meliloti Su47 strain

    Tavernier, P.; Portais, J.-C.; Besson, I.; Courtois, J.; Courtois, B.; Barbotin, J.-N.

    1998-02-01

    Metabolic pathways implied in the synthesis of succinoglycan produced by the Su47 strain of R. meliloti were evaluated by 13C-NMR spectroscopy after incubation with [1{-}13C] or [2{-}13C] glucose. The biosynthesis of this polymer by R. meliloti from glucose occurred by a direct polymerisation of the introduced glucose and by the pentose phosphate pathway. Les voies métaboliques impliquées dans la synthèse du succinoglycane produit par la souche Su47 de R. meliloti ont été évaluées par la spectroscopie de RMN du carbone 13 après incubation des cellules avec du [1{-}13C] ou [2{-}13C] glucose. La biosynthèse de ce polymère à partir du glucose se produit par polymérisation directe du glucose et par la voie des pentoses phosphate.

  4. Isolation and identification of an EPS-producing Rhizobium strain from arid soil (Algeria): characterization of its EPS and the effect of inoculation on wheat rhizosphere soil structure.

    Kaci, Yahia; Heyraud, Alain; Barakat, Mohamed; Heulin, Thierry

    2005-05-01

    The production of exopolysaccharides (EPSs) by bacterial populations in the rhizosphere has been demonstrated to contribute to water and nutrient uptake by plant roots through the modification of the physical properties of rhizosphere soil. We report here the characterization of a new EPS produced by a bacterial strain (KYGT207) isolated from an arid soil in southern Algeria (Gassi Touil), and the effect of inoculation of this strain on soil physical properties in the rhizosphere of Triticum durum L. Strain KYGT207 was assigned to the genus Rhizobium by 16S ribosomal DNA sequencing and belongs to a new species closely related to Rhizobium sullae. The EPS produced by this strain was found to be composed of glucose (Glc), galactose (Gal), and mannuronic acid (ManA) in a molar ratio of 2:1:1. The primary structure of the EPS was determined by sugar analysis, 1D and 2D NMR spectroscopy, consisting of a tetrasaccharide repeating unit with the following original structure: [structure: see text]. A rheological analysis showed that this EPS could be considered as a thickening agent with polyelectrolyte properties. Inoculation of wheat plantlets with strain KYGT207 caused significant promotion of plant growth (+85% for shoot dry mass and +56% for root dry mass), a significant increase in root-adhering soil (RAS) dry mass (dm) per root dm (RAS/RT) up to 137%, and in RAS aggregate water stability. We demonstrate that EPS-producing bacteria were present in sandy soils subjected to water stress and that EPS-producing Rhizobium populations play an important role in the rhizosphere through their contribution to soil aggregation. PMID:15862451

  5. “Item perrexil, mostarda, lechugas et rauanos”. Notas sobre la alimentación de mineros alemanes en Pamplona a finales del siglo XIV (1392

    Serrano Larráyoz, Fernando

    2008-06-01

    Full Text Available The present article represents an approximation to the food of some German miners settled in Pamplona at the end of the 14th century, to carry out a series of assays intended to determine the kind of metals present in the ore and their actual proportion, with the purpose to verify the profitability of some seams found at Five Villages. Their food accounting for approximately one and a half months, give us first hand information of their habits and of those sharing the table with them. To a certain extent, it is possible to extrapolate these practices to the ones of part of Navarra's salary earners. In them, we could sense certain customs or preferences characteristic of North Europe.

    El presente artículo es una aproximación a la alimentación de unos mineros alemanes que, a finales del siglo XIV, se asientan en Pamplona con el fin de realizar una serie de ensayos (averiguación de los metales que contiene la mena —el mineral metalífero—, y la proporción en que cada uno está con el peso de ella en los que determinar la rentabilidad de algunos filones mineros encontrados en la zona de las Cinco Villas. Las cuentas de los gastos que realizan en alimentación, en aprox. mes y medio, nos acercan de primera mano a los hábitos de estos hombres y de quienes les acompañan en la mesa. Unas prácticas que es posible extrapolar, en cierta medida, a parte de la menestralía navarra, y en las que podemos intuir ciertas costumbres (o gustos propios de la Europa del Norte.

  6. Caliban et ses avatars

    Andrews, Malcolm; BESSON, Françoise; Birgy, Philippe; Bouyssou, Roland; Breteau, Jean-Louis; Camus, Cyril; Costa de Beauregard, Raphaelle; Débax, Jean-Paul; Doumerc, Eric; Editors, The; Fioupou, Christiane; Fletcher, John; Gauffre, Marie-Jeanne; Harding, Wendy; Kantarbaeva-Bill, Irina

    2015-01-01

    Ce numéro de Caliban, réalisé à l’occasion du cinquantenaire de la revue née en 1964, aborde le personnage de Caliban dans la pièce de Shakespeare La Tempête à travers le texte et diverses mises en scène, mais aussi ses implications dans ses réécritures et réappropriations, que ce soit dans l’écriture de la négritude, les cultures africaines, amérindiennes ou caribéennes, du théâtre à la poésie et des arts visuels – peinture, cinéma, bande dessinée – au roman, à la littérature de la nature et...

  7. Convexité et Optimisation

    Cohen, Guy

    2000-01-01

    Préface Introduction Éléments d'analyse fonctionnelleEnsembles convexesFonctions convexesOptimisation sous contraintes : conditions d'optimalité localesConditions d'optimalité globales et techniques LagrangiennesLagrangien augmenté

  8. Lipochimie et innovations

    Alfos Carine

    2003-01-01

    Peut-on parler d’un nouvel âge d’or pour les produits à base de ressources végétales renouvelables et notamment pour les huiles ? Porteurs de performances spécifiques et de caractéristiques plus écologiquement correctes, leur emploi ouvre à l’industrie un potentiel d’innovations auquel participe le département de chimie et rhéologie de l’Iterg. La prise de conscience collective, associée aux évolutions des réglementations françaises et européennes, devrait conduire les industries à prendre de...

  9. Isolation and characterization of a DNA replication origin from the 1,700-kilobase-pair symbiotic megaplasmid pSym-b of Rhizobium meliloti.

    Margolin, W.; Long, S R

    1993-01-01

    A 4-kb fragment active as an autonomously replicating sequence (ARS) from the Rhizobium meliloti symbiotic megaplasmid pSym-b was isolated by selecting for sequences that allowed a normally nonreplicative pBR322 derivative to replicate in R. meliloti. The resulting Escherichia coli-R. meliloti shuttle plasmid (mini-pSym-b) containing the ARS also replicated in the closely related Agrobacterium tumefaciens, but only in strains carrying pSym-b, suggesting that a megaplasmid-encoded trans-acting...

  10. Characterization of genes for synthesis and catabolism of a new rhizopine induced in nodules by Rhizobium meliloti Rm220-3: extension of the rhizopine concept.

    Saint, C. P.; Wexler, M.; Tempé, J; Tate, M E; Murphy, P J

    1993-01-01

    Rhizopines are selective growth substrates synthesized in nodules only by strains of rhizobia capable of their catabolism. We report the isolation and study of genes for the synthesis and catabolism of a new rhizopine, scyllo-inosamine (sIa), from alfalfa nodules induced by Rhizobium meliloti Rm220-3. This compound is similar in structure to the previously described rhizopine 3-O-methyl-scyllo-inosamine from R. meliloti L5-30 (P.J. Murphy, N. Heycke, Z. Banfalvi, M.E. Tate, F.J. de Bruijn, A....

  11. Isolation and characterization of mutants of Rhizobium leguminosarum bv. viciae 248 with altered lipopolysaccharides: possible role of surface charge or hydrophobicity in bacterial release from the infection thread.

    Maagd, R.A., de; Rao, A. S.; Mulders, I H; Goosen-de Roo, L; Loosdrecht, M.C., van; Wijffelman, C. A.; Lugtenberg, B J

    1989-01-01

    Effects of alterations in lipopolysaccharide (LPS) structure of Rhizobium leguminosarum bv. viciae on effective symbiosis and on a number of cell surface characteristics were studied. Tn5 mutants with altered LPSs were screened for their inability to bind monoclonal antibody 3, one of three monoclonal antibodies to the tentative O-antigenic part of the wild-type LPS of strain 248. Ten class I LPS mutants completely lacked the O-antigen-containing LPS species. The class II LPS mutant had a sev...

  12. Conservation of PcaQ, a transcriptional activator of pca genes for catabolism of phenolic compounds, in Agrobacterium tumefaciens and Rhizobium species.

    Parke, D

    1996-01-01

    In Agrobacterium tumefaciens A348, control of five genes for catabolism of the phenolic compound protocatechuate to beta-ketoadipate is exerted by the gene pcaQ. The product of pcaQ is a transcriptional activator which is distinct from regulators of the beta-ketoadipate pathway characterized in other bacterial groups. An investigation of whether pcaQ is present and conserved in related Rhizobium species employed Southern hybridization and an agrobacterial pcaD::LacZ promoter probe plasmid. Th...

  13. Analysis of Poly-β-Hydroxybutyrate in Rhizobium japonicum Bacteroids by Ion-Exclusion High-Pressure Liquid Chromatography and UV Detection †

    Karr, Dale B.; Waters, James K.; Emerich, David W.

    1983-01-01

    Ion-exclusion high-pressure liquid chromatography (HPLC) was used to measure poly-β-hydroxybutyrate (PHB) in Rhizobium japonicum bacteroids. The products in the acid digest of PHB-containing material were fractionated by HPLC on Aminex HPX-87H ion-exclusion resin for organic acid analysis. Crotonic acid formed from PHB during acid digestion was detected by its intense absorbance at 210 nm. The Aminex-HPLC method provides a rapid and simple chromatographic technique for routine analysis of org...

  14. Development of a Real-Time PCR Assay for Detection and Quantification of Rhizobium leguminosarum Bacteria and Discrimination between Different Biovars in Zinc-Contaminated Soil▿

    Macdonald, Catriona A.; Clark, Ian M; Hirsch, Penny R.; Zhao, Fang-Jie; McGrath, Steve P.

    2011-01-01

    Primers were designed to target 16S rRNA and nodD genes of Rhizobium leguminosarum from DNA extracted from two different soil types contaminated with Zn applied in sewage sludge. Numbers of rhizobia estimated using 16S rRNA gene copy number showed higher abundance than those estimated by both nodD and the most-probable-number (MPN) enumeration method using a plant trap host. Both 16S rRNA gene copies and the MPN rhizobia declined with increased levels of Zn contamination, as did the abundance...

  15. [Influence of calcium and rhizobial infections (Rhizobium leguminosarum) on the dynamics of nitric oxide (NO) content in roots of etiolated pea (Pisum sativum L.) seedlings].

    Glian'ko, A K; Ishchenko, A A; Stepanov, A V

    2014-01-01

    The effect of exogenous calcium (Ca2+) and rhizobial infections (Rhizobium leguminosarum bv viceae) on the dynamics of the level of nitric oxide (NO) was studied in cross cuts of roots of two-day-old etiolated pea seedlings (Pisum sativum L.) using a DAF-2DA fluorescent probe. Fluctuations of the NO level, indicating the presence of a rhythm in the generation of NO in roots, were observed during the incubation of seedlings in water, a CaCl2 solution, and with rhizobial infections. Exogenous factors (Ca2+ and two rhizobial stamms) change the time dynamics of the NO level in comparison with the control (water). PMID:25726667

  16. Caracterización de una permeasa de Rhizobium leguminosarum en el transporte de molibdeno y en la simbiosis con guisantes.

    Alaminos Hervás, Elena

    2011-01-01

    Rhizobium leguminosarum es una bacteria que establece relaciones simbióticas con guisantes gracias a la fijación de nitrógeno en unas estructuras radiculares llamadas nódulos. La nitrogenasa es la enzima responsable de fijar nitrógeno y necesita molibdeno para su funcionamiento. Estudios recientes en otra bacteria, Rhodobacter capsulatus, han descubierto que existe una permeasa, PerO, implicada en el transporte de molibdeno al interior celular. En nuestro equipo de investigación disponemos ...

  17. Forestación de un terreno decapitado con Robinia pseudoacacia inoculada con Rhizobium spp. y Glomus deserticola Afforestation of a desurfaced field with Robinia pseudoacacia inoculated with Rhizobium spp. and Glomus deserticola

    Alejandro E Ferrari

    2010-07-01

    Full Text Available Los terrenos decapitados constituyen un caso extremo de degradación de suelos aptos para agricultura, con graves consecuencias ambientales. El propósito de este trabajo fue ensayar los efectos de la inoculación de acacia blanca (Robinia pseudoacacia L. con una cepa efectiva de Rhizobium y un hongo de micorrizas arbusculares (Glomus deserticola en la supervivencia y crecimiento temprano de plantas trasplantadas a un terreno decapitado de Balcarce, comparando con fresno como árbol no fijador de nitrógeno. La supervivencia inicial fue muy buena (mayor del 77%, especialmente para los fresnos y las acacias inoculadas, las cuales mostraron significativamente mayor supervivencia al estrés por sequía que las acacias control. Todas las plantas se mostraron igualmente tolerantes al ataque de liebres y al estrés por heladas tardías. Durante el primer año las acacias inoculadas crecieron más rápido que las no inoculadas. En el segundo año las alturas se equipararon en parte, probablemente por la colonización de las acacias control con rizobios o micorrizas naturales del suelo. De todos modos, las acacias inoculadas siempre mostraron valores mayores de los distintos parámetros de desarrollo (altura total, diámetro de la copa y cantidad de ramificaciones que las plantas control, tanto en los sectores poco decapitados como en los más severamente degradados. En conclusión, la doble inoculación previa de acacia blanca mejoró la supervivencia inicial, aumentó tolerancia a la sequía y el crecimiento en 2 años y medio desde la plantación. Esta práctica de manejo sería entonces muy recomendable para reducir el período de vivero en la producción de árboles, así como lograr ejemplares más resistentes y mejor adaptados para proyectos de recuperación de suelos degradados.Many agricultural lands in Buenos Aires Province (Argentina have traditionally been desurfaced for the manufacture of bricks and other building materials. The desurfaced soils represent an extreme situation of degradation, having severe consequences for the environment. The purpose of this work was to assay the effects of inoculation of black locust (Robinia pseudoacacia L. with Rhizobium and with a mycorrhizal strain on the survival and early growth of plants in a desurfaced field at the location of Balcarce (37º 45´ S, 58º 18´ O, in Buenos Aires Province (Argentina. The development of inoculated black locust was compared with non-inoculated (control black locust and with the non-fixing green ash (Fraxinus pennsylvanica Marsh.. Survival after two months was very good (>77%, especially for Fraxinus and for inoculated plants. Furthermore, inoculated plants also showed a significantly higher survival rate under drought stress than the control plants. The three kinds of plants showed high tolerance to hare attack and to late frost stress. During the first year, inoculated plants grew more rapidly than non-inoculated controls. During the second year the height of the two treatments was quite similar, probably because of the nodulation of control plants with soil-borne rhizobial or mycorrhizal strains. However, inoculated plants always showed higher development than the control plants according to three growth parameters (total height, canopy diameter and amount of side branches, both in the intact parts of the field and in the most severely extracted sectors. In conclusion, prior inoculation of black locust with effective strains of Rhizobium and mycorrhizal fungi was able to improve initial survival, tolerance to drought and early growth. This management practice is highly recommended to reduce the greenhouse period in the production of trees, and to produce plants more resistant and better adapted to use in reclamation projects of degraded areas.

  18. DÉRIVATION ALLEMANDE ET TRADUCTION

    Silvia BONCESCU

    2011-01-01

    Dans le domaine du lexique allemand, la dérivation, qui n’utilise pas forcément préfixes et suffixes dans leur sens traditionnel, témoigne d’une grande vitalité des structures lexicales, notamment dans la langue de la presse. Nous étudierons de plus près des exemples tirés d’un corpus de presse écrite et nous verrons quelles sont les difficultés de traduction auxquelles nous nous confrontons.

  19. Gestion et mondialisation

    Jean-Luc Metzger

    2010-10-01

    Full Text Available L’économie mondiale est en crise. Apparue dans la sphère financière globalisée, cette « crise » se serait propagée à l’économie réelle planétaire, laquelle, pour s’adapter, exige des élites politiques qu’elles interviennent et encouragent la mise en œuvre d’instruments de gestion portant sur l’emploi, l’organisation du travail ou les relations avec les différents marchés (clients et fournisseurs. Une telle vision, dominante, naturalise la production des dynamiques contemporaines. Elle présen...

  20. Entrepreneuriat Social et Participation Citoyenne

    Sophie Larivet

    2010-01-01

    Full Text Available L'entrepreneuriat social est un concept émergeant, notamment dans les sciences de l'administration. Pourtant, en dehors d'une pratique directoriale spécifique, il est aussi une forme de participation citoyenne trop méconnue. L'objectif de cet article, basé sur une revue de la littérature et une approche théorique, est de présenter le concept d'entrepreneuriat social afin de mieux saisir son positionnement par rapport à la participation citoyenne. L'entrepreneuriat social constitue une forme particulière de participation à l'espace public par l'action, les entreprises sociales agissant au quotidien pour transformer le paysage social. En particulier, cet article souligne le contexte de développement de l'entrepreneuriat social, définit le concept et les notions connexes d'entreprise sociale et d'entrepreneur social, et, enfin, présente une réflexion sur la contribution de l'entrepreneuriat social à la participation citoyenne. L'article montre que l'entrepreneuriat social est une façon pour les citoyens d'agir directement et avec maîtrise sur la société. / Social entrepreneurship is an emerging concept, notably in administrative sciences. However, not only is it a specific managerial practice but it is also a type of citizen participation that is not well-known. The objective of this article, based on a literature review and a theoretical approach, is to present the concept of social entrepreneurship in order to better understand its relation to citizen participation. Social entrepreneurship represents a specific type of citizen participation involving actions. Social enterprises act daily to transform the social landscape. More specifically, this article presents the context of development of social entrepreneurship, proposes a definition of the concept and of other connected notions like "social enterprise" and "social entrepreneur", and, finally, analyzes the contribution of social entrepreneurship to citizen participation. It shows that social entrepreneurship is a way for citizens to act directly and with some power on society.

  1. Le beau et le vrai

    Létitia Mouze

    2006-05-01

    Full Text Available La vie des abeilles de Maeterlinck est un ouvrage à la fois scientifique et littéraire, non pas parce qu’il appartiendrait à la science par son exactitude et à la littérature par son style, mais en ce qu’il invite à penser l’unité des deux domaines. Les aspects littéraires de l’ouvrage (beauté de l’écriture, usage des images, de l’analogie, etc. ne sont pas des accessoires, mais des outils indispensables à l’élaboration d’un authentique savoir sur les abeilles, c’est-à-dire un savoir qui reconnaît la part d’inconnu et le mystère qui subsistent en dépit de toutes les explications physiques et mécaniques que l’on peut par ailleurs donner des phénomènes observés. Etre scientifique, dans cette perspective, c’est-à-dire donner à connaître, c’est donc être littéraire. Cette conception de la science repose en dernière instance sur une conception philosophique de l’univers comme un tout où toutes choses sont reliées, unies, par des relations d’analogies, ce qui fonde et justifie l’emploi d’un style symboliste.The life of bees, one of Maeterlinck’s works, is together a scientific and literary book, not because of it scientific exactness and its literary style, but for the reason it suggests the unity of both these domains. Literay’s aspects of this work (writing’s beauty, use of images, analogy, etc. are not secondary but necessary to elaborate an authentic knowledge about bees, that means a knowledge which admit the unknown part and the mistery that subsist despite all the physical and mechanical explanations we can give moreover about the observed phenomenons. Be a scientist, in this sense, that is give something to know, therefore means be literary. Finally, this conception of science consist in a philosophiacl conception of Universe as a whole where everything links together, and is united by analogical relations, that base and justify the use of a symbolist style.

  2. Topographie et topologie textuelles

    Jean-Louis Lebrave

    2009-11-01

    Full Text Available Depuis ses débuts la statistique linguistique, y compris lorsqu’elle s’applique à l’étude des textes et des discours, a principalement recouru à des modèles qui tendent à négliger ce fait majeur qu’un texte est une structure ordonnée ; les dénombrements, les relevés de fréquences, les calculs de spécificités reposent tous sur le fameux schéma d’urne et renoncent à prendre en compte le positionnement dans le texte des unités dénombrées. Certes, les résultats ainsi obtenus sont généralement intéressants et bien interprétables, et ils ont largement contribué au développement et aux succès de la discipline. Mais ils se pourraient qu’ils soient en train d’atteindre leurs limites. Ou, du moins, de ne plus suffire pour donner entière satisfaction au chercheur. De plus en plus souvent en effet, ceux-ci souhaitent pouvoir établir, à côté de la dimension paradigmatique appréhendée par ce type de calculs statistiques traditionnels, la dimension syntagmatique des données textuelles, saisies à courte ou à longue portée : distribution régulière ou non d’une entité linguistique (mot ou catégorie grammaticale susceptible d’arriver à intervalles à peu près égaux ou, au contraire, en paquets plus ou moins denses ; répartition d’un élément au fil du texte, selon la structure globale de celui-ci et ses parties constituantes ; phénomènes d’échos et d’alignements dans la mise en parallèle de deux textes ou deux portions de textes ; etc. Bien sûr, des travaux, dont certains sont déjà anciens, ont abordé ces questions : parmi les plus connus citons tous ceux d’A. Salem qui ont établi la pertinence de la fameuse notion de « segment répété » et qui ont mis en place les outils pour les repérer et les analyser ; citons aussi les travaux de P. Lafon sur les « rafales » et son article "Statistique des localisations des formes d’un texte" paru en 1984 dans la revue Mots ; ou encore l’article de D. Sérant et Ph. Thoiron sur la « topographie des formes répétées » (Revue Informatique et Statistique dans les Sciences humaines 24, pp. 333-343 ; etc. Actuellement, cette question reprend de l’acuité et les études, ainsi que les développements logiciels afférents, se multiplient. Le moment nous semble donc venu de faire le point. Ce numéro de Lexicometrica accueillera donc exclusivement des contributions consacrées aux notions de topographie et topologie textuelles, c’est-à-dire à la prise en compte, dans les exploitations automatiques des textes numérisés et dans leur traitement quantitatif de la linéarité intrinsèque du texte, voire de sa structure en réseau avec d’autres textes au sein d’un corpus fortement cohérent (cas des recueils par exemple.

  3. Greenhouse effect gases sources and sinks (CO{sub 2}, CH{sub 4}, N{sub 2}O) in grasslands and reduction strategies. Greenhouse effect gases prairies. Final report of the second part of the project. April 2004; Sources et puits de gaz a effet de serre (CO{sub 2}, CH{sub 4}, N{sub 2}O) en prairie paturee et strategies de reduction. GES-Prairies. Rapport final de la seconde tranche du projet. Avril 2004

    Soussana, J.F

    2004-04-15

    The project 'GES-Prairies' (Greenhouse Gases - Grasslands) had two main objectives: 1. To measure more accurately the fluxes of CO{sub 2}, CH{sub 4} and N{sub 2}O of French grasslands and determine the greenhouse gas (GHG) balance of these areas. 2. To calculate the net GHG emissions of cattle production farms and finally to propose and evaluate some management scenarios leading to a reduction of GHG emissions. This project deals with three different spatial scales: the field scale, the farm scale and finally, the regional scale. At the field scale, during two years, fluxes of CO{sub 2}, CH{sub 4} and N{sub 2}O were measured in a mid-mountain permanent grassland, previously managed intensively by cutting and grazing (Laqueuille, Auvergne, France). Results from the first complete year of measurements show that the extensification process (reduction of the stocking rate and stopping N fertilization) allows to stock more carbon in the ecosystem. At the farm scale, We developed a model (FARMSIM, coupled to PASIM) able to simulate the GHG balance of a livestock farm. FARMSIM has been tested with data obtained from a mixed livestock farm in Lorraine (dairy and meat production, annual average stocking rate = 1.3 LU ha{sup -1}) of 100 ha (including 76 ha of grasslands and 21 of annual crops). The results indicate a net emission of 175 t equivalent C-CO{sub 2} for this farm. If expressed per unit of product, it represents 1.34 t equivalent C-CO{sub 2} per LU and per year or 0.54 kg CO{sub 2} per kg of milk and per year. At the regional scale/. The PASIM model has been used to simulate the European grasslands with a spatial resolution of 1' (about 200 * 200 km). For each grid cell, a sensibility analysis allowed to determine the N application which correspond to 30% of the N application that would maximize the annual yield of the pasture. Simulation runs on mixed systems (combining grazing and cutting) show that almost one half of the grassland area is, on average, used for cutting. These simulations predict N{sub 2}O emission factors that are relatively stable for the different grid cells across Europe wit values ranging between 1 and 2% in cut systems and between 3 and 4% under grazing (with organic N application through faeces and urine deposition). Under cutting, the simulations predict a important annual C storage (varying between 0.5 to 6 t C ha-1 y-1). However one must consider that an important part of this storage occurs in the harvested forage. C storage in grazed grasslands (0.3 to 2 t C ha-1 y-1) is lower than in cut grasslands. The simulations indicates therefore that cut grassland could represent an important net GHG sink. In France, the amplitude of this sink could vary between 0.5 and 2 t C CO{sub 2} equivalent ha-1 y-1. The simulations combining cut and grazed grassland, in proportion to the dietary needs, show that,in France, these systems would be a net GHG sink of 2 to 3 t C CO{sub 2} equivalent ha-1 y-1. More realistic results would be obtained if the differences between farming systems were taken into account more specifically. (author)

  4. Biodegradation of Selected Nigerian Fruit Peels by the use of a Non-pathogenic Rhizobium species CWP G34B.

    Esther Boboye, Bolatito; Ajayi, George Olarewaju

    2012-01-01

    This study was carried out to determine the ability of Rhizobium species CWP G34B to degrade the peels of selected Nigerian fruits. The potential of the bacterium to digest some carbon sources (lactose, maltose, sucrose and mannitol) and peels of some Nigerian fruits (pineapple, orange, plantain, banana, pawpaw and mango fruits) was investigated by growing the organism on the substances separately after which DNSA reagent method was used to quantify glucose released into the medium. The results showed that the bacterium was able to degrade all the carbohydrates with the highest and the lowest glucose concentrations of 5.52 mg/ml for lactose and 0.50 mg/ml for mannitol. The carbohydrate-catabolic-enzyme (CCE) activity ranged from 0.169 mg/ml to 1.346 mg/ml glucose per mg/ml protein. Mannitol exhibited the highest CCE activity while the lowest activity was observed in the presence of sucrose. The amount of extracellular protein synthesized was highest (9.803 mg/ml) in the presence of maltose and lowest (0.925 mg/ml) in mannitol. The mean polygalacturonase activity was 0.54 unit/ml when the bacterium was grown in pectin in contrast to 0.28 unit/ml when it was grown in mannitol. The bacterium showed ability to breakdown the peels of the Nigerian fruits with the highest capability in banana and pineapple (0.42 and 0.41 mg/ml glucose per mg/ml protein respectively). The fruit-peel-degrading enzyme activity was lowest in orange peel (0.75 unit/ml). PMID:23166567

  5. Rhizobium leguminosarum bv. trifolii rosR is required for interaction with clover, biofilm formation and adaptation to the environment

    Piersiak Tomasz

    2010-11-01

    Full Text Available Abstract Background Rhizobium leguminosarum bv. trifolii is a symbiotic nitrogen-fixing bacterium that elicits nodules on roots of host plants Trifolium spp. Bacterial surface polysaccharides are crucial for establishment of a successful symbiosis with legumes that form indeterminate-type nodules, such as Trifolium, Pisum, Vicia, and Medicago spp. and aid the bacterium in withstanding osmotic and other environmental stresses. Recently, the R. leguminosarum bv. trifolii RosR regulatory protein which controls exopolysaccharide production has been identified and characterized. Results In this work, we extend our earlier studies to the characterization of rosR mutants which exhibit pleiotropic phenotypes. The mutants produce three times less exopolysaccharide than the wild type, and the low-molecular-weight fraction in that polymer is greatly reduced. Mutation in rosR also results in quantitative alterations in the polysaccharide constituent of lipopolysaccharide. The rosR mutants are more sensitive to surface-active detergents, antibiotics of the beta-lactam group and some osmolytes, indicating changes in the bacterial membranes. In addition, the rosR mutants exhibit significant decrease in motility and form a biofilm on plastic surfaces, which differs significantly in depth, architecture, and bacterial viability from that of the wild type. The most striking effect of rosR mutation is the considerably decreased attachment and colonization of root hairs, indicating that the mutation affects the first stage of the invasion process. Infection threads initiate at a drastically reduced rate and frequently abort before they reach the base of root hairs. Although these mutants form nodules on clover, they are unable to fix nitrogen and are outcompeted by the wild type in mixed inoculations, demonstrating that functional rosR is important for competitive nodulation. Conclusions This report demonstrates the significant role RosR regulatory protein plays in bacterial stress adaptation and in the symbiotic relationship between clover and R. leguminosarum bv. trifolii 24.2.

  6. Regulation of exopolysaccharide synthesis in Rhizobium sp. strain TAL1145 involves an alternative sigma factor gene, rpoH2.

    Kaufusi, Pakieli H; Forsberg, L Scott; Tittabutr, Panlada; Borthakur, Dulal

    2004-10-01

    Exopolysaccharide (EPS) produced by Rhizobium sp. strain TAL1145 has been shown to be essential for effective nodulation on Leucaena leucocephala (leucaena). This paper reports the isolation and characterization of an alternative sigma factor gene, rpoH2, involved in the regulation of EPS synthesis in TAL1145. Disruption of this gene in TAL1145 resulted in a Calcofluor-dim mutant RUH102 that produced approximately 18 % of the amount of EPS made by TAL1145. This mutation did not affect the normal growth of RUH102 in free-living state. RUH102 induced few nitrogen-fixing nodules, resulting in a significant reduction in total nitrogen content in leucaena. It was complemented for EPS production and nodulation by a 2.0 kb HindIII fragment of TAL1145. Sequence analysis of this fragment revealed the rpoH2 ORF of 870 bp that encoded a protein of 32 kDa. Expression of the rpoH2 ORF in Escherichia coli also revealed a 32 kDa protein. A PCR-constructed clone of 1263 bp, containing the rpoH2 ORF and its upstream putative regulatory region, complemented RUH102 for EPS defects. Comparison of the RpoH2 sequence to proteins in the databases showed significant similarity to RpoH-like sigma factors of other Gram-negative bacteria. By constructing several exo : : Tn3Hogus fusions and transferring them to the backgrounds of TAL1145 and RUH102, it was demonstrated that RpoH2 positively regulates the transcription of some exo genes. PMID:15470124

  7. PssP2 is a polysaccharide co-polymerase involved in exopolysaccharide chain-length determination in Rhizobium leguminosarum.

    Marczak, Ma?gorzata; Matysiak, Paulina; Kutkowska, Jolanta; Skorupska, Anna

    2014-01-01

    Production of extracellular polysaccharides is a complex process engaging proteins localized in different subcellular compartments, yet communicating with each other or even directly interacting in multicomponent complexes. Proteins involved in polymerization and transport of exopolysaccharide (EPS) in Rhizobium leguminosarum are encoded within the chromosomal Pss-I cluster. However, genes implicated in polysaccharide synthesis are common in rhizobia, with several homologues of pss genes identified in other regions of the R. leguminosarum genome. One such region is chromosomally located Pss-II encoding proteins homologous to known components of the Wzx/Wzy-dependent polysaccharide synthesis and transport systems. The pssP2 gene encodes a protein similar to polysaccharide co-polymerases involved in determination of the length of polysaccharide chains in capsule and O-antigen biosynthesis. In this work, a mutant with a disrupted pssP2 gene was constructed and its capabilities to produce EPS and enter into a symbiotic relationship with clover were studied. The pssP2 mutant, while not altered in lipopolysaccharide (LPS), displayed changes in molecular mass distribution profile of EPS. Lack of the full-length PssP2 protein resulted in a reduction of high molecular weight EPS, yet polymerized to a longer length than in the RtTA1 wild type. The mutant strain was also more efficient in symbiotic performance. The functional interrelation between PssP2 and proteins encoded within the Pss-I region was further supported by data from bacterial two-hybrid assays providing evidence for PssP2 interactions with PssT polymerase, as well as glycosyltransferase PssC. A possible role for PssP2 in a complex involved in EPS chain-length determination is discussed. PMID:25268738

  8. Non-pathogenic Rhizobium radiobacter F4 deploys plant beneficial activity independent of its host Piriformospora indica.

    Glaeser, Stefanie P; Imani, Jafargholi; Alabid, Ibrahim; Guo, Huijuan; Kumar, Neelendra; Kämpfer, Peter; Hardt, Martin; Blom, Jochen; Goesmann, Alexander; Rothballer, Michael; Hartmann, Anton; Kogel, Karl-Heinz

    2016-04-01

    The Alphaproteobacterium Rhizobium radiobacter F4 (RrF4) was originally characterized as an endofungal bacterium in the beneficial endophytic Sebacinalean fungus Piriformospora indica. Although attempts to cure P. indica from RrF4 repeatedly failed, the bacterium can easily be grown in pure culture. Here, we report on RrF4's genome and the beneficial impact the free-living bacterium has on plants. In contrast to other endofungal bacteria, the genome size of RrF4 is not reduced. Instead, it shows a high degree of similarity to the plant pathogenic R. radiobacter (formerly: Agrobacterium tumefaciens) C58, except vibrant differences in both the tumor-inducing (pTi) and the accessor (pAt) plasmids, which can explain the loss of RrF4's pathogenicity. Similar to its fungal host, RrF4 colonizes plant roots without host preference and forms aggregates of attached cells and dense biofilms at the root surface of maturation zones. RrF4-colonized plants show increased biomass and enhanced resistance against bacterial leaf pathogens. Mutational analysis showed that, similar to P. indica, resistance mediated by RrF4 was dependent on the plant's jasmonate-based induced systemic resistance (ISR) pathway. Consistent with this, RrF4- and P. indica-induced pattern of defense gene expression were similar. In clear contrast to P. indica, but similar to plant growth-promoting rhizobacteria, RrF4 colonized not only the root outer cortex but also spread beyond the endodermis into the stele. On the basis of our findings, RrF4 is an efficient plant growth-promoting bacterium. PMID:26495996

  9. Multiplicity of Sulfate and Molybdate Transporters and Their Role in Nitrogen Fixation in Rhizobium leguminosarum bv. viciae Rlv3841.

    Cheng, Guojun; Karunakaran, Ramakrishnan; East, Alison K; Poole, Philip S

    2016-02-01

    Rhizobium leguminosarum Rlv3841 contains at least three sulfate transporters, i.e., SulABCD, SulP1 and SulP2, and a single molybdate transporter, ModABC. SulABCD is a high-affinity transporter whose mutation prevented growth on a limiting sulfate concentration, while SulP1 and SulP2 appear to be low-affinity sulfate transporters. ModABC is the sole high-affinity molybdate transport system and is essential for growth with NO3(-) as a nitrogen source on limiting levels of molybdate (<0.25 μM). However, at 2.5 μM molybdate, a quadruple mutant with all four transporters inactivated, had the longest lag phase on NO3(-), suggesting these systems all make some contribution to molybdate transport. Growth of Rlv3841 on limiting levels of sulfate increased sulB, sulP1, modB, and sulP2 expression 313.3-, 114.7-, 6.2-, and 4.0-fold, respectively, while molybdate starvation increased only modB expression (three- to 7.5-fold). When grown in high-sulfate but not low-sulfate medium, pea plants inoculated with LMB695 (modB) reduced acetylene at only 14% of the wild-type rate, and this was not further reduced in the quadruple mutant. Overall, while modB is crucial to nitrogen fixation at limiting molybdate levels in the presence of sulfate, there is an unidentified molybdate transporter also capable of sulfate transport. PMID:26812045

  10. Interacción de Tsukamurella paurometabola C-924 con Rhizobium leguminosarum biovar phaseoli CFH en el cultivo de frijol

    Marieta Marín Bruzos

    2013-01-01

    Full Text Available En el estudio se evaluaron, mediante análisis de los parámetros fenológicos de las plantas, la interacción de Tsukamurella paurometabola C-924 con Rhizobium leguminosarum biovar phaseoli CFH en el cultivo de frijol. Se emplearon cuatro tratamientos: plantas sin inocular (control, inoculadas con T. paurometabola C-924, inoculadas con R. leguminosarum biovar phaseoli CFH e inoculadas con ambas cepas. Se observaron diferencias significativas (P < 0.01 en los porcentajes de germinación de las plantas tratadas con microorganismos de forma independiente o conjunta con respecto al control sin inocular. Se determinó que la inoculación de T. paurometabola C-924 afectó el proceso de nodulación de R. leguminosarum biovar phaseoli CFH. Sin embargo, esto no incidió de manera significativa en la altura de las plantas ni en el diámetro del tallo, ya que no se encontraron diferencias entre los tratamientos para estos parámetros. Para el número de hojas, los mejores resultados se obtuvieron con la aplicación de T. paurometabola C-924. Se concluyó que la interacción de T. paurometabola C-924 con R. leguminosarum biovar phaseoli CFH en el frijol estimuló significativamente la germinación de las semillas y el número de hojas de las plantas con respecto al control sin inocular. Aunque la aplicación de T. paurometabola C-924 no favoreció la nodulación de R. leguminosarum biovar phaseoli CFH, esto no afectó las características fenológicas del cultivo.

  11. Gérer et alerter

    Valérie November

    2009-03-01

    Full Text Available Sur la base de deux événements d’inondation ayant touché récemment, dans des contextes politiques, organisationnels et hydrologiques bien différents, de nouveaux quartiers d’habitation, cet article rend compte des pratiques des acteurs impliqués dans des situations d’alerte et de crise en Suisse. Le recensement des acteurs – à travers leur rôle et leur place dans les mécanismes de préparation, d’alerte et de gestion –, ainsi que l’inventaire des documents mobilisés par ceux-ci, ont été réalisés dans les deux cas. Cette analyse a permis d’évaluer la gestion des événements, de déceler les changements organisationnels qui ont suivi les crises et de connaître la conception et le degré de formalisation du risque dont étaient dotés les différents acteurs avant et après les inondations. Plus encore, l’analyse a documenté les nouveaux processus d’alerte et de prévision qui ont été mis en place suite aux événements. Il s’avère ainsi que les épisodes d’inondation agissent de façon décisive sur la production de connaissances, à un degré variable selon les acteurs. Ces épisodes révèlent aussi parfois l’existence de connaissances « en attente » qui ne sont pas encore intégrées dans les procédures institutionnelles. Tant du point de vue de la prévision que de la gestion de la crise, ils permettent aussi de tester les canaux de l’information et de combler les déficits d’organisation, de collaboration et de sécurisation des dispositifs de communication. En outre, les risques et les crises liés aux inondations modifient les dynamiques et les politiques territoriales, conséquences du réajustement des réseaux d’acteurs. La mise en place de dispositifs d’intervention et de gestion de crise se montre cependant plus efficace que la refonte des dispositifs d’aménagement, généralement longue. Toutefois, la mémoire des événements se dégradant avec le temps, une inscription territoriale du risque s’avère nécessaire.Based on two flood events that recently affected new housing areas in very different political, organisational and hydrological contexts, this article examines the practices of actors involved in emergency and crisis situations in Switzerland. In both cases, the actors are identified – through their role and their position in the various procedures related to crisis management – and an inventory is made of the documents used. The study examines how the flood events were managed, identifies the organisational changes that followed the crises, and determines how the risk was conceived and to what extent it was formalised by the different actors both before and after the floods. Finally new forecasting and warning procedures that were set up following the events are described. The study shows that floods have a decisive impact on the production of knowledge, but that this phenomenon varies according to the actors. Events such as floods also sometimes reveal the existence of "latent" knowledge, or knowledge that is available but has not yet been integrated into institutional procedures. In terms of both forecasting and crisis management, these events also provide the opportunity to test information channels and to identify and correct any problems relating to organisation, cooperation or the reliability of means of communication. Among other things, the risks and crises related to flooding modify the dynamics and policies of the local area as a result of readjustments in the networks of actors. The introduction of emergency and crisis management measures appears more effective, however, than the reorganisation of planning and development procedures, a process which generally takes a lot longer. Nevertheless, since the recollection of events tends to fade with time, it is important that risks find a more concrete form of spatial expression on the landscape.

  12. INTERACCIÓN RHIZOBIUM LEGUMINOSARUM BV TRIFOLII Y HONGOS MICORRÍCICOS EN UN ANDISOL CON DIFERENTES NIVELES DE SATURACIÓN DE ALUMINIO INTERACTION OF RHIZOBIUM LEGUMINOSARUM BV TRIFOLII AND MYCORRHIZAL FUNGI IN AN ANDISOL AT DIFFERENT LEVELS OF ALUMINIUM SATURATION

    Claudia G Castillo R

    2008-01-01

    Full Text Available La fitotoxicidad por Al es una seria limitante de la productividad de praderas crecidas sobre suelos volcánicos afectando la nodulación y efectividad de los Rhizobium. El objetivo del estudio consistió en seleccionar cepas de Rhizobium de colección para estudiar su efectividad en Trifolium repens crecido en un Andisol con cepas nativas y distinta saturación de Al. Para ello se evaluó previamente en caldo nutritivo la tolerancia a la acidez y toxicidad por Al de 12 cepas de colección mediante control de curvas de crecimiento. Paralelamente, se inocularon los Rhizobium en un Andisol para evaluar su efectividad mediante rendimiento de Trifolium pratense. Se seleccionaron las cepas R-109, R-113 y R-115 para inocularlas en el Andisol utilizando cuatro tratamientos: suelo adicionado de 2 Mg CaCO3 ha-1 (SAl1, un testigo (SAl2 y suelo adicionado de dos niveles de saturación Al (SAl1, SAl4 utilizando Trifolium repens como hospedero. Las plantas mostraron capacidad para asociarse con las especies inoculadas presentando mayor efectividad R-113-SAl1 sinergismo positivo expresado en variables microbiológicas como nodulación (16 nódulos maceta-1, esporas de hongos micorrícicos arbusculares, HMA (384 esporas 100g-1, colonización HMA (45% junto con variables agronómicas alcanzándose un incremento de biomasa foliar (93,5% frente al testigo. Niveles más elevados de Al afectaron la inoculación con cepas de colección; así, con R-109 se obtuvo el menor crecimiento radical y nodulación respecto al suelo natural mientras que R-113 fue la cepa más efectiva.Aluminium phytotoxicity is a serious limitation of the productivity of prairies growing on volcanic soil by affecting nodulation and effectiveness of Rhizobium. The aim of this study was to select Rhizobium strains to determine the effect as inoculant on Trifolium repens cropped in an Andisol with different aluminium saturation levels. Acidity tolerance (pH 4.5 and 6.0 of twelve Rhizobium strains of collection at three Al levels (100, 200, 300 µM was evaluated in mineral nutritive medium vitro. Simultaneously, in a greenhouse trial, strains effectivity were tested by inoculation of Trifolium pratense growing in an acidic Andisol and compared with dry matter accumulation produced by native strains. According to the results of this two trials, three Rhizobium strains (R-109, R-113 and R-115 were selected to study the effect of their inoculation on Trifolium repens growth cropped in an Andisol at four Al saturation levels (SAl1 to SAl4. In addition, the effect on arbuscular mycorrhizal propagules was also studied. Plants showed different capacity for association with the inoculated strains giving the best response R-113 at SAl1 level with positive synergism expressed by microbiological parameters such as high nodulation (16 nodules pot-1, AMF spore number (384 spores 100 g-1, root colonization percentage (45%, together with agronomical variables with an increase of aerial phytomass (93,5% in comparison with the control. Higher Al levels had an deleterious effect on the inoculation of collection strains; therefore, with R-109 strain inoculation the smallest root growth and nodulation were observed in comparison with soil with native strains whereas R-113 was the more effective one.

  13. Formatversionering. Et overblik

    Pia Majbritt Jensen

    2005-09-01

    Full Text Available Formatversionering spiller en stadig større rolle i den internationale tv- branche. Formater som “Big Brother” og “Vild med dans” findes på lokale tv-skærme i store dele af verden. En rapport fastslog for nylig, at formathandlen alene i Danmark i 2004 havde en anslået værdi på €60 mio., et tal der sandsynligvis er steget yderligere siden da (Sch- mitt et al. 2005. Artiklen gennemgår en række centrale aspekter ved de seneste års eksplosive formatudvikling. Først redegør artiklen for, hvad et tv-formater. Dernæst opridses, hvorfor formatversionering har fået en stadig stigende betydning internationalt. Hvilke fordele indeholder formatversionering sammenlignet med alternativerne, egenproduktion og indkøb af originale udenlandske programmer? Herefter argumente- res der for at se formaterne som del af en transnational mediekultur, i og med at de på den ene side er et resultat af den økonomiske, tekno- logiske og kulturelle globalisering, mens de på den anden side produce- res lokalt og foregår på lokale sprog, med lokale medvirkende. I for- længelse heraf gennemgås en konkret case – formatet “Ground Force” (på dansk “Hokus Krokus” – der illustrerer, hvor forskelligt to lokale versioneringer af det samme format kan tage sig ud. Til slut gives et overblik over de centrale positioner inden for den sparsomme forskning, der er udført på området, inden artiklen i en perspektiverende konklusion peger på vigtige aspekter ved fænomenet, en fremtidig forskning på om- rådet bør afdække.

  14. Final report of the project. Emission of nitrogen oxides by the soils. Measures, modelization, land registry and inventory. Impact on the air quality, the climatic change and the evaluation of possibilities of these emissions reduction; Rapport final du projet. Emissions d'oxydes d'azote par les sols. Mesures, modelisation, cadastre et inventaire. Impact sur la qualite de l'air, le changement climatique, et evaluation des gisements de reduction de ces emissions

    Serca, D.; Cortinovis, J. [LA Laboratoire d' Aerologie UMR 5560, 31 - Toulouse (France); Laville, P.; Gabrielle, B. [Institut National de Recherches Agronomiques (INRA), Environnement et Grandes Cultures, 78 - Thiverval-Grignon (France); Beekmann, M.; Ravetta, F. [Universite Pierre et Marie Curie, SA Service d' Aeronomie, 75 - Paris (France); Henault, C. [Institut National de Recherches Agronomiques (INRA-LMS) UMR Microbiologie des Sols-Geosol, 21 - Dijon (France)

    2007-07-01

    This project deals with NOx biosphere-atmosphere exchanges, NOx being considered as an indirect greenhouse gases (tropospheric O{sub 3} precursor). It relies on four laboratory specialized both on the soil-plant-atmosphere interface, and on the atmospheric chemistry. Methodology used bear on a set of in situ and laboratory measurements aiming at improving existing emission parameterization, or building new ones for the agro-ecosystems encountered in France or Europe. In situ measurements allowed to study the emission phenology in relation with relevant environmental parameters (meteorological, soil characteristics, and agricultural). Laboratory measurements allowed to establish an emission algorithm related to the three main parameters, that is, soil temperature, water and ammonia content. This algorithm has been adapted and simplified to spatialize the emissions at the France level. This spatialization was performed using environmental parameters accessible through data base (ECMWF) or agricultural statistics (such as nitrogen inputs, land use, crops). Spatial and temporal extrapolation allowed reaching the main objective, that is, to build a national inventory for a reference year (2002). This inventory allowed determining the contribution of NOx emitted by soil as compared to total emitted NOx, and the proportion of NOx emitted by soil due to fertilizer use. Our study, based on 57% of the French used agricultural area, and extrapolated to the whole arable surface, shows that soils would be responsible of about 5% of the total NOx emissions. On these 5%, 20%, which finally is a rather low percentage, would be linked to fertilizer use. The impact of these emissions on the atmospheric chemistry has been evaluated using the CHIMERE chemistry-transport model. We found that NOx emissions from soil would be of minor importance when compared to the industrial emissions, being a factor of ten lower in France. As a matter of consequence, the impact of the emissions on the maximum ozone concentration during summer months is relatively limited over Europe, but can reach 2 to 3 ppb for some of the rural French regions. (author)

  15. La balle et la plume

    Peter Marquis

    2012-06-01

    Full Text Available Fin octobre 2008, la nouvelle fit l’effet d’une bombe : Barack Obama, alors candidat à la présidence américaine, demanda à la chaîne câblée Fox News de retarder le début du sixième match de la World Series de base-ball afin de diffuser un spot de campagne. Son adversaire, John McCain, soutenu par le camp républicain et une partie de la population, monta aussitôt au créneau pour dénoncer l’hérésie : s’arroger le droit de perturber cette grande finale du championnat au déroulement immuable reve...

  16. La balle et la plume

    Peter Marquis

    2012-01-01

    Fin octobre 2008, la nouvelle fit l’effet d’une bombe : Barack Obama, alors candidat à la présidence américaine, demanda à la chaîne câblée Fox News de retarder le début du sixième match de la World Series de base-ball afin de diffuser un spot de campagne. Son adversaire, John McCain, soutenu par le camp républicain et une partie de la population, monta aussitôt au créneau pour dénoncer l’hérésie : s’arroger le droit de perturber cette grande finale du championnat au déroulement immuable reve...

  17. Drague et cruising

    Emmanuel Redoutey

    2008-04-01

    Full Text Available Dans la culture homosexuelle masculine, drague et cruising sont des termes équivalents. Ils désignent la quête d’un ou de plusieurs partenaires occasionnels et anonymes. Analyser leurs référents métaphoriques respectifs offre un éclairage particulier, à la fois phénoménologique et géographique, pour une compréhension nuancée des types de pratique et d’expérience qu’ils recouvrent. Cet article pose l’hypothèse d’une distinction entre deux figures, le dragueur et le cruiser, et postule que cette distinction se tient essentiellement dans l’opposition que Gilles Deleuze et Félix Guattari établissent entre ‘espace strié’ et ‘espace lisse’. L’essai de théorisation qui en découle est une manière de comprendre ce qui, entre sexualisation de l’espace et érotisation d’un mouvement exploratoire, fait fonctionner le script de la drague.In French gay culture, drague means cruising: looking for anonymous and 
casual sexual partners. This paper, by respectively examining the 
metaphorical underpinnings of both words, French and English, throws 
doubt on the validity of this translation. Through a phenomenological 
and geographical perspective, it attempts to give a nuanced examination 
of the practice and experience that each word conceals. The aim is to 
identify two figures embodied in a same person: the dragueur and the 
cruiser. I will argue that the distinction mainly rests on the 
opposition that Gilles Deleuze and Felix Guattari establish between ‘striated space’ and ‘smooth space’. The concluding theorical 
discussion is an attempt to understand what, in the tension between sexualization of space and eroticization of movement, guides the scripts of drague and cruising.

  18. Enfants, chercheurs et citoyens

    Lederman, Leon

    1998-01-01

    J'ai consacré ma vie à la physique. J'aimerais que tous les enfants aient la chance de satisfaire leur goût pour la recherche et de développer leur intelligence. J'ai découvert à Chicago, chez mon ami Leon Lederman, une méthode d'enseignement des sciences à l'école qui m'a subjugué. J'ai vu, à tous les niveaux, en physique, en chimie, en sciences naturelles et en mathématiques, des enfants qui expérimentaient avec joie, apprenaient les concepts fondamentaux à leur rythme, réfléchissant et discutant. Je voyais en gestation des êtres libres, capables de rechercher une vérité qui ne leur était pas assenée. J'ai voulu confronter des enseignants français du primaire et du secondaire à ces recherches qui ne se limitent pas à l'enseignement primaire. C'est leur regard critique et surtout leurs idées pour notre enseignement que j'ai rassemblés dans ce livre.

  19. Aspects Technologiques et Developpementaspects Technologiques et Developpement

    Sebedio Jean-Louis; Bretillon Lionel; Chardigny Jean-Michel

    2001-01-01

    L’acide linoléique conjugué (CLA) est présent dans les aliments d’origine animale, en particulier ceux issus des ruminants. Le CLA peut aussi être synthétisé au laboratoire par isomérisation alcaline de l’acide linoléique. Alors que l’isomère naturel est le 18 : 2 9c,11t, les produits de synthèse contiennent principalement deux isomères, les 18 : 2 9c,11t et 10t,12c. De nombreuses études menées sur des modèles animaux, le plus souvent avec des mélanges synthétiques, montrent des effets potent...

  20. Littérature et bande dessinée. Enjeux et limites

    Jan Baetens

    2009-05-01

    Full Text Available Le présent article se propose d’examiner deux aspects majeurs de la rencontre entre littérature et bande dessinée, dont le champ ne peut être limité à celui des seules adaptations de textes littéraires en bande dessinée. D’une part, il propose une définition de la bande dessinée littéraire (ou du roman graphique, peu importe la terminologie qui met l’accent sur le concept de récit, plus particulièrement sur le concept de récit visuel, pour analyser ensuite quels types de récits visuels sont considérés comme littéraires en bande dessinée. D’autre part, il démontre que l’analyse littéraire de la bande dessinée peut aider considérablement à renouveler l’étude de certains aspects de la théorie narrative, notamment dans le domaine du discours autobiographique et des techniques du feuilleton.This article deals with two crucial aspects of the encounter between literature and comics, which cannot be reduced to the mere problem of the adaptation of literary texts in comics. On the one hand, it offers a new definition of the literary comics (or graphic novel, although this kind of terminological discussions will be avoided here, which puts a strong emphasis on the concept of storytelling, more precisely of visual storytelling, and it analyzes which types of storytelling may be considered literary in the comics field. On the other hand, it argues that the literary reading of comics may prove dramatically helpful in the elaboration of new ways of interpreting narrative theory, for instance in the domain of autobiography as well as in the domain of the instalment techniques.

  1. Characterization of a symbiotically effective Rhizobium resistant to arsenic: Isolated from the root nodules of Vigna mungo (L.) Hepper grown in an arsenic-contaminated field.

    Mandal, Santi M; Pati, Bikas R; Das, Amit K; Ghosh, Ananta K

    2008-04-01

    Bacteria were isolated from the root nodules of Vigna mungo (L.) Hepper, grown in an arsenic-contaminated field and the strain was selected by its nodulation ability as well as better arsenic tolerant capacity compared to others. The selected strain was identified as Rhizobium by 16S rDNA sequencing and designated as VMA301. Phylogenetic analysis of the gene sequences showed its close relatedness with Sinorhizobium fredii. LC(50) value of arsenate for the bacteria as determined by flow cytometry was found to be 2.8 mM and arsenic uptake was measured by atomic absorption spectrometry as 0.048 mg g(-1) biomass. The high amount of arsenic was toxic to the cell, which changed the morphology of the bacteria to an elongated shape. Presence of a transcriptional regulatory gene (ArsR) of the ars genetic system was confirmed by amplification and sequencing. The symbiotic property of the isolate was also confirmed by amplification and sequencing of the NodC gene. These results indicate that the isolated Rhizobium bacteria may exert dual roles in the environment, arsenic bioremediation from the soil as well as increase of soil fertility through nitrogen fixation. PMID:18497483

  2. VsENOD5, VsENOD12 and VsENOD40 expression during Rhizobium-induced nodule formation on Vicia sativa roots

    Vijn, I; Yang, W C; Pallisgård, N; Jensen, E O; van Kammen, A; Bisseling, T

    1995-01-01

    We isolated ENOD5, ENOD12 and ENOD40 homologues from Vicia sativa and studied their expression pattern during Rhizobium-induced nodule formation. Comparison of the VsENOD40 nucleotide sequence with the pea, soybean and alfalfa ENOD40 sequences showed that the sequences contain two conserved regions...... expression pattern of VsENOD5, VsENOD12 and VsENOD40 during Rhizobium-induced nodule formation. Although the expression of these genes is largely similar to that of the pea counterparts, differences where found for the expression of VsENOD12 and VsENOD40 in Vicia. VsENOD12 is expressed in the whole...... prefixation zone II, whereas in pea ENOD12 is only expressed in the distal part of this zone. VsENOD40 is expressed in the uninfected cells of interzone II-III, while in pea ENOD40 is expressed in both the uninfected and infected cells of this zone. Udgivelsesdato: 1995-Sep...

  3. Identification of Rhizobium spp. in peat-based inoculants by DNA hybridization and PCR and its application in inoculant quality control.

    Tas, E; Saano, A; Leinonen, P; Lindström, K

    1995-05-01

    Procedures based on DNA hybridization and PCR were developed for quality control of Rhizobium inoculants. Inoculants for pea and goat's rue were produced by Elomestari Ltd., Juva, Finland, in sterile dry fine peat by the standard procedure used by the company. The inoculants contained Rhizobium galegae HAMBI 1174 and HAMBI 1207 and an R. leguminosarum biovar vicia strain, 16HSA, either solely or in combinations of two or three strains. DNA was isolated from 1-g samples of each peat inoculant and analyzed by nonradioactive DNA-DNA hybridization and by PCR. The hybridization probes were total DNAs from pure cultures of R. galegae HAMBI 1207 and R. leguminosarum biovar viciae 16HSA and a 264-bp strain-specific fragment from the genome of R. galegae HAMBI 1174. The total DNA probes distinguished inoculants containing R. galegae or R. leguminosarum, and the strain-specific probe distinguished inoculants containing R. galegae HAMBI 1174. The hybridization results for R. galegae were verified in a PCR experiment by amplifying an R. galegae species-specific fragment and an R. galegae HAMBI 1174 strain-specific fragment in the same reaction. When suitable probes and primers are available, the methods described here offer promising alternatives for the quality control of peat-based inoculants. PMID:7646020

  4. Strigolactones in the Rhizobium-legume symbiosis: Stimulatory effect on bacterial surface motility and down-regulation of their levels in nodulated plants.

    Peláez-Vico, María A; Bernabéu-Roda, Lydia; Kohlen, Wouter; Soto, María J; López-Ráez, Juan A

    2016-04-01

    Strigolactones (SLs) are multifunctional molecules acting as modulators of plant responses under nutrient deficient conditions. One of the roles of SLs is to promote beneficial association with arbuscular mycorrhizal (AM) fungi belowground under such stress conditions, mainly phosphorus shortage. Recently, a role of SLs in the Rhizobium-legume symbiosis has been also described. While SLs' function in AM symbiosis is well established, their role in the Rhizobium-legume interaction is still emerging. Recently, SLs have been suggested to stimulate surface motility of rhizobia, opening the possibility that they could also act as molecular cues. The possible effect of SLs in the motility in the alfalfa symbiont Sinorhizobium meliloti was investigated, showing that the synthetic SL analogue GR24 stimulates swarming motility in S. meliloti in a dose-dependent manner. On the other hand, it is known that SL production is regulated by nutrient deficient conditions and by AM symbiosis. Using the model alfalfa-S. meliloti, the impact of phosphorus and nitrogen deficiency, as well as of nodulation on SL production was also assessed. The results showed that phosphorus starvation promoted SL biosynthesis, which was abolished by nitrogen deficiency. In addition, a negative effect of nodulation on SL levels was detected, suggesting a conserved mechanism of SL regulation upon symbiosis establishment. PMID:26940496

  5. Effect of aldicarb on growth and radio-carbon (14C) and radio-phosphorus (32P) assimilation by Rhizobium japonicum

    In vitro studies on the effect of aldicarb (2-methyl-2-(methyl thio) propionaldehde-o-methyl carbamoyl oxime), a soil applied systemic insecticide, on Rhizobium japonicum revealed that the chemical (at 1,2 and 5 ppm levels) stimulated the growth of the organism initially upto 48 hr which declined thereafter upto 72 hr. The incorporation of 14C-glucose by the cells considerably reduced due to the insecticide treatment. The production of extracellular, water-soluble slime (polysacchardes) was also reduced considerably with increased concentrations of the chemical. However, the incorporation of 14C-radio-activity in the extracellular slime generally enhanced due to the treatment, upto 6 hr after injection of the radioactivity, which declined significantly later at 15 hr, indicating a qualitative difference in the extracellular polysaccharides produced by the insecticide treated cells. The insecticide treatment drastically reduced the incorporation of 32P-disodium hydrogen phosphate into Rhizobium cells, but enhanced the specific activity of the extracellular polysacchrides. (author)

  6. PERANAN FUNGI MIKORIZA ARBUSKULA, MIKROORGANISME PELARUT FOSFAT, RHIZOBIUM SP DAN ASAM HUMIK UNTUK MENINGKATKAN PERTUMBUHAN DAN PRODUKTIVITAS LEGUM Calopogonium mucunoides PADA TANAH LATOSOL DAN TAILING TAMBANG EMAS DI PT. ANEKA TAMBANG

    - Karti

    2014-06-01

    Full Text Available Latosols soil conditions are poor in nutrients and tailing of gold mine contain heavy metal causes low productivity of forage. The objective of this research to study the best combination of soil potential microorganisms and soil conditioner that can promote the growth and production of legume crops Calopogonium mucunoides Desv. Seven treatments used were A: control, B: arbuscular mycorrhizal fungi (AMF, C: AMF + Rhizobium, D: AMF + Phosphate Solubilizing Bacteria (BPF, E: AMF + Humic Acid, F: AMF + BPF + Rhizobium, G: AMF + BPF + Humic Acid + Rhizobium. Variables measured were the root dry weight, shoot dry weight, spread length, number of trifoliate leaves, the number of active root nodules, the percentage of root infection. Augmentation of soil microorganisms and soil conditioner not effective enough to improve plant growth of Calopogonium mucunoides Desv because plants can still adapt and grow well on latosols. Plants grown on tailings provide the best response is G (AMF+ Humic Acid + Rhizobium, although the rate of growth is not as good as plants grown in latosols.

  7. Diaspora grecque et francophonie aux XXe et XXIe siècles

    Efstratia Oktapoda-Lu

    2012-09-01

    Full Text Available Consacré aux auteurs grecs en exil, l’article d’Efstratia Oktapoda-Lu analyse un corpus d’œuvres publiées en français, où se déclinent différentes façons d’aborder la mémoire et la construction identitaire de l’individu, entre oubli et nostalgie, entre conflit et équilibre, entre retour fantasmé et expérience de la double culture.

  8. Qualité et action publique

    Marc Mormont

    2011-09-01

    Full Text Available L'article examine les conséquences pour l'action publique de la généralisation des procédures de qualité. Dans une première partie, la qualité est analysée historiquement comme un processus par lequel l'incertitude est réduite, essentiellement à l'intérieur du monde industriel, par des négociations entre entrepreneurs. La croissance de l'Etat social fait ensuite apparaître toutes les normes de qualité standard qui se réfèrent à des biens publics mais dont la production est largement déléguée à des experts et des négociations sectorielles sur un mode néo-corporatiste. Ceci élargit et confirme le modèle de la délégation de la qualité qui est conforme au schéma durkheimien de la production des normes.Trois évolutions récentes sont analysées. La première est l’entrée de la qualité dans le débat public qui élargit l’espace de demandes sociales de qualité à de nouveaux acteurs, plus diversifiés. La seconde est le rôle accru de la demande dans la définition de la qualité qui induit le secteur privé à articuler la qualité au consommateur. Enfin la qualité se définit de plus en plus de manière procédurale. Ces trois évolutions accentuent la tension entre l’espace de formulation des exigences de qualité et l’espace de la définition technique de la qualité. Ces trois évolutions valent mutatis mutandis pour le secteur public et posent de manière critique le rôle de l’Etat. Pour dépasser cette tension entre espace de la formulation des exigences de qualité et espace de normalisation technique, l’action publique doit être capable de prendre simultanément en charge débat et expertise dans un processus qui relève plus de l'innovation que de seule normalisation. Unmodèle expérimentaliste de l'action publique est proposé pour répondre à ce défi.

  9. Monge et le parmesan

    Mattatia, Fabrice

    2009-01-01

    Le lecteur curieux qui ouvre les Annales de Chimie, ou recueil de mémoires concernant la chimie et les arts qui en dépendent, par les citoyens Guyton, Monge, Berthollet, Fourcroy, Adet, Hassenfratz, Séguin, Vauquelin, C.A. Prieur, Chaptal et Van Mons, 30 vendémiaire an VIII sera peut-être surpris d’y trouver une Notice sur la fabrication du fromage de Lodézan, connu sous le nom de Parmézan, par Gaspard Monge. Cette notice de huit pages prouve que Monge profita également de son séjour en Itali...

  10. Hvad karakteriserer et talent?

    Raalskov, Jesper

    Debatten i medierne har i stigende grad fokus på talentfulde medarbejdere - men hvad er talent egentlig? I den akademiske litteratur inden for Talent Management (TM) gives der mange forskellige bud på, hvordan man som virksomhed kan udvikle og lede talenter, men færre af feltets inputgivere...... forholder sig til, hvad den overordnede definition af talent er. Der ses i litteraturen divergerende opfattelser af, hvilke konkrete egenskaber (attributter) som definerer et talent. I denne artikel gives et bud på en konsensusskabende tilgang til talent, idet talent kan ses som; det du har gjort (fortid...

  11. Lipochimie et innovations

    Alfos Carine

    2003-09-01

    Full Text Available Peut-on parler d’un nouvel âge d’or pour les produits à base de ressources végétales renouvelables et notamment pour les huiles ? Porteurs de performances spécifiques et de caractéristiques plus écologiquement correctes, leur emploi ouvre à l’industrie un potentiel d’innovations auquel participe le département de chimie et rhéologie de l’Iterg. La prise de conscience collective, associée aux évolutions des réglementations françaises et européennes, devrait conduire les industries à prendre de plus en plus en compte le respect de l’environnement dans leurs activités. La substitution de dérivés pétrochimiques par des produits d’origine agricole dans certains secteurs industriels (détergence, lubrifiants, solvants notamment contribue à la protection de notre environnement : diminution des volumes de déchets et des effluents, lutte contre l’effet de serre, moindre écotoxicité, innocuité pour la santé. De plus, l’épuisement latent des ressources pétrolières et la pratique de la jachère ont permis d’accélérer le développement de nouvelles voies de valorisations des huiles végétales et plus largement des agroressources. Les enjeux, à l’horizon 2010, sont bien plus importants encore pour ces produits, qui de part leur fonctionnalité spécifique, ont vocation à continuer d’occuper des marchés de niche. D’ici 10 ans, 2 à 3 millions d’hectares pourraient être consacrés à l’industrie du végétal \\; il s’agit là d’une véritable stratégie de développement durable qui nécessite un soutien politique, une vision à long terme et une motivation forte de l’industrie.

  12. Plastemballage i et recirkuleringsperspektiv

    Smith, Morten; Højfeldt Lund, Alexander Nicolas Jesper; Jensen, Bergliot Jeanne; Bertelsen, Kristine Dose

    2008-01-01

    Resume Nærværende opgave tager sit udgangspunkt William McDonough og Michael Braungarts Cradle to Cradle principperne. Cradle to Cradle er et nyt miljøparadigme på fremmarch med den centrale pointe at affald skal være lig føde. I opgaven fokuseres på Cradle to Cradles principper om recirkulering. Opgavens formål er at sætte disse generelle antagelser fra Cradle to Cradle ind i et virkelighedsperspektiv. Dette gøres ved hjælp af en case. Casen omhandler plastemballagefabrikanten Færch Plast...

  13. Aspects Technologiques et Developpementaspects Technologiques et Developpement

    Sebedio Jean-Louis

    2001-07-01

    Full Text Available L’acide linoléique conjugué (CLA est présent dans les aliments d’origine animale, en particulier ceux issus des ruminants. Le CLA peut aussi être synthétisé au laboratoire par isomérisation alcaline de l’acide linoléique. Alors que l’isomère naturel est le 18 : 2 9c,11t, les produits de synthèse contiennent principalement deux isomères, les 18 : 2 9c,11t et 10t,12c. De nombreuses études menées sur des modèles animaux, le plus souvent avec des mélanges synthétiques, montrent des effets potentiellement bénéfiques pour la santé (anticarcinogènes, protecteurs vis-à-vis de l’athérosclérose, modulateurs de la composition corporelle… alors que la plupart des études menées chez l’homme concernent les effets des CLA sur la composition corporelle. À ce jour, les données concernant les effets sur la composition corporelle chez l’homme semblent indiquer un bénéfice potentiel, mais les résultats restent controversés. Par ailleurs, bien qu’un effet anticarcinogène soit démontré chez l’animal, aucune étude chez l’homme n’a pu établir de relation entre CLA et cancer du sein. De plus, peu d’études traitant des aspects sécuritaires liés à la consommation à long terme ont été publiées. Par conséquent, il est nécessaire de disposer de plus de données en particulier chez l’Homme pour garantir l’innocuité de ces acides gras afin de protéger le consommateur, avant d’envisager l’utilisation de CLA dans des aliments fonctionnels.

  14. Ledelse i et interventionsperspektiv

    Keiding, Tina Bering

    Autopoetiske systemer er på det operative niveau lukkede for hinanden, hvilket betyder, at omverdenen eller andre systemer ikke kan gribe ind i et givent systems autopoiesis. Ledelse kan således ikke direkte specificere, det vil sige styre og kontrollere, de ledelsesudsatte systemers autopoiesis,...

  15. Raymond Williams - et overblik

    Michael Skovmand

    1990-01-01

    Raymond Williams er en af efterkrigstidens første kulturkritikere til at sætte den moderne massekommunikation og udvikling indenfor kom- munikationsteknologien ind i en større historisk og kulturel forståelses- ramme uden af forfalde til kulturpessimisme. I denne artikel giver Michael Skovmand et overblik over udviklingen i Williams kulturkritiske forfatterskab med en fyldig oversigt over de bøger, som er udgivet om ham efter hans død.

  16. Kun et skelet tilbage

    Dalsgaard, Anne Line

    Artiklen tager udgangspunkt i forfatterens nære kendskab til den unge kvinde, Evinha, som bor i et lavindkomst område i storbyen Recife i Nordøst Brasilien. Samtidig beskriver artiklen den ydmygelse, fattige borgere i Brasilien udsættes for, når deres familiemedlemmers knogler hældes i bendepotet...

  17. Décompositions arborescentes et problèmes de routage

    Li, Bi

    2014-01-01

    Dans cette thèse, nous étudions les décompositions arborescentes qui satisfont certaines contraintes supplémentaires et nous proposons des algorithmes pour les calculer dans certaines classes de graphes. Finalement, nous résolvons des problèmes liés au routage en utilisant ces décompositions ainsi que des propriétés structurelles des graphes. Cette thèse est divisée en deux parties. Dans la première partie, nous étudions les décompositions arborescentes satisfaisant des propriétés spécifiques...

  18. Entre exotisme et nostalgie

    Caroline Rozenholc

    2008-03-01

    Full Text Available En 1992, la municipalité de Tel-Aviv Jaffa, sollicitée par un groupe d’habitants, décide d’investir dans le quartier de Florentin. Florentin est alors un des quartiers les plus pauvres de la ville et témoigne, comme l’ensemble de la zone administrative sud, d’un état de forte dégradation. En quelques décennies, le quartier aura en effet été littéralement déserté par sa population, laissant vacants des centaines de logements progressivement investis par de petites industries. Le potentiel du quartier est pourtant évident – architecture unique et forte densité commerciale – et les réhabilitations réussies des quartiers de Neve Tseddek et de Sheinkin encouragent les autorités à « remettre Florentin sur la carte ». Cinq ans plus tard, Eytan Fox – plus connu aujourd’hui pour son film « The Bubble » – prend le quartier comme toile de fond pour réaliser une chronique de la jeunesse israélienne : « Florentin ». Pendant trois ans, cette série télévisée va obtenir une audience nationale confirmée par une rediffusion récente. Florentin est alors consacré comme un espace « à part » et devient emblématique d’une urbanité alternative. Paré d’une aura d’exotisme, renforcée par la présence de nombreux migrants africains, Florentin devient ainsi le lieu d’une certaine culture israélienne : celle d’une génération ouverte à l’altérité et qui, tout en étant ancrée dans la réalité du pays, se projette au-delà de ses frontières. Mêlant sens et temporalités, une conjoncture particulière fait donc émerger Florentin comme un label ; vivre à Florentin devient une véritable « déclaration d’intention ».En transition vers une gentrification évidente, comment ce quartier, longtemps marginalisée et qui n’est inclus dans les limites administratives de Tel-Aviv que depuis les années 50, en est venu à former une entité à part entière au sein de l’agglomération et à promouvoir l’identité globalisée de la ville ? Pour répondre à cette question, et pour contribuer à celle plus vaste de l’attachement au lieu dans la mondialisation, Florentin sert d’ancrage à une réflexion sur le quartier qui permet d’alimenter, entretiens et observations à l’appui, le débat entre tenants de l’hyper-mobilité et des nons-lieux et ceux d’une territorialité au fondement de la géographie et de l’urbanité. Florentin, espace complexe et stimulant, et dont on peut multiplier les « entrées », semble alors indiquer une troisième voie ; celle d’un lieu défini et ouvert où s’articulent, sans s’effacer, des temporalités et des perceptions du lieu distincts et propres, même si parfois partagées, à chacun.Florentin between exoticism and nostalgia.Globalization of an 'authentic' neighborhoodAt the beginning of the 90s, the Municipality of Tel-Aviv, approached by a small group of inhabitants of Florentin neighborhood, decides to invest in it. Florentin, at the time, is one of the poorest areas of the city and alike the whole South of Tel-Aviv, it is in an advanced state of deterioration. Over the last twenty years, buildings had fallen apart and all the population who had opportunities to leave the neighborhood found better dwellings. At the time, the potential of the neighborhood is nevertheless clear to the authorities – due to its peculiar architecture and the interesting mixture of residential and commercial activities – and the successful rehabilitations of both Neve Tseddek (the first Jewish neighborhood out the walls of the ancient Jaffa and Sheinkin street (today a very hype place to hang out stimulate the Municipality to “put Florentin back on the map”. This is a radical step as for few decades Florentin remained very much at the margins of the city, in between Tel-Aviv and Jaffa, only loosing population and gaining in polluting activities, such as small industries and manufactures. After few years of drastic investments, and due to an economical crisis, all initiatives remain pending. In 1997, the Israeli film director Eytan Fox – today known for his movie “The Bubble” depicting the in-a-bubble-like life in Tel-Aviv, detached from the ongoing conflict in the region – innovates by producing on the first commercial channel of Israel a serial depicting the Israeli youth: “Florentin”. This chronicle obtains, over three years, a national audience turning Florentin into the most known neighborhood of the country. Florentin is pictured as the space of an alternative urbanity. And it does become, exotic and different, the emblem of a certain way of life, of a certain Israeli young culture. The culture of a youth that is both very much anchored and connected to its place, to the country, but is simultaneously setting itself free and projecting itself over the national borders, all the way to New York or Goa, Soho, Lower East Side and so on.Produced by a circulation of meaning, “Florentin” turns into a label and happens to become more than a place. Florentin becomes a statement.How then, as a multiple entries space, marginalized and more recently gentrified, Florentin became to be considered a distinct entity among the globalized agglomeration of Tel-Aviv? To answer this question, and wishing to contribute to the ongoing debate between globalization as hyper-mobility, networks and non-places and globalization as inducing a new territoriality, even if still considered a condition sine qua non of geography and life in the city, and place as significant and defined, loaded with specific atmospheres. Florentin, a complex space made of many layers of history and meaning, shows a third path and demonstrates to be a defined but open place, where different temporalities and scales articulate more than they supplant one another. If this is true, it is also subject to changes as the place is changing fast and new gentrified population setting in the neighborhood are weighting much in the definition of the identity of the place. This moment is then, to the joy of the researcher, presenting the particularities of transitions in action.

  19. Primitivisme et surréalisme : une  « synthèse » impossible ?

    Philippe Sabot

    2004-04-01

    Full Text Available Cet article s’interroge sur le statut complexe de la figure du « primitif » au sein du surréalisme, et particulièrement au sein de l’œuvre d’André Breton. L’A. s’attache à montrer d’abord que le surréalisme s’inscrit clairement dans la lignée d’un certain nombre de mouvements culturels et artistiques se fondant sur une réévaluation critique des schémas mentaux et esthétiques imposés par le « rationalisme » occidental. Mais il cherche également à souligner l’ambiguïté constitutive du primitivisme surréaliste, en quête d’une primitivité à la fois lointaine et originaire, qui ferait coïncider l’homme primitif et le primitif en l’homme. Les différentes formes prises par le primitivisme surréaliste, notamment ses formes littéraires, témoignent alors de manière exemplaire de cette ambiguïté et de la synthèse impossible entre la théorie surréaliste du primitif et une pratique primitiviste.The article puts questions on the complex status of “the Primitive” within Surrealism, and particularly within some works of André Breton. The author at first aims at showing that Surrealism prolongs some cultural and artistic movements based on critics about the intellectual and esthetical ideals of the occidental rationalism. But he aims especially at showing the fundamental ambiguity of a surrealist primitivism, which searches a kind of “Primitivity” (both distant and original, as operating a coincidence between the primitive man and the primitive in man. The varied forms of the surrealist primitivism, particularly its literary forms, finally testifies that the synthesis between the surrealist theory of the Primitive and a primitivist practice is impossible.

  20. Expertise et validation.

    Christian Ruby

    2005-03-01

    Full Text Available La question des experts et de l’expertise n’est sans doute pas nouvelle 1 , mais elle peut prendre une ampleur différente selon les contextes et les finalités. Quoi qu’il en soit, on ne saurait séparer l’expert de la perspective d’une validation requise de ce qui est ou doit être considéré comme une œuvre, un acte, un concept ou un travail de « valeur ». Si la notion d’expert est largement « méliorante » dans certains contextes de référence, c’est que l’expert ...