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Sample records for alpha-proteobacterium sinorhizobium meliloti

  1. Identification of Sinorhizobium meliloti Genes Regulated during Symbiosis

    Science.gov (United States)

    Cabanes, Didier; Boistard, Pierre; Batut, Jacques

    2000-01-01

    RNA fingerprinting by arbitrarily primed PCR was used to isolate Sinorhizobium meliloti genes regulated during the symbiotic interaction with alfalfa (Medicago sativa). Sixteen partial cDNAs were isolated whose corresponding genes were differentially expressed between symbiotic and free-living conditions. Thirteen sequences corresponded to genes up-regulated during symbiosis, whereas three were instead repressed during establishment of the symbiotic interaction. Seven cDNAs corresponded to known or predicted nif and fix genes. Four presented high sequence similarity with genes not yet identified in S. meliloti, including genes encoding a component of the pyruvate dehydrogenase complex, a cell surface protein component, a copper transporter, and an argininosuccinate lyase. Finally, five cDNAs did not exhibit any similarity with sequences present in databases. A detailed expression analysis of the nine non-nif-fix genes provided evidence for an unexpected variety of regulatory patterns, most of which have not been described so far. PMID:10850975

  2. PCR Analysis of "expR" Gene Regulating Biosynthesis of Exopolysaccharides in "Sinorhizobium Meliloti"

    Science.gov (United States)

    Sorroche, Fernando G.; Giordano, Walter

    2012-01-01

    Exopolysaccharide (EPS) production by the rhizobacterium "Sinorhizobium meliloti" is essential for root nodule formation on its legume host (alfalfa), and for establishment of a nitrogen-fixing symbiosis between the two partners. Production of EPS II (galactoglucan) by certain "S. meliloti" strains results in a mucoid colony phenotype. Other…

  3. Biotin Limitation in Sinorhizobium meliloti Strain 1021 Alters Transcription and Translation

    OpenAIRE

    Heinz, Elke B.; Streit, Wolfgang R.

    2003-01-01

    Most Sinorhizobium meliloti strains lack several key genes involved in microbial biotin biosynthesis, and it is assumed that this may be a special adaptation which allows the microbe to down-regulate metabolic activities in the absence of a host plant. To further explore this hypothesis, we employed two different strategies. (i) Searches of the S. meliloti genome database in combination with the construction of nine different gusA reporter fusions identified three genes involved in a biotin s...

  4. Functional Analysis of Sinorhizobium meliloti Genes Involved in Biotin Synthesis and Transport

    OpenAIRE

    Entcheva, Plamena; Phillips, Donald A.; Streit, Wolfgang R.

    2002-01-01

    External biotin greatly stimulates bacterial growth and alfalfa root colonization by Sinorhizobium meliloti strain 1021. Several genes involved in responses to plant-derived biotin have been identified in this bacterium, but no genes required for biotin transport are known, and not all loci required for biotin synthesis have been assigned. Searches of the S. meliloti genome database in combination with complementation tests of Escherichia coli biotin auxotrophs indicate that biotin synthesis ...

  5. Analysis of Infection Thread Development Using Gfp- and DsRed-Expressing Sinorhizobium meliloti

    OpenAIRE

    Gage, Daniel J.

    2002-01-01

    Sinorhizobium meliloti growth inside infection threads was monitored after inoculation of alfalfa with red- or green-tagged bacteria. Most threads were populated with single bacterial types. Mixed infections were present but gave mixed nodules less often than expected. These patterns are explained by a model describing bacterial growth during infection.

  6. FeuN, a novel modulator of two-component signaling identified in Sinorhizobium meliloti

    OpenAIRE

    Carlyon, Rebecca E.; Ryther, Joanna L.; VanYperen, Ryan D.; Griffitts, Joel S.

    2010-01-01

    Sinorhizobium meliloti is a nitrogen-fixing bacterial symbiont of alfalfa and related legumes. Symbiotic infection by S. meliloti requires an osmosensory two-component system composed of the response regulator FeuP and the sensor kinase FeuQ. The FeuPQ pathway positively regulates transcription of multiple genes including ndvA, which encodes the cyclic glucan exporter. Here we show that proper regulation of this signaling pathway is essential for cell viability. Without the small 83 amino-aci...

  7. Sinorhizobium meliloti Cells Require Biotin and either Cobalt or Methionine for Growth

    OpenAIRE

    Watson, Robert J.; Heys, Roselyn; Martin, Teresa; Savard, Marc

    2001-01-01

    Sinorhizobium meliloti is usually cultured in rich media containing yeast extract. It has been suggested that some components of yeast extract are also required for growth in minimal medium. We tested 27 strains of this bacterium and found that none were able to grow in minimal medium when methods to limit carryover of yeast extract were used during inoculation. By fractionation of yeast extract, two required growth factors were identified. Biotin was found to be absolutely required for growt...

  8. Genetic analysis of signal integration by the Sinorhizobium meliloti sensor kinase FeuQ

    OpenAIRE

    VanYperen, Ryan D.; Orton, Taylor S.; Griffitts, Joel S.

    2015-01-01

    Two-component signalling systems allow bacteria to recognize and respond to diverse environmental stimuli. Auxiliary proteins can provide an additional layer of control to these systems. The Sinorhizobium meliloti FeuPQ two-component system is required for symbiotic development and is negatively regulated by the auxiliary small periplasmic protein FeuN. This study explores the mechanistic basis of this regulation. We provide evidence that FeuN directly interacts with the sensor kinase FeuQ. I...

  9. Sinorhizobium meliloti requires a cobalamin-dependent ribonucleotide reductase for symbiosis with its plant host

    OpenAIRE

    Taga, Michiko E.; Walker, Graham C.

    2010-01-01

    Vitamin B[subscript 12] (cobalamin) is a critical cofactor for animals and protists, yet its biosynthesis is limited to prokaryotes. We previously showed that the symbiotic nitrogen-fixing alphaproteobacterium Sinorhizobium meliloti requires cobalamin to establish a symbiotic relationship with its plant host, Medicago sativa (alfalfa). Here, the specific requirement for cobalamin in the S. meliloti–alfalfa symbiosis was investigated. Of the three known cobalamin-dependent enzymes in S. melilo...

  10. Biodegradable plastics from Sinorhizobium meliloti as plastics compatible with the environment and human health

    Directory of Open Access Journals (Sweden)

    Mehrdad Hashemi Beidokhti

    2016-03-01

    Full Text Available Introduction: Polyhydroxyalkanoates (PHAs are natural polyesters and biodegradable plastics that are stored as intracellular inclusion bodies by a great variety of bacteria. The aim of this study was to extract polyhydroxyalkanoate from native Sinorhizobium meliloti in Iran. Materials and methods: Sinorhizobium meliloti isolates were collected from roots of alfalfa plants and were identified by Gram staining, biochemical experiments and amplification of 1500 bp fragment of 16Sr DNA gene. PHA granules were detected by microscopic examination. PHA production was evaluated in nutrient deficient medium and its amount was determined by conversion of PHA into crotonic acid by sulphuric acid treatment. The effect of various temperatures, agitation rate and carbon source (sucrose, mannitol, and maltose were evaluated on dry cell weight and polyhydroxybutyrate (PHB production. Results: The maximum amount of polymer production (43.10% was seen in basal mineral medium at 29°C, pH~7 and 215 revolutions per minute (rpm. The results of this research showed that the S5 isolate was capable to produce maximum poly3- hydroxybutyrate. The produced polymer was analyzed for its purity by GC- mass (gas chromatography- mass spectroscopy and confirmed to be PHB compared with the standard polymer. Discussion and conclusion: Native strains of Sinorhizobium can be used in the production of biodegradable plastics and the results of present study showed that S. meliloti S5 was capable to produce maximum PHB at 29°C, agitation rate of 215 rpm, and pH~7. 

  11. Deficiency of a Sinorhizobium meliloti bacA Mutant in Alfalfa Symbiosis Correlates with Alteration of the Cell Envelope

    OpenAIRE

    Ferguson, Gail P.; Roop II, R. Martin; Walker, Graham C.

    2002-01-01

    The BacA protein is essential for the long-term survival of Sinorhizobium meliloti and Brucella abortus within acidic compartments in plant and animal cells, respectively. Since both the S. meliloti and B. abortus bacA mutants have an increased resistance to bleomycin, it was hypothesized that BacA was a transporter of bleomycin and bleomycin-like compounds into the bacterial cell. However, our finding that the S. meliloti bacA mutant also has an increased sensitivity to detergents, a hydroph...

  12. Exogenous Camp upregulates the expression of glnII and glnK-amtB genes in Sinorhizobium meliloti 1021

    Institute of Scientific and Technical Information of China (English)

    TIAN Zhexian; MAO Xianjun; SU Wei; LI Jian; BECKER Anke; WANG Yiping

    2006-01-01

    The existence of multiple adenylate cyclase encoding genes implies the importance of Camp in Sinorhizobium meliloti 1021. In this study, as a pioneer step of understanding Camp roles, microarray analysis on S. Meliloti was carried out for the function of exogenous Camp. To our surprise, the result showed that the transcriptions of glnII and glnK genes were significantly upshifted in the presence of exogenous Camp in S. Meliloti. This phenomenon is further confirmed in S. Meliloti that the expression of either glnII or glnK promoter-lacZ translational fusion is higher in the presence of exogenous Camp.Therefore, for the first time, we have identified genes from S. Meliloti whose expression is activated by Camp. The potential physiological role of upregulation of glnII and glnK by Camp is discussed.

  13. Cloning-free genome engineering in Sinorhizobium meliloti advances applications of Cre/loxP site-specific recombination.

    Science.gov (United States)

    Döhlemann, Johannes; Brennecke, Meike; Becker, Anke

    2016-09-10

    The soil-dwelling α-proteobacterium Sinorhizobium meliloti serves as model for studies of symbiotic nitrogen fixation, a highly important process in sustainable agriculture. Here, we report advancements of the genetic toolbox accelerating genome editing in S. meliloti. The hsdMSR operon encodes a type-I restriction-modification (R-M) system. Transformation of S. meliloti is counteracted by the restriction endonuclease HsdR degrading DNA which lacks the appropriate methylation pattern. We provide a stable S. meliloti hsdR deletion mutant showing enhanced transformation with Escherichia coli-derived plasmid DNA and demonstrate that using an E. coli plasmid donor, expressing S. meliloti methyl transferase genes, is an alternative strategy of increasing the transformation efficiency of S. meliloti. Furthermore, we devise a novel cloning-free genome editing (CFGE) method for S. meliloti, Agrobacterium tumefaciens and Xanthomonas campestris, and demonstrate the applicability of this method for intricate applications of the Cre/lox recombination system in S. meliloti. An enhanced Cre/lox system, allowing for serial deletions of large genomic regions, was established. An assay of lox spacer mutants identified a set of lox sites mediating specific recombination. The availability of several non-promiscuous Cre recognition sites enables simultaneous specific Cre/lox recombination events. CFGE combined with Cre/lox recombination is put forward as powerful approach for targeted genome editing, involving serial steps of manipulation to expedite the genetic accessibility of S. meliloti as chassis. PMID:27393468

  14. Absence of functional TolC protein causes increased stress response gene expression in Sinorhizobium meliloti

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    Moreira Leonilde M

    2010-06-01

    Full Text Available Abstract Background The TolC protein from Sinorhizobium meliloti has previously been demonstrated to be required for establishing successful biological nitrogen fixation symbiosis with Medicago sativa. It is also needed in protein and exopolysaccharide secretion and for protection against osmotic and oxidative stresses. Here, the transcriptional profile of free-living S. meliloti 1021 tolC mutant is described as a step toward understanding its role in the physiology of the cell. Results Comparison of tolC mutant and wild-type strains transcriptomes showed 1177 genes with significantly increased expression while 325 had significantly decreased expression levels. The genes with an increased expression suggest the activation of a cytoplasmic and extracytoplasmic stress responses possibly mediated by the sigma factor RpoH1 and protein homologues of the CpxRA two-component regulatory system of Enterobacteria, respectively. Stress conditions are probably caused by perturbation of the cell envelope. Consistent with gene expression data, biochemical analysis indicates that the tolC mutant suffers from oxidative stress. This is illustrated by the elevated enzyme activity levels detected for catalase, superoxide dismutase and glutathione reductase. The observed increase in the expression of genes encoding products involved in central metabolism and transporters for nutrient uptake suggests a higher metabolic rate of the tolC mutant. We also demonstrated increased swarming motility in the tolC mutant strain. Absence of functional TolC caused decreased expression mainly of genes encoding products involved in nitrogen metabolism and transport. Conclusion This work shows how a mutation in the outer membrane protein TolC, common to many bacterial transport systems, affects expression of a large number of genes that act in concert to restore cell homeostasis. This finding further underlines the fundamental role of this protein in Sinorhizobium meliloti biology.

  15. Complementation analyses of Sinorhizobium meliloti nifA mutant with different originated nifA genes

    Institute of Scientific and Technical Information of China (English)

    YAO Zhenhua; R(U)VERG Silvia; WANG Yiping; ZOU Huasong; TIAN Zhexian; DAI Xiaomi; BECKER Anke; LI Jian; YAN Haiqin; XIAO Yan; ZHU Jiabi; YU Guanqiao

    2006-01-01

    A previous work inferred that the nifA gene of Enterobacter cloacae did not restore the symbiotic phenotype of Sinorhizobium meliloti nifA mutant. In the present study, two nifA genes of Bradyrhizobium japonicum and Mesorhizobium huakuii also did not restore the symbiotic phenotype of S.meliloti nifA mutant. In whole genomic microarray experiments, 238 genes were found to be differentially expressed after S. meliloti nifA had been constitutively expressed in its nifA mutant. In contrast,only 20, 7 and 9 genes changed their transcriptional levels when expressing B. japonium, M. huakuii and Enterobacter cloacae nifA genes in Sm nifA mutant,separately. These genes were classified into several functional groups including house keeping, energy and central intermediary metabolism, transport systems and symbiosis. Interestingly, the genes that of nifH operons showed high expression levels in the presence of either B. japonium or M. huakuii NifA,which was confirmed by subsequent lacZ fusion experiments.

  16. Proline auxotrophy in Sinorhizobium meliloti results in a plant-specific symbiotic phenotype.

    Science.gov (United States)

    diCenzo, George C; Zamani, Maryam; Cowie, Alison; Finan, Turlough M

    2015-12-01

    In order to effectively manipulate rhizobium-legume symbioses for our benefit, it is crucial to first gain a complete understanding of the underlying genetics and metabolism. Studies with rhizobium auxotrophs have provided insight into the requirement for amino acid biosynthesis during the symbiosis; however, a paucity of available L-proline auxotrophs has limited our understanding of the role of L-proline biosynthesis. Here, we examined the symbiotic phenotypes of a recently described Sinorhizobium meliloti L-proline auxotroph. Proline auxotrophy was observed to result in a host-plant-specific phenotype. The S. meliloti auxotroph displayed reduced symbiotic capability with alfalfa (Medicago sativa) due to a decrease in nodule mass formed and therefore a reduction in nitrogen fixed per plant. However, the proline auxotroph formed nodules on white sweet clover (Melilotus alba) that failed to fix nitrogen. The rate of white sweet clover nodulation by the auxotroph was slightly delayed, but the final number of nodules per plant was not impacted. Examination of white sweet clover nodules by confocal microscopy and transmission electron microscopy revealed the presence of the S. meliloti proline auxotroph cells within the host legume cells, but few differentiated bacteroids were identified compared with the bacteroid-filled plant cells of WT nodules. Overall, these results indicated that L-proline biosynthesis is a general requirement for a fully effective nitrogen-fixing symbiosis, likely due to a transient requirement during bacteroid differentiation. PMID:26395514

  17. nifH Promoter Activity Is Regulated by DNA Supercoiling in Sinorhizobium meliloti

    Institute of Scientific and Technical Information of China (English)

    Yan-Jie LIU; Biao HU; Jia-Bi ZHU; Shan-Jiong SHEN; Guan-Qiao YU

    2005-01-01

    In prokaryotes, DNA supercoiling regulates the expression of many genes; for example, the expression of Klebsiella pneumoniae nifLA operon depends on DNA negative supercoiling in anaerobically grown cells, which indicates that DNA supercoiling might play a role in gene regulation of the anaerobic response. Since the expression of the nifH promoter in Sinorhizobium meliloti is not repressed by oxygen, it is proposed that the status of DNA supercoiling may not affect the expression of the nifH promoter. We tested this hypothesis by analyzing nifH promoter activity in wild-type and gyr- Escherichia coli in the presence and absence of DNA gyrase inhibitors. Our results show that gene expression driven by the S.meliloti nifH promoter requires the presence of active DNA gyrase. Because DNA gyrase increases the number of negative superhelical turns in DNA in the presence of ATP, our data indicate that negative supercoiling is also important for nifH promoter activity. Our study also shows that the DNA supercoilingdependent S. meliloti nifH promoter activity is related to the trans-acting factors NtrC and NifA that activate it. DNA supercoiling appeared to have a stronger effect on NtrC-activated nifH promoter activity than on NifA-activated promoter activity. Collectively, these results from the S. meliloti nifH promoter model system seem to indicate that, in addition to regulating gene expression during anaerobic signaling, DNA supercoiling may also provide a favorable topology for trans-acting factor binding and promoter activation regardless of oxygen status.

  18. The Sinorhizobium meliloti RNA chaperone Hfq influences central carbon metabolism and the symbiotic interaction with alfalfa

    Directory of Open Access Journals (Sweden)

    Jiménez-Zurdo José I

    2010-03-01

    Full Text Available Abstract Background The bacterial Hfq protein is able to interact with diverse RNA molecules, including regulatory small non-coding RNAs (sRNAs, and thus it is recognized as a global post-transcriptional regulator of gene expression. Loss of Hfq has an extensive impact in bacterial physiology which in several animal pathogens influences virulence. Sinorhizobium meliloti is a model soil bacterium known for its ability to establish a beneficial nitrogen-fixing intracellular symbiosis with alfalfa. Despite the predicted general involvement of Hfq in the establishment of successful bacteria-eukaryote interactions, its function in S. meliloti has remained unexplored. Results Two independent S. meliloti mutants, 2011-3.4 and 1021Δhfq, were obtained by disruption and deletion of the hfq gene in the wild-type strains 2011 and 1021, respectively, both exhibiting similar growth defects as free-living bacteria. Transcriptomic profiling of 1021Δhfq revealed a general down-regulation of genes of sugar transporters and some enzymes of the central carbon metabolism, whereas transcripts specifying the uptake and metabolism of nitrogen sources (mainly amino acids were more abundant than in the wild-type strain. Proteomic analysis of the 2011-3.4 mutant independently confirmed these observations. Symbiotic tests showed that lack of Hfq led to a delayed nodulation, severely compromised bacterial competitiveness on alfalfa roots and impaired normal plant growth. Furthermore, a large proportion of nodules (55%-64% elicited by the 1021Δhfq mutant were non-fixing, with scarce content in bacteroids and signs of premature senescence of endosymbiotic bacteria. RT-PCR experiments on RNA from bacteria grown under aerobic and microoxic conditions revealed that Hfq contributes to regulation of nifA and fixK1/K2, the genes controlling nitrogen fixation, although the Hfq-mediated regulation of fixK is only aerobiosis dependent. Finally, we found that some of the recently

  19. Three way interactions between Thymus vulgaris, Medicago truncatula and Sinorhizobium meliloti

    DEFF Research Database (Denmark)

    Grøndahl, Eva; Ehlers, Bodil Kirstine

    2012-01-01

    fitness than thyme experienced ones, irrespective of whether the soil was amended with thyme oil or not. Furthermore, there was a small, but significant difference in Medicago fitness between naive and experienced plant genotypes on soil amended with thyme oil. Thyme experienced Medicago genotypes......Thymus vulgaris is a dominating component of the Mediterranean garrigue vegetation. It produces aromatic oil, containing monoterpenes, which affects the performance (growth, survival) of other plants, and microorganisms. Annual plant species of the genus Medicago are commonly found in Mediterranean...... thyme communities; in fact they often grow very close to thyme plants (within 1 square meter). Medicago has a symbiosis with the nitrogen fixing bacteria Sinorhizobium meliloti – which is essential for nitrogen uptake in the nutrient poor garrigue. The aim of this study was to examine 1) if Medicago...

  20. Transcriptome analysis of Sinorhizobium meliloti nodule bacteria in nifA mutant background

    Institute of Scientific and Technical Information of China (English)

    TIAN Zhexian; WANG Yiping; ZOU Huasong; LI Jian; ZHANG Yuantao; LIU Ying; YU Guanqiao; ZHU Jiabi; R(U)BERG Silvia; BECKER Anke

    2006-01-01

    Gene expression profiles of a Sinorhizobium meliloti 1021 nifA mutant and wild type nodule bacteria were compared using whole genome microarrays. The results revealed a large scale alteration of gene expression (601 genes) in the nifA minus background. The loss of NifA altered the expression of many functional groups of genes (macromolecular metabolism, TCA cycle and respiration,nodulation and nitrogen fixation) and may lead to quite different life stages of the nodule bacteria.Upregulation of fixK and its associated genes was observed in the nifA mutant nodule bacteria. Additional quantitative real-time PCR experiments revealed that the transcript levels of fixLJ were significantly upshifted in the nifA mutant nodule bacteria.Putative NifA binding sites were predicted by a statistical method in the upstream sequences of 13 differentially regulated genes from the nifA- transcriptome.

  1. Crystallization and preliminary crystallographic studies of the recombinant dihydropyrimidinase from Sinorhizobium meliloti CECT4114

    International Nuclear Information System (INIS)

    The dihydropyrimidinase from S. meliloti CECT4114, with activity towards both hydantoin and dihydrouracil substrates, was crystallized, and diffraction data were collected to 1.85 Å resolution. Dihydropyrimidinases are involved in the reductive pathway of pyrimidine degradation, catalysing the hydrolysis of 5,6-dihydrouracil and 5,6-dihydrothymine to the corresponding N-carbamoyl β-amino acids. This enzyme has often been referred to as hydantoinase owing to its industrial application in the production of optically pure amino acids starting from racemic mixtures of 5-monosubstituted hydantoins. Recombinant dihydropyrimidinase from Sinorhizobium meliloti CECT4114 (SmelDhp) has been expressed, purified and crystallized. Crystallization was performed using the counter-diffusion method with capillaries of 0.3 mm inner diameter. Crystals of SmelDhp suitable for data collection and structure determination were grown in the presence of agarose at 0.1%(w/v) in order to ensure mass transport controlled by diffusion. X-ray data were collected to a resolution of 1.85 Å. The crystal belongs to the orthorhombic space group C2221, with unit-cell parameters a = 124.89, b = 126.28, c = 196.10 Å and two molecules in the asymmetric unit. A molecular-replacement solution has been determined and refinement is in progress

  2. Spatiotemporal choreography of chromosome and megaplasmids in the Sinorhizobium meliloti cell cycle.

    Science.gov (United States)

    Frage, Benjamin; Döhlemann, Johannes; Robledo, Marta; Lucena, Daniella; Sobetzko, Patrick; Graumann, Peter L; Becker, Anke

    2016-06-01

    A considerable share of bacterial species maintains multipartite genomes. Precise coordination of genome replication and segregation with cell growth and division is vital for proliferation of these bacteria. The α-proteobacterium Sinorhizobium meliloti possesses a tripartite genome composed of one chromosome and the megaplasmids pSymA and pSymB. Here, we investigated the spatiotemporal pattern of segregation of these S. meliloti replicons at single cell level. Duplication of chromosomal and megaplasmid origins of replication occurred spatially and temporally separated, and only once per cell cycle. Tracking of FROS (fluorescent repressor operator system)-labelled origins revealed a strict temporal order of segregation events commencing with the chromosome followed by pSymA and then by pSymB. The repA2B2C2 region derived from pSymA was sufficient to confer the spatiotemporal behaviour of this megaplasmid to a small plasmid. Altering activity of the ubiquitous prokaryotic replication initiator DnaA, either positively or negatively, resulted in an increase in replication initiation events or G1 arrest of the chromosome only. This suggests that interference with DnaA activity does not affect replication initiation control of the megaplasmids. PMID:26853523

  3. Metabolic modelling reveals the specialization of secondary replicons for niche adaptation in Sinorhizobium meliloti.

    Science.gov (United States)

    diCenzo, George C; Checcucci, Alice; Bazzicalupo, Marco; Mengoni, Alessio; Viti, Carlo; Dziewit, Lukasz; Finan, Turlough M; Galardini, Marco; Fondi, Marco

    2016-01-01

    The genome of about 10% of bacterial species is divided among two or more large chromosome-sized replicons. The contribution of each replicon to the microbial life cycle (for example, environmental adaptations and/or niche switching) remains unclear. Here we report a genome-scale metabolic model of the legume symbiont Sinorhizobium meliloti that is integrated with carbon utilization data for 1,500 genes with 192 carbon substrates. Growth of S. meliloti is modelled in three ecological niches (bulk soil, rhizosphere and nodule) with a focus on the role of each of its three replicons. We observe clear metabolic differences during growth in the tested ecological niches and an overall reprogramming following niche switching. In silico examination of the inferred fitness of gene deletion mutants suggests that secondary replicons evolved to fulfil a specialized function, particularly host-associated niche adaptation. Thus, genes on secondary replicons might potentially be manipulated to promote or suppress host interactions for biotechnological purposes. PMID:27447951

  4. Rhizobial galactoglucan determines the predatory pattern of Myxococcus xanthus and protects Sinorhizobium meliloti from predation

    Science.gov (United States)

    Pérez, Juana; Jiménez-Zurdo, José I.; Martínez-Abarca, Francisco; Millán, Vicenta; Shimkets, Lawrence J.; Muñoz-Dorado, José

    2014-01-01

    Summary Myxococcus xanthus is a social bacterium that preys on prokaryotic and eukaryotic microorganisms. Co-culture of M. xanthus with reference laboratory strains and field isolates of the legume symbiont Sinorhizobium meliloti revealed two different predatory patterns that resemble frontal and wolfpack attacks. Use of mutants impaired in the two types of M. xanthus surface motility (A or adventurous and S or social motility) and a csgA mutant, which is unable to form macroscopic travelling waves known as ripples, has demonstrated that both motility systems but not rippling are required for efficient predation. To avoid frontal attack and reduce killing rates, rhizobial cells require a functional expR gene. ExpR regulates expression of genes involved in a variety of functions. The use of S. meliloti mutants impaired in several of these functions revealed that the exopolysaccharide galactoglucan (EPS II) is the major determinant of the M. xanthus predatory pattern. The data also suggest that this biopolymer confers an ecological advantage to rhizobial survival in soil, which may have broad environmental implications. PMID:24707988

  5. The Symbiosis Interactome: a computational approach reveals novel components, functional interactions and modules in Sinorhizobium meliloti

    Directory of Open Access Journals (Sweden)

    Rodriguez-Llorente Ignacio

    2009-06-01

    Full Text Available Abstract Background Rhizobium-Legume symbiosis is an attractive biological process that has been studied for decades because of its importance in agriculture. However, this system has undergone extensive study and although many of the major factors underpinning the process have been discovered using traditional methods, much remains to be discovered. Results Here we present an analysis of the 'Symbiosis Interactome' using novel computational methods in order to address the complex dynamic interactions between proteins involved in the symbiosis of the model bacteria Sinorhizobium meliloti with its plant hosts. Our study constitutes the first large-scale analysis attempting to reconstruct this complex biological process, and to identify novel proteins involved in establishing symbiosis. We identified 263 novel proteins potentially associated with the Symbiosis Interactome. The topology of the Symbiosis Interactome was used to guide experimental techniques attempting to validate novel proteins involved in different stages of symbiosis. The contribution of a set of novel proteins was tested analyzing the symbiotic properties of several S. meliloti mutants. We found mutants with altered symbiotic phenotypes suggesting novel proteins that provide key complementary roles for symbiosis. Conclusion Our 'systems-based model' represents a novel framework for studying host-microbe interactions, provides a theoretical basis for further experimental validations, and can also be applied to the study of other complex processes such as diseases.

  6. Genetic and biochemical characterization of arginine biosynthesis in Sinorhizobium meliloti 1021.

    Science.gov (United States)

    Hernández, Victor M; Girard, Lourdes; Hernández-Lucas, Ismael; Vázquez, Alejandra; Ortíz-Ortíz, Catalina; Díaz, Rafael; Dunn, Michael F

    2015-08-01

    L-Ornithine production in the alfalfa microsymbiont Sinorhizobium meliloti occurs as an intermediate step in arginine biosynthesis. Ornithine is required for effective symbiosis but its synthesis in S. meliloti has been little studied. Unlike most bacteria, S. meliloti 1021 is annotated as encoding two enzymes producing ornithine: N-acetylornithine (NAO) deacetylase (ArgE) hydrolyses NAO to acetate and ornithine, and glutamate N-acetyltransferase (ArgJ) transacetylates l-glutamate with the acetyl group from NAO, forming ornithine and N-acetylglutamate (NAG). NAG is the substrate for the second step of arginine biosynthesis catalysed by NAG kinase (ArgB). Inactivation of argB in strain 1021 resulted in arginine auxotrophy. The activity of purified ArgB was significantly inhibited by arginine but not by ornithine. The purified ArgJ was highly active in NAO deacetylation/glutamate transacetylation and was significantly inhibited by ornithine but not by arginine. The purified ArgE protein (with a 6His-Sumo affinity tag) was also active in deacetylating NAO. argE and argJ single mutants, and an argEJ double mutant, are arginine prototrophs. Extracts of the double mutant contained aminoacylase (Ama) activity that deacetylated NAO to form ornithine. The purified products of three candidate ama genes (smc00682 (hipO1), smc02256 (hipO2) and smb21279) all possessed NAO deacetylase activity. hipO1 and hipO2, but not smb21279, expressed in trans functionally complemented an Escherichia coli ΔargE : : Km mutant. We conclude that Ama activity accounts for the arginine prototrophy of the argEJ mutant. Transcriptional assays of argB, argE and argJ, fused to a promoterless gusA gene, showed that their expression was not significantly affected by exogenous arginine or ornithine. PMID:26271664

  7. Systematic insertion mutagenesis of GntR family transcriptional regulator genes in Sinorhizobium meliloti

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    GntR-type transcriptional regulators regulate the most diverse biological processes in bacteria. Although GntR-type transcriptional regulators consist of the second largest family of transcriptional regulators in Sinorhizobium meliloti, little is known about their functions. In this study, we investigated 54 putative genes encoding GntR family of transcriptional regulators in S. meliloti Rm1021. Secondary structure analysis of the C-terminal domain of these putative transcriptional regulators indicated that thirty-seven were members of the FadR subfamily, ten of the HutC subfamily and five of the MocR subfamily. The remaining two did not fall into any specific subfamily category, and may form two new subfamilies. The 54 gntR genes were mutagenized by plasmid insertion mutagenesis to investigate their roles. We found that, of the 54 mutants, only the gtrA1 and gtrB1 mutants had slower growth rates and cell maximal yields on both rich medium and minimal medium, and lower cell motility on swarming plate than wild type Rm1021. All mutants, with the exception of gtrA1 and gtrB1, can establish effective symbioses with alfalfa. Plants inoculated with gtrA1 and gtrB1 mutants grew shorter than those inoculated with wild type, and formed relatively smaller, round and light pink nodules, which were mainly located on lateral roots. And there was an abnormal increase in the number of nodules induced by both mutants. These results suggested that the gtrA1 and gtrB1 mutants were symbiotically deficient. Our work presents a global overview of GntR-like transcriptional regulators involved in symbiosis in S.meliloti, and provides new insight into the functions of GntR-like transcriptional regulators.

  8. Genetic Organization of the Region Encoding Regulation, Biosynthesis, and Transport of Rhizobactin 1021, a Siderophore Produced by Sinorhizobium meliloti

    OpenAIRE

    Lynch, Damien; O'Brien, John; Welch, Timothy; Clarke, Paul; Ó Cuív, Páraic; Crosa, Jorge H.; O'Connell, Michael

    2001-01-01

    Eight genes have been identified that function in the regulation, biosynthesis, and transport of rhizobactin 1021, a hydroxamate siderophore produced under iron stress by Sinorhizobium meliloti. The genes were sequenced, and transposon insertion mutants were constructed for phenotypic analysis. Six of the genes, named rhbABCDEF, function in the biosynthesis of the siderophore and were shown to constitute an operon that is repressed under iron-replete conditions. Another gene in the cluster, n...

  9. The Type IV Secretion System of Sinorhizobium meliloti Strain 1021 Is Required for Conjugation but Not for Intracellular Symbiosis▿

    OpenAIRE

    Jones, Kathryn M.; Lloret, Javier; Daniele, Joseph R.; Walker, Graham C.

    2006-01-01

    The type IV secretion system (T4SS) of the plant intracellular symbiont Sinorhizobium meliloti 1021 is required for conjugal transfer of DNA. However, it is not required for host invasion and persistence, unlike the T4SSs of closely related mammalian intracellular pathogens. A comparison of the requirement for a bacterial T4SS in plant versus animal host invasion suggests an important difference in the intracellular niches occupied by these bacteria.

  10. Exploring the symbiotic pangenome of the nitrogen-fixing bacterium Sinorhizobium meliloti

    Energy Technology Data Exchange (ETDEWEB)

    Galardini, Marco [University of Florence; Mengoni, Alessio [University of Florence; Brilli, Matteo [Universite de Lyon, France; Pini, Francesco [University of Florence; Fioravanti, Antonella [University of Florence; Lucas, Susan [U.S. Department of Energy, Joint Genome Institute; Lapidus, Alla L. [U.S. Department of Energy, Joint Genome Institute; Cheng, Jan-Fang [U.S. Department of Energy, Joint Genome Institute; Goodwin, Lynne A. [Los Alamos National Laboratory (LANL); Pitluck, Sam [U.S. Department of Energy, Joint Genome Institute; Land, Miriam L [ORNL; Hauser, Loren John [ORNL; Woyke, Tanja [U.S. Department of Energy, Joint Genome Institute; Mikhailova, Natalia [U.S. Department of Energy, Joint Genome Institute; Ivanova, N [U.S. Department of Energy, Joint Genome Institute; Daligault, Hajnalka E. [Los Alamos National Laboratory (LANL); Bruce, David [Los Alamos National Laboratory (LANL); Detter, J. Chris [U.S. Department of Energy, Joint Genome Institute; Tapia, Roxanne [Los Alamos National Laboratory (LANL); Han, Cliff [Los Alamos National Laboratory (LANL); Teshima, Hazuki [Los Alamos National Laboratory (LANL); Mocali, Stefano [Agrobiol & Pedol Ctr ABP, Agr Res Council, I-50121 Florence, Italy; Bazzicalupo, Marco [University of Florence; Biondi, Emanuele [University of Florence

    2011-01-01

    Background: Sinorhizobium meliloti is a model system for the studies of symbiotic nitrogen fixation. An extensive polymorphism at the genetic and phenotypic level is present in natural populations of this species, especially in relation with symbiotic promotion of plant growth. AK83 and BL225C are two nodule-isolated strains with diverse symbiotic phenotypes; BL225C is more efficient in promoting growth of the Medicago sativa plants than strain AK83. In order to investigate the genetic determinants of the phenotypic diversification of S. meliloti strains AK83 and BL225C, we sequenced the complete genomes for these two strains. Results: With sizes of 7.14 Mbp and 6.97 Mbp, respectively, the genomes of AK83 and BL225C are larger than the laboratory strain Rm1021. The core genome of Rm1021, AK83, BL225C strains included 5124 orthologous groups, while the accessory genome was composed by 2700 orthologous groups. While Rm1021 and BL225C have only three replicons (Chromosome, pSymA and pSymB), AK83 has also two plasmids, 260 and 70 Kbp long. We found 65 interesting orthologous groups of genes that were present only in the accessory genome, consequently responsible for phenotypic diversity and putatively involved in plant-bacterium interaction. Notably, the symbiosis inefficient AK83 lacked several genes required for microaerophilic growth inside nodules, while several genes for accessory functions related to competition, plant invasion and bacteroid tropism were identified only in AK83 and BL225C strains. Presence and extent of polymorphism in regulons of transcription factors involved in symbiotic interaction were also analyzed. Our results indicate that regulons are flexible, with a large number of accessory genes, suggesting that regulons polymorphism could also be a key determinant in the variability of symbiotic performances among the analyzed strains.

  11. Contribution of Individual Chemoreceptors to Sinorhizobium meliloti Chemotaxis Towards Amino Acids of Host and Nonhost Seed Exudates.

    Science.gov (United States)

    Webb, Benjamin A; Helm, Richard F; Scharf, Birgit E

    2016-03-01

    Plant seeds and roots exude a spectrum of molecules into the soil that attract bacteria to the spermosphere and rhizosphere, respectively. The alfalfa symbiont Sinorhizobium meliloti utilizes eight chemoreceptors (McpT to McpZ and IcpA) to mediate chemotaxis. Using a modified hydrogel capillary chemotaxis assay that allows data quantification and larger throughput screening, we defined the role of S. meliloti chemoreceptors in sensing its host, Medicago sativa, and a closely related nonhost, Medicago arabica. S. meliloti wild type and most single-deletion strains displayed comparable chemotaxis responses to host or nonhost seed exudate. However, while the mcpZ mutant responded like wild type to M. sativa exudate, its reaction to M. arabica exudate was reduced by 80%. Even though the amino acid (AA) amounts released by both plant species were similar, synthetic AA mixtures that matched exudate profiles contributed differentially to the S. meliloti wild-type response to M. sativa (23%) and M. arabica (37%) exudates, with McpU identified as the most important chemoreceptor for AA. Our results show that S. meliloti is equally attracted to host and nonhost legumes; however, AA play a greater role in attraction to M. arabica than to M. sativa, with McpZ being specifically important in sensing M. arabica. PMID:26713349

  12. Role of extracellular compounds in Cd-sequestration relative to Cd uptake by bacterium Sinorhizobium meliloti

    Energy Technology Data Exchange (ETDEWEB)

    Slaveykova, Vera I., E-mail: vera.slaveykova@epfl.c [Environmental Biophysical Chemistry, IIE-ENAC, Ecole Polytechnique Federale de Lausanne (EPFL), Station 2, CH-1015 Lausanne (Switzerland); Parthasarathy, Nalini [Department of Inorganic, Analytic and Applied Chemistry, University of Geneva, Sciences II, 30 Quai Ernest Ansermet, 1211 Geneva 4 (Switzerland); Dedieu, Karine; Toescher, Denis [Environmental Biophysical Chemistry, IIE-ENAC, Ecole Polytechnique Federale de Lausanne (EPFL), Station 2, CH-1015 Lausanne (Switzerland)

    2010-08-15

    The role of bacterially derived compounds in Cd(II) complexation and uptake by bacterium Sinorhizobium meliloti wild type (WT) and genetically modified ExoY-mutant, deficient in exopolysaccharide production, was explored combining chemical speciation measurements and assays with living bacteria. Obtained results demonstrated that WT- and ExoY-strains excreted siderophores in comparable amounts, while WT-strain produced much higher amount of exopolysaccharides and less exoproteins. An evaluation of Cd(II) distribution in bacterial suspensions under short term exposure conditions, showed that most of the Cd is bound to bacterial surface envelope, including Cd bound to the cell wall and to the attached extracellular polymeric substances. However, the amount of Cd bound to the dissolved extracellular compounds increases at high Cd(II) concentrations. The implications of these findings to more general understanding of the Cd(II) fate and cycling in the environment is discussed. - Bacterial excreted extracellular compounds play minor role in Cd(II) sequestration relative to bacteria.

  13. Characteristics of the LrhA subfamily of transcriptional regulators from Sinorhizobium meliloti

    Institute of Scientific and Technical Information of China (English)

    Mingsheng Qi; Li Luo; Haiping Cheng; Jiabi Zhu; Guanqiao Yu

    2008-01-01

    In our previous work, we identified 94 putative genes encoding LysR-type transcriptional regulators from Sinorhizobium meliloti. All of these putative lysR genes were mutagenized using plasmid insertions to determine their phenotypes. Six LysR-type regulators, encoded by mutants SMa1979, SMb20715, SMc00820, SMc04163, SMc03975,and SMc04315, showed similar amino acid sequences (30%)and shared the conserved DNA-binding domain with LrhA,HexA, or DgdR. Phenotype analysis of these gene mutants indicated that the regulators control the swimming behaviors of the bacteria, production of quorum-sensing signals, and secretion of extracellular proteins. These characteristics are very similar to those of LrhA, HexA, and DgdR.Thus, we refer to this group as the LrhA subfamily. Sequence analysis showed that a great number of homologous genes of the LrhA subfamily were distributed in the α,β, and γsubdivisions of proteobacteria, and a few in actinobacteria. These findings could provide new clues to the roles of the LysR gene family.

  14. Effects of nutritional and environmental conditions on Sinorhizobium meliloti biofilm formation.

    Science.gov (United States)

    Rinaudi, Luciana; Fujishige, Nancy A; Hirsch, Ann M; Banchio, Erika; Zorreguieta, Angeles; Giordano, Walter

    2006-11-01

    Rhizobia are non-spore-forming soil bacteria that fix atmospheric nitrogen into ammonia in a symbiosis with legume roots. However, in the absence of a legume host, rhizobia manage to survive and hence must have evolved strategies to adapt to diverse environmental conditions. The capacity to respond to variations in nutrient availability enables the persistence of rhizobial species in soil, and consequently improves their ability to colonize and to survive in the host plant. Rhizobia, like many other soil bacteria, persist in nature most likely in sessile communities known as biofilms, which are most often composed of multiple microbial species. We have been employing in vitro assays to study environmental parameters that might influence biofilm formation in the Medicago symbiont Sinorhizobium meliloti. These parameters include carbon source, amount of nitrate, phosphate, calcium and magnesium as well as the effects of osmolarity and pH. The microtiter plate assay facilitates the detection of subtle differences in rhizobial biofilms in response to these parameters, thereby providing insight into how environmental stress or nutritional status influences rhizobial survival. Nutrients such as sucrose, phosphate and calcium enhance biofilm formation as their concentrations increase, whereas extreme temperatures and pH negatively affect biofilm formation. PMID:16887339

  15. Mining the Sinorhizobium meliloti transportome to develop FRET biosensors for sugars, dicarboxylates and cyclic polyols.

    Directory of Open Access Journals (Sweden)

    Alexandre Bourdès

    Full Text Available Förster resonance energy transfer (FRET biosensors are powerful tools to detect biologically important ligands in real time. Currently FRET bisosensors are available for twenty-two compounds distributed in eight classes of chemicals (two pentoses, two hexoses, two disaccharides, four amino acids, one nucleobase, two nucleotides, six ions and three phytoestrogens. To expand the number of available FRET biosensors we used the induction profile of the Sinorhizobium meliloti transportome to systematically screen for new FRET biosensors.Two new vectors were developed for cloning genes for solute-binding proteins (SBPs between those encoding FRET partner fluorescent proteins. In addition to a vector with the widely used cyan and yellow fluorescent protein FRET partners, we developed a vector using orange (mOrange2 and red fluorescent protein (mKate2 FRET partners. From the sixty-nine SBPs tested, seven gave a detectable FRET signal change on binding substrate, resulting in biosensors for D-quinic acid, myo-inositol, L-rhamnose, L-fucose, β-diglucosides (cellobiose and gentiobiose, D-galactose and C4-dicarboxylates (malate, succinate, oxaloacetate and fumarate. To our knowledge, we describe the first two FRET biosensor constructs based on SBPs from Tripartite ATP-independent periplasmic (TRAP transport systems.FRET based on orange (mOrange2 and red fluorescent protein (mKate2 partners allows the use of longer wavelength light, enabling deeper penetration of samples at lower energy and increased resolution with reduced back-ground auto-fluorescence. The FRET biosensors described in this paper for four new classes of compounds; (i cyclic polyols, (ii L-deoxy sugars, (iii β-linked disaccharides and (iv C4-dicarboxylates could be developed to study metabolism in vivo.

  16. Draft Genome Sequence of Sinorhizobium meliloti CCNWSX0020, a Nitrogen-Fixing Symbiont with Copper Tolerance Capability Isolated from Lead-Zinc Mine Tailings

    Science.gov (United States)

    Li, Zhefei; Ma, Zhanqiang; Hao, Xiuli

    2012-01-01

    Sinorhizobium meliloti CCNWSX0020 was isolated from Medicago lupulina plants growing in lead-zinc mine tailings, which can establish a symbiotic relationship with Medicago species. Also, the genome of this bacterium contains a number of protein-coding sequences related to metal tolerance. We anticipate that the genomic sequence provides valuable information to explore environmental bioremediation. PMID:22328762

  17. Effects of extraction methods on the composition and molar mass distributions of exopolymeric substances of the bacterium Sinorhizobium meliloti.

    Science.gov (United States)

    Alasonati, Enrica; Slaveykova, Vera I

    2012-06-01

    The influence of the extraction methods on the composition, size diversity, molar mass and size distributions of exopolymeric substances (EPS) from the bacterium Sinorhizobium meliloti wild type (WT) and by the exoY strain deficient in exopolysaccharide production was investigated. EPS obtained by centrifugation, EDTA and formaldehyde/NaOH were compared. It was found that the extraction method influenced TOC, TN and total protein content in EPS from both strains. However, no difference between EDTA and formaldehyde/NaOH methods was observed for the exopolysaccharide components. Similar functional groups and fluorescence pattern were found in the EPS obtained by different methods; however their relative abundance was method dependent. The extraction method also affected the molar mass and size distribution, HP SEC diversity among different treatment and bacterial strains. PMID:22507904

  18. Altered susceptibility to infection by Sinorhizobium meliloti and Nectria haematococca in alfalfa roots with altered cell cycle.

    Science.gov (United States)

    Woo, H-H; Hirsch, A M; Hawes, M C

    2004-07-01

    Most infections of plant roots are initiated in the region of elongation; the mechanism for this tissue-specific localization pattern is unknown. In alfalfa expressing PsUGT1 antisense mRNA under the control of the cauliflower mosaic virus (CaMV) 35S promoter, the cell cycle in roots is completed in 48 h instead of 24 h, and border cell number is decreased by more than 99%. These plants were found to exhibit increased root-tip infection by a fungal pathogen and reduced nodule formation by a bacterial symbiont. Thus, the frequency of infection in the region of elongation by Nectria haematocca was unaffected, but infection of the root tip was increased by more than 90%; early stages of Sinorhizobium meliloti infection and nodule morphology were normal, but the frequency of nodulation was fourfold lower than in wild-type roots. PMID:15042410

  19. Screening of Highly Effective Sinorhizobium meliloti Strains for 'Vector' Alfalfa and Testing of Its Competitive Nodulation Ability in the Field

    Institute of Scientific and Technical Information of China (English)

    ZENG Zhao-Hai; CHEN Wen-Xin; HU Yue-Gao; SUI Xin-Hua; CHEN Dan-Ming

    2007-01-01

    Seventeen Sinorhizobium meliloti strains from seven provinces in China were used to screen highly effective strains for alfalfa cultivar in a greenhouse study and their symbiotic relationship and competitive ability were studied in the field.CCBAU30138 was the most effective strain,as evidenced by increase in dry weights.A field experiment showed that the inoculation of alfalfa with CCBAU30138 resulted in increases of 11.9%and 19.6%of dry matter production and crude protein production,respectively,in forage of monocultured plants.The total dry matter yields of alfalfa and tall fescue in binary culture were increased by 16.3%by inoculation of alfalfa with this strain.These results showed that S.Meliloti strain CCBAU30138 was an effective inoculant both in the greenhouse and in the field.The analysis of randomly amplified polymorphic DNA(RAPD)by polymerase chain reaction(PCR)from nodule extracts showed that the strain CCBAU30138 had high competitiveness in the field.It occupied 47.5%of nodules in alfalfa monoculture and 44.4% of nodules in alfalfa-tall fescue binary culture after 20 weeks of growth.In conclusion,a simple system to select highly effective and competitive symbiotic strains specific to alfalfa was established.Using this system.A strain suitable for the alfalfa cultivar'Vector’grown in Wuqiao County of Hebei Province was obtained.

  20. Crystallization and preliminary crystallographic studies of an active-site mutant hydantoin racemase from Sinorhizobium meliloti CECT4114

    International Nuclear Information System (INIS)

    Crystals of an active-site mutated hydantoin racemase from S. meliloti have been obtained in the presence and absence of d,l-5-isopropyl-hydantoin and characterized by X-ray diffraction. A recombinant active-site mutant of hydantoin racemase (C76A) from Sinorhizobium meliloti CECT 4114 (SmeHyuA) has been crystallized in the presence and absence of the substrate d,l-5-isopropyl hydantoin. Crystals of the SmeHyuA mutant suitable for data collection and structure determination were grown using the counter-diffusion method. X-ray data were collected to resolutions of 2.17 and 1.85 Å for the free and bound enzymes, respectively. Both crystals belong to space group R3 and contain two molecules of SmeHyuA per asymmetric unit. The crystals of the free and complexed SmeHyuA have unit-cell parameters a = b = 85.43, c = 152.37 Å and a = b = 85.69, c = 154.38 Å, crystal volumes per protein weight (VM) of 1.94 and 1.98 Å3 Da−1 and solvent contents of 36.7 and 37.9%, respectively

  1. Sinorhizobium meliloti Controls Nitric Oxide-Mediated Post-Translational Modification of a Medicago truncatula Nodule Protein.

    Science.gov (United States)

    Blanquet, Pauline; Silva, Liliana; Catrice, Olivier; Bruand, Claude; Carvalho, Helena; Meilhoc, Eliane

    2015-12-01

    Nitric oxide (NO) is involved in various plant-microbe interactions. In the symbiosis between soil bacterium Sinorhizobium meliloti and model legume Medicago truncatula, NO is required for an optimal establishment of the interaction but is also a signal for nodule senescence. Little is known about the molecular mechanisms responsible for NO effects in the legume-rhizobium interaction. Here, we investigate the contribution of the bacterial NO response to the modulation of a plant protein post-translational modification in nitrogen-fixing nodules. We made use of different bacterial mutants to finely modulate NO levels inside M. truncatula root nodules and to examine the consequence on tyrosine nitration of the plant glutamine synthetase, a protein responsible for assimilation of the ammonia released by nitrogen fixation. Our results reveal that S. meliloti possesses several proteins that limit inactivation of plant enzyme activity via NO-mediated post-translational modifications. This is the first demonstration that rhizobia can impact the course of nitrogen fixation by modulating the activity of a plant protein. PMID:26422404

  2. [Growth and polysaccharide formation in Sinorhizobium meliloti strains in an air-lift-type fermentor. Effect on nodulation velocity in alfalfa plants].

    Science.gov (United States)

    Lorda, G S; Castaño, R C; Pordomingo, A B; Pastor, M D; Balatti, A P

    2003-01-01

    In this paper the influence of the exopolysaccharides produced by Sinorhizobium meliloti strains on the nodulation rates in alfalfa plants has been considered. The experiments were performed in a rotary shaker and in an air-lift type fermentor. Different Sinorhizobium meliloti strains were used. Bacterial growth rates were determined by viable cell counts. Exopolysaccharide concentration was determined by precipitation with ethanol. It was observed that maximum cell concentration was in the order of 1 x 10(10) cell/ml and exopolysaccharide content was approximately 11 g/l. The experiments performed with alfalfa plants in a controlled environment chamber showed that, when inoculation was carried out with diluted suspensions (1/10), nodulation time was reduced from 10 to 4 days, while the strains retained their symbiotic properties. PMID:12920984

  3. Temporal effects on the composition of a population of Sinorhizobium meliloti associated with Medicago sativa and Melilotus alba.

    Science.gov (United States)

    Bromfield, E S; Butler, G; Barran, L R

    2001-06-01

    An assessment was made of the impact of temporal separation on the composition of a population of Sinorhizobium meliloti associated with Medicago sativa (alfalfa) and Melilotus alba (sweet clover) grown at a single site that had no known history of alfalfa cultivation. Root nodules were sampled on six occasions over two seasons, and a total of 1620 isolates of S. meliloti were characterized on the basis of phage sensitivity using 16 typing phages. Plant infection tests indicated that symbiotic S. meliloti were deficient in the soil at the time of planting and that these bacteria were present at low density during the first season (soil); in the second season numbers increased markedly to about 10(5)/g of soil. Overall, 37 and 51 phage types, respectively, were encountered among the nodule isolates from M. sativa and M. alba. The data indicate significant temporal shifts in the frequency and diversity of types associated with the two legume species. Apparent temporal variation with respect to the frequency of types appeared largely unpredictable and was not attributable to any one sampling time. The results indicate an apparent reduction in phenotypic diversity over the course of the experiment. Differential host plant selection of specific types with respect to nodule occupancy was indicated by significant interactions between legume species and either the frequency or diversity of phage types. Isolates from M. sativa that were resistant to lysis by all typing phages (type 14) were unusual in that they were predominant on this host at all sampling times (between 53% and 82% nodule occupancy) and were relatively homogeneous on the basis of DNA hybridization with 98% of the isolates analysed sharing the same nod EFG hybridization profile. In contrast, those isolates from M. alba comprising type 14 were encountered at low total frequency (2%) and were genetically heterogeneous on the basis of Southern hybridization. The implications of the observed temporal and host

  4. oriT-Directed Cloning of Defined Large Regions from Bacterial Genomes: Identification of the Sinorhizobium meliloti pExo Megaplasmid Replicator Region

    OpenAIRE

    Patrick S G Chain; Hernandez-Lucas, Ismael; Golding, Brian; Finan, Turlough M.

    2000-01-01

    We have developed a procedure to directly clone large fragments from the genome of the soil bacterium Sinorhizobium meliloti. Specific regions to be cloned are first flanked by parallel copies of an origin of transfer (oriT) together with a plasmid replication origin capable of replicating large clones in Escherichia coli but not in the target organism. Supplying transfer genes in trans specifically transfers the oriT-flanked region, and in this process, site-specific recombination at the ori...

  5. Phylogenetic distribution and evolutionary pattern of an α-proteobacterial small RNA gene that controls polyhydroxybutyrate accumulation in Sinorhizobium meliloti.

    Science.gov (United States)

    Lagares, Antonio; Roux, Indra; Valverde, Claudio

    2016-06-01

    It has become clear that sRNAs play relevant regulatory functions in bacteria. However, a comprehensive understanding of their biological roles considering evolutionary aspects has not been achieved for most of them. Thus, we have characterized the evolutionary and phylogenetic aspects of the Sinorhizobium meliloti mmgR gene encoding the small RNA MmgR, which has been recently reported to be involved in the regulation of polyhydroxybutyrate accumulation in this bacterium. We constructed a covariance model from a multiple sequence and structure alignment of mmgR close homologs that allowed us to extend the search and to detect further remote homologs of the sRNA gene. From our results, mmgR seemed to evolve from a common ancestor of the α-proteobacteria that diverged from the order of Rickettsiales. We have found mmgR homologs in most current species of α-proteobacteria, with a few exceptions in which genomic reduction events or gene rearrangements seem to explain its absence. Furthermore, a strong microsyntenic relationship was found between a large set of mmgR homologs and homologs of a gene encoding a putative N-formyl glutamate amidohydrolase (NFGAH) that allowed us to trace back the evolutionary path of this group of mmgR orthologs. Among them, structure and sequence traits have been completely conserved throughout evolution, namely a Rho-independent terminator and a 10-mer (5'-UUUCCUCCCU-3') that is predicted to remain in a single-stranded region of the sRNA. We thus propose the definition of the new family of α-proteobacterial sRNAs αr8, as well as the subfamily αr8s1 which encompass S. meliloti mmgR orthologs physically linked with the downstream open reading frame encoding a putative NFGAH. So far, mmgR is the trans-encoded small RNA with the widest phylogenetic distribution of well recognized orthologs among α-proteobacteria. Expression of the expected MmgR transcript in rhizobiales other than S. meliloti (Sinorhizobium fredii, Rhizobium

  6. The induction of Sinorhizobium meliloti C4-dicarboxylate transport system(Dct)is regulated by oxygen concentration

    Institute of Scientific and Technical Information of China (English)

    WEN Jin; NAN Beiyan; Fergal O'Gara; WANG Yiping

    2005-01-01

    The Sinorhizobium meliloti C4-dicarboxylate transport (Dct) system is essential for symbiotic nitrogen fixation. The dctA gene, encoding the C4-dicarboxylate permease, is expressed in both free living and symbiotic cells. But in free living cells expression of dctD and dctB is absolutely required for the expression of dctA. In this study, in order to investigate the effect of oxygen concentration on the induction of Dct system, E. coli DH5α strain which carries the plasmid-encoded dctABD operon was used in tube assays. It was found that the specific induction of Dct system occurred only at a certain depth under the surface of M63- 0.6% agar media, suggesting that Dct system could respond to oxygen concentration during succinate-induced expression. Furthermore, when measured at different oxygen concentrations, the highest expression level was observed at oxygen concentration of 2%. Thus, we predict that in addition to dicarboxylates, the induction of Dct system may also regulated by oxygen concentration.

  7. Analysis of the downstream region of nodD3 P1 promoter by deletion and complementation tests in Sinorhizobium meliloti

    Institute of Scientific and Technical Information of China (English)

    陈迪; 刘彦杰; 朱家璧; 沈善炯; 俞冠翘

    2003-01-01

    In Sinorhizobium meliloti, the nodD3 gene is transcriptionally controlled by two promoters, P1 and P2. Under P1, there is a 660 bp sequence including a small open reading frame, ORF2, followed by the nodD3 coding region. Genetic analysis using the different deletions on the 3′ends of P1 downstream sequence showed that the downstream sequence +1-+125nt is essential for P1 expression. Complementation, mutations and nodulation tests demonstrated that the ORF2 auto-represses P1 expression, while the P1 downstream sequence +1-+125nt counteracts it.

  8. The stress-related, rhizobial small RNA RcsR1 destabilizes the autoinducer synthase encoding mRNA sinI in Sinorhizobium meliloti.

    Science.gov (United States)

    Baumgardt, Kathrin; Šmídová, Klára; Rahn, Helen; Lochnit, Günter; Robledo, Marta; Evguenieva-Hackenberg, Elena

    2016-05-01

    Quorum sensing is a cell density-dependent communication system of bacteria relying on autoinducer molecules. During the analysis of the post-transcriptional regulation of quorum sensing in the nitrogen fixing plant symbiont Sinorhizobium meliloti, we predicted and verified a direct interaction between the 5'-UTR of sinI mRNA encoding the autoinducer synthase and a small RNA (sRNA), which we named RcsR1. In vitro, RcsR1 prevented cleavage in the 5'-UTR of sinI by RNase E and impaired sinI translation. In line with low ribosomal occupancy and transcript destabilization upon binding of RcsR1 to sinI, overproduction of RcsR1 in S. meliloti resulted in lower level and shorter half-life of sinI mRNA, and in decreased autoinducer amount. Although RcsR1 can influence quorum sensing via sinI, its level did not vary at different cell densities, but decreased under salt stress and increased at low temperature. We found that RcsR1 and its stress-related expression pattern, but not the interaction with sinI homologs, are conserved in Sinorhizobium, Rhizobium and Agrobacterium. Consistently, overproduction of RcsR1 in S. meliloti and Agrobacterium tumefaciens inhibited growth at high salinity. We identified conserved targets of RcsR1 and showed that most conserved interactions and the effect on growth under salt stress are mediated by the first stem-loop of RcsR1, while its central part is responsible for the species-specific interaction with sinI. We conclude that RcsR1 is an ancient, stress-related riboregulator in rhizobia and propose that it links stress responses to quorum sensing in S. meliloti. PMID:26588798

  9. Nitrate reduction associated with respiration in Sinorhizobium meliloti 2011 is performed by a membrane-bound molybdoenzyme.

    Science.gov (United States)

    Ferroni, Felix M; Rivas, María G; Rizzi, Alberto C; Lucca, María E; Perotti, Nora I; Brondino, Carlos D

    2011-10-01

    The purification and biochemical characterization of the respiratory membrane-bound nitrate reductase from Sinorhizobium meliloti 2011 (Sm NR) is reported together with the optimal conditions for cell growth and enzyme production. The best biomass yield was obtained under aerobic conditions in a fed-batch system using Luria-Bertani medium with glucose as carbon source. The highest level of Sm NR production was achieved using microaerobic conditions with the medium supplemented with both nitrate and nitrite. Sm NR is a mononuclear Mo-protein belonging to the DMSO reductase family isolated as a heterodimeric enzyme containing two subunits of 118 and 45 kDa. Protein characterization by mass spectrometry showed homology with respiratory nitrate reductases. UV-Vis spectra of as-isolated and dithionite reduced Sm NR showed characteristic absorption bands of iron-sulfur and heme centers. Kinetic studies indicate that Sm NR follows a Michaelis-Menten mechanism (K (m) = 97 ± 11 μM, V = 9.4 ± 0.5 μM min(-1), and k (cat) = 12.1 ± 0.6 s(-1)) and is inhibited by azide, chlorate, and cyanide with mixed inhibition patterns. Physiological and kinetic studies indicate that molybdenum is essential for NR activity and that replacement of this metal for tungsten inhibits the enzyme. Although no narGHI gene cluster has been annotated in the genome of rhizobia, the biochemical characterization indicates that Sm NR is a Mo-containing NR enzyme with molecular organization similar to NarGHI. PMID:21432624

  10. The time course of the transcriptomic response of Sinorhizobium meliloti 1021 following a shift to acidic pH

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    Pühler Alfred

    2009-02-01

    Full Text Available Abstract Background The symbiotic soil bacterium Sinorhizobium meliloti often has to face low pH in its natural habitats. To identify genes responding to pH stress a global transcriptional analysis of S. meliloti strain 1021 following a pH shift from pH 7.0 to pH 5.75 was carried out. In detail, oligo-based whole genome microarrays were used in a time course experiment. The monitoring period covered a time span of about one hour after the pH shift. The obtained microarray data was filtered and grouped by K-means clustering in order to obtain groups of genes behaving similarly concerning their expression levels throughout the time course. Results The results display a versatile response of S. meliloti 1021 represented by distinct expression profiles of subsets of genes with functional relation. The eight generated clusters could be subdivided into a group of four clusters containing genes that were up-regulated and another group of four clusters containing genes that were down-regulated in response to the acidic pH shift. The respective mean expression progression of the four up-regulated clusters could be described as (i permanently and strong, (ii permanently and intermediate, (iii permanently and progressive, and (iv transiently up-regulated. The expression profile of the four down-regulated clusters could be characterized as (i permanently, (ii permanently and progressive, (iii transiently, and (iv ultra short down-regulated. Genes coding for proteins with functional relation were mostly cumulated in the same cluster, pointing to a characteristic expression profile for distinct cellular functions. Among the strongest up-regulated genes lpiA, degP1, cah, exoV and exoH were found. The most striking functional groups responding to the shift to acidic pH were genes of the exopolysaccharide I biosynthesis as well as flagellar and chemotaxis genes. While the genes of the exopolysaccharide I biosynthesis (exoY, exoQ, exoW, exoV, exoT, exoH, exoK exo

  11. Transcriptome profiling of a Sinorhizobium meliloti fadD mutant reveals the role of rhizobactin 1021 biosynthesis and regulation genes in the control of swarming

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    Olivares José

    2010-03-01

    Full Text Available Abstract Background Swarming is a multicellular phenomenom characterized by the coordinated and rapid movement of bacteria across semisolid surfaces. In Sinorhizobium meliloti this type of motility has been described in a fadD mutant. To gain insights into the mechanisms underlying the process of swarming in rhizobia, we compared the transcriptome of a S. meliloti fadD mutant grown under swarming inducing conditions (semisolid medium to those of cells grown under non-swarming conditions (broth and solid medium. Results More than a thousand genes were identified as differentially expressed in response to growth on agar surfaces including genes for several metabolic activities, iron uptake, chemotaxis, motility and stress-related genes. Under swarming-specific conditions, the most remarkable response was the up-regulation of iron-related genes. We demonstrate that the pSymA plasmid and specifically genes required for the biosynthesis of the siderophore rhizobactin 1021 are essential for swarming of a S. meliloti wild-type strain but not in a fadD mutant. Moreover, high iron conditions inhibit swarming of the wild-type strain but not in mutants lacking either the iron limitation response regulator RirA or FadD. Conclusions The present work represents the first transcriptomic study of rhizobium growth on surfaces including swarming inducing conditions. The results have revealed major changes in the physiology of S. meliloti cells grown on a surface relative to liquid cultures. Moreover, analysis of genes responding to swarming inducing conditions led to the demonstration that iron and genes involved in rhizobactin 1021 synthesis play a role in the surface motility shown by S. meliloti which can be circumvented in a fadD mutant. This work opens a way to the identification of new traits and regulatory networks involved in swarming by rhizobia.

  12. The tep1 gene of Sinorhizobium meliloti coding for a putative transmembrane efflux protein and N-acetyl glucosamine affect nod gene expression and nodulation of alfalfa plants

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    Soto María

    2009-01-01

    Full Text Available Abstract Background Soil bacteria collectively known as Rhizobium, characterized by their ability to establish beneficial symbiosis with legumes, share several common characteristics with pathogenic bacteria when infecting the host plant. Recently, it was demonstrated that a fadD mutant of Sinorhizobium meliloti is altered in the control of swarming, a type of co-ordinated movement previously associated with pathogenicity, and is also impaired in nodulation efficiency on alfalfa roots. In the phytopathogen Xanthomonas campestris, a fadD homolog (rpfB forms part of a cluster of genes involved in the regulation of pathogenicity factors. In this work, we have investigated the role in swarming and symbiosis of SMc02161, a S. meliloti fadD-linked gene. Results The SMc02161 locus in S. meliloti shows similarities with members of the Major Facilitator Superfamily (MFS of transporters. A S. meliloti null-mutant shows increased sensitivity to chloramphenicol. This indication led us to rename the locus tep1 for transmembrane efflux protein. The lack of tep1 does not affect the appearance of swarming motility. Interestingly, nodule formation efficiency on alfalfa plants is improved in the tep1 mutant during the first days of the interaction though nod gene expression is lower than in the wild type strain. Curiously, a nodC mutation or the addition of N-acetyl glucosamine to the wild type strain lead to similar reductions in nod gene expression as in the tep1 mutant. Moreover, aminosugar precursors of Nod factors inhibit nodulation. Conclusion tep1 putatively encodes a transmembrane protein which can confer chloramphenicol resistance in S. meliloti by expelling the antibiotic outside the bacteria. The improved nodulation of alfalfa but reduced nod gene expression observed in the tep1 mutant suggests that Tep1 transports compounds which influence nodulation. In contrast to Bradyrhizobium japonicum, we show that in S. meliloti there is no feedback regulation

  13. 'Ca. Liberibacter asiaticus' proteins orthologous with pSymA-encoded proteins of Sinorhizobium meliloti: hypothetical roles in plant host interaction.

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    L David Kuykendall

    Full Text Available Sinorhizobium meliloti strain 1021, a nitrogen-fixing, root-nodulating bacterial microsymbiont of alfalfa, has a 3.5 Mbp circular chromosome and two megaplasmids including 1.3 Mbp pSymA carrying nonessential 'accessory' genes for nitrogen fixation (nif, nodulation and host specificity (nod. A related bacterium, psyllid-vectored 'Ca. Liberibacter asiaticus,' is an obligate phytopathogen with a reduced genome that was previously analyzed for genes orthologous to genes on the S. meliloti circular chromosome. In general, proteins encoded by pSymA genes are more similar in sequence alignment to those encoded by S. meliloti chromosomal orthologs than to orthologous proteins encoded by genes carried on the 'Ca. Liberibacter asiaticus' genome. Only two 'Ca. Liberibacter asiaticus' proteins were identified as having orthologous proteins encoded on pSymA but not also encoded on the chromosome of S. meliloti. These two orthologous gene pairs encode a Na(+/K+ antiporter (shared with intracellular pathogens of the family Bartonellacea and a Co++, Zn++ and Cd++ cation efflux protein that is shared with the phytopathogen Agrobacterium. Another shared protein, a redox-regulated K+ efflux pump may regulate cytoplasmic pH and homeostasis. The pSymA and 'Ca. Liberibacter asiaticus' orthologs of the latter protein are more highly similar in amino acid alignment compared with the alignment of the pSymA-encoded protein with its S. meliloti chromosomal homolog. About 182 pSymA encoded proteins have sequence similarity (≤ E-10 with 'Ca. Liberibacter asiaticus' proteins, often present as multiple orthologs of single 'Ca. Liberibacter asiaticus' proteins. These proteins are involved with amino acid uptake, cell surface structure, chaperonins, electron transport, export of bioactive molecules, cellular homeostasis, regulation of gene expression, signal transduction and synthesis of amino acids and metabolic cofactors. The presence of multiple orthologs defies mutational

  14. A consolidated analysis of the physiologic and molecular responses induced under acid stress in the legume-symbiont model-soil bacterium Sinorhizobium meliloti.

    Science.gov (United States)

    Draghi, W O; Del Papa, M F; Hellweg, C; Watt, S A; Watt, T F; Barsch, A; Lozano, M J; Lagares, A; Salas, M E; López, J L; Albicoro, F J; Nilsson, J F; Torres Tejerizo, G A; Luna, M F; Pistorio, M; Boiardi, J L; Pühler, A; Weidner, S; Niehaus, K; Lagares, A

    2016-01-01

    Abiotic stresses in general and extracellular acidity in particular disturb and limit nitrogen-fixing symbioses between rhizobia and their host legumes. Except for valuable molecular-biological studies on different rhizobia, no consolidated models have been formulated to describe the central physiologic changes that occur in acid-stressed bacteria. We present here an integrated analysis entailing the main cultural, metabolic, and molecular responses of the model bacterium Sinorhizobium meliloti growing under controlled acid stress in a chemostat. A stepwise extracellular acidification of the culture medium had indicated that S. meliloti stopped growing at ca. pH 6.0-6.1. Under such stress the rhizobia increased the O2 consumption per cell by more than 5-fold. This phenotype, together with an increase in the transcripts for several membrane cytochromes, entails a higher aerobic-respiration rate in the acid-stressed rhizobia. Multivariate analysis of global metabolome data served to unequivocally correlate specific-metabolite profiles with the extracellular pH, showing that at low pH the pentose-phosphate pathway exhibited increases in several transcripts, enzymes, and metabolites. Further analyses should be focused on the time course of the observed changes, its associated intracellular signaling, and on the comparison with the changes that operate during the sub lethal acid-adaptive response (ATR) in rhizobia. PMID:27404346

  15. Sinorhizobium meliloti sigma factors RpoE1 and RpoE4 are activated in stationary phase in response to sulfite.

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    Bénédicte Bastiat

    Full Text Available Rhizobia are soil bacteria able to establish a nitrogen-fixing symbiosis with legume plants. Both in soil and in planta, rhizobia spend non-growing periods resembling the stationary phase of in vitro-cultured bacteria. The primary objective of this work was to better characterize gene regulation in this biologically relevant growth stage in Sinorhizobium meliloti. By a tap-tag/mass spectrometry approach, we identified five sigma factors co-purifying with the RNA polymerase in stationary phase: the general stress response regulator RpoE2, the heat shock sigma factor RpoH2, and three extra-cytoplasmic function sigma factors (RpoE1, RpoE3 and RpoE4 belonging to the poorly characterized ECF26 subgroup. We then showed that RpoE1 and RpoE4 i are activated upon metabolism of sulfite-generating compounds (thiosulfate and taurine, ii display overlapping regulatory activities, iii govern a dedicated sulfite response by controlling expression of the sulfite dehydrogenase SorT, iv are activated in stationary phase, likely as a result of endogenous sulfite generation during bacterial growth. We showed that SorT is required for optimal growth of S. meliloti in the presence of sulfite, suggesting that the response governed by RpoE1 and RpoE4 may be advantageous for bacteria in stationary phase either by providing a sulfite detoxification function or by contributing to energy production through sulfite respiration. This paper therefore reports the first characterization of ECF26 sigma factors, the first description of sigma factors involved in control of sulphur metabolism, and the first indication that endogenous sulfite may act as a signal for regulation of gene expression upon entry of bacteria in stationary phase.

  16. Comparative toxicity assessment of CeO{sub 2} and ZnO nanoparticles towards Sinorhizobium meliloti, a symbiotic alfalfa associated bacterium: Use of advanced microscopic and spectroscopic techniques

    Energy Technology Data Exchange (ETDEWEB)

    Bandyopadhyay, Susmita [Environmental Science and Engineering PhD Program, The University of Texas at El Paso, 500 West University Avenue, El Paso, TX 79968 (United States); University of California Center for Environmental Implications of Nanotechnology (UC CEIN), The University of Texas at El Paso (United States); Peralta-Videa, Jose R. [Department of Chemistry, The University of Texas at El Paso, 500 West University Avenue, El Paso, TX 79968 (United States); Plascencia-Villa, German; Jose-Yacaman, Miguel [Department of Physics and Astronomy, The University of Texas at San Antonio, One UTSA Circle, San Antonio, TX 78249 (United States); Gardea-Torresdey, Jorge L., E-mail: jgardea@utep.edu [Environmental Science and Engineering PhD Program, The University of Texas at El Paso, 500 West University Avenue, El Paso, TX 79968 (United States); Department of Chemistry, The University of Texas at El Paso, 500 West University Avenue, El Paso, TX 79968 (United States); University of California Center for Environmental Implications of Nanotechnology (UC CEIN), The University of Texas at El Paso (United States)

    2012-11-30

    Highlights: Black-Right-Pointing-Pointer First cytotoxicity study of CeO{sub 2} and ZnO nanoparticles to Sinorhizobium meliloti. Black-Right-Pointing-Pointer First report upon the mechanisms of CeO{sub 2} and ZnO NPs toxicity to S. meliloti. Black-Right-Pointing-Pointer ZnO NPs were found to be bactericidal in lower concentration. Black-Right-Pointing-Pointer CeO{sub 2} NPs had bacteriostatic effect on S. meliloti. - Abstract: Cerium oxide (CeO{sub 2}) and zinc oxide (ZnO) nanoparticles (NPs) are extensively used in a variety of instruments and consumer goods. These NPs are of great concern because of potential toxicity towards human health and the environment. The present work aimed to assess the toxic effects of 10 nm CeO{sub 2} and ZnO NPs towards the nitrogen fixing bacterium Sinorhizobium meliloti. Toxicological parameters evaluated included UV/Vis measurement of minimum inhibitory concentration, disk diffusion tests, and dynamic growth. Ultra high-resolution scanning transmission electron microscopy (STEM) and infrared spectroscopy (FTIR) were utilized to determine the spatial distribution of NPs and macromolecule changes in bacterial cells, respectively. Results indicate that ZnO NPs were more toxic than CeO{sub 2} NPs in terms of inhibition of dynamic growth and viable cells counts. STEM images revealed that CeO{sub 2} and ZnO NPs were found on bacterial cell surfaces and ZnO NPs were internalized into the periplasmic space of the cells. FTIR spectra showed changes in protein and polysaccharide structures of extra cellular polymeric substances present in bacterial cell walls treated with both NPs. The growth data showed that CeO{sub 2} NPs have a bacteriostatic effect, whereas ZnO NPs is bactericidal to S. meliloti. Overall, ZnO NPs were found to be more toxic than CeO{sub 2} NPs.

  17. Characterization of a novel acyl carrier protein, RkpF, encoded by an operon involved in capsular polysaccharide biosynthesis in Sinorhizobium meliloti

    International Nuclear Information System (INIS)

    Rhizobial capsular polysaccharides (RKPs) play an important role in the development of a nitrogen-fixing symbiosis with the plant host and in Sinorhizobium meliloti AK631 functional rkpABCDEF genes are required for the production of RKPs. After cloning the rkpF gene, we overexpressed and purified the derived protein product (RkpF) in Escherichia coli. Like acyl carrier protein (ACP), the RkpF protein can be labeled in vivo with radioactive beta-alanine added to the growth medium. If homogeneous RkpF protein is incubated with radiolabeled coenzyme A in the presence of purified holo-ACP synthase from E. coli, an in vitro transfer of 4'-phosphopantetheine to the RkpF protein can be observed. The conversion from apo-RkpF protein to holo-RkpF protein seems to go along with a major conformational change of the protein structure, because the holo-RkpF protein runs significantly faster on native polyacrylamide gel electrophoresis than the apo-RkpF protein. Electrospray mass spectrometric analysis reveals a mass of 9,585 for the apo-RkpF protein and a mass of 9,927 for the holo-RkpF protein. Our data show that RkpF is a novel ACP

  18. Predator/prey interaction between Pfiesteria piscicida and Rhodomonas mediated by a marine alpha proteobacterium.

    Science.gov (United States)

    Alavi, M R

    2004-01-01

    The dinoflagellate Pfiesteria piscicida coexists with bacteria in aquatic environments and as such, may interact with them at the physiological level. This study was designed to investigate the influence of bacteria, present in a clonal culture of Pfiesteria piscicida, on the predator/prey relationship of this dinoflagellate with the alga Rhodomonas. A series of replenishment experiments with bacteria isolated from P. piscicida clonal culture and the bacteria-free P. piscicida derived from the same culture were carried out. In the presence of bacteria, the number of P. piscicida increased significantly when incubated with alga Rhodomonas. This enhanced growth was almost entirely due to the increased consumption rate of Rhodomonas by P. piscicida since in bacteria-free (axenic) cultures Rhodomonas were consumed at significantly reduced rates relative to cultures with bacteria. Subsequent replenishment experiments with individual bacterial isolates showed that a single isolate was responsible for the increased predation rate of P. piscicida. The presence or absence of this specific bacterium determined the outcome of the interaction between P. piscicida and Rhodomonas. Partial sequence analysis of the 16S rDNA of this isolate indicated that it was a novel marine alpha proteobacterium with sequence similarities to a Roseobacter sp. and a bacterium recently isolated from a toxic dinoflagellate Alexandrium sp. PMID:15259269

  19. Genome analysis of DNA repair genes in the alpha proteobacterium Caulobacter crescentus

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    Menck Carlos FM

    2007-03-01

    Full Text Available Abstract Background The integrity of DNA molecules is fundamental for maintaining life. The DNA repair proteins protect organisms against genetic damage, by removal of DNA lesions or helping to tolerate them. DNA repair genes are best known from the gamma-proteobacterium Escherichia coli, which is the most understood bacterial model. However, genome sequencing raises questions regarding uniformity and ubiquity of these DNA repair genes and pathways, reinforcing the need for identifying genes and proteins, which may respond to DNA damage in other bacteria. Results In this study, we employed a bioinformatic approach, to analyse and describe the open reading frames potentially related to DNA repair from the genome of the alpha-proteobacterium Caulobacter crescentus. This was performed by comparison with known DNA repair related genes found in public databases. As expected, although C. crescentus and E. coli bacteria belong to separate phylogenetic groups, many of their DNA repair genes are very similar. However, some important DNA repair genes are absent in the C. crescentus genome and other interesting functionally related gene duplications are present, which do not occur in E. coli. These include DNA ligases, exonuclease III (xthA, endonuclease III (nth, O6-methylguanine-DNA methyltransferase (ada gene, photolyase-like genes, and uracil-DNA-glycosylases. On the other hand, the genes imuA and imuB, which are involved in DNA damage induced mutagenesis, have recently been described in C. crescentus, but are absent in E. coli. Particularly interesting are the potential atypical phylogeny of one of the photolyase genes in alpha-proteobacteria, indicating an origin by horizontal transfer, and the duplication of the Ada orthologs, which have diverse structural configurations, including one that is still unique for C. crescentus. Conclusion The absence and the presence of certain genes are discussed and predictions are made considering the particular

  20. La simbiosis fijadora de nitrógeno Sinorhizobium meliloti-alfalfa: aproximaciones ómicas aplicadas a la identificación y caracterización de determinantes genéticos del rizobio asociados a la colonización temprana de la raíz de alfalfa (Medicago sativa)

    OpenAIRE

    Salas, María Eugenia

    2015-01-01

    Sinorhizobium meliloti es una α-proteobacteria capaz de establecer asociaciones simbióticas con plantas de los géneros Medicago, Melilotus y Trigonella. Esta asociación es el resultado de un complejo diálogo molecular entre los simbiontes, que se diferencian a lo largo de la interacción para dar lugar a un nuevo órgano en las raíces de las plantas, el nódulo fijador de nitrógeno. El nicho simbiótico accesible a los rizobios está naturalmente limitado, y resulta ocupado por aquellas cepas que ...

  1. Essential Role for the BacA Protein in the Uptake of a Truncated Eukaryotic Peptide in Sinorhizobium meliloti▿

    OpenAIRE

    Marlow, Victoria L.; Haag, Andreas F.; Kobayashi, Hajime; Fletcher, Vivien; Scocchi, Marco; Walker, Graham C.; Ferguson, Gail P.

    2008-01-01

    The inner membrane BacA protein is essential for the establishment of chronic intracellular infections by Sinorhizobium meliloti and Brucella abortus within plant and mammalian hosts, respectively. In their free-living state, S. meliloti and B. abortus mutants lacking BacA have reductions in their outer membrane lipid A very-long-chain fatty acid (VLCFA) contents and exhibit low-level resistance to the glycopeptide bleomycin in comparison to their respective parent strains. In this paper we i...

  2. Denitrification by Rhizobium meliloti

    Energy Technology Data Exchange (ETDEWEB)

    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

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

    OpenAIRE

    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...

  4. Mixed Nodule Infection in Sinorhizobium meliloti–Medicago sativa Symbiosis Suggest the Presence of Cheating Behavior

    Science.gov (United States)

    Checcucci, Alice; Azzarello, Elisa; Bazzicalupo, Marco; Galardini, Marco; Lagomarsino, Alessandra; Mancuso, Stefano; Marti, Lucia; Marzano, Maria C.; Mocali, Stefano; Squartini, Andrea; Zanardo, Marina; Mengoni, Alessio

    2016-01-01

    In the symbiosis between rhizobia and legumes, host plants can form symbiotic root nodules with multiple rhizobial strains, potentially showing different symbiotic performances in nitrogen fixation. Here, we investigated the presence of mixed nodules, containing rhizobia with different degrees of mutualisms, and evaluate their relative fitness in the Sinorhizobium meliloti–Medicago sativa model symbiosis. We used three S. meliloti strains, the mutualist strains Rm1021 and BL225C and the non-mutualist AK83. We performed competition experiments involving both in vitro and in vivo symbiotic assays with M. sativa host plants. We show the occurrence of a high number (from 27 to 100%) of mixed nodules with no negative effect on both nitrogen fixation and plant growth. The estimation of the relative fitness as non-mutualist/mutualist ratios in single nodules shows that in some nodules the non-mutualist strain efficiently colonized root nodules along with the mutualist ones. In conclusion, we can support the hypothesis that in S. meliloti–M. sativa symbiosis mixed nodules are formed and allow non-mutualist or less-mutualist bacterial partners to be less or not sanctioned by the host plant, hence allowing a potential form of cheating behavior to be present in the nitrogen fixing symbiosis. PMID:27379128

  5. Compatibility of a wild type and its genetically modified Sinorhizobium strain with two mycorrhizal fungi on Medicago species as affected by drought stress.

    Science.gov (United States)

    Vázquez, M M.; Azcón, R; Barea, J M.

    2001-07-01

    The effect of double inoculation with two strains of Sinorhizobium meliloti [the wild type (WT) strain GR4 and its genetically modified (GM) derivative GR4(pCK3)], and two species of arbuscular mycorrhizal (AM) fungi (Glomus deserticola and Glomus intraradices) was examined in a microcosm system on three species of Medicago (M. nolana, M. rigidula, M. rotata). Two water regimes (80 and 100% water holding capacity, WHC) were assayed. The efficiency of each AM fungus increasing plant growth, nutrient content, nodulation and water-stress tolerance was related to the Sinorhizobium strains and Medicago species. This indicates selective and specific compatibilities between microsymbionts and the common host plant. Differential effects of the mycorrhizal isolates were not associated with their colonizing ability. Nodulation and mycorrhizal dependency (MD) changed in each plant genotype in accordance with the Sinorhizobium strain and AM fungi involved. Generally, Medicago sp. MD decreased under water-stress conditions even when these conditions did not affect AM colonization (%). Proline accumulation in non-mycorrhizal plant leaves was increased by water stress, except in M. rotata plants. Differences in proline accumulation in AM-colonized plants suggest that both the AM fungus and the Sinorhizobium strain were able to induce different degrees of osmotic adjustment. Mycorrhizal plants nodulated by the WT strain accumulated more proline in M. rigidula and M. rotata under water stress than non-mycorrhizal plants. Conversely, mycorrhizal plants nodulated by the GM strain accumulated less proline in response to both AM colonization and drought. These results indicated changes in the synthesis of this nitrogenous osmoregulator product associated with microbial inoculation and drought tolerance. Mycorrhizal plants nodulated by the GM Sinorhizobium strain seem to suffer less from the detrimental effect of water stress, since under water limitation relative plant growth

  6. A FIELD STUDY WITH GENETICALLY ENGINEERED ALFALFA INOCULATED WITH RECOMBINANT SINORHIZOBIUM MELILOTI: EFFECTS ON THE SOIL ECOSYSTEM

    Science.gov (United States)

    The agricultural use of genetically engineered plants and microorganisms has become increasingly common. Because genetically engineered plants and microorganisms can produce compounds foreign to their environment, there is concern that they may become established outside of thei...

  7. A highly conserved protein of unknown function in Sinorhizobium meliloti affects sRNA regulation similar to Hfq

    OpenAIRE

    Pandey, Shree P.; Minesinger, Brenda K.; Kumar, Janesh; Walker, Graham C.

    2011-01-01

    The SMc01113/YbeY protein, belonging to the UPF0054 family, is highly conserved in nearly every bacterium. However, the function of these proteins still remains elusive. Our results show that SMc01113/YbeY proteins share structural similarities with the MID domain of the Argonaute (AGO) proteins, and might similarly bind to a small-RNA (sRNA) seed, making a special interaction with the phosphate on the 5′-side of the seed, suggesting they may form a component of the bacterial sRNA pathway. In...

  8. Cloning and Identification of Ammonia Monooxygenase Gene of Sinorhizobium sp. NP1%中华根瘤菌NP1氨单加氧酶基因的克隆与功能鉴定

    Institute of Scientific and Technical Information of China (English)

    刘钰莹; 邱枫; 宋琴; 窦鑫; 许雷

    2010-01-01

    以中华根瘤菌NP1(Sinorhizobium sp.NP1)为原始菌株,通过同源克隆与Tail-PCR方法,获得1 089 bp的氨单加氧酶基因(amo)全长序列.该基因编码362个氨基酸,其二级结构与Sinorhizobium meliloti 1021 AMO的二级结构相似,该蛋白有9个跨膜区段.以自杀穿梭质粒pJQ200SK为原始载体,构建NP1 amo基因敲除质粒pJQ200SK-amo-Tc.采用三亲本杂交的方法将该质粒转入原始菌株NP1中,获得amo基因敲除菌株NP1∷amo.通过本贝洛氏(Berthelot)法对氨氮进行测定,发现NP1∷amo的脱氮效率比原始菌株NP1下降约35%.该结果表明,本实验中所克隆的氨单加氧酶基因为脱氮关键酶基因.

  9. Rhizobium meliloti mutants that overproduce the R. meliloti acidic Calcofluor-binding exopolysaccharide

    International Nuclear Information System (INIS)

    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

  10. Alfalfa microsymbionts from different ITS and nodC lineages of Ensifer meliloti and Ensifer medicae symbiovar meliloti establish efficient symbiosis with alfalfa in Spanish acid soils.

    Science.gov (United States)

    Ramírez-Bahena, Martha-Helena; Vargas, Margarita; Martín, María; Tejedor, Carmen; Velázquez, Encarna; Peix, Álvaro

    2015-06-01

    Alfalfa (Medicago sativa L.) is an important crop worldwide whose cropping in acid soils is hampered by the poor nodulation and yield commonly attributed to the sensitivity of its endosymbionts to acid pH. In this work, we isolated several acid-tolerant strains from alfalfa nodules in three acid soils in northwestern Spain. After grouping by RAPD fingerprinting, most strains were identified as Ensifer meliloti and only two strains as Ensifer medicae according to their 16S-23S intergenic spacer (ITS) sequences that allowed the differentiation of two groups within each one of these species. The two ITS groups of E. meliloti and the ITS group I of E. medicae have been previously found in Medicago nodules; however, the group II of E. medicae has been only found to date in Prosopis alba nodules. The analysis of the nodC gene showed that all strains isolated in this study belong to the symbiovar meliloti, grouping with the type strains of E. meliloti or E. medicae, but some harboured nodC gene alleles different from those found to date in alfalfa nodules. The strains of E. medicae belong to the symbiovar meliloti which should be also recognised in this species, although they harboured a nodC allele phylogenetically divergent to those from E. meliloti strains. Microcosm experiments showed that inoculation of alfalfa with selected acid-tolerant strains significantly increased yields in acid soils representing a suitable agricultural practice for alfalfa cropping in these soils. PMID:25586575

  11. Biochemical characterization of a fructokinase mutant of Rhizobium meliloti.

    OpenAIRE

    Gardiol, A; Arias, A.; Cerveñansky, C; Gaggero, C; Martínez-Drets, G

    1980-01-01

    A double mutant strain (UR3) of Rhizobium meliloti L5-30 was isolated from a phosphoglucose isomerase mutant (UR1) on the basis of its resistance to fructose inhibition when grown on fructose-rich medium. UR3 lacked both phosphoglucose isomerase and fructokinase activity. A mutant strain (UR4) lacking only the fructokinase activity was derived from UR3; it grew on the same carbon sources as the parent strain, but not on fructose, mannitol, or sorbitol. A spontaneous revertant (UR5) of normal ...

  12. Bacterial Molecular Signals in the Sinorhizobium fredii-Soybean Symbiosis

    Directory of Open Access Journals (Sweden)

    Francisco J. López-Baena

    2016-05-01

    Full Text Available Sinorhizobium (Ensifer fredii (S. fredii is a rhizobial species exhibiting a remarkably broad nodulation host-range. Thus, S. fredii is able to effectively nodulate dozens of different legumes, including plants forming determinate nodules, such as the important crops soybean and cowpea, and plants forming indeterminate nodules, such as Glycyrrhiza uralensis and pigeon-pea. This capacity of adaptation to different symbioses makes the study of the molecular signals produced by S. fredii strains of increasing interest since it allows the analysis of their symbiotic role in different types of nodule. In this review, we analyze in depth different S. fredii molecules that act as signals in symbiosis, including nodulation factors, different surface polysaccharides (exopolysaccharides, lipopolysaccharides, cyclic glucans, and K-antigen capsular polysaccharides, and effectors delivered to the interior of the host cells through a symbiotic type 3 secretion system.

  13. Structure and biological roles of Sinorhizobium fredii HH103 exopolysaccharide.

    Science.gov (United States)

    Rodríguez-Navarro, Dulce N; Rodríguez-Carvajal, Miguel A; Acosta-Jurado, Sebastián; Soto, María J; Margaret, Isabel; Crespo-Rivas, Juan C; Sanjuan, Juan; Temprano, Francisco; Gil-Serrano, Antonio; Ruiz-Sainz, José E; Vinardell, José M

    2014-01-01

    Here we report that the structure of the Sinorhizobium fredii HH103 exopolysaccharide (EPS) is composed of glucose, galactose, glucuronic acid, pyruvic acid, in the ratios 5∶2∶2∶1 and is partially acetylated. A S. fredii HH103 exoA mutant (SVQ530), unable to produce EPS, not only forms nitrogen fixing nodules with soybean but also shows increased competitive capacity for nodule occupancy. Mutant SVQ530 is, however, less competitive to nodulate Vigna unguiculata. Biofilm formation was reduced in mutant SVQ530 but increased in an EPS overproducing mutant. Mutant SVQ530 was impaired in surface motility and showed higher osmosensitivity compared to its wild type strain in media containing 50 mM NaCl or 5% (w/v) sucrose. Neither S. fredii HH103 nor 41 other S. fredii strains were recognized by soybean lectin (SBL). S. fredii HH103 mutants affected in exopolysaccharides (EPS), lipopolysaccharides (LPS), cyclic glucans (CG) or capsular polysaccharides (KPS) were not significantly impaired in their soybean-root attachment capacity, suggesting that these surface polysaccharides might not be relevant in early attachment to soybean roots. These results also indicate that the molecular mechanisms involved in S. fredii attachment to soybean roots might be different to those operating in Bradyrhizobium japonicum. PMID:25521500

  14. A 13C-NMR study of exopolysaccharide synthesis in Rhizobium meliloti Su47 strain

    Science.gov (United States)

    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.

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

    OpenAIRE

    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.

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

    OpenAIRE

    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.

  17. Anoxic growth of Ensifer meliloti 1021 by N2O-reduction, a potential mitigation strategy

    OpenAIRE

    Bueno, Emilio; Mania, Daniel; Frostegard, Ǻsa; Bedmar, Eulogio J.; Bakken, Lars R.; Delgado, Maria J.

    2015-01-01

    Denitrification in agricultural soils is a major source of N2O. Legume crops enhance N2O emission by providing N-rich residues, thereby stimulating denitrification, both by free-living denitrifying bacteria and by the symbiont (rhizobium) within the nodules. However, there are limited data concerning N2O production and consumption by endosymbiotic bacteria associated with legume crops. It has been reported that the alfalfa endosymbiont Ensifer meliloti strain 1021, despite possessing and expr...

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

    International Nuclear Information System (INIS)

    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

  19. Functional nodFE genes are present in Sinorhizobium sp. strain MUS10, a symbiont of tropical legume Sesbania rostrata

    Science.gov (United States)

    Sinorhizobium sp. strain MUS10, a rhizobium from the Indian subcontinent, forms nitrogen-fixing nodules on the stems and roots of tropical legume Sesbania rostrata. The structure of Nod factors (NFs) of MUS10 are similar to those of Azorhizobium caulinodans, S. saheli bv sesbaniae and S. terangae bv...

  20. Measurement of the proton motive force in Rhizobium meliloti with the Escherichia coli lacY gene product.

    OpenAIRE

    Gober, J W; Kashket, E R

    1985-01-01

    An Escherichia coli lac operon constitutive for lacY was subcloned into the EcoRI site of a wide-host-range plasmid of the Q incompatibility group, and the resulting recombinant plasmid was introduced into Tn5-generated Lac- mutants of Rhizobium meliloti. The R. meliloti transconjugants accumulated lactose about 1,000-fold, equivalent to a proton motive force of -170 to -180 mV, not significantly different from the values calculated from the distributions of weak acids and lipophilic cations.

  1. Erwinia herbicola isolates from alfalfa plants may play a role in nodulation of alfalfa by Rhizobium meliloti.

    OpenAIRE

    Handelsman, J; Brill, W J

    1985-01-01

    Erwinia herbicola was isolated from roots of plants derived from surface-sterilized seeds of all alfalfa varieties that were tested. Some of these E. herbicola strains affected nodulation by certain strains of Rhizobium meliloti. In previously published work we presented the isolation of slow-and fast-nodulating variants from a single culture of R. meliloti 102F51. In the absence of E. herbicola, the slow-nodulating variant induced the formation of nodules on alfalfa as rapidly as the faster-...

  2. Anoxic growth of Ensifer meliloti 1021 by N2O-reduction, a potential mitigation strategy

    Science.gov (United States)

    Bueno, Emilio; Mania, Daniel; Frostegard, Ǻsa; Bedmar, Eulogio J.; Bakken, Lars R.; Delgado, Maria J.

    2015-01-01

    Denitrification in agricultural soils is a major source of N2O. Legume crops enhance N2O emission by providing N-rich residues, thereby stimulating denitrification, both by free-living denitrifying bacteria and by the symbiont (rhizobium) within the nodules. However, there are limited data concerning N2O production and consumption by endosymbiotic bacteria associated with legume crops. It has been reported that the alfalfa endosymbiont Ensifer meliloti strain 1021, despite possessing and expressing the complete set of denitrification enzymes, is unable to grow via nitrate respiration under anoxic conditions. In the present study, we have demonstrated by using a robotized incubation system that this bacterium is able to grow through anaerobic respiration of N2O to N2. N2O reductase (N2OR) activity was not dependent on the presence of nitrogen oxyanions or NO, thus the expression could be induced by oxygen depletion alone. When incubated at pH 6, E. meliloti was unable to reduce N2O, corroborating previous observations found in both, extracted soil bacteria and Paracoccus denitrificans pure cultures, where expression of functional N2O reductase is difficult at low pH. Furthermore, the presence in the medium of highly reduced C-substrates, such as butyrate, negatively affected N2OR activity. The emission of N2O from soils can be lowered if legumes plants are inoculated with rhizobial strains overexpressing N2O reductase. This study demonstrates that strains like E. meliloti 1021, which do not produce N2O but are able to reduce the N2O emitted by other organisms, could act as even better N2O sinks. PMID:26074913

  3. Anoxic growth of Ensifer meliloti 1021 by N2O-reduction, a potential mitigation strategy

    Directory of Open Access Journals (Sweden)

    Emilio eBueno

    2015-05-01

    Full Text Available Denitrification in agricultural soils is a major source of N2O. Legume crops enhance N2O emission by providing N-rich residues, thereby stimulating denitrification, both by free-living denitrifying bacteria and by the symbiont (rhizobium within the nodules. However, there are limited data concerning N2O production and consumption by endosymbiotic bacteria associated with legume crops. It has been reported that the alfalfa endosymbiont Ensifer meliloti strain 1021, despite possessing and expressing the complete set of denitrification enzymes, is unable to grow via nitrate respiration under anoxic conditions. In the present study, we have demonstrated by using a robotized incubation system that this bacterium is able to grow through anaerobic respiration of N2O to N2. N2O reductase (N2OR activity was not dependent on the presence of nitrogen oxyanions or NO, thus the expression could be induced by oxygen depletion alone. When incubated at pH 6, E. meliloti was unable to reduce N2O, corroborating previous observations found in both, extracted soil bacteria and Paracoccus denitrificans pure cultures, where expression of functional N2O reductase is difficult at low pH. Furthermore, the presence in the medium of highly reduced C-substrates, such as butyrate, negatively affected N2OR activity. The emission of N2O from soils can be lowered if legumes plants are inoculated with rhizobial strains overexpressing N2O reductase. This study demonstrates that strains like E. meliloti 1021, which do not produce N2O but are able to reduce the N2O emitted by other organisms, could act as even better N2O sinks.

  4. Anoxic growth of Ensifer meliloti 1021 by N2O-reduction, a potential mitigation strategy.

    Science.gov (United States)

    Bueno, Emilio; Mania, Daniel; Frostegard, Ǻsa; Bedmar, Eulogio J; Bakken, Lars R; Delgado, Maria J

    2015-01-01

    Denitrification in agricultural soils is a major source of N2O. Legume crops enhance N2O emission by providing N-rich residues, thereby stimulating denitrification, both by free-living denitrifying bacteria and by the symbiont (rhizobium) within the nodules. However, there are limited data concerning N2O production and consumption by endosymbiotic bacteria associated with legume crops. It has been reported that the alfalfa endosymbiont Ensifer meliloti strain 1021, despite possessing and expressing the complete set of denitrification enzymes, is unable to grow via nitrate respiration under anoxic conditions. In the present study, we have demonstrated by using a robotized incubation system that this bacterium is able to grow through anaerobic respiration of N2O to N2. N2O reductase (N2OR) activity was not dependent on the presence of nitrogen oxyanions or NO, thus the expression could be induced by oxygen depletion alone. When incubated at pH 6, E. meliloti was unable to reduce N2O, corroborating previous observations found in both, extracted soil bacteria and Paracoccus denitrificans pure cultures, where expression of functional N2O reductase is difficult at low pH. Furthermore, the presence in the medium of highly reduced C-substrates, such as butyrate, negatively affected N2OR activity. The emission of N2O from soils can be lowered if legumes plants are inoculated with rhizobial strains overexpressing N2O reductase. This study demonstrates that strains like E. meliloti 1021, which do not produce N2O but are able to reduce the N2O emitted by other organisms, could act as even better N2O sinks. PMID:26074913

  5. How genetic pressure of Medicago trunculata acts on the molecular selection and population pattern of its favourite symbiotic bacteria, Sinorhizobium sp.?

    OpenAIRE

    Rangin, Cécile; Béna, Gilles; Brunel, Brigitte; Perrineau, Marie-Mathilde; Mauré, Lucette; Mougel, Christophe; Cleyet-Marel, Jean-Claude

    2007-01-01

    Nitrogen-fixing Sinorhizobium sp. bacteria interact with Medicago truncatula plants, forming root nodules in this nitrogen fixation symbiosis. When rhizobia colonize rhizosphere’s legumes, symbiotic specificity is expressed at two levels, among-species for nodulation ability and within-species for nodulation competitivity. We investigated the genetic diversity of 223 Sinorhizobium sp. strains isolated from nodules sampled from four Medicago truncatula fixed lines, each issued from distinct g...

  6. Genetic analysis of the Rhizobium meliloti bacA gene: functional interchangeability with the Escherichia coli sbmA gene and phenotypes of mutants.

    OpenAIRE

    Ichige, A; Walker, G C

    1997-01-01

    The Rhizobium meliloti bacA gene encodes a function that is essential for bacterial differentiation into bacteroids within plant cells in the symbiosis between R. meliloti and alfalfa. An Escherichia coli homolog of BacA, SbmA, is implicated in the uptake of microcin B17, microcin J25 (formerly microcin 25), and bleomycin. When expressed in E. coli with the lacZ promoter, the R. meliloti bacA gene was found to suppress all the known defects of E. coli sbmA mutants, namely, increased resistanc...

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

    International Nuclear Information System (INIS)

    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. Identification of salt-tolerant Sinorhizobium sp. strain BL3 membrane proteins based on proteomics

    DEFF Research Database (Denmark)

    Tanthanuch, Waraporn; Tittabutr, Panlada; Mohammed, Shabaz; Matthiesen, Rune; Yamabhai, Montarop; Manassila, Monchai; Jensen, Ole Noerregaard; Boonkerd, Nantakorn; Teaumroong, Neung

    2010-01-01

    Sinorhizobium sp. BL3 is a salt-tolerant strain that can fix atmospheric nitrogen in symbiosis with leguminous host plants under salt-stress conditions. Since cell membranes are the first barrier to environmental change, it is interesting to explore the membrane proteins within this protective...... barrier under salt stress. The protein contents of membrane-enriched fractions obtained from BL3 were analyzed by nanoflow liquid chromatography interfaced with electrospray ionization tandem mass spectrometry. A total of 105 membrane proteins were identified. These proteins could be classified into 17...... functional categories, the two biggest of which were energy production and conversion, and proteins not in clusters of orthologous groups (COGs). In addition, a comparative analysis of membrane proteins between salt-stressed and non-stressed BL3 cells was conducted using a membrane enrichment method and off...

  9. Symbiotic Properties of Sinorhizobium Fredii, J-TGS50 an Indonesian Soybean Nodule Forming Bacteria

    International Nuclear Information System (INIS)

    Green House experiments were conducted to study symbiotic properties of Sinorhizobium Fredii, J-TGS50. Sinorhizobium Fredii USDA 192, USDA 201, USDA 205, USDA 206, USDA 217 and Bradyrhizobium japonicum USDA 110 were used as references. Yeast extract mannitol broth culture of the bacteria were made and used as inoculation for several local and imported soybean varieties used in this study. Plants were harvested at 20 days after inoculation. Number of nodules were counted, fresh weight of nodules and shoot were determined. S. Fredii J-TGS50 and S. Fredii USDA 192, USDA 201, USDA 205, USDA 206, USDA 217 were found different in their symbiotic properties. S. Fredii J-TGS50 formed nodules on same imported soybean. While there were no nodules obtained from the plant inoculated with S. Fredii USDA 192, USDA 201, USDA 205, USDA 206, USDA 217. S. Fredii J-TGS50 and recommended B. Japonicum USDA 110 formed nodule on several local soybean varieties. There was no differences between those two bacteria either in nodulation efficiency or in the effectiveness of the formed nodules. Results of this study can be concluded that S. Fredii, J-TGS50 is a native to Indonesian soil and it is a promising soybean nodule forming bacteria in Indonesia. Using indigenous bacteria is valuable. Since they are mostly more tolerant and adaptable than the introduced ones. An important aspect for the success of Biological Nitrogen Fixation (BNF) is insight in the structure of indigenous soybean rhizobia populations. Study on the biodiversity of soybean rhizobia was important conducted. (author)

  10. NCBI nr-aa BLAST: CBRC-DRER-26-0161 [SEVENS

    Lifescience Database Archive (English)

    Full Text Available CBRC-DRER-26-0161 ref|NP_384590.1| acyl-CoA synthase [Sinorhizobium meliloti 1021] emb|CAC29432.2| long...-chain acyl-CoA synthetase [Sinorhizobium meliloti] emb|CAC41921.1| PROBABLE LONG-CHAIN-

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

    International Nuclear Information System (INIS)

    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

  12. Lactose inhibits the growth of Rhizobium meliloti cells that contain an actively expressed Escherichia coli lactose operon.

    OpenAIRE

    Timblin, C R; Kahn, M L

    1984-01-01

    Expression of the Escherichia coli lactose operon in Rhizobium meliloti 104A14 made the cells sensitive to the addition of the beta-galactosides lactose, phenyl-beta-D-galactoside, and lactobionic acid. Growth stopped when the beta-galactoside was added and viability decreased modestly during the next few hours, but little cell lysis was observed and the cells appeared normal. Protein synthesis was not inhibited. Growth was inhibited only when beta-galactosidase expression was greater than 16...

  13. Extended region of nodulation genes in Rhizobium meliloti 1021. II. Nucleotide sequence, transcription start sites and protein products

    International Nuclear Information System (INIS)

    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

  14. Toxic effects of arsenic on Sinorhizobium-Medicago sativa symbiotic interaction

    International Nuclear Information System (INIS)

    Recently, the Rhizobium-legume symbiotic interaction has been proposed as an interesting tool in bioremediation. However, little is known about the effect of most common contaminants on this process. The phytotoxic effects of arsenic on nodulation of Medicago sativa have been examined in vitro using the highly arsenic resistant and symbiotically effective Sinorhizobium sp. strain MA11. The bacteria were able to grow on plates containing As concentrations as high as 10 mM. Nevertheless, as little as 25-35 μM arsenite produced a 75% decrease in the total number of nodules, due to a 90% reduction in the number of rhizobial infections, as could be determined using the strain MA11 carrying a lacZ reporter gene. This effect was associated to root hair damage and a shorter infective root zone. However, once nodulation was established nodule development seemed to continue normally, although earlier senescence could be observed in nodules of arsenic-grown plants. - First steps of nodulation of alfalfa, in particular infection thread formation, are more sensitive to As than nitrogen fixation due to plant effects

  15. Toxic effects of arsenic on Sinorhizobium-Medicago sativa symbiotic interaction

    Energy Technology Data Exchange (ETDEWEB)

    Pajuelo, Eloisa [Department of Microbiology and Parasitology, Faculty of Pharmacy, University of Seville, 41012 Seville (Spain); Rodriguez-Llorente, Ignacio D. [Department of Microbiology and Parasitology, Faculty of Pharmacy, University of Seville, 41012 Seville (Spain)], E-mail: irodri@us.es; Dary, Mohammed; Palomares, Antonio J. [Department of Microbiology and Parasitology, Faculty of Pharmacy, University of Seville, 41012 Seville (Spain)

    2008-07-15

    Recently, the Rhizobium-legume symbiotic interaction has been proposed as an interesting tool in bioremediation. However, little is known about the effect of most common contaminants on this process. The phytotoxic effects of arsenic on nodulation of Medicago sativa have been examined in vitro using the highly arsenic resistant and symbiotically effective Sinorhizobium sp. strain MA11. The bacteria were able to grow on plates containing As concentrations as high as 10 mM. Nevertheless, as little as 25-35 {mu}M arsenite produced a 75% decrease in the total number of nodules, due to a 90% reduction in the number of rhizobial infections, as could be determined using the strain MA11 carrying a lacZ reporter gene. This effect was associated to root hair damage and a shorter infective root zone. However, once nodulation was established nodule development seemed to continue normally, although earlier senescence could be observed in nodules of arsenic-grown plants. - First steps of nodulation of alfalfa, in particular infection thread formation, are more sensitive to As than nitrogen fixation due to plant effects.

  16. Mutualistic co-evolution of type III effector genes in Sinorhizobium fredii and Bradyrhizobium japonicum.

    Directory of Open Access Journals (Sweden)

    Jeffrey A Kimbrel

    2013-02-01

    Full Text Available Two diametric paradigms have been proposed to model the molecular co-evolution of microbial mutualists and their eukaryotic hosts. In one, mutualist and host exhibit an antagonistic arms race and each partner evolves rapidly to maximize their own fitness from the interaction at potential expense of the other. In the opposing model, conflicts between mutualist and host are largely resolved and the interaction is characterized by evolutionary stasis. We tested these opposing frameworks in two lineages of mutualistic rhizobia, Sinorhizobium fredii and Bradyrhizobium japonicum. To examine genes demonstrably important for host-interactions we coupled the mining of genome sequences to a comprehensive functional screen for type III effector genes, which are necessary for many Gram-negative pathogens to infect their hosts. We demonstrate that the rhizobial type III effector genes exhibit a surprisingly high degree of conservation in content and sequence that is in contrast to those of a well characterized plant pathogenic species. This type III effector gene conservation is particularly striking in the context of the relatively high genome-wide diversity of rhizobia. The evolution of rhizobial type III effectors is inconsistent with the molecular arms race paradigm. Instead, our results reveal that these loci are relatively static in rhizobial lineages and suggest that fitness conflicts between rhizobia mutualists and their host plants have been largely resolved.

  17. Complete genome sequence of the Medicago microsymbiont Ensifer (Sinorhizobium) medicae strain WSM419

    Energy Technology Data Exchange (ETDEWEB)

    Reeve, Wayne [Murdoch University, Perth, Australia; Chain, Patrick S. G. [Lawrence Livermore National Laboratory (LLNL); O' Hara, Graham [Murdoch University, Perth, Australia; Ardley, Julie [Murdoch University, Perth, Australia; Nandesena, Kemanthi [Murdoch University, Perth, Australia; Brau, Lambert [Murdoch University, Perth, Australia; Tiwari, Ravi [Murdoch University, Perth, Australia; Malfatti, Stephanie [Lawrence Livermore National Laboratory (LLNL); Kiss, Hajnalka [Los Alamos National Laboratory (LANL); Lapidus, Alla L. [U.S. Department of Energy, Joint Genome Institute; Copeland, A [U.S. Department of Energy, Joint Genome Institute; Nolan, Matt [U.S. Department of Energy, Joint Genome Institute; Land, Miriam L [ORNL; Hauser, Loren John [ORNL; Chang, Yun-Juan [ORNL; 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; Gollagher, Margaret [Murdoch University, Perth, Australia; Yates, Ron [Murdoch University, Perth, Australia; Dilworth, Michael [Murdoch University, Perth, Australia; Howieson, John [Murdoch University, Perth, Australia

    2010-01-01

    Ensifer (Sinorhizobium) medicae is an effective nitrogen fixing microsymbiont of a diverse range of annual Medicago (medic) species. Strain WSM419 is an aerobic, motile, non-spore forming, Gram-negative rod isolated from a M. murex root nodule collected in Sardinia, Italy in 1981. WSM419 was manufactured commercially in Australia as an inoculant for annual medics during 1985 to 1993 due to its nitrogen fixation, saprophytic competence and acid tolerance properties. Here we describe the basic features of this organism, together with the complete genome sequence, and annotation. This is the first report of a complete genome sequence for a microsymbiont of the group of annual medic species adapted to acid soils. We reveal that its genome size is 6,817,576 bp encoding 6,518 protein-coding genes and 81 RNA only encoding genes. The genome contains a chromosome of size 3,781,904 bp and 3 plasmids of size 1,570,951 bp, 1,245,408 bp and 219,313 bp. The smallest plasmid is a feature unique to this medic microsymbiont.

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

    Directory of Open Access Journals (Sweden)

    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.

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

    Science.gov (United States)

    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

  20. Genetic and structural analysis of the Rhizobium meliloti fixA, fixB, fixC, and fixX genes.

    OpenAIRE

    Earl, C D; Ronson, C W; Ausubel, F M

    1987-01-01

    The fixA, fixB, fixC, and fixX genes of Rhizobium meliloti 1021 constitute an operon and are required for nitrogen fixation in alfalfa nodules. DNA homologous to the R. meliloti fixABC genes is present in all other Rhizobium and Bradyrhizobium species examined, but fixABC-homologous sequences were found in only one free-living diazotroph, Azotobacter vinelandii. To determine whether the fixABCX genes share sequence homology with any of the 17 Klebsiella pneumoniae nif genes, we determined the...

  1. A prevalent alpha-proteobacterium Paracoccus sp. in a population of the Cayenne ticks (Amblyomma cajennense from Rio de Janeiro, Brazil

    Directory of Open Access Journals (Sweden)

    Erik Machado-Ferreira

    2012-01-01

    Full Text Available As Rocky Mountain Spotted Fever is the most common tick-borne disease in South America, the presence of Rickettsia sp. in Amblyomma ticks is a possible indication of its endemicity in certain geographic regions. In the present work, bacterial DNA sequences related to Rickettsia amblyommii genes in A. dubitatum ticks, collected in the Brazilian state of Mato Grosso, were discovered. Simultaneously, Paracoccus sp. was detected in aproximately 77% of A. cajennense specimens collected in Rio de Janeiro, Brazil. This is the first report of Paracoccus sp. infection in a specific tick population, and raises the possibility of these bacteria being maintained and/or transmitted by ticks. Whether Paracoccus sp. represents another group of pathogenic Rhodobacteraceae or simply plays a role in A. cajennense physiology, is unknown. The data also demonstrate that the rickettsial 16S rRNA specific primers used forRickettsia spp. screening can also detect Paracoccus alpha-proteobacteria infection in biological samples. Hence, a PCRRFLP strategy is presented to distinguish between these two groups of bacteria.

  2. Localisation and Functional Analysis of a Manganese Oxidase Protein From the Marine Alpha-Proteobacterium Aurantimonas manganoxydans (sp. SI85-9A1)

    Science.gov (United States)

    Anderson, C. R.; Davis, R.; Tebo, B.

    2007-12-01

    The marine α-proteobacterium SI85-9A1 was isolated in 1985 from the oxic-anoxic transition zone in Sannich Inlet, Vancouver Island, Canada. This organism was originally isolated due to its ability to oxidise manganese from Mn(II) to Mn(IV) oxides. It later proved to have a functional Type I RuBisCO suggesting it can potentially grow autotrophically with Mn(II) acting as the electron donor. Until now the mechanism of Mn(II) oxidation has remained enigmatic although clues from the genome and preliminary experiments suggested SI85-9A1 possessed a manganese oxidase similar to the Mox oxidase produced by Pedomicrobium sp. ACM 3067. Whole cell fractionation techniques were used to localise this protein to the outer membrane where it is loosely bound and can be washed off. Manganese oxidation activity in non-pure crude extracts was analysed using an LBB colorimetric assay and monitoring Mn(III)-pyrophosphate complex formation at 258 nm in a Mn(III) capture assay. Both these assays not only confirmed function but suggested that this protein is extremely active with a manganese oxidation rate approaching 8.9 μM min-1 mg-1. Partial FPLC purification confirmed that this protein was approximately 50 KD in size and may be part of a larger holoenzyme.

  3. Diglyceride Kinase Activity in Cell Extracts of Rhizobium meliloti: Evidence for a Diglyceride Cycle during Cyclic β-1,2-Glucan Biosynthesis

    OpenAIRE

    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.

  4. Functional analysis of the cysteine motifs in the ferredoxin-like protein FdxN of Rhizobium meliloti involved in symbiotic nitrogen fixation.

    Science.gov (United States)

    Masepohl, B; Kutsche, M; Riedel, K U; Schmehl, M; Klipp, W; Pühler, A

    1992-05-01

    The Rhizobium meliloti fdxN gene, which is part of the nifA-nifB-fdxN operon, is absolutely required for symbiotic nitrogen fixation. The deduced sequence of the FdxN protein is characterized by two cysteine motifs typical of bacterial-type ferredoxins. The Fix-phenotype of an R. meliloti fdxN::[Tc] mutant could be rescued by the R. leguminosarum fdxN gene, whereas no complementation was observed with nif-associated genes encoding ferredoxins from Bradyrhizobium japonicum, Azotobacter vinelandii, A. chroococcum and Rhodobacter capsulatus. In addition to these heterologous genes, several R. meliloti fdxN mutant genes constructed by site-directed mutagenesis were analyzed. Not only a cysteine residue within the second cysteine motif (position 42), which is known to coordinate the Fe-S cluster in homologous proteins, but also a cysteine located down-stream of this motif (position 61), was found to be essential for the activity of the R. meliloti FdxN protein. Changing the amino acid residue proline in position 56 into methionine resulted in a FdxN mutant protein with decreased activity, whereas changes in positions 35 (Asp35Glu) and 45 (Gly45Glu) had no significant effect on the function of the FdxN mutant proteins. In contrast to bacterial-type ferredoxins, which contain two identical cysteine motifs of the form C-X2-C-X2-C-X3-C, nif-associated ferredoxins, including R. meliloti FdxN, are characterized by two different cysteine motifs. Six "additional" amino acids separate the second (Cys42) and the third cysteine (Cys51) in the C-terminal motif (C-X2-C-X8-C-X3-C).(ABSTRACT TRUNCATED AT 250 WORDS) PMID:1603075

  5. Analysis of cellular fatty acids and phenotypic relationships of Agrobacterium, Bradyrhizobium, Mesorhizobium, Rhizobium and Sinorhizobium species using the Sherlock microbial identification system

    OpenAIRE

    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 ...

  6. Regulatory role of the sequences downstream from nodD3 P1 promoter of Rhizobium meliloti

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The 660 bp region between nodD3 P1 promoter and the following coding region of Rhizobium meliloti has been studied.This region is designated "downstream sequences".It consists of two potential open reading frames,ORF1 and ORF2.Studies on the role of the downstream sequences on the activity of nodD3 P1 with nod D3(P1)-lacZ fusion show that deletion of the sequences containing ORF2 causes the increase of the activity of the fusion; on the contrary,addition of extra copies of ORF2 markedly decreases the activity of the fusion.These results indicate that the product of ORF2 plays a negative role in the expression of nod D3.

  7. N2-Fixation in Alfalfa (Medicago sativa L.) Seedlings and Rhizobium meliloti L. Grown in Vitro Under Salt and Drought Stresses

    OpenAIRE

    Mohamad, Ramzi Muhiddin

    1987-01-01

    Alfalfa, Medicago sativa L., cultivars, breeding lines and germplasm releases (populations) and Rhizobium meliloti L. strains that exhibit nitrogen fixation efficiency and tolerance to salinity and drought stresses should enhance seedling establishment, increase yields, reduce nitrogen dependency on petroleum-based nitrogen fertilizers, and allow wider use of irrigated lands in semiarid and a rid regions. In vitro experiments were conducted to determine relative salt (sodium chloride -- NaCl)...

  8. The 32-kilobase exp gene cluster of Rhizobium meliloti directing the biosynthesis of galactoglucan: genetic organization and properties of the encoded gene products.

    OpenAIRE

    Becker, A.; Rüberg, S; Küster, H.; Roxlau, A A; Keller, M; Ivashina, T; H.P. Cheng; Walker, G C; Pühler, A

    1997-01-01

    Proteins directing the biosynthesis of galactoglucan (exopolysaccharide II) in Rhizobium meliloti Rm2011 are encoded by the exp genes. Sequence analysis of a 32-kb DNA fragment of megaplasmid 2 containing the exp gene cluster identified previously (J. Glazebrook and G. C. Walker, Cell 56:661-672, 1989) revealed the presence of 25 open reading frames. Homologies of the deduced exp gene products to proteins of known function suggested that the exp genes encoded four proteins involved in the bio...

  9. The urease structural gene ureA in Rhizobium meliloti is preceded by an open reading frame necessary for urease activity.

    Science.gov (United States)

    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

  10. Effect of irradiation on nitrogen fixation of rhizobium meliloti IV. The efficiency of induced mutants for nitrogen fixation in the field

    International Nuclear Information System (INIS)

    The aim of this study is to approve the efficiency and persistancy of the mutants under field conditions. Three mutants of R.meliloti, commercial inocula ( Nitrogen ) and wild type were grown in yeast mannitol broth till stationary phase. Results showed a variation in the behaviour and persistancy of inoculum in the soil. The effect of all mutants and inocula on plant yield were diminished after four cuts, showing no significant differences between treated and untreated plants

  11. Identification of Sinorhizobium (Ensifer) medicae based on a specific genomic sequence unveiled by M13-PCR fingerprinting.

    Science.gov (United States)

    Dourado, Ana Catarina; Alves, Paula I L; Tenreiro, Tania; Ferreira, Eugénio M; Tenreiro, Rogério; Fareleira, Paula; Crespo, M Teresa Barreto

    2009-12-01

    A collection of nodule isolates from Medicago polymorpha obtained from southern and central Portugal was evaluated by M13-PCR fingerprinting and hierarchical cluster analysis. Several genomic clusters were obtained which, by 16S rRNA gene sequencing of selected representatives, were shown to be associated with particular taxonomic groups of rhizobia and other soil bacteria. The method provided a clear separation between rhizobia and co-isolated non-symbiotic soil contaminants. Ten M13-PCR groups were assigned to Sinorhizobium (Ensifer) medicae and included all isolates responsible for the formation of nitrogen-fixing nodules upon re-inoculation of M. polymorpha test-plants. In addition, enterobacterial repetitive intergenic consensus (ERIC)-PCR fingerprinting indicated a high genomic heterogeneity within the major M13- PCR clusters of S. medicae isolates. Based on nucleotide sequence data of an M13-PCR amplicon of ca. 1500 bp, observed only in S. medicae isolates and spanning locus Smed_3707 to Smed_3709 from the pSMED01 plasmid sequence of S. medicae WSM419 genome's sequence, a pair of PCR primers was designed and used for direct PCR amplification of a 1399-bp sequence within this fragment. Additional in silico and in vitro experiments, as well as phylogenetic analysis, confirmed the specificity of this primer combination and therefore the reliability of this approach in the prompt identification of S. medicae isolates and their distinction from other soil bacteria. PMID:20112226

  12. Isolation and characterization of a Sinorhizobium fredii mutant that cannot utilize proline as the sole carbon and nitrogen source

    Institute of Scientific and Technical Information of China (English)

    HUANG Sheng; BAI Xueliang; MA Qingsheng; TANG Xianlai; WU Bo

    2004-01-01

    Sinorhizobium fredii strain HN01 can use proline as the sole carbon and nitrogen source. A mutant strain GXHN100 unable to catabolize proline was screened from 6000 Tn5gusA5 random insertional mutants of S.fredii strain HN01. Sequencing analysis showed that an open reading frame, named pmrA (proline metabolic relative), was inserted by the Tn5gusA5. A positive clone, named pGXHN100 which containing 3.3kb foreign DNA fragment of S.fredii strain HN01, was isolated from a partial gene library of S.fredii HN01 by colony in situ hybridization. Sequence analysis showed that pGXHN100 contained the entire pmrA gene. The 3.3kb DNA fragment of pGXHN100 was cloned into a broad-host-range cosmid vector pLAFR3 to form plasmid pGXHN200 which was subsequently introduced into GXHN100 to form a complemented strain GXHN200. Plant test showed that GXHN100 was effective and no obvious changes in nitrogenase activity comparing with parental strain. But GXHN100 nodulated 2 days later on soybean and its nodulation efficiency and competitiveness were decreased. The complemented strain GXHN200 restored the nodulation efficiency and competitiveness of GXHN100 to the wild type.

  13. Stable isotope labelling reveals that NaCl stress decreases the production of Ensifer (Sinorhizobium) arboris lipochitooligosaccharide signalling molecules.

    Science.gov (United States)

    Penttinen, Petri; Räsänen, Leena A; Lortet, Gilles; Lindström, Kristina

    2013-12-01

    Ensifer (Sinorhizobium) arboris is a symbiont of salt-tolerant leguminous trees in the genera Acacia and Prosopis that are utilized in the prevention of soil erosion and desertification and in phytoremediation of salinized soil. Signalling between the plant and the rhizobia is essential for the formation of effective symbiosis that increases the success of reclaiming saline sites. We assessed the effect of salt stress on the growth and the production of lipochitooligosaccharide signalling molecules (LCOs) of S. arboris HAMBI 2361, an LCO-overproducing derivative of the S. arboris type strain HAMBI 1552. The strain tolerated NaCl up to 750 mM. To obtain both qualitative and quantitative information on the LCO production under salt stress, we devised a method where LCOs were differentially labelled by stable isotopes of nitrogen, (14)N and (15)N, and analysed by mass spectrometry. Under control conditions, the strain produced altogether 27 structural LCO variants. In 380 mM NaCl, 13 LCO variants were produced in detectable amounts, and six of these were reliably quantified, ranging from one-tenth to one-third of the non-stressed one. PMID:24256411

  14. NCBI nr-aa BLAST: CBRC-DSIM-03-0025 [SEVENS

    Lifescience Database Archive (English)

    Full Text Available of ATP-binding and membrane-spanning domains [Sinorhizobium meliloti 1021] emb|CAC...49257.1| putative surface saccharide exporting ABC transporter protein, consisting of ATP-binding and membrane-spanning domains [Sinorhizobium meliloti 1021] NP_437397.1 1.8 35% ... ...CBRC-DSIM-03-0025 ref|NP_437397.1| putative surface saccharide exporting ABC transporter protein, consisting

  15. DNA同源性分析最终确定新疆中华根瘤菌 (Sinorhizobium xinjiangensis) 为一独立种%SINORHIZOBIUM XINJIANGENSIS AS AN INDEPENDENT SPECIES CONFIRMED BY DNA HOMOLOGY ANALYSIS

    Institute of Scientific and Technical Information of China (English)

    彭桂香; 谭志远; 陈文新

    2000-01-01

    针对S. xinjiangensis分类地位的争议,从新疆再次分离获得34株快生大豆根瘤菌,在16S rDNA PCR-RFLP分析和SDS全细胞蛋白电泳分群的基础上,进行了16S rDNA 全序列相似性和DNA同源性分析.所测4个菌株和S. fredii模式菌株USDA 205的16S rDNA全序列有很高的相似性.而DNA同源性分析说明新分离的菌株代表与原定的S. xinjiangensis为一个DNA同源群.其模式菌株CCBAU 110 与S. fredii的2 株参比菌株USDA 194、2048之间的DNA同源性分别为31.5%和28.7%.S. fredii的模式菌株USDA 205与新分离的菌株代表及原定的S. xinjiangensis的模式菌株和2个参比菌株之间的DNA同源性为20.8%~39%,远低于70%.属于种水平上的差异.按照国际细菌分类委员会以DNA同源性≥70%且△Tm≤5 ℃作为定种的标准,S. xinjiangensis是Sinorhizobium属中不同于S. fredii的一个独立的种. 表3 参20%In this study, based on the results from 16S rDNA PCR-RFLP of 34 fast-growing soybean rhizobia strains isolated from Xinjiang in comparison with several type and reference strains of related species, and SDS-PAGE whole-cell protein patterns of new representative isolates and other strains in Sinorhizobium, new representative isolates were further analyzed by 16S rDNA full sequencing, G+C mol% tests and DNA-DNA hybridization. 4 strains were analyzed by 16S rDNA full sequencing, indicating that type strain CCBAU 110 of S. xinjiangensis and type strain USDA 205 of S. fredii shared high similarity. The DNA homologies indicated that new representative isolates and S. xinjiangensis were of the same DNA homology groups. The DNA homologies between CCBAU 110 and the reference strains of S. fredii: USDA 194, 2048 were 31.5% and 28.7%, respectively. The DNA-DNA hybridization values between USDA 205 and CCBAU 110, 2 reference strains of S. xinjiangensis, representative of new isolates were 20.8%~39%, which confirmed that S. xinjiangensis and S. fredii belonged to the

  16. Quantifying the rate of biofilm growth of S. meliloti strains in microfluidics via the diffusion coefficient of microspheres

    Science.gov (United States)

    Dorian, Matthew; Seitaridou, Effrosyni

    2014-03-01

    Understanding the rate of biofilm growth is essential for studying genes and preventing unwanted biofilms. In this study, the diffusion coefficient (D) of polystyrene microspheres was used to quantify biofilm growth rates of Sinorhizobia meliloti, a nitrogen fixing bacteria that forms a symbiotic relationship with alfalfa plants. Five strains were studied, two wild types (8530 expR+ and 1021) and three mutants in the exopolysaccharide (EPS I, EPS II) synthesis (8530 exoY , 9034 expG , and 9030-2 expA 1); 1021 and 9030-2 expA 1 are known to be unable to form biofilms. Each strain was inserted into a microfluidic channel with the microspheres. As the cultures grew, the spheres' D values were obtained every 24 hours for 4 days using fluorescence microscopy. Although the D values for 9030-2 expA 1 were inconclusive, 8530 expR+ , 8530 exoY , and 9034 expG showed significant decreases in D between 3 days of growth (| z | > 2 . 25 , p 0 . 05), which shows the lack of a structured biofilm community. Thus, D can be used as an indicator of the presence of a biofilm and its development.

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

    Science.gov (United States)

    Jiménez-Guerrero, Irene; Pérez-Montaño, Francisco; 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

  18. fRNAdb Summary: FR001134 [

    Lifescience Database Archive (English)

    Full Text Available FR001134 AB102732,AB102733,AB102734,AB102735,AE007948,AE008167,AE008265,AE008290,AE008980,AE0092 ... s,Agrobacterium rhizogenes,Agrobacterium vitis,Sinorhizobium ... fredii,Sinorhizobium ... meliloti,Rhizobium ... leguminosa ... rum,Rhizobium ... leguminosarum bv. phaseoli,Rhizobium ... leguminosarum ...

  19. The development of plasmid-free strains of Agrobacterium tumefaciens by using incompatibility with a Rhizobium meliloti plasmid to eliminate pAtC58.

    Science.gov (United States)

    Hynes, M F; Simon, R; Pühler, A

    1985-03-01

    Agrobacterium tumefaciens strains LBA275 and LBA290 were cured of their cryptic plasmid pAtC58 by the introduction of the Rhizobium meliloti plasmid pRme41a, which is incompatible with pAtC58. pRme41a and pTiC58, the resident Ti plasmid of LBA275, were subsequently eliminated by growth at supraoptimal temperature (40 degrees C). The resulting plasmid-free Agrobacterium strains, UBAPF1 and UBAPF2, have proved extremely useful for the study of Rhizobium plasmids. The loss of the cryptic plasmid pAtC58 has no effect on the tumor-forming ability of the Agrobacterium strains; when the Ti plasmid is present, normal tumors are formed on Kalanchoe daigremontiana. PMID:4001194

  20. A 4.6 kb DNA region of Rhizobium meliloti involved in determining urease and hydrogenase activities carries the structural genes for urease (ureA, ureB, ureC) interrupted by other open reading frames.

    Science.gov (United States)

    Miksch, G; Arnold, W; Lentzsch, P; Priefer, U B; Pühler, A

    1994-03-01

    A 4.6 kb DNA region of the Rhizobium meliloti strain AK631 was found to contain seven open reading frames (ORFs), all oriented in the same direction. The putative gene products of four of these ORFs were highly homologous to UreA, UreB and UreC of Klebsiella aerogenes, Proteus mirabilis, Proteus vulgaris and Canavalia ensiformis. The overall organisation of the DNA region analysed was ORF1, ureA (ORF2), ORF3, ureB (ORF4), ORF5, ORF6 and ureC (ORF7), indicating that the organisation of the urease structural genes in R. meliloti differs from that of other urease genes so far characterized. ORF1 was incomplete; only the 3' end of the coding region was present. The six complete ORFs coded for polypeptides of 11.1 (UreA), 8.9 (ORF3), 10.8 (UreB), 15.0 (ORF5), 13.8 (ORF6) and 60.7 kDa (UreC). No sequence homology to known polypeptides could be detected for the gene products of ORF1, ORF3, ORF5 and ORF6. Using a lacZ fusion and insertional mutagenesis it was shown that the seven ORFs identified were all located in the same transcription unit. For mutational analysis a resistance gene cassette was introduced into each of the complete ORFs resulting in apolar mutations. Mutations in ureA, ureB and ureC, but not in ORF3, ORF5 and ORF6, abolished urease activity in R. meliloti. The determination of hydrogen uptake in these R. meliloti mutants revealed that only ORF6 and ureB are necessary for hydrogen uptake. PMID:8121412

  1. NCBI nr-aa BLAST: CBRC-CREM-01-1341 [SEVENS

    Lifescience Database Archive (English)

    Full Text Available CBRC-CREM-01-1341 ref|NP_438063.1| C4 -dicarboxylate transport protein [Sinorhizobium meliloti 10 ... 21] sp|P20672|DCTA_RHIME C4 -dicarboxylate transport protein gb|AAA26253.1| C4 - ... zobium meliloti] gb|AAA26248.1| dctA protein emb|CAC4 9923.1| C4 -dicarboxylate transport protein [Sinorhi ...

  2. Molecular Cloning and Characterization of cgt, the Brucella abortus Cyclic β-1,2-Glucan Transporter Gene, and Its Role in Virulence

    OpenAIRE

    Roset, Mara S.; Ciocchini, Andrés E.; Ugalde, Rodolfo A.; Iñón de Iannino, Nora

    2004-01-01

    The animal pathogen Brucella abortus contains a gene cgt, which complemented Sinorhizobium meliloti nodule development (ndvA) and Agrobacterium tumefaciens chromosomal virulence (chvA) mutants. Complemented strains recovered the presence of anionic cyclic β-1,2-glucan, motility, tumor induction in A. tumefaciens, and nodule occupancy in S. meliloti, all traits strictly associated with the presence of cyclic β-1,2-glucan in the periplasm. Nucleotide sequencing revealed that B. abortus cgt cont...

  3. Final report for DOE grant FG02-06ER15805

    Energy Technology Data Exchange (ETDEWEB)

    Gage, Daniel

    2012-05-31

    DOE funding was used to investigate the role of the phosphotransferase system (PTS) in the symbiotic, nodulating bacterium Sinorhizobium meliloti. This system is well studied in several bacterial species. However, it's organization and function in S. meliloti is substantially different than in the those other, well-studied bacteria. The S. meliloti PTS, through our DOE-funded work, has become a model for how this important signal transduction system works in the a-proteobacteria. We have found that the PTS is relatively simple, used for only signal transduction and not transport, and is involved in regulation of carbon metabolism in response to carbon availability and nitrogen availability.

  4. GenBank blastx search result: AK240729 [KOME

    Lifescience Database Archive (English)

    Full Text Available ner membrane protein (hisW), inner membrane ATPase protein (hisV), and histidase (hutH) genes, complete cds. BCT 2e-11 1 ... ...AK240729 J043030H19 AF111939.1 AF111939 Sinorhizobium meliloti periplasmic binding protein (hisX), in

  5. GenBank blastx search result: AK061948 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK061948 001-042-E07 U17226.1 Sinorhizobium meliloti carbon flux regulator (aniA), beta-ketothiolase (phb...A), and acetoacetyl CoA reductase (phbB) genes, complete cds.|BCT BCT 1e-54 +3 ...

  6. GenBank blastx search result: AK059654 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK059654 001-031-C10 U17226.1 Sinorhizobium meliloti carbon flux regulator (aniA), beta-ketothiolase (phb...A), and acetoacetyl CoA reductase (phbB) genes, complete cds.|BCT BCT 2e-69 +1 ...

  7. GenBank blastx search result: AK062233 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK062233 001-047-D10 AY013584.1 Sinorhizobium meliloti fructose 1,6-bisphosphatase (fbp) gene, p ... ype transcriptional regulator (cbbR), coenzyme PQQ synthesis ... protein A (pqqA), coenzyme PQQ synthesis ... protein B ... (pqqB), coenzyme PQQ synthesis ... protein C (pqqC), coenzyme PQQ synthesis ... protein D ...

  8. Gene : CBRC-DRER-26-0474 [SEVENS

    Lifescience Database Archive (English)

    Full Text Available CBRC-DRER-26-0474 Novel UN D UNKNOWN REGB_RHOS4 2e-81 41% ref|NP_384172.1| SENSOR ... HISTIDINE KINA ... TEIN [Sinorhizobium meliloti 1021] emb|CAC41453.1| SENSOR ... HISTIDINE KINASE TRANSMEMBRANE PROTEIN [Sinorhizob ...

  9. Pseudoroseovarius zhejiangensis gen. nov., sp. nov., a novel alpha-proteobacterium isolated from the chemical wastewater, and reclassification of Roseovarius crassostreae as Pseudoroseovarius crassostreae comb. nov., Roseovarius sediminilitoris as Pseudoroseovarius sediminilitoris comb. nov. and Roseovarius halocynthiae as Pseudoroseovarius halocynthiae comb. nov.

    Science.gov (United States)

    Sun, Cong; Pan, Jie; Zhang, Xin-Qi; Su, Yue; Wu, Min

    2015-08-01

    A Gram-stain negative, aerobic, non-motile and ovoid- to rod-shaped bacterial strain, designated JB3(T), was isolated from a wastewater sample collected from the biochemical reaction basin of Haiyan fine chemical factory in Zhejiang, China. Strain JB3(T) was found to grow optimally at pH 7.0-8.0, at 28 °C and in the presence of 1.0-2.0 % (w/v) NaCl. Chemotaxonomic analysis showed that strain JB3(T) contains ubiquinone-10 (>99 %) as the predominant respiratory quinone and C18:1 ω7c (70.9 %) as the most abundant fatty acid. The polar lipids of strain JB3(T) were identified as phosphatidylglycerol, diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylcholine, an aminophospholipid, an unidentified aminolipid, four unidentified phospholipids and three unidentified lipids. The DNA G+C content of strain JB3(T) was determined to be 68.1 mol%. The 16S rRNA gene sequence similarities between the isolate and Roseovarius crassostreae DSM 16950(T), Roseovarius sediminilitoris KCTC 23959(T) and Roseovarius halocynthiae MA1-10(T) were found to be 97.1, 96.8 and 96.2 %, respectively. Morevoer, the similarity between strain JB3(T) and the type strain of the genus Roseovarius (Roseovarius tolerans DSM 11457(T)) was found to be 93.8 %. The phylogenetic trees reconstructed with all three treeing methods showed that strain JB3(T) constituted a different taxon, which was separate from other taxa with validly published names, and formed a cluster with R. crassostreae DSM 16950(T), R. sediminilitoris KCTC 23959(T) and R. halocynthiae MA1-10(T). These three species were not placed within the phylogenetic cluster formed by R. tolerans DSM 11457(T). Differential phenotypic properties, together with the phylogenetic distinctiveness, demonstrated that strain JB3(T) is clearly distinct from species of the genus Roseovarius. On the basis of these features, we propose strain JB3(T) represents a novel species of a novel genus with the name Pseudoroseovarius zhejiangensis gen. nov., sp. nov. The type strain is JB3(T) (=MCCC 1K00457(T) = KCTC 42443(T)). We also propose that R. crassostreae, R. sediminilitoris and R. halocynthiae should be transferred to this new genus as Pseudoroseovarius crassostreae comb. nov., Pseudoroseovarius sediminilitoris comb. nov. and Pseudoroseovarius halocynthiae comb. nov., respectively. PMID:26066711

  10. Phylogenetic Co-Occurrence of ExoR, ExoS, and ChvI, Components of the RSI Bacterial Invasion Switch, Suggests a Key Adaptive Mechanism Regulating the Transition between Free-Living and Host-Invading Phases in Rhizobiales

    OpenAIRE

    Heavner, Mary Ellen; Qiu, Wei-Gang; Cheng, Hai-Ping

    2015-01-01

    Both bacterial symbionts and pathogens rely on their host-sensing mechanisms to activate the biosynthetic pathways necessary for their invasion into host cells. The Gram-negative bacterium Sinorhizobium meliloti relies on its RSI (ExoR-ExoS-ChvI) Invasion Switch to turn on the production of succinoglycan, an exopolysaccharide required for its host invasion. Recent whole-genome sequencing efforts have uncovered putative components of RSI-like invasion switches in many other symbiotic and patho...

  11. Analysis of Simple Sequence Repeats in Genomes of Rhizobia

    Institute of Scientific and Technical Information of China (English)

    GAO Ya-mei; HAN Yi-qiang; TANG Hui; SUN Dong-mei; WANG Yan-jie; WANG Wei-dong

    2008-01-01

    Simple sequence repeats (SSRs) or microsatellites, as genetic markers, are ubiquitous in genomes of various organisms. The analysis of SSR in rhizobia genome provides useful information for a variety of applications in population genetics of rhizobia. We analyzed the occurrences, relative abundance, and relative density of SSRs, the most common in Bradyrhizobium japonicum, Mesorhizobium loti, and Sinorhizobium meliloti genomes se-quenced in the microorganisms tandem repeats database, and SSRs in the three species genomes were compared with each other. The result showed that there were 1 410, 859, and 638 SSRs in B. japonicum, M. loti, and 5. meliloti genomes, respectively. In the genomes of B. japonicum, M. loti, and 5. meliloti, tetranucleotide, pentanucleotide, and hexanucleotide repeats were more abundant and indicated higher mutation rates in these species. The least abundance was mononucleotide repeat. The SSRs type and distribution were similar among these species.

  12. Dicty_cDB: Contig-U12921-1 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available 1( CP000716 |pid:none) Thermosipho melanesiensis BI429... 37 0.64 AP009568_60( AP009568 |pid:none) Welwitschia mirabili...017308 |pid:none) Mycoplasma mobile 163K complete ... 35 2.4 AM286690_1851( AM286...66 |pid:none) Methanothermobacter thermautotr... 33 9.3 CP000852_584( CP000852 |pid:none) Caldivirga maquili...id:none) Clostridium perfringens ATCC 131... 35 2.4 AL591688_762( AL591688 |pid:none) Sinorhizobium melil...philum H-6-12... 33 9.3 AE006469_335( AE006469 |pid:none) Sinorhizobium meliloti 1021 p

  13. ProMEX – a mass spectral reference database for Plant Proteomics

    Directory of Open Access Journals (Sweden)

    Stefanie eWienkoop

    2012-06-01

    Full Text Available The ProMEX database is one of the main collection of annotated tryptic peptides in plant proteomics. The main objective of the ProMEX Database is to provide experimental MS/MS-based information for cell type-specific or subcellular proteomes in Arabidopsis thaliana, Medicago truncatula, Chlamydomonas reinhardtii, Lotus japonicus, Lotus corniculatus, Phaseolus vulgaris, Lycopersicon esculentum, Solanum tuberosum, Nicotiana tabacum, Glycine max, Zea mays, Bradyrhizobium japonicum and Sinorhizobium meliloti. Direct links at the protein level to the most relevant databases are present in ProMEX. Furthermore, the spectral sequence information are linked to their respective pathways and can be viewed in pathway maps.

  14. "Ménage à trois"

    DEFF Research Database (Denmark)

    Ehlers, Bodil K; Grøndahl, Eva; Ronfort, Joëlle; Bataillon, Thomas

    2012-01-01

    both partners. So far these studies have been typically carried out in a single environment. Here, we ask if the genetic correlation between fitness of the host plant Medicago truncatula (Fabaceae) and its bacterial symbiont Sinorhizobium meliloti is affected by the presence/absence of a monoterpene...... (rG= 0.02 ± 0.05 vs. rG= 0.57 ± 0.02). This finding emphasizes the importance of heterogeneity in the biotic environment for understanding the evolution of species interactions....

  15. Dicty_cDB: Contig-U15101-1 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available CP000679_327( CP000679 |pid:none) Caldicellulosiruptor saccharolyt... 186 1e-45 AE009950_1394( AE009950 |pid:none) Pyrococcus furios...pid:none) Sinorhizobium meliloti 1021 com... 176 2e-42 CP000485_1198( CP000485 |pid:none) Bacillus thuringiensi...8( CP000655 |pid:none) Polynucleobacter necessarius sub... 153 1e-35 BX936398_2566( BX936398 |pid:none) Yersinia pseudotuberculosi...*n**kciikstifrmclsnfsgi**l*fgsik**kn tinaytkcve*lhg*yydgfndnscqkisilrqtya*w*mewtig*klvwir...vqv*mflkknh*tk iqny*h*ii*yyyhilvqvqlkpnt*cqnvlsii*flhlmvi*kriv*mhq*lknkk*ki skisylyf*fs own update 2004. 6.23 Homolo

  16. The effect of acidity on the distribution and symbiotic efficiency of rhizobia in Lithuanian soils

    Science.gov (United States)

    Lapinskas, E. B.

    2007-04-01

    The distribution and symbiotic efficiency of nodule bacteria Rhizobium leguminosarum_bv. trifolii F., Sinorhizobium meliloti D., Rhizobium galegae L., and Rhizobium leguminosarum bv. viciae F. in Lithuanian soils as dependent on the soil acidity were studied in the long-term field, pot, and laboratory experiments. The critical and optimal pH values controlling the distribution of rhizobia and the symbiotic nitrogen fixation were determined for every bacterial species. The relationship was found between the soil pH and the nitrogen-fixing capacity of rhizobia. A positive effect of liming of acid soils in combination with inoculation of legumes on the efficiency of symbiotic nitrogen fixation was demonstrated.

  17. Molecular cloning and characterization of cgt, the Brucella abortus cyclic beta-1,2-glucan transporter gene, and its role in virulence.

    Science.gov (United States)

    Roset, Mara S; Ciocchini, Andrés E; Ugalde, Rodolfo A; Iñón de Iannino, Nora

    2004-04-01

    The animal pathogen Brucella abortus contains a gene cgt, which complemented Sinorhizobium meliloti nodule development (ndvA) and Agrobacterium tumefaciens chromosomal virulence (chvA) mutants. Complemented strains recovered the presence of anionic cyclic beta-1,2-glucan, motility, tumor induction in A. tumefaciens, and nodule occupancy in S. meliloti, all traits strictly associated with the presence of cyclic beta-1,2-glucan in the periplasm. Nucleotide sequencing revealed that B. abortus cgt contains a 1,797-bp open reading frame coding for a predicted membrane protein of 599 amino acids (65.9 kDa) that is 58.5 and 59.9% identical to S. meliloti NdvA and A. tumefaciens ChvA, respectively. Additionally, B. abortus cgt, like S. meliloti ndvA and A. tumefaciens chvA possesses ATP-binding motifs and the ABC signature domain features of a typical ABC transporter. Characterization of Cgt was carried out by the construction of null mutants in B. abortus 2308 and S19 backgrounds. Both mutants do not transport cyclic beta-1,2-glucan to the periplasm, as shown by the absence of anionic cyclic glucan, and they display reduced virulence in mice and defective intracellular multiplication in HeLa cells. These results suggest that cyclic beta-1,2-glucan must be transported into the periplasmatic space to exert its action as a virulence factor. PMID:15039351

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

    OpenAIRE

    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...

  19. Molecular Signals Controlling the Inhibition of Nodulation by Nitrate in Medicago truncatula.

    Science.gov (United States)

    van Noorden, Giel E; Verbeek, Rob; Dinh, Quy Dung; Jin, Jian; Green, Alexandra; Ng, Jason Liang Pin; Mathesius, Ulrike

    2016-01-01

    The presence of nitrogen inhibits legume nodule formation, but the mechanism of this inhibition is poorly understood. We found that 2.5 mM nitrate and above significantly inhibited nodule initiation but not root hair curling in Medicago trunatula. We analyzed protein abundance in M. truncatula roots after treatment with either 0 or 2.5 mM nitrate in the presence or absence of its symbiont Sinorhizobium meliloti after 1, 2 and 5 days following inoculation. Two-dimensional gel electrophoresis combined with mass spectrometry was used to identify 106 differentially accumulated proteins responding to nitrate addition, inoculation or time point. While flavonoid-related proteins were less abundant in the presence of nitrate, addition of Nod gene-inducing flavonoids to the Sinorhizobium culture did not rescue nodulation. Accumulation of auxin in response to rhizobia, which is also controlled by flavonoids, still occurred in the presence of nitrate, but did not localize to a nodule initiation site. Several of the changes included defense- and redox-related proteins, and visualization of reactive oxygen species indicated that their induction in root hairs following Sinorhizobium inoculation was inhibited by nitrate. In summary, the presence of nitrate appears to inhibit nodulation via multiple pathways, including changes to flavonoid metabolism, defense responses and redox changes. PMID:27384556

  20. Diversity of endophytic bacteria associated with nodules of two indigenous legumes at different altitudes of the Qilian Mountains in China.

    Science.gov (United States)

    Xu, Lin; Zhang, Yong; Wang, Li; Chen, Weimin; Wei, Gehong

    2014-09-01

    A total of 201 endophytic root nodule-associated bacteria collected from two legumes indigenous to different Qilian Mountain altitudes (Hexi Corridor) were characterized through 16S rDNA polymerase chain reaction (PCR)-restriction fragment length polymorphism, 16S rRNA gene sequence analysis, and enterobacterial repetitive intergenic consensus-PCR clustering. The isolates phylogenetically belonged to 35 species in the Phyllobacterium, Ensifer, Rhizobium, Microvirga, Sphingomonas, Paracoccus, Mycobacterium, Paenibacillus, Cohnella, Sporosarcina, Bacillus, Staphylococcus, Brevibacterium, Xenophilus, Erwinia, Leclercia, Acinetobacter, and Pseudomonas genera. Phylogenetic nodA sequence analysis showed higher similarity to Sinorhizobium meliloti with strains related to the Rhizobium, Sinorhizobium, and Acinetobacter genera. Sequence analysis of the nifH gene revealed that the strains belonging to Xenophilus, Acinetobacter, Phyllobacterium, and Rhizobium had genes similar to those of Mesorhizobium and Sinorhizobium. The results indicated that horizontal gene transfer could have occurred between rhizobia and non-rhizobial endophytes. Canonical correspondence analysis revealed that altitude and host plant species contributed more to the bacterial endosymbiont separation than other ecological factors. This study provided valuable information on the interactions between symbiotic bacteria, non-symbiotic bacteria and their habitats, and thus provided knowledge on their genetic diversity and ecology. PMID:24985194

  1. The Effects of Clinorotation on the Host Plant, Medicago truncatula, and Its Microbial Symbionts

    Directory of Open Access Journals (Sweden)

    Ariel J.C. Dauzart

    2016-02-01

    Full Text Available Understanding the outcome of the plant-microbe symbiosis in altered gravity is vital to developing life support systems for long-distance space travel and colonization of other planets. Thus, the aim of this research was to understand mutualistic relationships between plants and endophytic microbes under the influence of altered gravity. This project utilized the model tripartite relationship among Medicago truncatula ¬– Sinorhizobium meliloti – Rhizophagus irregularis. Plants were inoculated with rhizobial bacteria (S. meliloti, arbuscular mycorrhizal fungi (R. irregularis, or both microbes, and placed on a rotating clinostat. Vertical and horizontal static controls were also performed. Clinorotation significantly reduced M. truncatula dry mass and fresh mass compared to the static controls. The addition of rhizobia treatments under clinorotation also altered total root length and root-to-shoot fresh mass ratio. Nodule size decreased under rhizobia + clinorotation treatment, and nodule density was significantly decreased compared to the vertical treatment. However, inoculation with arbuscular mycorrhizal fungi was shown to increase biomass accumulation and nodule size. Thus, clinorotation significantly affected M. truncatula and its symbiotic relationships with S. meliloti and R. irregularis. In the long term, the results observed in this clinostat study on the changes of plant-microbe mutualism need to be investigated in spaceflight experiments. Thus, careful consideration of the symbiotic microbes of plants should be included in the design of bioregenerative life support systems needed for space travel.

  2. The Effects of Clinorotation on the Host Plant, Medicago truncatula, and Its Microbial Symbionts

    Science.gov (United States)

    Dauzart, Ariel; Vandenbrink, Joshua; Kiss, John

    2016-02-01

    Understanding the outcome of the plant-microbe symbiosis in altered gravity is vital to developing life support systems for long-distance space travel and colonization of other planets. Thus, the aim of this research was to understand mutualistic relationships between plants and endophytic microbes under the influence of altered gravity. This project utilized the model tripartite relationship among Medicago truncatula ¬– Sinorhizobium meliloti – Rhizophagus irregularis. Plants were inoculated with rhizobial bacteria (S. meliloti), arbuscular mycorrhizal fungi (R. irregularis), or both microbes, and placed on a rotating clinostat. Vertical and horizontal static controls were also performed. Clinorotation significantly reduced M. truncatula dry mass and fresh mass compared to the static controls. The addition of rhizobia treatments under clinorotation also altered total root length and root-to-shoot fresh mass ratio. Nodule size decreased under rhizobia + clinorotation treatment, and nodule density was significantly decreased compared to the vertical treatment. However, inoculation with arbuscular mycorrhizal fungi was shown to increase biomass accumulation and nodule size. Thus, clinorotation significantly affected M. truncatula and its symbiotic relationships with S. meliloti and R. irregularis. In the long term, the results observed in this clinostat study on the changes of plant-microbe mutualism need to be investigated in spaceflight experiments. Thus, careful consideration of the symbiotic microbes of plants should be included in the design of bioregenerative life support systems needed for space travel.

  3. Homoserine Lactones Influence the Reaction of Plants to Rhizobia

    Directory of Open Access Journals (Sweden)

    Karl-Heinz Kogel

    2013-08-01

    Full Text Available Bacterial quorum sensing molecules not only grant the communication within bacterial communities, but also influence eukaryotic hosts. N-acyl-homoserine lactones (AHLs produced by pathogenic or beneficial bacteria were shown to induce diverse reactions in animals and plants. In plants, the reaction to AHLs depends on the length of the lipid side chain. Here we investigated the impact of two bacteria on Arabidopsis thaliana, which usually enter a close symbiosis with plants from the Fabaceae (legumes family and produce a long-chain AHL (Sinorhizobium meliloti or a short-chain AHL (Rhizobium etli. We demonstrate that, similarly to the reaction to pure AHL molecules, the impact, which the inoculation with rhizosphere bacteria has on plants, depends on the type of the produced AHL. The inoculation with oxo-C14-HSL-producing S. meliloti strains enhanced plant resistance towards pathogenic bacteria, whereas the inoculation with an AttM lactonase-expressing S. meliloti strain did not. Inoculation with the oxo-C8-HSL-producing R. etli had no impact on the resistance, which is in agreement with our previous hypothesis. In addition, plants seem to influence the availability of AHLs in the rhizosphere. Taken together, this report provides new insights in the role of N-acyl-homoserine lactones in the inter-kingdom communication at the root surface.

  4. Strigolactones in the Rhizobium-legume symbiosis: Stimulatory effect on bacterial surface motility and down-regulation of their levels in nodulated plants.

    Science.gov (United States)

    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. Dicty_cDB: Contig-U10434-1 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available ochondrial-processing peptidase subuni... 80 3e-14 AE008692_1890( AE008692 |pid:none) Zymomonas mobilis subsp. mobili...e-23 AL591785_132( AL591785 |pid:none) Sinorhizobium meliloti 1021 comp... 110 3e-23 CP000463_4718( CP000463...37( CP001034 |pid:none) Natranaerobius thermophilus JW/... 106 4e-22 CP000908_3211( CP000908 |pid:none) Methylob...8_783( CP000088 |pid:none) Thermobifida fusca YX, complete ... 93 6e-18 CP000766_320( CP000766 |pid:none) Ri...e MTYFT1G-... 90 4e-17 CP000117_2333( CP000117 |pid:none) Anabaena variabilis ATC

  6. Optical disassembly of cellular clusters by tunable tug-of-war tweezers

    CERN Document Server

    Bezryadina, Anna; Chen, Joseph C; Chen, Zhigang

    2016-01-01

    Bacterial biofilms underlie many persistent infections, posing major hurdles in antibiotic treatment. Here, we design and demonstrate tug-of-war optical tweezers that can facilitate assessment of cell-cell adhesion - a key contributing factor to biofilm development, thanks to the combined actions of optical scattering and gradient forces. With a customized optical landscape distinct from that of conventional tweezers, not only can such tug-of-war tweezers stably trap and stretch a rod-shaped bacterium in the observing plane, but, more importantly, they can also impose a tunable lateral force that pulls apart cellular clusters without any tethering or mechanical movement. As a proof of principle, we examined a Sinorhizobium meliloti strain that forms robust biofilms and found that the strength of intercellular adhesion depends on the growth medium. This technique may herald new photonic tools for optical manipulation and biofilm study, as well as other biological applications.

  7. Dicty_cDB: Contig-U09565-1 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available um B str. Ekl... 134 2e-30 AE017349_317( AE017349 |pid:none) Cryptococcus neoformans var. neo... 134 3e-...e) Nicotiana tabacum partial mRNA for... 148 2e-34 AE014298_1402( AE014298 |pid:none) Drosophila melano...132 2e-29 CP000679_781( CP000679 |pid:none) Caldicellulosiruptor saccharolyt... 132 2e-29 (Q0TMI7) RecName: ... CP000448_112( CP000448 |pid:none) Syntrophomonas wolfei subsp. wol... 127 5e-28 CP000920_657( CP000920 |pid:none) Strepto...2e-19 M27221_2( M27221 |pid:none) Sinorhizobium meliloti glutamyl-tRNA s... 98 3e

  8. AcEST: DK945049 [AcEST

    Lifescience Database Archive (English)

    Full Text Available R 148 >sp|Q9X5X3|ATCU_SINMW Copper-transporting P-type ATPase OS=Sinorhizobium medicae (strain WSM419) GN=ac...|Q4EPP8|Q4EPP8_LISMO Heavy metal-binding protein OS=Listeria m... 34 3.2 tr|A6AST1|A6AST1_VIBHA Copper-trans..... 31 2.7 sp|Q4X0S7|DPH1_ASPFU Diphthamide biosynthesis protein 1 OS=Asper... 30 4.5 sp|A2VDJ0|T131L_HUMAN Transmembran...P58342|ATCU2_RHIME Copper-transporting ATPase 2 OS=Rhizobium meliloti Align length 75 Score (bit) 34.7 E-val...sophila ... 30 7.8 >sp|P58342|ATCU2_RHIME Copper-transporting ATPase 2 OS=Rhizobium me

  9. The transcriptional activator LdtR from 'Candidatus Liberibacter asiaticus' mediates osmotic stress tolerance.

    Science.gov (United States)

    Pagliai, Fernando A; Gardner, Christopher L; Bojilova, Lora; Sarnegrim, Amanda; Tamayo, Cheila; Potts, Anastasia H; Teplitski, Max; Folimonova, Svetlana Y; Gonzalez, Claudio F; Lorca, Graciela L

    2014-04-01

    The causal agent of Huanglongbing disease, 'Candidatus Liberibacter asiaticus', is a non-culturable, gram negative, phloem-limited α-proteobacterium. Current methods to control the spread of this disease are still limited to the removal and destruction of infected trees. In this study, we identified and characterized a regulon from 'Ca. L. asiaticus' involved in cell wall remodeling, that contains a member of the MarR family of transcriptional regulators (ldtR), and a predicted L,D-transpeptidase (ldtP). In Sinorhizobium meliloti, mutation of ldtR resulted in morphological changes (shortened rod-type phenotype) and reduced tolerance to osmotic stress. A biochemical approach was taken to identify small molecules that modulate LdtR activity. The LdtR ligands identified by thermal shift assays were validated using DNA binding methods. The biological impact of LdtR inactivation by the small molecules was then examined in Sinorhizobium meliloti and Liberibacter crescens, where a shortened-rod phenotype was induced by growth in presence of the ligands. A new method was also developed to examine the effects of small molecules on the viability of 'Ca. Liberibacter asiaticus', using shoots from HLB-infected orange trees. Decreased expression of ldtRLas and ldtPLas was observed in samples taken from HLB-infected shoots after 6 h of incubation with the LdtR ligands. These results provide strong proof of concept for the use of small molecules that target LdtR, as a potential treatment option for Huanglongbing disease. PMID:24763829

  10. The transcriptional activator LdtR from 'Candidatus Liberibacter asiaticus' mediates osmotic stress tolerance.

    Directory of Open Access Journals (Sweden)

    Fernando A Pagliai

    2014-04-01

    Full Text Available The causal agent of Huanglongbing disease, 'Candidatus Liberibacter asiaticus', is a non-culturable, gram negative, phloem-limited α-proteobacterium. Current methods to control the spread of this disease are still limited to the removal and destruction of infected trees. In this study, we identified and characterized a regulon from 'Ca. L. asiaticus' involved in cell wall remodeling, that contains a member of the MarR family of transcriptional regulators (ldtR, and a predicted L,D-transpeptidase (ldtP. In Sinorhizobium meliloti, mutation of ldtR resulted in morphological changes (shortened rod-type phenotype and reduced tolerance to osmotic stress. A biochemical approach was taken to identify small molecules that modulate LdtR activity. The LdtR ligands identified by thermal shift assays were validated using DNA binding methods. The biological impact of LdtR inactivation by the small molecules was then examined in Sinorhizobium meliloti and Liberibacter crescens, where a shortened-rod phenotype was induced by growth in presence of the ligands. A new method was also developed to examine the effects of small molecules on the viability of 'Ca. Liberibacter asiaticus', using shoots from HLB-infected orange trees. Decreased expression of ldtRLas and ldtPLas was observed in samples taken from HLB-infected shoots after 6 h of incubation with the LdtR ligands. These results provide strong proof of concept for the use of small molecules that target LdtR, as a potential treatment option for Huanglongbing disease.

  11. Microgravity Effects on the Early Events of Biological Nitrogen Fixation in Medicago Truncatula: Results from the SyNRGE Experiment

    Science.gov (United States)

    Stutte, Gary W.; Roberts, Michael S.

    2013-02-01

    SyNRGE (Symbiotic Nodulation in a Reduced Gravity Environment) was a sortie mission on STS-135 in the Biological Research in Canisters (BRIC) hardware to study the effect of μg on a plant-microbe symbiosis resulting in biological nitrogen fixation. Medicago truncatula, a model species for the legume family, was inoculated with its bacterial symbiont, Sinorhizobium meliloti, to observe early biomolecular events associated with infection and nodulation in Petri Dish Fixation Units (PDFU’s). Two sets of experiments were conducted in orbit and in 24-hour delayed ground controls. Experiments were designed to determine if S. meliloti would infect M. truncatula and initiate biomolecular changes associated with nodule formation and if the μg environment altered the host plant and/or bacteria to induce nodule formation upon return to 1g. Initial analysis results demonstrate that the legumes and bacteria cultivated in μg have potential to develop a symbiotic interaction, but suggest that μg alters their ability to form nodules upon return to 1g. (Research supported by NASA ESMD/ Advance Capabilities Division grant NNX10AR09A)

  12. Diversity and numbers of root-nodule bacteria (rhizobia in Polish soils

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    Stefan Martyniuk

    2011-04-01

    Full Text Available Using a sand pouch-plant infection method, populations of several species of root-nodule bacteria (rhizobia were enumerated in eighty soils collected throughout Poland. Rhizobium leguminosarum bv. viciae (symbionts of pea, faba bean, vetch and R. leguminosarum bv. trifolii (symbionts of clover were detected in 77 and 76 soils, respectively. Most of these soils contained moderate and high numbers of these species of the rhizobia. Symbionts of beans, R. leguminosarum bv. phaseoli, were assessed in 76 soils; of this number 15 soils had no detectable populations of bean rhizobia and in 40 soils high or moderate numbers of these bacteria were found. Bradyrhizobium sp. (Lupinus, root-nodule bacteria of lupine and serradella, were absent in 19 soils, out of 80 tested, and 34 soils were colonised by high or moderate populations of bradyrhizobia. Sinorhizobium meliloti, rhizobia nodulating alfalfa, were sparse in the examined soils; with 56 soil containing no detectable numbers of S. meliloti and only 6 soils harbouring high or moderate populations of this species. The estimated numbers of the rhizobia in the studied soils were also related to some physical and chemical properties of these soils.

  13. NPR1 protein regulates pathogenic and symbiotic interactions between Rhizobium and legumes and non-legumes.

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    Smadar Peleg-Grossman

    Full Text Available BACKGROUND: Legumes are unique in their ability to establish symbiotic interaction with rhizobacteria from Rhizobium genus, which provide them with available nitrogen. Nodulation factors (NFs produced by Rhizobium initiate legume root hair deformation and curling that entrap the bacteria, and allow it to grow inside the plant. In contrast, legumes and non-legumes activate defense responses when inoculated with pathogenic bacteria. One major defense pathway is mediated by salicylic acid (SA. SA is sensed and transduced to downstream defense components by a redox-regulated protein called NPR1. METHODOLOGY/PRINCIPAL FINDINGS: We used Arabidopsis mutants in SA defense pathway to test the role of NPR1 in symbiotic interactions. Inoculation of Sinorhizobium meliloti or purified NF on Medicago truncatula or nim1/npr1 A. thaliana mutants induced root hair deformation and transcription of early and late nodulins. Application of S. meliloti or NF on M. truncatula or A. thaliana roots also induced a strong oxidative burst that lasted much longer than in plants inoculated with pathogenic or mutualistic bacteria. Transient overexpression of NPR1 in M. truncatula suppressed root hair curling, while inhibition of NPR1 expression by RNAi accelerated curling. CONCLUSIONS/SIGNIFICANCE: We show that, while NPR1 has a positive effect on pathogen resistance, it has a negative effect on symbiotic interactions, by inhibiting root hair deformation and nodulin expression. Our results also show that basic plant responses to Rhizobium inoculation are conserved in legumes and non-legumes.

  14. EFECTO DE LAS TÉCNICAS DE LAVADO Y FERTILIZACIÓN SOBRE LA SALINIDAD EN SUELOS DEL ALTO VALLE DE RÍO NEGRO Y NEUQUÉN, ARGENTINA Effect of soil leaching techniques and fertilization on the salinity of soils of the upper Río Negro Valley and Neuquén, Argentine

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    Perla Gili S.

    2004-07-01

    Full Text Available El objetivo de este trabajo fue evaluar el efecto de la rehabilitación de suelos por lavado, la aplicación de fertilizante nitrogenado y la inoculación con Sinorhizobium meliloti, para atenuar el estrés salino existente en plantas de alfalfa (Medicago sativa L., sembradas en cinco suelos afectados por sales, pertenecientes al Alto Valle de Río Negro y Neuquén, Argentina. La respuesta de las plantas a las condiciones de salinidad, no sólo depende de la concentración de sales sino también del tipo de sales presentes en el suelo. El tipo de salinidad sódica es la más perjudicial. En los Torrifluventes Típicos (Centenario con alto contenido de sales de NaCl y bajo tenor de materia orgánica, las semillas de alfalfa no germinaron. El lavado de estos suelos disminuyó la conductividad eléctrica desde 6,1 a 1,6 dS m-1, y produjo cambios en la concentración relativa de las sales, favoreciendo el crecimiento de las plantas. La aplicación de nitrato y la inoculación con cepas efectivas de S. meliloti permitió un mejor desarrollo de las plantas de alfalfa, y aumentó la producción de materia seca 16 y 84%, respectivamente. La técnica de rehabilitación de suelo no produjo cambios significativos en el número de S. meliloti (P The objective of this study was to evaluate the effect of soil reclamation by leaching, application of nitrogen fertilizer and inoculation with Sinorhizobium meliloti to reduce saline stress in alfalfa plants (Medicago sativa L. sown in five soils affected by salts, in the Upper Río Negro Valley and Neuquén, Argentina. Plant responses to salinity were not only related on salt concentration but also on the type of salts present in the soil. The sodium saline type of salinity was the most harmful. In the Typic Torrifluvents (Centenario soil with high content of NaCl and low content of organic matter, alfalfa seeds did not germinate. Soil reclamation by leaching reduced the electric conductivity from 6.1 to 1.6 dS m

  15. Effectivenes of inoculation in alfalfa breeding in ecological conditions of the Bjelovar and Bilogora county

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    Darko Uher

    2012-09-01

    Full Text Available Development and basic existence of animal production as well as production of high quality milk depends upon possibility of sufficient production of quality and protein sufficient forage. Forage crop that satisfies these demands is alfalfa which is one of the most important perennial forage crop legumes. The aim of this study was to enhance alfalfa production on acid soil by liming and alfalfa seed inoculation with efficient Sinorhizobium meliloti strains in order to reduce the use of mineral nitrogen fertilization and enable qualitative and cost effective production of forage on the dairy farms. Field trial was established at family farm in the area of Bjelovar and Bilogora county. During two years experimental period statistically significant influence of inoculation and liming on forage and dry matteryield was determined. Significantly the lowest yields were determined on untreated plots without liming material. In all untreated plots, significantly lower yields were determined, but significant differences in yields were also obtained by inoculation with different S. meliloti strains, emphasizing the importance of strains selection used for alfalfa inoculation. In both experimental years total forage yield were ranging from 34 t/ha (untreated plots without liming up to 60 t/ha on plots inoculated with strain 2011 and without liming. Values of total dry matter yield for both experimental years ranged from 6.5 t/ha (untreated plots without liming up to 15,7 t/ha on plots inoculated with strain 2011 without liming. Results of this study showed that application of liming materials for acidity removal had positive effect on alfalfa yields in both experimental years and significantly improved alfalfa production on acid soils. The results of this study clearly showed that inoculation with selected S. meliloti strains may improve alfalfa production on acid soils and may contribute to more efficient forage production for dairy farms under particular

  16. Diverse role of fast growing rhizobia in growth promotion and enhancement of psoralen content in Psoralea corylifolia L

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    Chandra Prabha

    2013-01-01

    Full Text Available Background: Psoralea corylifolia (Bakuchi, a weed, which possesses a highly potent and medicinally important compound psoralen. P. corylifolia has been widely exploited since ages for its biological potential. Materials and Methods: Fifteen root nodulating bacteria as pure culture collection (PCC were isolated from P. corylifolia in India. Further, these strains were evaluated for their effect on the psoralen content in P. corylifolia. High performance liquid chromatography (HPLC method was used for the estimation of psoralen in P. corylifolia seed extracts. The effectiveness of these rhizobial strains was assessed on the basis of screening of various plant growth promoting attributes. Results: The 16S ribosomal RNA sequencing analysis revealed the identity of two most effective rhizobial isolates PCC2 and PCC7 as Rhizobium leguminosarum and Sinorhizobium meliloti, respectively. The R. leguminosarum PCC2 (JN546144 and Ensifer meliloti PCC7 (JN546145 strains showed solubilization of insoluble inorganic phosphate, secreted indole acetic acid (IAA, produced siderophore, showed ACC deaminase activity, and were positive for nodulation and nitrogen fixing genes. Seeds of P. corylifolia were bacterized with combination of R. leguminosarum PCC2 and Ensifer meliloti PCC7 along with their individual application that resulted in enhancement of various early vegetative and late reproduction parameters of plants in two consecutive field trials in the year 2009 and 2010. The psoralen content in the seeds of P. corylifolia was observed to be increased in the field trials where the combination of rhizobial strains PCC2 and PCC7 was used (2.79% compared to control (1.91%. Conclusion: These findings indicate that rhizobial strains PCC2 and PCC7 showing good plant growth promoting attributes can be effective for increasing the psoralen content in the seeds of P. corylifolia to a certain level.

  17. Radiolabeling of lipo-chitooligosaccharides using the NodH sulfotransferase: a two-step enzymatic procedure

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    Ranjeva Raoul

    2004-04-01

    Full Text Available Abstract Background The NodH sulfotransferase from Sinorhizobium meliloti has been used to radiolabel lipochitooligosaccharidic (LCO Nod factor signals with 35S from inorganic sulfate in a two-step enzymatic procedure. The first step involved the production of 3'-phosphoadenosine 5'-phosphosulfate (PAPS, a sulphate donor, using enzymes contained in a yeast extract, and the second step used the NodH enzyme. However with this established procedure, only a low incorporation of the initial inorganic sulfate into the Nod factors was obtained (about 7% after purification of the labeled compounds. The aim of this work was to optimize the radiolabelling of Nod factors with 35S. Results The limiting step has been shown to be the sulfation of ATP and its subsequent conversion into PAPS (first step, the sulfate donor for the NodH sulfotransferase activity (second step. By the addition of GTP to the reaction mixture and by manipulating the [ATP]/[Mg2+] ratio the yield of PAPS has been increased from 13% to 80%. Using the radiolabeled PAPS we have shown that the efficiency of sulfate transfer to LCOs, by the recombinant S. meliloti NodH sulfotransferase is strongly influenced by the length of the oligosaccharide chain. Variations in the substitutions on the non-reducing sugar, including the structure of the fatty acyl chain, had little effect and Nod factors from the heterologous bacterium Rhizobium tropici could be sulfated by NodH from S. meliloti. Conclusions By characterizing the two steps we have optimized the procedure to radiolabel biologically-important, lipo-chitooligosaccharide (LCO Nod factors to a specific radioactivity of about 800 Ci.mmol-1 with an incorporation of 60% of the initial inorganic sulfate. The two-step sulfation procedure may be used to radiolabel a variety of related LCO molecules.

  18. Scanning electron microscopy and in vitro cultivation of endophytic bacteria from potato tubers related to Zebra Chip disease

    Science.gov (United States)

    Zebra chip disease (ZCD) drastically reduces the quality and market value of potatoes in North America. The disease is associated with a phloem-limited alpha-proteobacterium, “Candidatus Liberibacter solanacearum”. No effective measure is currently available to control ZCD. It is known that endoph...

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

    OpenAIRE

    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...

  20. Efecto de la inoculación con bacterias rizosféricas en dos variedades de trigo. Fase II: invernadero Effect of inoculation with rihizospheric bacteria in two varieties of wheat. Phase II: greenhouse

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    Carlos José Bécquer Granados

    Full Text Available Se llevó a cabo un experimento de invernadero para evaluar la influencia de la inoculación simple y combinada, efectuada con las bacterias rizosféricas Sinorhizobium y Azospirillum, en dos variedades de trigo. Materiales y métodos según lo descrito en las metodologías convencionales para este campo de estudio. El diseño experimental fue completamente aleatorizado, con 4 réplicas y 10 tratamientos. Análisis estadístico varianza bifactorial. Se utilizó tratamiento fertilizado con NH4NO3 (150 ppm/kg suelo. Se evaluó contenido de clorofila foliar, peso seco aéreo, peso seco radical, longitud del tallo y germinación. En caso de aparecer diferencias, se determinaron mediante la prueba de Duncan, y las diferencias entre las variedades con t-Student. Se concluye que la inoculación combinada de la cepaA2 (Sinorhizobium meliloti con la cepaN7 (Azospirillum zeae, fue la de mayor influencia positiva en el contenido de clorofila de las plantas. Por otra parte, existió una alta diferenciación entre las dos variedades de trigo en la longitud del tallo, peso seco aéreo y peso seco radical. Los resultados en peso seco aéreo y peso seco radical, al combinarse los dos factores estudiados, dependieron notablemente de las características varietales de la planta y del efecto significativo de la población autóctona de rizobacterias. La germinación de las plantas no estuvo vinculada a ninguno de los factores aplicados en el experimento.The experiment was carried out in a greenhouse so that the inoculation, both simple and combined (with the rhizospheric bacteria- Sinorhizobium andAzospirllium, en two varieties of Wheat. Materials and methodologies were used in accordance with previously prescribed conventional methodologies for this study. The experimental design was completely randomized, with 4 replicas and 10 treatments. A statistical analysis using two-way variance was done. Fertilized treatment was applied with NH4NO3 (150 ppm/kg soil. The

  1. Sulphoacetaldehyde acetyltransferase yields acetyl phosphate: purification from Alcaligenes defragrans and gene clusters in taurine degradation.

    Science.gov (United States)

    Ruff, Jürgen; Denger, Karin; Cook, Alasdair M

    2003-01-15

    The facultatively anaerobic bacterium Alcaligenes defragrans NKNTAU was found to oxidize taurine (2-aminoethanesulphonate) with nitrate as the terminal electron acceptor. Taurine was transaminated to 2-sulphoacetaldehyde. This was not converted into sulphite and acetate by a "sulphoacetaldehyde sulpho-lyase" (EC 4.4.1.12), but into sulphite and acetyl phosphate, which was identified by three methods. The enzyme, which required the addition of phosphate, thiamin diphosphate and Mg(2+) ions for activity, was renamed sulphoacetaldehyde acetyltransferase (Xsc; EC 2.3.1.-). Inducible Xsc was expressed at high levels, and a three-step 11-fold purification yielded an essentially homogeneous soluble protein, which was a homotetramer in its native form; the molecular mass of the subunit was found to be between about 63 kDa (SDS/PAGE) and 65.3 kDa (matrix-assisted laser-desorption ionization-time-of-flight MS). The N-terminal and two internal amino acid sequences were determined, and PCR primers were generated. The xsc gene was amplified and sequenced; the derived molecular mass of the processed protein was 65.0 kDa. The downstream gene presumably encoded the inducible phosphate acetyltransferase (Pta) found in crude extracts. The desulphonative enzymes ("EC 4.4.1.12") from Achromobacter xylosoxidans NCIMB 10751 and Desulfonispora thiosulfatigenes GKNTAU were shown to be Xscs. We detected at least three subclasses of xsc in Proteobacteria and in Gram-positive bacteria, and they comprised a distinct group within the acetohydroxyacid synthase supergene family. Genome sequencing data revealed xsc genes in Burkholderia fungorum (80% sequence identity) and Sinorhizobium meliloti (61%) with closely linked pta genes. Different patterns of regulation for the transport and dissimilation of taurine were hypothesized for S. meliloti and B. fungorum. PMID:12358600

  2. Growth and Nutrient Uptake of Orchardgrass (Dactylis glomerata L. and Meadow Fescue (Festuca pratensis Huds. as Affected by Rhizobacteria

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    Olivera STAJKOVIĆ-SRBINOVIĆ

    2016-06-01

    Full Text Available A diverse group of soil bacteria found in the rhizosphere which can colonize plant roots and improve plant growth are designated as plant growth promoting rhizobacteria. The aim of this study was isolation and screening of different rhizobacterial strains for plant growth promoting characteristics and their ability to improve growth of two grass species, orchardgrass (Dactylis glomerata L. and meadow fescue (Festuca pratensis Huds.. The strains investigated, belonging to the genera Azotobacter, Bacillus, Pseudomonas and rhizobial bacteria, showed various plant growth promoting traits, such as phosphate solubilisation, siderophore production, and indole-3-acetic acid (IAA production. Co-inoculation of meadow fescue with Azotobacter chroococcum A2 and Sinorhizobium meliloti or Pseudomonas sp., and A. chroococcum A5 with S. meliloti, significantly increased shoot dry weight (SDW(25-33%, as well as total N (26-33%, P (24-31% and K (26-28% contents in plants (mg pot-1, compared to uninoculated control. In addition, inoculation of orchardgrass with A. chroococcum strain A1, as well as co-inoculation with B. megaterium and A. chroococcum A1 or A31, significantly increased SDW (51-59% and total N (54-59%, P (51-74% and K (49-55% contents, compared to uninoculated control. Nitrogen percentage in SDW was slightly higher than sufficiency ranges, while K percentage was optimal in all treatments in both species. Phosphorous percentage was lower than sufficiency ranges as a consequence of very low soil P content. The results emphasize the potential of particular rhizobacteria to improve the growth of forage grasses.

  3. Dibenzofuran degradation by Sphingomonas wittichii RW1 under environmental stresses

    OpenAIRE

    Coronado E.

    2013-01-01

    Sphingomonas wittichii is a gram-negative Alpha-proteobacterium, capable of degrading xenobiotic compounds such as dibenzofuran (DBF), dibenzo-p-dioxin, carbazole, 2-hydroxybiphenyl or nitro diphenyl ether herbicides. The metabolism of strain RW1 has been the subject of previous studies and a number of genes involved in DBF degradation have been characterized. It is known that RW1 posseses a unique initial DBF dioxygenase (encoded by the dxnAl gene) that catalyzes the first step in the degrad...

  4. A Transposable Partitioning Locus Used To Stabilize Plasmid-Borne Hydrogen Oxidation and Trifolitoxin Production Genes in a Sinorhizobium Strain

    OpenAIRE

    Kent, Angela D.; Wojtasiak, Michelle L.; Robleto, Eduardo A.; Eric W Triplett

    1998-01-01

    Improved nitrogen-fixing inoculum strains for leguminous crops must be able to effectively compete with indigenous strains for nodulation, enhance legume productivity compared to the productivity obtained with indigenous strains, and maintain stable expression of any added genes in the absence of selection pressure. We constructed a transposable element containing the tfx region for expression of increased nodulation competitiveness and the par locus for plasmid stability. The transposon was ...

  5. Choline uptake in Agrobacterium tumefaciens by the high-affinity ChoXWV transporter.

    Science.gov (United States)

    Aktas, Meriyem; Jost, Kathinka A; Fritz, Christiane; Narberhaus, Franz

    2011-10-01

    Agrobacterium tumefaciens is a facultative phytopathogen that causes crown gall disease. For successful plant transformation A. tumefaciens requires the membrane lipid phosphatidylcholine (PC), which is produced via the methylation and the PC synthase (Pcs) pathways. The latter route is dependent on choline. Although choline uptake has been demonstrated in A. tumefaciens, the responsible transporter(s) remained elusive. In this study, we identified the first choline transport system in A. tumefaciens. The ABC-type choline transporter is encoded by the chromosomally located choXWV operon (ChoX, binding protein; ChoW, permease; and ChoV, ATPase). The Cho system is not critical for growth and PC synthesis. However, [14C]choline uptake is severely reduced in A. tumefaciens choX mutants. Recombinant ChoX is able to bind choline with high affinity (equilibrium dissociation constant [KD] of ≈2 μM). Since other quaternary amines are bound by ChoX with much lower affinities (acetylcholine, KD of ≈80 μM; betaine, KD of ≈470 μM), the ChoXWV system functions as a high-affinity transporter with a preference for choline. Two tryptophan residues (W40 and W87) located in the predicted ligand-binding pocket are essential for choline binding. The structural model of ChoX built on Sinorhizobium meliloti ChoX resembles the typical structure of substrate binding proteins with a so-called "Venus flytrap mechanism" of substrate binding. PMID:21803998

  6. Genomic analyses of metal resistance genes in three plant growth promoting bacteria of legume plants in Northwest mine tailings, China

    Institute of Scientific and Technical Information of China (English)

    Pin Xie; Xiuli Hao; Martin Herzberg; Yantao Luo; Dietrich H.Nies; Gehong Wei

    2015-01-01

    To better understand the diversity of metal resistance genetic determinant from microbes that survived at metal tailings in northwest of China,a highly elevated level of heavy metal containing region,genomic analyses was conducted using genome sequence of three native metal-resistant plant growth promoting bacteria (PGPB).It shows that:Mesorhizobium amorphae CCNWGS0123 contains metal ~nsporters from P-type ATPase,CDF (Cation Diffusion Facilitator),HupE/UreJ and CHR (chromate ion transporter) family involved in copper,zinc,nickel as well as chromate resistance and homeostasis.Meanwhile,the putative CopA/CueO system is expected to mediate copper resistance in Sinorhizobium meliloti CCNWSX0020 while ZntA transporter,assisted with putative CzcD,determines zinc tolerance in Agrobacterium tumefaciens CCNWGS0286.The greenhouse experiment provides the consistent evidence of the plant growth promoting effects of these microbes on their hosts by nitrogen fixation and/or indoleacetic acid (IAA) secretion,indicating a potential in-site phytoremediation usage in the mining tailing regions of China.

  7. Exopolysaccharide production by nitrogen-fixing bacteria within nodules of Medicago plants exposed to chronic radiation in the Chernobyl exclusion zone.

    Science.gov (United States)

    Pawlicki-Jullian, Nathalie; Courtois, Bernard; Pillon, Michelle; Lesur, David; Le Flèche-Mateos, Anne; Laberche, Jean-Claude; Goncharova, Nadia; Courtois, Josiane

    2010-03-01

    Nitrogen-fixing bacteria isolated from root nodules of Medicago plants growing in the 10 km zone around the Chernobyl nuclear power plant were screened for the production of new water-soluble acidic exopolysaccharides (EPSs). The different strains belonged to the Enteriobacteriaceae family (Enterobacter ludwigii, Raoultella terrigena, Klebsiella oxytoca), except for one which belonged to the Rhizobiaceae family (Sinorhizobium meliloti). All of the bacteria produced highly viscous EPS with an average molecular weight comprised between 1 x 10(6) and 3 x 10(6) Da. Five different compositions of EPS were characterized by physico-chemical analyses and (1)H NMR spectroscopy: galactose/mannose (2/1), galactose/glucose (1/1), galactose/glucose/mannose (1/2/1), fucose/galactose/glucose (2/1/1) and fucose/galactose/glucose/mannose (2/2/1/1 or 1/1/2/4). Glucuronic acid, a charged monosaccharide, was also recovered in most of the different EPSs. PMID:20080178

  8. Exploring root symbiotic programs in the model legume Medicago truncatula using EST analysis

    Science.gov (United States)

    Journet, Etienne-Pascal; van Tuinen, Diederik; Gouzy, Jérome; Crespeau, Hervé; Carreau, Véronique; Farmer, Mary-Jo; Niebel, Andreas; Schiex, Thomas; Jaillon, Olivier; Chatagnier, Odile; Godiard, Laurence; Micheli, Fabienne; Kahn, Daniel; Gianinazzi-Pearson, Vivienne; Gamas, Pascal

    2002-01-01

    We report on a large-scale expressed sequence tag (EST) sequencing and analysis program aimed at characterizing the sets of genes expressed in roots of the model legume Medicago truncatula during interactions with either of two microsymbionts, the nitrogen-fixing bacterium Sinorhizobium meliloti or the arbuscular mycorrhizal fungus Glomus intraradices. We have designed specific tools for in silico analysis of EST data, in relation to chimeric cDNA detection, EST clustering, encoded protein prediction, and detection of differential expression. Our 21 473 5′- and 3′-ESTs could be grouped into 6359 EST clusters, corresponding to distinct virtual genes, along with 52 498 other M.truncatula ESTs available in the dbEST (NCBI) database that were recruited in the process. These clusters were manually annotated, using a specifically developed annotation interface. Analysis of EST cluster distribution in various M.truncatula cDNA libraries, supported by a refined R test to evaluate statistical significance and by ‘electronic northern’ representation, enabled us to identify a large number of novel genes predicted to be up- or down-regulated during either symbiotic root interaction. These in silico analyses provide a first global view of the genetic programs for root symbioses in M.truncatula. A searchable database has been built and can be accessed through a public interface. PMID:12490726

  9. Photosynthetic and Molecular Markers of CO2-mediated Photosynthetic Downregulation in Nodulated Alfalfa

    Institute of Scientific and Technical Information of China (English)

    (A)lvaro Sanz-Sáez; Gorka Erice; Iker Aranjuelo; Ricardo Aroca; Juan Manuel Ruíz-Lozano; Jone Aguirreolea; Juan José Irigoyen

    2013-01-01

    Elevated CO2 leads to a decrease in potential net photosynthesis in long-term experiments and thus to a reduction in potential growth.This process is known as photosynthetic downregulation.There is no agreement on the definition of which parameters are the most sensitive for detecting CO2 acclimation.In order to investigate the most sensitive photosynthetic and molecular markers of CO2 acclimation,the effects of elevated CO2,and associated elevated temperature were analyzed in alfalfa plants inoculated with different Sinorhizobium meliloti strains.Plants (Medicago sativa L.cv.Aragón) were grown in summer or autumn in temperature gradient greenhouses (TGG).At the end of the experiment,all plants showed acclimation in both seasons,especially under elevated summer temperatures.This was probably due to the lower nitrogen (N) availability caused by decreased N2-fixation under higher temperatures.Photosynthesis measured at growth CO2 concentration,rubisco in vitro activity and maximum rate of carboxylation were the most sensitive parameters for detecting downregulation.Severe acclimation was also related with decreases in leaf nitrogen content associated with declines in rubisco content (large and small subunits) and activity that resulted in a drop in photosynthesis.Despite the sensitivity of rubisco content as a marker of acclimation,it was not coordinated with gene expression,possibly due to a lag between gene transcription and protein translation.

  10. The destructive citrus pathogen, 'Candidatus Liberibacter asiaticus' encodes a functional flagellin characteristic of a pathogen-associated molecular pattern.

    Directory of Open Access Journals (Sweden)

    Huasong Zou

    Full Text Available Huanglongbing (HLB is presently the most devastating citrus disease worldwide. As an intracellular plant pathogen and insect symbiont, the HLB bacterium, 'Candidatus Liberibacter asiaticus' (Las, retains the entire flagellum-encoding gene cluster in its significantly reduced genome. Las encodes a flagellin and hook-associated protein (Fla of 452 amino acids that contains a conserved 22 amino acid domain (flg22 at positions 29 to 50 in the N-terminus. The phenotypic alteration in motility of a Sinorhizobium meliloti mutant lacking the fla genes was partially restored by constitutive expression of Fla(Las. Agrobacterium-mediated transient expression in planta revealed that Fla(Las induced cell death and callose deposition in Nicotiana benthamiana, and that the transcription of BAK1 and SGT1, which are associated with plant innate immunity, was upregulated. Amino acid substitution experiments revealed that residues 38 (serine and 39 (aspartate of Fla(Las were essential for callose induction. The synthetic flg22(Las peptide could not induce plant cell death but retained the ability to induce callose deposition at a concentration of 20 µM or above. This demonstrated that the pathogen-associated molecular pattern (PAMP activity of flg22 in Las was weaker than those in other well-studied plant pathogenic bacteria. These results indicate that Fla(Las acts as a PAMP and may play an important role in triggering host plant resistance to the HLB bacteria.

  11. Rhizobial peptidase HrrP cleaves host-encoded signaling peptides and mediates symbiotic compatibility.

    Science.gov (United States)

    Price, Paul A; Tanner, Houston R; Dillon, Brett A; Shabab, Mohammed; Walker, Graham C; Griffitts, Joel S

    2015-12-01

    Legume-rhizobium pairs are often observed that produce symbiotic root nodules but fail to fix nitrogen. Using the Sinorhizobium meliloti and Medicago truncatula symbiotic system, we previously described several naturally occurring accessory plasmids capable of disrupting the late stages of nodule development while enhancing bacterial proliferation within the nodule. We report here that host range restriction peptidase (hrrP), a gene found on one of these plasmids, is capable of conferring both these properties. hrrP encodes an M16A family metallopeptidase whose catalytic activity is required for these symbiotic effects. The ability of hrrP to suppress nitrogen fixation is conditioned upon the genotypes of both the host plant and the hrrP-expressing rhizobial strain, suggesting its involvement in symbiotic communication. Purified HrrP protein is capable of degrading a range of nodule-specific cysteine-rich (NCR) peptides encoded by M. truncatula. NCR peptides are crucial signals used by M. truncatula for inducing and maintaining rhizobial differentiation within nodules, as demonstrated in the accompanying article [Horváth B, et al. (2015) Proc Natl Acad Sci USA, 10.1073/pnas.1500777112]. The expression pattern of hrrP and its effects on rhizobial morphology are consistent with the NCR peptide cleavage model. This work points to a symbiotic dialogue involving a complex ensemble of host-derived signaling peptides and bacterial modifier enzymes capable of adjusting signal strength, sometimes with exploitative outcomes. PMID:26401024

  12. Enhanced resistance to nanoparticle toxicity is conferred by overproduction of extracellular polymeric substances

    Energy Technology Data Exchange (ETDEWEB)

    Joshi, Nimisha, E-mail: joshi.nimisha@gmail.com [School of GeoSciences, Microbial Geochemistry Laboratory, University of Edinburgh, West Mains Road, Edinburgh EH9 3JW (United Kingdom); Ngwenya, Bryne T. [School of GeoSciences, Microbial Geochemistry Laboratory, University of Edinburgh, West Mains Road, Edinburgh EH9 3JW (United Kingdom); French, Christopher E. [School of Biological Sciences, Institute of Cell Biology, Darwin Building, University of Edinburgh, Mayfield Road, Edinburgh EH9 3JR (United Kingdom)

    2012-11-30

    Highlights: Black-Right-Pointing-Pointer Demonstration that bacteria engineered for EPS overproduction have better survival against Ag nanotoxicity. Black-Right-Pointing-Pointer EPS destabilises Ag nanoparticles and promotes their aggregation. Black-Right-Pointing-Pointer TEM demonstration that EPS traps the Ag nanoparticles outside the cell. Black-Right-Pointing-Pointer EPS from overexpressing strains offers protection to non-EPS strains of bacteria. Black-Right-Pointing-Pointer EPS polymer analogues such as xanthan also produce a similar response. - Abstract: The increasing production and use of engineered nanoparticles, coupled with their demonstrated toxicity to different organisms, demands the development of a systematic understanding of how nanoparticle toxicity depends on important environmental parameters as well as surface properties of both cells and nanomaterials. We demonstrate that production of the extracellular polymeric substance (EPS), colanic acid by engineered Escherichia coli protects the bacteria against silver nanoparticle toxicity. Moreover, exogenous addition of EPS to a control strain results in an increase in cell viability, as does the addition of commercial EPS polymer analogue xanthan. Furthermore, we have found that an EPS producing strain of Sinorhizobium meliloti shows higher survival upon exposure to silver nanoparticles than the parent strain. Transmission electron microscopy (TEM) observations showed that EPS traps the nanoparticles outside the cells and reduces the exposed surface area of cells to incoming nanoparticles by inducing cell aggregation. Nanoparticle size characterization in the presence of EPS and xanthan indicated a marked tendency towards aggregation. Both are likely effective mechanisms for reducing nanoparticle toxicity in the natural environment.

  13. Enhanced resistance to nanoparticle toxicity is conferred by overproduction of extracellular polymeric substances

    International Nuclear Information System (INIS)

    Highlights: ► Demonstration that bacteria engineered for EPS overproduction have better survival against Ag nanotoxicity. ► EPS destabilises Ag nanoparticles and promotes their aggregation. ► TEM demonstration that EPS traps the Ag nanoparticles outside the cell. ► EPS from overexpressing strains offers protection to non-EPS strains of bacteria. ► EPS polymer analogues such as xanthan also produce a similar response. - Abstract: The increasing production and use of engineered nanoparticles, coupled with their demonstrated toxicity to different organisms, demands the development of a systematic understanding of how nanoparticle toxicity depends on important environmental parameters as well as surface properties of both cells and nanomaterials. We demonstrate that production of the extracellular polymeric substance (EPS), colanic acid by engineered Escherichia coli protects the bacteria against silver nanoparticle toxicity. Moreover, exogenous addition of EPS to a control strain results in an increase in cell viability, as does the addition of commercial EPS polymer analogue xanthan. Furthermore, we have found that an EPS producing strain of Sinorhizobium meliloti shows higher survival upon exposure to silver nanoparticles than the parent strain. Transmission electron microscopy (TEM) observations showed that EPS traps the nanoparticles outside the cells and reduces the exposed surface area of cells to incoming nanoparticles by inducing cell aggregation. Nanoparticle size characterization in the presence of EPS and xanthan indicated a marked tendency towards aggregation. Both are likely effective mechanisms for reducing nanoparticle toxicity in the natural environment.

  14. Improvement of Nitrogen Fixation Efficiency and Plasmid Stability in Bradyrhizobium japonicum by the Introduction of dctABD and parCBA/DE Genes%导入dctABD和parCBA/DE基因提高大豆慢生根瘤菌固氮效率和稳定性的研究

    Institute of Scientific and Technical Information of China (English)

    李友国; 李杰; 刘墨青; 周俊初

    2000-01-01

    以pLAFR3为载体构建重组质粒pHN207,携带有来自苜蓿根瘤菌(Sinorhizobium meliloti)的四碳二羧酸转移酶基因dctABD、来自pTR102的parCBA/DE基因和标记发光酶基因luxAB。利用2亲本杂交法,将重组质粒pHN207导入大豆慢生根瘤菌(Bradyrhizobium japonicum)TA11和CB1809,分别考察了转移接合子中外源重组质粒在人工培养条件和共生条件下的稳定性,结果表明par基因的引入明显提高pLAFR3在TA11和CB1809中的稳定性。dctABD基因可显著提高TA11和CB1809在大豆黑龙33、宁镇一号和渝豆一号上的共生固氮能力,使结瘤植物的地上部分干重(生物量)和总氮量等指标较对照组有显著提高。%ArecombinantplasmidpHN207containingC4-dicarboxylicacidtransport genes(dctABD) from Sinorhizobium meliloti, parCBA/DE genes from pTR102 and reporter genes luxAB from pDB30 was constructed by using pLAFR3 as the vector. The pHN207 was then introduced into the Bradyrhizobium japonicum TA11 and CB1809 by bi-parental mating. It was confirmed that parCBA/DE genes could increase the stability of pLAFR3 in the transconjugants under both free-living and symbiotic condition. The results of plant pot experiment indicated that the introduction of dctABD genes could significantly improve the symbiotic nitrogen fixation efficiency of TA11 and CB1809 with soybean varieties of Heilong 33, Ningzhen No.1 and Yudou No.1. Compared with the control, the shoot dry weight (biomass) and total nitrogen content of the plants tested were significantly increased.

  15. The non-specific lipid transfer protein N5 of Medicago truncatula is implicated in epidermal stages of rhizobium-host interaction

    Directory of Open Access Journals (Sweden)

    Pii Youry

    2012-12-01

    Full Text Available Abstract Background The symbiotic interaction between leguminous plants and rhizobia involves two processes: bacterial infection, resulting in the penetration of bacteria in epidermal and cortical cells, and root nodule organogenesis. Root nodule symbiosis is activated by rhizobial signalling molecules, called Nodulation factors (NFs. NF perception induces the expression of several genes called early nodulins. The early nodulin N5 of Medicago truncatula is a lipid transfer protein that has been shown to positively regulate nodulation although it displays in vitro inhibitory activity against Sinorhizobium meliloti. The purpose of this work was to investigate the role of MtN5 by studying its spatial and temporal pattern of expression during the symbiotic interaction, also in relation to known components of the symbiotic signalling pathway, and by analysing the phenotypic alterations displayed by rhizobia-inoculated MtN5-silenced roots. Results We show here that MtN5 is a NF-responsive gene expressed at a very early phase of symbiosis in epidermal cells and root hairs. MtN5 expression is induced in vitro by rhizobial effector molecules and by auxin and cytokinin, phytohormones involved in nodule organogenesis. Furthermore, lipid signaling is implicated in the response of MtN5 to rhizobia, since the activity of phospholipase D is required for MtN5 induction in S. meliloti-inoculated roots. MtN5-silenced roots inoculated with rhizobia display an increased root hair curling and a reduced number of invaded primordia compared to that in wild type roots, but with no impairment to nodule primordia formation. This phenotype is associated with the stimulation of ENOD11 expression, an early marker of infection, and with the down-regulation of Flotillin 4 (FLOT4, a protein involved in rhizobial entry. Conclusions These data indicate that MtN5 acts downstream of NF perception and upstream of FLOT4 in regulating pre-infection events. The positive effect of MtN5

  16. Fixação do nitrogênio em alfafa nodulada sob supressão e ressuprimento de fósforo Nitrogen fixation in alfalfa nodulated under phosphorus supression and resupply

    Directory of Open Access Journals (Sweden)

    Fernando Teixeira Gomes

    2002-12-01

    Full Text Available Estudaram-se os efeitos da supressão e do ressuprimento de fósforo (Pi sobre a fixação biológica do nitrogênio atmosférico (N2 em plantas de alfafa cv. Flórida 77 inoculadas com Sinorhizobium meliloti, em diferentes estádios do desenvolvimento vegetativo (V3 e V4 e reprodutivo (R6 e R8. O ensaio foi conduzido em casa de vegetação e as plantas cultivadas em solução nutritiva. O período de supressão de Pi por dez dias reduziu os teores de Pi nas folhas e nos nódulos em todos os estádios do desenvolvimento, enquanto nas raízes essa redução somente foi observada nos estádios vegetativos. Após o ressuprimento de Pi à solução nutritiva por igual período, dez dias, foi observada a recuperação nos teores de Pi nos estádios R6 e R8 para folhas, V3 e V4 para raízes e V3 para os nódulos. A supressão de Pi alterou o processo de fixação do N2, estimado pela concentração de aminoácidos totais nas folhas e nas raízes. Os teores de aminoácidos nas folhas e nas raízes foram significativamente menores nas plantas sob supressão de Pi, em relação aos das plantas do tratamento controle. Após o ressuprimento os teores de aminoácidos totais nas raízes, em todos os estádios do desenvolvimento, alcançaram valores similares àqueles das plantas do tratamento controle, enquanto nas folhas isso só ocorreu nos estádios vegetativos. A supressão de Pi não influenciou a proporção de aminoácidos livres na seiva do xilema.Phosphorus (Pi suppression and resupply effects were studied on nitrogen biological fixation (N2 in alfalfa cv. Florida 77 inoculated with Sinorhizobium meliloti in different vegetative (V3 and V4 and reproductive (R6 and R8 stages. The experiment was carried in greenhouse and the plants cultivated in nutritive solution. The inorganic phosphorus (Pi ten days suppression period decreased Pi levels in leaves and nodules in all growth stages, whereas in the roots this decrease was observed only in the

  17. Development of a Microemulsion Formulation for Antimicrobial SecA Inhibitors

    Science.gov (United States)

    Wang, Nian

    2016-01-01

    In our previous study, we have identified five antimicrobial small molecules via structure based design, which inhibit SecA of Candidatus Liberibacter asiaticus (Las). SecA is a critical protein translocase ATPase subunit and is involved in pre-protein translocation across and integration into the cellular membrane in bacteria. In this study, eleven compounds were identified using similarity search method based on the five lead SecA inhibitors identified previously. The identified SecA inhibitors have poor aqueous solubility. Thus a microemulsion master mix (MMX) was developed to address the solubility issue and for application of the antimicrobials. MMX consists of N-methyl-2-pyrrolidone and dimethyl sulfoxide as solvent and co-solvent, as well as polyoxyethylated castor oil, polyalkylene glycol, and polyoxyethylene tridecyl ether phosphate as surfactants. MMX has significantly improved the solubility of SecA inhibitors and has no or little phytotoxic effects at concentrations less than 5.0% (v/v). The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of the SecA inhibitors and streptomycin against eight bacteria including Agrobacterium tumefaciens, Liberibacter crescens, Rhizobium etli, Bradyrhizobium japonicum, Mesorhizobium loti, and Sinorhizobium meliloti phylogenetically related to Las were determined using the broth microdilution method. MIC and MBC results showed that the 16 SecA inhibitors have antibacterial activities comparable to that of streptomycin. Overall, we have identified 11 potent SecA inhibitors using similarity search method. We have developed a microemulsion formulation for SecA inhibitors which improved the antimicrobial activities of SecA inhibitors. PMID:26963811

  18. Molybdate uptake by Agrobacterium tumefaciens correlates with the cellular molybdenum cofactor status.

    Science.gov (United States)

    Hoffmann, Marie-Christine; Ali, Koral; Sonnenschein, Marleen; Robrahn, Laura; Strauss, Daria; Narberhaus, Franz; Masepohl, Bernd

    2016-09-01

    Many enzymes require the molybdenum cofactor, Moco. Under Mo-limiting conditions, the high-affinity ABC transporter ModABC permits molybdate uptake and Moco biosynthesis in bacteria. Under Mo-replete conditions, Escherichia coli represses modABC transcription by the one-component regulator, ModE, consisting of a DNA-binding and a molybdate-sensing domain. Instead of a full-length ModE protein, many bacteria have a shorter ModE protein, ModE(S) , consisting of a DNA-binding domain only. Here, we asked how such proteins sense the intracellular molybdenum status. We show that the Agrobacterium tumefaciens ModE(S) protein Atu2564 is essential for modABC repression. ModE(S) binds two Mo-boxes in the modA promoter as shown by electrophoretic mobility shift assays. Northern analysis revealed cotranscription of modE(S) with the upstream gene, atu2565, which was dispensable for ModE(S) activity. To identify genes controlling ModE(S) function, we performed transposon mutagenesis. Tn5 insertions resulting in derepressed modA transcription mapped to the atu2565-modE(S) operon and several Moco biosynthesis genes. We conclude that A. tumefaciens ModE(S) activity responds to Moco availability rather than to molybdate concentration directly, as is the case for E. coli ModE. Similar results in Sinorhizobium meliloti suggest that Moco dependence is a common feature of ModE(S) regulators. PMID:27196733

  19. Multifunctionality and diversity of culturable bacterial communities strictly associated with spores of the plant beneficial symbiont Rhizophagus intraradices.

    Science.gov (United States)

    Battini, Fabio; Cristani, Caterina; Giovannetti, Manuela; Agnolucci, Monica

    2016-02-01

    Arbuscular Mycorrhizal Fungi (AMF) live in symbiosis with most crop plants and represent essential elements of soil fertility and plant nutrition and productivity, facilitating soil mineral nutrient uptake and protecting plants from biotic and abiotic stresses. These beneficial services may be mediated by the dense and active spore-associated bacterial communities, which sustain diverse functions, such as the promotion of mycorrhizal activity, biological control of soilborne diseases, nitrogen fixation, and the supply of nutrients and growth factors. In this work, we utilised culture-dependent methods to isolate and functionally characterize the microbiota strictly associated to Rhizophagus intraradices spores, and molecularly identified the strains with best potential plant growth promoting (PGP) activities by 16S rDNA sequence analysis. We isolated in pure culture 374 bacterial strains belonging to different functional groups-actinobacteria, spore-forming, chitinolytic and N2-fixing bacteria-and screened 122 strains for their potential PGP activities. The most common PGP trait was represented by P solubilization from phytate (69.7%), followed by siderophore production (65.6%), mineral P solubilization (49.2%) and IAA production (42.6%). About 76% of actinobacteria and 65% of chitinolytic bacteria displayed multiple PGP activities. Nineteen strains with best potential PGP activities, assigned to Sinorhizobium meliloti, Streptomyces spp., Arthrobacter phenanthrenivorans, Nocardiodes albus, Bacillus sp. pumilus group, Fictibacillus barbaricus and Lysinibacillus fusiformis, showed the ability to produce IAA and siderophores and to solubilize P from mineral phosphate and phytate, representing suitable candidates as biocontrol agents, biofertilisers and bioenhancers, in the perspective of targeted management of beneficial symbionts and their associated bacteria in sustainable food production systems. PMID:26805620

  20. Characterization of rhizobia from legumes of agronomic interest grown in semi-arid areas of Central Spain relates genetic differences to soil properties.

    Science.gov (United States)

    Ruiz-Díez, Beatriz; Fajardo, Susana; Felipe, María del Rosario de; Fernández-Pascual, Mercedes

    2012-02-01

    A study of symbiotic bacteria from traditional agricultural legumes from Central Spain was performed to create a collection of rhizobia from soils differing in physicochemical, analytical and/or agroecological properties which could be well-adapted to the environmental conditions of this region, and be used for sustainable agricultural practices. Thirty-six isolates were obtained from root-nodules of fifteen legume species (including Cicer arietinum, Lathyrus sativus, Lens culinaris, Lupinus spp., Medicago sativa, Phaseolus vulgaris, Pisum sativum, and Vicia spp.) from three agriculture areas with soils of different pHs and from a forest area with undisturbed soils. Phenotypical characterization revealed uniformity across the thirty-six isolates, with important exceptions in terms of environmental tolerance (three isolates survived at high temperatures, three at high salinity and three at acid pH). The molecular analysis of 16S rRNA gene showed a close relationship of twenty-nine isolates to Rhizobium leguminosarum, one to Rhizobium gallicum, one to Mesorhizobium ciceri, two to Sinorhizobium (Ensifer) meliloti and three to Bradyrhizobium canariense. The sequence analysis of a symbiosis-specific gene, nod C, showed a correlation with the plant host and grouped twenty-six isolates with Rhizobium leguminosarum bv. viciae, establishing the diversity in relation to legume-host. The 16S-23S rRNA intergenic spacer (IGS) region allowed for intraspecific differentiation, so that strains with equal 16S rRNA were grouped by means of their soil origin. These results indicated that phenotypical and genetically related strains may be widely distributed in this region and that soil abiotic characteristics could have a substantial bearing on the selection of the strains living in each environment. PMID:21953333

  1. utilization of bio fertilizers and organic sources in arable soils under saline conditions using tracer technique

    International Nuclear Information System (INIS)

    Recently, more attention has been paid to conserve and save surrounding environment via minimizing the excessive use of chemical fertilizers and, in general, the agrochemicals applied in heavy quantities in agricultural agroecosystems. Therefore, the attention of most of agronomists was turned towards the use of so called clean agriculture or organic farming. Many of organic systems was pointed out such as the recycling of farm wastes i.e. crop residues, animal manure, organic conditioners for reclamation of soil and in the same time enhancement of plant growth and improving yield quality. The application of organic wastes combined with or without microbial inoculants to plant media are considered as a good management practice in any agricultural production system because it improves, plant quality and soil fertility. Therefore, we have the opportunity to conduct some experiments for achieving the clean agriculture approach, combating the adverse effects of salinity and avoiding the environmental pollution. Series of laboratory and greenhouse experiments were carried out to evaluate the impact of (1) potent isolated fungi (Aspergillus oryzae and Aspergillus terreus) on degrading plant residues (Leucaena and Acacia green parts), and (2) biofertilizers (Sinorhizobium meliloti, Azospirillum brasilense, and Pseudomonas aeruginosa) in assessing barley and spinach plants to combat salinity of soil and irrigation water.15N-tracer technique that considered unique and more reliable technique may benefits in clarifying the responsible mechanisms related to plant growth and gave us the opportunity to quantify the exact amounts of N derived from the different sources of nitrogen available to spinach and barley plants grown on sandy saline soil and irrigated with saline water.

  2. Application of targeted metagenomics to explore abundance and diversity of CO₂-fixing bacterial community using cbbL gene from the rhizosphere of Arachis hypogaea.

    Science.gov (United States)

    Yousuf, Basit; Keshri, Jitendra; Mishra, Avinash; Jha, Bhavanath

    2012-09-10

    Sequestration of CO(2) by autotrophic bacteria is a key process of biogeochemical carbon cycling in soil ecosystem. Rhizosphere is a rich niche of microbial activity and diversity, influenced by change in atmospheric CO(2). Structural changes in rhizosphere composition influence microbial communities and the nutrient cycling. In the present study, the bacterial diversity and population dynamics were established using cbbL and 16S rRNA gene targeted metagenomics approach from the rhizosphere of Arachis hypogaea. A total of 108 cbbL clones were obtained from the rhizospheric soil which revealed predominance of cbbL sequences affiliated to Rhizobium leguminosarum, Bradyrhizobium sp., Sinorhizobium meliloti, Ochrobactrum anthropi and a variety of uncultured cbbL harboring bacteria. The 16S rRNA gene clone library exhibited the dominance of Firmicutes (34.4%), Proteobacteria (18.3%), Actinobacteria (17.2%) and Bacteroidetes (16.1%). About 43% nucleotide sequences of 16S rRNA gene clone library were novel genera which showed <95% homology with published sequences. Gene copy number of cbbL and 16S rRNA genes, determined by quantitative real-time PCR (qRT PCR), was 9.38 ± 0.75 × 10(7) and 5.43 ± 0.79 × 10(8) (per g dry soil), respectively. The results exhibited bacterial community structure with high bacterial diversity and abundance of CO(2)-fixing bacteria, which can be explored further for their role in carbon cycling, sustainable agriculture and environment management. PMID:22766402

  3. Development of a Microemulsion Formulation for Antimicrobial SecA Inhibitors.

    Directory of Open Access Journals (Sweden)

    Jiahuai Hu

    Full Text Available In our previous study, we have identified five antimicrobial small molecules via structure based design, which inhibit SecA of Candidatus Liberibacter asiaticus (Las. SecA is a critical protein translocase ATPase subunit and is involved in pre-protein translocation across and integration into the cellular membrane in bacteria. In this study, eleven compounds were identified using similarity search method based on the five lead SecA inhibitors identified previously. The identified SecA inhibitors have poor aqueous solubility. Thus a microemulsion master mix (MMX was developed to address the solubility issue and for application of the antimicrobials. MMX consists of N-methyl-2-pyrrolidone and dimethyl sulfoxide as solvent and co-solvent, as well as polyoxyethylated castor oil, polyalkylene glycol, and polyoxyethylene tridecyl ether phosphate as surfactants. MMX has significantly improved the solubility of SecA inhibitors and has no or little phytotoxic effects at concentrations less than 5.0% (v/v. The minimum inhibitory concentration (MIC and minimum bactericidal concentration (MBC of the SecA inhibitors and streptomycin against eight bacteria including Agrobacterium tumefaciens, Liberibacter crescens, Rhizobium etli, Bradyrhizobium japonicum, Mesorhizobium loti, and Sinorhizobium meliloti phylogenetically related to Las were determined using the broth microdilution method. MIC and MBC results showed that the 16 SecA inhibitors have antibacterial activities comparable to that of streptomycin. Overall, we have identified 11 potent SecA inhibitors using similarity search method. We have developed a microemulsion formulation for SecA inhibitors which improved the antimicrobial activities of SecA inhibitors.

  4. Development of a Microemulsion Formulation for Antimicrobial SecA Inhibitors.

    Science.gov (United States)

    Hu, Jiahuai; Akula, Nagaraju; Wang, Nian

    2016-01-01

    In our previous study, we have identified five antimicrobial small molecules via structure based design, which inhibit SecA of Candidatus Liberibacter asiaticus (Las). SecA is a critical protein translocase ATPase subunit and is involved in pre-protein translocation across and integration into the cellular membrane in bacteria. In this study, eleven compounds were identified using similarity search method based on the five lead SecA inhibitors identified previously. The identified SecA inhibitors have poor aqueous solubility. Thus a microemulsion master mix (MMX) was developed to address the solubility issue and for application of the antimicrobials. MMX consists of N-methyl-2-pyrrolidone and dimethyl sulfoxide as solvent and co-solvent, as well as polyoxyethylated castor oil, polyalkylene glycol, and polyoxyethylene tridecyl ether phosphate as surfactants. MMX has significantly improved the solubility of SecA inhibitors and has no or little phytotoxic effects at concentrations less than 5.0% (v/v). The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of the SecA inhibitors and streptomycin against eight bacteria including Agrobacterium tumefaciens, Liberibacter crescens, Rhizobium etli, Bradyrhizobium japonicum, Mesorhizobium loti, and Sinorhizobium meliloti phylogenetically related to Las were determined using the broth microdilution method. MIC and MBC results showed that the 16 SecA inhibitors have antibacterial activities comparable to that of streptomycin. Overall, we have identified 11 potent SecA inhibitors using similarity search method. We have developed a microemulsion formulation for SecA inhibitors which improved the antimicrobial activities of SecA inhibitors. PMID:26963811

  5. Kinetics and strain specificity of rhizosphere and endophytic colonization by enteric bacteria on seedlings of Medicago sativa and Medicago truncatula.

    Science.gov (United States)

    Dong, Yuemei; Iniguez, A Leonardo; Ahmer, Brian M M; Triplett, Eric W

    2003-03-01

    The presence of human-pathogenic, enteric bacteria on the surface and in the interior of raw produce is a significant health concern. Several aspects of the biology of the interaction between these bacteria and alfalfa (Medicago sativa) seedlings are addressed here. A collection of enteric bacteria associated with alfalfa sprout contaminations, along with Escherichia coli K-12, Salmonella enterica serotype Typhimurium strain ATCC 14028, and an endophyte of maize, Klebsiella pneumoniae 342, were labeled with green fluorescent protein, and their abilities to colonize the rhizosphere and the interior of the plant were compared. These strains differed widely in their endophytic colonization abilities, with K. pneumoniae 342 and E. coli K-12 being the best and worst colonizers, respectively. The abilities of the pathogens were between those of K. pneumoniae 342 and E. coli K-12. All Salmonella bacteria colonized the interiors of the seedlings in high numbers with an inoculum of 10(2) CFU, although infection characteristics were different for each strain. For most strains, a strong correlation between endophytic colonization and rhizosphere colonization was observed. These results show significant strain specificity for plant entry by these strains. Significant colonization of lateral root cracks was observed, suggesting that this may be the site of entry into the plant for these bacteria. At low inoculum levels, a symbiosis mutant of Medicago truncatula, dmi1, was colonized in higher numbers on the rhizosphere and in the interior by a Salmonella endophyte than was the wild-type host. Endophytic entry of M. truncatula appears to occur by a mechanism independent of the symbiotic infections by Sinorhizobium meliloti or mycorrhizal fungi. PMID:12620870

  6. Low vapour pressure deficit reduces the beneficial effect of elevated CO{sub 2} on growth of N{sub 2}-fixing alfalfa plants

    Energy Technology Data Exchange (ETDEWEB)

    Luis, I. De; Irigoyen, J.J.; Sanchez-Diaz, M. [Univ. de Navarra, Dept. de Fisioligia Vegetal, Pamplona (Spain)

    2002-11-01

    Plant responses to elevated CO{sub 2} can be modified by many environmental factors, but very little attention has been paid to the interaction between CO{sub 2} and changes in vapour pressure deficit (VPD). Thirty-day-old alfalfa plants (Medicago sativa L. cv. Aragon), which were inoculated with Sinorhizobium meliloti 102F78 strain, were grown for 1 month in controlled environment chambers at 25/15 deg C, 14 h photoperiod, and 600 mol m{sup -2} s{sup -1} photosynthetic photon flux (PPF), using a factorial combination of CO{sub 2} concentration (400 mol mol{sup -1} or 700 mol mol{sup -1}) and vapour pressure deficit (0.48 kPa or 1.74 kPa, which corresponded to relative humidities of 85% and 45% at 25 deg C, respectively). Elevated CO{sub 2} strongly stimulated plant growth under high VPD conditions, but this beneficial effect was not observed under low VPD. Under low VPD, elevated CO{sub 2} also did not enhance plant photosynthesis, and plant water stress was greatest for plants grown at elevated CO{sub 2} and low VPD. Moreover, plants grown under elevated CO{sub 2} and low VPD had a lower leaf soluble protein and photosynthetic activity (photosynthetic rate and carboxylation efficiency) than plants grown under elevated CO{sub 2} and high VPD. Elevated CO{sub 2} significantly increased leaf adaxial and abaxial temperatures. Because the effects of elevated CO{sub 2} were dependent on vapour pressure deficit, VPD needs to be controlled in experiments studying the effect of elevated CO{sub 2} as well as considered in the extrapolations of results to a warmer, high-CO{sub 2} world. (au)

  7. On the Unusual Homeoviscous Adaptation of the Membrane Fatty Acyl Components against the Thermal Stress in RhiΖobium meliloti

    International Nuclear Information System (INIS)

    In order to maintain the optimal fluidity in membrane, microorganism genetically regulates the ratio of the unsaturated fatty acids (Ufos) to saturated ones of its biological membrane in response to external perturbing condition such as the change of temperature. The remodelling of fatty acyl chain composition is the most frequently observed response to altered growth temperature. It is reflected in the elevated proportions of unsaturated fatty acid (UFAs) at low temperature. Because cis double bonds, normally positioned at the middle of fatty acyl chains, introduce a kink of approximately 30 .deg. into acyl chain, UFAs pack less compactly and exhibit lower melting points than their saturated homologues. Thus, enrichment of membranes with UFAs offsets, to a significant degree, the increase in membrane order caused by a drop in temperature. This is so called homeoviscous adaptation of the membrane fatty acyl chains against thermal stress. Membrane maintains the optimal viscosity using homeoviscous adaptation.

  8. On the Unusual Homeoviscous Adaptation of the Membrane Fatty Acyl Components against the Thermal Stress in Rhi{Zeta}obium meliloti

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Seb Yung; Jung, Seun Ho [Konkuk University, Seoul (Korea, Republic of); Choi, Yong Hoon; Yang, Chul Hak [Seoul National University, Seoul (Korea, Republic of); Kim, Hyun Won [Yonsei University Wonju College of Medicine, Wonju (Korea, Republic of)

    1999-06-15

    In order to maintain the optimal fluidity in membrane, microorganism genetically regulates the ratio of the unsaturated fatty acids (Ufos) to saturated ones of its biological membrane in response to external perturbing condition such as the change of temperature. The remodelling of fatty acyl chain composition is the most frequently observed response to altered growth temperature. It is reflected in the elevated proportions of unsaturated fatty acid (UFAs) at low temperature. Because cis double bonds, normally positioned at the middle of fatty acyl chains, introduce a kink of approximately 30 .deg. into acyl chain, UFAs pack less compactly and exhibit lower melting points than their saturated homologues. Thus, enrichment of membranes with UFAs offsets, to a significant degree, the increase in membrane order caused by a drop in temperature. This is so called homeoviscous adaptation of the membrane fatty acyl chains against thermal stress. Membrane maintains the optimal viscosity using homeoviscous adaptation.

  9. Identification and Characterization of a Brucella abortus ATP-Binding Cassette Transporter Homolog to Rhizobium meliloti ExsA and Its Role in Virulence and Protection in Mice

    OpenAIRE

    G.M.S. Rosinha; Freitas, Daniela A.; Miyoshi, Anderson; Azevedo, Vasco; Campos, Eleonora; Cravero, Silvio L; Rossetti, Osvaldo; Splitter, Gary; S.C. Oliveira

    2002-01-01

    Brucella abortus is a facultative intracellular bacterial pathogen that causes abortion in domestic animals and undulant fever in humans. The mechanism of virulence of Brucella spp. is not fully understood yet. Furthermore, genes that allow Brucella to reach the intracellular niche and to interact with host cells need to be identified. Using the genomic survey sequence (GSS) approach, we identified the gene encoding an ATP-binding cassette (ABC) transporter of B. abortus strain S2308. The ded...

  10. INCREMENTO EN INVERNADERO DE LA CALIDAD Y CANTIDAD DEL FOLLAJE DE LA ALFALFA (Medicago Sativa L. VARIEDAD FLORIDA 77 CAUSADO POR LA COMBINACIÓN DE FERTILIZACIÓN BIOLÓGICA Y QUÍMICA EN UN SUELO DE LA SERIE BERMEO DE LA SABANA DE BOGOTÁ

    Directory of Open Access Journals (Sweden)

    J. Tovar-Franco

    2006-06-01

    Full Text Available En la Sabana de Bogotá existe la necesidad de incrementar la producción de forrajes que den buen rendimiento, con alta calidad nutricional y que podrían ser un aporte al desarrollo de la industria de concentrados de animales.El objetivo de este trabajo fue establecer el efecto de la inoculación rizobio-hongo micorriza arbuscular (MA sobre la fijación simbiótica de nitrógeno, la absorción de fósforo y el porcentaje de micorrización en alfalfa(Medicago sativa L. en un suelo andept de la serie Bermeo de la Sabana de Bogotá. Se seleccionó la variedad dealfalfa Florida 77 por su adaptabilidad a las condiciones del suelo, la cepa de Rhizobium (Sinorhizobium melilotiGR-4 por su habilidad para mejorar el rendimiento y estimular la fijación simbiótica de nitrógeno en esta variedad y el hongo MA Archaeospora leptoticha por su habilidad para mejorar el rendimiento y estimular la fijación defósforo en esta leguminosa.La inoculación dual (rizobio-hongo MA demostró eficacia de la fertilización biológica, al incrementar significativamente (p<0.05 los efectos del encalado y la fertilización química, aumentando el rendimiento en 26% y al mejorar en el follaje el contenido de nitrógeno (32% y fósforo (28%. Estos resultados destacan el estímulo de los dos microsimbiontes en el aprovechamiento de la fertilización química.La inoculación dual también estimuló la fijación biológica de nitrógeno incrementándose los efectos de la inoculación rizobial al aumentar el rendimiento en 25% y el contenido de nitrógeno del follaje en 22% (p<0.05. También superó el efecto de la inoculación fúngica aumentando el rendimiento en 31% (p<0.05 y la cantidad defósforo absorbido en 34% (p<0.05, demostrándose así los beneficios de la simbiosis tripartita alfalfa-rizobio-hongo MA en este Andisol.

  11. Exploring mitochondrial evolution and metabolism organization principles by comparative analysis of metabolic networks.

    Science.gov (United States)

    Chang, Xiao; Wang, Zhuo; Hao, Pei; Li, Yuan-Yuan; Li, Yi-Xue

    2010-06-01

    The endosymbiotic theory proposed that mitochondrial genomes are derived from an alpha-proteobacterium-like endosymbiont, which was concluded from sequence analysis. We rebuilt the metabolic networks of mitochondria and 22 relative species, and studied the evolution of mitochondrial metabolism at the level of enzyme content and network topology. Our phylogenetic results based on network alignment and motif identification supported the endosymbiotic theory from the point of view of systems biology for the first time. It was found that the mitochondrial metabolic network were much more compact than the relative species, probably related to the higher efficiency of oxidative phosphorylation of the specialized organelle, and the network is highly clustered around the TCA cycle. Moreover, the mitochondrial metabolic network exhibited high functional specificity to the modules. This work provided insight to the understanding of mitochondria evolution, and the organization principle of mitochondrial metabolic network at the network level. PMID:20298776

  12. Mitochondrial genome evolution and the origin of eukaryotes.

    Science.gov (United States)

    Lang, B F; Gray, M W; Burger, G

    1999-01-01

    Recent results from ancestral (minimally derived) protists testify to the tremendous diversity of the mitochondrial genome in various eukaryotic lineages, but also reinforce the view that mitochondria, descendants of an endosymbiotic alpha-Proteobacterium, arose only once in evolution. The serial endosymbiosis theory, currently the most popular hypothesis to explain the origin of mitochondria, postulates the capture of an alpha-proteobacterial endosymbiont by a nucleus-containing eukaryotic host resembling extant amitochondriate protists. New sequence data have challenged this scenario, instead raising the possibility that the origin of the mitochondrion was coincident with, and contributed substantially to, the origin of the nuclear genome of the eukaryotic cell. Defining more precisely the alpha-proteobacterial ancestry of the mitochondrial genome, and the contribution of the endosymbiotic event to the nuclear genome, will be essential for a full understanding of the origin and evolution of the eukaryotic cell as a whole. PMID:10690412

  13. Frequency of infection with A and B supergroup Wolbachia in insects and pests associated with mulberry and silkworm

    Indian Academy of Sciences (India)

    B M Prakash; H P Puttaraju

    2007-06-01

    Wolbachia is a ubiquitous, Gram-negative, vertically transmitted, alpha-proteobacterium that causes an array of reproductive abnormalities including cytoplasmic incompatibility, feminization of genetic males, parthenogenesis in a number of insect species, among others. Wolbachia is now being exploited as an agent for pest and vector control. Previous surveys indicated that it is commonly seen in 16–76% of arthropods. In this paper, using polymerase chain reaction assay based on specific amplification of the ftsZ-A and -B supergroup Wolbachia gene fragments, we found that 30% of insects and pests screened were positive for Wolbachia. Among them 66.7% harbour double Wolbachia infection, while 33.3% harbour single Wolbachia infection. These results indicate widespread infection with both double and single Wolbachia, and provide a wealth of information to exploit this endobacterium for the management of pests and vectors.

  14. NCBI nr-aa BLAST: CBRC-CBRE-01-0167 [SEVENS

    Lifescience Database Archive (English)

    Full Text Available CBRC-CBRE-01-0167 ref|YP_001327006.1| phage tape measure protein [Sinorhizobium med...icae WSM419] gb|ABR60171.1| phage tape measure protein [Sinorhizobium medicae WSM419] YP_001327006.1 2.9 26% ...

  15. Effects of Effective Microbial Inoculants on Alfalfa Growth Character%苜蓿根际有益菌接种剂对苜蓿生长特性影响的研究

    Institute of Scientific and Technical Information of China (English)

    韩华雯; 孙丽娜; 姚拓; 张英; 王国基

    2013-01-01

    为探讨微生物肥源替代或部分替代化肥的应用潜力,利用前期从苜蓿(Medicago sativa L.)和小麦(Triticum aestivum L.)根际分离的3株溶磷菌(Bacillus sp.,Pseudomonas sp.和Azotobacter sp.)和1株根瘤菌(Sinorhizobium meliloti)研制苜蓿根际新型专用接种剂,并进行田间随机区组试验,测定其对苜蓿生长特性的影响.结果表明:单一菌种接种剂+半量磷肥对苜蓿的促生效果不及复合菌种接种剂+半量磷肥,与对照(全量磷肥)相比,复合菌种接种剂+半量磷肥处理对苜蓿的各项生长指标均有明显的促生效应,其中以复合接种剂+半量磷肥处理的效果最佳:苜蓿株高、叶绿素含量、叶茎比、干鲜比及产量分别较对照增加9.00%,51.98%,13.79%,19.57%,11.98%(第1茬)和8.26%,48.08%,16.87%,20.07%,20.95%(第2茬);单一菌种接种剂+半量磷肥处理的效果不及全量磷肥处理,但处理根瘤接种剂+半量磷肥效果较好.因此,推荐根瘤接种剂和Jm170+Jm92+ Lx191溶磷菌+根瘤菌复合接种剂为适用于苜蓿的最佳单一及复合菌株接种剂,研制的各接种剂质量达到农业部微生物肥料行业标准(NY227-94)的要求.%Maintenance of soil fertility is one of the more important requirements for sustainable agriculture in China because increasing chemical fertilizer use and highly productive systems has created environmental problems and resource overexploitation. In recent years, bio-fertilizers have emerged as an important component of the integrated nutrient supply system and show great promise to improve crop yields. The objective of this paper is to survey the possibility of applying bio-fertilizers to replace chemical fertilizers. Three phosphate-solubilizing bacteria strains (Bacillus sp. , Pseudomonas sp. and Azotobacter sp. ) and one rhi-zobium (Sinorhizobium meliloti) , isolated from alfalfa and wheat rhizosphere, were used to produce single and compound inoculants. A field

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

    OpenAIRE

    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...

  17. 系列混合碳源条件下颗粒化EBPR系统茵群结构变化规律研究%A study of microbial diversity of granule-based enhanced biological phosphorus removal systems cultivated with ratiometric propionate and acetate as mixed carbon sources

    Institute of Scientific and Technical Information of China (English)

    蒋涛; 孙培德; 金均

    2012-01-01

    A series of mixed carbon sources with different ratios of propionate and acetate was applied in granule-based enhanced biological phosphorus removal (EBPR) sludge in SBR reactor. Microbial diversity change during the granular process and functional bacteria competition under different carbon sources were studied. Significant microbial diversity change in EBPR system was exhibited during granulation. Uncultured bacteria previously dominated in the system disappeared rapidly, while uncultured rhodocyclaceae bacterium and portions of candidatus competibacter phosphatis, denitrifying bacterium, acinetobacter and uncultured alpha proteobacterium were gradually washed out. Uncultured chlorobi bacterium and uncultured alpha proteobacterium were the primary phosphorus removal bacteria in developed granular EBPR system. The change of bacteria population ofcandidatus competibacterphosphatis and uncultured chlorobi bacterium was evidenced as a result of microbial diversity under different ratios of mixed carbon sources. The population of candidatus competibacter phosphatis increased monotonically with acetate concentration, decreaseing the system phosphorus removal efficiency. Meanwhile, the population of uncultured chlorobi bacterium had a positive correlation with propionate concentration, which maintained good phosphorus removal efficiency of the EBPR system.%在SBR反应器中接种富含聚磷菌的活性污泥,采用一系列不同丙酸/乙酸比例混合的碳源进行EBPR系统污泥的颗粒化培养,并考察了颗粒化进程中的系统菌群结构变化,以及不同混合碳源条件对系统功能菌种竞争的影响.结果表明,污泥颗粒化过程对EBPR系统菌群结构产生了较大的筛选作用.原本在系统中占优势的一类Uncultured bacterium被迅速淘汰;Uncultured Rhodocyclaceae bacterium、部分Candidatus Competibacter phosphatis、部分Denitrifying bacterium、Acinetobacter及部分Uncultured alpha proteobacterium分别逐渐被淘

  18. Genetic diversity of rhizobial populations recovered from three Lotus species cultivated in the infra-arid Tunisian soils

    Institute of Scientific and Technical Information of China (English)

    Mokhtar Rejili; Maria José Lorite; Mosbah Mahdhi; Juan Sanjuan Pinilla; Ali Ferchichi; Mohamed Mars

    2009-01-01

    gments from each strain based on the UPGMA algorithm from the combined patterns showed that Lotus isolates are very diverse and that they were affiliated to Sinorhizobium,Rhizobium,and Mesorhizobium genera.

  19. Bacterial study of Vostok drilling fluid: the tool to make ice core finding confident

    Science.gov (United States)

    Alekhina, I. A.; Petit, J. R.; Lukin, V. V.; Bulat, S. A.

    2003-04-01

    Decontamination of Vostok ice core is a critical issue in molecular biology studies. Core surface contains a film of hardly removable 'dirty' drilling fluid representing a mixture of polyhydrocarbons (PHC) including polyaromatic hydrocarbons (PAH) and freon. To make ice microbial finding more confident the original Vostok drilling fluid sampled from different depths (110m - 3600m) was analyzed for bacterial content by ribosomal DNA sequencing. Total, 33 clones of 16S ribosomal DNA were recovered from four samples of drilling fluid at 110, 2750, 3400, and 3600m leading to identification of 8 bacterial species. No overlapping was observed even for neighboring samples (3400m and 3600m). At present four major bacteria with the titer more than 103-104 cells per ml (as estimated from PCR results) are identified. Among them we found: unknown representative of Desulfobacteraceae which are able to oxidize sulphates and degrade benzenes (110m); PAH-degrading alpha-proteobacterium Sphingomonas natatoria (3400m); alpha-proteobacterium representing closely-related group of Sphingomonas sp. (e.g., S. aurantiaca) which are able to degrade PAH as well, and human pathogen closely related to Haloanella gallinarum of CFB group (3600m). Four additional species were revealed as single clones and showed relatedness to human pathogens and saprophytes as well as soil bacteria. These bacteria may represent drilling fluid contaminants introduced during its sampling or DNA extraction procedure. Of four major bacteria revealed, one species, Sphingomonas natatoria, has been met by us in the Vostok core from 3607 m depth (AF532054) whereas another Sphingomonas sp. which we refer to as S. aurantiaca was found in Antarctic microbial endolithic community (AF548567), hydrocarbon-containing soil near Scott Base in Antarctica (AF184221) and even isolated from 3593m Vostok accretion ice (AF324199) and Taylor Dome core (AF395031). The source for major human pathogen-related bacteria is rather uncertain

  20. The Genome of the Obligately Intracellular Bacterium Ehrlichia canis Reveals Themes of Complex Membrane Structure and Immune Evasion Strategies

    Energy Technology Data Exchange (ETDEWEB)

    Mavromatis, K [U.S. Department of Energy, Joint Genome Institute; Doyle, C Kuyler [Center for Biodenfense and Emerging Infectious Diseases; Lykidis, A [U.S. Department of Energy, Joint Genome Institute; Ivanova, N [U.S. Department of Energy, Joint Genome Institute; Francino, M P [U.S. Department of Energy, Joint Genome Institute; Chain, Patrick S [ORNL; Shin, M [U.S. Department of Energy, Joint Genome Institute; Malfatti, Stephanie [Lawrence Livermore National Laboratory (LLNL); Larimer, Frank W [ORNL; Copeland, A [U.S. Department of Energy, Joint Genome Institute; Detter, J C [U.S. Department of Energy, Joint Genome Institute; Land, Miriam L [ORNL; Richardson, P M [U.S. Department of Energy, Joint Genome Institute; Yu, X J [Center for Biodenfense and Emerging Infectious Diseases; Walker, D H [Center for Biodenfense and Emerging Infectious Diseases; McBride, J W [Center for Biodenfense and Emerging Infectious Diseases; Kyripides, N C [U.S. Department of Energy, Joint Genome Institute

    2006-01-01

    Ehrlichia canis, a small obligately intracellular, tick-transmitted, gram-negative, {alpha}-proteobacterium, is the primary etiologic agent of globally distributed canine monocytic ehrlichiosis. Complete genome sequencing revealed that the E. canis genome consists of a single circular chromosome of 1,315,030 bp predicted to encode 925 proteins, 40 stable RNA species, 17 putative pseudogenes, and a substantial proportion of noncoding sequence (27%). Interesting genome features include a large set of proteins with transmembrane helices and/or signal sequences and a unique serine-threonine bias associated with the potential for O glycosylation that was prominent in proteins associated with pathogen-host interactions. Furthermore, two paralogous protein families associated with immune evasion were identified, one of which contains poly(G-C) tracts, suggesting that they may play a role in phase variation and facilitation of persistent infections. Genes associated with pathogen-host interactions were identified, including a small group encoding proteins (n = 12) with tandem repeats and another group encoding proteins with eukaryote-like ankyrin domains (n = 7).

  1. A new alpha-proteobacterial clade of Bdellovibrio-like predators: implications for the mitochondrial endosymbiotic theory.

    Science.gov (United States)

    Davidov, Yaacov; Huchon, Dorothee; Koval, Susan F; Jurkevitch, Edouard

    2006-12-01

    Bdellovibrio-and-like organisms (BALOs) are peculiar, ubiquitous, small-sized, highly motile Gram-negative bacteria that are obligatory predators of other bacteria. Typically, these predators invade the periplasm of their prey where they grow and replicate. To date, BALOs constitute two highly diverse families affiliated with the delta-proteobacteria class. In this study, Micavibrio spp., a BALO lineage of epibiotic predators, were isolated from soil. These bacteria attach to digest and grow at the expense of other prokaryotes, much like other BALOs. Multiple phylogenetic analyses based on six genes revealed that they formed a deep branch within the alpha-proteobacteria, not affiliated with any of the alpha-proteobacterial orders. The presence of BALOs deep among the alpha-proteobacteria suggests that their peculiar mode of parasitism maybe an ancestral character in this proteobacterial class. The origin of the mitochondrion from an alpha-proteobacterium endosymbiont is strongly supported by molecular phylogenies. Accumulating data suggest that the endosymbiont's host was also a prokaryote. As prokaryotes are unable to phagocytose, the means by which the endosymbiont gained access into its host remains mysterious. We here propose a scenario based on the BALO feeding-mode to hypothesize a mechanism at play at the origin of the mitochondrial endosymbiosis. PMID:17107559

  2. Phase Preference by Active, Acetate-Utilizing Bacteria at the Rifle, CO Integrated Field Research Challenge Site

    Energy Technology Data Exchange (ETDEWEB)

    Kerkhof, L.; Williams, K.H.; Long, P.E.; McGuinness, L.

    2011-02-21

    Previous experiments at the Rifle, Colorado Integrated Field Research Challenge (IFRC) site demonstrated that field-scale addition of acetate to groundwater reduced the ambient soluble uranium concentration. In this report, sediment samples collected before and after acetate field addition were used to assess the active microbes via {sup 13}C acetate stable isotope probing on 3 phases [coarse sand, fines (8-approximately 150 {micro}m), groundwater (0.2-8 {micro}m)] over a 24-day time frame. TRFLP results generally indicated a stronger signal in {sup 13}C-DNA in the 'fines' fraction compared to the sand and groundwater. Before the field-scale acetate addition, a Geobacter-like group primarily synthesized {sup 13}C-DNA in the groundwater phase, an alpha Proteobacterium primarily grew on the fines/sands, and an Acinetobacter sp. and Decholoromonas-like OTU utilized much of the {sup 13}C acetate in both groundwater and particle-associated phases. At the termination of the field-scale acetate addition, the Geobacter-like species was active on the solid phases rather than the groundwater, while the other bacterial groups had very reduced newly synthesized DNA signal. These findings will help to delineate the acetate utilization patterns of bacteria in the field and can lead to improved methods for stimulating distinct microbial populations in situ.

  3. Genomic Sequencing and Biological Characteristics of a Novel Escherichia Coli Bacteriophage 9g, a Putative Representative of a New Siphoviridae Genus

    Directory of Open Access Journals (Sweden)

    Eugene E. Kulikov

    2014-12-01

    Full Text Available Bacteriophage 9g was isolated from horse feces using Escherichia coli C600 as a host strain. Phage 9g has a slightly elongated capsid 62 × 76 nm in diameter and a non-contractile tail about 185 nm long. The complete genome sequence of this bacteriophage consists of 56,703 bp encoding 70 predicted open reading frames. The closest relative of phage 9g is phage PhiJL001 infecting marine alpha-proteobacterium associated with Ircinia strobilina sponge, sharing with phage 9g 51% of amino acid identity in the main capsid protein sequence. The DNA of 9g is resistant to most restriction endonucleases tested, indicating the presence of hypermodified bases. The gene cluster encoding a biosynthesis pathway similar to biosynthesis of the unusual nucleoside queuosine was detected in the phage 9g genome. The genomic map organization is somewhat similar to the typical temperate phage gene layout but no integrase gene was detected. Phage 9g efficiently forms stable associations with its host that continues to produce the phage over multiple passages, but the phage can be easily eliminated via viricide treatment indicating that no true lysogens are formed. Since the sequence, genomic organization and biological properties of bacteriophage 9g are clearly distinct from other known Enterobacteriaceae phages, we propose to consider it as the representative of a novel genus of the Siphoviridae family.

  4. Dissection of recognition determinants of Escherichia coli sigma32 suggests a composite -10 region with an 'extended -10' motif and a core -10 element.

    Science.gov (United States)

    Koo, Byoung-Mo; Rhodius, Virgil A; Campbell, Elizabeth A; Gross, Carol A

    2009-05-01

    Sigma32 controls expression of heat shock genes in Escherichia coli and is widely distributed in proteobacteria. The distinguishing feature of sigma32 promoters is a long -10 region (CCCCATNT) whose tetra-C motif is important for promoter activity. Using alanine-scanning mutagenesis of sigma32 and in vivo and in vitro assays, we identified promoter recognition determinants of this motif. The most downstream C (-13) is part of the -10 motif; our work confirms and extends recognition determinants of -13C. Most importantly, our work suggests that the two upstream Cs (-16, -15) constitute an 'extended -10' recognition motif that is recognized by K130, a residue universally conserved in beta- and gamma-proteobacteria. This residue is located in the alpha-helix of sigmaDomain 3 that mediates recognition of the extended -10 promoter motif in other sigmas. K130 is not conserved in alpha- and delta-/epsilon-proteobacteria and we found that sigma32 from the alpha-proteobacterium Caulobacter crescentus does not need the extended -10 motif for high promoter activity. This result supports the idea that K130 mediates extended -10 recognition. Sigma32 is the first Group 3 sigma shown to use the 'extended -10' recognition motif. PMID:19400791

  5. Structural and functional characterization of the oxidoreductase alpha-DsbA1 from Wolbachia pipientis.

    Science.gov (United States)

    Kurz, Mareike; Iturbe-Ormaetxe, Iñaki; Jarrott, Russell; Shouldice, Stephen R; Wouters, Merridee A; Frei, Patrick; Glockshuber, Rudi; O'Neill, Scott L; Heras, Begoña; Martin, Jennifer L

    2009-07-01

    The alpha-proteobacterium Wolbachia pipientis is a highly successful intracellular endosymbiont of invertebrates that manipulates its host's reproductive biology to facilitate its own maternal transmission. The fastidious nature of Wolbachia and the lack of genetic transformation have hampered analysis of the molecular basis of these manipulations. Structure determination of key Wolbachia proteins will enable the development of inhibitors for chemical genetics studies. Wolbachia encodes a homologue (alpha-DsbA1) of the Escherichia coli dithiol oxidase enzyme EcDsbA, essential for the oxidative folding of many exported proteins. We found that the active-site cysteine pair of Wolbachia alpha-DsbA1 has the most reducing redox potential of any characterized DsbA. In addition, Wolbachia alpha-DsbA1 possesses a second disulfide that is highly conserved in alpha-proteobacterial DsbAs but not in other DsbAs. The alpha-DsbA1 structure lacks the characteristic hydrophobic features of EcDsbA, and the protein neither complements EcDsbA deletion mutants in E. coli nor interacts with EcDsbB, the redox partner of EcDsbA. The surface characteristics and redox profile of alpha-DsbA1 indicate that it probably plays a specialized oxidative folding role with a narrow substrate specificity. This first report of a Wolbachia protein structure provides the basis for future chemical genetics studies. PMID:19265485

  6. Detection of S-nitrosothiol and nitrosylated proteins in Arachis hypogaea functional nodule: response of the nitrogen fixing symbiont.

    Directory of Open Access Journals (Sweden)

    Debasis Maiti

    Full Text Available To detect the presence of NO, ROS and RNS in nodules of crack entry legumes, we used Arachis hypogaea functional nodule. The response of two cognate partner rhizobia was compared towards NO and GSNO using S. meliloti and Bradyrhizobium sp NC921001. ROS, NO, nitrosothiol and bacteroids were detected by fluorescence microscopy. Redox enzymes and thiol pools were detected biochemically. Nitrosothiols were found to be present but ROS and NO were absent in A. hypogaea nodule. A number of S-nitrosylated proteins were also detected. The total thiol pool and most of the redox enzymes were low in nodule cytosolic extract but these were found to be high in the partner microorganisms indicating partner rhizobia could protect the nodule environment against the nitrosothiols. Both S. meliloti and Bradyrhizobium sp NC921001 were found to contain GSNO reductase. Interestingly, there was a marked difference in growth pattern between S. meliloti and Bradyrhizobium sp in presence of sodium nitroprusside (SNP and S-nitrosoglutathione (GSNO. Bradyrhizobium sp was found to be much more tolerant to NO donor compounds than the S. meliloti. In contrast, S. meliloti showed resistance to GSNO but was sensitive to SNP. Together our data indicate that nodule environment of crack entry legumes is different than the nodules of infection mode entry in terms of NO, ROS and RNS. Based on our biochemical characterization, we propose that exchange of redox molecules and reactive chemical species is possible between the bacteroid and nodule compartment.

  7. AcEST: DK953481 [AcEST

    Lifescience Database Archive (English)

    Full Text Available TST39A01NGRL0017_O03 512 Adiantum capillus-veneris mRNA. clone: TST39A01NGRL0017_O03. 5' end seq ... n sp|A6UM48|CH605_SINMW 60 kDa chaperonin 5 OS=Sinorhizobium ... medicae (strain WSM419) Align length 153 Score (bi ... e sp|A6UM48|CH605_SINMW 60 kDa chaperonin 5 OS=Sinorhizobium ... medic... 211 2e-54 sp|P30779|CH60_AGRT5 60 kDa cha ...

  8. Rhizobium nodM and nodN genes are common nod genes: nodM encodes functions for efficiency of nod signal production and bacteroid maturation.

    OpenAIRE

    Baev, N; Schultze, M; Barlier, I; Ha, D C; Virelizier, H.; Kondorosi, E.; Kondorosi, A

    1992-01-01

    Earlier, we showed that Rhizobium meliloti nodM codes for glucosamine synthase and that nodM and nodN mutants produce strongly reduced root hair deformation activity and display delayed nodulation of Medicago sativa (Baev et al., Mol. Gen. Genet. 228:113-124, 1991). Here, we demonstrate that nodM and nodN genes from Rhizobium leguminosarum biovar viciae restore the root hair deformation activity of exudates of the corresponding R. meliloti mutant strains. Partial restoration of the nodulation...

  9. Biological nitrogen fixation by lucerne (Medicago sativa L.) in acid soils.

    OpenAIRE

    Pijnenborg, J.W.M.

    1990-01-01

    Growth of lucerne( Medicago sativa L.) is poor in soils with values of pH-H2O below 6. This is often due to nitrogen deficiency, resulting from a hampered performance of the symbiosis withRhizobium meliloti. This thesis deals with the factors affecting biological nitrogen fixation by lucerne in acid soils.In a field experiment, lucerne seeds were either inoculated withR.meliloti only,or inoculated and pelleted with lime, before sowing in a sandy soil of pH 5.2. Lime-pelleting significantly im...

  10. In vitro replication of mitochondrial plasmid mp1 from the higher plant Chenopodium album (L.): a remnant of bacterial rolling circle and conjugative plasmids?

    Science.gov (United States)

    Backert, S; Kunnimalaiyaan, M; Börner, T; Nielsen, B L

    1998-12-11

    According to the endosymbiotic theory, mitochondrial genomes evolved from the chromosome of an alpha-proteobacterium-like ancestor and developed during evolution an extraordinary variation in size, structure and replication. We studied in vitro DNA replication of the mitochondrial circular plasmid mp1 (1309 bp) from the higher plant Chenopodium album (L.) as a model system that replicates in a manner reminiscent of bacterial rolling circle plasmids. Several mp1 subclones were tested for their ability to support DNA replication using a newly developed in vitro system. Neutral/neutral two-dimensional gel electrophoresis of the in vitro products revealed typical simple Y patterns of intermediates consistent with a rolling circle type of replication. Replication activity was very high for a BamHI-restricted total plasmid DNA clone, a 464 bp BamHI/KpnI fragment and a 363 bp BamHI/SmaI fragment. Further subcloning of a 148 bp BamHI/EcoRI fragment resulted in the strongest in vitro DNA replication activity, while a 1161 bp-template outside of this region resulted in a substantial loss of activity. Electron microscopic studies of in vitro DNA replication products from the highly active clones also revealed sigma-shaped molecules. These results support our in vivo data for the presence of a predominant replication origin between positions 628 and 776 on the plasmid map. This sequence shares homology with double-stranded rolling circle origin (dso) or transfer origin (oriT) nicking motifs from bacterial plasmids. mp1 is the first described rolling circle plasmid in eukaryotes. PMID:9837722

  11. Population Structures of 'Candidatus Liberibacter asiaticus' in Southern China.

    Science.gov (United States)

    Ma, W; Liang, M; Guan, L; Xu, M; Wen, X; Deng, X; Chen, J

    2014-02-01

    Huanglongbing (HLB) is a highly detrimental citrus disease associated with 'Candidatus Liberibacter asiaticus', a nonculturable alpha-proteobacterium. Characterization of the bacterial populations is important for development of disease management strategies. In this study, the 'Ca. L. asiaticus' populations in eight provinces in southern China where HLB is endemic were analyzed based on tandem repeat number (TRN) variations in a previously characterized genomic locus CLIBASIA_01645. Of the 224 HLB samples collected, 175 (78.3%) samples yielded single polymerase chain reaction (PCR) amplicons (the single amplicon group, SAG) and 49 (21.7%) samples produced multiple PCR amplicons (the multiple amplicon group, MAG). Variations in SAG are summarized by Nei's diversity index (H) and ratio of TRN ≤ 10/TRN > 10 genotypes (R10). Variations in the MAG are described by the percentage of occurrence (PMAG). At an orchard-level comparison, the 'Ca. L. asiaticus' population from a Guangdong orchard (n = 24) showed H = 0.50, R10 = 23, and PMAG = 0, significantly different from that of the non-Guangdong orchards in Yunnan (n = 23), H = 0.83, R10 = 2.3, and PMAG = 11.5, and in Hainan (n = 35), H = 0.88, R10 = 1.5, and PMAG = 16.7. In a region-level consideration, the Guangdong 'Ca. L. asiaticus' population (n = 78) was H = 0.77, R10 = 25, and PMAG = 1.3, whereas the non-Guangdong population (n = 84) was H = 0.91, R10 = 1.6, and PMAG = 26.9. Overall, significant differences were observed between the 'Ca. L. asiaticus' population from Guangdong Province and those from the other provinces. A strong aggregation of TRN = 6, 7, and 8 genotypes is characteristic to the 'Ca. L. asiaticus' population in Guangdong. Referenced to genome annotation, we propose that rearrangement of tandem repeats at locus CLIBASIA_01645 could be associated with bacterial environmental adaptation. PMID:24093922

  12. The complete genome sequence of 'Candidatus Liberibacter solanacearum', the bacterium associated with potato zebra chip disease.

    Directory of Open Access Journals (Sweden)

    Hong Lin

    Full Text Available Zebra Chip (ZC is an emerging plant disease that causes aboveground decline of potato shoots and generally results in unusable tubers. This disease has led to multi-million dollar losses for growers in the central and western United States over the past decade and impacts the livelihood of potato farmers in Mexico and New Zealand. ZC is associated with 'Candidatus Liberibacter solanacearum', a fastidious alpha-proteobacterium that is transmitted by a phloem-feeding psyllid vector, Bactericera cockerelli Sulc. Research on this disease has been hampered by a lack of robust culture methods and paucity of genome sequence information for 'Ca. L. solanacearum'. Here we present the sequence of the 1.26 Mbp metagenome of 'Ca. L. solanacearum', based on DNA isolated from potato psyllids. The coding inventory of the 'Ca. L. solanacearum' genome was analyzed and compared to related Rhizobiaceae to better understand 'Ca. L. solanacearum' physiology and identify potential targets to develop improved treatment strategies. This analysis revealed a number of unique transporters and pathways, all potentially contributing to ZC pathogenesis. Some of these factors may have been acquired through horizontal gene transfer. Taxonomically, 'Ca. L. solanacearum' is related to 'Ca. L. asiaticus', a suspected causative agent of citrus huanglongbing, yet many genome rearrangements and several gene gains/losses are evident when comparing these two Liberibacter. species. Relative to 'Ca. L. asiaticus', 'Ca. L. solanacearum' probably has reduced capacity for nucleic acid modification, increased amino acid and vitamin biosynthesis functionalities, and gained a high-affinity iron transport system characteristic of several pathogenic microbes.

  13. Phase Preference by Active, Acetate-Utilizing Bacteria at the Rifle, CO Integrated Field Research Challenge Site

    Energy Technology Data Exchange (ETDEWEB)

    Kerkhoff, Lee; Williams, Kenneth H.; Long, Philip E.; McGuinness, L.

    2011-02-15

    Uranium contaminated groundwaters are a legacy concern for the U.S. Department of Energy. Previous experiments at the Rifle, Colorado Integrated Field Challenge (IFC) site have demonstrated that field-scale addition of acetate to groundwater reduces the ambient soluable uranium concentration, sequestering the radionuclide as uraninite. However, questions remain regarding which microorganism(s) are consuming this acetate and if active groundwater microorganisms are different from active particle-associated bacteria. In this report, 13-C acetate was used to assess the active microbes that synthesize DNA on 3 size fractions [coarse sand, fines (8-approximately 150 micron), groundwater (0.2-8 micron)] over a 24 -day time frame. Results indicated a stronger signal from 13-C acetate associated with the “fines” fraction compared with smaller amounts of 13-C uptake on the sand fraction and groundwater samples during the SIP incubations. TRFLP analysis of this 13-C-labeled DNA, indicated 31+ 9 OTU's with 6 peaks dominating the active profiles (166, 187, 210, 212, and 277 bp peaks using MnlI). Cloning/sequencing of the amplification products indicated a Geobacter-like group (187, 210, 212 bp) primarily synthesized DNA from acetate in the groundwater phase, an alpha Proteobacterium (166 bp) primarily grew on the fines/sands, and an Acinetobacter sp. (277 bp) utilized much of the 13C acetate in both groundwater and particle-associated phases. These findings will help to delineate the acetate utilization patterns of bacteria during field-scale acetate addition and can lead to improved methods for stimulating distinct microbial populations in situ.

  14. Screening a wide host-range, waste-water metagenomic library in tryptophan auxotrophs of Rhizobium leguminosarum and of Escherichia coli reveals different classes of cloned trp genes.

    Science.gov (United States)

    Li, Youguo; Wexler, Margaret; Richardson, David J; Bond, Philip L; Johnston, Andrew W B

    2005-12-01

    A metagenomic cosmid library was constructed, in which the insert DNA was derived from bacteria in a waste-water treatment plant and the vector was the wide host-range cosmid pLAFR3. The library was screened for clones that could correct defined tryptophan auxotrophs of the alpha-proteobacterium Rhizobium leguminosarum and of Escherichia coli. A total of 26 different cosmids that corrected at least one trp mutant in one or both of these species were obtained. Several cosmids corrected the auxotrophy of one or more R. leguminosarum trp mutants, but not the corresponding mutants in E. coli. Conversely, one cosmid corrected trpA, B, C, D and E mutants of E. coli but none of the trp mutants of R. leguminosarum. Two of the Trp+ cosmids were examined in more detail. One contained a trp operon that resembled that of the pathogen Chlamydophila caviae, containing the unusual kynU gene, which specifies kynureninase. The other, whose trp genes functioned in R. leguminosarum but not in E. coli, contained trpDCFBA in an operon that is likely co-transcribed with five other genes, most of which had no known link with tryptophan synthesis. The sequences of these TRP proteins, and the products of nine other genes encoded by this cosmid, failed to affiliate them with any known bacterial lineage. For one metagenomic cosmid, lac reporter fusions confirmed that its cloned trp genes were transcribed in R. leguminosarum, but not in E. coli. Thus, rhizobia, with their many sigma-factors, may be well-suited hosts for metagenomic libraries, cloned in wide host-range vectors. PMID:16309391

  15. Molecular characterization of a mosaic locus in the genome of 'Candidatus Liberibacter asiaticus'

    Directory of Open Access Journals (Sweden)

    Wang Xuefeng

    2012-01-01

    Full Text Available Abstract Background Huanglongbing (HLB is a highly destructive disease of citrus production worldwide. 'Candidatus Liberibacter asiaticus', an unculturable alpha proteobacterium, is a putative pathogen of HLB. Information about the biology and strain diversity of 'Ca. L. asiaticus' is currently limited, inhibiting the scope of HLB research and control. Results A genomic region (CLIBASIA_05640 to CLIBASIA_05650 of 'Ca. L. asiaticus' showing hyper-sequence variation or locus mosaicism was identified and investigated using 262 bacterial strains (188 from China and 74 from Florida. Based on the characteristic electrophoretic profiles of PCR amplicons generated by a specific primer set, eight electrophoretic types (E-types were identified, six E-types (A, B, C, D, E, and F in China and four E-types (A, C, G, and H in Florida. The 'Ca. L. asiaticus' strains from China consisted predominately of E-type A (71.3% and E-type B (19.7%. In contrast, the 'Ca. L. asiaticus' strains from Florida was predominated by E-type G (82.4%. Diversity of 'Ca. L. asiaticus' in China was also evidenced. Strains from the high altitude Yunnan Province consisted of five E-types with E-type B being the majority (62.8%, whereas strains from the low altitude coastal Guangdong Province consisted of only two E-types with E-type A as the majority (97.0%. Sequence analyses revealed that variation of DNA amplicons was due to insertion/deletion events at CLIBASIA_05650 and the downstream intergenic region. Conclusions This study demonstrated the genomic mosaicism of 'Ca. L. asiaticus' resulted from active DNA insertion/deletion activities. Analyses of strain variation depicted the significant inter- and intra-continent diversity of 'Ca. L. asiaticus'.

  16. Dicty_cDB: Contig-U16333-1 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available _1347( CP000739 |pid:none) Sinorhizobium medicae WSM419 pl... 41 0.19 CP000099_1867( CP000099 |pid:none) Methanosarcina...cluding cell wall 4.0 %: vacuolar >> prediction for Contig-U...kvansffldlqicitvqvvgnlpcvglspylggqvpnavwvellipfsdlqvypnalis sitfqtqvqdhqgvffigdisagnfvppykvledgsna...fkllsniyllllifiisllfi* tkkkqinkkhiylyyff*lkk Translated Amino Acid sequence (All Frames) Frame...lgykviipfskititpsttktf ngilitgasnefydliymddlyfsngtvcmeesseypyyqlgqllngasdqyntgnvnfk svsklfrgfptieyqlynnykaii

  17. Interaction of arbuscular mycorrhizal fungi and rhizobia: Effects on flax yield in spoil-bank clay

    Czech Academy of Sciences Publication Activity Database

    Rydlová, Jana; Püschel, David; Sudová, Radka; Gryndler, M.; Mikanová, O.; Vosátka, Miroslav

    2011-01-01

    Roč. 174, č. 1 (2011), s. 128-134. ISSN 1436-8730 R&D Projects: GA MŠk 1M0571 Institutional research plan: CEZ:AV0Z60050516 Keywords : Linum usitatissimum * Glomus * Sinorhizobium Subject RIV: EF - Botanics Impact factor: 1.596, year: 2011

  18. Biological nitrogen fixation by lucerne (Medicago sativa L.) in acid soils.

    NARCIS (Netherlands)

    Pijnenborg, J.W.M.

    1990-01-01

    Growth of lucerne( Medicago sativa L.) is poor in soils with values of pH-H2O below 6. This is often due to nitrogen deficiency, resulting from a hampered performance of the symbiosis withRhizobium meliloti. This thesis deals with the factors affecting biological nitrogen fixat

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

    OpenAIRE

    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. Comparative study of the fungicide Benomyl toxicity on some plant growth promoting bacteria and some fungi in pure cultures

    Directory of Open Access Journals (Sweden)

    Elslahi Randa H.

    2014-03-01

    Full Text Available Six laboratory experiments were carried out to investigate the effect of the fungicide Benomyl on pure cultures of some plant growth promoting bacteria (PGPB and some fungi. The highest LD50 was recorded for Bacillus circulans and proved to be the most resistant to the fungicide, followed by Azospirillum braziliense, while Penicillium sp. was the most affected microorganism. LD50 values for the affected microorganisms were in 21-240 orders of magnitude lower in comparison with the LD50 value for Azospirillum braziliense. The results indicate a strong selectivity for Benomyl against Rhizobium meliloti and Penicillium sp. when compared to other microorganisms tested. The highest safety coefficient was recorded for Bacillus circulans followed by Azospirillum braziliense, while Rhizobium meliloti, showed the lowest safety coefficient value compared to other bacteria. The lowest toxicity index was recorded for Bacillus circulans and Azospirillum braziliense. The slope of the curves for Bacillus sp. and Rhizobium meliloti was steeper than that of the other curves, suggesting that even a slight increase of the dose of the fungicide can cause a very strong negative effect. In conclusion, Benomyl could be applied without restriction when using inocula based on growth promoting bacteria such as symbiotic nitrogen fixers (Rhizobium meliloti, non-symbiotic nitrogen fixers (Azospirillum braziliense or potassium solibilizers (Bacillus circulans, given that the fungicide is applied within the range of the recommended field dose.

  1. Comparative study of the fungicide Benomyl toxicity on some plant growth promoting bacteria and some fungi in pure cultures.

    Science.gov (United States)

    Elslahi, Randa H; Osman, Awad G; Sherif, Ashraf M; Elhussein, Adil A

    2014-03-01

    Six laboratory experiments were carried out to investigate the effect of the fungicide Benomyl on pure cultures of some plant growth promoting bacteria (PGPB) and some fungi. The highest LD50 was recorded for Bacillus circulans and proved to be the most resistant to the fungicide, followed by Azospirillum braziliense, while Penicillium sp. was the most affected microorganism. LD50 values for the affected microorganisms were in 21-240 orders of magnitude lower in comparison with the LD50 value for Azospirillum braziliense. The results indicate a strong selectivity for Benomyl against Rhizobium meliloti and Penicillium sp. when compared to other microorganisms tested. The highest safety coefficient was recorded for Bacillus circulans followed by Azospirillum braziliense, while Rhizobium meliloti, showed the lowest safety coefficient value compared to other bacteria. The lowest toxicity index was recorded for Bacillus circulans and Azospirillum braziliense. The slope of the curves for Bacillus sp. and Rhizobium meliloti was steeper than that of the other curves, suggesting that even a slight increase of the dose of the fungicide can cause a very strong negative effect. In conclusion, Benomyl could be applied without restriction when using inocula based on growth promoting bacteria such as symbiotic nitrogen fixers (Rhizobium meliloti), non-symbiotic nitrogen fixers (Azospirillum braziliense) or potassium solibilizers (Bacillus circulans), given that the fungicide is applied within the range of the recommended field dose. PMID:26038670

  2. Dicty_cDB: Contig-U02029-1 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available 39_1935( CP000539 |pid:none) Acidovorax sp. JS42, complete g... 50 2e-04 CP000738_2958( CP000738 |pid:none) Sinorhizobium med...trongyloides ratti whole genome... 60 1e-05 2 ( FC809434 ) Sr_pASP6_01a11_SP6 S. ratti mixed stage pAMP Stro...USDA 1... 37 0.95 CP000739_394( CP000739 |pid:none) Sinorhizobium medicae WSM419 pla... 37 0.95 CP000472_317... TATTTCC Gap gap included Contig length 1097 Chromosome number (1..6, M) 4 Chromosome length 5430582 Start p...belii BAC clone CH276-246K6 from chromosom... 42 9e-04 7 ( ES272476 ) BGBV-aac54c01.b1 Snail_EST_pSMART Biom

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

    OpenAIRE

    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...

  4. Characterization of Rhizobial Isolates of Phaseolus vulgaris by Staircase Electrophoresis of Low-Molecular-Weight RNA

    OpenAIRE

    Velázquez, Encarna; Martínez-Romero, Esperanza; Rodríguez-Navarro, Dulce Nombre; Trujillo, Martha E.; Daza, Antonio; Mateos, Pedro F.; Martínez-Molina, Eustoquio; van Berkum, Peter

    2001-01-01

    Low-molecular-weight (LMW) RNA molecules were analyzed to characterize rhizobial isolates that nodulate the common bean growing in Spain. Since LMW RNA profiles, determined by staircase electrophoresis, varied across the rhizobial species nodulating beans, we demonstrated that bean isolates recovered from Spanish soils presumptively could be characterized as Rhizobium etli, Rhizobium gallicum, Rhizobium giardinii, Rhizobium leguminosarum bv. viciae and bv. trifolii, and Sinorhizobium fredii.

  5. The effect of inoculation of an indigenous bacteria on the early growth of Acacia farnesiana in a degraded area

    OpenAIRE

    Eliane Ceccon; Anayeli Almazo-Rogel; Esperanza Martínez-Romero; Ivonne Toledo

    2012-01-01

    Restoration of native vegetation and fuelwood production are important environmental pending goals for Mexico, where years of wrong management practices resulted in ecosystemic degradation and fuelwood scarcity. In degraded areas, native rhizobial strains are often undetectable, therefore, the restoration of natural vegetation associated with an effective nodulation of the leguminous trees is mostly appropriate. Sinorhizobium americanum is a native nitrogen-fixing bacteria isolated from nodul...

  6. Identification of a bacteria-like ferrochelatase in Strongyloides venezuelensis, an animal parasitic nematode.

    Directory of Open Access Journals (Sweden)

    Eiji Nagayasu

    Full Text Available Heme is an essential molecule for vast majority of organisms serving as a prosthetic group for various hemoproteins. Although most organisms synthesize heme from 5-aminolevulinic acid through a conserved heme biosynthetic pathway composed of seven consecutive enzymatic reactions, nematodes are known to be natural heme auxotrophs. The completely sequenced Caenorhabditis elegans genome, for example, lacks all seven genes for heme biosynthesis. However, genome/transcriptome sequencing of Strongyloides venezuelensis, an important model nematode species for studying human strongyloidiasis, indicated the presence of a gene for ferrochelatase (FeCH, which catalyzes the terminal step of heme biosynthesis, whereas the other six heme biosynthesis genes are apparently missing. Phylogenetic analyses indicated that nematode FeCH genes, including that of S. venezuelensis (SvFeCH have a fundamentally different evolutionally origin from the FeCH genes of non-nematode metazoa. Although all non-nematode metazoan FeCH genes appear to be inherited vertically from an ancestral opisthokont, nematode FeCH may have been acquired from an alpha-proteobacterium, horizontally. The identified SvFeCH sequence was found to function as FeCH as expected based on both in vitro chelatase assays using recombinant SvFeCH and in vivo complementation experiments using an FeCH-deficient strain of Escherichia coli. Messenger RNA expression levels during the S. venezuelensis lifecycle were examined by real-time RT-PCR. SvFeCH mRNA was expressed at all the stages examined with a marked reduction at the infective third-stage larvae. Our study demonstrates the presence of a bacteria-like FeCH gene in the S. venezuelensis genome. It appeared that S. venezuelensis and some other animal parasitic nematodes reacquired the once-lost FeCH gene. Although the underlying evolutionary pressures that necessitated this reacquisition remain to be investigated, it is interesting that the presence of Fe

  7. Greenhouse evaluation of rhizobia as biocontrol agent of root-infecting fungi in okra

    Directory of Open Access Journals (Sweden)

    I. A. Siddiqui

    2013-12-01

    Full Text Available Nine rhizobial strains isolated from the root nodules of Cicer arietinum, Vigna radiata, V. mungo, Samania saman, Sesbania sesban, Leucinia sp., Prosopis cineraria and Medicago sativa were used to study their effects on root-infecting fungi viz., Macrophomina phaseolina, Fusarium solani and Rhizoctonia solani. In dual culture plate assay, strains of Bradyrhizobium sp., and R. meliloti were found to inhibit radial growth of M. phaseolina, F. solani and R. solani producing zones of inhibition. Bradyrhizobium sp., and R. meliloti either used as seed dressing or as soil drench significantly suppressed root-rot infection caused by M. phaseolina, F. solani and R. solani in okra, a non-1eguminous crop under greenhouse conditions. Biomass of plants was also higher in the presence of rhizobia.

  8. AcEST: DK952684 [AcEST

    Lifescience Database Archive (English)

    Full Text Available |Q92R50|Q92R50_RHIME Hypothetical transmembrane protein OS=Rhi... 38 0.27 tr|A6U7A5|A6U7A5_SINMW Putative uncharacterized...92R50_RHIME Hypothetical transmembrane protein OS=Rhizobium meliloti Align length 75 Score (bit) 38.1 E-valu...|Q92R50|Q92R50_RHIME Hypothetical transmembrane protein OS=Rhizobium meliloti GN=R01069 P...p_hit_id Q66AG7 Definition sp|Q66AG7|RNFD_YERPS Electron transport complex protein rnfD OS=Yersinia pseudotu...ences producing significant alignments: (bits) Value sp|Q66AG7|RNFD_YERPS Electron transport complex protein

  9. Greenhouse evaluation of rhizobia as biocontrol agent of root-infecting fungi in okra

    OpenAIRE

    Siddiqui, I. A.; S. Ehteshamul-Haque; Zaki, M. J.; Ghaffar, A.

    2013-01-01

    Nine rhizobial strains isolated from the root nodules of Cicer arietinum, Vigna radiata, V. mungo, Samania saman, Sesbania sesban, Leucinia sp., Prosopis cineraria and Medicago sativa were used to study their effects on root-infecting fungi viz., Macrophomina phaseolina, Fusarium solani and Rhizoctonia solani. In dual culture plate assay, strains of Bradyrhizobium sp., and R. meliloti were found to inhibit radial growth of M. phaseolina, F. solani and R. solani producing zones of inhibition. ...

  10. Denitrification in Rhisobium in sterile soil

    International Nuclear Information System (INIS)

    The process of denitrification has been studied in two strains of root nodule bacteria, R. vigna 164 and R. meliloti 425a, introduced into soil samples sterilized by γ-irradiation. Intensity of denitrification was shown to depend on the type of soil, wetness, introduction of glucose. 57.3-78% of the introduced nitrates have been consumed by R. vigna, and 21.1-29.1 %, by R. melioti by the end of incubation (22 days)

  11. Degradation of the Herbicide Glyphosate by Members of the Family Rhizobiaceae

    OpenAIRE

    Liu, C.-M.; McLean, P A; Sookdeo, C. C.; Cannon, F C

    1991-01-01

    Several strains of the family Rhizobiaceae were tested for their ability to degrade the phosphonate herbicide glyphosate (isopropylamine salt of N-phosphonomethylglycine). All organisms tested (seven Rhizobium meliloti strains, Rhizobium leguminosarum, Rhizobium galega, Rhizobium trifolii, Agrobacterium rhizogenes, and Agrobacterium tumefaciens) were able to grow on glyphosate as the sole source of phosphorus in the presence of the aromatic amino acids, although growth on glyphosate was not a...

  12. Optimization of Dairy Sludge for Growth of Rhizobium Cells

    OpenAIRE

    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...

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

    OpenAIRE

    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.

  14. Reiterated DNA Sequences in Rhizobium and Agrobacterium spp

    OpenAIRE

    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...

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

    OpenAIRE

    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.

  16. Ankara Üniversitesi Ziraat Fakültesi yonca ekim alanlarında görülen önemli hastalıkların belirlenmesi

    OpenAIRE

    KARAKAYA, Aziz; ONAR, Mihrace Çiğdem

    2006-01-01

    In this study, important alfalfa diseases occurring in the Ankara University Faculty of Agriculture Haymana and Ayaş Research Farms and Dışkapı Campus were determined. Samples were collected during the years 2003 and 2004 and causal agents of the diseases were identified. The fungi found were: Phoma medicaginis var. medicaginis, Leptotrochila medicaginis, Leveillula taurica, Pseudopeziza medicaginis, Peronospora trifoliorum, Stemphylium botryosum, Stagonospora meliloti, Colletotrichum trifoli...

  17. Dicty_cDB: Contig-U15884-1 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available P000089 |pid:none) Dechloromonas aromatica RCB, co... 36 3.5 CP000740_763( CP000740 |pid:none) Sinorhizobium med...is vinifera contig VV78X149785.4, whole genome... 46 3.3 1 ( AC147365 ) Medicago ...onas palustris HaA2, complete genome. Length = 174 Score = 98.6 bits (244), Expect = 4e-19 Iden... Contig length 1300 Chromosome number (1..6, M) 4 Chromosome length...... 38 0.29 2 ( DN080300 ) JGI_CABD12377.fwd NIH_XGC_tropLun1 Xenopus (Silur... 38 0.29 2 ( AC208397 ) Macaca mulatta chromosome

  18. Dicty_cDB: Contig-U14075-1 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available nas paucimobilis strain 6... 38 0.13 AE016819_887( AE016819 |pid:none) Ashbya gossypii (= Eremo...3( AF120976 |pid:none) Sphingomonas paucimobilis strain 6... 35 0.62 AM181176_641( AM181176 |pid:none) Pseudomo...M 6... 41 0.015 AF390440_2( AF390440 |pid:none) Pseudomonas putida major facilita...ana ecotype Br-0 ... 35 0.82 AL591985_547( AL591985 |pid:none) Sinorhizobium melil...klmvfqifkltlkikksvvk vqkweqmny*rifkklernvqlllklvivnnnnnlk*ynityiytqflikfqdkmechcs wvq*kkkkktkkqknkklskinlvlleilvli Frame C: nnli

  19. Dicty_cDB: Contig-U13132-1 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available nas mobilis subsp. mobilis... 35 3.0 A70179( A70179 ) exodeo..._1( AF093783 |pid:none) Salmonella typhimurium 2-oxoglutar... 99 3e-19 DQ423340_1( DQ423340 |pid:none) Sinorhizobium melil...Pea aphid whole body normalized full le... 44 1e-04 3 ( FE849223 ) CAFO396.fwd CAFO Pichia stipitis aerobic ... 9e-53 CP000672_326( CP000672 |pid:none) Haemophilus influenzae PittGG, c... 209 ...a DC2201 DNA, c... 209 2e-52 AM942759_562( AM942759 |pid:none) Proteus mirabilis strain HI4320,... 209 2e-5

  20. Detection and organization of atrazine-degrading genetic potential of seventeen bacterial isolates belonging to divergent taxa indicate a recent common origin of their catabolic functions

    DEFF Research Database (Denmark)

    El Azhari, Najoi

    2007-01-01

    conjugation could play an important role in their dispersion. In addition, the observation of these genes (i) on the chromosome, (ii) on the same DNA fragment but on different plasmids and (iii) on DNA fragments also hybridizing with IS1071 suggests that transposition may also contribute to disperse...... the trzN-atzBC gene composition in Gram-negative bacteria such as Sinorhizobium sp. or Polaromonas sp. Three main atrazine-degrading gene combinations (i) trzN–atzBC, (ii) atzABC–trzD and (iii) atzABCDEF were observed. The atz and trz genes were often located on plasmids, suggesting that plasmid...

  1. Variation of clonal, mesquite-associated rhizobial and bradyrhizobial populations from surface and deep soils by symbiotic gene region restriction fragment length polymorphism and plasmid profile analysis.

    Science.gov (United States)

    Thomas, P M; Golly, K F; Zyskind, J W; Virginia, R A

    1994-04-01

    Genetic characteristics of 14 Rhizobium and 9 Bradyrhizobium mesquite (Prosopis glandulosa)-nodulating strains isolated from surface (0- to 0.5-m) and deep (4- to 6-m) rooting zones were determined in order to examine the hypothesis that surface- and deep-soil symbiont populations were related but had become genetically distinct during adaptation to contrasting soil conditions. To examine genetic diversity, Southern blots of PstI-digested genomic DNA were sequentially hybridized with the nodDABC region of Rhizobium meliloti, the Klebsiella pneumoniae nifHDK region encoding nitrogenase structural genes, and the chromosome-localized ndvB region of R. meliloti. Plasmid profile and host plant nodulation assays were also made. Isolates from mesquite nodulated beans and cowpeas but not alfalfa, clover, or soybeans. Mesquite was nodulated by diverse species of symbionts (R. meliloti, Rhizobium leguminosarum bv. phaseoli, and Parasponia bradyrhizobia). There were no differences within the groups of mesquite-associated rhizobia or bradyrhizobia in cross-inoculation response. The ndvB hybridization results showed the greatest genetic diversity among rhizobial strains. The pattern of ndvB-hybridizing fragments suggested that surface and deep strains were clonally related, but groups of related strains from each soil depth could be distinguished. Less variation was found with nifHDK and nodDABC probes. Large plasmids (>1,500 kb) were observed in all rhizobia and some bradyrhizobia. Profiles of plasmids of less than 1,000 kb were related to the soil depth and the genus of the symbiont. We suggest that interacting selection pressures for symbiotic competence and free-living survival, coupled with soil conditions that restrict genetic exchange between surface and deep-soil populations, led to the observed patterns of genetic diversity. PMID:16349226

  2. AcEST: BP914034 [AcEST

    Lifescience Database Archive (English)

    Full Text Available inghui Zhang, Zheng Zhang, Webb Miller, and David J. Lipman (1997), Gapped BLAST and PSI-BLAST: a new genera...Stephen F., Thomas L. Madden, Alejandro A. Schaffer, Jinghui Zhang, Zheng Zhang, Webb Miller, and David J. L...isomerase 1 OS=Rhizobium meliloti Align length 63 Score (bit) 31.6 E-value 1.3 Re...tion of protein database search programs, Nucleic Acids Res. 25:3389-3402. Query= BP914034|Adiantum capillus...s Res. 25:3389-3402. Query= BP914034|Adiantum capillus-veneris mRNA, clone: YMU001_000039_B05. (379 le

  3. AcEST: BP919564 [AcEST

    Lifescience Database Archive (English)

    Full Text Available se B, chloroplastic OS=Sola... 140 2e-33 sp|Q08305|PPOC_SOLLC Polyphenol oxidase ... (Fragme... 50 5e-06 sp|P33180|TYRO_RHIME Tyrosinase OS=Rhizobium meliloti GN=mepA PE... 49 1e-05 sp|P56826|HCYG_SEPO...144 ILAYKYQDVPNGWLNAAPRSRTS 76 + Y Y +P W N P+S+ S Sbjct: 423 KMGYDYAPMPTPWRNFKPKSKAS 445 >sp|Q08305|PPOC_SO...-Prot sp_hit_id P43309 Definition sp|P43309|PPO_MALDO Polyphenol oxidase, chlorop...ing significant alignments: (bits) Value sp|P43309|PPO_MALDO Polyphenol oxidase,

  4. AcEST: DK954734 [AcEST

    Lifescience Database Archive (English)

    Full Text Available TST39A01NGRL0021_D17 605 Adiantum capillus-veneris mRNA. clone: TST39A01NGRL0021_D17. 5' end seq ... astic OS=Spinaci... 119 2e-26 sp|P33180|TYRO_RHIME Tyrosinase ... OS=Rhizobium meliloti GN=mepA PE... 39 0.021 sp|Q0 ... 4604|TYRO_RANNI Tyrosinase ... OS=Rana nigromaculata GN=TYR PE=... 37 0.10 sp|P40 ...

  5. AcEST: DK950755 [AcEST

    Lifescience Database Archive (English)

    Full Text Available TST38A01NGRL0009_I12 701 Adiantum capillus-veneris mRNA. clone: TST38A01NGRL0009_I12. 5' end seq ... roplastic OS=Sola... 91 5e-18 sp|P33180|TYRO_RHIME Tyrosinase ... OS=Rhizobium meliloti GN=mepA PE... 34 0.67 sp|Q9B ... S=Bos taurus PE=2 SV=1 33 1.9 sp|O42713|TYRO_AGABI Tyrosinase ... OS=Agaricus bisporus GN=ppo2 PE=... 32 2.5 sp|Q9BY ...

  6. AcEST: DK954144 [AcEST

    Lifescience Database Archive (English)

    Full Text Available TST39A01NGRL0019_K15 587 Adiantum capillus-veneris mRNA. clone: TST39A01NGRL0019_K15. 5' end seq ... astic OS=Spinaci... 112 1e-24 sp|P33180|TYRO_RHIME Tyrosinase ... OS=Rhizobium meliloti GN=mepA PE... 39 0.019 sp|Q0 ... 4604|TYRO_RANNI Tyrosinase ... OS=Rana nigromaculata GN=TYR PE=... 37 0.095 sp|P4 ...

  7. AcEST: DK962978 [AcEST

    Lifescience Database Archive (English)

    Full Text Available TST39A01NGRL0015_E22 653 Adiantum capillus-veneris mRNA. clone: TST39A01NGRL0015_E22. 5' end seq ... astic OS=Spinaci... 119 2e-26 sp|P33180|TYRO_RHIME Tyrosinase ... OS=Rhizobium meliloti GN=mepA PE... 39 0.023 sp|Q0 ... 4604|TYRO_RANNI Tyrosinase ... OS=Rana nigromaculata GN=TYR PE=... 37 0.11 sp|P40 ...

  8. AcEST: DK954915 [AcEST

    Lifescience Database Archive (English)

    Full Text Available TST39A01NGRL0021_L12 578 Adiantum capillus-veneris mRNA. clone: TST39A01NGRL0021_L12. 5' end seq ... astic OS=Spinaci... 112 1e-24 sp|P33180|TYRO_RHIME Tyrosinase ... OS=Rhizobium meliloti GN=mepA PE... 39 0.019 sp|Q0 ... 4604|TYRO_RANNI Tyrosinase ... OS=Rana nigromaculata GN=TYR PE=... 37 0.093 sp|P4 ...

  9. AcEST: DK961708 [AcEST

    Lifescience Database Archive (English)

    Full Text Available TST39A01NGRL0010_O07 586 Adiantum capillus-veneris mRNA. clone: TST39A01NGRL0010_O07. 5' end seq ... oroplastic OS=Ipo... 79 2e-14 sp|P33180|TYRO_RHIME Tyrosinase ... OS=Rhizobium meliloti GN=mepA PE... 36 0.16 sp|Q04 ... 604|TYRO_RANNI Tyrosinase ... OS=Rana nigromaculata GN=TYR PE=... 35 0.27 sp|P29 ...

  10. AcEST: DK955424 [AcEST

    Lifescience Database Archive (English)

    Full Text Available TST39A01NGRL0023_A24 521 Adiantum capillus-veneris mRNA. clone: TST39A01NGRL0023_A24. 5' end seq ... astic OS=Spinaci... 112 8e-25 sp|P33180|TYRO_RHIME Tyrosinase ... OS=Rhizobium meliloti GN=mepA PE... 39 0.015 sp|Q0 ... 4604|TYRO_RANNI Tyrosinase ... OS=Rana nigromaculata GN=TYR PE=... 37 0.073 sp|P4 ...

  11. AcEST: DK961956 [AcEST

    Lifescience Database Archive (English)

    Full Text Available TST39A01NGRL0011_J02 680 Adiantum capillus-veneris mRNA. clone: TST39A01NGRL0011_J02. 5' end seq ... astic OS=Spinaci... 119 2e-26 sp|P33180|TYRO_RHIME Tyrosinase ... OS=Rhizobium meliloti GN=mepA PE... 39 0.025 sp|Q0 ... 4604|TYRO_RANNI Tyrosinase ... OS=Rana nigromaculata GN=TYR PE=... 37 0.13 sp|P40 ...

  12. Low Earth orbit journey and ground simulations studies point out metabolic changes in the ESA life support organism Rhodospirillum rubrum

    Science.gov (United States)

    Mastroleo, Felice; Leys, Natalie; Benotmane, Rafi; Vanhavere, Filip; Janssen, Ann; Hendrickx, Larissa; Wattiez, Ruddy; Mergeay, Max

    MELiSSA (Micro-Ecological Life Support System Alternative) is a project of closed regenerative life support system for future space flights developed by the European Space Agency. It consists of interconnected processes (i.e. bioreactors, higher plant compartments, filtration units,..) targeting the total recycling of organic waste into oxygen, water and food. Within the MELiSSA loop, the purple non-sulfur alpha-proteobacterium R. rubrum ATCC25903 is used to convert fatty acids released from the upstream raw waste digesting reactor to CO2 and biomass, and to complete the mineralization of aminoacids into NH4+ that will be forwarded to the nitrifying compartment. Among the numerous challenges of the project, the functional stability of the bioreactors in long term and under space flight conditions is of paramount importance for the efficiency of the life support system and consequently the crew safety. Therefore, the physiological and metabolic changes induced by space flight were investigated for R. rubrum. The bacterium grown on solid medium during 2 different 10-day space flights to the ISS (MES- SAGE2, BASE-A experiments) were compared to cells grown on Earth 1 g gravity or modeled microgravity and normal Earth radiation or simulated space flight radiation conditions in order to relate each single stress to its respective cellular response. For simulating the radiation environment, pure gamma and neutron sources were combined, while simulation of changes in gravity where performed using the Random Positioning Machine technology. Transcriptome analysis using R. rubrum total genome DNA-chip showed up-regulation of genes involved in oxidative stress response after a 10-day mission inside the ISS, without loss of viability. As an example, alkyl hydroperoxide reductase, thioredoxin reductase and bacterioferritin genes are least 2 fold induced although the radiation dose experienced by the bacterium (4 mSv) is very low compared to its radiotolerance (D10 = 100 Sv

  13. Biodegradation of geosmin in drinking water by novel bacteria isolated from biologically active carbon

    Institute of Scientific and Technical Information of China (English)

    Beihai Zhou; Rongfang Yuan; Chunhong Shi; Liying Yu; Junnong Gu; Chunlei Zhang

    2011-01-01

    Three strains of Gram-negative bacteria capable of removing geosmin from drinking water were isolated from biologically active carbon and identified to be Chryseobacterium sp., Sinorhizobium sp.and Stenotrophomonas sp.based on physio-biochemistry analysis and 16S rRNA gene sequence analysis.Removal efficiencies of 2 mg/L geosmin in mineral salts medium were 84.0%, 80.2% and 74.4% for Chryseobacterium sp., Sinorhizobium sp.and Stenotrophomonas sp., respectively, while removal efficiencies of 560 ng/L geosmin in filter influent were 84.8%, 82.3% and 82.5%, respectively.The biodegradation of geosmin was determined to be a pseudo first-order reaction, with rate constants at 2 mg/L and 560 ng/L being 0.097 and 0.086 day-1, 0.089 and 0.084 day-1, 0.074 and 0.098 day-1 for the above mentioned degraders, respectively.The biomass of culture in the presence of geosmin was much higher than that in the absence of geosmin.

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

    Directory of Open Access Journals (Sweden)

    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.

  15. CONDITIONING MICROBIAL PRODUCTS CONTAINING NITROGEN FIXING BACTERIA WITH DIFFERENT SOLID EXCIPIENTS

    Directory of Open Access Journals (Sweden)

    VINTILĂ T.

    2007-01-01

    Full Text Available The stability in real time of two strains of Rhizobium (Rhizobium meliloti andRhizobium japonicum mixed with different excipients was evaluated during a6-months period. The excipients studied were: peat, peat and calciumcarbonate, zeolite, and ceramic. Liquid cultures and excipients mixtures weredried (12-14% humidity, sealed in plastic bags and preserved at +4oC. Thecells were activated periodically by suspending aliquots from dry products in0.9% saline solution. The viability of Rhizobium cells was evaluated bycultivation of diluted suspensions in YMA plates. The number of viable cells isdecreasing during drying in all cases, increase in the first month of storage,and remains constant or decrease very slowly during storage for all obtaineddry products containing rhizobia mixed with solid dry excipients. The highestnumber of viable cells at the end of the experiment was obtained in ceramicwith Rhizobium japonicum (8x105 cells/gram, and the lowest number ofviable cells was obtained in zeolite with Rhizobium meliloti (1,1x103cells/gram.

  16. Rhizobial plasmid pLPU83a is able to switch between different transfer machineries depending on its genomic background.

    Science.gov (United States)

    Torres Tejerizo, Gonzalo; Pistorio, Mariano; Althabegoiti, María J; Cervantes, Laura; Wibberg, Daniel; Schlüter, Andreas; Pühler, Alfred; Lagares, Antonio; Romero, David; Brom, Susana

    2014-06-01

    Plasmids have played a major role in bacterial evolution, mainly by their capacity to perform horizontal gene transfer (HGT). Their conjugative transfer (CT) properties are usually described in terms of the plasmid itself. In this work, we analyzed structural and functional aspects of the CT of pLPU83a, an accessory replicon from Rhizobium sp. LPU83, able to transfer from its parental strain, from Ensifer meliloti, or from Rhizobium etli. pLPU83a contains a complete set of transfer genes, featuring a particular organization, shared with only two other rhizobial plasmids. These plasmids contain a TraR quorum-sensing (QS) transcriptional regulator, but lack an acyl-homoserine lactone (AHL) synthase gene. We also determined that the ability of pLPU83a to transfer from R. etli CFN42 genomic background was mainly achieved through mobilization, employing the machinery of the endogenous plasmid pRetCFN42a, falling under control of the QS regulators from pRetCFN42a. In contrast, from its native or from the E. meliloti background, pLPU83a utilized its own machinery for conjugation, requiring the plasmid-encoded traR. Activation of TraR seemed to be AHL independent. The results obtained indicate that the CT phenotype of a plasmid is dictated not only by the genes it carries, but by their interaction with its genomic context. PMID:24646299

  17. Efficacy of wild plant in combination with microbial antagonists for the control of root rot fungi on mungbean and cowpea

    International Nuclear Information System (INIS)

    Present work was carried out to investigate the efficacy of Aerva javanica in combination with different microbial antagonists namely Rhizobium meliloti, Pseudomonas aeruginosa, Trichoderma harzianum and Aspergillus niger. Soil amended with A. javanica stem, leaves, flower powder at the rate1% w/w and seeds of cowpea (Vigna unguiculata L.) and mungbean (Vigna radiata L.) were coated with microbial antagonists for the control of root infecting fungi like Macrophomina phaseolina (Tassi) Goid, Fusarium spp. and Rhizoctonia solani Kiihn. Infection of M. phaseolina and R. solani were completely suppressed when seeds were coated with P. aeruginosa, T. harzianum, A. niger, R. meliloti and A. javanica leaves powder mixed in soil at the rate 1% w/w. All antagonists showed reduction in combination with A. javanica leaves powder at the rate1% but T. harzianum and P. aeruginosa in combination with A. javanica leaves showed promising results in complete reduction of R. solani and M. phaseolina on both crops. All growth parameters were maximum when soil was amended with A. javanica leaves powder at the rate 1% w/w and seeds were coated with T. harzianum and P. aeruginosa. (author)

  18. CONDITIONING MICROBIAL PRODUCTS CONTAINING NITROGEN FIXING BACTERIA WITH DIFFERENT SOLID EXCIPIENTS

    Directory of Open Access Journals (Sweden)

    DANIELA VINTILĂ

    2013-12-01

    Full Text Available The stability in real time of two strains of Rhizobium (Rhizobium meliloti and Rhizobium japonicum mixed with different excipients was evaluated during a 6- months period. The excipients studied were: peat, peat and calcium carbonate, zeolite, and ceramic. Liquid cultures and excipients mixtures were dried (12-14% humidity, sealed in plastic bags and preserved at +4oC. The cells were activated periodically by suspending aliquots from dry products in 0.9% saline solution. The viability of Rhizobium cells was evaluated by cultivation of diluted suspensions in YMA plates. The number of viable cells is decreasing during drying in all cases, increase in the first month of storage, and remains constant or decrease very slowly during storage for all obtained dry products containing rhizobia mixed with solid dry excipients. 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.

  19. Characterization of root-nodulating bacteria associated to Prosopis farcta growing in the arid regions of Tunisia.

    Science.gov (United States)

    Fterich, A; Mahdhi, M; Caviedes, M A; Pajuelo, E; Rivas, R; Rodriguez-Llorente, I D; Mars, M

    2011-06-01

    Diversity of 50 bacterial isolates recovered from root nodules of Prosopis farcta grown in different arid soils in Tunisia, was investigated. Characterization of isolates was assessed using a polyphasic approach including phenotypic characteristics, 16S rRNA gene PCR--RFLP and sequencing, nodA gene sequencing and MLSA. It was found that most of isolates are tolerant to high temperature (40°C) and salinity (3%). Genetic characterization emphasizes that isolates were assigned to the genus Ensifer (80%), Mesorhizobium (4%) and non-nodulating endophytic bacteria (16%). Forty isolates belonging to the genus Ensifer were affiliated to Ensifer meliloti, Ensifer xinjiangense/Ensifer fredii and Ensifer numidicus species. Two isolates belonged to the genus Mesorhizobium. Eight isolates failing to renodulate their host plant were endophytic bacteria and belonged to Bacillus, Paenibacillus and Acinetobacter genera. Symbiotic properties of nodulating isolates showed a diversity in their capacity to infect their host plant and fix atmospheric nitrogen. Isolate PG29 identified as Ensifer meliloti was the most effective one. Ability of Prosopis farcta to establish symbiosis with rhizobial species confers an important advantage for this species to be used in reforestation programs. This study offered the first systematic information about the diversity of microsymbionts nodulating Prosopis farcta in the arid regions of Tunisia. PMID:21359955

  20. STABILITY IN REAL TIME OF SOME CRYOPRESERVED MICROBIAL STRAINS WITH REFERENCE TO GENETICALLY MODIFIED MICROORGANISMS

    Directory of Open Access Journals (Sweden)

    DANIELA VINTILĂ

    2013-12-01

    Full Text Available The aim of this work is to analyze the viability of microorganisms from Collection of Industrial Microorganisms from Faculty of Animal Science and Biotechnology – Timisoara, during freezing and thawing as part of cryopreservation technique. The stability in real time of 19 strains cryopreserved in 16% glycerol was evaluated during a 6-months period. The strains studied were: Escherichia coli, Lactobacillus acidophilus, Rhizobium meliloti, Saccharomyces cerevisiae, Aspergillus oryzae, Aspergillus niger, Trichoderma viride, Bacillus globigii, Bacillus licheniformis, and 9 strains of Bacillus subtilis. The strains cryopreserved at -20oC and -70oC were activated using the fast thawing protocol. A better cell recovery was achieved with the -70oC protocol reaching an average viability for E. coli of 86,3%, comparing with 78,6% in -20oC protocol. The cell recovery percentages for the other strains were: 92,4% for L. acidophilus, 93,9% for A.niger, 89% for A. oryzae, 86,7% for T. viride, 94,2% for R. meliloti, 82,1% for S. cerevisiae, 89,9% for B. licheniformis. Regarding the viability of genetically modified microorganisms, the values shows a good recovering after freezing and thawing, even after 180 days of cryopreservation. With the -20oC protocol lower viability was observed due probably to the formation of eutectic mixtures and recrystalization processes.

  1. Dicty_cDB: Contig-U06580-1 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available um perfringens SM101, c... 67 3e-10 CP000738_1460( CP000738 |pid:none) Sinorhizobium medi...ter sulfurreducens PCA, c... 64 4e-09 CP000569_834( CP000569 |pid:none) Actinobaci...uolar 4.0 %: mitochondrial >> prediction for Contig-U06580-1 is nuc VS (DIR, S) 2 VH (FL, L) 0 VF (F... 8e-14 AP006618_1867( AP006618 |pid:none) Nocardia farcinica IFM 10152 DN... 79 8e-14 CU207366_2334( CU207366 |pid:none) Grame...inhardtii thioredo... 53 7e-06 AE003849_958( AE003849 |pid:none) Xylella fastidio

  2. Dicty_cDB: Contig-U04580-1 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available pid:none) Oligotropha carboxidovorans OM5 ... 77 5e-13 AY838902_1( AY838902 |pid:none) Antrodia camphorata thiored...180_3261( AE017180 |pid:none) Geobacter sulfurreducens PCA, c... 77 7e-13 EU952268_1( EU952268 |pid:none) Ze...23_2736( AE008923 |pid:none) Xanthomonas axonopodis pv. citr... 72 2e-11 EU056813_1( EU056813 |pid:none) Limonium bicolor thiored...: Full=Thioredoxin, mitochondrial; Shor... 62 2e-08 CP001050_1258( CP001050 |pid:none) Neisseria gonorr...BX572593 |pid:none) Rhodopseudomonas palustris CGA00... 82 1e-14 CP000738_3011( CP000738 |pid:none) Sinorhizobium medi

  3. Dicty_cDB: Contig-U06548-1 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available 2e-16 FN357480_26( FN357480 |pid:none) Schistosoma mansoni genome sequen... 89 2e-16 ( P91883 ) RecName: Full=Thiored.... 256 6e-67 AY294226_15( AY294226 |pid:none) Uncultured bacterium cosmid gbiox......plet... 206 5e-52 CP000739_1355( CP000739 |pid:none) Sinorhizobium medicae WSM41...|pid:none) Alkaliphilus metalliredigens QY... 92 2e-17 AP006840_926( AP006840 |pid:none) Symbio... 90 9e-17 CP000607_1301( CP000607 |pid:none) Chlorobium phaeovibrioides DSM ... 90 9e-17 ( Q06830 ) RecName: Full=Peroxired

  4. Tolerância de rizóbios de diferentes procedências ao zinco, cobre e cádmio Tolerance of rhizobia genera from different origins to zinc, copper and cadmium

    Directory of Open Access Journals (Sweden)

    Alexandre Matsuda

    2002-03-01

    Full Text Available Sessenta estirpes/isolados dos gêneros Bradyrhizobium, Rhizobium, Sinorhizobium, Mesorhizobium e Azorhizobium, procedentes de diferentes locais (Mata Atlântica, Amazônia, culturas agrícolas e experimentos com metais pesados e de espécies hospedeiras pertencentes às subfamílias Papilionoideae, Mimosoideae e Caesalpinoideae, foram avaliadas quanto à tolerância a Zn, Cu e Cd em meio YMA modificado pela adição de tampões biológicos (HEPES e MES e suplementados com Cu (0 a 60 mg L-1, Cd (0 a 60 mg L-1 e Zn (0 a 1.000 mg L-1. Mediante padrões de crescimento atribuídos às culturas nas diferentes concentrações dos metais, avaliaram-se as concentrações máximas toleradas e as doses tóxicas destes metais para redução de crescimento em 25% (DT25 e 50% (DT50. Não houve influência da procedência na concentração máxima de metal tolerada. A ordem de sensibilidade aos metais, considerando-se as concentrações máximas toleradas, foi Azorhizobium > Rhizobium = Mesorhizobium = Sinorhizobium > Bradyrhizobium. A DT25 e a DT50 foram úteis para diferenciarem estirpes/isolados de um mesmo gênero, que atingiram a mesma concentração máxima tolerada a Zn, Cu e Cd. A ordem de toxicidade dos metais estudados foi Cu > Cd > Zn.Sixty strains/isolates of the genera Bradyrhizobium, Rhizobium, Sinorhizobium, Mesorhizobium and Azorhizobium, isolated from different hosts (legume subfamilies: Papilionoideae, Mimosoideae and Caesalpinoideae and location (Atlantic Forest, Amazon region, crop plantings and heavy metal experiments, were evaluated for Zn, Cu and Cd tolerance in YMA medium modified by the addition of biological buffers (HEPES and MES and supplemented with Cu (0 to 60 mg L-1, Cd (0 to 60 mg L-1, and Zn (0 to 1,000 mg L-1sulphates. Growth standards were applied to evaluate rhizobia cultures growth at different metal concentrations, allowing evaluation of highest tolerated concentrations of Zn, Cu, and Cd and the toxic doses

  5. Dicty_cDB: Contig-U11777-1 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available |pid:none) Sinorhizobium fredii strain HH103 ... 39 0.30 CP001140_249( CP001140 |pid:none) Desulfurococcus k...76xd03r1.ab1 CHO_OF4 Nicotiana tabacum ge... 40 5.7 2 ( EU275727 ) Dictyostelium fasciculatum strain SH3 mit...-a... 60 2e-07 CR954208_418( CR954208 |pid:none) Ostreococcus tauri strain OTTH05...lum sp. Y04AAS1, co... 52 5e-05 CR954203_513( CR954203 |pid:none) Ostreococcus tauri strain OTTH05... 52 6e-... L.S.2.15,... 35 4.4 CR954207_76( CR954207 |pid:none) Ostreococcus tauri strain OTTH059... 35 5.7 >BC121620_

  6. Dicty_cDB: Contig-U13167-1 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available ase; Short=Pho... 149 9e-35 AE017350_104( AE017350 |pid:none) Cryptococcus neofor...ne) Sinorhizobium medicae WSM419, c... 42 0.021 CP000879_1708( CP000879 |pid:none) Petroto...xima phosphofructokinase... 39 0.10 CP000679_2279( CP000679 |pid:none) Caldicellulosiruptor saccharo...ase. 1059 0.0 1 ( X89039 ) D.discoideum mRNA for 6-phosphofructo-1-kinase. 1059 0.0 1 ( AC116957 ) Dict...ne) Danio rerio phosphofructokinase, m... 161 2e-38 AB303967_1( AB303967 |pid:none) Macaca fascicularis PFKM mRNA for

  7. Dicty_cDB: Contig-U13760-1 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available Contig/Contig-U13760-1Q.Seq.d (1276 letters) Database: nrp_B 3,236,559 sequences; 1,051,180,864 total letters Searchi...51 |pid:none) Rhodobacter sphaeroides KD131 ch... 72 6e-12 CP000264_387( CP000264 |pid:none) Jannaschi.... 54 2e-05 CP000738_2158( CP000738 |pid:none) Sinorhizobium medicae WSM419, c... 45 2e-05 CP000247_4058( CP000247 |pid:none) Esch...bj_A 92,845,959 sequences; 95,242,211,685 total letters Searching................... 27815, comp... 36 0.016 20 ( ER935905 ) D218 Staphylococcus xylosus 00-1747 subtracted li... 52 0.022 2 ( DV358218 ) NABZ987TF Aedes

  8. AcEST: BP912788 [AcEST

    Lifescience Database Archive (English)

    Full Text Available |Q92Q48|Q92Q48_RHIME Putative outer membrane transmembrane pro... 35 2.0 tr|A5A5Y8|A5A5Y8_9POAL Phenylalan...AVDLRH--IEENVKSAVKSCVMTVAKKTLSTNSTGGLHVARFCEKDLL 567 >tr|Q92Q48|Q92Q48_RHIME Putative outer membrane trans...|A6U8K9|A6U8K9_SINMW Surface antigen (D15) OS=Sinorhizobium medicae (strain WSM419) GN=Smed_1138 PE=3 SV=1 ...12788 - Show BP912788 Clone id YMU001_000022_H04 Library YMU01 Length 495 Definition Adiantum capillus-vener...cterized protein OS=Oryza... 35 2.6 tr|A6MZG1|A6MZG1_ORYSI Phenyl ammonia lyase (Fragme

  9. AcEST: BP918269 [AcEST

    Lifescience Database Archive (English)

    Full Text Available |Q92SH0|Q92SH0_RHIME Probable multidrug-efflux system transmem... 35 3.2 tr|A0YJJ8|A0YJJ8_9CYAN Putative uncharacterized...C628_VITVI Putative uncharacterized protein OS=Vitis... 49 1e-04 tr|Q6YNS0|Q6YNS0_PRUAV Putative translation-initia...|Q6Z720|Q6Z720_ORYSJ Putative Eukaryotic translation initiatio... 33 7.0 tr|Q0E4E1|Q0E4E1_ORYSJ Os...|Q6YNS0|Q6YNS0_PRUAV Putative translation-initiation factor 3 subunit OS=Prunus avium PE=2 ...porter, hydrophobe/amphiphile efflux-1 (HAE1) family OS=Sinorhizobium medicae (stra

  10. AcEST: BP917101 [AcEST

    Lifescience Database Archive (English)

    Full Text Available sis cinerea ... 34 4.7 tr|Q7NTE5|Q7NTE5_CHRVO Type-4 fimbrial biogenesis PilV transmemb... 34 4.8 tr|Q062K5|...L+ Sbjct: 664 QIYLVFAFWQWLRGDSW-VPDMLAAILLVIYLV 695 >tr|A6UDY7|A6UDY7_SINMW ABC transporter related OS=Sinorhizobium medicae (stra...T Sbjct: 787 PTELVSSPPMEPPSSSFSLLSQPSSASLE---ENEGGDAMTTDTTVPPASTAPPT 838 >tr|Q7NTE5|Q7NTE5_CHRVO Type-4 fimbrial biogenesis PilV tran...cterized protein OS=Ustil... 36 1.3 tr|A6UDY7|A6UDY7_SINMW ABC transporter related...6.6 sp|P11101|STP2_RAT Nuclear transition protein 2 OS=Rattus norveg... 30 8.5 sp|P08855|ICAL_RABIT Calpasta

  11. AcEST: DK954501 [AcEST

    Lifescience Database Archive (English)

    Full Text Available S=Sinorh... 35 0.43 sp|A2VDJ0|T131L_HUMAN Transmembrane protein 131-like OS=Homo sap... 31 8.1 >sp|P58342|ATCU2_RHIME Copper-trans...461 SSLLEKIQGEGFKLQ 505 S+L ++G G+ ++ Sbjct: 134 SALAAAVKGAGYGIR 148 >sp|A2VDJ0|T131L_HUMAN Transmembrane pr...|B6Y078|B6Y078_ANATH Copper ion binding protein OS=Anaerocellu... 38 0.80 tr|A6X3Z4|A6X3Z4_OCHA4 Heavy metal trans.................done Score E Sequences producing significant alignments: (bits) Value sp|P58342|ATCU2_RHIME Copper-trans...porting P-type ATPase OS=Sinorhizobium medicae (strain WSM419) GN=actP PE=1 SV=1 Length = 827 Scor

  12. Nitrous oxide reductase genes (nosZ) of denitrifying populations in soil and the earthworm gut are phylogenetically similar

    DEFF Research Database (Denmark)

    Horn, Marcus A.; Drake, Harold L.; Schramm, Andreas

    2006-01-01

    :1662-1669, 2003). This hypothesis implies that the denitrifiers in the earthworm gut are not endemic to the gut but rather are regular members of the soil denitrifier population. To test this hypothesis, the denitrifier populations of gut and soil from three different sites were comparatively assessed by sequence...... analysis of nosZ, the gene for the terminal enzyme in denitrification, N2O reductase. A total of 182 and 180 nosZ sequences were retrieved from gut and soil, respectively; coverage of gene libraries was 79 to 100%. Many of the nosZ sequences were heretofore unknown, clustered with known soil......-derived sequences, or were related to N2O reductases of the genera Bradyrhizobium, Brucella, Dechloromonas, Flavobacterium, Pseudomonas, Ralstonia, and Sinorhizobium. Although the numbers of estimators for genotype richness of sequence data from the gut were higher than those of soil, only one gut-derived nosZ...

  13. CARACTERIZACIÓN FENOTÍPICA DE AISLADOS DE RIZOBIOS PROCEDENTES DE LA LEGUMINOSA FORRAJERA Canavalia ensiformis

    Directory of Open Access Journals (Sweden)

    Ionel Hernández Forte

    2012-01-01

    Full Text Available El objetivo del presente trabajo fue caracterizar fenotípicamente aislados de rizobios procedentes de la leguminosa forrajera Canavalia ensiformis. Se caracterizaron doce aislados, cinco posibles miembros del género Rhizobium/ Sinorhizobium, siete posibles integrantes del género Bradyrhizobium y dos cepas comerciales, BR 2001 y BR 2003a. Para la caracterización fenotípica de los aislados bacterianos se estudió su capacidad de utilizar seis fuentes de carbono, la tolerancia a condiciones de acidez y a diferentes niveles de cloruro de sodio (NaCl, la resistencia a seis antibióticos así como su crecimiento en tres temperaturas de incubación. Se determinó además la capacidad de estos aislados de producir polihidroxibutiratos (PHB. Todos los aislados estudiados utilizaron la lactosa, glucosa y manitol como fuentes de carbono. Uno de los aislados de rápido crecimiento resultó el más tolerante a pH 4.5. Los aislados posibles miembros del género Rhizobium/ Sinorhizobium toleraron una mayor concentración de NaCl que los posibles integrantes del género Bradyrhizobium. Tres de los aislados de rápido crecimiento fueron resistentes a los seis antibióticos utilizados. Cuando los aislados fueron incubados a 370C todos, con excepción del el aislado CP3 y la cepa comercial BR 2001, presentaron un crecimiento similar al control. El aislado CP10, de lento crecimiento, tuvo la capacidad de producir las mayores concentraciones de PHB (0.023 g.L-1.

  14. Seleção de bactérias endofíticas de tomateiro como potenciais agentes de biocontrole e de promoção de crescimento Screening of endophytic bacteria isolated from tomato plants as potencial biocontrol agents and growth promotion

    Directory of Open Access Journals (Sweden)

    Patrícia Baston Barretti

    2009-01-01

    Full Text Available Quarenta isolados bacterianos endofíticos de plantas sadias de tomateiro foram avaliados quanto à sua potencialidade como agentes de biocontrole de doenças do tomateiro. Foi realizada, em casa de vegetação, uma seleção massal utilizando-se Pseudomonas syringae pv. tomato e Alternaria solani, como patógenos desafiantes. Com base na média do número de lesões por planta, quatro isolados foram selecionados como potenciais agentes de biocontrole dessas enfermidades fúngica e bacteriana do tomateiro. Esses isolados foram identificados, por meio do sequenciamento do gene 16S do DNA ribossômico, como Acinetobacter johnsonii (UFV-E05, Serratia marcescens (UFV-E13, Sinorhizobium sp. (UFV-E25 e Bacillus megaterium (UFV-E26. Os mesmos isolados selecionados para o biocontrole também foram avaliados quanto à sua capacidade de promover o crescimento em plantas e somente S. marcescens (UFV-E13 proporcionou aumento na altura das plantas.Forty isolates of endophytic bacteria obtained from healthy tomato plants were tested for their potential as biocontrol agents of tomato diseases. A massal screening was performed at greenhouse using Pseudomonas syringae pv. tomato and Alternaria solani as challenging pathogens. Based on the average number of lesions per plant, four isolates were selected as potential agents of biocontrol of these tomato diseases caused by fungi and bacteria. These isolates were identified by 16S ribosomal DNA sequence analysis as Acinetobacter johnsonii (UFV-E05, Serratia marcescens (UFV-E13, Sinorhizobium sp. (UFV-E25 and Bacillus megaterium (UFV-E26. The four endophytes selected for biocontrol were also evaluated for their ability of promoting plant growth and only S. marcescens (UFV-E13 presented increase in the height of the plants.

  15. The effect of inoculation of an indigenous bacteria on the early growth of Acacia farnesiana in a degraded area

    Directory of Open Access Journals (Sweden)

    Eliane Ceccon

    2012-03-01

    Full Text Available Restoration of native vegetation and fuelwood production are important environmental pending goals for Mexico, where years of wrong management practices resulted in ecosystemic degradation and fuelwood scarcity. In degraded areas, native rhizobial strains are often undetectable, therefore, the restoration of natural vegetation associated with an effective nodulation of the leguminous trees is mostly appropriate. Sinorhizobium americanum is a native nitrogen-fixing bacteria isolated from nodules of the native Acacia species in the region. Acacia farnesiana is a multipurpose leguminous shrub from Mexican seasonally dry tropical forests (SDTF. In this study we analyzed the effect of inoculation with S. americanum on A. farnesiana growth in a greenhouse and in a very degraded area and compared with non-inoculated seedlings. In a greenhouse, we measured the biomass dry weight of different parts of the plant, using destructive sampling after 15, 20, 30, 45 and 120 days of growth. We also calculated the relative growth rate (RGR and the resources allocation (root/shoot weight ratio and root length/root dry weight of seedlings. In a degraded area we measured the seedling length and survival and calculated the RGR. In the greenhouse and in the degraded area, the inoculation positively affected the growth of seedlings. However in the greenhouse, the inoculation did not have effect on resource allocation patterns. Therefore, the inoculation with Sinorhizobium americanum could improve the A. farnesiana growth and the re-establishment of important plant-soil interactions in degraded areas, being a recommendable technique for land restoration and the improvement of fuelwood production.

  16. NMR Structure of the hypothetical protein encoded by the YjbJ gene from Escherichia coli

    Energy Technology Data Exchange (ETDEWEB)

    Pineda-Lucena, Antonio; Liao, Jack; Wu, Bin; Yee, Adelinda; Cort, John R.; Kennedy, Michael A.; Edwards, Aled M.; Arrowsmith, Cheryl H.

    2002-06-01

    Here we describe the solution structure of YjbJ (gil418541) as part of a structural proteomics project on the feasibility of the high-throughput generation of samples from Escherichia coli for structural studies. YjbJ is a hypothetical protein from Escherichia coli protein of unknown function. It is conserved, showing significant sequence identity to four predicted prokaryotic proteins, also of unknown function (Figure 1A). These include gil16762921 from Salmonella enterica (S. typhi), gil17938413 from Agrobacterium tumefaciens, gil16265654 from Sinorizhobium meliloti, and gil15599932 from Pseudomona aeruginosa. The structure of YjbJ reveals a new variation of a common motif (four-helix bundle) that could not be predicted from the protein sequence. Although the biochemical function is unknown, the existence of patterns of conserved residues on the protein surface suggest that the fold and function of all these proteins could be similar.

  17. Dicty_cDB: Contig-U12635-1 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available 000830 |pid:none) Dinoroseobacter shibae DFL 12, ... 49 2e-04 CP000264_2667( CP000264 |pid:none) Jannaschi...3( AC026875 |pid:none) Genomic sequence for Arabidopsis ... 191 6e-82 CP000496_490( CP000496 |pid:none) Pichia stipitis CBS 6054 ch... 4e-07 BA000040_1144( BA000040 |pid:none) Bradyrhizobium japonicum USDA 1... 42 5e-07 CP000496_206( CP000496 |pid:none) Pichia... usitatus Ellin6076, ... 55 3e-06 CP000699_3951( CP000699 |pid:none) Sphingomonas wittichii RW1, com... 55 3...zobium meliloti 1021 pla... 43 0.002 CP000700_167( CP000700 |pid:none) Sphingomonas wittichii RW1 plasm...

  18. AcEST: BP912816 [AcEST

    Lifescience Database Archive (English)

    Full Text Available jandro A. Schaffer, Jinghui Zhang, Zheng Zhang, Webb Miller, and David J. Lipman (1997), Gappe...-2008] Reference: Altschul, Stephen F., Thomas L. Madden, Alejandro A. Schaffer, Jinghui Zhang, Zheng Zhang, Webb Mille...ic Acids Res. 25:3389-3402. Query= BP912816|Adiantum capillus-veneris mRNA, clone: YMU001_000023_C01. (492 le... Result : TrEMBL tr_hit_id Q92YW8 Definition tr|Q92YW8|Q92YW8_RHIME ABC transporter, permease OS=Rhizobium meliloti Align le...YMU001_000023_C01 517 Adiantum capillus-veneris mRNA. clone: YMU001_000023_C01. BP9

  19. AcEST: BP913992 [AcEST

    Lifescience Database Archive (English)

    Full Text Available , Stephen F., Thomas L. Madden, Alejandro A. Schaffer, Jinghui Zhang, Zheng Zhang, Webb Miller, and David J.... Jinghui Zhang, Zheng Zhang, Webb Miller, and David J. Lipman (1997), Gapped BLAST and PSI-BLAST: a new gene...Q92QA1 Definition sp|Q92QA1|TPIS1_RHIME Triosephosphate isomerase 1 OS=Rhizobium meliloti Align le...ids Res. 25:3389-3402. Query= BP913992|Adiantum capillus-veneris mRNA, clone: YMU001_000038_F07. (434 le...YMU001_000038_F07 447 Adiantum capillus-veneris mRNA. clone: YMU001_000038_F07. BP9

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

    International Nuclear Information System (INIS)

    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)

  1. Azospirillum IV

    Energy Technology Data Exchange (ETDEWEB)

    Klingmuller, W.

    1988-01-01

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

  2. Azospirillum IV

    International Nuclear Information System (INIS)

    This book's contents include: Advances in the genetics of Azospirillum brasilense Sp7: Use of Tn5 mutagenesis for gene mapping and identification; Characterization of DNA segments adjacent to the nifHDK genes of Azospirillum brasilense by Sp7 Tn5 site-directed mutagenesis; Selection at the chemostat of Azospirillum brasilense Cd N2-fixing at high O2 pressure. Root hair deformation induced on maize and medicago by an Azospirillum transconjugant containing a Rhizobium meliloti nodulation region. Azospirilla are bacteria that live in association with the roots of many grain crops. Since these bacteria bind molecular nitrogen from the air and excrete plant growth substances, interest has focussed on their potential to increase crop yields

  3. Pleiotropic effect of fluoranthene on anthocyanin synthesis and nodulation of Medicago sativa is reversed by the plant flavone luteolin

    Energy Technology Data Exchange (ETDEWEB)

    Wetzel, A.; Parniske, M.; Werner, D. [Univ. of Marburg (Germany)

    1995-05-01

    The symbiosis between leguminous plants and soil bacteria of the genus Rhizobium is of considerable agronominal importance. Recently it has been found, that polycyclic aromatic hydrocarbons (PAHs; e.g. anthracene, phenanthrene, fluoranthene), occurring as ubiquitous environmental contaminants can inhibit nodulation of Medicago sativa. Fluoranthene is one of the dominant PAHs found in urban particulate matter, sewage sludge or beside motorways. Several organisms have been shown to be able to metabolize and mineralize fluoranthene but the uptake of fluoranthene is limited due to low solubility of fluoranthene in water and strong adsorption to humic substances in soil. Rhizobium meliloti cannot degrade fluoranthene. Toxic effects of fluoranthene on bacterial growth have never been observed. In contrast to their rhizobial symbiotic partners, alfalfa plants grown on a solidified fluoranthene-containing medium, exhibited symptoms of toxicity. They showed a dose-responsive decrease in shoot length and, if inoculated with R. meliloti, inhibition of nodule formation. Growth retardation is accompanied by a decrease in anthocyanin pigmentation of shoots, and an atypical accumulation of anthocyanins in roots. Plant flavonoids are known to play a central role in the signal exchange of the Legume-Rhizobium symbiosis. Phenylpropane derived compounds and flavonoids have been implicated in nodule development. Since fluoranthene impairs nodulation and induces the production of anthocyanins, it is possible that these events are causally linked via phenylpropanoid metabolism. These experiments attempt to overcome the inhibitory effects of fluoranthene by exogeneous application of the flavonoid luteolin. This paper demonstrates that luteolin antagonizes the fluoranthene mediated inhibition of nodule formation and prevents the accumulation of anthocyanins in roots. 29 refs., 4 figs., 1 tab.

  4. Rhizobium leguminosarum symbiovar trifolii, Ensifer numidicus and Mesorhizobium amorphae symbiovar ciceri (or Mesorhizobium loti) are new endosymbiotic bacteria of Lens culinaris Medik.

    Science.gov (United States)

    Sami, Dhaoui; Mokhtar, Rejili; Peter, Mergaert; Mohamed, Mars

    2016-08-01

    A total of 142 rhizobial bacteria were isolated from root nodules of Lens culinaris Medik endemic to Tunisia and they belonged to the species Rhizobium leguminosarum, and for the first time to Ensifer and Mesorhizobium, genera never previously described as microsymbionts of lentil. Phenotypically, our results indicate that L. culinaris Medik strains showed heterogenic responses to the different phenotypic features and they effectively nodulated their original host. Based on the concatenation of the 16S rRNA with relevant housekeeping genes (glnA, recA, dnaK), rhizobia that nodulate lentil belonged almost exclusively to the known R. leguminosarum sv. viciae. Interestingly, R. leguminosarum sv. trifolii, Ensifer numidicus (10 isolates) and Mesorhizobium amorphae (or M. loti) (9 isolates) isolates species, not considered, up to now, as a natural symbiont of lentil are reported. The E. numidicus and M. amorphae (or M. loti) strains induced fixing nodules on Medicago sativa and Cicer arietinum host plants, respectively. Symbiotic gene phylogenies showed that the E. numidicus, new symbiont of lentil, markedly diverged from strains of R. leguminosarum, the usual symbionts of lentil, and converged to the symbiovar meliloti so far described within E. meliloti Indeed, the nodC and nodA genes from the M. amorphae showed more than 99% similarity with respect to those from M. mediterraneum, the common chickpea nodulating species, and would be included in the new infrasubspecific division named M. amorphae symbiovar ciceri, or to M. loti, related to the strains able to effectively nodulate C. arietinum host plant. On the basis of these data, R. leguminosarum sv. trifolii (type strain LBg3 (T)), M. loti or M. amorphae sv. ciceri (type strain LB4 (T)) and E. numidicus (type strain LBi2 (T)) are proposed as new symbionts of L. culinaris Medik. PMID:27267929

  5. Bacterial diversity analysis of Huanglongbing pathogen-infected citrus, using PhyloChip and 16S rRNA gene clone library sequencing

    Energy Technology Data Exchange (ETDEWEB)

    Shankar Sagaram, U.; DeAngelis, K.M.; Trivedi, P.; Andersen, G.L.; Lu, S.-E.; Wang, N.

    2009-03-01

    The bacterial diversity associated with citrus leaf midribs was characterized 1 from citrus groves that contained the Huanglongbing (HLB) pathogen, which has yet to be cultivated in vitro. We employed a combination of high-density phylogenetic 16S rDNA microarray and 16S rDNA clone library sequencing to determine the microbial community composition of symptomatic and asymptomatic citrus midribs. Our results revealed that citrus leaf midribs can support a diversity of microbes. PhyloChip analysis indicated that 47 orders of bacteria from 15 phyla were present in the citrus leaf midribs while 20 orders from phyla were observed with the cloning and sequencing method. PhyloChip arrays indicated that nine taxa were significantly more abundant in symptomatic midribs compared to asymptomatic midribs. Candidatus Liberibacter asiaticus (Las) was detected at a very low level in asymptomatic plants, but was over 200 times more abundant in symptomatic plants. The PhyloChip analysis was further verified by sequencing 16S rDNA clone libraries, which indicated the dominance of Las in symptomatic leaves. These data implicate Las as the pathogen responsible for HLB disease. Citrus is the most important commercial fruit crop in Florida. In recent years, citrus Huanglongbing (HLB), also called citrus greening, has severely affected Florida's citrus production and hence has drawn an enormous amount of attention. HLB is one of the most devastating diseases of citrus (6,13), characterized by blotchy mottling with green islands on leaves, as well as stunting, fruit decline, and small, lopsided fruits with poor coloration. The disease tends to be associated with a phloem-limited fastidious {alpha}-proteobacterium given a provisional Candidatus status (Candidatus Liberobacter spp. later changed to Candidatus Liberibacter spp.) in nomenclature (18,25,34). Previous studies indicate that HLB infection causes disorder in the phloem and severely impairs the translocation of assimilates in

  6. Effects of biotic and abiotic constraints on the symbiosis between rhizobia and the tropical leguminous trees Acacia and Prosopis.

    Science.gov (United States)

    Räsänen, Leena A; Lindström, Kristina

    2003-10-01

    N2-fixing, drought tolerant and multipurpose Acacia and Prosopis species are appropriate trees for reforestation of degraded areas in arid and semiarid regions of the tropics and subtropics. Acacia and Prosopis trees form N2-fixing nodules with a wide range of rhizobia, for example African acacias mainly with Sinorhizobium sp. and Mesorhizobium sp., and Australian acacias with Bradyrhizobium sp. Although dry and hot seasons restrict formation of N2-fixing nodules on Acacia and Prosopis spp., fully grown trees and their symbiotic partners are well adapted to survive in harsh growth conditions. This review on one hand deals with major constraints of arid and semiarid soils, i.e. drought, salinity and high soil temperature, which affect growth of trees and rhizobia, and on the other hand with adaptation mechanisms by which both organisms survive through unfavourable periods. In addition, defects in infection and nodulation processes due to various abiotic and biotic constraints are reviewed. This knowledge is important when Acacia and Prosopis seedlings are used for forestation of degraded areas in arid and semiarid tropics. PMID:15242281

  7. Robust markers reflecting phylogeny and taxonomy of rhizobia.

    Directory of Open Access Journals (Sweden)

    Yan Ming Zhang

    Full Text Available Genomic ANI (Average Nucleotide Identity has been found to be able to replace DNA-DNA hybridization in prokaryote taxonomy. The ANI of each of the core genes that has a phylogeny congruent with the reference species tree of rhizobia was compared to the genomic ANI. This allowed us to identify three housekeeping genes (SMc00019-truA-thrA whose ANI reflected the intraspecies and interspecies genomic ANI among rhizobial strains, revealing an ANI gap (≥2% between the inter- and intra-species comparisons. The intraspecies (96% and interspecies (94% ANI boundaries calculated from three genes (SMc00019-truA-thrA provided a criterion for bacterial species definition and confirmed 621/629 of known interspecies relationships within Bradyrhizobium, Mesorhizobium, Sinorhizobium and Rhizobium. Some widely studied strains should be renamed. The SMc00019-truA-thrA ANI also correlates well with the genomic ANI of strains in Agrobacterium, Methylobacterium, Ralstonia, Rhodopseudomonas, Cupriavidus and Burkholderia, suggesting their wide applicability in other bacteria.

  8. In Silico Identification for α-Amino-ε-Caprolactam Racemases by Using Information on the Structure and Function Relationship.

    Science.gov (United States)

    Payoungkiattikun, Wisarut; Okazaki, Seiji; Nakano, Shogo; Ina, Atsutoshi; H-Kittikun, Aran; Asano, Yasuhisa

    2015-07-01

    In silico identification for enzymes having desired functions is attractive because there is a possibility that numerous desirable enzymes have been deposited in databases. In this study, α-amino-ε-caprolactam (ACL) racemases were searched from the NCBI protein database. Four hundred thirteen fold-type I pyridoxal 5'-phosphate-dependent enzymes which are considered to contain sequences of ACL racemase were firstly obtained by submitting the sequence of ACL racemase from Achromobacter obae to the database. By identifying Lys241 as a key amino acid residue, 13 candidates for ACL racemase were selected. Then, putative ACL racemase genes were synthesized as codon-optimized sequences for expression in Escherichia coli. They were subcloned and expressed in E. coli BL21 and underwent His-tag purification. ACL and amino acid amide racemizing activities were detected among ten of the candidates. The locus tags Oant_4493, Smed_5339, and CSE45_2055 derived from Ochrobactrum anthropi ATCC49188, Sinorhizobium medicae WSM 419, and Citreicella sp. SE45, respectively, showed higher racemization activity against D- and L-ACLs rather than that of ACL racemase from A. obae. Our results demonstrate that the newly discovered ACL racemases were unique from ACL racemase from A. obae and might be useful for applications in dynamic kinetic resolution for D- or L-amino acid production. PMID:26206345

  9. Construction of the recombinant broad-host-range plasmids providing their bacterial hosts arsenic resistance and arsenite oxidation ability.

    Science.gov (United States)

    Drewniak, Lukasz; Ciezkowska, Martyna; Radlinska, Monika; Sklodowska, Aleksandra

    2015-02-20

    The plasmid pSinA of Sinorhizobium sp. M14 was used as a source of functional phenotypic modules, encoding proteins involved in arsenite oxidation and arsenic resistance, to obtain recombinant broad-host-range plasmids providing their bacterial hosts arsenic resistance and arsenite oxidative ability. An arsenite oxidation module was cloned into pBBR1MCS-2 vector yielding plasmid vector pAIO1, while an arsenic resistance module was cloned into pCM62 vector yielding plasmid pARS1. Both plasmid constructs were introduced (separately and together) into the cells of phylogenetically distant (representing Alpha-, Beta-, and Gammaproteobacteria) and physiologically diversified (unable to oxidize arsenite and susceptible/resistant to arsenite and arsenate) bacteria. Functional analysis of the modified strains showed that: (i) the plasmid pARS1 can be used for the construction of strains with an increased resistance to arsenite [up to 20mM of As(III), (ii) the presence of the plasmid pAIO1 in bacteria previously unable to oxidize As(III) to As(V), contributes to the acquisition of arsenite oxidation abilities by these cells, (iii) the highest arsenite utilization rate are observed in the culture of strains harbouring both the plasmids pAIO1 and pARS1, (iv) the strains harbouring the plasmid pAIO1 were able to grow on arsenic-contaminated mine waters (∼ 3.0 mg As L(-1)) without any supplementation. PMID:25617684

  10. Potential Emergence of Multi-quorum Sensing Inhibitor Resistant (MQSIR) Bacteria.

    Science.gov (United States)

    Koul, Shikha; Prakash, Jyotsana; Mishra, Anjali; Kalia, Vipin Chandra

    2016-03-01

    Expression of certain bacterial genes only at a high bacterial cell density is termed as quorum-sensing (QS). Here bacteria use signaling molecules to communicate among themselves. QS mediated genes are generally involved in the expression of phenotypes such as bioluminescence, biofilm formation, competence, nodulation, and virulence. QS systems (QSS) vary from a single in Vibrio spp. to multiple in Pseudomonas and Sinorhizobium species. The complexity of QSS is further enhanced by the multiplicity of signals: (1) peptides, (2) acyl-homoserine lactones, (3) diketopiperazines. To counteract this pathogenic behaviour, a wide range of bioactive molecules acting as QS inhibitors (QSIs) have been elucidated. Unlike antibiotics, QSIs don't kill bacteria and act at much lower concentration than those of antibiotics. Bacterial ability to evolve resistance against multiple drugs has cautioned researchers to develop QSIs which may not generate undue pressure on bacteria to develop resistance against them. In this paper, we have discussed the implications of the diversity and multiplicity of QSS, in acting as an arsenal to withstand attack from QSIs and may use these as reservoirs to develop multi-QSI resistance. PMID:26843692

  11. Recovery of symbiotic nitrogen fixing acacia rhizobia from Merzouga Desert sand dunes in South East Morocco - Identification of a probable new species of Ensifer adapted to stressed environments.

    Science.gov (United States)

    Sakrouhi, Ilham; Belfquih, Meryem; Sbabou, Laïla; Moulin, Patricia; Bena, Gilles; Filali-Maltouf, Abdelkarim; Le Quéré, Antoine

    2016-03-01

    Bacteria capable of nodulating Acacia tortilis and A. gummifera could be recovered from sand dunes collected in the Moroccan Merzouga desert. The trapping approach enabled the recovery of 17 desert rhizobia that all clustered within the Ensifer (Sinorhizobium) genus. Four isolates of the dominant genotype comprising 15 strains as well as 2 divergent strains were further characterized by MLSA. Phylogenetic analyzes indicated that the dominant genetic type was belonging to a new and yet undefined species within the Ensifer genus. Interestingly, housekeeping gene phylogenies showed that this possibly new species is also present in another desert but in India. Phylogenetic analyses of nifH and nodC sequences showed high sequence conservation among the Moroccan strains belonging to the dominant genotype but high divergence with sequences from Indian isolates suggesting acquisition of symbiotic genes through Horizontal Gene Transfer. These desert rhizobia were capable of growing in media containing high salt concentrations, under high pH and most of the strains showed growth at 45°C. Only recovered from desert type of Biome, yet, this new taxon appears particularly adapted to such harsh environment. PMID:26867773

  12. Changes in the population of seed bacteria of transgenerationally Cd-exposed Arabidopsis thaliana.

    Science.gov (United States)

    Truyens, S; Weyens, N; Cuypers, A; Vangronsveld, J

    2013-11-01

    Plant-associated bacteria can have beneficial effects on the growth and health of their host. Nevertheless, the role of endophytic bacteria present in seeds has not been investigated in depth. In this study, the cultivable endophytic population of seeds from Arabidopsis thaliana exposed to 2 μm cadmium for several generations (Cd seeds) was compared with a population isolated from seeds of plants that were never exposed to Cd (control seeds). We observed obvious differences between the two types of seed concerning genera present and phenotypic characteristics of the different isolates. Sinorhizobium sp. and Micrococcus sp. were only found in control seeds, while Pseudomonas sp., Bosea sp. and Paenibacillus sp. were only found in Cd seeds. Sphingomonas sp., Rhizobium sp., Acidovorax sp., Variovorax sp., Methylobacterium sp., Bacillus sp. and Staphylococcus sp. occurred in varying numbers in both types of seed. Metal tolerance and 1-aminocyclopropane-1-carboxylate deaminase activity were predominantly found in strains isolated from Cd seeds, while the production of siderophores, indole-3-acetic acid and organic acids was more prevalent in endophytes isolated from control seeds. These data support the hypothesis that certain endophytes are selected for transfer to the next generation and that their presence might be important for subsequent germination and early seedling development. PMID:23252960

  13. Endophytic bacteria from Piper tuberculatum Jacq.: isolation, molecular characterization, and in vitro screening for the control of Fusarium solani f. sp piperis, the causal agent of root rot disease in black pepper (Piper nigrum L.).

    Science.gov (United States)

    Nascimento, S B; Lima, A M; Borges, B N; de Souza, C R B

    2015-01-01

    Endophytic bacteria have been found to colonize internal tissues in many different plants, where they can have several beneficial effects, including defense against pathogens. In this study, we aimed to identify endophytic bacteria associated with roots of the tropical piperaceae Piper tuberculatum, which is known for its resistance to infection by Fusarium solani f. sp piperis, the causal agent of black pepper (Piper nigrum) root rot disease in the Amazon region. Based on 16S rRNA gene sequence analysis, we isolated endophytes belonging to 13 genera: Bacillus, Paenibacillus, Pseudomonas, Enterobacter, Rhizobium, Sinorhizobium, Agrobacterium, Ralstonia, Serratia, Cupriavidus, Mitsuaria, Pantoea, and Staphylococcus. The results showed that 56.52% of isolates were associated with the phylum Proteobacteria, which comprised α, β, and γ classes. Other bacteria were related to the phylum Firmicutes, including Bacillus, which was the most abundant genus among all isolates. Antagonistic assays revealed that Pt12 and Pt13 isolates, identified as Pseudomonas putida and Pseudomonas sp, respectively, were able to inhibit F. solani f. sp piperis growth in vitro. We describe, for the first time, the molecular identification of 23 endophytic bacteria from P. tuberculatum, among which two Pseudomonas species have the potential to control the pathogen responsible for root rot disease in black pepper in the Amazon region. PMID:26214435

  14. AcEST: DK952990 [AcEST

    Lifescience Database Archive (English)

    Full Text Available AVRGAGYELR 148 >sp|Q9X5X3|ATCU_SINMW Copper-transporting P-type ATPase OS=Sinorhizobium medicae (stra..... 35 0.29 sp|A2VDJ0|T131L_HUMAN Transmembrane protein 131-like OS=Homo sap... 31 5.5 sp|Q4X0S7|DPH1_ASPFU D...t: 134 SALAAAVKGAGYGIR 148 >sp|A2VDJ0|T131L_HUMAN Transmembrane protein 131-like OS=Homo sapiens GN=KIAA0922...|A6X3Z4|A6X3Z4_OCHA4 Heavy metal translocating P-type ATPase O... 36 1.5 tr|A0AJV7|A0AJV7_LISW6 Complete genome OS=Listeria...: Swiss-Prot sp_hit_id P58342 Definition sp|P58342|ATCU2_RHIME Copper-transporting ATPase 2 OS=Rhizobium mel

  15. [Analysis of Symbiotic Genes of Leguminous Plants Nodule Bacteria Grown in the Southern Urals].

    Science.gov (United States)

    Baymiev, An Kh; Ivanova, E S; Gumenko, R S; Chubukova, O V; Baymiev, Al Kh

    2015-12-01

    Bacterial strains isolated from the nodules, tissues, and root surface of wild legumes growing in the Southern Urals related to the tribes Galegeae, Hedysareae, Genisteae, Trifolieae, and Loteae were examined for the presence in their genomes of symbiotic (sym) genes. It was found that the sym-genes are present in microorganisms isolated only from the nodules of the analyzed plants (sym+ -strains). Phylogenetic analysis of sym+ -strains on the basis of a comparative analysis of 16S rRNA gene sequences showed that sym+ -strains belong to five families of nodule bacteria: Mesorhizobium, Bradyrhizobium, Sinorhizobium, Rhizobium, and Phyllobacterium. A study the phylogeny of the sym-genes showed that the nodule bacteria of leguminous plants of the Southern Urals at the genus level are mainly characterized by a parallel evolution of symbiotic genes and the 16S rRNA gene. Thus, cases of horizontal transfer of sym genes, which sometimes leads to the formation of certain types of atypical rhizobial strains ofleguminous plants, are detected in nodule bacteria populations. PMID:27055295

  16. Concurrent synthesis and release of nod-gene-inducing flavonoids from alfalfa roots

    International Nuclear Information System (INIS)

    Flavonoid signals from alfalfa (Medicago sativa L.) induce transcription of nodulation (nod) genes in Rhizobium meliloti. Alfalfa roots release three major nod-gene inducers: 4',7-dihydroxyflavanone, 4',7-dihydroxyflavone, and 4,4'-dihydroxy-2'-methoxychalcone. The objective of the present study was to define temporal relationships between synthesis and exudation for those flavonoids. Requirements for concurrent flavonoid biosynthesis were assessed by treating roots of intact alfalfa seedlings with [U-14C]-L-phenylalanine in the presence or absence of the phenylalanine ammonia-lyase inhibitor L-2-aminoxy-3-phenylpropionic acid (AOPP). In the absence of AOPP, each of the three flavonoids in exudates contained 14C. In the presence of AOPP, 14C labeling and release of all the exuded nod-gene inducers were reduced significantly. AOPP inhibited labeling and release of the strongest nod-gene inducer, methoxychalcone, by more than 90%. The release process responsible for exudation of nod-gene inducers appears to be specific rather than a general phenomenon such as a sloughing off of cells during root growth

  17. Radioactive isotope uptake in a grass-legume association

    International Nuclear Information System (INIS)

    The radioactive uptake of Medicago sativa and Rye grass in a pasture exposed to the fallout from the Chernobyl reactor accident, was determined in four consecutive harvests covering a period of one year after the accident. In plants of Medicago sativa, inoculated with an effective Rhizobia meliloti strain isolated from Greek soils, a high degree of biological nitrogen fixation was observed at all harvests using N-15 techniques. At the second and third harvests, the percentage nitrogen derived from fixation (%NdfF), the percentage nitrogen derived from soil (%NdfS), as well as the radioactive uptake from the soil remained stable. At the fourth harvest, however, the %NdfF decreased while the %NdfS and the radioactive uptake from soil significantly increased. At the first harvest the radioactivity in both plants, caused mainly by direct fallout contamination, was considerably higher than that observed at the later harvests. Medicago sativa contained significantly less radioactivity than the grass at all harvests, although both plants were grown under the same environmental conditions. Even at the fourth harvest, almost one year after the initial contamination, the radioactivity of grass remained at high levels (20 Bq g-1 of protein) while in Medicago sativa it assumed considerably lower values (3.6 Bq g-1 of protein). A possible involvement of biological nitrogen fixation in the reduction of radioactive uptake is discussed. Finally, certain practical conclusions are drawn with respect to a safer management of pastures exposed to radioactivity. (author)

  18. Cell surface properties of rhizobial isolated from soils contaminated with hydrocarbons: hydrophobicity and adhesion to sandy soil

    Energy Technology Data Exchange (ETDEWEB)

    Mehmannavaz, R. [INRS-Institut Armand-Frappier, Centre de microbiologie et biotechnologie, Pointe-Claire, Quebec (Canada); McGill Univ., Ste-Anne-de-Bellevue, Quebec (Canada); Prasher, S.O. [McGill Univ., Ste-Anne-de-Bellevue, Quebec (Canada); Ahmad, D. [INRS-Institut Armand-Frappier, Centre de microbiologie et biotechnologie, Pointe-Claire, Quebec (Canada)

    2001-02-01

    Ten strains of Rhizobium meliloti and two non-rhizobial strains, Escherichia coli JM105 and Comomonas testosteroni B-356, were studied for their behaviour in soil and water matrices by determining their hydrophobicity, as measured by bacterial adherence to n-octane, and adhesion, as measured by their retention on sandy soil particles. The hydrophobicity values for the rhizobial strains were similar to that for E. coli (around 15%), whereas C. testosteroni, which belongs to the Pseudomonads group, showed a significantly higher level (33%). Both non-rhizobial strains, however, showed higher levels of adhesion, (85% and 78%, respectively) than did the rhizobial strains ({approx}55%). The cell surface properties of the rhizobial strains were influenced by the composition of the growth media used, being significantly higher with nutrient-rich media. The nature or level of contaminants in the soil from which these strains were originally isolated did not, however, influence these properties. These characteristics are important in determining the fate of bacteria in the unsaturated subsurface soil environment because of their influence on the vertical transport, distribution and survival. Information about these characteristics will be particularly useful in choosing stains for agricultural applications (e.g., as biofertilizers or biocontrol agents) or in situ soil environment operations (e.g., bioaugmentation for bioremediation of pollutants). (Author)

  19. Sequence and structural organization of a nif A-like gene and part of a nifB-like gene of Herbaspirillum seropedicae strain Z78.

    Science.gov (United States)

    Souza, E M; Funayama, S; Rigo, L U; Yates, M G; Pedrosa, F O

    1991-07-01

    The deduced amino acid sequence derived from the sequence of a fragment of DNA from the free-living diazotroph Herbaspirillum seropedicae was aligned to the homologous protein sequences encoded by the nifA genes from Azorhizobium caulinodans, Rhizobium leguminosarum, Rhizobium meliloti and Klebsiella pneumoniae. High similarity was found in the central domain and in the C-terminal region. The H. seropedicae putative NifA sequence was also found to contain an interdomain linker similar to that conserved among rhizobial NifA proteins, but not K. pneumoniae or Azotobacter vinelandii. Analysis of the regulatory sequences found 5' from nifA indicated that the expression of this gene in H. seropedicae is likely to be controlled by NifA, NtrC and RpoN, as judged by the presence of specific NifA- and NtrC-binding sites and characteristic -24/-12 promoters. Possible additional regulatory features included an 'anaerobox' and a site for integration host factor. The N-terminus of another open reading frame was found 3' from nifA and tentatively identified as nifB by amino acid sequence comparison. The putative nifB promoter sequence suggests that expression of H. seropedicae nifB may be activated by NifA and dependent on RpoN. PMID:1840608

  20. Nucleotide sequence of the fixABC region of Azorhizobium caulinodans ORS571: similarity of the fixB product with eukaryotic flavoproteins, characterization of fixX, and identification of nifW.

    Science.gov (United States)

    Arigoni, F; Kaminski, P A; Hennecke, H; Elmerich, C

    1991-03-01

    The nucleotide sequence of a 4.1 kb DNA fragment containing the fixABC region of Azorhizobium caulinodans was established. The three gene products were very similar to the corresponding polypeptides of Rhizobium meliloti. The C-terminal domains of both fixB products displayed a high degree of similarity with the alpha-subunits of rat and human electron transfer flavoproteins, suggesting a role for the FixB protein in a redox reaction. Two open reading frames (ORF) were found downstream of fixC. The first ORF was identified as fixX on the basis of sequence homology with fixX from several Rhizobium and Bradyrhizobium strains. The second ORF potentially encoded a 69 amino acid product and was found to be homologous to a DNA region in the Rhodobacter capsulatus nif cluster I. Insertion mutagenesis of the A. caulinodans fixX gene conferred a Nif- phenotype to bacteria growth in the free-living state and a Fix- phenotype in symbiotic association with the host plant Sesbania rostrata. A crude extract from the fixX mutant had no nitrogenase activity. Furthermore, data presented in this paper also indicate that the previously identified nifO gene located upstream of fixA was probably a homologue of the nifW gene of Klebsiella pneumoniae and Azotobacter vinelandii. PMID:1850088

  1. Development of an inhibitive enzyme assay for copper.

    Science.gov (United States)

    Shukor, M Y; Bakar, N A; Othman, A R; Yunus, I; Shamaan, N A; Syed, M A

    2009-01-01

    In this work the development of an inhibitive assay for copper using the molybdenum-reducing enzyme assay is presented. The enzyme is assayed using 12-molybdophosphoric acid at pH 5.0 as an electron acceptor substrate and NADH as the electron donor substrate. The enzyme converts the yellowish solution into a deep blue solution. The assay is based on the ability of copper to inhibit the molybdenum-reducing enzyme from the molybdate-reducing Serratia sp. Strain DRY5. Other heavy metals tested did not inhibit the enzyme at 10 mg l(-1). The best model with high regression coefficient to measure copper inhibition is one-phase binding. The calculated IC50 (concentration causing 50% inhibition) is 0.099 mg l(-1) and the regression coefficient is 0.98. The comparative LC50, EC50 and IC50 data for copper in different toxicity tests show that the IC50 value for copper in this study is lower than those for immobilized urease, bromelain, Rainbow trout, R. meliloti, Baker's Yeast dehydrogenase activity Spirillum volutans, P. fluorescens, Aeromonas hydrophilia and synthetic activated sludge assays. However the IC50 value is higher than those for Ulva pertusa and papain assays, but within the reported range for Daphnia magna and Microtox assays. PMID:20112861

  2. The center for plant and microbial complex carbohydrates at the University of Georgia Complex Carbohydrate Research Center

    Energy Technology Data Exchange (ETDEWEB)

    Albersheim, P.; Darvill, A.

    1991-08-01

    Research from the Complex Carbohydrates Research Center at the University of Georgia is presented. Topics include: Structural determination of soybean isoflavones which specifically induce Bradyrhizobium japonicum nodD1 but not the nodYABCSUIJ operon; structural analysis of the lipopolysaccharides (LPSs) from symbiotic mutants of Bradyrhizobium japonicum; structural characterization of lipooligosaccharides from Bradyrhizobium japonicum that are required for the specific nodulation of soybean; structural characterization of the LPSs from R. Leguminosarum biovar phaseoli, the symbiont of bean; characterization of bacteroid-specific LPS epitopes in R. leguminosarum biovar viciae; analysis of the surface polysaccharides of Rhizobium meliloti mutants whose lipopolysaccharides and extracellular polysaccharides can have the same function in symbiosis; characterization of a polysaccharide produced by certain Bradyrhizobium japonicum strains within soybean nodules; structural analysis of a streptococcal adhesin polysaccharide receptor; conformational studies of xyloglucan, the role of the fucosylated side chain in surface-specific cellulose-xyloglucan interactions; the structure of an acylated glucosamine oligosaccharide signal molecule (nod factor) involved in the symbiosis of Rhizobium leguminosarum biovar viciae with its host Vicia sativa; investigating membrane responses induced by oligogalacturonides in cultured cells; the polygalacturonase inhibitor protein; characterization of the self-incompatability glycoproteins from Petunia hybrida; investigation of the cell wall polysaccharide structures of Arabidopsis thaliana; and the glucan inhibition of virus infection of tabacco.

  3. The center for plant and microbial complex carbohydrates at the University of Georgia Complex Carbohydrate Research Center. Annual report, September 15, 1990--December 31, 1991

    Energy Technology Data Exchange (ETDEWEB)

    Albersheim, P.; Darvill, A.

    1991-08-01

    Research from the Complex Carbohydrates Research Center at the University of Georgia is presented. Topics include: Structural determination of soybean isoflavones which specifically induce Bradyrhizobium japonicum nodD1 but not the nodYABCSUIJ operon; structural analysis of the lipopolysaccharides (LPSs) from symbiotic mutants of Bradyrhizobium japonicum; structural characterization of lipooligosaccharides from Bradyrhizobium japonicum that are required for the specific nodulation of soybean; structural characterization of the LPSs from R. Leguminosarum biovar phaseoli, the symbiont of bean; characterization of bacteroid-specific LPS epitopes in R. leguminosarum biovar viciae; analysis of the surface polysaccharides of Rhizobium meliloti mutants whose lipopolysaccharides and extracellular polysaccharides can have the same function in symbiosis; characterization of a polysaccharide produced by certain Bradyrhizobium japonicum strains within soybean nodules; structural analysis of a streptococcal adhesin polysaccharide receptor; conformational studies of xyloglucan, the role of the fucosylated side chain in surface-specific cellulose-xyloglucan interactions; the structure of an acylated glucosamine oligosaccharide signal molecule (nod factor) involved in the symbiosis of Rhizobium leguminosarum biovar viciae with its host Vicia sativa; investigating membrane responses induced by oligogalacturonides in cultured cells; the polygalacturonase inhibitor protein; characterization of the self-incompatability glycoproteins from Petunia hybrida; investigation of the cell wall polysaccharide structures of Arabidopsis thaliana; and the glucan inhibition of virus infection of tabacco.

  4. A multiple path photonic lab on a chip for parallel protein concentration measurements.

    Science.gov (United States)

    Rodríguez-Ruiz, Isaac; Conejero-Muriel, Mayte; Ackermann, Tobias N; Gavira, José A; Llobera, Andreu

    2015-02-21

    We propose a PDMS-based photonic system for the accurate measurement of protein concentration with minute amounts of the sample. As opposed to the state of the art approach, in the multiple path photonic lab on a chip (MPHIL), analyte concentration or molar absorptivity is obtained with a single injection step, by performing simultaneous parallel optical measurements varying the optical path length. Also, as opposed to the standard calibration protocol, the MPHIL approach does not require a series of measurements at different concentrations. MPHIL has three main advantages: firstly the possibility of dynamically selecting the path length, always working in the absorbance vs. concentration linear range for each target analyte. Secondly, a dramatic reduction of the total volume of the sample required to obtain statistically reliable results. Thirdly, since only one injection is required, the measurement time is minimized, reducing both contamination and signal drifts. These characteristics are clearly advantageous when compared to commercial micro-spectrophotometers. The MPHIL concept was validated by testing three commercial proteins, lysozyme (HEWL), glucose isomerase (d-xylose-ketol-isomerase, GI) and Aspergillus sp. lipase L (BLL), as well as two proteins expressed and purified for this study, B. cereus formamidase (FASE) and dihydropyrimidinase from S. meliloti CECT41 (DHP). The use of MPHIL is also proposed for any spectrophotometric measurement in the UV-VIS range, as well as for its integration as a concentration measurement platform in more advanced photonic lab on a chip systems. PMID:25537135

  5. Diversity of root nodule bacteria from leguminous crops

    Directory of Open Access Journals (Sweden)

    Agrawal Pooja

    2016-01-01

    Full Text Available In the present study, a total of 353 nodule-associated bacteria were isolated from 220 legume plant samples belonging to Cicer arietinum (85, Glycine max (74, Vigna radiata (21 and Cajanus cajan (40. A total of 224 bacteria were identified as fast-growing Rhizobium spp. on the basis of differential staining (Gram staining and carbol fuchsin staining and biochemical tests. All the isolates were tested for indole acetic acid production (IAA, phosphate solubilization and siderophore production on plate assay. To examine the effect of volatile organic metabolites (VOM and water soluble soil components (WSSC on nodule bacteria, culture conditions were optimized by observing the effects of various parameters such as pH, salt content and temperatures on the growth of bacteria. Selected rhizobia were subjected to random amplified polymorphic DNA (RAPD and amplified ribosomal DNA restriction analysis (ARDRA analysis to identify their species. On the basis of RAPD and ARDRA, 10 isolates were identified as Rhizobium meliloti. In this study, Rhizobium GO4, G16, G20, G77, S43, S81, M07, M37, A15 and A55 were observed as the best candidates among the tested bacteria and can be further used as potent bioinoculants.

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

    Science.gov (United States)

    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

  7. Phylogenetic Diversity of Ammopiptanthus Rhizobia and Distribution of Rhizobia Associated with Ammopiptanthus mongolicus in Diverse Regions of Northwest China.

    Science.gov (United States)

    Zhao, Liang; Wang, Xinye; Huo, Haibo; Yuan, Guiji; Sun, Yali; Zhang, Dehui; Cao, Ying; Xu, Lin; Wei, Gehong

    2016-07-01

    Aiming to investigate the diversity and distribution of rhizobia associated with Ammopiptanthus, an endangered evergreen legume widely distributed in deserts, we characterized a total of 219 nodule isolates from nine sampling sites in Northwest China with different soil characteristics based upon restriction fragment length polymorphism (RFLP) analysis of 16S ribosomal RNA (rRNA) and symbiotic genes (nodC and nifH). Ten isolates representing different 16S rRNA-RFLP types were selected for further sequence analyses of 16S rRNA and four housekeeping genes. As results, nine genospecies belonging to the genera Ensifer, Neorhizobium, Agrobacterium, Pararhizobium, and Rhizobium could be defined among the isolates. The nodC and nifH phylogenies of 14 isolates representing different symbiotic-RFLP types revealed five lineages linked to Ensifer fredii, Ensifer meliloti, Rhizobium leguminosarum, Mesorhizobium amorphae, and Rhizobium gallicum, which demonstrated the various origins and lateral transfers of symbiotic genes between different genera and species. The rhizobial diversities of Ammopiptanthus mongolicus varied among regions, and the community compositions of rhizobia associated with A. mongolicus were significantly different in wild and cultured fields. Constrained correspondence analysis showed that the distribution of A. mongolicus rhizobia could be explained by available potassium content and that the assembly of symbiotic types was mainly affected by available phosphorus content and carbon-nitrogen ratio. PMID:27079453

  8. Sensitivity of some nitrogen fixers and the target pest Fusarium oxysporum to fungicide thiram.

    Science.gov (United States)

    Osman, Awad G; Sherif, Ashraf M; Elhussein, Adil A; Mohamed, Afrah T

    2012-03-01

    This study was carried out to investigate the toxic effects of the fungicide thiram (TMTD) against five nitrogen fixers and the thiram target pest Fusarium oxysporum under laboratory conditions. Nitrogen fixing bacteria Falvobacterium showed the highest values of LD(50) and proved to be the most resistant to the fungicide followed by Fusarium oxysporum, while Pseudomonas aurentiaca was the most affected microorganism. LD(50) values for these microorganisms were in 2-5 orders of magnitude lower in comparison with LD(50) value for Fusarium oxysporum. Thiram was most toxic to Pseudomonas aurentiaca followed by Azospirillum. The lowest toxicity index was recorded for Fusarium oxysporum and Flavobacterium. The slope of the curve for Azomonas, Fusarium oxysporum and Flavobacterium is more steep than that of the other curves, suggesting that even a slight increase of the dose of the fungicide can cause a very strong negative effect. Thiram was more selective to Pseudomonas aurentiaca followed by Azospirillum, Rhizobium meliloti and Azomonas. The lowest selectivity index of the fungicide was recorded for Falvobacterium followed by Fusarium oxysporum. The highest safety coefficient of the fungicide was assigned for Flavobacterium, while Pseudomonas aurentiaca showed the lowest value. PMID:22783146

  9. EFFECTS OF INORGANIC FERTILIZERS AND RHIZOBIAL INOCULATION ON GROWTH, NODULATION AND TANNIN CONTENT OF ACACIELLA ANGUSTISSIMA (MILL. BRITTON & ROSE EFECTO DE LOS FERTILIZANTES INORGÁNICOS Y LA INOCULACIÓN RIZOBIAL SOBRE CRECIMIENTO, NODULACIÓN Y CONTENIDO DE TANINOS EN ACACIELLA ANGUSTISSIMA (MILL. BRITTON & ROSE

    Directory of Open Access Journals (Sweden)

    Víctor M Ruiz-Valdiviezo

    2009-01-01

    Full Text Available The effects of different inorganic fertilizers and rhizobial inoculation on shoot height, total shoot and root dry weight, nodule number, total shoot nitrogen, nitrogenase activity and tannic acid content of Acaciella angustissima (Mill. Britton & Rose were investigated in the laboratory. Seedlings were grown in a climate chamber in glass tubes containing sterilized mixture of vermiculite and peat moss, and treated with combinations of nitrogen (N at 45 mg plant¹, phosphorus (P at 30 mg plant¹, potassium (K at 20 mg plant¹ and inoculated with the bacterium Sinorhizobium mexicanum. The combined applications of N, P or K to uninoculated plants increased shoot height and dry weight as compared to the unamended plantlets. The tannin content in uninoculated plants was highest when amended with P+K. Treatment had a significant effect on plant growth, nodulation and tannin content varied. The plants treated with P + K + S. mexicanum had significantly longer shoot height, total shoot and root dry weight, nodule number, total shoot nitrogen, nitrogenase activity and tannic acid content in comparison with unamended plants. It was found that N reduced number of nodules, tannin content and nitrogenase activity of A. angustisisma. As such, farmers should refrain from applying N fertilizer, but could apply P and K to maximize tannin production in A. angustissima.Se investigaron en el laboratorio los efectos de diferentes fertilizantes inorgánicos y la inoculación rizobial sobre la altura de planta, peso seco total de planta, peso seco de raíz, el número de nodulos, el nitrógeno total de la planta, la actividad de la nitrogenasa y el contenido de ácido tánico de Acaciella angustissima (Mili. Britton & Rose. Las plántulas fueron crecidas en una cámara climática en tubos de vidrio conteniendo una mezcla de vermiculita y turba, y tratadas con las combinaciones de nitrógeno (N en 45 mg planta"¹, fósforo (P en 30 mg planta"¹, potasio (K en 20 mg

  10. Caracterização de rizóbios isolados de Jacatupé cultivado em solo salino no Estado de Pernanbuco, Brasil Characterization of isolated rhizobia from Pachyrhyzus erosus L. cultivated in saline soil of the State of Pernambuco, Brazil

    Directory of Open Access Journals (Sweden)

    Ana Dolores Santiago de Freitas

    2007-01-01

    Full Text Available Pesquisas sobre a biodiversidade microbiológica de solos salinos envolvem a busca por genótipos tolerantes a esse tipo de estresse ambiental. Dados genotípicos correlacionados às características morfológicas, fisiológicas e bioquímicas de bactérias fornecem informações importantes para sua identificação e agrupamento. Este trabalho objetivou caracterizar rizóbios provenientes de solos salinos, do Agreste e Sertão de Pernambuco, utilizando jacatupé (Pachyrhizus erosus L. Urban como planta-isca. Os testes foram efetuados em meio YMA e as características culturais observadas em 24 isolados foram as seguintes: mudança de pH, tempo de crescimento, transparência, forma, borda, produção de exopolissacarídeo das colônias e resistência à salinidade. Os testes moleculares utilizando análise por PCR (reação em cadeia da polimerase por meio de seqüências repetitivas de DNA amplificadas com o primer BOX envolveram 13 isolados. Os resultados revelaram alta diversidade fenotípica e genotípica entre os isolados nativos. As características culturais e genéticas desses isolados foram comparados com 19 estirpes de referência. Os isolados NFB746 e NFB747 tiveram alta semelhança entre si e também com as estirpes Rhizobium sp. NGR234 (BR2406 e Mesorhizobium ciceri USDA3383 (BR521. O isolado NFB742, possivelmente, era da mesma espécie de M. ciceri (BR521. Com relação ao isolado NFB741, a semelhança com as bactérias Rhizobium tropici IIA CFN299T (BR10016 e Sinorhizobium terangue USDA4894 (BR527 foi de 87%. Os demais isolados, praticamente, formaram grupos independentes quando comparados com as estirpes de referência. Os resultados foram de grande relevância para diagnosticar novas espécies de rizóbios nativos altamente tolerantes a estresses ambientais.Investigation on microbiological biodiversity in the saline soils involves searching for tolerant genotypes to this type of emvironmental stress. Genotypic data associated to

  11. Effect of the cathode potential and sulfate ions on nitrate reduction in a microbial electrochemical denitrification system.

    Science.gov (United States)

    Nguyen, Van Khanh; Park, Younghyun; Yang, Heechun; Yu, Jaecheul; Lee, Taeho

    2016-06-01

    Recently, bioelectrochemical systems have been demonstrated as advantageous for denitrification. Here, we investigated the nitrate reduction rate and bacterial community on cathodes at different cathode potentials [-300, -500, -700, and -900 mV vs. standard hydrogen electrode (SHE)] in a two-chamber microbial electrochemical denitrification system and effects of sulfate, a common nitrate co-contaminant, on denitrification efficiency. The results indicated that the highest nitrate reduction rates (3.5 mg L(-1) days(-1)) were obtained at a cathode potential of -700 mV, regardless of sulfate presence, while a lower rate was observed at a more negative cathode potential (-900 mV). Notably, although sulfate ions generally inhibited nitrate reduction, this effect was absent at a cathode potential of -700 mV. Polymerase chain reaction-denaturing gradient gel electrophoresis revealed that bacterial communities on the graphite-felt cathode were significantly affected by the cathode potential change and sulfate presence. Shinella-like and Alicycliphilus-like bacterial species were exclusively observed on cathodes in reactors without sulfate. Ochrobactrum-like and Sinorhizobium-like bacterial species, which persisted at different cathode potentials irrespective of sulfate presence, were shown to contribute to bioelectrochemical denitrification. This study suggested that a cathode potential of around -700 mV versus SHE would ensure optimal nitrate reduction rate and counteract inhibitory effects of sulfate. Additionally, sulfate presence considerably affects denitrification efficiency and microbial community of microbial electrochemical denitrification systems. PMID:27021845

  12. Effect of plant growth promoting rhizobia on seed germination and seedling traits in Acacia senegal

    Directory of Open Access Journals (Sweden)

    S.K. Singh

    2011-11-01

    Full Text Available Among arid zone tree species, Acacia senegal and Prosopis cineraria are the most important dryland resources of Western Rajasthan desert ecosystem. Due to ecological, biological and molecular similarities, they are often studied together. The climatic conditions in this region restrict the build-up of soil organic matter and soils are generally deficient in nitrogen. Studies were carried out to isolate and molecularly characterize the diverse group of plant growth promoting rhizobacteria from root nodules of native A. senegal and P. cineraria and their effect on seed germination and seedling traits in two genotypes of A. senegal. The direct sequencing of 16S rDNA region resulted in molecular identification of plant growth promoting rhizobacteria as Bacillus licheniformis, Sinorhizobium saheli isolated from root nodules of A. senegal and S. kostiense and S. saheli isolated from root nodules of P. cineraria. The partial sequences of 16S rDNA were assigned Gen accession numbers HQ738496, HQ738499, HQ738506 and HQ738508. Scarification treatment with sulphuric acid (98% for 15 minutes was able to break the exogenous seed dormancy and enhanced germination percentage in control treatment to 90% and 92.5% in A. senegal in genotypes CAZRI 113AS and CAZRI 35AS, respectively. The treatments with Bacillus licheniformis or S. kostiense, either inoculated individually or as coinoculants, had positive effect on phenotypic traits of germination. Two A. senegal genotypes exhibited significant differences with regard to all the phenotypic traits. On the other hand, treatments with S. saheli isolated from either A. senegal or P. cineraria had negative effects on germination and related phenotypic traits. Values of the coeffivient of determination (R2 over 80% for root length versus shoot length, root/shoot ratio and seedling weight respectively validate that the observed attributes are inter-dependable and linear progression trend can be predicted.

  13. CARACTERISATION PRELIMINAIRE DES RHIZOBIA ISOLEES A PARTIR DES NODOSITES DE CICER ARIETINUM L. CULTIVE DANS LE NORD-EST ALGERIEN

    Directory of Open Access Journals (Sweden)

    D. CHEKIREB

    2011-10-01

    Full Text Available Dans cette étude nous nous sommes intéressés au rhizobia nodulant Cicer arietinum L. (FLIP 90-13 cultivé dans la wilaya de Guelma (Algérie. Des quarante cinq isolats obtenus à partir de nodosités effectives de Cicer arietinum L, neuf ont nodulé leur plante hôte et deux de ces souches ont nodulé Medicago sp. Les dendrogrammes obtenus après analyse numérique des résultats des tests API 20NE et API 50CH montrent une diversité de ces rhizobia et permet d’apparenter la souche CAO08 au genre Sinorhizobium. D’autres caractères biochimiques comme la production d’acide ou d’alkali et la production du 3-céto-lactose ainsi que la résistance au stress salin, aux antibiotiques et à la variation de la température ont été testés. Les résultats obtenus indiquent que la quasi-totalité des souches acidifie le milieu YEMA en présence de BTB et qu’aucune d’entre elles ne produit le 3-céto-lactose. Toutes les souches testées peuvent croitre en présence de 2% de NaCl et sont capables de pousser à une température de 42°C. D’autre part, ces souches montrent une résistance à des concentrations de kanamycine (100µg/ml et de pénicilline G (60µg/ml.

  14. Cloning and Sequencing of the DNA Fragment Related to Salt Tolerance of Halomonas sp.C6%盐单胞菌C6与耐盐有关DNA片段的克隆和序列分析

    Institute of Scientific and Technical Information of China (English)

    王海洪; 樊振川; 曾静; 杨苏声

    1999-01-01

    提取盐单胞菌(Halomonas)C6的总DNA,用Sau3AⅠ部分酶切,回收15~30 kb的DNA片段,以pLAFR3为载体在大肠杆菌(E.coli)中构建了该菌的基因文库.以C6的基因文库为供体,以费氏中华根瘤菌(Sinorhizobium fredii)盐敏感菌株RC3-3r为受体,在辅助质粒pRK2013的协助下进行三亲本杂交,在选择培养基上筛选到接合子RWH15和RWH17.质粒检测表明,这两个接合子分别含有重组质粒pWH15和pWH17.通过三亲本杂交和功能互补的方法,对质粒pWH15进行两次亚克隆,最终得到3.2 kb的DNA片段.经检测,该片段能使RC3-3r恢复耐盐性.通过DNA测序及开放阅读框架(ORFs)分析,发现该片段上有4个开放阅读框架,其功能有待于进一步研究.

  15. A Study on Co-Metabolic Biodegradation of Phenol and TCE by Mixed Culture PCL%高效降解菌剂PCL对苯酚及TCE的共代谢降解性能研究

    Institute of Scientific and Technical Information of China (English)

    张施阳

    2016-01-01

    从长期受氯代烃和酚类污染的土壤中驯化筛选得到能以苯酚为共代谢基质降解TCE的混合菌群PCL,其主要由博代氏杆菌(Bordetella sp.)和中华根瘤菌(Sinorhizobium sp.)组成.采用摇瓶振荡培养方法,研究了不同环境条件对混合菌群PCL共代谢苯酚和TCE效能的影响.结果表明,在30℃、pH 7.5条件下,200 mg/L苯酚能被PCL在4d内代谢完全,并且50 mg/L TCE在8d内的降解率能达到85.6%,以8mmol/L H2O2作为氧源,能使TCE降解率提高到91.18%.混合菌群PCL对苯酚和TCE的降解动力学可用Haldane方程来描述,利用非线性拟合求得各自对应的动力学参数k、km、ki分别为0.749/d、46.67 mg/L、386.16 mg/L和0.1332/d、31.15mg/L、0.044 5 mg/L,且拟合效果很好.

  16. Ensifer glycinis sp. nov., a rhizobial species associated with species of the genus Glycine.

    Science.gov (United States)

    Yan, Hui; Yan, Jun; Sui, Xin Hua; Wang, En Tao; Chen, Wen Xin; Zhang, Xiao Xia; Chen, Wen Feng

    2016-09-01

    Rhizobial strains from root nodules of Astragalus mongholicus and soybean (Glycine max) were characterized phylogenetically as members of the genus Ensifer (formerly named Sinorhizobium), based on 16S rRNA gene sequence comparisons. Results based upon concatenated sequence analysis of three housekeeping genes (recA, atpD and glnII, ≤ 93.8 % similarities to known species) and average nucleotide identity (ANI) values of whole genome sequence comparisons (ranging from 89.6 % to 83.4 % to Ensifer fredii and Ensifer saheli, respectively) indicated the distinct positions of these novel strains within the genus Ensifer. Phylogeny of symbiotic genes (nodC and nifH) of three novel strains clustered them with rhizobial species Ensifer fredii and Ensifer sojae, both isolated from nodules of Glycine max. Cross-nodulation tests showed that the representative strain CCBAU 23380T could form root nodules with nitrogen fixation capability on Glycine soja, Albizia julibrissin, Vigna unguiculata and Cajanus cajan, but failed to nodulate Astragalus mongholicus, its original host legume. Strain CCBAU 23380T formed inefficient nodules on G. max, and it did not contain 18 : 0, 18 : 1ω7c 11-methyl or summed feature 1 fatty acids, which differed from other related strains. Failure to utilize malonic acid as a carbon source distinguished strain CCBAU 23380T from the type strains of related species. The genome size of CCBAU 23380T was 6.0 Mbp, comprising 5624 predicted genes with DNA G+C content of 62.4 mol%. Based on the results above, a novel species, Ensifer glycinis sp. nov., is proposed, with CCBAU 23380T (=LMG 29231T =HAMBI 3645T) as the type strain. PMID:27125987

  17. Distribution of hydrogen-metabolizing bacteria in alfalfa field soil

    International Nuclear Information System (INIS)

    H2 evolved by alfalfa root nodules during the process of N2 fixation may be an important factor influencing the distribution of soil bacteria. To test this hypothesis under field conditions, over 700 bacterial isolates were obtained from fallow soil or from the 3-mm layer of soil surrounding alfalfa (Medicago sativa L.) root nodules, alfalfa roots, or bindweed (Convolvulus arvensis L.) roots. Bacteria were isolated under either aerobic or microaerophilic conditions and were tested for their capacity to metabolize H2. Isolates showing net H2 uptake and 3H2 incorporation activity under laboratory conditions were assigned a Hup+ phenotype, whereas organisms with significant H2 output capacity were designated as a Hout+ phenotype. Under aerobic isolation conditions two Hup+ isolates were obtained, whereas under microaerophilic conditions five Hup+ and two Hout+ isolates were found. The nine isolates differed on the basis of 24 standard bacteriological characteristics or fatty acid composition. Five of the nine organisms were isolated from soil around root nodules, whereas the other four were found distributed among the other three soil environments. On the basis of the microaerophilic isolations, 4.8% of the total procaryotic isolates from soil around root nodules were capable of oxidizing H2, and 1.2% could produce H2. Two of the Hup+ isolates were identified as Rhizobium meliloti by root nodulation tests, but the fact that none of the isolates reduced C2H2 under the assay conditions suggested that the H2 metabolism traits were associated with various hydrogenase systems rather than with nitrogenase activity

  18. Effect of plant growth promoting micro organisms on increasing water use efficiency of alfalfa in water-stress conditions

    Directory of Open Access Journals (Sweden)

    M. Zafari

    2015-11-01

    Full Text Available In order to study the effect of bacterial growth on water use efficiency of alfalfa, a greenhouse experiment, as factorial based on completely randomized blocks design with three replications, was conducted at Faculty of Agriculture, University of Mohaghegh Ardabili, Ardabil, Iran, in 2012. Treatments consisted of 3 levels of water stress (75, 55 and 35% of field capacity and seed inoculation at 4 levels (no inoculation (control, inoculation with mycorhhiza G. mosseae, inoculation with rhyzobium S. meliloti, and inoculation with combination of mycorhhiza and rhyzobium. Results showed that water stress and seed inoculation have significant effect (P&le0.01 on leaf nutrients content. Water stress reduced absorption of phosphorus (23%, potassium (8%, iron (4% and increased sodium absorption (14% in non-inoculated seeds. Inoculation of seeds reduced stress effects and combined inoculation had the highest effect. Stomatal conductance and water use efficiency were affected (P&le0.01 by inoculation and water stress. Stomatal conductance was decreased during the stress period and seed inoculation with mycorhhiza G. mosseae was most effective on increasing stomatal conductance (47% at the highest level of stress. Water use efficiency increased as a result of water stress and inoculation. The highest value of water use efficiency (0.166 mg/kg was obtained in the combined inoculation with 35% field capacity treatment. Results of regression equations showed that during the inoculation, contribution of phosphorus and potassium in regulation of stomatal conductance was increased and contribution of sodium was decreased.  However, during the stress period, the share of potassium and sodium was increased in stomatal conductance and the share of phosphorus was reduced. Also, stress increased the role of stomatal conductance in water use efficiency. However, inoculation reduced the role of stomatal conductance in water use efficiency.

  19. Sequence and molecular analysis of the nifL gene of Azotobacter vinelandii.

    Science.gov (United States)

    Blanco, G; Drummond, M; Woodley, P; Kennedy, C

    1993-08-01

    In both Klebsiella pneumoniae and Azotobacter vinelandii the nifL gene, which encodes a negative regulator of nitrogen fixation, lies immediately upstream of nifA. We have sequenced the A. vinelandii nifL gene and found that it is more homologous in its C-terminal domain to the histidine protein kinases (HPKs) than is K. pneumoniae NifL. In particular A. vinelandii NifL contains a conserved histidine at a position shown to be phosphorylated in other systems. Both NifL proteins are homologous in their N-termini to a part of the Halobacterium halobium bat gene product; Bat is involved in regulation of bacterio-opsin, the expression of which is oxygen sensitive. The same region showed homology to the haem-binding N-terminal domain of the Rhizobium meliloti fixL gene product, an oxygen-sensing protein. Like K. pneumoniae NifL, A. vinelandii NifL is shown here to prevent expression of nif genes in the presence of NH+4 or oxygen. The sequences found homologous in the C-terminal regions of NifL, FixL and Bat might therefore be involved in oxygen binding or sensing. An in-frame deletion mutation in the nifL coding region resulted in loss of repression by NH+4 and the mutant excreted high amounts of ammonia during nitrogen fixation, thus confirming a phenotype reported earlier for an insertion mutation. In addition, nifLA are cotranscribed in A. vinelandii as in K. pneumoniae, but expression from the A. vinelandii promoter requires neither RpoN nor NtrC. PMID:8231815

  20. The application of isotopic ({sup 32}P and {sup 15}N) dilution techniques to evaluate the interactive effect of phosphate-solubilizing rhizobacteria, mycorrhizal fungi and Rhizobium to improve the agronomic efficiency of rock phosphate for legume crops

    Energy Technology Data Exchange (ETDEWEB)

    Barea, J.M. [Departamento de Microbiologia del Suelo y Sistemas Simbioticos (Spain)]. E-mail: jmbarea@eez.csic.es; Toro, M.; Azcon, R. [Departamento de Microbiologia del Suelo y Sistemas Simbioticos (Spain); Orozco, M.O. [Instituto de Sistematica y Ecologia, Academia Cubana de Ciencias, Habana (Cuba); Campos, E. [Departamento de Ciencias de la Tierra y Quimica Ambiental Estacion Experimental del Zaidin (CSIC), Granada (Spain); Azcon, R. [Departamento de Microbiologia del Suelo y Sistemas Simbioticos (Spain)

    2002-05-15

    A pot experiment was designed to evaluate the interactive effects of multifunctional microbial inoculation treatments and rock phosphate (RP) application on N and P uptake by alfalfa through the use of {sup 15}N and {sup 32}P isotopic dilution approaches. The microbial inocula consisted of a wild type (WT) Rhizobium meliloti strain, the arbuscular mycorrhizal (AM) fungus Glomus mosseae (Nicol. and Gerd.) Gerd. and Trappe, and a phosphate solubilizing rhizobacterium (Enterobacter sp.). Inoculated microorganisms were established in the root tissues and/or in the rhizosphere soil of alfalfa plants (Medicago sativa L.). Improvements in N and P accumulation in alfalfa corroborate beneficial effects of Rhizobium and AM interactions. Inoculation with selected rhizobacteria improved the AM effect on N or P accumulation in both the RP-added soil and in the non RP-amended controls. Measurements of the {sup 15}N/{sup 14}N ratio in plant shoots indicate an enhancement of the N{sub 2} fixation rates in Rhizobium-inoculated AM-plants, over that achieved by Rhizobium in non-mycorrhizal plants. Whether or not RP was added, AM-inoculated plants showed a lower specific activity ({sup 32}P/{sup 31}P) than did their comparable non-mycorrhizal controls, suggesting that the plant was using otherwise unavailable P sources. The phosphate-solubilizing, AM-associated, microbiota could in fact release phosphate ions, either from the added RP or from the indigenous 'less-available' soil phosphate. A low Ca concentrations in the test soil may have benefited P solubilization. Under field conditions, the inoculation with AM fungi significantly increased plant biomass and N and P accumulation in plant tissues. Phosphate-solubilizing rhizobacteria improved mycorrhizal responses in soil dually receiving RP and organic matter amendments. Organic matter addition favoured RP solubilization. This, together with a tailored microbial inoculation, increased the agronomic efficiency of RP in the

  1. The coupling of the plant and microbial catabolisms of phenanthrene in the rhizosphere of Medicago sativa.

    Science.gov (United States)

    Muratova, Anna; Dubrovskaya, Ekaterina; Golubev, Sergey; Grinev, Vyacheslav; Chernyshova, Marina; Turkovskaya, Olga

    2015-09-01

    We studied the catabolism of the polycyclic aromatic hydrocarbon phenanthrene by four rhizobacterial strains and the possibility of enzymatic oxidation of this compound and its microbial metabolites by the root exudates of alfalfa (Medicago sativa L.) in order to detect the possible coupling of the plant and microbial metabolisms under the rhizospheric degradation of the organic pollutant. A comparative study of phenanthrene degradation pathways in the PAH-degrading rhizobacteria Ensifer meliloti, Pseudomonas kunmingensis, Rhizobium petrolearium, and Stenotrophomonas sp. allowed us to identify the key metabolites from the microbial transformation of phenanthrene, including 9,10-phenanthrenequinone, 2-carboxybenzaldehyde, and 1-hydroxy-2-naphthoic, salicylic, and o-phthalic acids. Sterile alfalfa plants were grown in the presence and absence of phenanthrene (0.03 g kg(-1)) in quartz sand under controlled environmental conditions to obtain plant root exudates. The root exudates were collected, concentrated by ultrafiltration, and the activity of oxidoreductases was detected spectrophotometrically by the oxidation rate for various substrates. The most marked activity was that of peroxidase, whereas the presence of oxidase and tyrosinase was detected on the verge of the assay sensitivity. Using alfalfa root exudates as a crude enzyme preparation, we found that in the presence of the synthetic mediator, the plant peroxidase could oxidize phenanthrene and its microbial metabolites. The results indicate the possibility of active participation of plants in the rhizospheric degradation of polycyclic aromatic hydrocarbons and their microbial metabolites, which makes it possible to speak about the coupling of the plant and microbial catabolisms of these contaminants in the rhizosphere. PMID:26398627

  2. The application of isotopic (32P and 15N) dilution techniques to evaluate the interactive effect of phosphate-solubilizing rhizobacteria, mycorrhizal fungi and Rhizobium to improve the agronomic efficiency of rock phosphate for legume crops

    International Nuclear Information System (INIS)

    A pot experiment was designed to evaluate the interactive effects of multifunctional microbial inoculation treatments and rock phosphate (RP) application on N and P uptake by alfalfa through the use of 15N and 32P isotopic dilution approaches. The microbial inocula consisted of a wild type (WT) Rhizobium meliloti strain, the arbuscular mycorrhizal (AM) fungus Glomus mosseae (Nicol. and Gerd.) Gerd. and Trappe, and a phosphate solubilizing rhizobacterium (Enterobacter sp.). Inoculated microorganisms were established in the root tissues and/or in the rhizosphere soil of alfalfa plants (Medicago sativa L.). Improvements in N and P accumulation in alfalfa corroborate beneficial effects of Rhizobium and AM interactions. Inoculation with selected rhizobacteria improved the AM effect on N or P accumulation in both the RP-added soil and in the non RP-amended controls. Measurements of the 15N/14N ratio in plant shoots indicate an enhancement of the N2 fixation rates in Rhizobium-inoculated AM-plants, over that achieved by Rhizobium in non-mycorrhizal plants. Whether or not RP was added, AM-inoculated plants showed a lower specific activity (32P/31P) than did their comparable non-mycorrhizal controls, suggesting that the plant was using otherwise unavailable P sources. The phosphate-solubilizing, AM-associated, microbiota could in fact release phosphate ions, either from the added RP or from the indigenous 'less-available' soil phosphate. A low Ca concentrations in the test soil may have benefited P solubilization. Under field conditions, the inoculation with AM fungi significantly increased plant biomass and N and P accumulation in plant tissues. Phosphate-solubilizing rhizobacteria improved mycorrhizal responses in soil dually receiving RP and organic matter amendments. Organic matter addition favoured RP solubilization. This, together with a tailored microbial inoculation, increased the agronomic efficiency of RP in the test soil that was Ca deficient at neutral p

  3. Auxins upregulate nif and fix genes.

    Science.gov (United States)

    Bianco, Carmen; Defez, Roberto

    2010-10-01

    In a recent publication we analyzed the global effects triggered by IAA overproduction in S. meliloti RD64 under free-living conditions by comparing the gene expression pattern of wild type 1021 with that of RD64 and 1021 treated with IAA and other four chemically or functionally related molecules. Among the genes differentially expressed in RD64 and IAA-treated 1021 cells we found two genes of pho operon, phoT and phoC. Based on this finding we examined the mechanisms for mineral P solubilization in RD64 and the potential ability of this strain to improve Medicago growth under P-starved conditions. Here, we further analyze the expression profiles obtained in microarray analysis and evaluate the specificity and the extent of overlap between all treatments. Venn diagrams indicated that IAA- and 2,4-D-regulated genes were closely related. Furthermore, most differentially expressed genes from pSymA were induced in 1021 cells treated with 2,4-D, ICA, IND and Trp as compared to the untreated 1021 cells. RT-PCR analysis was employed to analyze the differential expression patterns of nitrogen fixation genes under free-living and symbiotic conditions. Under symbiotic condition, the relative expression levels of nif and fix genes were significantly induced in Mt- RD64 plants and in Mt-1021 plants treated with IAA and 2,4-D whereas they were unchanged or repressed in Mt-1021 plants treated with the other selected compounds when compared to the untreated Mt-1021 plants. PMID:20930554

  4. Genetic diversity and community structure of rhizobia nodulating Sesbania cannabina in saline-alkaline soils.

    Science.gov (United States)

    Li, Yan; Li, Xiangyue; Liu, Yajing; Wang, En Tao; Ren, Chenggang; Liu, Wei; Xu, Hualing; Wu, Hailong; Jiang, Nan; Li, Yunzhao; Zhang, Xiaoli; Xie, Zhihong

    2016-05-01

    Sesbania cannabina is a plant that grows naturally along the seashores in Rudong County, China (RDC) and it has been introduced into the Yellow River Delta (YRD) as a pioneer plant to improve the saline-alkaline soils. In order to investigate the diversity of S. cannabina rhizobia in these soils, a total of 198 rhizobial isolates were characterized and phylogenetic trees were constructed based on data from multilocus sequence analysis (MLSA) of the housekeeping genes recA, atpD and glnII, as well as 16S rRNA. Symbiotic features were also studied by establishing the phylogeny of the symbiotic genes nodA and nifH, and by performing nodulation assays. The isolates had highly conserved symbiotic genes and were classified into nine genospecies belonging to the genera Ensifer, Agrobacterium, Neorhizobium and Rhizobium. A unique community structure was detected in the rhizobia associated with S. cannabina in the saline-alkaline soils that was characterized by five novel genospecies and four defined species. In addition, Ensifer sp. I was the predominant rhizobia in YRD, whereas Ensifer meliloti and Neorhizobium huautlense were the dominant species in RDC. Therefore, the study demonstrated for the first time that this plant strongly selected the symbiotic gene background but not the genomic background of its microsymbionts. In addition, biogeographic patterns existed in the rhizobial populations associated with S. cannabina, which were mainly correlated with pH and salinity, as well as the mineral nutrient contents. This study provided novel information concerning the interaction between soil conditions, host plant and rhizobia, in addition to revealing the diversity of S. cannabina rhizobia in saline-alkaline soils. PMID:27061259

  5. Microvirga lupini sp. nov., Microvirga lotononidis sp. nov. and Microvirga zambiensis sp. nov. are alphaproteobacterial root-nodule bacteria that specifically nodulate and fix nitrogen with geographically and taxonomically separate legume hosts.

    Science.gov (United States)

    Ardley, Julie K; Parker, Matthew A; De Meyer, Sofie E; Trengove, Robert D; O'Hara, Graham W; Reeve, Wayne G; Yates, Ron J; Dilworth, Michael J; Willems, Anne; Howieson, John G

    2012-11-01

    Strains of Gram-negative, rod-shaped, non-spore-forming bacteria were isolated from nitrogen-fixing nodules of the native legumes Listia angolensis (from Zambia) and Lupinus texensis (from Texas, USA). Phylogenetic analysis of the 16S rRNA gene showed that the novel strains belong to the genus Microvirga, with ≥ 96.1% sequence similarity with type strains of this genus. The closest relative of the representative strains Lut6(T) and WSM3557(T) was Microvirga flocculans TFB(T), with 97.6-98.0% similarity, while WSM3693(T) was most closely related to Microvirga aerilata 5420S-16(T), with 98.8% similarity. Analysis of the concatenated sequences of four housekeeping gene loci (dnaK, gyrB, recA and rpoB) and cellular fatty acid profiles confirmed the placement of Lut6(T), WSM3557(T) and WSM3693(T) within the genus Microvirga. DNA-DNA relatedness values, and physiological and biochemical tests allowed genotypic and phenotypic differentiation of Lut6(T), WSM3557(T) and WSM3693(T) from each other and from other Microvirga species with validly published names. The nodA sequence of Lut6(T) was placed in a clade that contained strains of Rhizobium, Mesorhizobium and Sinorhizobium, while the 100% identical nodA sequences of WSM3557(T) and WSM3693(T) clustered with Bradyrhizobium, Burkholderia and Methylobacterium strains. Concatenated sequences for nifD and nifH show that the sequences of Lut6(T), WSM3557(T) and WSM3693(T) were most closely related to that of Rhizobium etli CFN42(T) nifDH. On the basis of genotypic, phenotypic and DNA relatedness data, three novel species of Microvirga are proposed: Microvirga lupini sp. nov. (type strain Lut6(T) =LMG 26460(T) =HAMBI 3236(T)), Microvirga lotononidis sp. nov. (type strain WSM3557(T) =LMG 26455(T) =HAMBI 3237(T)) and Microvirga zambiensis sp. nov. (type strain WSM3693(T) =LMG 26454(T) =HAMBI 3238(T)). PMID:22199210

  6. Effect of plant growth promoting rhizobia on seed germination and seedling traits in Acacia senegal

    Directory of Open Access Journals (Sweden)

    Sunil Kumar Singh

    2013-12-01

    Full Text Available Among arid zone tree species, Acacia senegal and Prosopis cineraria are the most important dryland resources of Western Rajasthan desert ecosystem. Due to ecological, biological and molecular similarities, they are often studied together. The climatic conditions in this region restrict the build-up of soil organic matter and soils are generally deficient in nitrogen. Studies were carried out to isolate and molecularly characterize the diverse group of plant growth promoting rhizobacteria from root nodules of native A. senegal and P. cineraria and their effect on seed germination and seedling traits in two genotypes of A. senegal. The direct sequencing of 16S rDNA region resulted in molecular identification of plant growth promoting rhizobacteria as Bacillus licheniformis, Sinorhizobium saheli isolated from root nodules of A. senegal and S. kostiense and S. saheli isolated from root nodules of P. cineraria. The partial sequences of 16S rDNA were assigned Gen accession numbers HQ738496, HQ738499, HQ738506 and HQ738508. Scarification treatment with sulphuric acid (98% for 15 minutes was able to break the exogenous seed dormancy and enhanced germination percentage in control treatment to 90% and 92.5% in A. senegal in genotypes CAZRI 11113AS and CAZRI 35AS, respectively. The treatments with Bacillus licheniformis or S. kostiense, either inoculated individually or as coinoculants, had positive effect on phenotypic traits of germination. Two A. senegal genotypes exhibited significant differences with regard to all the phenotypic traits. On the other hand, treatments with S. saheli isolated from either A. senegal or P. cineraria had negative effects on germination and related phenotypic traits. Values of the coeffivient of determination (R2 over 80% for root length versus shoot length, root/shoot ratio and seedling weight respectively validate that the observed attributes are inter-dependable and linear progression trend can be

  7. Effect of Inoculation of Acacia senegal mature trees with Mycorrhiza and Rhizobia on soil properties and microbial community structure

    Science.gov (United States)

    Assigbetsé, K.; Ciss, I.; Bakhoum, N.; Dieng, L.

    2012-04-01

    Inoculation of legume plants with symbiotic microorganisms is widely used to improve their development and productivity. The objective of this study was to investigate the effect of inoculation of Acacia senegal mature trees with rhizobium (Sinorhizobium) and arbuscular mycorrhizal fungus (G. mosseae, G. fasciculatum, G. intraradices) either singly or in combination, on soil properties, activity and the genetic structure of soil microbial communities. The experiment set up in Southern Senegal consisted of 4 randomized blocks of A. senegal mature trees with 4 treatments including inoculated trees with Rhizobium (R), mycorrhizal fungus (M) and with Rhizobium+mycorhizal fungus (RM) and non-inoculated control (CON). Soil were sampled 2 years after the inoculation. Soil pH, C and N and available P contents were measured. The microbial abundance and activity were measured in terms of microbial biomass C (MBC) and basal soil respiration. The community structure of the total bacterial, diazotrophic and denitrifying communities was assessed by denaturing gradient gel electrophoresis of 16S rDNA, nifH and nirK genes respectively. Inoculations with symbiont under field conditions have increased soil pH. The C and N contents were enhanced in the dual-inoculated treatments (RM). The mycorrhized treatment have displayed the lowest available P contents while RM and R treatments exhibited higher contents rates. The microbial biomass C rates were higher in treatments co-inoculated with AM fungi and Rhizobium than in those inoculated singly with AM fungi or Rhizobium strains. The basal soil respiration were positively correlated to MBC, and the highest rates were found in the co-inoculated treatments. Fingerprints of 16S rDNA gene exhibited similar patterns between inoculated treatments and the control showing that the inoculation of mature trees have not impacted the total bacterial community structure. In contrast, the inoculated treatments have displayed individually different

  8. New Curculionoidea (Coleoptera records for Canadа

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    Hume Douglas

    2013-06-01

    Full Text Available The following species of Curculionoidea are recorded from Canada for the first time, in ten cases also representing new records at the generic level: Ischnopterapion (Ischnopterapion loti (Kirby, 1808; Stenopterapion meliloti (Kirby, 1808 (both Brentidae; Atrichonotus taeniatulus (Berg, 1881; Barinus cribricollis (LeConte, 1876; Caulophilus dubius (Horn, 1873; Cionus scrophulariae (Linnaeus, 1758; Cryptorhynchus tristis LeConte, 1876; Cylindrocopturus furnissi Buchanan, 1940; Cylindrocopturus quercus (Say, 1832; Desmoglyptus crenatus (LeConte, 1876; Pnigodes setosus LeConte, 1876; Pseudopentarthrum parvicollis (Casey, 1892; Sibariops confinis (LeConte, 1876; Sibariops confusus (Boheman, 1836; Smicronyx griseus LeConte, 1876; Smicronyx lineolatus Casey, 1892; Euwallacea validus (Eichhoff, 1875; Hylocurus rudis (LeConte, 1876; Lymantor alaskanus Wood, 1978; Phloeotribus scabricollis (Hopkins, 1916; Scolytus oregoni Blackman, 1934; Xyleborus celsus Eichhoff, 1868; Xyleborus ferrugineus (Fabricius, 1801; Xylosandrus crassiusculus (Motschulsky, 1866 (all Curculionidae. In addition the following species were recorded for the first time from these provinces and territories: Yukon – Dendroctonus simplex LeConte, 1868; Phloetribus piceae Swaine, 1911 (both Curculionidae; Northwest Territories – Loborhynchapion cyanitinctum (Fall, 1927 (Brentidae; Nunavut – Dendroctonus simplex LeConte, 1868 (Curculionidae; Alberta – Anthonomus tectus LeConte, 1876; Promecotarsus densus Casey, 1892; Dendroctonus ponderosae Hopkins, 1902; Hylastes macer LeConte, 1868; Rhyncolus knowltoni (Thatcher, 1940; Scolytus schevyrewi Semenov Tjan-Shansky, 1902 (all Curculionidae; Saskatchewan – Phloeotribus liminaris (Harris, 1852; Rhyncolus knowltoni (Thatcher, 1940; Scolytus schevyrewi Semenov Tjan-Shansky, 1902 (all Curculionidae; Manitoba – Cosmobaris scolopacea Germar, 1819; Listronotus maculicollis (Kirby, 1837; Listronotus punctiger LeConte, 1876; Scolytus