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Sample records for rhizobium etli final

  1. Rhizavidin from Rhizobium etli: the first natural dimer in the avidin protein family

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    Helppolainen, Satu H; Nurminen, Kirsi P; Määttä, Juha AE; Halling, Katrin K.; Slotte, J. Peter; Huhtala, Tuulia; Liimatainen, Timo; Ylä-Herttuala, Seppo; Airenne, Kari J.; Närvänen, Ale; Jänis, Janne; Vainiotalo, Pirjo; Valjakka, Jarkko; Kulomaa, Markku S.; Nordlund, Henri R.

    2007-01-01

    Abstract Rhizobium etli CFN42 is a symbiotic, nitrogen-fixing bacterium of the common bean, Phaseolus vulgaris. The symbiotic plasmid p42d of R. etli comprises a gene encoding a putative (strept)avidin-like protein, named rhizavidin. The amino acid sequence identity of rhizavidin in relation to other known avidin-like proteins is 20-30%. The amino acid residues involved in (strept)avidin-biotin interaction are well conserved in rhizavidin. The structural and functional properties o...

  2. Narrow-Host-Range Bacteriophages That Infect Rhizobium etli Associate with Distinct Genomic Types

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    Santamaría, Rosa Isela; Bustos, Patricia; Sepúlveda-Robles, Omar; Lozano, Luis; Rodríguez, César; Fernández, José Luis; Juárez, Soledad; Kameyama, Luis; Guarneros, Gabriel; Dávila, Guillermo; González, Víctor

    2014-01-01

    In this work, we isolated and characterized 14 bacteriophages that infect Rhizobium etli. They were obtained from rhizosphere soil of bean plants from agricultural lands in Mexico using an enrichment method. The host range of these phages was narrow but variable within a collection of 48 R. etli strains. We obtained the complete genome sequence of nine phages. Four phages were resistant to several restriction enzymes and in vivo cloning, probably due to nucleotide modifications. The genome si...

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

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

    1997-01-01

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

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

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

    2000-01-01

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

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

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

    2011-01-01

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

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

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    González Víctor

    2011-10-01

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

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

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    Reina-Bueno Mercedes

    2012-09-01

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

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

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

    2011-01-01

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

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

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    Mendoza-Hernández Guillermo

    2010-10-01

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

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

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    Beullens Serge

    2008-12-01

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

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

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

    2009-01-01

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

  12. High salt and high pH tolerance of new isolated Rhizobium etli strains from Egyptian soils.

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    Shamseldin, Abdelaal; Werner, Dietrich

    2005-01-01

    Saline and alkaline soils are major problems contributing to the low productivity of common bean (Phaseolus vulgaris) in arid and semi-arid regions such as Egypt. Therefore our study was directed toward selecting strains more tolerant to these environmental stresses. Among seven Rhizobium etli strains isolated from Egyptian soils, we found a high degree of diversity. Strains EBRI 21 and EBRI 26 are highly tolerant to a salt concentration up to 4% NaCl. A positive correlation was found between the salt tolerance and the adaptation to alkaline pH (9). Strains EBRI 2 and EBRI 26 were adapted to elevated temperatures (42 degrees C). The minimum level of low pH for the majority of Rhizobium etli strains from Egypt was pH 4.7 while the Colombian strain Rhizobium tropici CIAT 899 survived well at pH 4. At 0.4% NaCl, the symbiotic efficiency of the salt-tolerant strain EBRI 26 was superior in cultivar Giza 6 compared with the salt-sensitive strain EBRI 2 (18.2 compared with 13.9 nM: C2H4 h(-1) mg(-1) nodule fresh weight). In the bean cultivar Saxa, nitrogen fixation was much more affected by high salt concentration (0.4% NaCl) than in the cultivar Giza 6 with both strains (3.9 and 3.8 nM: C2H4 h(-1) mg(-1) nodule fresh weight, respectively). In general, stress of alkalinity had a less detrimental effect on nodulation and N2 fixation than stress of salinity. PMID:15702257

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

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

    2010-01-01

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

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

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

    2008-04-01

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

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

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

    1999-01-01

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

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

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

    2012-10-30

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

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

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

    2015-10-01

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

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

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

    2010-05-01

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

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

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

    2010-07-01

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

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

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

    2003-01-01

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

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

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    Bulakali, B.

    1999-01-01

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

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

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

    1999-01-01

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

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

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

    1992-01-01

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

  4. Enhanced nitrogen fixation in a Rhizobium etli ntrC mutant that overproduces the Bradyrhizobium japonicum symbiotic terminal oxidase cbb{sub 3}

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    Soberon, M.; Lopez, O.; Morera, C.; Girard, M.L.; Tabche, M.L.; Miranda, J. [Univ. Nacional Autonoma de Mexico, Cuernavaca (Mexico)

    1999-05-01

    The ntrC gene codes for a transcriptional activator protein that modulates gene expression in response to nitrogen. The cytochrome production pattern of a Rhizobium etli ntrC mutant (CFN2012) was studied. CO difference spectral analysis of membranes showed that CFN2012 produced a terminal oxidase similar to the symbiotic terminal oxidase of bacteroids in free-living cells under aerobic conditions, with a characteristic trough at 553 nm. CFN2012 produced two c-type cytochromes with molecular masses of 27 and 32 kDa in contrast with the wild-type strain, which produced only a 32-kDa c-tye cytochrome. The expression levels of the R. etli fix/NOQP operon, which codes for terminal oxidase cbb{sub 3}, were not affected by the ntrC mutation. However, the production levels of the two c-type cytochromes (27 and 32 kDa) were enhanced at least eightfold when the Bradyrhizobium japonicum fixNOQP operon was expressed in CFN2012 from the nptII promoter (pMSfix{sup c}), suggesting that these proteins are subunits FixO (27 kDa) and FixP (32 kDa) of cbb{sub 3} and that CFN2012/pMSfix{sup c} overproduced this terminal oxidase. CFN2012/pMSfix{sup c} showed a significant increase in its symbiotic performance as judged by the determination of nitrogenase activities of plants inoculated with this strain, suggesting that the overproduction of cbb{sub 3} terminal oxidase correlates with an enhancement in symbiotic nitrogen fixation.

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

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

    2015-05-01

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

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

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    F. M. Mercante

    2000-06-01

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

  7. Regulation of tryptophan genes in Rhizobium leguminosarum.

    OpenAIRE

    Holmgren, E; Crawford, I. P.

    1982-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Lachaâl M.

    2009-01-01

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

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

    Science.gov (United States)

    Lunak, Zachary R; Dale Noel, K

    2015-09-01

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

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

    Science.gov (United States)

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

    2015-09-01

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

  11. 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.

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

    Science.gov (United States)

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

    2015-08-01

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

  13. Expression Cloning and Characterization of the C28 Acyltransferase of Lipid A Biosynthesis in Rhizobium leguminosarum*

    OpenAIRE

    Basu, Shib Sankar; Karbarz, Mark J.; Raetz, Christian R H

    2002-01-01

    An unusual feature of lipid A from plant endosymbionts of the Rhizobiaceae family is the presence of a 27-hydroxyoctacosanoic acid (C28) moiety. An enzyme that incorporates this acyl chain is present in extracts of Rhizobium leguminosarum, Rhizobium etli, and Sinorhizobium meliloti but not Escherichia coli. The enzyme transfers 27-hydroxyoctacosanate from a specialized acyl carrier protein (AcpXL) to the precursor Kdo2 ((3-deoxy-D-manno-octulosonic acid)2)-lipid IVA. We now report the identif...

  14. Physiology of the Rhizobium-legume association

    International Nuclear Information System (INIS)

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

  15. 76 FR 5439 - United States, et al. v. Comcast Corp., et al.; Proposed Final Judgment and Competitive Impact...

    Science.gov (United States)

    2011-01-31

    ..., subject to Comcast's right to purchase at fair market value any interest that GE proposes to sell... Nielsen ratings, which distributors and advertisers use as a proxy for a network's value. The importance...., et al.; Proposed Final Judgment and Competitive Impact Statement; Notice #0;#0;Federal Register /...

  16. 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

  17. : Les Struthionidae et les Pelagornithidae (Aves, Struthioniformes et Odontopterygiformes) du Pliocène final d'Ahl al Oughlam, Maroc

    OpenAIRE

    Mourer-Chauviré, Cécile; Geraads, Denis

    2005-01-01

    Le gisement pliocène d'Ahl al Oughlam est situé à la limite sud-est de la ville de Casablanca, au Maroc, sur un ancien rivage de l'Océan Atlantique. Il a livré une très riche faune de Vertébrés (macro- et micromammifères, oiseaux, reptiles, amphibiens et poissons), appartenant surtout à des formes terrestres, mais comportant aussi des formes marines. Des arguments biostratigraphiques ont permis de dater cette faune de 2,5 Ma, ce qui correspond au Pliocène final. L'avifaune est très diversifié...

  18. Polyol metabolism by Rhizobium trifolii.

    OpenAIRE

    Primrose, S B; Ronson, C W

    1980-01-01

    In Rhizobium trifolii 7000, the polyols myo-inositol, xylitol, ribitol, D-arabitol, D-mannitol, D-sorbital, and dulcitol are metabolized by inducible nicotinamide adenine dinucleotide-dependent polyol dehydrogenases. Five different polyol dehydrogenases were recognized: inositol dehydrogenase, specific for inositil; ribitol dehydrogenase, specific for ribitol; D-arabitol dehydrogenase, which oxidized D-arabitol, D-mannitol, and D-sorbitol; xylitol dehydrogenase, which oxidized xylitol and D-s...

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

    CERN Document Server

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

    2008-01-01

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

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

    Science.gov (United States)

    Tesfaye, M; Holl, F B

    1998-11-01

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

  1. 78 FR 22298 - United States v. Apple, Inc., et al.; Public Comments and Response on Proposed Final Judgment

    Science.gov (United States)

    2013-04-15

    ..., see United States v. Apple, Inc., et al., 77 FR 77094; and summaries of the terms of the proposed... Antitrust Division United States v. Apple, Inc., et al.; Public Comments and Response on Proposed Final... States v. Apple, Inc., et al., Civil Action No. 12-CV-2826 (DLC), which was filed in the United...

  2. Evolutionary origin of rhizobium Nod factor signaling

    OpenAIRE

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

    2011-01-01

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

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

    OpenAIRE

    Bedmar, E. J.; 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.

  4. Reclassification of Rhizobium tropici type A strains as Rhizobium leucaenae sp. nov.

    Science.gov (United States)

    Ribeiro, Renan Augusto; Rogel, Marco A; López-López, Aline; Ormeño-Orrillo, Ernesto; Barcellos, Fernando Gomes; Martínez, Julio; Thompson, Fabiano Lopes; Martínez-Romero, Esperanza; Hungria, Mariangela

    2012-05-01

    Rhizobium tropici is a well-studied legume symbiont characterized by high genetic stability of the symbiotic plasmid and tolerance to tropical environmental stresses such as high temperature and low soil pH. However, high phenetic and genetic variabilities among R. tropici strains have been largely reported, with two subgroups, designated type A and B, already defined within the species. A polyphasic study comprising multilocus sequence analysis, phenotypic and genotypic characterizations, including DNA-DNA hybridization, strongly supported the reclassification of R. tropici type A strains as a novel species. Type A strains formed a well-differentiated clade that grouped with R. tropici, Rhizobium multihospitium, Rhizobium miluonense, Rhizobium lusitanum and Rhizobium rhizogenes in the phylogenies of the 16S rRNA, recA, gltA, rpoA, glnII and rpoB genes. Several phenotypic traits differentiated type A strains from all related taxa. The novel species, for which the name Rhizobium leucaenae sp. nov. is proposed, is a broad host range rhizobium being able to establish effective root-nodule symbioses with Leucaena leucocephala, Leucaena esculenta, common beans (Phaseolus vulgaris) and Gliricidia sepium. Strain CFN 299(T) (?=?USDA 9039(T)?=?LMG 9517(T)?=?CECT 4844(T)?=?JCM 21088(T)?=?IAM 14230(T)?=?SEMIA 4083(T)?=?CENA 183(T)?=?UMR1026(T)?=?CNPSo 141(T)) is designated the type strain of Rhizobium leucaenae sp. nov. PMID:21742822

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

    OpenAIRE

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

    1998-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Stéphane Legrand

    2004-04-01

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

  7. 77 FR 44271 - United States v. Apple, Inc., et al.; Public Comments and Response on Proposed Final Judgment

    Science.gov (United States)

    2012-07-27

    ...JUSTICE Antitrust Division United States v. Apple, Inc., et al.; Public Comments and...proposed Final Judgment in United States v. Apple, Inc., et al., Civil Action No. 12-CV-2826...www.justice.gov/atr/cases/apple/index.html. A copy of the United...

  8. 77 FR 44271 - United States v. Apple, Inc., et al.; Public Comments and Response on Proposed Final Judgment

    Science.gov (United States)

    2012-07-27

    ... Judgment and CIS were published in the Federal Register on April 24, 2012, at 77 FR 24518; and summaries of... Antitrust Division United States v. Apple, Inc., et al.; Public Comments and Response on Proposed Final... United States v. Apple, Inc., et al., Civil Action No. 12-CV-2826 (DLC), which was filed in the...

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

    Science.gov (United States)

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

    2015-09-01

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

  10. Production of Exo-polysaccharide by Rhizobium sp.

    OpenAIRE

    Sayyed, R. Z.; Jamadar, D. D.; P. R. Patel

    2011-01-01

    Two fold increase in the yield of glucose and maltose containing exo-polysaccharide (EPS) by Rhizobium sp. was observed during its growth in modified YEMB. EPS production, plant growth promotion activity and root colonization of Rhizobium sp. studies showed enhanced EPS synthesis, more seed germination and over all improvement in plant growth over control and R. meliloti treatment. Groundnut seeds bacterized with Rhizobium sp. resulted in 69.75% more root length, 49.51% more shoot height, 13....

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

    OpenAIRE

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

    1984-01-01

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

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

    OpenAIRE

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

    2014-01-01

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

  13. Evolutionary origin of rhizobium Nod factor signaling.

    Science.gov (United States)

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

    2011-10-01

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

  14. Conservation between coding and regulatory elements of Rhizobium meliloti and Rhizobium leguminosarum dct genes.

    OpenAIRE

    Jiang, J.; Gu, B H; Albright, L M; Nixon, B T

    1989-01-01

    Complementation of Rhizobium leguminosarum dct mutants with a cosmid bank yielded Rhizobium meliloti homologs of the dctA, dctB, and dctD genes. The genes dctB and dctD are thought to form a two-component system which responds to the presence of C4-dicarboxylates to regulate expression of a transport protein encoded by dctA. DNA sequence analysis showed that dct coding and intergenic regions, including putative binding sites for the dctD protein and sigma 54-RNA polymerase, were highly conser...

  15. 75 FR 33637 - United States v. Bemis Company, Inc., et al.; Public Comments and Response on Proposed Final...

    Science.gov (United States)

    2010-06-14

    .... Bemis Company, Inc. et al., 75 FR 9929; and published summaries of the terms of the proposed Final... remedies, its perception of the market structure, and its views of the nature of the case). \\4\\ Cf. BNS... others can not use them. There is bitterness throughout the plant and unrespectable and...

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

    DEFF Research Database (Denmark)

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

    1986-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Del Bel Kate L

    2003-01-01

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

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

    Science.gov (United States)

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

    2005-11-01

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

  19. 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...

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

    Energy Technology Data Exchange (ETDEWEB)

    Hollingsworth, R.I.

    1991-01-01

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

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

    OpenAIRE

    Ben Khaled, Laaziza; Gõmez, Asun?ion; Honrubia, Mario; Oihabi, Abdallah

    2003-01-01

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

  2. Cloning of the glutamine synthetase I gene from Rhizobium meliloti.

    OpenAIRE

    Somerville, J E; Kahn, M L

    1983-01-01

    Glutamine synthetase is a major enzyme in the assimilation of ammonia by members of the genus Rhizobium. Two forms of glutamine synthetase are found in members of the genus Rhizobium, a heat-stable glutamine synthetase I (GSI) and a heat-labile GSII. As a step toward clarifying the role of these enzymes in symbiotic nitrogen fixation, we have cloned the structural gene for GSI from Rhizobium meliloti 104A14. A gene bank of R. meliloti was constructed by using the bacteriophage P4 cosmid pMK31...

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

    OpenAIRE

    Abdullah M. K. Al-Falih

    2002-01-01

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

  4. Variability among Rhizobium Strains Originating from Nodules of Vicia faba

    OpenAIRE

    van Berkum, P.; Beyene, D; Vera, F. T.; Keyser, H H

    1995-01-01

    Rhizobium strains from nodules of Vicia faba were diverse in plasmid content and serology. Results of multilocus gel electrophoresis and restriction fragment length polymorphism indicated several deep chromosomal lineages among the strains. Linkage disequilibrium among the chromosomal types was detected and may have reflected variation of Rhizobium strains in the different geographical locations from which the strains originated. An investigation of pea strains with antibodies prepared agains...

  5. 76 FR 81528 - United States v. Exelon Corporation, et al.; Proposed Final Judgment and Competitive Impact...

    Science.gov (United States)

    2011-12-28

    ...conduct prohibited by the antitrust laws may bring suit in federal...bringing of any private antitrust damage action. Under...2011. Description: Antitrust. Proposed Final Judgment...any issue of fact or law, and without this...

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

    OpenAIRE

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

    2008-01-01

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

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

    Science.gov (United States)

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

    2015-12-01

    A Gram-stain-negative, non-spore-forming, rod-shaped and aerobic bacterium, designated Xi19T, was isolated from a soil sample collected from the rhizosphere of sunflower (Helianthus annuus) in Wuyuan county of Inner Mongolia, China and was characterized taxonomically by using a polyphasic approach. Phylogenetic analysis based on 16S rRNA gene sequences indicated that the novel isolate was related to species of the genus Rhizobium, sharing the greatest 16S rRNA gene sequence similarity with Rhizobium rhizoryzae J3-AN59T (98.4?%), followed by Rhizobium pseudoryzae J3-A127T (97.4?%). There were low similarities (?Rhizobium. DNA-DNA hybridization values between strain Xi19T and the most related strain Rhizobium rhizoryzae J3-AN59T were low. The major cellular fatty acids of strain Xi19T were C16?:?0, summed feature 8 (C18?:?1?7c and/or C18?:?1?6c) and C19?:?0 cyclo ?8c. Q-10 was identified as the predominant ubiquinone and the major polar lipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine and phosphatidylcholine. The DNA G+C content of strain Xi19T was 60.2?mol%. On the basis of physiological and biochemical characteristics, coupled with genotypic data obtained in this work, strain Xi19T represents a novel species of the genus Rhizobium, for which the name Rhizobium helianthi is proposed. The type strain is Xi19T (?=?CGMCC 1.12192T?=?KCTC 23879T). PMID:26364048

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

    Directory of Open Access Journals (Sweden)

    Lin, XG.

    1993-01-01

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

  9. Production of Exo-polysaccharide by Rhizobium sp.

    Science.gov (United States)

    Sayyed, R Z; Jamadar, D D; Patel, P R

    2011-07-01

    Two fold increase in the yield of glucose and maltose containing exo-polysaccharide (EPS) by Rhizobium sp. was observed during its growth in modified YEMB. EPS production, plant growth promotion activity and root colonization of Rhizobium sp. studies showed enhanced EPS synthesis, more seed germination and over all improvement in plant growth over control and R. meliloti treatment. Groundnut seeds bacterized with Rhizobium sp. resulted in 69.75% more root length, 49.51% more shoot height, 13.75% more number of branches and 13.60% more number of pods over the control and R. meliloti treatment. Bacterization of wheat seeds increased the dry matter yield of roots (1.7-fold), and roots adhering soil (RAS) (1.5) and shoot mass (1.9-fold). Rhizobium sp. inoculation also increased the population density of EPS-producing bacteria on the rhizoplane. Roots of plants inoculated with Rhizobium sp. maintained a higher K(+)/Na(+) ratio and K(+)-Na(+) selectivity. PMID:22754006

  10. Physiological role of calcium in legume-rhizobium symbiosis

    Directory of Open Access Journals (Sweden)

    Vasil’eva G.G.

    2011-12-01

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

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

    Science.gov (United States)

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

    2015-01-01

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

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

    Science.gov (United States)

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

    2015-02-01

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

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

    OpenAIRE

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

    1985-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Antonio Roberto Giardini

    1985-01-01

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

  15. A rhizobium selenitireducens protein showing selenite reductase activity

    Science.gov (United States)

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

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

    Science.gov (United States)

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

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

    Science.gov (United States)

    Kittiwongwattana, Chokchai; Thawai, Chitti

    2014-07-01

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

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

    Science.gov (United States)

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

    2015-04-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Hollingsworth, R.I.

    1991-12-31

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

  20. Isolation and expression of Rhizobium japonicum cloned DNA encoding an early soybean nodulation function.

    OpenAIRE

    Sutton, B.C.; Stanley,J.; Zelechowska, M G; Verma, D P

    1984-01-01

    A first visible step in the nodulation of legumes by Rhizobium spp. is the deformation and curling of root hairs. We have identified and cloned DNA sequences encoding this function from two strains of Rhizobium japonicum (USDA 122 and USDA 110) with a weakly homologous probe from Rhizobium meliloti. Root hair curling encoded by the cloned DNA fragments was examined on soybeans (Glycine soja ) after conjugative transfer of these sequences in broad-host-range vectors to various bacterial genera...

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

    Directory of Open Access Journals (Sweden)

    Cigdem KuCuk

    2008-01-01

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

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

    OpenAIRE

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

    1990-01-01

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

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

    OpenAIRE

    Plazinski, Jacek; Rolfe, Barry G.

    1985-01-01

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

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

    OpenAIRE

    Sri Purwaningsih*

    2009-01-01

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

  5. Expression Cloning and Characterization of the C28 Acyltransferase of Lipid A Biosynthesis in Rhizobium leguminosarum*

    Science.gov (United States)

    Basu, Shib Sankar; Karbarz, Mark J.; Raetz, Christian R. H.

    2008-01-01

    An unusual feature of lipid A from plant endosymbionts of the Rhizobiaceae family is the presence of a 27-hydroxyoctacosanoic acid (C28) moiety. An enzyme that incorporates this acyl chain is present in extracts of Rhizobium leguminosarum, Rhizobium etli, and Sinorhizobium meliloti but not Escherichia coli. The enzyme transfers 27-hydroxyoctacosanate from a specialized acyl carrier protein (AcpXL) to the precursor Kdo2 ((3-deoxy-D-manno-octulosonic acid)2)-lipid IVA. We now report the identification of five hybrid cosmids that direct the overexpression of this activity by screening ~4000 lysates of individual colonies of an R. leguminosarum 3841 genomic DNA library in the host strain S. meliloti 1021. In these heterologous constructs, both the C28 acyltransferase and C28-AcpXL are overproduced. Sequencing of a 9-kb insert from cosmid pSSB-1, which is also present in the other cosmids, shows that acpXL and the lipid A acyltransferase gene (lpxXL) are close to each other but not contiguous. Nine other open reading frames around lpxXL were also sequenced. Four of them encode orthologues of fatty acid and/or polyketide bio-synthetic enzymes. AcpXL purified from S. meliloti expressing pSSB-1 is fully acylated, mainly with 27-hydroxyoctacosanoate. Expression of lpxXL in E. coli behind a T7 promoter results in overproduction in vitro of the expected R. leguminosarum acyltransferase, which is C28-AcpXL-dependent and utilizes (3-deoxy-D-manno-octulosonic acid)2-lipid IVA as the acceptor. These findings confirm that lpxXL is the structural gene for the C28 acyltransferase. LpxXL is distantly related to the lauroyltransferase (LpxL) of E. coli lipid A biosynthesis, but highly significant LpxXL orthologues are present in Agrobacterium tumefaciens, Brucella melitensis, and all sequenced strains of Rhizobium, consistent with the occurrence of long secondary acyl chains in the lipid A molecules of these organisms. PMID:12019272

  6. 78 FR 33437 - United States v. Apple, Inc., et al.; Public Comments and Response on Proposed Final Judgment

    Science.gov (United States)

    2013-06-04

    ...JUSTICE Antitrust Division United States v. Apple, Inc., et al.; Public Comments and...b/a Macmillan in United States v. Apple, Inc., et al., Civil Action No. 12-CV-2826...www.justice.gov/atr/cases/apple/index-2.html, and at the...

  7. 78 FR 22298 - United States v. Apple, Inc., et al.; Public Comments and Response on Proposed Final Judgment

    Science.gov (United States)

    2013-04-15

    ...JUSTICE Antitrust Division United States v. Apple, Inc., et al.; Public Comments and...Group (USA), Inc. in United States v. Apple, Inc., et al., Civil Action No. 12-CV-2826...www.justice.gov/atr/cases/apple/index-1.html, and at the...

  8. Impact of heavy metals on an arctic rhizobium

    Energy Technology Data Exchange (ETDEWEB)

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

    1991-03-01

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

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

    Science.gov (United States)

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

    1994-07-01

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

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

    Science.gov (United States)

    Abril, A; González, C

    1994-01-01

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

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

    OpenAIRE

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

    1984-01-01

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

  12. Polysaccharide synthesis in relation to nodulation behavior of Rhizobium leguminosarum.

    OpenAIRE

    Breedveld, M.W.; Cremers, H C; Batley, M.; Posthumus, M.A.; Zevenhuizen, L P; Wijffelman, C. A.; Zehnder, A J

    1993-01-01

    In this study, we characterized four Tn5 mutants derived from Rhizobium leguminosarum RBL5515 with respect to synthesis and secretion of cellulose fibrils, extracellular polysaccharides (EPS), capsular polysaccharides, and cyclic beta-(1,2)-glucans. One mutant, strain RBL5515 exo-344::Tn5, synthesizes residual amounts of EPS, the repeating unit of which lacks the terminal galactose molecule and the substituents attached to it. On basis of the polysaccharide production pattern of strain RBL551...

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

    OpenAIRE

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

    2013-01-01

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

  14. Transport and catabolism of D-mannose in Rhizobium meliloti.

    OpenAIRE

    Arias, A.; Gardiol, A; Martínez-Drets, G

    1982-01-01

    Rhizobium meliloti L5-30 grows on D-mannose as the sole carbon source. The catabolic pathway of D-mannose was characterized. The following activities were present: mannose transport system, mannokinase, and mannosephosphate isomerase. Several mannose-negative mutants were selected; they were classified into three functional groups: group I, mannokinase and mannosephosphate isomerase defective: group II, mannokinase defective; and group III, mannosephosphate isomerase defective. Mannose uptake...

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

    OpenAIRE

    Munévar, Fernando; Wollum, Arthur G.

    1981-01-01

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

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

    OpenAIRE

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

    1980-01-01

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

  17. Dechlorination of Atrazine by a Rhizobium sp. Isolate

    OpenAIRE

    Bouquard, C.; Ouazzani, J.; Prome, J.; Michel-Briand, Y.; Plesiat, P.

    1997-01-01

    A Rhizobium sp. strain, named PATR, was isolated from an agricultural soil and found to actively degrade the herbicide atrazine. Incubation of PATR in a basal liquid medium containing 30 mg of atrazine liter(sup-1) resulted in the rapid consumption of the herbicide and the accumulation of hydroxyatrazine as the only metabolite detected after 8 days of culture. Experiments performed with ring-labeled [(sup14)C]atrazine indicated no mineralization. The enzyme responsible for the hydroxylation o...

  18. 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...

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

    Science.gov (United States)

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

    1975-06-01

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

  20. Rhizobium pongamiae sp. nov. from root nodules of Pongamia pinnata.

    Science.gov (United States)

    Kesari, Vigya; Ramesh, Aadi Moolam; Rangan, Latha

    2013-01-01

    Pongamia pinnata has an added advantage of N2-fixing ability and tolerance to stress conditions as compared with other biodiesel crops. It harbours "rhizobia" as an endophytic bacterial community on its root nodules. A gram-negative, nonmotile, fast-growing, rod-shaped, bacterial strain VKLR-01(T) was isolated from root nodules of Pongamia that grew optimal at 28°C, pH 7.0 in presence of 2% NaCl. Isolate VKLR-01 exhibits higher tolerance to the prevailing adverse conditions, for example, salt stress, elevated temperatures and alkalinity. Strain VKLR-01(T) has the major cellular fatty acid as C(18:1) ?7c (65.92%). Strain VKLR-01(T) was found to be a nitrogen fixer using the acetylene reduction assay and PCR detection of a nifH gene. On the basis of phenotypic, phylogenetic distinctiveness and molecular data (16S rRNA, recA, and atpD gene sequences, G + C content, DNA-DNA hybridization etc.), strain VKLR-01(T) = (MTCC 10513(T) = MSCL 1015(T)) is considered to represent a novel species of the genus Rhizobium for which the name Rhizobium pongamiae sp. nov. is proposed. Rhizobium pongamiae may possess specific traits that can be transferred to other rhizobia through biotechnological tools and can be directly used as inoculants for reclamation of wasteland; hence, they are very important from both economic and environmental prospects. PMID:24078904

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

    Science.gov (United States)

    Kaur, Jaspreet; Verma, Mansi; Lal, Rup

    2011-05-01

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

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

    Science.gov (United States)

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

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

    Science.gov (United States)

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

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

    International Nuclear Information System (INIS)

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

  5. 76 FR 68210 - United States v. George's Foods, LLC, et al.; Public Comment and Response on Proposed Final Judgment

    Science.gov (United States)

    2011-11-03

    ... United States v. George's Foods, Inc., et. al., 76 FR 38419; and summaries of the terms of the proposed... received only one comment, co-authored by attorney David A. Balto and law professor Peter C. Carstensen.... Harkrider, Rachel J. Adcox, Russell M. Steinthal, Axinn, Veltrop & Harkrider LLP, 114 West 47th Street,...

  6. 76 FR 55111 - United States v. General Electric Co., et al.; Proposed Final Judgment and Competitive Impact...

    Science.gov (United States)

    2011-09-06

    ... United States of America v. General Electric Co., et al., Civil Action No. 1:11-cv-01549. On August 29... Civil Enforcement. United States District Court for the District of Columbia United States of America... United States of America (``United States''), acting under the direction of the Attorney General of...

  7. 78 FR 33437 - United States v. Apple, Inc., et al.; Public Comments and Response on Proposed Final Judgment

    Science.gov (United States)

    2013-06-04

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

  8. Transformation of Rhizobium meliloti 41 with plasmid DNA.

    OpenAIRE

    Kiss, G B; Kálmán, Z

    1982-01-01

    Plasmid pGV1106, a derivative of the wide-host-range plasmid S-a of the W incompatibility group, was introduced into Rhizobium meliloti 41 by plasmid-mediated mobilization to overcome the restriction of foreign DNA. The mobilized plasmid pKK2 differed from the original pGV1106 by an extra piece of DNA of 1.3 kilobase pairs which supposedly originated from pJB3JI used for mobilization. If pKK2 was isolated from R. meliloti 41, it could be successfully reintroduced by transformation. The transf...

  9. Relations between Rhizobium and radiostimulation treatments of seeds

    International Nuclear Information System (INIS)

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

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

    DEFF Research Database (Denmark)

    Engvild, Kjeld Christensen; Nielsen, G.

    1985-01-01

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

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

    OpenAIRE

    Gardiol, A; Arias, A.; C. Cerveñansky; 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. 75 FR 9929 - United States v. Bemis Company, Inc., et al.; Proposed Final Judgment and Competitive Impact...

    Science.gov (United States)

    2010-03-04

    ..., Wisconsin and Catoosa, Oklahoma, as well as certain other tangible and intangible assets. The proposed Final... limited to, all real property and improvements, manufacturing equipment, product inventory, tooling and fixed assets, personal property, titles, interests, leases, input inventory, office furniture,...

  13. 76 FR 28080 - United States v. Unilever N.V., et al.; Proposed Final Judgment and Competitive Impact Statement

    Science.gov (United States)

    2011-05-13

    ...conduct prohibited by the antitrust laws may bring suit in Federal...bringing of any private antitrust damage action. Under...2011 DESCRIPTION: Antitrust [PROPOSED] FINAL JUDGMENT...any issue of fact or law, and without this...

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

    Directory of Open Access Journals (Sweden)

    Ni Made Widyasari

    2015-02-01

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

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

    Science.gov (United States)

    Tiwari, Shreekant; Beriha, Siba Shanker

    2015-10-01

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

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

    Directory of Open Access Journals (Sweden)

    Rahat Parveen

    1999-01-01

    Full Text Available Two chickpea varieties viz., 90122 and 93081 were subjected to Rhizobium inoculation with BioPower under water stress conditions, imposed by withholding water. Stress reduced all the parameters including yield components and this effect was more pronounced by stress at reproductive stage as compared with vegetative stage. Rhizobium inoculation enhanced yield under both normal and stressed conditions, but its performance was better under normal than under stress. Rhizobium inoculation proved ineffective to recover loss caused by water stress. The two varieties exhibited statistically non-significant differences.

  17. A rhizobium leguminosarum mutant defective in symbiotic iron acquisition

    International Nuclear Information System (INIS)

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

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

    Science.gov (United States)

    Paau, A; Cowles, J R

    1975-10-01

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

  19. Microgravity effects on the legume/Rhizobium symbiosis

    Science.gov (United States)

    Urban, James E.

    1997-01-01

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

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

    Science.gov (United States)

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

    2009-03-01

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

  1. 76 FR 21006 - United States and State of New York v. Stericycle, Inc., et al.; Proposed Final Judgment and...

    Science.gov (United States)

    2011-04-14

    ... will have knowledge in advance of acquisitions that may impact competition in the provision of... whereas, the essence of this Final Judgment is the prompt and certain divestiture of the Divestiture Asset... at any time prior to the Court's entry of judgment. The comments and the response of the...

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

    Directory of Open Access Journals (Sweden)

    Antonio Roberto Giardini

    1984-01-01

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

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

    International Nuclear Information System (INIS)

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2009-07-01

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

  5. Rhizobium lipopolysaccharide modulates infection thread development in white clover root hairs.

    OpenAIRE

    Dazzo, F. B.; Truchet, G L; Hollingsworth, R. I.; Hrabak, E M; Pankratz, H. S.; Philip-Hollingsworth, S; Salzwedel, J L; Chapman, K; Appenzeller, L; Squartini, A

    1991-01-01

    The interaction between Rhizobium lipopolysaccharide (LPS) and white clover roots was examined. The Limulus lysate assay indicated that Rhizobium leguminosarum bv. trifolii (hereafter called R. trifolii) released LPS into the external root environment of slide cultures. Immunofluorescence and immunoelectron microscopy showed that purified LPS from R. trifolii 0403 bound rapidly to root hair tips and infiltrated across the root hair wall. Infection thread formation in root hairs was promoted b...

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

    OpenAIRE

    Huala, E.; Stigter, J (Hans) de; 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.

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

    Science.gov (United States)

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

    2016-01-01

    Two Gram-negative, aerobic, non-motile, rod-shaped bacterial strains, FH13T and FH23, representing a novel group of Rhizobium isolated from root nodules of Phaseolus vulgaris in Mexico, were studied by a polyphasic analysis. Phylogeny of 16S rRNA gene sequences revealed them to be members of the genus Rhizobium related most closely to 'Rhizobium anhuiense' CCBAU 23252 (99.7?% similarity), Rhizobium leguminosarum USDA 2370T (98.6?%), and Rhizobium sophorae CCBAU 03386T and others (???98.3?%). In sequence analyses of the housekeeping genes recA, glnII and atpD, both strains formed a subclade distinct from all defined species of the genus Rhizobium at sequence similarities of 82.3-94.0?%, demonstrating that they represented a novel genomic species in the genus Rhizobium. Mean levels of DNA-DNA relatedness between the reference strain FH13T and the type strains of related species varied between 13.0?±?2.0 and 52.1?±?1.2?%. The DNA G+C content of strain FH13T was 63.5?mol% (Tm). The major cellular fatty acids were 16?:?0, 17?:?0 anteiso, 18?:?0, summed feature 2 (12?:?0 aldehyde/unknown 10.928) and summed feature 8 (18?:?1?7c). The fatty acid 17?:?1?5c was unique for this strain. Some phenotypic features, such as failure to utilize adonitol, l-arabinose, d-fructose and d-fucose, and ability to utilize d-galacturonic acid and itaconic acid as carbon source, could also be used to distinguish strain FH13T from the type strains of related species. Based upon these results, a novel species, Rhizobium acidisoli sp. nov., is proposed, with FH13T (?=?CCBAU 101094T?=?HAMBI 3626T?=?LMG 28672T) as the type strain. PMID:26530784

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

    OpenAIRE

    Schetgens, T.M.P.

    1986-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Araújo Ademir Sérgio Ferreira de

    2006-01-01

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

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

    Science.gov (United States)

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

    2011-11-01

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

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

    Directory of Open Access Journals (Sweden)

    Eny Fuskhah

    2014-04-01

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

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

    OpenAIRE

    Rahat Parveen; Sadiq, M.; Muzammil Saleem

    1999-01-01

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

  13. New nonsynthetic medium for Rhizobium culture production from wastes

    Energy Technology Data Exchange (ETDEWEB)

    Gulati, S.L.

    1979-09-01

    A nonsynthetic medium was formulated for replacement of mannitol fully by saccharified pea husk (Pisum sativum L.) and water hyacinth (Eichhornia crassipes) with Trichoderma viride QM 9414 and molasses. Yeast extract was partially replaced by proteolysed peak husk, water hyacinth, and mycelium of T. viride QM 9414 by boiling 4 hr with 5% (v/v) HCl. The rhizobial growth was equal in both standard yeast extract mannitol (YEM) and formulated nonsynthetic media. However, barring Rhizobium phaseoli (urid) E-6, the rhizobial counts in the non-synthetic medium were higher than the counts in YEM medium. In the fermentor, rhizobial growth was also almost equal to YEM medium. These results indicated that costly ingredients like mannitol and yeast extract can be replaced by hydrolysates of pea husk, water hyacinth, mycelium of T. viride, and molasses. 5 figures.

  14. Differences between strains of Rhizobium in sensitivity to canavanine

    International Nuclear Information System (INIS)

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

  15. Rhizobium meliloti and Rhizobium leguminosarum dctD gene products bind to tandem sites in an activation sequence located upstream of sigma 54-dependent dctA promoters.

    OpenAIRE

    Ledebur, H; Gu, B.; Sojda, J; Nixon, B T

    1990-01-01

    Free-living rhizobia transport external C4-dicarboxylates to use as sole carbon sources, and uptake of these compounds is essential for nitrogen fixation by rhizobial bacteroids. In both Rhizobium leguminosarum and Rhizobium meliloti, the genes dctB and dctD are believed to form an ntrB/ntrC-like two-component system which regulates the synthesis of a C4-dicarboxylate transport protein encoded by dctA. Here we confirm the identity of sigma 54-dependent promoters previously hypothesized for th...

  16. Endocarditis infecciosa por Rhizobium radiobacter: Reporte de un caso / Infective endocarditis by Rhizobium radiobacter: A case report

    Scientific Electronic Library Online (English)

    Jean Félix, Piñerúa Gonsálvez; Rosanna del Carmen, Zambrano Infantino; Carlos, Calcaño; César, Montaño; Zaida, Fuenmayor; Henry, Rodney; Marianela, Rodney.

    2013-03-01

    Full Text Available Rhizobium radiobacter es una bacteria Gram-negativa, fijadora de nitrógeno que se encuentra principalmente en el suelo. Rara vez causa infecciones en humanos. Ha sido asociada a bacteriemia secundaria a colonización de catéteres intravasculares en pacientes inmunocomprometidos. El objetivo de este t [...] rabajo es informar un caso de endocarditis infecciosa por R. radiobacter. Se trata de paciente masculino, de 47 años de edad, con diagnóstico de enfermedad renal crónica estadio 5 en tratamiento sustitutivo con hemodiálisis, quien acude a centro asistencial por presentar fiebre de dos semanas de evolución. Es hospitalizado, se toman muestras de sangre periférica para hemocultivo y se inicia antibioticoterapia empírica con cefotaxime más vancomicina. El ecocardiograma transtorácico revelo vegetación fusiforme en válvula tricúspide con regurgitación grado III-IV/IV. Al séptimo día del inicio de la antibioterapia el paciente presenta mejoría clínica y paraclínica. La bacteria identificada por hemocultivo es Rhizobium radiobacter resistente a ceftriaxona y sensible a imipenem, amikacina, ampicilina y ampicilina/sulbactam. Debido a la mejoría clínica se decide continuar tratamiento con vancomicina y se anexa imipenem. A los 14 días de iniciada la antibioterapia el paciente es dado de alta con tratamiento ambulatorio con imipenen hasta cumplir seis semanas de tratamiento. En el ecocardiograma control se evidencio ausencia de la vegetación en la válvula tricúspide. Este caso sugiere que R. radiobacter puede ser una causa de endocarditis en pacientes portadores de catéteres intravasculares. Abstract in english Rhizobium radiobacter is a Gram-negative, nitrogen-fixing bacterium, which is found mainly on the ground. It rarely causes infections in humans. It has been associated with bacteremia, secondary to colonization of intravascular catheters, in immunocompromised patients. The aim of this paper was to r [...] eport the case of an infective endocarditis caused by R. radiobacter, in a 47-year-old male, diagnosed with chronic kidney disease stage 5, on replacement therapy with hemodialysis and who attended the medical center with fever of two weeks duration. The patient was hospitalized and samples of peripheral blood were taken for culture. Empirical antibiotic therapy was started with cefotaxime plus vancomycin. The transthoracic echocardiogram revealed fusiform vegetation on the tricuspid valve, with grade III-IV/IV regurgitation. On the seventh day after the start of antibiotic therapy, the patient had a clinical and paraclinical improvement. The bacterium identified by blood culture was Rhizobium radiobacter, ceftriaxone-resistant and sensitive to imipenem, amikacin, ampicillin and ampicillin/ sulbactam. Because of the clinical improvement, it was decided to continue treatment with vancomycin and additionally, with imipenem. At 14 days after the start of antibiotic therapy, the patient was discharged with outpatient treatment with imipenem up to six weeks of treatment. The control echocardiogram showed the absence of vegetation on the tricuspid valve. This case suggests that R. radiobacter can cause endocarditis in patients with intravascular catheters.

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

    Science.gov (United States)

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

    2012-09-01

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

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

    Science.gov (United States)

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

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

    DEFF Research Database (Denmark)

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

    1986-01-01

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

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

    Science.gov (United States)

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

    2015-09-01

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

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

    Science.gov (United States)

    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

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

    Directory of Open Access Journals (Sweden)

    Abdul Khalil Gardezi

    2006-01-01

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

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

    Science.gov (United States)

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

    2012-08-01

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

  4. Stimulation of tetrapyrrole formation in Rhizobium japonicum by restricted aeration.

    Science.gov (United States)

    Avissar, Y J; Nadler, K D

    1978-09-01

    Cultures of Rhizobium japonicum were grown with vigorous aeration to stationary phase and were then incubated under restricted aeration for several days. Under these "microaerobic" conditions, cellular heme content increased 10-fold, and visible amounts of porphyrins were released into the culture medium. The two predominant porphyrins produced were identified, on the basis of their spectrophotometric and chromatographic properties, as protoporphyrin and coproporphyrin. The cytochrome complement of microaerobic cells partially resembled that of the symbiotic bacteria in that cytochromes alpha-alpha3 were absent and a CO-binding cytochrome 552 was present. During the period of restricted aeration, at the time that the heme content was increasing, there was a similar 10-fold increase in the activities of the first two enzymes of heme biosynthesis, delta-aminolevulinic acid synthase and delta-aminolevulinic acid dehydrase. However, during the same period, the activity of succinyl thiokinase (an enzyme that is required in large amounts whether or not heme is being produced) increased only twofold. These results suggest that reduced oxygen tension may play a role in inducing heme synthesis necessary for leghemoglobin formation and bacterial differentiation in soybean root nodules. PMID:690074

  5. Studies on mutation and repair in Rhizobium japonicum

    International Nuclear Information System (INIS)

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

  6. Biologic fixation of nitrogen in irradiated rhizobium strips

    International Nuclear Information System (INIS)

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

  7. Effect of Rhizobium Inoculants on Cowpea under Rainfed Condition

    Directory of Open Access Journals (Sweden)

    Sarker P. C.

    2001-01-01

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

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

    International Nuclear Information System (INIS)

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

  9. [Construction of Frankia genomic libraries and isolation of clones homologous to nodulation genes from Rhizobium leguminosarum].

    Science.gov (United States)

    Cui, Y H; Qin, M; Wang, Y L; Ding, J; Ma, Q S

    1990-01-01

    High molecular genomic DNAs were isolated by using the lysozyme plus achromopeptidase system from Frankia strains At4, Ccol and Hr16, the root nodule endophytes of Alnus, Casuarina and Hippophae respectively, and used to construct genomic libraries in pLAFR1, a broad host range cosmid vector within many gram-negative hosts. The genomic libraries were screened by in situ colony hybridization to identify clones homologous to common nodulation genes of Rhizobium leguminosarum, based on the sequence homology of EcoRI-digested Frankia total DNA to nodABC from Rhizobium meliloti. Several clones showing relatively strong hybridization were found, the recombinant plasmid was isolated, and their homology with Rhizobium nodulation genes was confirmed by spot hybridization. Further work on these positive clones is now underway. PMID:2268450

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

    DEFF Research Database (Denmark)

    Skøt, Leif

    1983-01-01

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

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

    Science.gov (United States)

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

    1993-07-01

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

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

    Science.gov (United States)

    Heath, Katy D.; Lau, Jennifer A.

    2011-03-01

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

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

    Science.gov (United States)

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

    2015-01-01

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

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

    International Nuclear Information System (INIS)

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

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

    Directory of Open Access Journals (Sweden)

    SRI PURWANINGSIH

    2005-04-01

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

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

    OpenAIRE

    Tiercelin, Claudine

    1995-01-01

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

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

    Science.gov (United States)

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

    2012-06-01

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

  18. Étude dans les états finals dileptoniques de différentes propriétés des paires top-antitop avec les détecteurs D0 et ATLAS

    CERN Document Server

    Deterre, Cécile; Déliot, Frédéric

    Les études de différentes propriétés des paires top-antitop dans l’état final dileptonique sont présentées dans cette thèse. Deux analyses ont été réalisées dans des expériences différentes : l’une à D0 auprès du Tevatron, l’autre dans ATLAS auprès du LHC. Les deux collisionneurs étant différents, les mesures qui y sont réalisées sont complémentaires pour les études des propriétés du top.  La première analyse, réalisée dans l’expérience D0, a consisté à faire une mesure simultanée de la section efficace de production des paires top-antitop et du rapport d’embranchement t -> Wb Cette mesure a été réalisée dans le canal dileptonique avec un lot de données correspondant à une luminosité de 5,4 fb?¹. Elle a ensuite été combinée avec la mesure réalisée dans le canal semileptonique pour obtenir une précision de 8% sur la section efficace, comparable à la précision des calculs théoriques. La deuxième analyse présentée, réalisée dans l’expérience A...

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

    International Nuclear Information System (INIS)

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

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

    Science.gov (United States)

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

    2008-07-01

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

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

    Directory of Open Access Journals (Sweden)

    Tehuni Orlando González

    2008-09-01

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

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

    Directory of Open Access Journals (Sweden)

    2009-06-01

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

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

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

    Czech Academy of Sciences Publication Activity Database

    Chovanec, Pavel; Novák, Karel

    2005-01-01

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

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

    Science.gov (United States)

    Appanna, V D

    1989-11-01

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

  5. All nod genes of Rhizobium meliloti are involved in alfalfa nodulation by exo mutants.

    OpenAIRE

    Klein, S.; Walker, G C; Signer, E. R.

    1988-01-01

    Nodulation of alfalfa by exoB mutants of Rhizobium meliloti occurred without root hair curling or infection thread formation. nod exoB double mutants had the same nodulation deficiency as single nod mutants. Therefore, all the known nod genes are involved in nodule induction by exoB mutants, which apparently occurs via intercellular invasion.

  6. Isolation and Selection of Rhizobium Tolerant to Pesticides and Aluminum from Acid Soils in Indonesia

    Directory of Open Access Journals (Sweden)

    Agus Supriyo

    2011-01-01

    Full Text Available Application of Rhizobium as inoculum in acid soil requires specific characters, namely high tolerance to pesticide residues, soil acidity, and high concentration of Aluminum. This study was conducted to isolate Rhizobium having these characters. Inspite of acid soils from Kalimantan, Sumatra, Sulawesi and Java; root nodules of legumes planted in those regions were used as source of isolates. Rhizobial isolation was done using direct isolation and enrichment technique. A paper disc diffusion technique was used in selecting tolerance to pesticides. The selected isolates were examined the tolerance to pH, Al, and ability to form root nodule with soybean. From soil analysis, it could be seen the correlation between pH value and Al concentration. It means that the lower pH value the higher Al concentration. The number of Rhizobium isolates and its tolerance to paraquat was depended on soil type. From 173 strains of isolated Rhizobium, 24 strains were tolerance to pesticides and Aluminum. They were able to grow in wide range of pH, namely 3 – 8, or some of them in 5 - 8. Around 92% of the selected bacteria could form root nodules with soybean plant in different number and size. Hopefully, these isolates can be applied in the pesticide polluted agricultural lands, especially in acid soils with high concentration of Al, and it can also increase soybean production.

  7. Rhizobium freirei sp. nov., a symbiont of Phaseolus vulgaris that is very effective at fixing nitrogen.

    Science.gov (United States)

    Dall'Agnol, Rebeca Fuzinatto; Ribeiro, Renan Augusto; Ormeño-Orrillo, Ernesto; Rogel, Marco Antonio; Delamuta, Jakeline Renata Marçon; Andrade, Diva Souza; Martínez-Romero, Esperanza; Hungria, Mariangela

    2013-11-01

    Common bean (Phaseolus vulgaris L.) can establish symbiotic associations with several Rhizobium species; however, the effectiveness of most strains at fixing nitrogen under field conditions is very low. PRF 81(T) is a very effective strain, usually referred to as Rhizobium tropici and used successfully in thousands of doses of commercial inoculants for the common bean crop in Brazil; it has shown high rates of nitrogen fixation in all areas representative of the crop in the country. Here, we present results that indicate that PRF 81(T), although it belongs to the 'R. tropici group', which includes 10 Rhizobium species, R. tropici, R. leucaenae, R. lusitanum, R. multihospitium, R. miluonense, R. hainanense, R. calliandrae, R. mayense, R. jaguaris and R. rhizogenes, represents a novel species. Several morpho-physiological traits differentiated PRF 81(T) from related species. Differences were also confirmed in the analysis of rep-PCR (sharing less than 45?% similarity with the other species), MLSA with recA, atpD and rpoB genes, and DNA-DNA hybridization. The novel species, for which we propose the name Rhizobium freirei sp. nov., is able to establish effective root nodule symbioses with Phaseolus vulgaris, Leucaena leucocephala, Leucaena esculenta, Crotalaria juncea and Macroptilium atropurpureum. The type strain is PRF 81(T) (?=?CNPSo 122(T)?=?SEMIA 4080(T)?=?IPR-Pv81(T)?=?WDCM 440(T)). PMID:23771622

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

    Science.gov (United States)

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

    2015-08-01

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

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

    Science.gov (United States)

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

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

    OpenAIRE

    1983-01-01

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

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

    Science.gov (United States)

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

    2015-09-01

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

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

    DEFF Research Database (Denmark)

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

    1990-01-01

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

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

    Science.gov (United States)

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

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

    Science.gov (United States)

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

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

    Science.gov (United States)

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

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

    Science.gov (United States)

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

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

    Science.gov (United States)

    Yang, Chu-Fang; Lee, Chi-Mei

    2008-06-01

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

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

    Science.gov (United States)

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

    2011-04-01

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

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

    Science.gov (United States)

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

    2015-12-01

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

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

    Directory of Open Access Journals (Sweden)

    Ladan Bayat

    2014-01-01

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

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

    OpenAIRE

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

    2013-01-01

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

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

    OpenAIRE

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

    1988-01-01

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

  3. Bouvard et Pécuchet et le désir amoureux

    Directory of Open Access Journals (Sweden)

    Anne Herschberg Pierrot

    2010-09-01

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

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

    Science.gov (United States)

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

    1992-07-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2012-07-01

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

  6. Caracterização química dos géis produzidos pelas bactérias diazotróficas Rhizobium tropici e Mesorhizobium sp. / Chemical characterization of the gels produced by the diazotrophic bacteria Rhizobium tropici and Mesorhizobium sp.

    Scientific Electronic Library Online (English)

    Nilson Kobori, Monteiro; Gabriel, Aranda-Selverio; Diego Tadeu Degli, Exposti; Maria de Lourdes Corradi da, Silva; Eliana Gertrudes Macedo, Lemos; João Carlos, Campanharo; Joana Léa Meira, Silveira.

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

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

    Directory of Open Access Journals (Sweden)

    Mihaela Blažinkov

    2007-06-01

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

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

    Science.gov (United States)

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

    1995-10-01

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

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

    International Nuclear Information System (INIS)

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

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

    Directory of Open Access Journals (Sweden)

    M. Aslam

    1999-01-01

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

  11. NolL of Rhizobium sp. Strain NGR234 Is Required for O-Acetyltransferase Activity

    OpenAIRE

    Berck, S.; Perret, X.; Quesada-Vincens, D; Promé, J.-C.; Broughton, W J; Jabbouri, S

    1999-01-01

    Following (iso)flavonoid induction, nodulation genes of the symbiotic nitrogen-fixing bacterium Rhizobium sp. strain NGR234 elaborate a large family of lipooligosaccharidic Nod factors (NodNGR factors). When secreted into the rhizosphere of compatible legumes, these signal molecules initiate root hair deformation and nodule development. The nonreducing glucosamine residue of NodNGR factors are N acylated, N methylated, and mono- or biscarbamoylated, while position C-6 of the reducing extremit...

  12. Scanning Electron Microscopy of Rhizobium trifolii Infection Sites on Root Hairs of White Clover

    OpenAIRE

    Higashi, Shiro; Abe, Mikiko

    1980-01-01

    White clover root hairs which were inoculated with Rhizobium trifolii 4S (infectious strain) contained infection threads which were observed by light microscopy and scanning electron microscopy. Three morphological types of root hairs retaining infection threads were recognized. The bacteria were strongly attached between the surfaces of two plant cell walls as follows: between surfaces of a root hair tip curled back on itself, between a protuberance from a root hair and its cell surface, or ...

  13. Structural studies of alfalfa roots infected with nodulation mutants of Rhizobium meliloti.

    OpenAIRE

    Hirsch, A M; Long, S.R.; Bang, M; Haskins, N; Ausubel, F. M.

    1982-01-01

    Alfalfa roots infected with four nodulation defective (Nod-) mutants of Rhizobium meliloti which were generated by transposon Tn5 mutagenesis were examined by light and electron microscopy. In one class of Nod- mutants, which we can nonreactive, the bacteria did not induce root hair curling or penetrate host cells. In a second class of Nod- mutants, which we call reactive, the bacteria induced some root hair curling and entered root epidermal cells, although no infection threads were formed. ...

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

    OpenAIRE

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

    1990-01-01

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

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

    OpenAIRE

    Robinson, J B; Bauer, W D

    1993-01-01

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

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

    OpenAIRE

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

    1996-01-01

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

  17. Análisis genómico y funcional de los sistemas de Quorum Sensing en Rhizobium leguminosarum

    OpenAIRE

    Sanchez Cañizares, Carmen

    2013-01-01

    Rhizobium leguminosarum (Rl) es una alfa-proteobacteria capaz de establecer una simbiosis diazotrófica con distintas leguminosas. A pesar de la importancia de esta simbiosis en el balance global del ciclo del nitrógeno, muy pocos genomas de rhizobios han sido secuenciados, que aporten nuevos conocimientos relacionados con las características genéticas que contribuyen a importantes procesos simbióticos. Únicamente tres secuencias completas de Rl han sido publicadas: Rl bv. viciae 3841 y dos ge...

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

    OpenAIRE

    Li, De-Ming; Alexander, Martin

    1986-01-01

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

  19. Competition Among Rhizobium spp. for Nodulation of Leucaena leucocephala in Two Tropical Soils †

    OpenAIRE

    Moawad, H.; Bohlool, B. B.

    1984-01-01

    The successful nodulation of legumes by a Rhizobium strain is determined by the competitive ability of that strain against the mixture of other native and inoculant rhizobia. Competition among six Leucaena rhizobial strains in single and multistrain inoculants were studied. Field inoculation trials were conducted in an oxisol and a mollisol soil, both of which contained indigenous Leucaena-nodulating rhizobia. Strain-specific fluorescent antibodies were used for the identification of the stra...

  20. Symbiotic Characteristics and Rhizobium Requirements of a Leucaena leucocephala × Leucaena diversifolia Hybrid and Its Parental Genotypes

    OpenAIRE

    Somasegaran, P.; Martin, R B

    1986-01-01

    In 56-day-old plants, Leucaena leucocephala and its hybrid with L. diversifolia showed 100% more total N than did L. diversifolia. Significant (P < 0.01) host-inoculation interaction in total N was 14.4% of the total phenotypic variation. The most effective and competitive Rhizobium sp. for the leucaenas was TAL 1145. Three-strain mixed inoculation was inferior to TAL 1145 alone.

  1. Osmoregulation in Rhizobium meliloti: Production of Glutamic Acid in Response to Osmotic Stress

    OpenAIRE

    Botsford, James L.; Lewis, Thomas A.

    1990-01-01

    Rhizobium meliloti, like many other bacteria, accumulates high levels of glutamic acid when osmotically stressed. The effect was found to be proportional to the osmolarity of the growth medium. NaCl, KCI, sucrose, and polyethylene glycol elicited this response. The intracellular levels of glutamate and K+ began to increase immediately when cells were shifted to high-osmolarity medium. Antibiotics that inhibit protein synthesis did not affect this increase in glutamate production. Cells growin...

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

    OpenAIRE

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

    1997-01-01

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

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

    OpenAIRE

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

    2011-01-01

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

  4. Rhizobium meliloti lipopolysaccharide and exopolysaccharide can have the same function in the plant-bacterium interaction.

    OpenAIRE

    Putnoky, P; Petrovics, G; Kereszt, A; Grosskopf, E; Ha, D T; Bánfalvi, Z; Kondorosi, A

    1990-01-01

    A fix region of Rhizobium meliloti 41 involved both in symbiotic nodule development and in the adsorption of bacteriophage 16-3 was delimited by directed Tn5 mutagenesis. Mutations in this DNA region were assigned to four complementation units and were mapped close to the pyr-2 and pyr-29 chromosomal markers. Phage inactivation studies with bacterial cell envelope preparations and crude lipopolysaccharides (LPS) as well as preliminary characterization of LPS in the mutants indicated that thes...

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

    OpenAIRE

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

    2008-01-01

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

  6. Interrelations between Meloidogyne javanica, Rotylenchulus reniformis, and Rhizobium Sp. on Vigna sinensis

    OpenAIRE

    Taha, A. H. Y.; Kassab, A.S.

    1980-01-01

    The interactions of Meloidogyne javanica, Rotylenchulus reniformis, and Rhizobium sp. on cowpea seedlings were investigated. Upon simultaneous inoculation with the two nematode species, M. javanica invaded first but did not affect root invasion by R. reniformis. M. javanica populations increased less in competition with R. reniformis than when present alone. Preinvasion by R. renilormis significantly suppressed the number of M. javanica in the roots. Inoculation of M. javanica and/or R. renif...

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

    OpenAIRE

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

    1987-01-01

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

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

    OpenAIRE

    Zahran, Hamdi Hussein

    1999-01-01

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

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

    OpenAIRE

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

    2015-01-01

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

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

    International Nuclear Information System (INIS)

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

  11. Trehalose Biosynthesis in Rhizobium leguminosarum bv. trifolii and Its Role in Desiccation Tolerance?

    OpenAIRE

    McIntyre, Helen J.; Davies, Holiday; Hore, Timothy A; Miller, Simon H.; Dufour, Jean-Pierre; Ronson, Clive W.

    2007-01-01

    Rhizobium leguminosarum bv. trifolii forms nitrogen-fixing root nodules on the pasture legume Trifolium repens, and T. repens seed is often coated with a compatible R. leguminosarum bv. trifolii strain prior to sowing. However, significant losses in bacterial viability occur during the seed-coating process and during storage of the coated seeds, most likely due to desiccation stress. The disaccharide trehalose is known to function as an osmoprotectant, and trehalose accumulation due to de nov...

  12. Introduction of the Escherichia coli gdhA gene into Rhizobium phaseoli: effect on nitrogen fixation.

    OpenAIRE

    Bravo, A.; Becerril, B.; MORA, J.

    1988-01-01

    Rhizobium phaseoli lacks glutamate dehydrogenase (GDH) and assimilates ammonium by the glutamine synthetase-glutamate synthase pathway. A strain of R. phaseoli harboring the Escherichia coli GDH structural gene (gdhA) was constructed. GDH activity was expressed in R. phaseoli in the free-living state and in symbiosis. Nodules with bacteroids that expressed GDH activity had severe impairment of nitrogen fixation. Also, R. phaseoli cells that lost GDH activity and assimilated ammonium by the gl...

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

    OpenAIRE

    Plazinski, Jacek; Barry G. Rolfe

    1985-01-01

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

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

    OpenAIRE

    Alfano, J R; Kahn, M. L.

    1993-01-01

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

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

    OpenAIRE

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

    1985-01-01

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

  16. Nodulation and Nitrogen Fixation Efficacy of Rhizobium fredii with Phaseolus vulgaris Genotypes

    OpenAIRE

    Sadowsky, Michael J.; Cregan, Perry B.; Keyser, Harold H.

    1988-01-01

    Phaseolus plant introduction (PI) genotypes (consisting of 684 P. vulgaris, 26 P. acutifolius, 39 P. lunatus, and 5 P. coccineus accessions) were evaluated for their ability to form effective symbioses with strains of six slow-growing (Bradyrhizobium) and four fast-growing (Rhizobium fredii) soybean rhizobia. Of the 684 P. vulgaris genotypes examined, three PIs were found to form effective nitrogen-fixing symbioses with the R. fredii strains. While none of the Bradyrhizobium strains nodulated...

  17. Rhizobium sp. Degradation of Legume Root Hair Cell Wall at the Site of Infection Thread Origin

    OpenAIRE

    Ridge, Robert W.; Barry G. Rolfe

    1985-01-01

    Using a new microinoculation technique, we demonstrated that penetration of Rhizobium sp. into the host root hair cell occurs at 20 to 22 h after inoculation. It did this by dissolving the cell wall maxtrix, leaving a layer of depolymerized wall microfibrils. Colony growth pressure “stretched” the weakened wall, forming a bulge into an interfacial zone between the wall and plasmalemma. At the same time vesicular bodies, similar to plasmalemmasomes, accumulated at the penetration site in a man...

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

    Directory of Open Access Journals (Sweden)

    Vasilica STAN

    2011-05-01

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

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

    Directory of Open Access Journals (Sweden)

    A. Arfaoui

    2005-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Joši? Dragana

    2008-01-01

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

  1. Cloning and DNA Sequence Analysis of the Haloalkanoic Permease Uptake Gene from Rhizobium sp. RC1

    Directory of Open Access Journals (Sweden)

    S. Hamdan

    2010-01-01

    Full Text Available The aims of the study were to clone and identify the putative haloacid permease gene in Rhizobium sp. RC1. The putative dehrP gene encoding an uptake protein in Rhizobium sp. RC1 was identified by DNA sequence analysis. An approximately 3.8 kb DNA sequence upstream of dehalogenase D (dehD in plasmid pSC1 was analyzed and revealed an open reading frame of 1239 kb which encoded for 412 amino acids with calculated subunit molecular weight of 45 kDa and isoelectric point of 9.78. The amino acid sequence of DehrP gave high sequence identity of 86% with putative monochloropropionic acid permease from Agrobacterium sp. NHG3 and 62% with haloacid-specific transporter from Burkholderia cepacia MBA4. Comparison of the predicted amino acid sequence with the CD server (www.ncbi.nlm.nih.gov NCBI database also revealed the putative DehrP contained signatures of sugar transport proteins of an integral membrane protein. Therefore, a new Rhizobial dehalogenase genetic organization was proposed. However, further characterization of this transporter protein is required to fully comprehend the dehalogenase uptake system of Rhizobium sp. RC1.

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

    Directory of Open Access Journals (Sweden)

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

    2012-05-01

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

  3. Une fosse du Bronze final IIb dans le Val d’Orléans à Sandillon (Loiret : données archéologiques et contexte environnemental A Late Bronze Age pit IIb in the Val d’Orléans at Sandillon (Loiret: archaeological data and environmental context

    Directory of Open Access Journals (Sweden)

    Hélène Froquet

    2008-06-01

    Full Text Available Un diagnostic archéologique réalisé en 2004 à Sandillon (Loiret a permis la découverte d’une occupation du Bronze final IIb dans la plaine alluviale de la Loire. Les structures sont peu nombreuses, mais une fosse se distingue par un ensemble céramique exceptionnel par sa richesse, sa conservation et la présence de formes encore inconnues en région Centre. Ce corpus céramique, corrélé par une datation par radiocarbone, offre désormais un jalon fiable pour la région. Par ailleurs, ces vestiges ont pu être replacés dans leur environnement immédiat grâce à une étude géomorphologique et à l’analyse des restes carpologiques contenus dans la fosse. Ainsi, le croisement des données permet de tenter une approche paléo environnementale sur une occupation en contexte fluviatile et de préciser les relations entre l’homme et son milieu durant cette période chronologique.An archaeological diagnostic carried out in 2004 at Sandillon (Loiret enabled the discovery of a final Bronze Age IIb occupation in the alluvial Loire valley. There are few structures but one pit is noteworthy for a ceramic collection, exceptional in its abundance, its preservation and the presence of previously unknown forms in the Centre region. This ceramic corpus, dated by radiocarbon, henceforth provides a reliable standard for the region. Moreover, these relics could be set in their immediate environment thanks to a geomorphological study and to the analysis of carpological remains contained in the pit. So, the crossing of data allows us to attempt an environmental paleolithic approach to an occupation in a freshwater context and to clarify the relationship between man and his environment in this chronological period.

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

    International Nuclear Information System (INIS)

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

  5. Evaluation of bean (Phaseolus vulgaris) seeds inoculation with Rhizobium phaseoli and plant growth promoting rhizobacteria on yield and yield components.

    Science.gov (United States)

    Yadegari, M; Rahmani, H A; Noormohammadi, G; Ayneband, A

    2008-08-01

    To study the effect of co-inoculation with plant growth-promoting rhizobacteria (PGPR) and Rhizobium, on yield and yield components of common bean (Phaseolus vulgaris L.) cultivars was investigated in 2 consecutive years under field condition of plant growing evidence indicates that soil beneficial bacteria can positively affect symbiotic performance of rhizobia. PGPR strains Pseudomonas fluorescens P-93 and Azospirillum lipoferum S-21 as well as two highly effective Rhizobium strains were used in this study. Common bean seeds of three cultivars were inoculated with Rhizobium singly or in a combination with PGPR to evaluate their effect on growth characters. A significant variation of plant growth in response to inoculation with Rhizobium strains was observed. Treatment with PGPR significantly increased pod per plant, number of seeds per pod, weight of 100 seed, weight of seeds per plant, weight of pods per plant, total dry matter in R6 as well as seed yield and protein content. Co-inoculation with Rhizobium and PGPR demonstrated a significant increase in the yield and yield components. The results showed that all treatments of bacteria increased yield; however, strains Rb-133 with Pseudomonas fluorescens P-93 gave the highest seed yield, number of pods per plant, weight of 100 seed, seed protein yield, number seed per pod, seed protein yield. PMID:18983036

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

    Directory of Open Access Journals (Sweden)

    M. Yadegari

    2008-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Askary Mehry

    2008-01-01

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

  8. 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)

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

    Energy Technology Data Exchange (ETDEWEB)

    Lamy, C.

    2005-07-01

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

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

    Directory of Open Access Journals (Sweden)

    Isnia Aparecida de Oliveira

    2000-03-01

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

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

    Directory of Open Access Journals (Sweden)

    Brom Susana

    2011-06-01

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

  12. Symbiotic effectiveness and ecological characterization of indigenous Rhizobium loti populations in Uruguay Eficiência simbiótica e caracterização ecológica de uma população nativa de Rhizobium loti no Uruguai

    Directory of Open Access Journals (Sweden)

    Amalia Baraibar

    1999-06-01

    Full Text Available The objectives of this work were to describe the distribution, density and seasonal variation of the indigenous populations of Rhizobium loti in different Uruguayan soils and to determine the symbiotic effectiveness and stress tolerance factors of different isolates, both with the aim of obtaining selected strains to re-introduce as inoculants in Lotus pastures. R. loti was present in ten soils studied and their densities varied from year to year and within each soil. All the isolates nodulated Lotus corniculatus effectively. The nodules in Lotus pedunculatus and Lotus subbiflorus were small, red on the surface and ineffective in nitrogen fixation. The study of 50 isolates from the ten soils showed high variability in their symbiotic efficiency and tolerance to pH. The indigenous population was acid tolerant in culture medium (pH 4.5, 83% of them could grow at pH 4.5 in 3 days. This work showed that there was a great diversity between the strains of R. loti isolated from Uruguayan soils and supports the importance of selecting among them the most efficient and resistant strains to be included in the inoculants.Os objetivos deste trabalho foram descrever a distribuição, densidade e variação sazonal de populações nativas de Rhizobium loti em diferentes solos uruguaios, e determinar a eficiência simbiótica e os fatores de tolerância a estresse de diversos isolados, tendo em vista a obtenção de cepas a serem reintroduzidas como inoculantes em pastagens de Lotus. Rhizobium loti estava presente em dez solos estudados, e suas densidades variavam de ano para ano e em cada solo. Todos os isolados nodularam efetivamente o Lotus corniculatus. Os nódulos no Lotus pedunculatus e no Lotus subbiflorus eram pequenos, vermelhos na superfície, e ineficazes na fixação de N. O estudo de 50 isolados dos dez solos mostraram alta variabilidade na sua eficiência simbiótica, e alta tolerância ao pH. A população nativa era tolerante à acidez em meio de cultura (pH 4,5; 83% dela pode crescer em pH 4,5 em três dias. O presente trabalho mostrou que há grande diversidade entre as cepas de R. loti isoladas de solos uruguaios, e acentua a importância de se selecionar entre elas as mais eficientes e resistentes, para serem incluídas como inoculantes.

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

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

  15. Mythe et pouvoir

    Directory of Open Access Journals (Sweden)

    Alejandro Ruidrejo

    2013-07-01

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

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

    International Nuclear Information System (INIS)

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

  17. Identification and Characterization of the Rhizobium sp. Strain GIN611 Glycoside Oxidoreductase Resulting in the Deglycosylation of Ginsenosides

    OpenAIRE

    Kim, Eun-Mi; Kim, Juhan; Seo, Joo-Hyun; Park, Jun-Seong; Kim, Duck-Hee; Kim, Byung-Gee

    2012-01-01

    Using enrichment culture, Rhizobium sp. strain GIN611 was isolated as having activity for deglycosylation of a ginsenoside, compound K (CK). The purified heterodimeric protein complex from Rhizobium sp. GIN611 consisted of two subunits with molecular masses of 63.5 kDa and 17.5 kDa. In the genome, the coding sequence for the small subunit was located right after the sequence for the large subunit, with one nucleotide overlapping. The large subunit showed CK oxidation activity, and the deglyco...

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

    OpenAIRE

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

    1989-01-01

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

  19. Associação de Rhizobium sp. a duas leguminosas na tolerância à atrazina / Association of Rhizobium sp. with two legumes on atrazine tolerance

    Scientific Electronic Library Online (English)

    Danielle, Camargo; Kelly Lopes, Bispo; Luciane, Sene.

    2011-08-01

    Full Text Available A associação de bactérias a plantas tem sido estudada como uma possível tecnologia emergente, para fitorremediação de contaminantes, entre eles os herbicidas, que, por sua recalcitrância, ameaçam a qualidade do ambiente. O objetivo deste trabalho foi verificar a tolerância de mucuna-anã (Stizolobium [...] deeringianum Bort) e mucuna-preta (Stizolobium aterrimum Piper & Tracy), inoculadas e não inoculadas com Rhizobium sp., ao herbicida atrazina. Os tratamentos foram: plantas com inoculante + 0,1 g/m², 0,2 g/m² atrazina e sem atrazina (T1, T2 e T3, respectivamente), sem inoculante + 0,1 g/m², 0,2 g/m² atrazina e sem atrazina (T4, T5 e T6, respectivamente). O delineamento experimental utilizado foi inteiramente casualizado, com três repetições. Foram avaliados germinação, sobrevivência, número de nódulos, altura, biomassa verde, biomassa seca da parte aérea, após o crescimento das plantas por 50 dias em casa de vegetação. Nos tratamentos com inoculante, avaliou-se a porcentagem de germinação de plantas bioindicadoras (Bidens pilosa L.). Mucuna-preta e mucuna-anã demonstraram maior tolerância ao herbicida quando associadas ao Rhizobium. Os valores de sobrevivência de mucuna-preta, nas doses 0,1 e 0,2 g/m² de atrazina (T1 e T2), foram de 34 a 24% superiores aos observados nas mesmas doses, mas sem o inoculante (T4 e T5). Para mucuna-anã, T1 e T2 foram de 17 e 8% superiores a T4 e T5, respectivamente. As alturas médias de mucuna-anã em T1, T2 e T3 foram mais elevadas que em T4, T5 e T6, reforçando a importância do simbionte à resistência ao herbicida. Os resultados encontrados para as variáveis altura, biomassa verde e seca para mucuna-preta não apresentaram diferença estatística entre os tratamentos com e sem inoculante, mostrando uma resistência natural à atrazina e a possibilidade de atuar como planta remediadora. A germinação de B. pilosa indica uma possível degradação da atrazina no solo com ambas as espécies de mucunas inoculadas com Rhizobium sp. Abstract in english The association of bacteria with plants has been studied as a possible emerging technology for phytoremediation of contaminants, including herbicides, which pose as a threatening to environmental quality due to their recalcitrance. The aim of this study was to assess the tolerance of dwarf mucuna (S [...] tizolobium deeringianum Bort) and black mucuna (Stizolobium aterrimum Piper & Tracy) inoculated and uninoculated with Rhizobium to the herbicide atrazine. The treatments were: plants with inoculant + 0.1 g/m², 0.2 g/m² atrazine, and without atrazine (T1, T2 and T3, respectively), plants without inoculant + 0.1 g/m², 0.2 g/m² atrazine and without atrazine (T4, T5 and T6, respectively). The experiment was arranged in a completely randomized design, with three replications. Plants were grown in a greenhouse for 50 days and the variables germination, survival, number of nodules, height, green/dry biomass of the aerial part were evaluated. In the treatments with inoculants, the germination percentage of bioindicator plants (Bidens pilosa L.) was also evaluated. Black mucuna and dwarf mucuna showed greater tolerance to the herbicide when associated with Rhizobium. The survival rates of black mucuna at the doses 0.1 and 0.2 g/m² atrazine (T1 and T2) were 34 and 24% higher than those observed at the same doses, but without the inoculant (T4 and T5). For dwarf mucuna, T1 and T2 were 17 and 8% higher than T4 and T5, respectively. The average heights of dwarf mucuna in T1, T2 and T3 were higher than in T4, T5 and T6, reinforcing the importance of the symbiont to the herbicide resistance. The results found for the variables height, green and dry biomass for black mucuna were not significantly different among the treatments with and without inoculant, showing a natural resistance to atrazine and the possibility of acting as a remediation plant. The germination of B. pilosa indicates a possible degradation of atrazine in the soil by both mucuna species inoculated with Rhizobium sp.

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

    OpenAIRE

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

    1989-01-01

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

  1. Identification and mobilization by cointegrate formation of a nodulation plasmid in Rhizobium trifolii.

    OpenAIRE

    Scott, D. B.; Ronson, C W

    1982-01-01

    A nodulation plasmid, pRtr-514a, of molecular size 180 megadaltons (Mdal) was identified in Rhizobium trifolii strain NZP514. This plasmid was absent in both spontaneous and heat-cured Nod- derivatives of NZP514, and these strains were unable to induce root hair curling. The ability to nodulate clover was transferred from the wild-type strain to a Nod- derivatives, PN104, with the broad-host-range plasmid R68.45 (39 megadaltons) at a cotransfer frequency of about 4 X 10(-3). Most of the Nod+ ...

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

    OpenAIRE

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

    1992-01-01

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

  3. Alteration of surface properties in a Tn5 mutant strain of Rhizobium trifolii 0403.

    OpenAIRE

    Gardiol, A E; Hollingsworth, R. I.; Dazzo, F. B.

    1987-01-01

    A symbiotically defective mutant strain of Rhizobium trifolii, UR251, was obtained by transposon Tn5 mutagenesis of R. trifolii 0403 rif and recognized by its partially ineffective (Fix +/-) phenotype on white clover plants. UR251 had a single Tn5 insertion in plasmid DNA, a wild-type plasmid pattern, and no detectable Mu DNA sequences originally present in the vector used for Tn5 mutagenesis. Agglutination by the clover lectin trifoliin A and attachment to clover root hairs was higher with U...

  4. Correlation between extracellular fibrils and attachment of Rhizobium leguminosarum to pea root hair tips.

    OpenAIRE

    Smit, G.; Kijne, J.W.; Lugtenberg, B J

    1986-01-01

    As part of a project meant to characterize molecules involved in nodulation, a semiquantitative microscopic assay was developed for measuring attachment of Rhizobium leguminosarum cells to pea root hair tips, i.e., the site at which R. leguminosarum initiates nodulation. This form of attachment, designated as cap formation, was dependent on the incubation pH and growth phase, with optimal attachment at pH 7.5 and with bacteria in the early stationary phase of growth. Addition of glucose to th...

  5. Sym plasmid transfer to various symbiotic mutants of Rhizobium trifolii, R. leguminosarum, and R. meliloti.

    OpenAIRE

    Djordjevic, M.A.; Zurkowski, W; Shine, J; Rolfe, B.G.

    1983-01-01

    Two self-transmissible Sym(biosis) plasmids, one encoding pea-specific nodulation and nitrogen-fixation functions (plasmid pJB5JI) and the other encoding clover-specific nodulation and nitrogen-fixation functions (plasmid pBR1AN) were used to determine whether the symbiotic genes encoded on these plasmids are expressed in various members of the Rhizobiaceae. The host specificity of Rhizobium trifolii and R. leguminosarum Sym plasmid-cured strains could be directly determined by the transfer t...

  6. Positive and negative control of nod gene expression in Rhizobium meliloti is required for optimal nodulation

    OpenAIRE

    Kondorosi, Eva; Gyuris, Jenö; Schmidt, Jürgen; John, Michael; Duda, Ernö; Hoffmann, Beate; Schell, Jeff; Kondorosi, Adam

    1989-01-01

    We show that expression of common nodulation genes in Rhizobium meliloti is under positive as well as negative control. A repressor protein was found to be involved in the negative control of nod gene expression. Whereas the activator NodD protein binds to the conserved cis-regulatory element (nod-box) required for coordinated regulation of nod genes, the repressor binds to the overlapping nodD1 and nodA promoters, at the RNA polymerase binding site. A model depicting the possible interaction...

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

    OpenAIRE

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

    1993-01-01

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

  8. Molecular cloning and genetic organization of C4-dicarboxylate transport genes from Rhizobium leguminosarum.

    OpenAIRE

    Ronson, C W; Astwood, P M; Downie, J. A.

    1984-01-01

    Cosmids containing C4-dicarboxylate transport (dct) genes were identified from a gene bank of Rhizobium leguminosarum DNA made in the broad-host-range vector pLAFR1 by their ability to complement R. trifolii dct mutants. The dct genes were further characterized by subcloning, restriction site mapping, and transposon Tn5 and Tn7 mutageneses. Three dct loci were identified within a 5.5-kilobase region of DNA, in the order dctA-dctB-dctC. The results suggested that dctA encoded a structural comp...

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

    Directory of Open Access Journals (Sweden)

    Balaji Hajare and Avinash Ade1

    2012-06-01

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

  10. Arbuscular mycorrhizal fungi and rhizobium facilitate nitrogen uptake and transfer in soybean/maize intercropping system

    Science.gov (United States)

    Meng, Lingbo; Zhang, Aiyuan; Wang, Fei; Han, Xiaoguang; Wang, Dejiang; Li, Shumin

    2015-01-01

    The tripartite symbiosis between legumes, rhizobia and mycorrhizal fungi are generally considered to be beneficial for the nitrogen (N) uptake of legumes, but the facilitation of symbiosis in legume/non-legume intercropping systems is not clear. Therefore, the aims of the research are as follows: (1) to verify if the dual inoculation can facilitate the N uptake and N transfer in maize/soybean intercropping systems and (2) to calculate how much N will be transferred from soybean to maize. A pot experiment with different root separations [solid barrier, mesh (30 ?m) barrier and no barrier] was conducted, and the 15N isotopic tracing method was used to calculate how much N transferred from soybean to maize inoculated with arbuscular mycorrhizal fungi (AMF) and rhizobium in a soybean (Glycine max L.cv. Dongnong No. 42)/maize (Zea mays L.cv. Dongnong No. 48) intercropping system. Compared with the Glomus mosseae inoculation (G.m.), Rhizobium SH212 inoculation (SH212), no inoculation (NI), the dual inoculation (SH212+G.m.) increased the N uptake of soybean by 28.69, 39.58, and 93.07% in a solid barrier system. N uptake of maize inoculated with both G. mosseae and rhizobium was 1.20, 1.28, and 1.68 times more than that of G.m., SH212 and NI, respectively, in solid barrier treatments. In addition, the amount of N transferred from soybean to maize in a dual inoculation system with a mesh barrier was 7.25, 7.01, and 11.45 mg more than that of G.m., SH212 and NI and similarly, 6.40, 7.58, and 12.46 mg increased in no barrier treatments. Inoculating with both AMF and rhizobium in the soybean/maize intercropping system improved the N fixation efficiency of soybean and promoted N transfer from soybean to maize, resulting in the improvement of yield advantages of legume/non-legume intercropping. PMID:26029236

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

    OpenAIRE

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

    1983-01-01

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

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

    OpenAIRE

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

    1982-01-01

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

  13. Genome sequence of the clover-nodulating Rhizobium leguminosarum bv. trifolii strain SRDI565.

    OpenAIRE

    Reeve, Wayne; Drew, Elizabeth; Ballard, Ross; Melino, Vanessa; Rui TIAN; De Meyer, Sofie; Brau, Lambert; Ninawi, Mohamed; Teshima, Hazuki; Goodwin, Lynne; Chain, Patrick; Liolios, Konstantinos; Pati, Amrita; Mavromatis, Konstantinos; Ivanova, Natalia

    2013-01-01

    Rhizobium leguminosarum bv. trifolii SRDI565 (syn. N8-J) is an aerobic, motile, Gram-negative, non-spore-forming rod. SRDI565 was isolated from a nodule recovered from the roots of the annual clover Trifolium subterraneum subsp. subterraneum grown in the greenhouse and inoculated with soil collected from New South Wales, Australia. SRDI565 has a broad host range for nodulation within the clover genus, however N2-fixation is sub-optimal with some Trifolium species and ineffective with others. ...

  14. Genome sequence of the clover-nodulating Rhizobium leguminosarum bv. trifolii strain SRDI943.

    OpenAIRE

    Reeve, Wayne; Drew, Elizabeth; Ballard, Ross; Melino, Vanessa; Rui TIAN; De Meyer, Sofie; Brau, Lambert; Ninawi, Mohamed; Daligault, Hajnalka; Davenport, Karen; Erkkila, Tracy; Goodwin, Lynne; Gu, Wei; Munk, Christine; Teshima, Hazuki

    2013-01-01

    Rhizobium leguminosarum bv. trifolii SRDI943 (strain syn. V2-2) is an aerobic, motile, Gram-negative, non-spore-forming rod that was isolated from a root nodule of Trifolium michelianum Savi cv. Paradana that had been grown in soil collected from a mixed pasture in Victoria, Australia. This isolate was found to have a broad clover host range but was sub-optimal for nitrogen fixation with T. subterraneum (fixing 20-54% of reference inoculant strain WSM1325) and was found to be totally ineffect...

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

    International Nuclear Information System (INIS)

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

  16. Rhizobium japonicum mutants that are hypersensitive to repression of H2 uptake by oxygen.

    OpenAIRE

    Maier, R J; Merberg, D M

    1982-01-01

    The synthesis of an H2 oxidation system in free-living Rhizobium japonicum wild-type strain SR is repressed by oxygen. Maximal H2 uptake rates were obtained in strain SR after derepression in 11 microM or less dissolved oxygen. Oxygen levels above 45 microM completely repressed H2 uptake in strain SR. Five R. japonicum mutant strains that are hypersensitive to repression or H2 oxidation by oxygen were derived from strain SR. The mutants were obtained by screening H2 uptake-negative mutants th...

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

    OpenAIRE

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

    1996-01-01

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

  18. Acetyl Coenzyme A Acetyltransferase of Rhizobium sp. (Cicer) Strain CC 1192

    OpenAIRE

    Kim, S A; Copeland, L.

    1997-01-01

    To investigate why Rhizobium sp. (Cicer) strain CC 1192 cells accumulate poly-R-3-hydroxybutyrate in the free-living state but not as bacteroids in nodules on chickpea (Cicer arietinum L.) plants, we have examined the kinetic properties of acetyl coenzyme A (acetyl-CoA) acetyltransferase (also known as acetoacetyl-CoA thiolase and 3-ketothiolase [EC 2.3.1.9]) from both types of cells. The enzyme had a native molecular mass of 180 (plusmn) 4 kDa, and the subunit molecular mass was 44 (plusmn) ...

  19. Accumulation of alpha,alpha-trehalose by Rhizobium bacteria and bacteroids.

    OpenAIRE

    Streeter, J. G.

    1985-01-01

    Four strains of Rhizobium japonicum (61A76 and USDA 110, 123, and 138) were grown in eight different defined media. Regardless of the carbon or nitrogen source supplied, alpha, alpha-trehalose was the major carbohydrate (among mono- and disaccharides) accumulated by all four strains. After 7 to 9 days of growth, trehalose generally accounted for 90 to 100% of the mono- and disaccharides detected. None of the four strains would grow with trehalose as a carbon source, but the utilization of end...

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

    Science.gov (United States)

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

    1995-07-01

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

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

    International Nuclear Information System (INIS)

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

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

    OpenAIRE

    Better, M; Helinski, D. R.

    1983-01-01

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

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

    OpenAIRE

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

    1980-01-01

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

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

    OpenAIRE

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

    1995-01-01

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

  5. Caracterização química dos géis produzidos pelas bactérias diazotróficas Rhizobium tropici e Mesorhizobium sp.

    Directory of Open Access Journals (Sweden)

    Nilson Kobori Monteiro

    2012-01-01

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

  6. Dodecaprenyl Phosphate-Galacturonic Acid as a Donor Substrate for Lipopolysaccharide Core Glycosylation in Rhizobium leguminosarum*

    OpenAIRE

    Kanjilal-Kolar, Suparna; Raetz, Christian R H

    2006-01-01

    The lipid A and inner core regions of Rhizobium leguminosarum lipopolysaccharide contain four galacturonic acid (GalA) residues. Two are attached to the outer unit of the 3-deoxy-D-manno-octulosonic acid (Kdo) disaccharide, one to the mannose residue, and one to the 4?-position of lipid A. The enzymes RgtA and RgtB, described in the accompanying article, catalyze GalA transfer to the Kdo residue, whereas RgtC is responsible for modification of the core mannose unit. Heterologous expression of...

  7. Evolución del tamaño y del peso del fruto de kiwi (Actinidia deliciosa (A. Chev.) Liang et Fergurson) cultivar "Hayward" durante la etapa final de crecimiento / Evolution of the size and weight of "Hayward" kiwifruit (Actinidia deliciosa (A. Chev.) Liang et Fergurson) cultivar during the final stage of growth

    Scientific Electronic Library Online (English)

    Mónica G, Ontivero Urquiza; Héctor Abel, Altube; Leonardo, Baghin.

    2012-12-01

    Full Text Available Se realizó un ensayo durante tres años consecutivos con el fin de monitorear la evolución del tamaño y del peso de los frutos de una plantación comercial de kiwi variedad Hayward ubicada en la provincia de Córdoba. El objetivo fue determinar la evolución del peso y del tamaño del fruto durante la et [...] apa final de crecimiento. Se seleccionaron doce plantas representativas y se realizaron cosechas durante cuatro semanas en tres años sucesivos desde el 4/3 al 24/3, a partir de que los frutos alcanzaron 5° Brix. Las variables evaluadas fueron: peso del fruto, longitud del fruto, diámetro mayor y menor al momento de la cosecha y luego de seis días a temperatura ambiente. El peso del fruto se incrementó desde un valor mínimo de 83,71 g a 121,1 g. La pérdida de peso luego de seis días fue desde un mínimo de 3,11 g a un máximo de 6,01 g. La longitud pasó de 54,73 mm a 64,20 mm. El diámetro mayor pasó de 52,12 mm a 59,7 mm, presentando una disminución después de seis días de un mínimo de 0,27 mm a un máximo 7,12 mm. El diámetro menor pasó de 42 mm a 54,41 mm entre la primera y la cuarta cosecha. Todas las variables presentaron un incremento en la medida en que atrasaba la cosecha, lo que justifica una cosecha más tardía, en función del tamaño de los frutos. Abstract in english A follow-up trial of the evolution of fruit size and fruit weight of a "Hayward" kiwifruit cultivar was conducted in a commercial plantation in the province of Córdoba during three consecutive years. Twelve representative plants were selected and kiwifruit were harvested during three consecutive yea [...] rs, during four weeks, from March 4th to March 24th, when they reached 5° Brix. The examined variables were fruit weight, fruit length, major diameter and minor diameter of the fruit at the moment of harvest and after six days at room temperature. Fruit weight increased from a minimum value of 83.71 g to 121.1 g. After six days, the weight loss varied from a minimum of 3.11 g to a maximum of 6.01 g. Fruit length went from 54.73 mm to 64.20 mm. The major diameter varied from 52.12 mm to 59.7 mm presenting a decrease after six days from a minimum of 0.27 mm to a maximum of 7.12 mm. The minor diameter went from 42 mm to 54.41 mm between the first and the fourth harvest. All the variables showed an increase as the harvest was delayed, which seems to justify a later harvest considering the size of the fruit.

  8. The acetyl substituent of succinoglycan is not necessary for alfalfa nodule invasion by Rhizobium meliloti Rm1021.

    OpenAIRE

    Reuber, T L; Walker, G C

    1993-01-01

    Rhizobium meliloti Rm1021 requires a Calcofluor-binding exopolysaccharide, termed succinoglycan or EPS I, to invade alfalfa nodules. We have determined that a strain carrying a mutation in the exoZ locus produces succinoglycan that lacks the acetyl substituent. The exoZ mutant nodules alfalfa normally.

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

    Science.gov (United States)

    Suwa, Tomomi; Williamson, Brad

    2014-01-01

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

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

    Science.gov (United States)

    Suwa, Tomomi; Williamson, Brad

    2014-01-01

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

  11. The structure and molecular mechanics calculations of the cyclic (1 ? 2)-?- D-glucan secreted by Rhizobium tropici CIAT 899

    Science.gov (United States)

    Gil Serrano, Antonio M.; Franco-Rodríguez, Guillermo; González-Jiménez, Isabel; Tejero-Mateo, Pilar; Molina, José Molina; Dobado, J. A.; Megías, Manuel; Romero, Maria Jesús

    1993-12-01

    The structure of the extracellular cyclic (1 ? 2)-?- D-glucan secreted by Rhizobium tropici CIAT 899 has been studied by methylation analysis, 1D and 2D NMR experiments, HPLC and FAB-MS. Molecular mechanics (MM2) and theoretical 3JHH coupling constants calculations were performed.

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

    International Nuclear Information System (INIS)

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

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

    Science.gov (United States)

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

    1996-07-01

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

  14. 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

  15. Studies on Nodulation, Biochemical Analysis and Protein Profiles of Rhizobium Isolated From Indigofera species

    Directory of Open Access Journals (Sweden)

    Kumari, B. S.

    2010-01-01

    Full Text Available Nodulation characteristics in five species of Indigofera viz., I .trita, I. linnaei, I. astragalina, I. parviflora and I. viscosa was studied at regular intervals on the plants raised in garden soil. Among the species studied, highest average number of nodules per plant of 23 with maximum sized nodules of 8.0 mm diameter was observed in I. astragalina. Biochemical analysis of root nodules of I. astragalina revealed that the leghaemoglobin content of nodules and nitrogen content of root, shoot, leaves and nodules were gradually increased up to 60 DAS, and then decreased with increase in age. Rhizobium isolates of five species of Indigofera were isolated and screened for enzymatic activities and total cellular protein profiles. All the five isolates showed nitrate reductase, citrase, tryptophanase and catalase activity while much variation was observed for enzymes like gelatinase, urease, caseinase, lipase, amylase, lysine decarboxylase and protease activities. Among the isolates studied, only the isolate from I. viscosa has the ability to solubilize the insoluble tricalcium phosphate. All the Rhizobium isolates exhibit similarity in protein content, except the isolate from I. viscosa which showed one additional protein band.

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

    Science.gov (United States)

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

    2015-01-01

    The objective of this study was to evaluate the exopolysaccharide (EPS) production by Rhizobium leguminosarum cultivated in wastewater generated by oil companies (WWOC1 and WWOC2) and fish processing industry (WWFP). The results obtained in Erlenmeyer flasks indicated that the rhizobial strain grew well in industrial wastewater. Generally, wastewater composition affected the growth and the EPS production. WWFP allowed good bacterial growth similar to that obtained with the standard medium (YMB). During growth, various quantities of EPS were produced and yields varied depending on the media. Growing in YMB, EPS production did not exceed 9.7 g/L obtained after 72 h of growth. In wastewater, the maximum EPS value reached 11.1 g/L obtained with the fish processing wastewater, after 72 h of growth. The use of a mixture of the oil company wastewater (WWOC2) and the fish processing wastewater (WWFP) as culture medium affected not only the rhizobial strain growth, but also EPS production. The highest EPS (42.4 g/L, after 96 h of culture) was obtained using a ratio of WWFP and WWOC2 of 50:50 (v:v). Therefore, this work shows the ability of Rhizobium leguminosarum, growing in industrial wastewater as new economic medium, to produce EPS. This biopolymer could be applied in enormous biotechnological areas. PMID:26273255

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

    Directory of Open Access Journals (Sweden)

    Raposeiras Rui

    2002-01-01

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

  18. 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

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

    Science.gov (United States)

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

    2015-01-01

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

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

    Science.gov (United States)

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

    2006-03-01

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

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

    Scientific Electronic Library Online (English)

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

    2015-06-01

    Full Text Available The objective of this study was to evaluate the exopolysaccharide (EPS) production by Rhizobium leguminosarum cultivated in wastewater generated by oil companies (WWOC1 and WWOC2) and fish processing industry (WWFP). The results obtained in Erlenmeyer flasks indicated that the rhizobial strain grew [...] well in industrial wastewater. Generally, wastewater composition affected the growth and the EPS production. WWFP allowed good bacterial growth similar to that obtained with the standard medium (YMB). During growth, various quantities of EPS were produced and yields varied depending on the media. Growing in YMB, EPS production did not exceed 9.7 g/L obtained after 72 h of growth. In wastewater, the maximum EPS value reached 11.1 g/L obtained with the fish processing wastewater, after 72 h of growth. The use of a mixture of the oil company wastewater (WWOC2) and the fish processing wastewater (WWFP) as culture medium affected not only the rhizobial strain growth, but also EPS production. The highest EPS (42.4 g/L, after 96 h of culture) was obtained using a ratio of WWFP and WWOC2 of 50:50 (v:v). Therefore, this work shows the ability of Rhizobium leguminosarum, growing in industrial wastewater as new economic medium, to produce EPS. This biopolymer could be applied in enormous biotechnological areas.

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

    Science.gov (United States)

    Kingsley, M T; Bohlool, B B

    1981-08-01

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

  3. Role of Rhizobium endoglucanase CelC2 in cellulose biosynthesis and biofilm formation on plant roots and abiotic surfaces

    Directory of Open Access Journals (Sweden)

    Robledo M

    2012-09-01

    Full Text Available Abstract Background The synthesis of cellulose is among the most important but poorly understood biochemical processes, especially in bacteria, due to its complexity and high degree of regulation. In this study, we analyzed both the production of cellulose by all known members of the Rhizobiaceae and the diversity of Rhizobium celABC operon predicted to be involved in cellulose biosynthesis. We also investigated the involvement in cellulose production and biofilm formation of celC gene encoding an endoglucanase (CelC2 that is required for canonical symbiotic root hair infection by Rhizobium leguminosarum bv. trifolii. Results ANU843 celC mutants lacking (ANU843?C2 or overproducing cellulase (ANU843C2+ produced greatly increased or reduced amounts of external cellulose micro fibrils, respectively. Calcofluor-stained cellulose micro fibrils were considerably longer when formed by ANU843?C2 bacteria rather than by the wild-type strain, in correlation with a significant increase in their flocculation in batch culture. In contrast, neither calcofluor-stained extracellular micro fibrils nor flocculation was detectable in ANU843C2+ cells. To clarify the role of cellulose synthesis in Rhizobium cell aggregation and attachment, we analyzed the ability of these mutants to produce biofilms on different surfaces. Alteration of wild-type CelC2 levels resulted in a reduced ability of bacteria to form biofilms both in abiotic surfaces and in planta. Conclusions Our results support a key role of the CelC2 cellulase in cellulose biosynthesis by modulating the length of the cellulose fibrils that mediate firm adhesion among Rhizobium bacteria leading to biofilm formation. Rhizobium cellulose is an essential component of the biofilm polysaccharidic matrix architecture and either an excess or a defect of this “building material” seem to collapse the biofilm structure. These results position cellulose hydrolytic enzymes as excellent anti-biofilm candidates.

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

    Directory of Open Access Journals (Sweden)

    G. Archana

    2009-01-01

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

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

    International Nuclear Information System (INIS)

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

  6. “Item perrexil, mostarda, lechugas et rauanos”. Notas sobre la alimentación de mineros alemanes en Pamplona a finales del siglo XIV (1392

    Directory of Open Access Journals (Sweden)

    Serrano Larráyoz, Fernando

    2008-06-01

    Full Text Available The present article represents an approximation to the food of some German miners settled in Pamplona at the end of the 14th century, to carry out a series of assays intended to determine the kind of metals present in the ore and their actual proportion, with the purpose to verify the profitability of some seams found at Five Villages. Their food accounting for approximately one and a half months, give us first hand information of their habits and of those sharing the table with them. To a certain extent, it is possible to extrapolate these practices to the ones of part of Navarra's salary earners. In them, we could sense certain customs or preferences characteristic of North Europe.

    El presente artículo es una aproximación a la alimentación de unos mineros alemanes que, a finales del siglo XIV, se asientan en Pamplona con el fin de realizar una serie de ensayos (averiguación de los metales que contiene la mena —el mineral metalífero—, y la proporción en que cada uno está con el peso de ella en los que determinar la rentabilidad de algunos filones mineros encontrados en la zona de las Cinco Villas. Las cuentas de los gastos que realizan en alimentación, en aprox. mes y medio, nos acercan de primera mano a los hábitos de estos hombres y de quienes les acompañan en la mesa. Unas prácticas que es posible extrapolar, en cierta medida, a parte de la menestralía navarra, y en las que podemos intuir ciertas costumbres (o gustos propios de la Europa del Norte.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-07-01

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

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

    Science.gov (United States)

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

    2015-01-01

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

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

    OpenAIRE

    Ahmad, Maqshoof; Zahir, Zahir A.; Nazli, Farheen; Akram, Fareeha; Muhammad ARSHAD; KHALID, Muhammad

    2014-01-01

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

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

    OpenAIRE

    Yadegari, M.; H.A. Rahmani; G. Noormohammadi; A. Ayneband

    2008-01-01

    To study the effect of co-inoculation with plant growth-promoting rhizobacteria (PGPR) and Rhizobium, on yield and yield components of common bean (Phaseolus vulgaris L.) cultivars was investigated in 2 consecutive years under field condition of plant growing evidence indicates that soil beneficial bacteria can positively affect symbiotic performance of rhizobia. PGPR strains Pseudomonas fluorescens P-93 and Azospirillum lipoferum S-21 as well as two highly effective Rhizobium strains ...

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

    Scientific Electronic Library Online (English)

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

    2013-12-01

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

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

    Directory of Open Access Journals (Sweden)

    Maqshoof Ahmad

    2013-12-01

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

  13. Mutations inducing an active-site aperture in Rhizobium sp. sucrose isomerase confer hydrolytic activity.

    Science.gov (United States)

    Lipski, Alexandra; Watzlawick, Hildegard; Ravaud, Stéphanie; Robert, Xavier; Rhimi, Moez; Haser, Richard; Mattes, Ralf; Aghajari, Nushin

    2013-02-01

    Sucrose isomerase is an enzyme that catalyzes the production of sucrose isomers of high biotechnological and pharmaceutical interest. Owing to the complexity of the chemical synthesis of these isomers, isomaltulose and trehalulose, enzymatic conversion remains the preferred method for obtaining these products. Depending on the microbial source, the ratio of the sucrose-isomer products varies significantly. In studies aimed at understanding and explaining the underlying molecular mechanisms of these reactions, mutations obtained using a random-mutagenesis approach displayed a major hydrolytic activity. Two of these variants, R284C and F164L, of sucrose isomerase from Rhizobium sp. were therefore crystallized and their crystal structures were determined. The three-dimensional structures of these mutants allowed the identification of the molecular determinants that favour hydrolytic activity compared with transferase activity. Substantial conformational changes resulting in an active-site opening were observed, as were changes in the pattern of water molecules bordering the active-site region. PMID:23385465

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

    Directory of Open Access Journals (Sweden)

    2008-01-01

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

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

    Science.gov (United States)

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

    2006-05-01

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

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

    Science.gov (United States)

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

    2004-03-01

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

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

    DEFF Research Database (Denmark)

    Rosendahl, Lis

    1984-01-01

    Bleeding sap composition, dry matter production and N distribution in pea (P. sativum L. cv. Bodil) grown with and without nitrate and nodulated with either R. leguminosarum strain 128c53 or strain 1044 were compared. Nitrate increased the total dry matter production of both symbioses, but...... relative to the total N-accumulation was greater with strain 128c53 due to a higher production of nodule tissue. The root bleeding sap of the symbiosis with the greater yield (strain 1044) contained high levels of asparagine and aspartic acid. In the 128c53 symbiosis, glutamine plus homoserine accounted...... for a higher percentage of the organic solutes transporting newly assimilated N from the root system than in the association with 1044. The Rhizobium strain effect on amino compound composition of the bleeding sap may indicate an influence of the bacteroids on either the N-assimilatory enzyme system...

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

    Directory of Open Access Journals (Sweden)

    Tadeusz Zaj?c

    2013-07-01

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

  19. Screening possible mechanisms mediating cadmium resistance in Rhizobium leguminosarum bv. viciae isolated from contaminated Portuguese soils.

    Science.gov (United States)

    Pereira, Sofia Isabel Almeida; Lima, Ana Isabel Gusmão; Figueira, Etelvina Maria de Almeida Paula

    2006-08-01

    Environment heavy-metal contamination is now widespread. Soils may become contaminated from a variety of anthropogenic sources, such as smelters, mining, industry, and application of metal-containing pesticides and fertilizers. Soil microorganisms are very sensitive to moderate heavy-metal concentrations. Therefore, the present work was designed to screen possible mechanisms involved in Rhizobium's Cd resistance; with this purpose, we determined the tolerance levels of several isolates originated from sites with different heavy-metal contamination. Whole-cell-soluble proteins and plasmid profiles were analyzed. We also determined Cd cell concentrations and lipopolysaccharide (LPS) amounts. Results showed different tolerances among Rhizobium isolates; according to their maximum resistance level, isolates were divided in four groups: sensitive (0-125 microM CdCl(2)), moderately tolerant (125-210 microM CdCl(2)), tolerant (250-500 microM CdCl(2)), and extremely tolerant (> or =750 microM CdCl(2)). Intracellular Cd concentrations were lower when compared to wall-bound Cd. Unexpectedly, extremely tolerant isolates accumulated higher levels of metal, suggesting the presence of intracellular agents that prevent metal interfering with important metabolic pathways. The electrophoretic patterns of whole-cell-soluble proteins evidenced cadmium as an inducer of protein metabolism alterations, which were more evident in some polypeptides. Plasmid profiles also showed differences; most tolerant isolates presented two plasmids with molecular weights of 485 and 415 kb, indicating that extrachromosomal DNA may be involved in cadmium resistance. LPS showed to be a common mechanism of resistance. However, the degree of tolerance conferred by LPS is not enough to support tolerance to the higher levels of stress imposed. Presence of other resistance mechanisms is currently being investigated. PMID:16897308

  20. Curriculum Development and Education for Living Together: Conceptual and Managerial Challenges in Africa. Final Report of the Seminar (Nairobi, Kenya, June 25-29, 2001) (Developpement du Curriculum et Education pour Vivre Ensemble: Problemes de Concepts et de Gestion en Afrique. Rapport Final du Seminaire (Nairobi, Kenya, 25-29 Juin 2001).

    Science.gov (United States)

    Aglo, John, Ed.; Lethoko, Mankolo, Ed.

    The Nairobi, Kenya, seminar sought to analyze existing official school curricula from the vantage point of their potential contribution to learning and to address the issue of curriculum management with a view to improving the capacity of basic schooling to contribute to enhanced social cohesion. This final report is divided into four parts. Part…

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

    Science.gov (United States)

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

    1996-06-01

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

  2. Mathématiques, Mind et Geist.

    Directory of Open Access Journals (Sweden)

    Jean-Michel Salanskis

    2004-04-01

    Full Text Available L’article est une exploration systématique de la dualité des figures du Mind et du Geist, le premier étant entendu comme l’esprit en tant que partie de la nature scientifiquement objectivable, le second comme l’esprit en tant qu’acteur immatériel insaisissable de la pensée. De plus, cette dualité est étudiée du point de vue de l’interférence de la mathématique avec elle, dans plusieurs contextes. Sont ainsi successivement analysés : le conflit entre les deux « modèles » du Mind, le computationnaliste et le dynamiciste; la définition philosophique et la définition épistémologique du Geist ; le jeu entre Mind et Geist dans les recherches cognitives contemporaines ; l’ambivalence de la logique et des mathématiques vis-à-vis de l’opposition Mind/Geist. Dans la partie finale, on propose une définition personnelle du Geist–en termes d’adresse et de sujet–dont dérive une détermination du Mind. Revenant sur ces nouvelles bases à l’interférence avec la mathématique, on conclut sur la question essentielle et délicate de la paramétrisation de la conscience.This paper systematically investigates the conflicting figures of Mind and Geist : Mind has to be understood as some part of nature likely to become the object of science, while Geist names the unmaterial unseizable protagonist of thought. Further, the opposition of the two figures is studied in the light of the way mathematics interfere with it, in several contexts. This leads to following analyses : how computational and dynamicist models of Mind compete within cognitive science; how Geist may be defined philosophically and epistemologically ; how Mind and Geist differently come to be considered or to be aimed at within contemporary cognitive research ; how mathematics and logic play an ambivalent part with respect to the Mind/Geist opposition. In the final section of the paper, a personal definition of the Geist–in terms of address and subject–is proposed, which also leads to some conceptual determination of the Mind. Coming back to the interference with mathematics on this new basis, the paper concludes by an examination of the difficult question of the parametrization of consciousness.

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

    International Nuclear Information System (INIS)

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2009-07-01

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

  5. Gérer et alerter

    Directory of Open Access Journals (Sweden)

    Valérie November

    2009-03-01

    Full Text Available Sur la base de deux événements d’inondation ayant touché récemment, dans des contextes politiques, organisationnels et hydrologiques bien différents, de nouveaux quartiers d’habitation, cet article rend compte des pratiques des acteurs impliqués dans des situations d’alerte et de crise en Suisse. Le recensement des acteurs – à travers leur rôle et leur place dans les mécanismes de préparation, d’alerte et de gestion –, ainsi que l’inventaire des documents mobilisés par ceux-ci, ont été réalisés dans les deux cas. Cette analyse a permis d’évaluer la gestion des événements, de déceler les changements organisationnels qui ont suivi les crises et de connaître la conception et le degré de formalisation du risque dont étaient dotés les différents acteurs avant et après les inondations. Plus encore, l’analyse a documenté les nouveaux processus d’alerte et de prévision qui ont été mis en place suite aux événements. Il s’avère ainsi que les épisodes d’inondation agissent de façon décisive sur la production de connaissances, à un degré variable selon les acteurs. Ces épisodes révèlent aussi parfois l’existence de connaissances « en attente » qui ne sont pas encore intégrées dans les procédures institutionnelles. Tant du point de vue de la prévision que de la gestion de la crise, ils permettent aussi de tester les canaux de l’information et de combler les déficits d’organisation, de collaboration et de sécurisation des dispositifs de communication. En outre, les risques et les crises liés aux inondations modifient les dynamiques et les politiques territoriales, conséquences du réajustement des réseaux d’acteurs. La mise en place de dispositifs d’intervention et de gestion de crise se montre cependant plus efficace que la refonte des dispositifs d’aménagement, généralement longue. Toutefois, la mémoire des événements se dégradant avec le temps, une inscription territoriale du risque s’avère nécessaire.Based on two flood events that recently affected new housing areas in very different political, organisational and hydrological contexts, this article examines the practices of actors involved in emergency and crisis situations in Switzerland. In both cases, the actors are identified – through their role and their position in the various procedures related to crisis management – and an inventory is made of the documents used. The study examines how the flood events were managed, identifies the organisational changes that followed the crises, and determines how the risk was conceived and to what extent it was formalised by the different actors both before and after the floods. Finally new forecasting and warning procedures that were set up following the events are described. The study shows that floods have a decisive impact on the production of knowledge, but that this phenomenon varies according to the actors. Events such as floods also sometimes reveal the existence of "latent" knowledge, or knowledge that is available but has not yet been integrated into institutional procedures. In terms of both forecasting and crisis management, these events also provide the opportunity to test information channels and to identify and correct any problems relating to organisation, cooperation or the reliability of means of communication. Among other things, the risks and crises related to flooding modify the dynamics and policies of the local area as a result of readjustments in the networks of actors. The introduction of emergency and crisis management measures appears more effective, however, than the reorganisation of planning and development procedures, a process which generally takes a lot longer. Nevertheless, since the recollection of events tends to fade with time, it is important that risks find a more concrete form of spatial expression on the landscape.

  6. Nodulation inhibition by Rhizobium leguminosarum multicopy nodABC genes and analysis of early stages of plant infection.

    OpenAIRE

    Knight, C D; Rossen, L.; Robertson, J.G.; Wells, B.; Downie, J. A.

    1986-01-01

    During analysis of early events in the infection and nodulation of Vicia hirsuta roots inoculated with normal and mutant strains of Rhizobium leguminosarum and strains containing cloned nodulation (nod) genes, a number of novel observations were made. (i) Alternating zones of curled and straight root hairs were seen on roots of V. hirsuta inoculated with the wild-type strain of R. leguminosarum. This phasing of root hair curling was not seen if plants were grown under continuous light or cont...

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

    Science.gov (United States)

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

    2005-01-01

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

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

    OpenAIRE

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

    2014-01-01

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

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

    OpenAIRE

    Anollés, Gustavo Caetano; Favelukes, Gabriel

    1986-01-01

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

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

    OpenAIRE

    Cheol Woo Lee Park; Yolanda Navarro de Navarro

    2010-01-01

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

  11. 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...

  12. Complete genome sequence of Rhizobium leguminosarum bv. trifolii strain WSM1325, an effective microsymbiont of annual Mediterranean clovers.

    OpenAIRE

    Reeve, Wayne; O’Hara, Graham; Chain, Patrick; Ardley, Julie; Bräu, Lambert; Nandesena, Kemanthi; Tiwari, Ravi; Copeland, Alex; Nolan, Matt; Han, Cliff; Brettin, Thomas; Land, Miriam; Ovchinikova, Galina; Ivanova, Natalia; Mavromatis, Konstantinos

    2010-01-01

    Rhizobium leguminosarum bv trifolii is a soil-inhabiting bacterium that has the capacity to be an effective nitrogen fixing microsymbiont of a diverse range of annual Trifolium (clover) species. Strain WSM1325 is an aerobic, motile, non-spore forming, Gram-negative rod isolated from root nodules collected in 1993 from the Greek Island of Serifos. WSM1325 is produced commercially in Australia as an inoculant for a broad range of annual clovers of Mediterranean origin due to its superior attrib...

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

    OpenAIRE

    Esther Boboye, Bolatito; Ajayi, George Olarewaju

    2012-01-01

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

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

    OpenAIRE

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

    2015-01-01

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

  15. Physiological roles of glutamine synthetases I and II in ammonium assimilation in Rhizobium sp. 32H1.

    OpenAIRE

    Ludwig, R A

    1980-01-01

    The two glutamine synthetases of Rhizobium sp. 32H1 appear to be structurally and functionally distinct. Glutamine synthetase I was reversibly adenylylated, and its synthesis was repressed only twofold by ammonium. When in the unadenylylated configuration, it was the enzyme which allowed the organism to grow, albeit marginally, on ammonium as a nitrogen source. There is no evidence to suggest that the second enzyme, glutamine synthetase II, is regulated by adenylylation. However, this enzyme ...

  16. 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

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

    OpenAIRE

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

    1985-01-01

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

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

    International Nuclear Information System (INIS)

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

  19. Influence of host cultivars and Rhizobium species on the growth and symbiotic performance of Phaseolus vulgaris under salt stress.

    Science.gov (United States)

    Bouhmouch, Ilham; Souad-Mouhsine, Bouchra; Brhada, Fatiha; Aurag, Jamal

    2005-10-01

    In order to study the effect of salt stress on the Rhizobium-common bean symbiosis, we investigated the response of both partners, separately and in symbiosis. The comparison of the behaviour of five cultivars of Phaseolus vulgaris differing in seed colour, growing on nitrates and different concentrations of NaCl, showed genotypic variation with respect to salt tolerance. Coco Blanc was the most sensitive cultivar, whereas SMV 29-21 was the most tolerant one. At the Rhizobium level, two strains previously selected for their salt tolerance were used: Rhizobium tropici strain RP163 and Rhizobium giardinii strain RP161. Their relative growth was moderately decreased at 250mM NaCl, but they were able to grow at a low rate in the presence of 342 mM NaCl. Their viability at the minimal inhibitory concentration was slightly affected. The effect of salinity on Rhizobium-plant association was studied by using the tolerant variety SMV 29-21 and the sensitive one Coco Blanc inoculated separately with both strains. In the absence of salinity, the strains induced a significantly higher number of nodules on the roots of the cultivar SMV 29-21 compared to those of Coco Blanc. Concerning effectiveness, both strains were similarly effective with SMV 29-21, but not with Coco Blanc. In the presence of salinity, Coco Blanc was more severely affected when associated with RP163 than with RP161. Salinity affected the nodulation development more than it affected the infection steps. Neither of the two strains was able to nodulate SMV 29-21 under saline conditions, in spite of the fact that this was considered the most salt-tolerant variety. The unsuccessful nodulation of SMV 29-21 could be related to the inhibition by salt of one or more steps of the early events of the infection process. In conclusion, N-fixing plants were found to be more sensitive to salt stress than those depending on mineral nitrogen. Evidence presented here suggests that a best symbiotic N2 fixation under salinity conditions could be achieved if both symbiotic partners, as well as the different steps of their interaction (early events, nodule formation, activity, etc.), are all tolerant to this stress. PMID:16255168

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

    Directory of Open Access Journals (Sweden)

    SRI PURWANINGSIH

    2005-07-01

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

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

    International Nuclear Information System (INIS)

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

  2. 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.

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

    Science.gov (United States)

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

    1993-11-01

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

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

    Science.gov (United States)

    Li, D M; Alexander, M

    1986-10-01

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

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

    Science.gov (United States)

    Kaluza, K; Hahn, M; Hennecke, H

    1985-05-01

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

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

    Science.gov (United States)

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

    2015-08-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2000-07-01

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

  8. 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

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

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

  12. Evaluación de diferentes sistemas de fermentación para la producción de ácido indolacético por Rhizobium sp

    Directory of Open Access Journals (Sweden)

    Beatriz Altuna

    2006-01-01

    Full Text Available Las investigaciones relacionadas con la producción microbiológica de hormonas de crecimiento vegetal tienen hoy amplia actualidad, no sólo por los efectos beneficiosos que éstas producen en diversos cultivos, sino también por su alta compatibilidad con el ambiente. Un ejemplo interesante de ello lo constituye el ácido indolacético. En esta investigación se describe la producción de AIA en un cultivo intermitente con una cepa de Rhizobium sp. Pudo comprobarse que la relación de formación biomasa-producto obedece a una clasificación del tipo "parcialmente asociada". La velocidad o rapidez específica de proliferación ("crecimiento" máxima fue de 0.12 h-1, alcanzando la concentración de AIA valores de 340 mg/l. Dos sistemas de biorreacción del tipo intermitente incrementado ("fed-batch" fueron evaluados, mostrando el sistema de alimentación exponencial ventajas significativas en el proceso al obtenerse valores de productividades máximas de 16 mg/l-h, es decir, incrementos en esta respuesta del 60 % y concentraciones de AIA máximas de 467 mg/l.

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

    Science.gov (United States)

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

    2015-03-01

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

  14. Optimization of culture conditions for exopolysaccharides production in Rhizobium sp. using the response surface method

    Scientific Electronic Library Online (English)

    Flávia, Pereira Duta; Francisca, Pessôa de França; Léa Maria, de Almeida Lopes.

    2006-07-15

    Full Text Available The combined effects of the processing parameters for exopolysaccharides production by Rhizobium sp. was studied using the experimental design and response surface methodology. The experiments were carried out using a fermenter with 20 L capacity, as the reactor. All processing parameters were onlin [...] e monitored. The temperature [(30 ± 1)ºC] and pH value (7.0 ± 0.1) were kept constant throughout the experimental time. As statistical tools, a complete 2³ factorial planning with central point and response surface were used to study the interactions among three relevant variables of the fermentation process: calcium carbonate concentration, aeration and agitation. The processing parameters setup for reaching a maximum response for exopolysaccharides production was obtained when applying the highest values for calcium carbonate concentration (1.1 g/L), aeration (1.3 vvm) and agitation (800 rpm). In addition, the combination of these optimum processing parameters yielded Y P/S (g/g) = 0.35.

  15. Effects of high temperature on survival, symbiotic performance and genomic modifications of bean nodulating Rhizobium strains / Sobrevivência, fixação de nitrogênio e modificações genéticas em estirpes de Rhizobium sp. efetivas na nodulação do feijoeiro, expostas à altas temperaturas

    Scientific Electronic Library Online (English)

    Patrícia P., Pinto; Ruy, Raposeiras; Andrea M., Macedo; Lucy, Seldin; Edilson, Paiva; Nadja M.H., Sá.

    1998-10-01

    Full Text Available Altas temperaturas podem afetar a sobrevivência, estabelecimento e as propriedades simbióticas em estirpes de Rhizobium. As estirpes capazes de nodular o feijoeiro têm sido consideradas particularmente sensíveis, porque nessas estirpes é comum a ocorrência de recombinações e/ou deleções genômicas co [...] mprometendo, muitas vezes, a sua utilização como inoculantes. Neste trabalho, procurou-se avaliar a capacidade de crescimento e sobrevivência em temperaturas elevadas de estirpes de Rhizobium efetivas na fixação de nitrogênio no feijoeiro isoladas dos cerrados, bem como avaliar suas características fenotípicas e genotípicas após choque térmico. A capacidade de sobrevivência à temperaturas elevadas, avaliada após choques térmicos sucessivos (45ºC por 4 horas) mostrou ser uma característica própria de cada estirpe, independente de sua termotolerância, que aparentemente foi mais acentuada nas estirpes de R. tropici. Algumas estirpes de R. leguminosarum bv. phaseoli mostraram alterações significativas (Duncan 5% de probabilidade) nas suas características fenotípicas (produção de matéria seca) após choques térmicos e nos seus padrões genômicos evidenciados pela técnica de AP-PCR. As estirpes de R. tropici foram aparentemente mais estáveis não sendo detectadas alterações fenotípicas significativas e com exceção da estirpe FJ2.21, após choque térmico e inoculação na planta hospedeira, mantiveram o padrão genômico original. Abstract in english High temperatures can affect the survival, establishment and symbiotic properties of Rhizobium strains. Bean nodulating Rhizobium strains are considered particularly sensitive because on this strains genetic recombinations and/or deletions occur frequently, thus compromising the use of these bacteri [...] a as inoculants. In this study R. tropici and R. leguminosarum bv. phaseoli strains isolated from Cerrado soils were exposed to thermal stress and the strains’ growth, survival and symbiotic relationships as well as alterations in their genotypic and phenotypic characteristics were analyzed. After successive thermal shocks at 45ºC for four hours, survival capacity appeared to be strain-specific, independent of thermo-tolerance and was more apparent in R. tropici strains. Certain R. leguminosarum bv. phaseoli strains had significant alterations in plant dry weight and DNA patterns obtained by AP-PCR method. R. tropici strains (with the exception of FJ2.21) were more stable than R. leguminosarum bv. phaseoli strains because no significant phenotypic alterations were observed following thermal treatments and they maintained their original genotypic pattern after inoculation in plants.

  16. Interação entre cultivares, estirpes comerciais de Rhizobium meliloti e fungicidas no incremento da produção de alfafa / Interactions of cultivars, commercial strains of Rhizobium meliloti and fungicides on the production of alfalfa

    Scientific Electronic Library Online (English)

    Patrícia Perondi Anchão, Oliveira; Siu Mui, Tsai; Moacyr, Corsi; María Del Pilar, Díaz.

    1999-03-01

    Full Text Available A cultura da alfafa (Medicago sativa) é importante para a produção animal, por sua alta qualidade nutritiva, alto potencial de produção e sucesso na fixação de nitrogênio, através da simbiose com o Rhizobium meliloti, dispensando o uso de adubação nitrogenada. Neste trabalho objetivou-se selecionar [...] estirpes comerciais de R. meliloti (SEMIA-116, SEMIA-134 e SEMIA-135) em relação às cultivares de alfafa Flórida 77, Pioneer 5929, CUF 101 e Crioula, e avaliar os fungicidas Iprodione e Thiram em tratamento de semente e solo na cultivar Crioula. Não houve interação entre as estirpes de R. meliloti e as cultivares de alfafa quanto à produção de matéria seca, e as plantas infestadas com a SEMIA-116 apresentaram maior número de nódulos. Houve interações entre os diferentes tipos e doses de fungicidas e as estirpes de R. meliloti testadas. A estirpe SEMIA-116 apresentou superioridade, representada pela maior produção de biomassa e número de nódulos. Pelos resultados obtidos, não se recomenda a inoculação da estirpe SEMIA-135, quando em associação com o fungicida Iprodione, em solo ou semente. Abstract in english The cultivation of alfalfa (Medicago sativa) is not only important because of its nutrient, content, but also for its high productivity and its ability to fix nitrogen through its association with Rhizobium meliloti. To better understand this symbiotic association, the interaction between R. melilot [...] i strains SEMIA-116, SEMIA-134 and SEMIA-135 with different cultivars of alfalfa Florida 77, Pioneer 5929, CUF 101 and Crioula was evaluated. In addition to the above treatments, the fungicides Iprodione and Thiram were used with the cultivar Crioula to study their effects on the alfalfa/Rhizobium interaction. Plants inoculated with SEMIA-116 had a greater number of nodules. However, no significant difference in the production of plant dry matter was observed between the various Rhizobium strains and the alfalfa cultivars tested. In the presence of the tested fungicides, the Crioula/SEMIA-116 association showed superior biomass production and number of nodules. Results obtained in this study suggest that SEMIA-135 should not be used as an inoculum for alfalfa when Iprodione is used either as a soil or seed treatment.

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

    Directory of Open Access Journals (Sweden)

    Ormeño-Orrillo Ernesto

    2012-12-01

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

  18. Effects of high temperature on survival, symbiotic performance and genomic modifications of bean nodulating Rhizobium strains Sobrevivência, fixação de nitrogênio e modificações genéticas em estirpes de Rhizobium sp. efetivas na nodulação do feijoeiro, expostas à altas temperaturas

    Directory of Open Access Journals (Sweden)

    Patrícia P. Pinto

    1998-10-01

    Full Text Available High temperatures can affect the survival, establishment and symbiotic properties of Rhizobium strains. Bean nodulating Rhizobium strains are considered particularly sensitive because on this strains genetic recombinations and/or deletions occur frequently, thus compromising the use of these bacteria as inoculants. In this study R. tropici and R. leguminosarum bv. phaseoli strains isolated from Cerrado soils were exposed to thermal stress and the strains’ growth, survival and symbiotic relationships as well as alterations in their genotypic and phenotypic characteristics were analyzed. After successive thermal shocks at 45ºC for four hours, survival capacity appeared to be strain-specific, independent of thermo-tolerance and was more apparent in R. tropici strains. Certain R. leguminosarum bv. phaseoli strains had significant alterations in plant dry weight and DNA patterns obtained by AP-PCR method. R. tropici strains (with the exception of FJ2.21 were more stable than R. leguminosarum bv. phaseoli strains because no significant phenotypic alterations were observed following thermal treatments and they maintained their original genotypic pattern after inoculation in plants.Altas temperaturas podem afetar a sobrevivência, estabelecimento e as propriedades simbióticas em estirpes de Rhizobium. As estirpes capazes de nodular o feijoeiro têm sido consideradas particularmente sensíveis, porque nessas estirpes é comum a ocorrência de recombinações e/ou deleções genômicas comprometendo, muitas vezes, a sua utilização como inoculantes. Neste trabalho, procurou-se avaliar a capacidade de crescimento e sobrevivência em temperaturas elevadas de estirpes de Rhizobium efetivas na fixação de nitrogênio no feijoeiro isoladas dos cerrados, bem como avaliar suas características fenotípicas e genotípicas após choque térmico. A capacidade de sobrevivência à temperaturas elevadas, avaliada após choques térmicos sucessivos (45ºC por 4 horas mostrou ser uma característica própria de cada estirpe, independente de sua termotolerância, que aparentemente foi mais acentuada nas estirpes de R. tropici. Algumas estirpes de R. leguminosarum bv. phaseoli mostraram alterações significativas (Duncan 5% de probabilidade nas suas características fenotípicas (produção de matéria seca após choques térmicos e nos seus padrões genômicos evidenciados pela técnica de AP-PCR. As estirpes de R. tropici foram aparentemente mais estáveis não sendo detectadas alterações fenotípicas significativas e com exceção da estirpe FJ2.21, após choque térmico e inoculação na planta hospedeira, mantiveram o padrão genômico original.

  19. Isolation of Insertion Sequence ISRLdTAL1145-1 from a Rhizobium sp. (Leucaena diversifolia) and Distribution of Homologous Sequences Identifying Cross-Inoculation Group Relationships †

    OpenAIRE

    Rice, Douglas J.; Somasegaran, Padma; MacGlashan, Kathryn; Bohlool, B. Ben

    1994-01-01

    Insertion sequence (IS) element ISRLdTAL1145-1 from Rhizobium sp. (Leucaena diversifolia) strain TAL 1145 was entrapped in the sacB gene of the positive selection vector pUCD800 by insertional inactivation. A hybridization probe prepared from the whole 2.5-kb element was used to determine the distribution of homologous sequences in a diverse collection of 135 Rhizobium and Bradyrhizobium strains. The IS probe hybridized strongly to Southern blots of genomic DNAs from 10 rhizobial strains that...

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

    OpenAIRE

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

    1996-01-01

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

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

    DEFF Research Database (Denmark)

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

    2009-01-01

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

  2. Revision of the taxonomic status of the species Rhizobium lupini and reclassification as Bradyrhizobium lupini comb. nov.

    Science.gov (United States)

    Peix, Alvaro; Ramírez-Bahena, Martha Helena; Flores-Félix, José David; Alonso de la Vega, Pablo; Rivas, Raúl; Mateos, Pedro F; Igual, José M; Martínez-Molina, Eustoquio; Trujillo, Martha E; Velázquez, Encarna

    2015-04-01

    The species Rhizobium lupini was isolated from Lupinus nodules and included in the Approved Lists of Bacterial Names in 1980. Nevertheless, on the basis of the analysis of the type strain of this species available in DSMZ, DSM 30140(T), whose 16S rRNA gene was identical to that of the type strain of Bradyrhizobium japonicum , R. lupini was considered a later synonym of this species. In this study we confirmed that the strain DSM 30140(T) belongs to the species B. japonicum , but also that it cannot be the original strain of R. lupini because this species effectively nodulated Lupinus whereas strain DSM 30140(T) was able to nodulate soybean but not Lupinus. Since the original type strain of R. lupini was deposited into the USDA collection by L. W. Erdman under the accession number USDA 3051(T) we analysed the taxonomic status of this strain showing that although it belongs to the genus Bradyrhizobium instead of genus Rhizobium , it is phylogenetically distant from B. japonicum and closely related to Bradyrhizobium canariense . The type strains R. lupini USDA 3051(T) and B. canariense BTA-1(T) share 16S rRNA, recA and glnII gene sequences with similarities of 99.8%, 96.5% and 97.1%, respectively. They presented a DNA-DNA hybridization value of 36% and also differed in phenotypic characteristics and slightly in the proportions of some fatty acids. Therefore we propose the reclassification of the species Rhizobium lupini as Bradyrhizobium lupini comb. nov. The type strain is USDA 3051(T) (?=?CECT 8630(T)?=?LMG 28514(T)). PMID:25609676

  3. Rhizobium meliloti host range nodH gene determines production of an alfalfa-specific extracellular signal.

    OpenAIRE

    Faucher, C; Maillet, F; Vasse, J; Rosenberg, C; Van Brussel, A A; Truchet, G.; Dénarié, J.

    1988-01-01

    The Rhizobium meliloti nodH gene is involved in determining host range specificity. By comparison with the wild-type strain, NodH mutants exhibit a change in host specificity. That is, although NodH mutants lose the ability to elicit root hair curling (Hac-), infection threads (Inf-), and nodule meristem formation (Nod-) on the homologous host alfalfa, they gain the ability to be Hac+ Inf+ Nod+ on a nonhomologous host such as common vetch. Using root hair deformation (Had) bioassays on alfalf...

  4. Molecular cloning and expression of Rhizobium fredii USDA 193 nodulation genes: extension of host range for nodulation.

    OpenAIRE

    Ramakrishnan, N; Prakash, R K; Shantharam, S; DuTeau, N M; Atherly, A G

    1986-01-01

    DNA hybridization with the cloned nodulation region of Rhizobium meliloti as a probe revealed DNA homology with four HindIII fragments, 12.5, 6.8, 5.2, and 0.3 kilobases (kb) in size, of the symbiotic plasmid pRjaUSDA193. Both hybridization and complementation studies suggest that the common nodulation genes nodABC and nodD of R. fredii USDA 193 are present on the 5.2-kb HindIII and 2.8-kb EcoRI fragments, respectively, of the Sym plasmid. Both fragments together could confer nodulation abili...

  5. Identification and sequence analysis of the Rhizobium meliloti dctA gene encoding the C4-dicarboxylate carrier.

    OpenAIRE

    Engelke, T; Jording, D; Kapp, D.; PÜhler, A.

    1989-01-01

    Transposon Tn5-induced C4-dicarboxylate transport mutants of Rhizobium meliloti 2011 which could be complemented by cosmid pRmSC121 were subdivided into two classes. Class I mutants (RMS37 and RMS938) were defective in symbiotic C4-dicarboxylate transport and in nitrogen fixation. They were mutated in the structural gene dctA, which codes for the C4-dicarboxylate carrier. Class II mutants (RMS11, RMS16, RMS17, RMS24, and RMS31) expressed reduced activity in symbiotic C4-dicarboxylate transpor...

  6. Deduced products of C4-dicarboxylate transport regulatory genes of Rhizobium leguminosarum are homologous to nitrogen regulatory gene products.

    OpenAIRE

    Ronson, C W; Astwood, P M; Nixon, B T; Ausubel, F. M.

    1987-01-01

    We have sequenced two genes dctB and dctD required for the activation of the C4-dicarboxylate transport structural gene dctA in free-living Rhizobium leguminosarum. The hydropathic profile of the dctB gene product (DctB) suggested that its N-terminal region may be located in the periplasm and its C-terminal region in the cytoplasm. The C-terminal region of DctB was strongly conserved with similar regions of the products of several regulatory genes that may act as environmental sensors, includ...

  7. 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-...

  8. Quorum Sensing in Rhizobium sp. Strain NGR234 Regulates Conjugal Transfer (tra) Gene Expression and Influences Growth Rate

    OpenAIRE

    He, Xuesong; Chang, William; Pierce, Deanne L.; Seib, Laura Ort; Wagner, Jennifer; Fuqua, Clay

    2003-01-01

    Rhizobium sp. strain NGR234 forms symbiotic, nitrogen-fixing nodules on a wide range of legumes via functions largely encoded by the plasmid pNGR234a. The pNGR234a sequence revealed a region encoding plasmid replication (rep) and conjugal transfer (tra) functions similar to those encoded by the rep and tra genes from the tumor-inducing (Ti) plasmids of Agrobacterium tumefaciens, including homologues of the Ti plasmid quorum-sensing regulators TraI, TraR, and TraM. In A. tumefaciens, TraI, a L...

  9. Biological Control of Crown Gall on Grapevine and Root Colonization by Nonpathogenic Rhizobium vitis Strain ARK-1

    OpenAIRE

    Kawaguchi, Akira

    2013-01-01

    A nonpathogenic strain of Rhizobium vitis ARK-1 was tested as a biological control agent for grapevine crown gall. When grapevine roots were soaked in a cell suspension of strain ARK-1 before planting in the field, the number of plants with tumors was reduced. The results from seven field trials from 2009 to 2012 were combined in a meta-analysis. The integrated relative risk after treatment with ARK-1 was 0.15 (95% confidence interval: 0.07–0.29, P

  10. Role of BacA in Lipopolysaccharide Synthesis, Peptide Transport, and Nodulation by Rhizobium sp. Strain NGR234?

    OpenAIRE

    Ardissone, Silvia; Kobayashi, Hajime; Kambara, Kumiko; Rummel, Coralie; Noel, K. Dale; Walker, Graham C.; Broughton, William J; Deakin, William J.

    2011-01-01

    BacA of Sinorhizobium meliloti plays an essential role in the establishment of nitrogen-fixing symbioses with Medicago plants, where it is involved in peptide import and in the addition of very-long-chain fatty acids (VLCFA) to lipid A of lipopolysaccharide (LPS). We investigated the role of BacA in Rhizobium species strain NGR234 by mutating the bacA gene. In the NGR234 bacA mutant, peptide import was impaired, but no effect on VLCFA addition was observed. More importantly, the symbiotic abi...

  11. [Signaling Systems of Rhizobia (Rhizobiaceae) and Leguminous Plants (Fabaceae) upon the Formation of a Legume-Rhizobium Symbiosis (Review)].

    Science.gov (United States)

    Glyan'ko, A K

    2015-01-01

    Data from the literature and our own data on the participation and interrelation of bacterial signaling Nod-factors and components of the calcium, NADPH-oxidase, and NO-synthase signaling systems of a plant at the preinfection and infectious stages of the formation of a legume-rhizobium symbiosis are summarized in this review. The physiological role of Nod-factors, reactive oxygen species (ROS), calcium (Ca2+), NADPH-oxidase, nitric oxide (NO), and their cross influence on the processes determining the formation of symbiotic structures on the roots of the host plant is discussed. PMID:26596081

  12. Response of chickpea (cicer arietinum L.) to various levels of phosphorus and rhizobium inoculation under rainfed condition

    International Nuclear Information System (INIS)

    A field experiment was conducted to evaluate the effect of phosphorus (P) levels and Rhizobium inoculation on yield-components and grain-yield of (chickpea c.v. NIFA-88) under rain fed conditions at Arid Zone Research Institute, Dera Ismail Khan, during 2003- 04. The treatments consisted of P levels; 0, 30, 60 and 90 kg ha-I, with and without inoculum. A basal dose of 20 kg ha-l nitrogen was applied just before sowing, at the time of seedbed preparation. The experiment was laid out according to the randomized complete block design, with three replications. The results showed significant variation in number of pods per plant, 1000 seed weight and grain yield, with the application of P and Rhizobium inoculum. The maximum number of pods per plant (25.00) was recorded in the plots receiving 60 kg P/sub 2/ O/sub 5/ h a/sup -l/ plus inoculum, but was statistically at par with the pods produced by the treatment of 90 kg P/sub 2/ O/sub 5/ ha-l plus inoculum (24.67). Phosphorus levels plus inoculum gave 11.87 percent increased number of pods per plant over mere P levels. Similarly, the maximum 1000 seed weight of 197.0 g was recorded at the rate 90 and 60 kg P/sub 2/O/sub 5/ ha-1 plus inoculum and 90 kg P/sub 2/ O/sub 5/ ha-l alone. The highest grain-yield of 1,317 kg ha/sup -l/ was obtained from the treatments where P was applied at the rate 90 and 60 kg ha-I with inoculum. The grain yield was increased 8.54 percent when P levels were applied with inoculums, as compared to Palone, on average basis. Hence, it can be concluded from the study that (I) Rhizobium inoculum application alone can increase yield, and (II) 60 kg P/sub 2/ O/sub 5/ ha-l is the most economical dose to be used with Rhizobium inoculum for obtaining higher grain-yield of chickpea. (author)

  13. Poly-3-Hydroxybutyrate Degradation in Rhizobium (Sinorhizobium) meliloti: Isolation and Characterization of a Gene Encoding 3-Hydroxybutyrate Dehydrogenase

    OpenAIRE

    Aneja, P.; Charles, T.C.

    1999-01-01

    We have cloned and sequenced the 3-hydroxybutyrate dehydrogenase-encoding gene (bdhA) from Rhizobium (Sinorhizobium) meliloti. The gene has an open reading frame of 777 bp that encodes a polypeptide of 258 amino acid residues (molecular weight 27,177, pI 6.07). The R. meliloti Bdh protein exhibits features common to members of the short-chain alcohol dehydrogenase superfamily. bdhA is the first gene transcribed in an operon that also includes xdhA, encoding xanthine oxidase/dehydrogenase. Tra...

  14. Flavonoid-Inducible Modifications to Rhamnan O Antigens Are Necessary for Rhizobium sp. Strain NGR234-Legume Symbioses

    OpenAIRE

    Broughton, W J; Hanin, M.; Reli?, B.; Kopciñska, J.; Golinowski, W.; ?im?ek, ?.; Ojanen-Reuhs, T; Reuhs, B.; Marie, C.; Kobayashi, H.; Bordogna, B.; Le Quéré, A.; Jabbouri, S; Fellay, R.; Perret, X.

    2006-01-01

    Rhizobium sp. strain NGR234 produces a flavonoid-inducible rhamnose-rich lipopolysaccharide (LPS) that is important for the nodulation of legumes. Many of the genes encoding the rhamnan part of the molecule lie between 87° and 110° of pNGR234a, the symbiotic plasmid of NGR234. Computational methods suggest that 5 of the 12 open reading frames (ORFs) within this arc are involved in synthesis (and subsequent polymerization) of l-rhamnose. Two others probably play roles in the transport of carbo...

  15. Production of Poly &beta-Hydroxybutyric Acid (PHB by Rhizobium elti and Pseudomonas stutzeri

    Directory of Open Access Journals (Sweden)

    Elsayed B. Belal

    2013-11-01

    Full Text Available The amount of chemosynthetic plastic waste increases every year and exact time for its degradation is unknown. Two poly &beta-Hydroxybutyric producing bacteria from different microbial sources were isolated and characterized for their morphological, biochemical properties. Based on their 16S rDNA, they were identified as Rhizobium elti E1 and Pseudomonas stutzeri E114. The bacterial strains were screened for PHB production and compared for the intensity of fluorescence using Nile red staining methods. PHB production conditions were optimized with different carbon and nitrogen sources, the highest PHB production was observed with mannitol, sucrose and ammonium sulphate by R. elti and P. stutzeri, respectively. Regarding incubation time as well as temperature and pH, optimum PHB production conditions were 48 h, 30?C and 7, respectively. R. elti P. stutzeri are capable of accumulating appreciable levels of PHB from glucose, xylose, lactose, whey, molasses, sugar cane bagasse, rice straw hydroysate when 2% from all substrates were used an alternative carbon for the PHB production. Ammonium sulphate was the best nitrogen source. C/N ratio was also one of the factors that affected the production of PHB. The ratio of C/N that reaches 20:1 was considered the best ratio to produce the highest production of PHB. The highest yield of PHB was done by P. stutzeri more than R. elti. The present study provide the useful data about the optimized conditions for PHB production by R. elti and P. stutzeri that can be utilized for industrial production of PHB, a fast emerging alternative of non biodegradable plastics.

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

    Science.gov (United States)

    2011-01-01

    Background The rhizosphere is the microbe-rich zone around plant roots and is a key determinant of the biosphere's productivity. Comparative transcriptomics was used to investigate general and plant-specific adaptations during rhizosphere colonization. Rhizobium leguminosarum biovar viciae was grown in the rhizospheres of pea (its legume nodulation host), alfalfa (a non-host legume) and sugar beet (non-legume). Gene expression data were compared to metabolic and transportome maps to understand adaptation to the rhizosphere. Results Carbon metabolism was dominated by organic acids, with a strong bias towards aromatic amino acids, C1 and C2 compounds. This was confirmed by induction of the glyoxylate cycle required for C2 metabolism and gluconeogenesis in all rhizospheres. Gluconeogenesis is repressed in R. leguminosarum by sugars, suggesting that although numerous sugar and putative complex carbohydrate transport systems are induced in the rhizosphere, they are less important carbon sources than organic acids. A common core of rhizosphere-induced genes was identified, of which 66% are of unknown function. Many genes were induced in the rhizosphere of the legumes, but not sugar beet, and several were plant specific. The plasmid pRL8 can be considered pea rhizosphere specific, enabling adaptation of R. leguminosarum to its host. Mutation of many of the up-regulated genes reduced competitiveness for pea rhizosphere colonization, while two genes specifically up-regulated in the pea rhizosphere reduced colonization of the pea but not alfalfa rhizosphere. Conclusions Comparative transcriptome analysis has enabled differentiation between factors conserved across plants for rhizosphere colonization as well as identification of exquisite specific adaptation to host plants. PMID:22018401

  17. Optimización de las condiciones de fermentación para la producción de polihidroxibutirato por Rhizobium tropici

    Directory of Open Access Journals (Sweden)

    Yuliet Franco

    2009-01-01

    Full Text Available Los polihidroxialcanoatos (PHAs, son poliésteres acumulados intracelularmente como materiales de reserva de carbono y energía por varios microorganismos. El representante más común de esta familia es el poli-b-hidroxibutirato (PHB. Estos biopolímeros se consideran buenos sustitutos de los plásticos sintéticos derivados del petróleo por ser biodregadrables. Sin embargo, la mayor desventaja para la comercialización de los PHA son sus elevados costos de producción comparados con los plásticos derivados del petróleo. La optimización del proceso de fermentación, es una de las estrategias más utilizadas para reducir estos costos. Este trabajo tuvo como objetivos determinar el valor óptimo de pH inicial de la fermentación para la producción de PHB, así como optimizar las condiciones de agitación y aeración del proceso para el rendimiento producto biomasa y para la acumulación de PHB por la cepa Rhizobium tropici 3. La optimización del pH inicial se realizó en zaranda orbital ajustando el valor entre 6 y 8 y se modeló la relación entre el pH y la concentración de PHB (g · L-1 mediante la utilización de polinomios ortogonales. Se definió que el pH inicial óptimo con el cual se asegura la mayor producción de PHB es 6,58 ± 0,2. La búsqueda de los valores óptimos de agitación-aeración para la producción de PHB y para el rendimiento producto-biomasa, se realizó mediante el empleo de un diseño central compuesto Box-Wilson. Las fermentaciones se realizaron en un fermentador de 7,5 L con 5 L de medio de cultivo optimizado. Se determinó que los valores óptimos para la producción fueron 500 r · min-1 y 1 vvm (volumen de aire por minuto por volumen de medio de cultivo para la agitación y la aeración respectivamente y para el rendimiento producto-biomasa, los valores óptimos fueron 472 r · min-1 y 1,55 vvm.

  18. Detection of Rhizobium meliloti cells in field soil and nodules by polymerase chain reaction.

    Science.gov (United States)

    Watson, R J; Haitas-Crockett, C; Martin, T; Heys, R

    1995-09-01

    A genetically marked Rhizobium meliloti strain, R692, was prepared by insertion of a 1.7-kb DNA segment from Tn903 between the nifHDK and fixABC genes in the nod megaplasmid. This DNA was used as a marker, detectable by polymerase chain reaction (PCR), for the specific identification of bacteria in soil samples and alfalfa nodules. This detection technique was tested by applying different titres of the marked strain to field plots seeded with alfalfa. Samples of soil and nodules were assayed for the presence of the marker DNA fragment by PCR using primers specific to the marker sequence. The experiments revealed that the bacteria could be detected directly in soil containing about 10(3)-10(4) bacteria/g, but greater sensitivity was prevented by potent PCR inhibitors present in the samples. The titre of the bacteria in the soil decreased rapidly after inoculation, dropping about 10-fold per week. Tests of vertical location of the bacteria in soil cores showed that the bacteria were initially dispersed to a depth of 18 cm, and subsequently retained viability in the top 2-8 cm. As few as 10 marked R. meliloti per gram of soil resulted in its establishment at detectable levels in nodules. Application of about 10(4)-10(5) bacteria/g soil was sufficient to give the maximum number of nodules per plant and resulted in 70-90% occupancy by the marked strain. Limited movement of the inoculant was detected by analysis of nodules from plants adjacent to the sites where the bacteria were applied, probably by movement in water. The experiments demonstrated the advantages of PCR for the monitoring of marked microorganisms in the environment. PMID:7585359

  19. Biogeography of Rhizobium radiobacter and distribution of associated temperate phages in deep subseafloor sediments.

    Science.gov (United States)

    Engelhardt, Tim; Sahlberg, Monika; Cypionka, Heribert; Engelen, Bert

    2013-01-01

    Bacteriophages might be the main 'predators' in the marine deep subsurface and probably have a major impact on indigenous microbial communities. To identify their function within this habitat, we have determined their abundance and distribution along the sediment columns of two continental margin and two open ocean sites that were recovered during Leg 201 of the Ocean Drilling Program. For all investigated sites, viral abundance followed the total cell numbers with a virus-to-cell ratio between 1 and 10 in the upper 100?mbsf (meters below seafloor). An increasing ratio of about 20 in deeper layers indicated an ongoing viral production in up to 11?Ma old sediments. We have used Rhizobium radiobacter as the most frequently isolated organism from the deep subsurface with a high in situ abundance to identify the frequency of associated rhizobiophages. In this study, 16S rRNA gene copies of R. radiobacter accounted for up to 5.6% of total bacterial 16S rRNA genes (average: 0.75%) as detected by quantitative PCR. A distinctive distribution was identified for R. radiobacter as indicated by a site-specific arrangement of genetically similar populations. Whole genome information of rhizobiophage RR1-A was used to generate a primer system for quantitative PCR specifically targeting the prophage antirepressor gene, indicative for temperate phages. The quantification of this gene within various sediment horizons showed a contribution of temperate phages of up to 14.3% to the total viral abundance. Thus, the high amount of temperate phages within the sediments and among all investigated isolates indicates that lysogeny is the main viral proliferation mode in deep subsurface populations. PMID:22855213

  20. 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 ?M12 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

  1. Competition among rhizobium species for nodulation of Leucaena leucocephala in two tropical soils

    Energy Technology Data Exchange (ETDEWEB)

    Moawad, H.; Bohlool, B.B.

    1984-07-01

    The successful nodulation of legumes by a Rhizobium strain is determined by the competitve ability of that strain against the mixture of other native and inoculant rhizobia. Competition among six Leucaena rhizobial strains in single and multistrain inoculants were studied. Field inoculation trials were conducted in an oxisol and a mollisol soil, both of which contained indigenous Leucaena-nodulating rhizobia. Strain-specific fluorescent antibodies were used for the identification of the strains in Leucaena nodules. Mixtures of three recommended inoculum strains for Leucaena species (TAL82, TAL582, and TAL1145) were used in peat-based inocula either alone or with one of the three other strains isolated from the sites, B213, B214, and B215. Each of these latter three strains was also used as single-strain inocula to study their competition with the native rhizobia in the two soil systems. In the oxisol soil, strains B213 and B215, when used as single-strain inocula, outcompeted the native rhizobia and formed 92 and 62% of the nodules, respectively. Strain B214 was the least competitive in oxisol soil, where it formed 30% of the nodules, and the best in mollisol soil, where it formed 70% of the nodules. The most successful competitor for nodulation in multistrain inocula was strain TAL1145, which outcompeted native and other inoculum Leucaena rhizobia is both soils. None of the strains in single or multistrain inoculants was capable of completely overcoming the resident rhizobia, which formed 4 to 70% of the total nodules in oxisol soil and 12 to 72% in mollisol soil. No strong relationship was detected between the size of the rhizosphere population of a strain and its successful occupation of nodules. 24 references.

  2. Competition Among Rhizobium spp. for Nodulation of Leucaena leucocephala in Two Tropical Soils.

    Science.gov (United States)

    Moawad, H; Bohlool, B B

    1984-07-01

    The successful nodulation of legumes by a Rhizobium strain is determined by the competitive ability of that strain against the mixture of other native and inoculant rhizobia. Competition among six Leucaena rhizobial strains in single and multistrain inoculants were studied. Field inoculation trials were conducted in an oxisol and a mollisol soil, both of which contained indigenous Leucaena-nodulating rhizobia. Strain-specific fluorescent antibodies were used for the identification of the strains in Leucaena nodules. Mixtures of three recommended inoculum strains for Leucaena spp. (TAL82, TAL582, and TAL1145) were used in peat-based inocula either alone or with one of the three other strains isolated from the sites, B213, B214, and B215. Each of these latter three strains was also used as single-strain inocula to study their competition with the native rhizobia in the two soil systems. In the oxisol soil, strains B213 and B215, when used as single-strain inocula, outcompeted the native rhizobia and formed 92 and 62% of the nodules, respectively. Strain B214 was the least competitive in oxisol soil, where it formed 30% of the nodules, and the best in mollisol soil, where it formed 70% of the nodules. The most successful competitor for nodulation in multistrain inocula was strain TAL1145, which outcompeted native and other inoculum Leucaena rhizobia in both soils. None of the strains in single or multistrain inoculants was capable of completely overcoming the resident rhizobia, which formed 4 to 70% of the total nodules in oxisol soil and 12 to 72% in mollisol soil. No strong relationship was detected between the size of the rhizosphere population of a strain and its successful occupation of nodules. PMID:16346600

  3. Competition Among Rhizobium leguminosarum Strains for Nodulation of Lentils (Lens esculenta).

    Science.gov (United States)

    May, S N; Bohlool, B B

    1983-03-01

    Thirty-one cultures of Rhizobium leguminosarum were screened for effectiveness (C(2)H(2) reduction) on lentils (Lens esculenta). Fluorescent antibodies prepared against three of the most effective strains (Hawaii 5-0, Nitragin 92A3, and Nitragin 128A12) exhibited a high degree of strain specificity; the antibodies reacted strongly with their homologous rhizobia in culture and with bacteroids in nodules. They did not cross-react with one another, and only weakly with 5 of the 47 other R. leguminosarum cultures tested. In competition studies in the growth chamber, whenever strain Nitragin 92A3 was included in the inoculum mixture, it consistently (but not always significantly, P = 0.05) occupied the majority of nodules on all four cultivars used. However, some degree of strain X cultivar interaction was apparent: Hawaii 5-0 was of equal competitiveness (P = 0.05) with Nitragin 92A3 on three of the varieties (Commercial, Tekoa, and Benewah), but inferior (P = 0.01) on the Chilean variety; Nitragin 92A3 completely dominated (P = 0.01) Nitragin 128A12 on all cultivars; and Hawaii 5-0 was of equal competitiveness (P = 0.05) to Nitragin 128A12 on the Chilean variety and more competitive (P = 0.01) on the commercial variety and less so on the other two varieties. In field experiments, Hawaii 5-0 proved of equal competitiveness (P = 0.01) with Nitragin 92A3 in one soil (an Inceptisol) and superior (P Oxisol). Incidence of double-strain occupancy of nodules varied from 0 to 36% in vermiculite, depending on the strains in the mixture and the host variety, and from 0 to 38% in the field, depending on the strains in the mixture and the soil type. The results suggest a close relationship between the competitiveness of a strain and its occurrence in doubly infected nodules. PMID:16346257

  4. Agrice et les tensioactifs

    Directory of Open Access Journals (Sweden)

    Rocher Magali

    2001-03-01

    Full Text Available Agrice, Agriculture pour la chimie et l’énergie, est un groupement d’intérêt scientifique qui a pour objet l’animation, le financement, le suivi et l’évaluation de programmes de recherche et développement portant sur les nouvelles valorisations des produits et coproduits d’origine agricole dans les domaines de l’énergie, de la chimie et des matériaux. Aujourd’hui les programmes de recherche et développement sur les tensioactifs sont renforcés, plus sélectifs et plus directement tournés vers l’industrie et les marchés.

  5. Growth, nodulation and yield of mash bean (Vigna mungo L. as affected by Rhizobium inoculation and soil applied L-tryptophan

    Directory of Open Access Journals (Sweden)

    Muhammad Iqbal Hussain*, Muhammad Javed Akhtar, Hafiz Naeem Asghar and Maqshoof Ahmad

    2011-04-01

    Full Text Available Most of the grain legumes in Pakistan are poorly nodulated either because of low indigenous rhizobialpopulation or due to inefficient strains of native rhizobia. However, improvement in nodulation could be achievedthrough inoculation with effective rhizobial strains. A pot trial was conducted to evaluate the effect of Rhizobiuminoculation along with L-tryptophan (L-TRP, a precursor of indole acetic acid (IAA on growth, yield andnodulation of mash been. The results indicated that Rhizobium inoculation along with L-tryptophan application (6mg kg-1 soil significantly improved plant height (44.6% as compared to control. Different improvements in rootlength (72.4%, oven dry root weight (Five fold, no. of pods plant-1 (86.4%, no. of grains per pod (42.8%, 100-grain weight (18.9% and nitrogen concentration in grains (two fold, was noted as compared with the controlwhere L-TRP was applied @ 2 mg kg-1 soil. There was a significant increase in number of nodules plant-1 (one fold,nodule fresh weight plant-1 (two fold and nodule dry weight plant-1 (four fold with Rhizobium inoculation alongwith L-TRP application @ 2 mg kg-1 soil as compared to Rhizobium inoculation alone. The study showed thatRhizobium inoculation along with L-TRP application could be a better approach for sustainable legume production.

  6. The exopolysaccharide of Rhizobium sp. YAS34 is not necessary for biofilm formation on Arabidopsis thaliana and Brassica napus roots but contributes to root colonization.

    Science.gov (United States)

    Santaella, Catherine; Schue, Mathieu; Berge, Odile; Heulin, Thierry; Achouak, Wafa

    2008-08-01

    Microbial exopolysaccharides (EPSs) play key roles in plant-microbe interactions, such as biofilm formation on plant roots and legume nodulation by rhizobia. Here, we focused on the function of an EPS produced by Rhizobium sp. YAS34 in the colonization and biofilm formation on non-legume plant roots (Arabidopsis thaliana and Brassica napus). Using random transposon mutagenesis, we isolated an EPS-deficient mutant of strain YAS34 impaired in a glycosyltransferase gene (gta). Wild type and mutant strains were tagged with a plasmid-born GFP and, for the first time, the EPS produced by the wild-type strain was seen in the rhizosphere using selective carbohydrate probing with a fluorescent lectin and confocal laser-scanning microscopy. We show for the fist time that Rhizobium forms biofilms on roots of non-legumes, independently of the EPS synthesis. When produced by strain YAS34 wild type, EPS is targeted at specific parts of the plant root system. Nutrient fluctuations, root exudates and bacterial growth phase can account for such a production pattern. The EPS synthesis in Rhizobium sp. YAS34 is not essential for biofilm formation on roots, but is critical to colonization of the basal part of the root system and increasing the stability of root-adhering soil. Thus, in Rhizobium sp. YAS34 and non-legume interactions, microbial EPS is implicated in root-soil interface, root colonization, but not in biofilm formation. PMID:18507672

  7. Heat Curing of a Sym Plasmid in a Fast-Growing Rhizobium sp. That Is Able to Nodulate Legumes and the Nonlegume Parasponia sp

    OpenAIRE

    1983-01-01

    Genes involved in nodulation of both legumes and the nonlegume Parasponia sp., as well as nitrogenase genes, reside on a large plasmid in a fast-growing Rhizobium sp. from Lablab purpureus. This plasmid can be cured by incubation at elevated temperatures and can be mobilized by the P1 group plasmid RP1::Tn501.

  8. Ensifer, Phyllobacterium and Rhizobium species occupy nodules of Medicago sativa (alfalfa) and Melilotus alba (sweet clover) grown at a Canadian site without a history of cultivation

    Science.gov (United States)

    Phage resistant and susceptible bacteria from nodules of alfalfa and sweet clover grown at a site without a known history of cultivation, were identified as Ensifer, Rhizobium and Phyllobacterium species based on sequence analysis of ribosomal (16S and 23S rRNA)and protein encoding (atpD and recA) g...

  9. COINOCULACIÓN DE Canavalia ensiformis (L. D.C. CON Rhizobium Y HONGOS MICORRÍZICOS ARBUSCULARES EN DOS TIPOS DE SUELOS DE CUBA

    Directory of Open Access Journals (Sweden)

    Gloria M. Martín

    2015-01-01

    Full Text Available Para evaluar la respuesta de la canavalia (Canavalia ensiformis (L. D.C. a la coinoculación con cepas de Rhizobium y de hongos micorrízicos arbusculares (HMA, se condujo un experimento en condiciones de microparcelas que contenían suelo Ferralítico Rojo Lixiviado procedente del Departamento de Servicios Agrícolas del INCA, en San José de las Lajas, Mayabeque, y suelo Gley Nodular Ferruginoso procedente de la Estación de Pastos y Forrajes de Cascajal, Villa Clara. Se estudiaron cuatro cepas de Rhizobium (Can 2, Can 3, Can 4 y Can 5 y tres cepas de HMA: Glomus cubense (INCAM 4 y Rhizophagus intraradices (INCAM 11 para el suelo Ferralítico Rojo y Glomus cubense y Funneliformis mosseae (INCAM 2para el suelo Gley Nodular más los correspondientes testigos sin inoculación, para un total de 15 tratamientos por tipo de suelo, los cuales se distribuyeron en un diseño completamente aleatorizado con arreglo factorial (5 x 3 y tres repeticiones. Se evaluaron los indicadores del funcionamiento de la simbiosis micorrízica y el rendimiento de masa seca. Los resultados mostraron que la canavalia respondió positivamente a la coinoculación Rhizobium-HMA en ambos tipos de suelos. El mejor comportamiento de las cepas de Rhizobium se obtuvo con Can 3 para el suelo Ferralítico Rojo y Can 3, Can 4 y Can 5 para suelo Gley Nodular Ferruginoso, y las mejores cepas de HMA fueron, en ese orden, G. cubense y F. mosseae para uno y otro suelo, respectivamente.

  10. Homology of genes for exopolysaccharide synthesis in Rhizobium leguminosarum and effect of cloned exo genes on nodule formation

    International Nuclear Information System (INIS)

    A 5.4 kb BamHI fragment of Rhizobium leguminosarum (R.l.) bv. trifolii TA1 was found to carry genes involved in exopolysaccharide synthesis (exo genes). This fragment was strongly hybridized to the total DNA from DNA from R.l. bv. viciae and bv. phaseoli digested with EcoRI. No homology was found with total DNA of R. melilotic and Rhizobium sp. NGR 234. The exo genes R.l. bv. trifolii TA1 conjugally introduced into R.l. bv. viciae 1302 considerably affected the symbiosis: the nodules induced on vetch were abortive and did not fix nitrogen. On the other hand, Phaseolus beans infected with R.l. bv. trifolii exo genes formed the nitrogen-fixing nodules. It can be conduced that additional copies of exo genes introduced into wild type R.l. strains can disturb the synthesis of acidic exopolysaccharides and affect symbiosis of the plants forming indeterminate nodules, but do not affect symbiosis of the plants forming the determinate nodules. (author). 29 refs, 2 figs, 2 tabs

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

    DEFF Research Database (Denmark)

    SkØt, L.; Hirsch, P. R.

    1986-01-01

    The effect of genetic factors in Rhizobium on host plant biomass production and on the carbon costs of N2 fixation in pea root nodules was studied. Nine strains of Rhizobium leguminosarum were constructed, each containing one of three symbiotic plasmids in combination with one of three different genomic backgrounds. The resulting strains were tested in symbiosis with plants of Pisum sativum using a flow-through apparatus in which nodule nitrogenase activity and respiration were measured simultaneously under steady state conditions. Nodules formed by strains containing the background of JI6015 had the lowest carbon costs of N2 fixation (7.10–8.10 ?mol C/?mol N2), but shoot dry weight of those plants was also smaller than that of plants nodulated by strains with the background of B151 or JI8400. Nodules formed by these two strain types had carbon costs of N2 fixation varying between 11.26 and 13.95 ?mol C/?mol N2. The effect of symbiotic plasmids on the carbon costs was relatively small. A time-course experiment demonstrated that nodules formed by a strain derived from JI6015 were delayed in the onset of nitrogenase activity and had a lower rate of activity compared to nodules induced by a strain with the background of B151. The relationship between nitrogenase activity, carbon costs of N2 fixation and host plant biomass production is discussed.

  12. Identification and Characterization of the Rhizobium sp. Strain GIN611 Glycoside Oxidoreductase Resulting in the Deglycosylation of Ginsenosides

    Science.gov (United States)

    Kim, Eun-Mi; Kim, Juhan; Seo, Joo-Hyun; Park, Jun-Seong; Kim, Duck-Hee

    2012-01-01

    Using enrichment culture, Rhizobium sp. strain GIN611 was isolated as having activity for deglycosylation of a ginsenoside, compound K (CK). The purified heterodimeric protein complex from Rhizobium sp. GIN611 consisted of two subunits with molecular masses of 63.5 kDa and 17.5 kDa. In the genome, the coding sequence for the small subunit was located right after the sequence for the large subunit, with one nucleotide overlapping. The large subunit showed CK oxidation activity, and the deglycosylation of compound K was performed via oxidation of ginsenoside glucose by glycoside oxidoreductase. Coexpression of the small subunit helped soluble expression of the large subunit in recombinant Escherichia coli. The purified large subunit also showed oxidation activity against other ginsenoside compounds, such as Rb1, Rb2, Rb3, Rc, F2, CK, Rh2, Re, F1, and the isoflavone daidzin, but at a much lower rate. When oxidized CK was extracted and incubated in phosphate buffer with or without enzyme, (S)-protopanaxadiol [PPD(S)] was detected in both cases, which suggests that deglycosylation of oxidized glucose is spontaneous. PMID:22020506

  13. Biological nitrogen fixation by Rhizobium sp. native gliricidia (Gliricidia sepium [Jacq.] Kunth ex Walp. under greenhouse conditions

    Directory of Open Access Journals (Sweden)

    Milian Mindiola Pablo Ernesto

    2011-12-01

    Full Text Available

    An experiment was conducted under greenhouse conditions in order to evaluate the association and biological nitrogen fixation (BNF, six native strains of Rhizobium sp isolated from nodules gliricidia and a commercial strain (Rhizobiolc. Suspensions of 106 and 108 cells/mL for each of the strains studied and applied in two separate trials: the first with seeds and the second with seedlings 35 days of age gliricidia. In the seed test is calculated the cumulative percentage of germination for 7 days. In both trials after 42 days in seeds and seedlings 52 days in length was measured and stem diameter, leaf number, dry weight of aerial parts, number of nodules/plant and percentage of nitrogen. All treatments stimulated germination, growth and BNF, being better in the native strains at a concentration of 108 cells/mL, compared with the commercial strain and the control. These results indicate the positive effect exerted by Rhizobium sp., in promoting growth and BNF, which could be used for further studies to establish the production of a biofertilizer, allowing potentiate the production of crops by gliricidia for food arich cattle as source of protein in the Caribbean Biotechnology Center.

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

    International Nuclear Information System (INIS)

    Bio fertilization technology was applied for improving canola plant growth and nutrient acquisition in sandy saline soil ,as a biological mean used to develop plant growth and nutrient uptake under salinity stress. Canola was cultivated in pots packed at rate of 7 kg saline sandy soil pot-1, and inoculated with Rhizobium leguminosarum biovar viceae, Azospirillum brasilense strain no. 40 and arbuscular mycorrhizal fungi either solely or in combinations of them. Nitrogen fertilizer was added in form (15NH4)2SO4 with 5%15N atom excess at rate of 0.99 g N pot-1. Maximum dry matter accumulation induced by composite inoculation (Rh + Azo + AM). Na concentrations were frequently affected by Rhizobium and /or mycorrhizae while K was affected by Azospirillum and /or mycorrhizae. Azospirillum enhanced Ca uptake whereas Mg content was responded well to composite inoculants of Rh + Azo + AM. Dual inoculation with Rh + Azo resulted in the highest values of N uptake by plant. Similar effect was noticed with P uptake when dual inoculums of Azo + AM were applied. Data of 15N isotope showed that the highest portion and value of N2-fixed was recorded with composite inoculums followed by dual inoculations. On the other hand, the infection with AM fungi gave the highest proportion of N derived from fertilizer as compared to other inoculants or uninoculated control. In the same trend, the fertilizer use efficiency (FUE%) was enhanced by AM infection. Dual inoculums of Rh + Azo induced highest content of proline in leaves. (Authors)

  15. Identification and characterization of the Rhizobium sp. strain GIN611 glycoside oxidoreductase resulting in the deglycosylation of ginsenosides.

    Science.gov (United States)

    Kim, Eun-Mi; Kim, Juhan; Seo, Joo-Hyun; Park, Jun-Seong; Kim, Duck-Hee; Kim, Byung-Gee

    2012-01-01

    Using enrichment culture, Rhizobium sp. strain GIN611 was isolated as having activity for deglycosylation of a ginsenoside, compound K (CK). The purified heterodimeric protein complex from Rhizobium sp. GIN611 consisted of two subunits with molecular masses of 63.5 kDa and 17.5 kDa. In the genome, the coding sequence for the small subunit was located right after the sequence for the large subunit, with one nucleotide overlapping. The large subunit showed CK oxidation activity, and the deglycosylation of compound K was performed via oxidation of ginsenoside glucose by glycoside oxidoreductase. Coexpression of the small subunit helped soluble expression of the large subunit in recombinant Escherichia coli. The purified large subunit also showed oxidation activity against other ginsenoside compounds, such as Rb1, Rb2, Rb3, Rc, F2, CK, Rh2, Re, F1, and the isoflavone daidzin, but at a much lower rate. When oxidized CK was extracted and incubated in phosphate buffer with or without enzyme, (S)-protopanaxadiol [PPD(S)] was detected in both cases, which suggests that deglycosylation of oxidized glucose is spontaneous. PMID:22020506

  16. Is 'Final' Really Final?

    OpenAIRE

    Tai, B

    2002-01-01

    Recently, the Appeal Committee of the Hong Kong Court of Final Appeal raised the question of whether that court had the power to hear an appeal against a decision of the Court of Appeal. The decision in question concerned a judgment of professional misconduct against an accountant by a disciplinary committee under the Professional Accountants Ordinance. The ordinance clearly states that the decision of the Court of Appeal is final. This article examines whether the Court of Final Appeal has t...

  17. Le Rouge et le Noir

    Directory of Open Access Journals (Sweden)

    Jean Pouillon

    2012-12-01

    Full Text Available Le due riletture proposte – la durissima recensione dedicata da Pouillon al Le Rouge et le Noir di Autant-Lara (1954, e una doppia intervista che attesta la proficua collaborazione di Chiara e Lattuada per la realizzazione di Venga a prendere il caffè da noi (1970 – mettono in gioco, in modi evidentemente diversissimi, problemi ricorrenti dell’adattamento come il peso del finale o le potenzialità (e le trappole del trasferimento dalla parola all’immagine. 

  18. Intensity of Ground Cover Crop Arachis pintoi, Rhizobium Inoculation and Phosphorus Application and Their Effects on Field Growth and Nutrient Status of Cocoa Plants

    Directory of Open Access Journals (Sweden)

    John Bako Baon

    2006-08-01

    Full Text Available Arachis pintoiis potentially as a cover crop for cocoa (Theobroma cacaoL. farm, however information regarding its effect on the growth of cocoa plants in the field is very limited. The objective of this experiment is to investigate the combined influence of ground cover crop A. pintoi, rhizobial bacterial inoculation and phosphorus (P fertilizer on the growth of cocoa in the field and nutrient status. This experiment laid out in split-split plot design consisted of three levels of cover crop (without, A. pintoiand Calopogonium caeruleum, two levels of rhizobium inoculation (not inoculated and inoculated and two levels of phosphorus application (no P added and P added. The results showed that in field condition the presence of A. pintoias cover crop did not affect the growth of cocoa. On the other hand, C. caeruleumas cover crop tended to restrict cocoa growth compared to A. pintoi. Application of P increased leaf number of cocoa plant. Biomass production of A. pintoiwas 40% higher than C. caeruleum. Soil organic carbon and nitrogen contents were not affected by ground cover crops, though higher value (0.235% N and 1.63% organic C was obtained from combined treatments of inoculation and P addition or neither inoculation nor P addition. In the case of no rhizobium inoculation, soil N content in cocoa farm with A. pintoicover crop was lower than that of without cover crop or with C. caeruleum. Cover crop increased plant N content when there was no inoculation, on the other hand rhizobium inoculation decreased N content of cocoa tissue. Tissue P content of cocoa plant was not influenced by A. Pintoicover crop or by rhizobium inoculation, except that the P tissue content of cocoa was 28% higher when the cover crop was C. caeruleumand inoculated. Key words : Arachis pintoi, Theobroma cacao, Calopogonium caeruleum, rhizobium, nitrogen, phosphorus.

  19. Agrice et les tensioactifs

    OpenAIRE

    Rocher Magali

    2001-01-01

    Agrice, Agriculture pour la chimie et l’énergie, est un groupement d’intérêt scientifique qui a pour objet l’animation, le financement, le suivi et l’évaluation de programmes de recherche et développement portant sur les nouvelles valorisations des produits et coproduits d’origine agricole dans les domaines de l’énergie, de la chimie et des matériaux. Aujourd’hui les programmes de recherche et développement sur les tensioactifs sont renforcés, plus sélectifs et plus directement tournés vers l...

  20. Cléopâtre et son goûteur

    OpenAIRE

    Mangematin, Vincent

    2003-01-01

    De William Shakespeare (Hamlet) à Victor Hugo (Lucrèce Borgia), en passant par Tristant et Iseult, Albert Goscinny et René Uderzo (Astérix et Cléopâtre) ou par P. Balland (Une affaire de goût, 2000, Julliard : Paris), la boisson et l'alimentation sont au coeur des controverses mettant en scène négligences, fraudes, trahisons, empoisonnements volontaires et dispositifs permettant de garantir le caractère non toxique des aliments. Se noue ainsi autour de l'alimentation un jeu complexe mêlant co...

  1. Respuesta de combinaciones Rhizobium - Clitoria ternatea en condiciones de estrés salino en el Valle del Cauto en Cuba / Response of Rhizobium - Clitoria ternatea combinations under salt stress in the Cauto Valley in Cuba

    Scientific Electronic Library Online (English)

    Raúl Carlos, López Sánchez; Roeland, Samson; Patrick, Vandamme; Bettina, Eichler-Löbermann; Ernesto, Gómez Padilla.

    2011-06-01

    Full Text Available Se estudió la respuesta de Clitoria ternatea en condiciones de estrés salino a la inoculación con aislamientos nativos y cepas comerciales de rizobios. El estudio se realizó en condiciones de invernadero y de campo. El efecto de tres cepas de rizobio (Jd19, 1031 y 1032) en el rendimiento y parámetro [...] s de la fijación de nitrógeno se comparó con el testigo y el tratamiento con fertilización nitrogenada. En el experimento en invernadero los mejores resultados para el rendimiento y parámetros de fijación de nitrógeno se encuentran con el aislamiento nativo de rizobio Jd19. En este tratamiento se encontraron los valores más altos de peso seco de masa aérea y raíces y de acumulación de nitrógeno. Además en el tratamiento con el aislamiento Jd19 se mostraron los valores más altos de relación K:Na, contenido de ureidos, clorofila a y b en el tallo y el mejor índice de efectividad de la inoculación. En el experimento de campo el tratamiento con el aislamiento Jd19 tuvo el mejor efecto positivo en comparación con el resto de los tratamientos. Los resultados indican que la combinación Clitoria ternatea-Jd19 es más eficiente en condiciones de estrés salino, y es posible su introducción a amplia escala en suelos afectados por la salinidad. Abstract in english The purpose of the present study was to examine response of Clitoria tarnatea under salt stress to inoculation with native isolates and commercial strains of Rhizobium. This study was carried out both in greenhouse and field conditions. Effects of three Rhizobium strains (Jd19, 1031 and 1032) were c [...] ompared to control and mineral N fertilization regarding yield and nitrogen fixation parameters. In the greenhouse experiment the best results for yield and nitrogen fixation parameters were found for the Jd19 native isolate treatment, where the highest dry weight of both shoots and roots and also of nitrogen uptake were observed. Besides, this treatment showed the highest K:Na ratio, as well as of contents of ureides, of a and b chlorophyll in stem and the best inoculation effectiveness index. In the field test, the Jd19 treatment showed the best positive effect in comparison to the other treatments. Results indicate that the Clitoria ternatea-Jd19 Rhizobium strain combination is the most efficient under salt stress and also that its wide scale introduction in saline soils is possible.

  2. Molecular and culture dependent characterization of endolithic bacteria in two beach sand samples and description of Rhizobium endolithicum sp. nov.

    Science.gov (United States)

    Parag, B; Sasikala, Ch; Ramana, Ch V

    2013-12-01

    Endolithic metagenome analysis of two beach samples collected form Chilika, Odisha, India indicated rich bacterial diversity. While the metagenome analysis of sample one yielded 16S rRNA gene sequences which represent six phyla and 16 genera, sample two yielded very rich diversity representing 17 phyla and 286 genera. Six species of bacteria were isolated from the endolithic enrichments and most of them have 16S rRNA gene sequence similarity of >99 % with known taxa, except for strain JC140(T) having Rhizobium yanglingense SH22623(T) (96.8 %), R. alkalisoli CCBAU 01393(T) (96.3 %), R. vignae CCBAU 05176(T) (96.2 %), R. mesosinicum CCBAU 25010(T) (96.1 %) and other members of the genus Rhizobium with characterized based on polyphasic taxonomic analysis. Strain JC140(T) could tolerate up to 5 % salinity, resistant to rifampicin (10 ?g) and was positive for catalase and oxidase. The major fatty acid is summed feature 8 (C18:1?7c/C18:1?6c) with minor amounts of C19:0 cyclo?8c, C16:0, C18:0, C17:0cyclo, summed feature 2 (C14:03OH/C16:1 isoI), summed feature 3 (C16:1?7c/C16:1?6c) and 2-hydroxyacid of C15:0. Diphosphatidylglycerol, phosphatidylethanol-amine, phosphatidylcholine, phosphatidylglycerol, unidentified lipids (L1, 2), unidentified phospholipid (PL1-4) constitute the polar lipids of strain JC140(T). The strain has bacteriohopane derivative (BHD2), diplopterol and two unidentified hopanes (UH1, 2) as major hopanoids. Q-10 is the major quinone of strain JC140(T). Based on polyphasic taxonomic analysis, strain JC140(T) represents a species in the genus Rhizobium for which, the name R. endolithicum sp. nov. is proposed. The type strain is JC140(T) (= KCTC32077(T) = CCUG64352(T) = MTCC11723(T) = HAMBI 2447(T)). PMID:24104485

  3. Propriedades reológicas e efeito da adição de sal na viscosidade de exopolissacarídeos produzidos por bactérias do gênero Rhizobium Rheological properties and effect of the salt addition on the exopolysaccharides viscosity produced by bacteria of Rhizobium genus

    Directory of Open Access Journals (Sweden)

    Gabriel Aranda-Selverio

    2010-01-01

    Full Text Available Viscosity of some polysaccharide solutions supports that these molecules can be applied in food sectors. Four exopolysaccharides (R1, R2, R3, R4 produced by different Rhizobium strains were selected. Sugar composition and differences in the uronic acid contents suggests that chemical structure of these molecules can vary when different culture conditions and strains are analyzed. The Power Law was the rheological model used to represent the experimental data of shear stress versus shear rate. All exopolysaccharides showed non-Newtonian behavior, with pseudoplastic characteristics. R1, R2 and R4 showed a slight increase in viscosity in the presence of 0,2 M NaCl.

  4. Propriedades reológicas e efeito da adição de sal na viscosidade de exopolissacarídeos produzidos por bactérias do gênero Rhizobium / Rheological properties and effect of the salt addition on the exopolysaccharides viscosity produced by bacteria of Rhizobium genus

    Scientific Electronic Library Online (English)

    Gabriel, Aranda-Selverio; Ana Lúcia Barretto, Penna; Luciana Frizarin, Campos-Sás; Osvaldo dos, Santos Junior; Ana Flora Dalberto, Vasconcelos; Maria de Lourdes Corradi da, Silva; Eliana Gertrudes Macedo, Lemos; João Carlos, Campanharo; Joana Léa Meira, Silveira.

    Full Text Available [...] Abstract in english Viscosity of some polysaccharide solutions supports that these molecules can be applied in food sectors. Four exopolysaccharides (R1, R2, R3, R4) produced by different Rhizobium strains were selected. Sugar composition and differences in the uronic acid contents suggests that chemical structure of t [...] hese molecules can vary when different culture conditions and strains are analyzed. The Power Law was the rheological model used to represent the experimental data of shear stress versus shear rate. All exopolysaccharides showed non-Newtonian behavior, with pseudoplastic characteristics. R1, R2 and R4 showed a slight increase in viscosity in the presence of 0,2 M NaCl.

  5. AVALIAÇÃO DA FIXAÇÃO BIOLÓGICA DO NITROGÊNIO EM GENÓTIPOS DE FEIJOEIROS TOLERANTES A SECA EVALUATION OF BIOLOGICAL FIXATION OF NITROGEN IN RHIZOBIUM UNDER WATER DEFICIT

    Directory of Open Access Journals (Sweden)

    Willian Bucker Moraes

    2010-04-01

    Full Text Available Vários fatores como a temperatura, acidez do solo, teor de nutrientes e cultivar, interferem na eficiência simbiótica das estirpes de Rhizobium em condições de campo. Com objetivo de avaliar a capacidade de fixação biológica de nitrogênio de estirpes nativas de Rhizobium sp. foi realizado um experimento em vasos montado no delineamento inteiramente casualizado no esquema fatorial 10x7 (10 linhagens de feijoeiro consideradas tolerantes ao déficit hídrico, sendo estas: Amarelinho, Macuquinho, Imperial, EL 22, BATT 477, Uirapuru, IAPAR-81, Bate Estrada, Serrano e Preto Meia Lua e 7 inoculantes isolados dos solos dos municipios de Colatina, Vila Pavão, Nova Venécia, Pinheiros, Sooretama, Linhares e Alegre, no estado do Espírito Santo, com quatro repetições. Os dados demonstraram que a fixação biológica de N2 utilizando a inoculação de estirpes eficientes de Rhizobium em cultivar nodulante de feijoeiro ou seu cultivo em solos com população nativa eficiente, pode possibilitar a suplementação ou até mesmo á não utilização de nitrogênio em cobertura na cultura do feijoeiro, sem perdas no rendimento da produtividade.Several factors as the temperature, soil acidity, content of nutrients and cultivate interfere in the symbiotic efficiency of the ancestries of Rhizobium infield conditions. With the objective of evaluating the capacity of biological fixation of nitrogen of native ancestries of Rhizobium sp. an experiment was accomplished in vases set up in the delineate entirely casualty in the factorial outline 10x7 (10 bean plant lineages considered tolerant to the water deficit, being these: Amarelinho, Macuquinho, Imperial, EL 22, BATT 477, Uirapuru, IAPAR-81, Bate Estrada, Serrano and Preto Meia Lua and 7 isolated inoculate of the soils of the municipal districts of Colatina, Vila Pavão, Nova Venécia, Pinheiros, Sooretama, Linhares and Alegre in Espírito Saint state, with four repetitions. The data demonstrated that the biological fixation of N2 using the inoculation of efficient ancestries of Rhizobium in cultivating bean plant nodule cultivation in soils with efficient native population, it can make possible the supplement or even to the not use of nitrogen in covering in the culture bean plant, without losses in the income of the productivity.

  6. Un nouvel habitat du Bronze final IIIb dans le Val d’Orléans et ses traces de métallurgie du fer : Bonnée, Les Terres à l’Est du Bourg (Centre, Loiret A new settlement from late Bronze IIIb in the val d’Orléans: Bonnée, Les Terres à l’Est du Bourg (lands to the east of the town (Centre, Loiret

    Directory of Open Access Journals (Sweden)

    Stéphane Joly

    2011-12-01

    Full Text Available La multiplication récente des diagnostics archéologiques autour du petit bourg actuel de Bonnée a permis la détection d’une occupation du Bronze final IIIb (circa 900-750 av. n.-e. sur environ un hectare aux Terres à l’Est du Bourg. Les limites inhérentes à ce type d’intervention réduisent l’interprétation des structures et toute approche spatiale de ce probable habitat repéré. L’étude conjointe des différents mobiliers en particulier céramique et métallurgique, mais aussi le torchis et la faune, atteste de sa culture matérielle et de son intérêt. Ces scories pourraient être parmi les plus anciennes traces en région Centre d’activité métallurgique du fer. Des activités de post-réduction sont avérées et certaines opérations de forgeage sont supposées.La découverte de cet habitat dans ce secteur du lit majeur de la Loire, apporte de nouvelles données concernant l’occupation du sol et ses problématiques évolutives dans le Val d’Orléans sur ces périodes de transition avec le Hallstatt ancien.The recent increase in the archaeological evaluations around the village of Bonnée has enabled the discovery of a final Bronze Age IIIb settlement (circa 900-750 BP on about a hectare of the Terres à l’Est du Bourg. The limits inherent in this type of work restrict the interpretation of structures and all spatial approaches to this likely dwelling. The joint study of the different furnishings, in particular ceramics and metal, but also the cob and fauna, attests to its material culture and its interest. The slag could be amongst the oldest iron metallurgy remains from the Centre region. Some activities of post-forging are proven and certain operations are guessed at. The discovery of this settlement in this sector of the major bed of the Loire, has produced new data concerning the occupation of the land and its evolutionary problems in the valley of Orleans over these periods of transition in the early Hallstatt.

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

    Directory of Open Access Journals (Sweden)

    V Bianciotto

    2009-12-01

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

  8. Response of lupine plants irrigated with saline water to rhizobium inoculation using 15N-isotope dilution

    International Nuclear Information System (INIS)

    The lupine Rhizobium symbiosis and contribution of N2 fixation under different levels of irrigation water salinity were examined. Lysimeter experiment was established under greenhouse conditions during the year 2002-2003. In this experiment, inoculated plants were imposed to different salinity levels of irrigation water and N-fertilizer treatment. Plant height was decreased under different salinity levels, nitrogen treatments and bacterial inoculation. Similar trend was noticed with leaf area. The highest leaf area was recorded with salt tolerant bacterial inoculation (SBI) and splitting N-treatment. Highest values of N-uptake occurred after 100 day intervals under the tested factors. Relative decrease in N-uptake did not exceed 40% of those recorded with the fresh water treatment as affected by experimental factors. Nitrogen uptake by the whole plant reflected an increase at 3 dS/m salinity level of irrigation water. Relative increases were 5% and 15% for normal bacteria inoculation under single dose (NI) and splitting

  9. Mechanisms of protection of pea plants by polysaccharides extracted from a strain of Rhizobium against Orobanche crenata

    International Nuclear Information System (INIS)

    The Broomrape causes notable damage on the leguminous crops and became major factor limiting production of pea in the Mediterranean region. The effect of the polysaccharides extracted from P.SOM Rhizobium strain on the development of Orobanche crenata on pea was studied. The results showed that the lipopolysaccharides significantly reduce the infestation of pea by O. crenata. This limitation of infestation results from the reduction of seeds germination rates of the parasite resulting in reduction of the tubercles number on pea roots. Moreover, necrosis of orobanche before or after attachment on pea roots treated by LPS can explain this reduction of parasitism. A correlation was observed between the reduction of pea infection by the broomrape and the activation phenolic compounds pathway. This activation resulted to increase of two enzymes (peroxidase and polyphenoloxidase) activities these enzymes are implicated in plant defense. The results of our study showed that the LPS seem implied in the induction of pea resistance against the broomrape.

  10. Multiplicity of Sulfate and Molybdate Transporters and Their Role in Nitrogen Fixation in Rhizobium leguminosarum bv. viciae Rlv3841.

    Science.gov (United States)

    Cheng, Guojun; Karunakaran, Ramakrishnan; East, Alison K; Poole, Philip S

    2016-02-01

    Rhizobium leguminosarum Rlv3841 contains at least three sulfate transporters, i.e., SulABCD, SulP1 and SulP2, and a single molybdate transporter, ModABC. SulABCD is a high-affinity transporter whose mutation prevented growth on a limiting sulfate concentration, while SulP1 and SulP2 appear to be low-affinity sulfate transporters. ModABC is the sole high-affinity molybdate transport system and is essential for growth with NO3(-) as a nitrogen source on limiting levels of molybdate (pea plants inoculated with LMB695 (modB) reduced acetylene at only 14% of the wild-type rate, and this was not further reduced in the quadruple mutant. Overall, while modB is crucial to nitrogen fixation at limiting molybdate levels in the presence of sulfate, there is an unidentified molybdate transporter also capable of sulfate transport. PMID:26812045

  11. Effect of Rhizobium and arbuscular mycorrhizal fungi inoculation on electrolyte leakage in Phaseolus vulgaris roots overexpressing RbohB.

    Science.gov (United States)

    Arthikala, Manoj-Kumar; Nava, Noreide; Quinto, Carmen

    2015-01-01

    Respiratory oxidative burst homolog (RBOH)-mediated reactive oxygen species (ROS) regulate a wide range of biological functions in plants. They play a critical role in the symbiosis between legumes and nitrogen-fixing bacteria or arbuscular mycorrhizal (AM) fungi. For instance, overexpression of PvRbohB enhances nodule numbers, but reduces mycorrhizal colonization in Phaseolus vulgaris hairy roots and downregulation has the opposite effect. In the present study, we assessed the effect of both rhizobia and AM fungi on electrolyte leakage in transgenic P. vulgaris roots overexpressing (OE) PvRbohB. We demonstrate that elevated levels of electrolyte leakage in uninoculated PvRbohB-OE transgenic roots were alleviated by either Rhizobium or AM fungi symbiosis, with the latter interaction having the greater effect. These results suggest that symbiont colonization reduces ROS elevated electrolyte leakage in P. vulgaris root cells. PMID:25946118

  12. Crystallization and preliminary X-ray diffraction studies of maleylacetate reductase from Rhizobium sp. strain MTP-10005

    International Nuclear Information System (INIS)

    Maleylacetate reductase from Rhizobium sp. strain MTP-10005 has been crystallized using the sitting-drop vapour-diffusion method and microseeding. The crystals contained one dimeric molecule per asymmetric unit and diffracted to 1.79 Å resolution. Maleylacetate reductase (EC 1.3.1.32), which catalyzes the reduction of maleylacetate to 3-oxoadipate, plays an important role in the aerobic microbial catabolism of resorcinol. The enzyme has been crystallized at 293 K by the sitting-drop vapour-diffusion method supplemented with a microseeding technique, using ammonium sulfate as the precipitating agent. The crystal belonged to the monoclinic space group C2, with unit-cell parameters a = 56.85, b = 121.13, c = 94.09 Å, ? = 101.48°, and contained one dimeric molecule in the asymmetric unit. It diffracted to 1.79 Å resolution

  13. A Rhizobium radiobacter Histidine Kinase Can Employ Both Boolean AND and OR Logic Gates to Initiate Pathogenesis.

    Science.gov (United States)

    Fang, Fang; Lin, Yi-Han; Pierce, B Daniel; Lynn, David G

    2015-10-12

    The molecular logic gates that regulate gene circuits are necessarily intricate and highly regulated, particularly in the critical commitments necessary for pathogenesis. We now report simple AND and OR logic gates to be accessible within a single protein receptor. Pathogenesis by the bacterium Rhizobium radiobacter is mediated by a single histidine kinase, VirA, which processes multiple small molecule host signals (phenol and sugar). Mutagenesis analyses converged on a single signal integration node, and finer functional analyses revealed that a single residue could switch VirA from a functional AND logic gate to an OR gate where each of two signals activate independently. Host range preferences among natural strains of R. radiobacter correlate with these gate logic strategies. Although the precise mechanism for the signal integration node requires further analyses, long-range signal transmission through this histidine kinase can now be exploited for synthetic signaling circuits. PMID:26310519

  14. Fluorescence studies with malate dehydrogenase from rhizobium japonicum 3I1B-143 bacteroids: a two-tryptophan containing protein

    Science.gov (United States)

    Ghiron, Camillo A.; Eftink, Maurice R.; Waters, James K.; Emerich, David W.

    1990-05-01

    A number of fluorescence studies, both of trp residues and bound NADH, have been reported for porcine MDH. The large number of trp residues (6) complicates the interpretation of some studies. To circumvent this we have performed studies with a two tryptophan (per subunit) MDH from Rhizobium japonicum 311B-143 bacteroids. We have performed phase/modulation fluorescence lifetime measurements, as a function of temperature and added quencher KI, in order to resolved the 1.3 ns (blue) and 6.6 ns (red) contributions from the two classes of trp residues. Anisotropy decay studies have also been performed. The binding of NADH dynamically quenches the fluorescence of both tip residues, but, unlike mammalian cytoplasmic and mitochondrial MDH, there is not a large enhancement in fluorescence of bound NADH upon forming a ternary complex with either tartronic acid or D-malonate.

  15. Comparison of the nitrogen-15 and conventional methods to determine N2 fixing capacity of chickpea by rhizobium strains

    International Nuclear Information System (INIS)

    The N2 fixing capacity of 8 strains of rhizobium ciceri (45, 68, 51,620, 29,18,23 and 31) in association with two cicer cultivars (Akcin-91 and Izmir-92) was evaluated under growth room conditions as a preliminary screening prior to field experimentation. The ''1''5N isotope method (A-value) was used to quantify the % Ndfa and actual amounts of N2 fixed. In addition to this, other conventional methods (dry matter, N content, total N uptake, difference method and symbiotic effectiveness) were also investigated in the comparison. The results obtained show that 18 and 31 number of strains could be successfully used as inoculant both cultivar

  16. In vitro Survival and Nematicidal Activity of Rhizobium, Bradyrhizobium and Sinorhizobium. I. The Influence of Various NaCl Concentrations

    Directory of Open Access Journals (Sweden)

    S. Shahid Shaukat

    2002-01-01

    Full Text Available During the survey of the cultivated fields in Karachi and neighborhood (Southern Sindh, 3 strains of Rhizobium phaseoli, 1 strain of R. leguminosarum and R. trifolii each, 5 strains of Sinorhizobium meliloti, 2 strains of Bradyrhizobium japonicum and 3 strains of Bradyrhizobium sp. were isolated and identified. The 15 strains of rhizobia tested for their growth under saline media exhibited varying degree of effects to salt concentrations. Most resistant strain was that of S. meliloti MAT1(R9 while least resistant was that of Bradyrhizobium sp. VRM1(R13. All the rhizobial strains caused significant mortality of Meloidogyne incognita, the root-knot nematode juveniles in vitro, though the strains differed markedly in their toxic activity. The rhizobial strains showed significant interaction with NaCl salinity towards M. incognita

  17. Crystallization and preliminary X-ray diffraction studies of maleylacetate reductase from Rhizobium sp. strain MTP-10005

    Energy Technology Data Exchange (ETDEWEB)

    Fujii, Tomomi; Goda, Yuko [Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011 (Japan); Yoshida, Masahiro; Oikawa, Tadao [Department of Life Science and Biotechnology, Faculty of Chemistry, Materials and Bioengineering, Kansai University, Suita, Osaka 564-8680 (Japan); Hata, Yasuo, E-mail: hata@scl.kyoto-u.ac.jp [Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011 (Japan)

    2008-08-01

    Maleylacetate reductase from Rhizobium sp. strain MTP-10005 has been crystallized using the sitting-drop vapour-diffusion method and microseeding. The crystals contained one dimeric molecule per asymmetric unit and diffracted to 1.79 Å resolution. Maleylacetate reductase (EC 1.3.1.32), which catalyzes the reduction of maleylacetate to 3-oxoadipate, plays an important role in the aerobic microbial catabolism of resorcinol. The enzyme has been crystallized at 293 K by the sitting-drop vapour-diffusion method supplemented with a microseeding technique, using ammonium sulfate as the precipitating agent. The crystal belonged to the monoclinic space group C2, with unit-cell parameters a = 56.85, b = 121.13, c = 94.09 Å, ? = 101.48°, and contained one dimeric molecule in the asymmetric unit. It diffracted to 1.79 Å resolution.

  18. Facteurs environnementaux et psychologiques et asthme infantile

    OpenAIRE

    Zhou, Cailiang,

    2014-01-01

    Les objectifs de cette thèse est d'examiner l'hypothèses selon laquelle les caractéristiques psychologiques constituent modificateur de la relation entre l'exposition aux polluants atmosphériques et l'asthme infantile. A cet effet, nous avons utilisé les données de l'Etude des 6 villes avec dessein transversale, et l'étude de cohorte mère-enfant de type longitudinale EDEN (Étude sur les Déterminants pré et postnatalsdu développement de la santé l'ENfant) pour examiner cette hypothèse.Les donn...

  19. Energie et développement

    Directory of Open Access Journals (Sweden)

    Gilles Carbonnier

    2011-05-01

    Full Text Available Cet article introduit le dossier thématique consacré à la relation intime entre énergie et développement. Les auteurs retracent l’importance des énergies fossiles dans la croissance économique du monde occidental dès le XIXe siècle et le rôle central du pétrole au XXe siècle pour s’interroger sur les limites de ce modèle de développement face aux contraintes géologiques et climatiques. Ils examinent le fossé et les malentendus qui séparent les sciences de l’homme  et les sciences de la nature, ainsi que les récentes initiatives de dialogue interdisciplinaire autour de l’économie écologique et de l’écologie industrielle. Ils analysent ensuite les enjeux spécifiques aux pays en développement ainsi que l’inadéquation du système de gouvernance internationale pour faire face aux tensions croissantes liées à la déplétion du pétrole, aux asymétries d’accès et d’exploitation des ressources minérales et aux conséquences environnementales d’une consommation croissante de ressources non renouvelables.

  20. Nickel detoxification and plant growth promotion by multi metal resistant plant growth promoting Rhizobium species RL9.

    Science.gov (United States)

    Wani, Parvaze Ahmad; Khan, Mohammad Saghir

    2013-07-01

    Pollution of the biosphere by heavy metals is a global threat that has accelerated dramatically since the beginning of industrial revolution. The aim of the study is to check the resistance of RL9 towards the metals and to observe the effect of Rhizobium species on growth, pigment content, protein and nickel uptake by lentil in the presence and absence of nickel. The multi metal tolerant and plant growth promoting Rhizobium strain RL9 was isolated from the nodules of lentil. The strain not only tolerated nickel but was also tolerant o cadmium, chromium, nickel, lead, zinc and copper. The strain tolerated nickel 500 ?g/mL, cadmium 300 ?g/mL, chromium 400 ?g/mL, lead 1,400 ?g/mL, zinc 1,000 ?g/mL and copper 300 ?g/mL, produced good amount of indole acetic acid and was also positive for siderophore, hydrogen cyanide and ammonia. The strain RL9 was further assessed with increasing concentrations of nickel when lentil was used as a test crop. The strain RL9 significantly increased growth, nodulation, chlorophyll, leghaemoglobin, nitrogen content, seed protein and seed yield compared to plants grown in the absence of bioinoculant but amended with nickel The strain RL9 decreased uptake of nickel in lentil compared to plants grown in the absence of bio-inoculant. Due to these intrinsic abilities strain RL9 could be utilized for growth promotion as well as for the remediation of nickel in nickel contaminated soil. PMID:23609454

  1. Thermophilic, reversible gamma-resorcylate decarboxylase from Rhizobium sp. strain MTP-10005: purification, molecular characterization, and expression.

    Science.gov (United States)

    Yoshida, Masahiro; Fukuhara, Nobuhiro; Oikawa, Tadao

    2004-10-01

    We found the occurrence of thermophilic reversible gamma-resorcylate decarboxylase (gamma-RDC) in the cell extract of a bacterium isolated from natural water, Rhizobium sp. strain MTP-10005, and purified the enzyme to homogeneity. The molecular mass of the enzyme was determined to be about 151 kDa by gel filtration, and that of the subunit was 37.5 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis; in other words, the enzyme was a homotetramer. The enzyme was induced specifically by the addition of gamma-resorcylate to the medium. The enzyme required no coenzyme and did not act on 2,4-dihydroxybenzoate, 2,5-dihydroxybenzoate, 3,4-dihydroxybenzoate, 3,5-dihydroxybenzoate, 2-hydroxybenzoate, or 3-hydroxybenzoate. It was relatively thermostable to heat treatment, and its half-life at 50 degrees C was estimated to be 122 min; furthermore, it catalyzed the reverse carboxylation of resorcinol. The values of k(cat)/K(m) (mMu(-1) . s(-1)) for gamma-resorcylate and resorcinol at 30 degrees C and pH 7 were 13.4 and 0.098, respectively. The enzyme contains 327 amino acid residues, and sequence identities were found with those of hypothetical protein AGR C 4595p from Agrobacterium tumefaciens strain C58 (96% identity), 5-carboxyvanillate decarboxylase from Sphingomonas paucimobilis (32%), and 2-amino-3-carboxymuconate-6-semialdehyde decarboxylases from Bacillus cereus ATCC 10987 (26%), Rattus norvegicus (26%), and Homo sapiens (25%). The genes (graA [1,230 bp], graB [888 bp], and graC [1,056 bp]) that are homologous to those in the resorcinol pathway also exist upstream and downstream of the gamma-RDC gene. Judging from these results, the resorcinol pathway also exists in Rhizobium sp. strain MTP-10005, and gamma-RDC probably catalyzes a reaction just before the hydroxylase in it does. PMID:15466039

  2. Impact of dual inoculation with Rhizobium and PGPR on growth and antioxidant status of Vicia faba L. under copper stress.

    Science.gov (United States)

    Fatnassi, Imen Challougui; Chiboub, Manel; Saadani, Omar; Jebara, Moez; Jebara, Salwa Harzalli

    2015-04-01

    Plant-growth-promoting bacteria (PGPR) may help reduce the toxicity of heavy metals in plants in polluted environments. In this work, the effects of dual inoculation with Rhizobium and PGPR strains on the growth of Vicia faba grown under copper stress were assessed during hydroponic culture. Growth parameters, copper (Cu) accumulation and antioxidant enzyme activities were studied. Copper concentrations above 1mM damaged plant growth, but co-inoculation reduced its harmful effect. Co-inoculation of plants treated with 1mM Cu and 2mM Cu increased the dry weights as compared with Cu-treated and uninoculated plants. However, it decreased copper uptake up to 80% in the roots of 1-mM-Cu-treated plants as compared to non-inoculated control. Copper tolerance in Vicia faba is linked to the activity of antioxidant systems that are modulated by metal concentrations: both superoxide dismutase (SOD) and catalase (CAT) were higher in the presence of Cu; a lower Cu dose of 0.5mM stimulated ascorbate peroxidase (APX) and/or peroxidase (POX) activities in shoots and roots; however in nodules CAT appeared to be the main peroxidase in H2O2 scavenging. The 1mM Cu treatment enhanced SOD, CAT and APX activities in roots and only SOD and POX were activated in shoots. All enzyme activities were inhibited by inoculation of 2mM Cu. The effect of inoculation with copper-accumulating PGPRs and the status of the antioxidant enzyme system were linked to changes in the copper tolerance status of Vicia faba. Our results suggested that Vicia faba inoculation with Rhizobium and PGPR Enterobacter clocae and Pseudomonas sp. could help to alleviate copper stress under hydroponic conditions. This result should be tested under field conditions for soil fertilization and phytostabilisation purposes. PMID:25747267

  3. Etique et gerance

    OpenAIRE

    Kliksberg, Bernardo

    2011-01-01

    L'auteur analyse le « vide éthique » dans lequel se trouvent plusieurs sociétés latinoaméricaines, la relation entre l'éthique et le leadership directif, et la conception des politiques économiques et sociales dans l'affectation des ressources des organisations.

  4. Et redskab i formskaben

    DEFF Research Database (Denmark)

    Thomsen, Bente Dahl

    Et innovativt didaktisk projekt, der arbejder med at udvikle et redskab til brug ved undervisningen i formskaben underlagt et universitært system. Det betyder at tidligere praksisbaseret læring i værksteder er omlagt til forskningsbaseret undervisning i auditoriumlignende lokaler. Projektet hvile...

  5. Fiction, existence et référence

    Directory of Open Access Journals (Sweden)

    Amie L. Thomasson

    2010-04-01

    Full Text Available L’article publié ici se propose d’emprunter une voie qui n’avait pas été empruntée dans les explorations précédentes de l’auteur. En effet, on verra qu’il s’agit ici de surmonter les difficultés auxquelles sont confrontées les théories réalistes de la fiction et en particulier la théorie artefactuelle dont Amie Thomasson est l’auteur.La question principale s’édicte en ces termes : s’il y a des personnages de fiction, comment se fait-il qu’il nous soit naturel de dire que tel ou tel personnage n’existe pas ?  Comment rendre compte des affirmations de non-existence des personnages de fiction, en particulier lorsqu’on est un réaliste de la fiction ?L’auteur confronte trois manières de traiter ces affirmations : l’approche par la quantification restreinte et l’approche linguistique et enfin l’approche des conditions d’application, point de vue auquel l’auteur se rallie. La première approche consiste à faire des restrictions spatiales ou catégorielles afin de cerner le champ de la référence. La seconde approche, qui est celle que les théoriciens de la référence directe emploient majoritairement, consiste à passer par le métalangage, c’est-à-dire de passer à un niveau sémantique supérieur. La dernière approche, celle par les conditions d’application, est construite sur les vertus des deux premières approches. Enfin, l’auteur élargira l’apport de cette dernière approche aux débats métaphysiques.The Amie Thomasson’s paper continues to explore the thesis she developed in Fiction and Metaphysics about the problems of reference. More precisely, the issues are about the problems that a realistic view of abstract objects can encounter. Here, the question has to be written in a particular way: if there are fictional characters, why do we quite naturally say that such or such character doesn’t exist? How can a realist overthrow such difficulties explaining the claims of non-existence can be true when we are for such a view?  The author presents three approaches of these claims: the restricted quantification approach, the metalinguistic approach and finally the application conditions approach. The first approach is about spatial and categorical restrictions in order to outline the field the reference is applied. The second approach is the way the direct reference theorists choose. The strategy consists in using the metalanguage that is to say to pass by a higher semantic level. The last approach which is the condition application approach is constructed with the virtues of the previous approaches. Finally, the author will show how the last view can be used for the metaphysics discussions.

  6. Final seminar of the 11A025 research project : Instrumentation and monitoring methods for civil engineering applications : Laboratoire Central des Ponts et Chaussées, Bouguenais, 14-15 décembre 2005

    OpenAIRE

    LABORATOIRE CENTRAL DES PONTS ET CHAUSSEES - LCPC

    2005-01-01

    Le contrôle de structure ainsi que les outils associés s'y rattachant prennent de plus en plus une solide et croissante importantce pour les utilisateurs des méthodes expérimentales dans le génie civil. Les systèmes de mesure servent non seulement dans le cadre du suivi de la pathologie d'un pont ou d'un comportement défectueux, mais également en tant que vrais systèmes automatisés de prise de décision ou d'outils pour le contrôle actif de structure. De nos jours, ces systèmes comportent les ...

  7. Réseaux et histoires

    Directory of Open Access Journals (Sweden)

    Harrison White

    2007-10-01

    Full Text Available Les réseaux sociaux ne sont pas constitués de « tuyaux » reliant des entités figées. Ils résultent des efforts de contrôle des identités pour faire face à l’incertitude radicale, aussi bien dans le monde social que dans le monde bio-physique. Ces efforts de contrôle produisent des histoires, dont dérivent les liens qui constituent les réseaux. Ainsi, une relation est interprétée à travers des histoires, non seulement par ceux qui y participent mais aussi par les observateurs. Les histoires s’enchevêtrent et forment des assemblages dans lesquels des régularités peuvent être observées, notamment trois façons de différencier les liens. La première façon consiste à spécifier un type de lien sur la base des formes de recouvrement observées entre des identités et des groupes. La deuxième façon distingue l’asymétrie et la symétrie dans les relations. Enfin, la troisième façon de différencier est fondée sur la force des liens. Les liens peuvent donc être de type multiplexe ou spécialisé, selon qu’ils associent différents registres ou non, les topologies de réseau pouvant être reconstruites à partir de ces différentes perspectives. Dans tous les cas, la notion de réseau qui émerge de cette approche est étroitement liée à de complexes formations narratives et peut servir aussi bien aux acteurs qu’aux observateurs pour rendre compte de la vie sociale.Networks and storiesSocial networks are not « pipes » connecting motionless entities. They are the result of control attempts by identities dealing with uncertainty, both in their social and bio-physical environments. These control attempts evoke stories from which links constituting networks are derived. A relation is thus interpreted through stories, not only by those who are embedded in them, but also by observers. Stories intermesh and yield assemblages in which regularities can be observed, notably three ways of distinguishing links. The first way is induced by overlaps among identities and groups. The second way is based on symmetry and asymmetry. Finally, the third way is related to the strength of ties. Therefore, links can be multiplex if they interlock different topics or specialized otherwise. Network topologies can be built on these different perspectives. In any case, the notion of network used in this approach is closely related to complex narratives and can be used by actors and observers alike to account for social life.Devenir histórico y redes socialesLos conjuntos sociales no están constituidos por « tubos » que unen entidades immobiles sinó que son el resultado del control ejercido por las diferentes identidades para afrontar la incertitud radical presente tanto en lo social como en el ámbito de lo biológico y de lo físico. Esta voluntad de control forja historias que originan conexiones que a su vez forman redes sociales. Por consiguiente, una relación es interpretada a través de esas historias, no solamente por los que participan en ellas sino también por los observadores. Las historias se mezclan entre ellas y acaban formando conjuntos con acontecimientos presentes cuya regularidad puede ser observada de tres maneras. La primera consiste en la especificación del tipo de conexión a partir de las formas que conforman las identidades y los grupos. La segunda consiste en distinguir la asimetría y la simetría de las relaciones. La tercera manera de diferenciar está asentada en la fuerza entre las diferentes conexiones. Las conexiones pueden ser de tipo complejo y múltiple o bien especializadas según que asocien diferentes ámbitos o no porque las topologías de las redes pueden ser reconstruidas a partir de esas diferentes perspectivas. En todos estos casos la noción de red  que emerge de esta aproximación está estrechamente ligada a complejos conjuntos narrativos y puede ser útil tanto para los participantes como para los observadores que describen y analizan las relaciones sociales.

  8. Cartographie et intelligence artificielle

    Directory of Open Access Journals (Sweden)

    Denise Pumain

    2005-11-01

    Full Text Available Le monde complexe dans lequel nous évoluons est aussi paradoxal : ainsi, que peut-on prédire quant à la diffusion du savoir faire des géographes en termes de cartographie et de visualisation de l’information géographique ? On voit surgir toujours plus d’instruments et d’occasions de se repérer et d’admirer des images de la terre, mais il n’est pas sûr que cela fasse progresser dans le public la connaissance des cartes et de leur interprétation. Prenons l’exemple du repérage, par GPS, et bient...

  9. Vin et Mondialisation : préface

    Directory of Open Access Journals (Sweden)

    Chantal Crenn

    2004-12-01

    Full Text Available L’actualité cinématographique de ces derniers mois avec la sortie de Mondovino et Sideways illustre un certain nombre de tensions qui s’attachent à la mondialisation du produit “vin” et au soi-disant clivage entre le Nouveau Monde et la Vieille Europe, la marque et le terroir, la modernité et la tradition, autant de concepts masquant la complexité de ce processus. Le terme de ‘mondialisation’, d’usage fort répandu dans les médias, mérite sans doute quelques précautions. L’usage courant renvoi...

  10. Sodium Dodecyl Sulfate-Polyacrylamide Gel Electrophoresis Protein Banding Patterns among Rhizobium leguminosarum biovar phaseoli Strains Isolated from the Mexican Bean Phaseolus coccineus

    OpenAIRE

    Arredondo-peter, R.; Escamilla, E

    1993-01-01

    Several rhizobial strains were isolated from Phaseolus coccineus root nodules and were determined to be Rhizobium leguminosarum biovar phaseoli strains after reinfection of the same host plant. These strains were characterized by cultural procedures (growth on different carbon sources and intrinsic antibiotic resistance) and electrophoretic procedures (sodium dodecyl sulfate-polyacrylamide gel electrophoresis of total proteins). Our results showed that these rhizobia are very similar to each ...

  11. Analysis of Poly-?-Hydroxybutyrate in Rhizobium japonicum Bacteroids by Ion-Exclusion High-Pressure Liquid Chromatography and UV Detection †

    OpenAIRE

    Karr, Dale B.; Waters, James K.; Emerich, David W.

    1983-01-01

    Ion-exclusion high-pressure liquid chromatography (HPLC) was used to measure poly-?-hydroxybutyrate (PHB) in Rhizobium japonicum bacteroids. The products in the acid digest of PHB-containing material were fractionated by HPLC on Aminex HPX-87H ion-exclusion resin for organic acid analysis. Crotonic acid formed from PHB during acid digestion was detected by its intense absorbance at 210 nm. The Aminex-HPLC method provides a rapid and simple chromatographic technique for routine analysis of org...

  12. Flavone-enhanced accumulation and symbiosis-related biological activity of a diglycosyl diacylglycerol membrane glycolipid from Rhizobium leguminosarum biovar trifolii.

    OpenAIRE

    Orgambide, G G; Philip-Hollingsworth, S; Hollingsworth, R I; Dazzo, F. B.

    1994-01-01

    Rhizobium leguminosarum bv. trifolii is the bacterial symbiont which induces nitrogen-fixing root nodules on the leguminous host, white clover (Trifolium repens L.). In this plant-microbe interaction, the host plant excretes a flavone, 4',7-dihydroxyflavone (DHF), which activates expression of modulation genes, enabling the bacterial symbiont to elicit various symbiosis-related morphological changes in its roots. We have investigated the accumulation of a diglycosyl diacylglycerol (BF-7) in w...

  13. Involvement of exo5 in Production of Surface Polysaccharides in Rhizobium leguminosarum and Its Role in Nodulation of Vicia sativa subsp. nigra

    OpenAIRE

    Laus, Marc C.; Logman, Trudy J.; van Brussel, Anton A. N.; Carlson, Russell W; Azadi, Parastoo; Gao, Mu-Yun; Kijne, Jan W

    2004-01-01

    Analysis of two exopolysaccharide-deficient mutants of Rhizobium leguminosarum, RBL5808 and RBL5812, revealed independent Tn5 transposon integrations in a single gene, designated exo5. As judged from structural and functional homology, this gene encodes a UDP-glucose dehydrogenase responsible for the oxidation of UDP-glucose to UDP-glucuronic acid. A mutation in exo5 affects all glucuronic acid-containing polysaccharides and, consequently, all galacturonic acid-containing polysaccharides. Exo...

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

    DEFF Research Database (Denmark)

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

    2009-01-01

    Endosymbiotic infection of legume plants by Rhizobium bacteria is initiated through infection threads (ITs) which are initiated within and penetrate from root hairs and deliver the endosymbionts into nodule cells. Despite recent progress in understanding the mutual recognition and early symbiotic signaling cascades in host legumes, the molecular mechanisms underlying bacterial infection processes and successive nodule organogenesis are still poorly understood. We isolated a novel symbiotic mutan...

  15. Growth, nodulation and yield of mash bean (Vigna mungo L.) as affected by Rhizobium inoculation and soil applied L-tryptophan

    OpenAIRE

    Muhammad Iqbal Hussain*, Muhammad Javed Akhtar, Hafiz Naeem Asghar and Maqshoof Ahmad

    2011-01-01

    Most of the grain legumes in Pakistan are poorly nodulated either because of low indigenous rhizobialpopulation or due to inefficient strains of native rhizobia. However, improvement in nodulation could be achievedthrough inoculation with effective rhizobial strains. A pot trial was conducted to evaluate the effect of Rhizobiuminoculation along with L-tryptophan (L-TRP), a precursor of indole acetic acid (IAA) on growth, yield andnodulation of mash been. The results indicated that Rhizobium i...

  16. Alfalfa yield response to inoculation with recombinant strains of Rhizobium meliloti with an extra copy of dctABD and/or modified nifA expression.

    OpenAIRE

    Bosworth, A H; M. K. Williams; Albrecht, K. A.; Kwiatkowski, R.; Beynon, J; Hankinson, T R; Ronson, C W; Cannon, F; Wacek, T. J.; Triplett, E W

    1994-01-01

    The construction of rhizobial strains which increase plant biomass under controlled conditions has been previously reported. However, there is no evidence that these newly constructed strains increase legume yield under agricultural conditions. This work tested the hypothesis that carefully manipulating expression of additional copies of nifA and dctABD in strains of Rhizobium meliloti would increase alfalfa yield in the field. The rationale for this hypothesis is based on the positive regula...

  17. The exopolysaccharide of Rhizobium sp. YAS34 is not necessary for biofilm formation on Arabidopsis thaliana and Brassica napus roots but contributes to root colonization

    OpenAIRE

    Santaella, Catherine; Schue, Mathieu; Berge, Odile; Heulin, Thierry; Achouak, Wafa

    2008-01-01

    Microbial exopolysaccharides (EPSs) play key roles in plant–microbe interactions, such as biofilm formation on plant roots and legume nodulation by rhizobia. Here, we focused on the function of an EPS produced by Rhizobium sp. YAS34 in the colonization and biofilm formation on non-legume plant roots (Arabidopsis thaliana and Brassica napus). Using random transposon mutagenesis, we isolated an EPS-deficient mutant of strain YAS34 impaired in a glycosyltransferase gene (gta). Wild type and muta...

  18. Complete genome sequence of Rhizobium leguminosarum bv trifolii strain WSM2304, an effective microsymbiont of the South American clover Trifolium polymorphum.

    OpenAIRE

    Reeve, Wayne; O’Hara, Graham; Chain, Patrick; Ardley, Julie; Bräu, Lambert; Nandesena, Kemanthi; Tiwari, Ravi; Malfatti, Stephanie; Kiss, Hajnalka; Lapidus, Alla; Copeland, Alex; Nolan, Matt; Land, Miriam; Ivanova, Natalia; Mavromatis, Konstantinos

    2010-01-01

    Rhizobium leguminosarum bv trifolii is the effective nitrogen fixing microsymbiont of a diverse range of annual and perennial Trifolium (clover) species. Strain WSM2304 is an aerobic, motile, non-spore forming, Gram-negative rod, isolated from Trifolium polymorphum in Uruguay in 1998. This microsymbiont predominated in the perennial grasslands of Glencoe Research Station, in Uruguay, to competitively nodulate its host, and fix atmospheric nitrogen. Here we describe the basic features of WSM23...

  19. Phenotypic variation and molecular signaling in the interaction of the rhizosphere bacteria Acidovorax sp. N35 and Rhizobium radiobacter F4 with roots

    OpenAIRE

    Li, Dan

    2011-01-01

    The aim of this doctoral thesis was to investigate the factors relevant in plant interaction of two plant growth promoting rhizobacteria (PGPR). For this, the strain Acidovorax sp. N35 isolated from surface sterilized wheat roots and the two strains F4 and F7 of Rhizobium radiobacter, a bacterium associated with the plant growth promoting fungus Piriformospora indica, were chosen. First of all, the isolate N35 was characterized using phylogenetic and taxonomic methods. The 16S rRNA gene seque...

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

    OpenAIRE

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

    2015-01-01

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

  1. Genetic analysis and phenotypic characterization of three novel genes of Rhizobium tropici CIAT899 involved in symbiotic interactions with Phaseolus vulgaris

    OpenAIRE

    Rojas Jimenez, Keilor

    2005-01-01

    Rhizobium tropici CIAT899 is highly tolerant to many environmental stresses and a good competitor for nodule occupancy of Phaseolus vulgaris. Random transposon mutagenesis was performed with the aim to identify novel genes of this strain involved in symbiosis and stress tolerance. The analysis of the locus disrupted by the Tn5 insertion in mutants 899-PV9 and 899-PV4 led the discovery of three novel genes required for and efficien...

  2. ?-Galactoside Uptake in Rhizobium meliloti: Isolation and Characterization of agpA, a Gene Encoding a Periplasmic Binding Protein Required for Melibiose and Raffinose Utilization

    OpenAIRE

    Gage, Daniel J.; Long, Sharon R.

    1998-01-01

    Rhizobium meliloti can occupy at least two distinct ecological niches; it is found in the soil as a free-living saprophyte, and it also lives as a nitrogen-fixing intracellular symbiont in root nodules of alfalfa and related legumes. One approach to understanding how R. meliloti alters its physiology in order to become an integral part of a developing nodule is to identify and characterize genes that are differentially expressed by bacteria living inside nodules. We used a screen to identify ...

  3. Potential for plant growth promotion in groundnut (Arachis hypogaea L.) cv. ALR-2 by co-inoculation of sulfur-oxidizing bacteria and Rhizobium.

    Science.gov (United States)

    Anandham, R; Sridar, R; Nalayini, P; Poonguzhali, S; Madhaiyan, M; Sa, Tongmin

    2007-01-01

    The use of Rhizobium inoculant for groundnut is a common practice in India. Also, co-inoculation of Rhizobium with other plant growth-promoting bacteria received considerable attention in legume growth promotion. Hence, in the present study we investigated effects of co-inoculating the sulfur (S)-oxidizing bacterial strains with Rhizobium, a strain that had no S-oxidizing potential in groundnut. Chemolithotrophic S-oxidizing bacterial isolates from different sources by enrichment isolation technique included three autotrophic (LCH, SWA5 and SWA4) and one heterotrophic (SGA6) strains. All the four isolates decreased the pH of the growth medium through oxidation of elemental S to sulfuric acid. Characterization revealed that these isolates tentatively placed into the genus Thiobacillus. Clay-based pellet formulation (2.5 x 10(7) cf ug(-1) pellet) of the Thiobacillus strains were developed and their efficiency to promote plant growth was tested in groundnut under pot culture and field conditions with S-deficit soil. Experiments in pot culture yielded promising results on groundnut increasing the plant biomass, nodule number and dry weight, and pod yield. Co-inoculation of Thiobacillus sp. strain LCH (applied at 60 kg ha(-1)) with Rhizobium under field condition recorded significantly higher nodule number, nodule dry weight and plant biomass 136.9 plant(-1), 740.0mg plant(-1) and 15.0 g plant(-1), respectively, on 80 days after sowing and enhanced the pod yield by 18%. Also inoculation of S-oxidizing bacteria increased the soil available S from 7.4 to 8.43 kg ha(-1). These results suggest that inoculation of S-oxidizing bacteria along with rhizobia results in synergistic interactions promoting the yield and oil content of groundnut, in S-deficit soils. PMID:16574388

  4. The Nodulation of Alfalfa by the Acid-Tolerant Rhizobium sp. Strain LPU83 Does Not Require Sulfated Forms of Lipochitooligosaccharide Nodulation Signals?

    OpenAIRE

    Torres Tejerizo, Gonzalo; Del Papa, María Florencia; Soria-Diaz, M. Eugenia; Draghi, Walter; Lozano, Mauricio; Giusti, María de los Ángeles; Manyani, Hamid; Megías, Manuel; Gil Serrano, Antonio; Pühler, Alfred; Niehaus, Karsten; Lagares, Antonio; Pistorio, Mariano

    2010-01-01

    The induction of root nodules by the majority of rhizobia has a strict requirement for the secretion of symbiosis-specific lipochitooligosaccharides (nodulation factors [NFs]). The nature of the chemical substitution on the NFs depends on the particular rhizobium and contributes to the host specificity imparted by the NFs. We present here a description of the genetic organization of the nod gene cluster and the characterization of the chemical structure of the NFs associated with the broad-ho...

  5. Rhizobium paranaense sp. nov., an effective N2-fixing symbiont of common bean (Phaseolus vulgaris L.) with broad geographical distribution in Brazil.

    Science.gov (United States)

    Dall'Agnol, Rebeca Fuzinatto; Ribeiro, Renan Augusto; Delamuta, Jakeline Renata Marçon; Ormeño-Orrillo, Ernesto; Rogel, Marco Antonio; Andrade, Diva Souza; Martínez-Romero, Esperanza; Hungria, Mariangela

    2014-09-01

    Nitrogen (N), the nutrient most required for plant growth, is key for good yield of agriculturally important crops. Common bean (Phaseolus vulgaris L.) can benefit from bacteria collectively called rhizobia, which are capable of fixing atmospheric nitrogen (N2) in root nodules and supplying it to the plant. Common bean is amongst the most promiscuous legume hosts; several described species, in addition to putative novel ones have been reported as able to nodulate this legume, although not always effectively in terms of fixing N2. In this study, we present data indicating that Brazilian strains PRF 35(T), PRF 54, CPAO 1135 and H 52, currently classified as Rhizobium tropici, represent a novel species symbiont of common bean. Morphological, physiological and biochemical properties differentiate these strains from other species of the genus Rhizobium, as do BOX-PCR profiles (less than 60?% similarity), multilocus sequence analysis with recA, gyrB and rpoA (less than 96.4?% sequence similarity), DNA-DNA hybridization (less than 50?% DNA-DNA relatedness), and average nucleotide identity of whole genomes (less than 92.8.%). The novel species is effective in nodulating and fixing N2 with P. vulgaris, Leucaena leucocephala and Leucaena esculenta. We propose the name Rhizobium paranaense sp. nov. for this novel taxon, with strain PRF 35(T) (?=?CNPSo 120(T)?=?LMG 27577(T)?=?IPR-Pv 1249(T)) as the type strain. PMID:24972614

  6. Study of vibrations and stabilization of linear collider final doublets at the sub-nanometer scale; Etude des vibrations et de la stabilisation a l'echelle sous-nanometrique des doublets finaux d'un collisionneur lineaire

    Energy Technology Data Exchange (ETDEWEB)

    Bolzon, B

    2007-11-15

    CLIC is one of the current projects of high energy linear colliders. Vertical beam sizes of 0.7 nm at the time of the collision and fast ground motion of a few nanometers impose an active stabilization of the final doublets at a fifth of nanometer above 4 Hz. The majority of my work concerned vibrations and active stabilization study of cantilever and slim beams in order to be representative of the final doublets of CLIC. In a first part, measured performances of different types of vibration sensors associated to an appropriate instrumentation showed that accurate measurements of ground motion are possible from 0.1 Hz up to 2000 Hz on a quiet site. Also, electrochemical sensors answering a priori the specifications of CLIC can be incorporated in the active stabilization at a fifth of nanometer. In a second part, an experimental and numerical study of beam vibrations enabled to validate the efficiency of the numerical prediction incorporated then in the simulation of the active stabilization. Also, a study of the impact of ground motion and of acoustic noise on beam vibrations showed that an active stabilization is necessary at least up to 1000 Hz. In a third part, results on the active stabilization of a beam at its two first resonances are shown down to amplitudes of a tenth of nanometer above 4 Hz by using in parallel a commercial system performing passive and active stabilization of the clamping. The last part is related to a study of a support for the final doublets of a linear collider prototype in phase of finalization, the ATF2 prototype. This work showed that relative motion between this support and the ground is below imposed tolerances (6 nm above 0.1 Hz) with appropriate boundary conditions. (author)

  7. Establecimiento y respuestas fisiológicas de la simbiosis Rhizobium tropici-Leucaena leucocephala en presencia de fenantreno y naftaleno / Establishment and physiological responses of the Rhizobium tropici-Leucaena leucocephala symbiosis in presence of phenanthrene and naphtalene

    Scientific Electronic Library Online (English)

    Carlos, LÓPEZ-ORTIZ; Ronald, FERRERA-CERRATO; Alejandro, ALARCÓN; Juan José, ALMARAZ; Esperanza, MARTÍNEZ-ROMERO; Ma. Remedios, MENDOZA-LÓPEZ.

    2012-11-01

    Full Text Available Este estudio evaluó el establecimiento de la simbiosis entre Rhizobium tropici CIAT899 y Leucaena leucocephala (Lam.) en sistemas contaminados con naftaleno (NAF) y fenantreno (FEN) y la respuesta de la planta con el contenido de compuestos fenólicos totales (CFT), actividad antioxidante total (AAT) [...] y contenido total de clorofilas (Clo-roT) y carotenos (CaT). A los 31 días, el NAF tuvo efectos negativos en la formación de nódulos, retardando su aparición hasta el día 25 en presencia de 100 mg/L. Ante 20 mg FEN/L, las plantas de L. leucocephala no mostraron diferencias significativas en la formación de nódulos con respecto al testigo, mientras que a 60 y 100 mg FEN/L la nodulación disminuyó significativamente en 52 %. La inoculación con R. tropici incrementó el peso seco total (PST) hasta en 150 % comparado con las plantas no inoculadas. El CFT en hoja fue significativamente mayor en los tratamientos no inoculados en comparación con aquellos inoculados con R. tropici y significativamente mayor ante FEN que con NAF. Para ambos contaminantes, la concentración de 100 mg/L produjo mayor CFT y AAT en comparación con 20 y 60 mg/L. Para el caso de raíz, los tratamientos sin contaminantes en ausencia de R. tropici presentaron mayor CFT y AAT. Para los nódulos, la AAT incrementó significativamente ante NAF, mientras que ante FEN disminuyó. El NAF o el FEN redujeron significativamente el contenido de CloroT, el cual fue significativamente mayor en plantas con Rhizobium en comparación con las plantas no inoculadas. El contenido de CaT en plantas no inoculadas incrementó en presencia de NAF y FEN. Abstract in english This study evaluated the establishment of the symbiosis between Rhizobium tropici CIAT899 and Leucaena leucocephala (Lam.) under contaminated systems with naphtalene (NAF) and phenanthrene (FEN), as well as the physiological plants responses such as total content of phenolic compounds (CFT), total a [...] ntioxidant activity (AAT) and the content of chlorophylls (CloroT) and carotenoids (CaT). After 31 days, NAF had more significant negative effects on nodulation by delaying the formation of nodules until the day 25 at 100 mg/L. In the presence of 20 mg FEN/L, L. leucocephala plants did not show significant differences on the number of nodules when compared to the control, while nodulation decreased 52 % at 60 and 100 mg FEN/L. Inoculation with R. tropici resulted in significant increases of PST (>150 %) in comparison to non-inoculated plants. The foliar content of CFT was significantly greater at non-inoculated treatments in respect to those with R. tropici, and significantly higher in plants exposed to FEN than NAF. For both hydrocarbons, the concentration of 100 mg/L resulted in greater CFT and AAT when compared to 20 or 60 mg/L. For roots, treatments without contamination and R. tropici had more content of CFT and AAT. The AAT in nodules significantly increased due to NAF, while a significant reduction was observed in FEN treatments. Either NAF or FEN did not significantly affect the content of CloroT, although this content was significantly greater in plants with R. tropici than non-inoculated plants. The CaT content significantly increased at non-inoculated plants exposed to NAF and/or FEN.

  8. Forestación de un terreno decapitado con Robinia pseudoacacia inoculada con Rhizobium spp. y Glomus deserticola / Afforestation of a desurfaced field with Robinia pseudoacacia inoculated with Rhizobium spp. and Glomus deserticola

    Scientific Electronic Library Online (English)

    Alejandro E, Ferrari; Carlos A, Esparrach; Mario A, Galetti; Luis G, Wall.

    2010-07-01

    Full Text Available Los terrenos decapitados constituyen un caso extremo de degradación de suelos aptos para agricultura, con graves consecuencias ambientales. El propósito de este trabajo fue ensayar los efectos de la inoculación de acacia blanca (Robinia pseudoacacia L.) con una cepa efectiva de Rhizobium y un hongo [...] de micorrizas arbusculares (Glomus deserticola) en la supervivencia y crecimiento temprano de plantas trasplantadas a un terreno decapitado de Balcarce, comparando con fresno como árbol no fijador de nitrógeno. La supervivencia inicial fue muy buena (mayor del 77%), especialmente para los fresnos y las acacias inoculadas, las cuales mostraron significativamente mayor supervivencia al estrés por sequía que las acacias control. Todas las plantas se mostraron igualmente tolerantes al ataque de liebres y al estrés por heladas tardías. Durante el primer año las acacias inoculadas crecieron más rápido que las no inoculadas. En el segundo año las alturas se equipararon en parte, probablemente por la colonización de las acacias control con rizobios o micorrizas naturales del suelo. De todos modos, las acacias inoculadas siempre mostraron valores mayores de los distintos parámetros de desarrollo (altura total, diámetro de la copa y cantidad de ramificaciones) que las plantas control, tanto en los sectores poco decapitados como en los más severamente degradados. En conclusión, la doble inoculación previa de acacia blanca mejoró la supervivencia inicial, aumentó tolerancia a la sequía y el crecimiento en 2 años y medio desde la plantación. Esta práctica de manejo sería entonces muy recomendable para reducir el período de vivero en la producción de árboles, así como lograr ejemplares más resistentes y mejor adaptados para proyectos de recuperación de suelos degradados. Abstract in english Many agricultural lands in Buenos Aires Province (Argentina) have traditionally been desurfaced for the manufacture of bricks and other building materials. The desurfaced soils represent an extreme situation of degradation, having severe consequences for the environment. The purpose of this work was [...] to assay the effects of inoculation of black locust (Robinia pseudoacacia L.) with Rhizobium and with a mycorrhizal strain on the survival and early growth of plants in a desurfaced field at the location of Balcarce (37º 45´ S, 58º 18´ O), in Buenos Aires Province (Argentina). The development of inoculated black locust was compared with non-inoculated (control) black locust and with the non-fixing green ash (Fraxinus pennsylvanica Marsh.). Survival after two months was very good (>77%), especially for Fraxinus and for inoculated plants. Furthermore, inoculated plants also showed a significantly higher survival rate under drought stress than the control plants. The three kinds of plants showed high tolerance to hare attack and to late frost stress. During the first year, inoculated plants grew more rapidly than non-inoculated controls. During the second year the height of the two treatments was quite similar, probably because of the nodulation of control plants with soil-borne rhizobial or mycorrhizal strains. However, inoculated plants always showed higher development than the control plants according to three growth parameters (total height, canopy diameter and amount of side branches), both in the intact parts of the field and in the most severely extracted sectors. In conclusion, prior inoculation of black locust with effective strains of Rhizobium and mycorrhizal fungi was able to improve initial survival, tolerance to drought and early growth. This management practice is highly recommended to reduce the greenhouse period in the production of trees, and to produce plants more resistant and better adapted to use in reclamation projects of degraded areas.

  9. Forestación de un terreno decapitado con Robinia pseudoacacia inoculada con Rhizobium spp. y Glomus deserticola Afforestation of a desurfaced field with Robinia pseudoacacia inoculated with Rhizobium spp. and Glomus deserticola

    Directory of Open Access Journals (Sweden)

    Alejandro E Ferrari

    2010-07-01

    Full Text Available Los terrenos decapitados constituyen un caso extremo de degradación de suelos aptos para agricultura, con graves consecuencias ambientales. El propósito de este trabajo fue ensayar los efectos de la inoculación de acacia blanca (Robinia pseudoacacia L. con una cepa efectiva de Rhizobium y un hongo de micorrizas arbusculares (Glomus deserticola en la supervivencia y crecimiento temprano de plantas trasplantadas a un terreno decapitado de Balcarce, comparando con fresno como árbol no fijador de nitrógeno. La supervivencia inicial fue muy buena (mayor del 77%, especialmente para los fresnos y las acacias inoculadas, las cuales mostraron significativamente mayor supervivencia al estrés por sequía que las acacias control. Todas las plantas se mostraron igualmente tolerantes al ataque de liebres y al estrés por heladas tardías. Durante el primer año las acacias inoculadas crecieron más rápido que las no inoculadas. En el segundo año las alturas se equipararon en parte, probablemente por la colonización de las acacias control con rizobios o micorrizas naturales del suelo. De todos modos, las acacias inoculadas siempre mostraron valores mayores de los distintos parámetros de desarrollo (altura total, diámetro de la copa y cantidad de ramificaciones que las plantas control, tanto en los sectores poco decapitados como en los más severamente degradados. En conclusión, la doble inoculación previa de acacia blanca mejoró la supervivencia inicial, aumentó tolerancia a la sequía y el crecimiento en 2 años y medio desde la plantación. Esta práctica de manejo sería entonces muy recomendable para reducir el período de vivero en la producción de árboles, así como lograr ejemplares más resistentes y mejor adaptados para proyectos de recuperación de suelos degradados.Many agricultural lands in Buenos Aires Province (Argentina have traditionally been desurfaced for the manufacture of bricks and other building materials. The desurfaced soils represent an extreme situation of degradation, having severe consequences for the environment. The purpose of this work was to assay the effects of inoculation of black locust (Robinia pseudoacacia L. with Rhizobium and with a mycorrhizal strain on the survival and early growth of plants in a desurfaced field at the location of Balcarce (37º 45´ S, 58º 18´ O, in Buenos Aires Province (Argentina. The development of inoculated black locust was compared with non-inoculated (control black locust and with the non-fixing green ash (Fraxinus pennsylvanica Marsh.. Survival after two months was very good (>77%, especially for Fraxinus and for inoculated plants. Furthermore, inoculated plants also showed a significantly higher survival rate under drought stress than the control plants. The three kinds of plants showed high tolerance to hare attack and to late frost stress. During the first year, inoculated plants grew more rapidly than non-inoculated controls. During the second year the height of the two treatments was quite similar, probably because of the nodulation of control plants with soil-borne rhizobial or mycorrhizal strains. However, inoculated plants always showed higher development than the control plants according to three growth parameters (total height, canopy diameter and amount of side branches, both in the intact parts of the field and in the most severely extracted sectors. In conclusion, prior inoculation of black locust with effective strains of Rhizobium and mycorrhizal fungi was able to improve initial survival, tolerance to drought and early growth. This management practice is highly recommended to reduce the greenhouse period in the production of trees, and to produce plants more resistant and better adapted to use in reclamation projects of degraded areas.

  10. Déserts et Thébaïdes (suite

    Directory of Open Access Journals (Sweden)

    Loïc Windels

    2012-06-01

    Full Text Available Faisant suite aux trois volets de notre analyse des traductions allemandes de l’incipit de Bouvard et Pécuchet, cet article se détache de la traduction comme pratique herméneutique pour la regarder au miroir d’autres approches du texte flaubertien, et en confirmer la lecture en la complétant, notamment par une attention portée aux noms propres, cet angle mort de la pratique traductive. Nous continuerons donc à rapprocher Antoine de Bouvard et Pécuchet, mais en recherchant cette fois la trace désertique du saint dans les anthroponymes et la topographie du roman parisien. Mais l’onomastique de Bouvard est, comme le roman lui-même, placé sous le signe de la copie, et il nous faudra donc chemin faisant élargir l’intertexte à Madame Bovary et à L’Éducation sentimentale.

  11. Anticholinergiques et hyperactivité vésicale

    OpenAIRE

    Qarro, Abdelmounaim; Asseban, Mohammed; Bazine, Khalil; Najoui, Mohammed; Samir, Jamaleddine; Ouhbi, Youssef; Beddouch, Amoqrane; Lezrek, Mohammed; Alami, Mohammed

    2014-01-01

    L’hyperactivité vésicale (HAV) (overactive bladder [OAB]) se caractérise par une urgenturie, avec ou sans incontinence urinaire, associée à une pollakiurie diurne (> 8 épisodes) et à une nycturie (> 1 épisode). Elle touche 27 % des hommes et 43 % des femmes de plus de 40 ans. Elle a d’importantes répercussions sur les activités quotidiennes ainsi que sur le profil psychologique et sexuel. Elle résulte d’une contraction anormale du détrusor liée à une stimulation de certains récepteurs muscari...

  12. Migrations et changements climatiques

    OpenAIRE

    Piguet, Etienne; Pécoud, Antoine; de Guchteneire, Paul

    2010-01-01

    Cet article propose un tour d’horizon des débats relatifs aux possibles conséquences migratoires du changement climatique. Après un bref historique, nous examinons l'impact sur les migrations des trois principaux facteurs environnementaux liés aux changements climatiques (cyclones tropicaux, fortes pluies et inondations ; sécheresses et désertification ; élévation du niveau de la mer). Les questions fondamentales que soulève la relation entre changement climatique et migration sont ensuite ab...

  13. Lydalfabetet : Et anderledes alfabet

    DEFF Research Database (Denmark)

    Lahti, Ulla; Louise, Skov

    2009-01-01

    Lydalfabetet er et danskudviklet fonemalfabet til brug i undervisningen af danske børn med verbal dyspraksi. Alfabetet er udarbejdet af en arbejdsgruppe under Dyspraksiforeningen. Udgivelsesdato: 2009

  14. Welfare state et développement

    Directory of Open Access Journals (Sweden)

    Celia Lessa Kerstenetzky

    2011-01-01

    Full Text Available Souvent, les rapports entre l'État du État-providence et le développement sont décrits comme source de problèmes et même de dilemmes. On présume, par exemple, que l'État du État-providence n'est possible que dans des pays développés, ou alors que la redistribution propre à l'Etat-providence a pour contrepartie une croissance économique moindre. Dans cet article, on cherche à réunir des arguments et justifications contraires à ces suppositions. Comme, par exemple, une démonstration sur la fonctionnalité de l'État-providence en faveur du développement, dans le sens économique et non-économique du terme.

  15. Recherche et développement

    Directory of Open Access Journals (Sweden)

    Icart Jean-Claude

    2000-03-01

    Full Text Available La présence des sciences sociales au centre de ce dossier, Afrique, plantation et développement, n’est pas seulement significative d’une situation propre au problème du développement des pays du Sud, et de l’Afrique en particulier. Les perspectives, au Nord, d’une agriculture multifonctionnelle, plus sensible aux dimensions territoriales et sociales des ses activités, confrontent la recherche agronomique à des problèmes similaires de médiation, liée aux mêmes impératifs de conciliation entre démarche scientifique et action, imposant le même recours aux analyses sur le milieu socio-économique.

  16. Produção de mudas de acácia colonizadas com micorrizas e rizóbio em diferentes recipientes / Production of acacia plants colonized with mycorrhizas and rhizobium in different recipients

    Scientific Electronic Library Online (English)

    Jolimar Antonio, Schiavo; Marco Antonio, Martins.

    2003-02-01

    Full Text Available Realizou-se um experimento em casa de vegetação, com o objetivo de avaliar diferentes métodos na produção de mudas de Acacia mangium Willd, colonizadas com fungos micorrízicos arbusculares (FMAs) e rizóbio. O delineamento experimental foi o inteiramente casualizado num esquema fatorial 4x2 (controle [...] , FMAs, rizóbio e FMAs + rizóbio x blocos prensados e tubetes de plástico), com seis repetições. Os blocos prensados foram confeccionados com substratos orgânicos (bagaço de cana + torta de filtro de usina açucareira) e vermiculita, colocados em fôrma metálica de 60x40x20 cm e prensados a 10 kgf cm-2, a fim de proporcionar agregação do material. A inoculação do rizóbio foi realizada com estirpe selecionada para a espécie (Br 3609, Br 6009). A inoculação de FMAs foi feita no momento da confecção dos blocos. Mudas de Acacia mangium que receberam inóculo de FMAs + rizóbio e produzidas em blocos prensados apresentaram maior produção de matéria seca e conteúdo de N na parte aérea. O conteúdo de P na parte aérea é significativamente maior somente nas mudas infectadas com os FMAs, independentemente do tipo de recipiente. Abstract in english A greenhouse experiment was carried out in order to evaluate different methods to produce Acacia mangium Willd plant seedlings, inoculated with arbuscular mycorrhizal fungi (AMF) and rhizobium. A completely randomized design in a factorial scheme 4x2 (control, AMF, rhizobium and AMF + rhizobium x pr [...] essed blocks and plastic tubes), with six repetitions was used. The pressed blocks used to produce Acacia mangium plants were made with organic residue from sugarcane (sugarcane bagasse + filter cake) and vermiculite. The inoculation with rhizobium was done with selected strain (Br 3609, Br 6009). The inoculation with AMF was done at the time when pressed blocks were made. Acacia mangium plants inoculated with both AMF + rhizobium led to a significant increase in dry matter yield and N content of shoot plants, only in pressed blocks. Phosphorus content of shoot plants is significantly higher in seedlings inoculated only with AMF, and it is independent of the plant production system.

  17. Topographie et topologie textuelles

    Directory of Open Access Journals (Sweden)

    Jean-Louis Lebrave

    2009-11-01

    Full Text Available Depuis ses débuts la statistique linguistique, y compris lorsqu’elle s’applique à l’étude des textes et des discours, a principalement recouru à des modèles qui tendent à négliger ce fait majeur qu’un texte est une structure ordonnée ; les dénombrements, les relevés de fréquences, les calculs de spécificités reposent tous sur le fameux schéma d’urne et renoncent à prendre en compte le positionnement dans le texte des unités dénombrées. Certes, les résultats ainsi obtenus sont généralement intéressants et bien interprétables, et ils ont largement contribué au développement et aux succès de la discipline. Mais ils se pourraient qu’ils soient en train d’atteindre leurs limites. Ou, du moins, de ne plus suffire pour donner entière satisfaction au chercheur. De plus en plus souvent en effet, ceux-ci souhaitent pouvoir établir, à côté de la dimension paradigmatique appréhendée par ce type de calculs statistiques traditionnels, la dimension syntagmatique des données textuelles, saisies à courte ou à longue portée : distribution régulière ou non d’une entité linguistique (mot ou catégorie grammaticale susceptible d’arriver à intervalles à peu près égaux ou, au contraire, en paquets plus ou moins denses ; répartition d’un élément au fil du texte, selon la structure globale de celui-ci et ses parties constituantes ; phénomènes d’échos et d’alignements dans la mise en parallèle de deux textes ou deux portions de textes ; etc. Bien sûr, des travaux, dont certains sont déjà anciens, ont abordé ces questions : parmi les plus connus citons tous ceux d’A. Salem qui ont établi la pertinence de la fameuse notion de « segment répété » et qui ont mis en place les outils pour les repérer et les analyser ; citons aussi les travaux de P. Lafon sur les « rafales » et son article "Statistique des localisations des formes d’un texte" paru en 1984 dans la revue Mots ; ou encore l’article de D. Sérant et Ph. Thoiron sur la « topographie des formes répétées » (Revue Informatique et Statistique dans les Sciences humaines 24, pp. 333-343 ; etc. Actuellement, cette question reprend de l’acuité et les études, ainsi que les développements logiciels afférents, se multiplient. Le moment nous semble donc venu de faire le point. Ce numéro de Lexicometrica accueillera donc exclusivement des contributions consacrées aux notions de topographie et topologie textuelles, c’est-à-dire à la prise en compte, dans les exploitations automatiques des textes numérisés et dans leur traitement quantitatif de la linéarité intrinsèque du texte, voire de sa structure en réseau avec d’autres textes au sein d’un corpus fortement cohérent (cas des recueils par exemple.

  18. Graphisme et géométrie

    CERN Document Server

    Fleury, Michel

    1986-01-01

    Une introduction à l'étude des rythmes visuels d'un point de vue géométrique et algorithmique. L'auteur montre le rôle de l'informatique dans la réalisation des dessins rythmiques et explique que la variété des rythmes visuels s'ordonne en classes distinctes associées à des algorithmes de production.

  19. RHIZOBIUM ETLI USDA9032 ENGINEERED TO PRODUCE A PHENAZINE ANTIBIOTIC INHIBITS THE GROWTH OF FUNGAL PATHOGENS BUT IS IMPAIRED IN SYMBIOTIC PERFORMANCE

    Science.gov (United States)

    Phenazine antibiotics produced by Pseudomonas spp. play a major role in preventing various plant diseases. In this study, the phenazine biosynthesis locus of P. chlororaphis O6, a plant growth-promoting rhizobacteria (PGPR), was introduced into several symbiotic bacteria belonging to the family Rh...

  20. Enfants, chercheurs et citoyens

    CERN Document Server

    Lederman, Leon

    1998-01-01

    J'ai consacré ma vie à la physique. J'aimerais que tous les enfants aient la chance de satisfaire leur goût pour la recherche et de développer leur intelligence. J'ai découvert à Chicago, chez mon ami Leon Lederman, une méthode d'enseignement des sciences à l'école qui m'a subjugué. J'ai vu, à tous les niveaux, en physique, en chimie, en sciences naturelles et en mathématiques, des enfants qui expérimentaient avec joie, apprenaient les concepts fondamentaux à leur rythme, réfléchissant et discutant. Je voyais en gestation des êtres libres, capables de rechercher une vérité qui ne leur était pas assenée. J'ai voulu confronter des enseignants français du primaire et du secondaire à ces recherches qui ne se limitent pas à l'enseignement primaire. C'est leur regard critique et surtout leurs idées pour notre enseignement que j'ai rassemblés dans ce livre.

  1. C. Petrone et al.: "Magnetic measurement of the model magnet QD0 designed for the CLIC final focus beam transport line." CERN TE-MSC Internal Note, EDMS Nr: 1184196

    CERN Document Server

    Arpaia, Pasquale; Petrone, Carlo; Russenschuck, Stephan; Walckiers, Louis

    2012-01-01

    This note presents the results of the magnetic measurements performed on QD0, model magnet for the final focus transport line for CLIC (Fig. 1). This high-gradient, hybrid quadrupole has a yoke length of 0.1 m and an aperture of 8.3 mm. ND2Fe14B Permanent magnet blocks provide a gradient of 150 T/m, which can be further increased to 530 T/m when the four coils are excited to 18.3 A. The request was to measure the strength of the field and the multipole coefficients at different currents. The measurement of the field strength, by means of the single stretched wire system, was done in December 2011 in the I8 laboratory. The measurement of the multipole was done by means of the oscillating wire system [1][2].

  2. Final environmental statement related to the operation of Catawba Nuclear Station, Units 1 and 2. Docket Nos. 50-413 and 50-414, Duke Power Company, et al

    International Nuclear Information System (INIS)

    This Final Environmental Statement contains the second assessment of the environmental impact associated with the operation of the Catawba Nuclear Station, Units 1 and 2, pursuant to the National Environmental Policy Act of 1969 (NEPA) and 10 CFR 51, as amended, of the NRC regulations. This statement examines: the affected environment, environmental consequences and mitigating actions, and environmental and economic benefits and costs. Land use and terrestrial and aquatic-ecological impacts will be small. Operational impacts to historic and archeological sites will be negligible. The effects of routine operations, energy transmission, and periodic maintenance of rights-of-way and transmission facilities should not jeopardize any populations of endangered or threatened species. No significant impacts are anticipated from normal operational releases of radioactivity. The risk associated with accidental radiation exposure is very low. The net socioeconomic effects of the project will be beneficial

  3. Économie urbaine et régionale au tournant du siècle

    OpenAIRE

    Georges Benko

    2007-01-01

    Cet article met en relation la géographie économique des années 1990 et les théories économiques les plus récentes. Cette partie de l’article construit une typologie de la recherche contemporaine en économie spatiale en évoquant les éléments essentiels des travaux autour des notions de : organisation industrielle, district, réseau, gouvernance, conventions, et finalement mettant en opposition le local et le global comme approches de recherche. La conclusion propose quelques pistes de recherch...

  4. Echantillonnage, interpolation et détection. Applications en imagerie satellitaire.

    OpenAIRE

    Almansa, Andrés

    2002-01-01

    Cette thèse aborde quelques-uns des problèmes qui surviennent dans la conception d'un système complet de vision par ordinateur : de l'échantillonnage à la détection de structures et leur interprétation. La motivation principale pour traiter ces problèmes a été fournie par le CNES et la conception des satellites d'observation terrestre, ainsi que par les applications de photogrammétrie et vidéo-surveillance chez Cognitech, Inc. pendant les étapes finales de ce travail, mais les techniques déve...

  5. Biologic fixation of nitrogen in irradiated rhizobium strips; Fixacao biologica do nitrogenio em estirpes de rizobianas irradiadas

    Energy Technology Data Exchange (ETDEWEB)

    Caribe, Rebeka Alves; Colaco, Waldeciro [Pernambuco Univ., Recife, PE (Brazil). Dept. de Energia Nuclear

    2002-07-01

    Native Rhizobium sp. and Bradyrhizobium sp. isolates from the root nodules of bean and cowpea were selected. Six isolates, and the SEMIA 4077 (R. leguminosarum bv. phaseolus) and SEMIA 6145 (Bradyrhizobium sp) strains used as references, were irradiated with ultraviolet light (R-uv) and gamma rays (R-{gamma}). The D{sub 37} values for the rhizobial strain SEMIA 4077 were 43 J.m{sup -2} (UV) and 32 Gy (R-{gamma}) and for the SEMIA 6145 were 45 J.m{sup -2} (UV) and 35 Gy (R-gamma). Through a greenhouse experiment the irradiated isolates were inoculated on bean (P. vulgaris L., cv. Princesa) and on cowpea [Vigna unguiculata, (L.) Walp, cv. IPA-206] seedlings, in an attempt to evaluate the sensitivity of the host plants, and possible effects on their nodulation. Differences in responses to nodulation due to the effect of irradiation were observed for the isolates tested. Significantly differences were observed only for nodules dry matter yield of the IPA-206 cultivar. Gamma irradiated treatment were statistically superior to treatments with ultraviolet light in relation. (author)

  6. Effect of N-rate and P sources on BNF in soybean as affected by rhizobium and VAM fungi lnoculants

    International Nuclear Information System (INIS)

    Greenhouse experiment was made to investigate the influence of phosphate fertilizers on nitrogen fixation in soybean. The N-15 isotope dilution method was used to quantify N 2-fixed. In this concern, seed of nodulated and on-nodulated soybean plant bacterized with Bradyrhizobium japonicum and noculated without or with mycorrhizas in the presence of super or rock phosphate. Ammonium sulphate labelled fertilizer (5% N-15 a.e) was applied o 15 kg sandy soil of egypt at the rate of 20 and 100 kg N/acre. At re-flowering stage, the highest amount of N derived from air (Ndfa) was 66.3 and 470.2 (mg/pot) equivalent 47.6 and 47.1 of total N assimilated for noculated soybean with Rhizobium and fertilized with super or rock phosphate, respectively. While the contributions from 15 N labelled fertilizer (Ndff) accounted for 11 and 10.8, respectively. Use of mycorrhizas could increase the amount of N 2-fixed in the presence of rhizobia. There appears to be a strong case for improving N 2-fixation in the presence of mycorrhizas especially in sandy soil. 4 tabs

  7. Rhizobium leguminosarum COMO ORGANISMO BIOCONTROLADOR DE LA INTERACCIÓN HOSPEDERO-PATÓGENO: CLAVEL (Dianthus caryophyllus – Fusarium Oxysporum f. sp. dianthi

    Directory of Open Access Journals (Sweden)

    Cheol Woo Lee Park

    2010-08-01

    Full Text Available Se investigó el efecto de biocontrol de Rhizobium leguminosarum (R. leguminosarum cepa B, contra Fusarium oxysporum f.sp.dianthi (FOD raza 2, en la interacción Clavel - FOD. Se utilizó la raza 2 de FOD por ser la de mayor patogenicidad y distribución en las fincas de cultivo de clavel en Colombia. Para ello se establecieron las condiciones de inoculación de FOD sobre cultivos establecidos de R . leguminosarum, variando la concentración in vitro de la bacteria. Se encontró una reducción en el número de microconidias hasta un 90% y una inhibición en el crecimiento radial del patógeno de hasta un 71 %. En el ensayo de microcultivo dual se detectó fraccionamiento de las hifas después de 48 horas de incubación con R . leguminosarum En el ensayo in vivo, los esquejes de clavel Raggio di solé, variedad susceptible al patógeno, fueron inoculados con 45.0 x 10 células de R. leguminosarum por matero, mostrando una severidad inferior al 5%, una incidencia menor del 20% y una reducción del índice de la enfermedad hasta de un 92% en presencia del patógeno.

  8. Enhanced Synthesis of Antioxidant Enzymes, Defense Proteins and Leghemoglobin in Rhizobium-Free Cowpea Roots after Challenging with Meloydogine incognita

    Directory of Open Access Journals (Sweden)

    Jose T. A. Oliveira

    2014-11-01

    Full Text Available The root knot nematodes (RKN, Meloydogine spp., particularly Meloidogyne incognita and Meloidogyne javanica species, parasitize several plant species and are responsible for large annual yield losses all over the world. Only a few available chemical nematicides are still authorized for RKN control owing to environmental and health reasons. Thus, plant resistance is currently considered the method of choice for controlling RKN, and research performed on the molecular interactions between plants and nematodes to identify genes of interest is of paramount importance. The present work aimed to identify the differential accumulation of root proteins of a resistant cowpea genotype (CE-31 inoculated with M. incognita (Race 3 in comparison with mock-inoculated control, using 2D electrophoresis assay, mass spectrometry identification and gene expression analyses by RT-PCR. The results showed that at least 22 proteins were differentially represented in response to RKN challenge of cowpea roots mainly within 4–6 days after inoculation. Amongst the up-represented proteins were SOD, APX, PR-1, ?-1,3-glucanase, chitinases, cysteine protease, secondary metabolism enzymes, key enzymes involved in ethylene biosynthesis, proteins involved in MAPK pathway signaling and, surprisingly, leghemoglobin in non-rhizobium-bacterized cowpea. These findings show that an important rearrangement in the resistant cowpea root proteome occurred following challenge with M. incognita.

  9. Evidence Suggesting Protozoan Predation on Rhizobium Associated with Germinating Seeds and in the Rhizosphere of Beans (Phaseolus vulgaris L.).

    Science.gov (United States)

    Ramirez, C; Alexander, M

    1980-09-01

    Changes in populations of microorganisms around germinating bean (Phaseolus vulgaris L.) seeds, in the rhizosphere of bean, and in a model rhizosphere were studied. Strains of Rhizobium phaseoli that were resistant to streptomycin and thiram were used, and as few as 300 R. phaseoli cells per g of soil could be enumerated with a selective medium that was devised. A direct role was not evident for bacterial competitors, lytic bacteria, antibiotic-producing microorganisms, bacteriophages, and Bdellovibrio in the suppression of R. phaseoli around germinating seeds and in the rhizosphere. Protozoa increased in numbers in the soil upon planting of the seeds. The extent of colonization of soil by R. phaseoli was inversely related to the presence of large numbers of bacteria and protozoa. Colonization of R. phaseoli was improved upon suppression of protozoa with thiram and also when the soil was amended with other protozoan inhibitors and mannitol to simulate seed and root exudation. The data support the view that the decrease in numbers of R. phaseoli is caused by an increase in protozoan predation, the protozoa increasing in number because they prey on bacteria that proliferate by using seed and root exudates as nutrients. PMID:16345628

  10. Production of (S)-4-chloro-3-hydroxybutyrate by microbial resolution using hydrolase from Rhizobium sp. DS-S-51.

    Science.gov (United States)

    Nakagawa, Atsushi; Suzuki, Takahiro; Kato, Ko; Shinmyo, Atsuhiko; Suzuki, Toshio

    2008-04-01

    (S)-4-Chloro-3-hydroxybutyrate (CHB) is essential for the synthesis of biologically and pharmacologically important compounds. Rhizobium sp. DS-S-51 isolated from soil samples showed hydrolytic activity toward (R)-CHB in the racemate to (R)-3-hydroxy-gamma-butyrolactone (HL) under a simple composition of the reaction. Residual (S)-CHB was obtained with high optical purity. The gene encoding the enzyme concerned, designated CHB hydrolase, was isolated from DS-S-51, and the gene was highly expressed in Escherichia coli JM109. When the resolution of racemic methyl CHB (CHBM) as a substrate was performed using this recombinant cell, JM109 (pKK-R1), the hydrolytic activity was found to be 40-fold greater than that of DS-S-51, and the maximum concentration of the substrate added increased 2-fold. Moreover, (R)-HL was also obtained without decreasing the optical purity compared with that when (R)-CHBM was used as a substrate. PMID:18499045

  11. Predominant nifH transcript phylotypes related to Rhizobium rosettiformans in field-grown sugarcane plants and in Norway spruce.

    Science.gov (United States)

    Burbano, Claudia Sofía; Liu, Yuan; Rösner, Kim Leonie; Reis, Veronica Massena; Caballero-Mellado, Jesus; Reinhold-Hurek, Barbara; Hurek, Thomas

    2011-06-01

    Although some sugarcane cultivars may benefit substantially from biological nitrogen fixation (BNF), the responsible bacteria have been not identified yet. Here, we examined the active diazotrophic bacterial community in sugarcane roots from Africa and America by reverse transcription (RT)-PCR using broad-range nifH-specific primers. Denaturing gradient gel electrophoresis (DGGE) profiles obtained from sugarcane showed a low diversity at all sample locations with one phylotype amounting up to 100% of the nifH transcripts. This major phylotype has 93.9-99.6% DNA identity to the partial nifH sequence from a strain affiliated with Rhizobium rosettiformans. In addition, nifH transcripts of this phylotype were also detected in spruce roots sampled in Germany, where they made up 91% of nifH transcripts detected. In contrast, in control soil or shoot samples two distinct nifH transcript sequences distantly related to nifH from Sulfurospirillum multivorans or Bradyrhizobium elkanii, respectively, were predominant. These results suggest that R. rosettiformans is involved in root-associated nitrogen fixation with sugarcane and spruce, plants that do not form root-nodule symbioses. PMID:23761284

  12. Direct amplification of nodD from community DNA reveals the genetic diversity of Rhizobium leguminosarum in soil.

    Science.gov (United States)

    Zézé, A; Mutch, L A; Young, J P

    2001-06-01

    Sequences of nodD, a gene found only in rhizobia, were amplified from total community DNA isolated from a pasture soil. The polymerase chain reaction (PCR) primers used, Y5 and Y6, match nodD from Rhizobium leguminosarum biovar trifolii, R. leguminosarum biovar viciae and Sinorhizobium meliloti. The PCR product was cloned and yielded 68 clones that were identified by restriction pattern as derived from biovar trifolii [11 restriction fragment length polymorphism (RFLP) types] and 15 clones identified as viciae (seven RFLP types). These identifications were confirmed by sequencing. There were no clones related to S. meliloti nodD. For comparison, 122 strains were isolated from nodules of white clover (Trifolium repens) growing at the field site, and 134 from nodules on trap plants of T. repens inoculated with the soil. The nodule isolates were of four nodD RFLP types, with 77% being of a single type. All four of these patterns were also found among the clones from soil DNA, and the same type was the most abundant, although it made up only 34% of the trifolii-like clones. We conclude that clover selects specific genotypes from the available soil population, and that R. leguminosarum biovar trifolii was approximately five times more abundant than biovar viciae in this pasture soil, whereas S. meliloti was rare. PMID:11472501

  13. Biological control of crown gall on grapevine and root colonization by nonpathogenic Rhizobium vitis strain ARK-1.

    Science.gov (United States)

    Kawaguchi, Akira

    2013-01-01

    A nonpathogenic strain of Rhizobium vitis ARK-1 was tested as a biological control agent for grapevine crown gall. When grapevine roots were soaked in a cell suspension of strain ARK-1 before planting in the field, the number of plants with tumors was reduced. The results from seven field trials from 2009 to 2012 were combined in a meta-analysis. The integrated relative risk after treatment with ARK-1 was 0.15 (95% confidence interval: 0.07-0.29, P0.001), indicating that the disease incidence was significantly reduced by ARK-1. In addition, the results from four field trials from 2007 to 2009 using R. vitis VAR03-1, a previously reported biological control agent for grapevine crown gall, were combined in a meta-analysis. The integrated relative risk after treatment with VAR03-1 was 0.24 (95% confidence interval: 0.11-0.53, P0.001), indicating the superiority of ARK-1 in inhibiting grapevine crown gall over VAR03-1 under field conditions. ARK-1 did not cause necrosis on grapevine shoot explants. ARK-1 established populations on roots of grapevine tree rootstock and persisted inside roots for two years. PMID:23708779

  14. Complete genome sequence of Rhizobium leguminosarum bv. trifolii strain WSM1325, an effective microsymbiont of annual Mediterranean clovers.

    Energy Technology Data Exchange (ETDEWEB)

    Reeve, Wayne [Murdoch University, Perth, Australia; O' Hara, Graham [Murdoch University, Perth, Australia; Chain, Patrick S. G. [Lawrence Livermore National Laboratory (LLNL); Ardley, Julie [Murdoch University, Perth, Australia; Brau, Lambert [Murdoch University, Perth, Australia; Nandesena, Kemanthi [Murdoch University, Perth, Australia; Tiwari, Ravi [Murdoch University, Perth, Australia; Copeland, A [U.S. Department of Energy, Joint Genome Institute; Nolan, Matt [U.S. Department of Energy, Joint Genome Institute; Han, Cliff [Los Alamos National Laboratory (LANL); Brettin, Thomas S [ORNL; Land, Miriam L [ORNL; Ovchinnikova, Galina [U.S. Department of Energy, Joint Genome Institute; Ivanova, N [U.S. Department of Energy, Joint Genome Institute; Mavromatis, K [U.S. Department of Energy, Joint Genome Institute; Markowitz, Victor [U.S. Department of Energy, Joint Genome Institute; Kyrpides, Nikos C [U.S. Department of Energy, Joint Genome Institute; Melino, Vanessa [Murdoch University, Perth, Australia; Denton, Matthew [Department of Primary Industries, Victoria, Australia; Yates, Ron [Murdoch University, Perth, Australia; Howieson, John [Murdoch University, Perth, Australia

    2010-01-01

    Rhizobium leguminosarum bv trifolii is a soil-inhabiting bacterium that that has the capacity to be an effective nitrogen fixing microsymbiont of a diverse range of annual Trifolium (clover) species. Strain WSM1325 is an aerobic, motile, non-spore forming, Gram-negative rod isolated from root nodules collected in 1993 from the Greek Island of Serifos. WSM1325 is manufactured commercially in Australia as an inoculant for a broad range of annual clovers of Mediterranean origin due to its superior attributes of saprophytic competence, nitrogen fixation and acid-tolerance. Here we describe the basic features of this organism, together with the complete genome sequence, and annotation. This is the first completed genome sequence for a microsymbiont of annual clovers. We reveal that its genome size is 7,418,122 bp encoding 7,232 protein-coding genes and 61 RNA-only encoding genes. This multipartite genome contains 6 distinct replicons; a chromosome of size 4,767,043 bp and 5 plasmids of size 828,924, 660,973, 516,088, 350,312 and 294,782 bp.

  15. 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

  16. Maize growth promotion by inoculation with Azospirillum brasilense and metabolites of Rhizobium tropici enriched on lipo-chitooligosaccharides (LCOs).

    Science.gov (United States)

    Marks, Bettina Berquó; Megías, Manuel; Ollero, Francisco Javier; Nogueira, Marco Antonio; Araujo, Ricardo Silva; Hungria, Mariangela

    2015-12-01

    There is an increasing interest in the development and use of inoculants carrying plant growth-promoting bacteria (PGPB) in crops of agronomic interest. The great majority of the inoculants commercialized worldwide contain rhizobia for legume crops, but the use of PGPB as Azospirillum spp. for non-legume is expanding, as well as of inoculants combining microorganisms and microbial metabolites. In this study we evaluated the effects of inoculants containing Azospirillum brasilense with or without metabolites of Rhizobium tropici strain CIAT 899 highly enriched in lipo-chitooligosaccharides (LCOs) in six field experiments performed for three summer crop seasons in Brazil with maize (Zea mays L.). Inoculants and metabolites were applied either at sowing by seed inoculation, or by leaf spray at the V3 stage of plant growth. Improvement in shoot dry weight (SDW) and total N accumulated in shoots (TNS) by single, but especially by dual inoculation was observed in some of the experiments. Statistically significant increases in grain yield in relation to the non-inoculated control were observed in five out of six experiments when maize was inoculated with Azospirillum supplied with enriched metabolites of R. tropici applied by seed or leaf spray inoculation. The results give strength to the development of a new generation of inoculants carrying microorganisms and microbial molecules. PMID:26567001

  17. Interacción de Tsukamurella paurometabola C-924 con Rhizobium leguminosarum biovar phaseoli CFH en el cultivo de frijol

    Directory of Open Access Journals (Sweden)

    Marieta Marín Bruzos

    2013-01-01

    Full Text Available En el estudio se evaluaron, mediante análisis de los parámetros fenológicos de las plantas, la interacción de Tsukamurella paurometabola C-924 con Rhizobium leguminosarum biovar phaseoli CFH en el cultivo de frijol. Se emplearon cuatro tratamientos: plantas sin inocular (control, inoculadas con T. paurometabola C-924, inoculadas con R. leguminosarum biovar phaseoli CFH e inoculadas con ambas cepas. Se observaron diferencias significativas (P < 0.01 en los porcentajes de germinación de las plantas tratadas con microorganismos de forma independiente o conjunta con respecto al control sin inocular. Se determinó que la inoculación de T. paurometabola C-924 afectó el proceso de nodulación de R. leguminosarum biovar phaseoli CFH. Sin embargo, esto no incidió de manera significativa en la altura de las plantas ni en el diámetro del tallo, ya que no se encontraron diferencias entre los tratamientos para estos parámetros. Para el número de hojas, los mejores resultados se obtuvieron con la aplicación de T. paurometabola C-924. Se concluyó que la interacción de T. paurometabola C-924 con R. leguminosarum biovar phaseoli CFH en el frijol estimuló significativamente la germinación de las semillas y el número de hojas de las plantas con respecto al control sin inocular. Aunque la aplicación de T. paurometabola C-924 no favoreció la nodulación de R. leguminosarum biovar phaseoli CFH, esto no afectó las características fenológicas del cultivo.

  18. Drague et cruising

    Directory of Open Access Journals (Sweden)

    Emmanuel Redoutey

    2008-04-01

    Full Text Available Dans la culture homosexuelle masculine, drague et cruising sont des termes équivalents. Ils désignent la quête d’un ou de plusieurs partenaires occasionnels et anonymes. Analyser leurs référents métaphoriques respectifs offre un éclairage particulier, à la fois phénoménologique et géographique, pour une compréhension nuancée des types de pratique et d’expérience qu’ils recouvrent. Cet article pose l’hypothèse d’une distinction entre deux figures, le dragueur et le cruiser, et postule que cette distinction se tient essentiellement dans l’opposition que Gilles Deleuze et Félix Guattari établissent entre ‘espace strié’ et ‘espace lisse’. L’essai de théorisation qui en découle est une manière de comprendre ce qui, entre sexualisation de l’espace et érotisation d’un mouvement exploratoire, fait fonctionner le script de la drague.In French gay culture, drague means cruising: looking for anonymous and ?casual sexual partners. This paper, by respectively examining the ?metaphorical underpinnings of both words, French and English, throws ?doubt on the validity of this translation. Through a phenomenological ?and geographical perspective, it attempts to give a nuanced examination ?of the practice and experience that each word conceals. The aim is to ?identify two figures embodied in a same person: the dragueur and the ?cruiser. I will argue that the distinction mainly rests on the ?opposition that Gilles Deleuze and Felix Guattari establish between ‘striated space’ and ‘smooth space’. The concluding theorical ?discussion is an attempt to understand what, in the tension between sexualization of space and eroticization of movement, guides the scripts of drague and cruising.

  19. Villes et nouvelle économie

    Directory of Open Access Journals (Sweden)

    Emmanuel Éveno

    2003-06-01

    Full Text Available Cet article analyse les modes d’insertionspatiale des technologies de l’information et de la communication (TIC dans les métropoles puis aborde la question des mythes d’une «antigéographie» soulevés par cette nouvelle vague d’innovations dont les postulats sont basés sur les effets de réseaux et les technologies de lutte contre la distance. Trois approches (hiérarchie urbaine, réorganisation de l’espace métropolitain, nouveaux objets urbains essaient de montrer toute la place de la géographie et des problématiques territoriales autour des TIC.

  20. Durkheim et le Collectivisme.

    OpenAIRE

    Didry, Claude

    2015-01-01

    Ce texte est issu d'une intervention au colloque "DROIT ET SOCIOLOGIE (1860-1939).?Moment juridique de la sociologie ou moment sociologique du droit?", organisé les 20 et 21 juin 2013 par Mélanie Plouviez et Frédéric Audren. Il propose un retour sur les différentes formes d'appropriation de la sociologie durkheimienne, dans un objectif réformiste, en mettant notamment au jour l'importante contribution de Jaurès qui dans sa présentation de la société collectiviste de l'avenir, se fonde sur la ...

  1. Démographie et mouvement

    OpenAIRE

    Christophe Terrier

    2010-01-01

    La statistique ne s’accorde pas facilement avec le mouvement. On définit des cases et on mesure  ce qu’on trouve dans chacune des cases. Quand des individus se promènent d’une case à l’autre, on est obligé de faire intervenir le temps : la mesure se réfère alors à une période, définie par une date de début et une date de fin. Mais quand le mouvement se fait plus rapide, obtenir une mesure de bonne qualité exigerait de réduire la période de référence à un instant très court et de répéter l’opé...

  2. Imprensa política e pensamento republicano no Paraná no final do XIX / Presse politique et pensée républicaine dans l'état du Paraná à la fin du XIXème siècle / Political journalism and republican thought in late 19th century Paraná

    Scientific Electronic Library Online (English)

    Amélia Siegel, Corrêa.

    2009-02-01

    Full Text Available A crise do regime monárquico brasileiro veio acompanhada do surgimento e da expansão do movimento republicano, no final do século XIX. No período, a imprensa não somente colocou-se como palco dos debates institucionais, como também teve papel de poder informal, vinculado ao governo e à organização p [...] artidária. Tratava-se de uma imprensa de opinião, que tinha como um de seus eixos os comentários partidários. As colunas dos jornais eram usadas para escrever anonimamente o que não podia ser dito publicamente na Assembléia, Senado ou Câmara, constituindo um fórum de discussão alternativo à tribuna. Este artigo busca recuperar os modelos de República que circularam nesses periódicos paranaenses, relacionando-os com as configurações nas quais estavam inseridos e com a posição que ocupavam no campo do poder local e nacional. Todavia, vale lembrar que os ideários republicanos dominantes não foram disseminados sem resistência no Paraná; ao contrário, foram detectados e combatidos localmente, porém sem força política suficiente. Parte-se da perspectiva bourdiesiana de que os discursos não são unicamente signos destinados a serem compreendidos e decifrados, mas também indicativos de status, que se propõem a ser valorados e apreciados, e de autoridade, a serem cridos e obedecidos, por constituírem um objeto da luta simbólica pelo poder. A análise dos discursos republicanos mostra que a política paranaense do final do século XIX era mais um resultado de alianças e desavenças entre grupos do que fruto de posicionamentos ideológicos. Os discursos serviam, majoritariamente, como armas retóricas utilizadas para orientar o enfrentamento intra-elites, movido pelo desejo de participação, o que fez com que tivesse um caráter genérico, alicerçado na concepção do fim dos privilégios, embora sem a ampliação da cidadania. Abstract in english The crisis of the Brazilian monarchical regime was accompanied by the emergence and expansion of the republican movement at the end of the 19th century. During that period, the press not only became the stage of institutional debates but also had the role of an informal power, linked to the governme [...] nt and political party organization. It was a press that expressed opinions and created a space for partisan commentary. Newspaper columns were used to anonymously air that which could not be expressed publicly in the Legislative Assembly, the Senate or the House of Representatives, thus constituting an alternative tribune for debate. This article seeks to give voice to the different republican models that circulated within these state of Paraná newspapers, relating them to the configurations they were a part of and with the position that they held within local and national fields of power. Furthermore, it is important to recognize that the dominant republican ideas were not disseminated without resistance: rather, they were heard and combated at the local level, although efforts in this regard remained lacking in political force. Our analysis incorporates the Bourdieusian perspective according to which discourses are not only signs to be understood and decoded but also status indicators -seeking to be validated and evaluated - and forms of authority, seeking to be believed and obeyed; in both cases, object of struggles over symbolic power. Analysis of republican discourse shows that Paraná state politics of the late 19th century was more a result of alliances and tensions between groups than the fruit of clear ideological stands. Discourses served mostly as rhetorical weapons which were used to orient intra-elite conflict, moved by the desire for participation. This gave them a generic character, based on a notion of putting an end to privilege without widening citizenship rights.

  3. Lipochimie et innovations

    OpenAIRE

    Alfos Carine

    2003-01-01

    Peut-on parler d’un nouvel âge d’or pour les produits à base de ressources végétales renouvelables et notamment pour les huiles ? Porteurs de performances spécifiques et de caractéristiques plus écologiquement correctes, leur emploi ouvre à l’industrie un potentiel d’innovations auquel participe le département de chimie et rhéologie de l’Iterg. La prise de conscience collective, associée aux évolutions des réglementations françaises et européennes, devrait conduire les industries à prendre de...

  4. Convexité et Optimisation

    OpenAIRE

    Cohen, Guy

    2000-01-01

    Préface Introduction Éléments d'analyse fonctionnelleEnsembles convexesFonctions convexesOptimisation sous contraintes : conditions d'optimalité localesConditions d'optimalité globales et techniques LagrangiennesLagrangien augmenté

  5. Peirce et Wittgenstein

    OpenAIRE

    Tiercelin, Claudine

    2000-01-01

    Analyse des nombreux points communs mais aussi des différences réelles entre les deux auteurs, notamment sur la question de l'éthique, du pragamtisme, de la psychologie, mais aussi de la métaphysique et de la science.

  6. Éducation et Libération

    CERN Multimedia

    Jean-Pierre Lagnaux

    2012-01-01

    Vente d’artisanat du Tiers Monde Jeudi 22 et Vendredi 23 novembre de 10 heures à 16 heures 30 Après nos réalisations en Amérique latine et au Bénin, nous mobilisons nos efforts pour l’école Arc-en-ciel de Kpeme, au Togo, sur les bords de l’Océan, à mi-chemin entre Lome et la frontière entre le Bénin et le Togo. Il s’agit d’une école primaire privée, laïque qui a très bonne réputation en termes de résultats, notamment pour les écoliers en fin de scolarité primaire. Cela fait plusieurs années déjà que nous soutenons cette école. L’école est inscrite dans la liste des  Collectes à long terme  de l’Association du personnel du CERN depuis 2011. Selon les  R&am...

  7. Dialogisme et polyphonie

    Directory of Open Access Journals (Sweden)

    Robert Vion

    2011-12-01

    Full Text Available La présente conférence part des grandes orientations issues des écrits de Bakhtine centrés sur la notion de dialogisme et examine quelques conséquences, pour l’analyse linguistique, de l’adoption d’une problématique dialogique. Elle s’efforce, dans un second temps, de confronter la notion de polyphonie, apparue dans son ouvrage de 1929 portant sur les romans de Dostoïevsky, à la polyphonie énonciative théorisée par Ducrot à la suite des travaux de Bally. Après une présentation de la distinction entre locuteur et énonciateur, et une argumentation visant à montrer que le locuteur ne saurait se retirer de l’énonciation, nous examinons un ensemble de phénomènes, exprimant la coexistence de voix dans le discours, qui relèvent à la fois de la polyphonie et du dialogisme. Ces deux notions sont alors examinées selon un continuum permettant de souligner aussi bien leur proximité que leur différence.

  8. Géoadvertainment et géoéthique

    OpenAIRE

    Denise Pumain

    2009-01-01

    L’Europe a choisi 2009 pour célébrer la créativité et l’innovation. Pour la créativité, la géographie n’est pas en reste : après la (pléonasmique) géolocalisation, la géocomputation, la géovisualisation, la géosimulation, voici que les cartes animées et les images de synthèse en trois dimensions s’invitent dans les présentations géographiques. Armés de ces outils nouveaux, les géographes savent faire voir, tout en amusant le public. Auraient-ils assimilé déjà ce nouvel avatar de la « communic...

  9. Gestion et mondialisation

    Directory of Open Access Journals (Sweden)

    Jean-Luc Metzger

    2010-10-01

    Full Text Available L’économie mondiale est en crise. Apparue dans la sphère financière globalisée, cette « crise » se serait propagée à l’économie réelle planétaire, laquelle, pour s’adapter, exige des élites politiques qu’elles interviennent et encouragent la mise en œuvre d’instruments de gestion portant sur l’emploi, l’organisation du travail ou les relations avec les différents marchés (clients et fournisseurs. Une telle vision, dominante, naturalise la production des dynamiques contemporaines. Elle présen...

  10. DÉRIVATION ALLEMANDE ET TRADUCTION

    OpenAIRE

    Silvia BONCESCU

    2011-01-01

    Dans le domaine du lexique allemand, la dérivation, qui n’utilise pas forcément préfixes et suffixes dans leur sens traditionnel, témoigne d’une grande vitalité des structures lexicales, notamment dans la langue de la presse. Nous étudierons de plus près des exemples tirés d’un corpus de presse écrite et nous verrons quelles sont les difficultés de traduction auxquelles nous nous confrontons.

  11. Dynamique de la flore et de la végétation des Niayes et du Bassin arachidier au Sénégal

    Directory of Open Access Journals (Sweden)

    Elhadji Faye

    2014-12-01

    Full Text Available Reactualisation of floristic and phytosociologic datas in Niayes and Peanut-Basin areas were undertook with village scale approach to better underline resources' conervation. In Savannah and sub-guinean areas specially in the Peanut-Basin and Niayes, 288 floristic samples were put in place in 6 villages in an stratified way based on ethnic groups, land use systems and topography. In the same time, 25 samples were realised in the 2 reference sites (Noflaye and Sambandé and comparison were made with researches conducted in 1940. Datas were submitted to multivariate analysis. SØrensen similarity index were used to compare villages systems and natural sites. Results showed discrimination of 11 phytosociologic groups: 5 of which came from natural sites (savanah G4 Hexalobus monopetalus et Gardenia ternifolia and G8 Acacia macrostachya et Ischaemum rugosum, secondary forest G10 Aphania senegalensis et Voaganca africana, semi-aquatic vegetations G1 Ipomoea aquatica et I. dichroa and G5 Phragmites australis subsp australis et Paspalum vaginatum and 6 from anthropic systems (disturbed areas G6 Echinochloa colona et Jussiae erecta and G7 Dactyloctenium aegyptium et Brachiaria disticophylla, and finally post-cultural zones with G2 Brachiaria disticophylla et Cenchrus biflorus, G3 Celosia trigyna et Digitaria velutina, G9 Tephrosia purpurea et Cenchrus biflorus and G11 Mitracarpus scaber et Eragrostis tremula. Natural sites groups were progressively invided by disturded area species and the others by ruderals and nitrophyl species. Overall floristic richness is about 336 species among which 260 from the Niayes sites and 176 from Peanut-Basin ones. References sites are always richer in terms af genera but peul areas are richer in termes of species. Differences were evidenced between actual taxa and Trochain (1940 descriptions. This methodological approach might be extended to other ecogeographical zones in Senegal in order to better identify and follow phyotosociologic groups dynamics and facilitate their integration in modern classification. Keywords : Senegal, flora, phytosociology groups, dynamics.

  12. Des racines et des ailes

    Directory of Open Access Journals (Sweden)

    Stéphanie Vincent-Geslin

    2012-05-01

    Full Text Available Les mobilités pendulaires semblent être en augmentation en Europe depuis une dizaine d’années. Cette croissance du temps passé à se déplacer amène à remettre en question la conjecture de Zahavi et apparaît relativement inexplicable en regard du paradigme classique de l’acteur rationnel traditionnellement utilisé dans le champ des transports. Si, dans la littérature, les temps de déplacements sont principalement expliqués par le contexte résidentiel, la forme urbaine et le travail, ce cadre explicatif ne dit rien des processus de décision eux-mêmes qui amènent aux pendularités intensives.À partir d’une enquête qualitative menée auprès de pendulaires français, suisses et belges, cette contribution propose d’analyser les arbitrages et les éléments déterminants des processus de la grande pendularité. Les mobilités quotidiennes pendulaires apparaissent comme le résultat de compromis entre activité professionnelle, attachement résidentiel et choix de vie et prennent ainsi la forme de stratégies de conciliation entre vie privée et vie professionnelle. Ces mobilités spatiales permettent alors paradoxalement la préservation des ancrages résidentiels, sociaux et familiaux.Roots and wings. Long-distance commuting patterns, or how to conciliate professional and personal lifeLong-distance commuting patterns appear to be increasing in Europe over the last ten years. These raising mobility patterns lead to reappraise the Zahavi conjecture and appear largely inexplicable by the classical rational actor paradigm traditionally used in transportation research. In literature, commuting is mainly explained by residential contexts, urban forms and job. Nevertheless this theoretical frame says little about the decision-making processes themselves. Based on a qualitative survey conducted in three European countries - France, Belgium and Switzerland – among a population of high commuters, this paper proposes an analysis of trade-off and elements implied in the decision-making process of becoming a long-distance commuter. Intense commuting patterns appear to be the result of compromises between job career, residential attachment and life choices. Thus they may be a “happy medium” that allows to conciliate professional and personal life. Finally these spatial mobilities paradoxically allow to preserve residential, social and family anchors.De raíces y de alas. La movilidad pendular como estrategia de conciliación entra la vida privada y la vida profesionalLas movilidades pendulares parecen aumentar en Europa desde hace una década. Esta aumentación del tiempo consagrado a los desplazamientos nos lleva a poner en entredicho la conjetura de Zahavi porque es relativamente inexplicable con relación al paradigma clásico del actor racional, habitualmente utilizado en el ámbito de los transportes. Si en los diferentes estudios realizados el tiempo utilizado en los transportes es explicado por el contexto de la residencia, la forma urbana y el trabajo, este marco explicativo no evoca siquiera los procesos de decisión que inducen pendularidades intensivas. A partir de una encuesta cualitativa llevada a cabo sobre grupos « pendulares » franceses, suizos y belgas, esta contribución propone el análisis de las mediaciones y de los elementos determinantes en estos procesos. Las movilidades cotidianas pendulares son una manera de asumir el compromiso entre actividad profesional, lugar de residencia y elección de modo de vida y toman la forma de estrategias de conciliación entre lo privado y lo profesional. Estas movilidades espaciales permiten paradójicamente de preservar el enraizamiento residencial, profesional y familiar.

  13. Le beau et le vrai

    Directory of Open Access Journals (Sweden)

    Létitia Mouze

    2006-05-01

    Full Text Available La vie des abeilles de Maeterlinck est un ouvrage à la fois scientifique et littéraire, non pas parce qu’il appartiendrait à la science par son exactitude et à la littérature par son style, mais en ce qu’il invite à penser l’unité des deux domaines. Les aspects littéraires de l’ouvrage (beauté de l’écriture, usage des images, de l’analogie, etc. ne sont pas des accessoires, mais des outils indispensables à l’élaboration d’un authentique savoir sur les abeilles, c’est-à-dire un savoir qui reconnaît la part d’inconnu et le mystère qui subsistent en dépit de toutes les explications physiques et mécaniques que l’on peut par ailleurs donner des phénomènes observés. Etre scientifique, dans cette perspective, c’est-à-dire donner à connaître, c’est donc être littéraire. Cette conception de la science repose en dernière instance sur une conception philosophique de l’univers comme un tout où toutes choses sont reliées, unies, par des relations d’analogies, ce qui fonde et justifie l’emploi d’un style symboliste.The life of bees, one of Maeterlinck’s works, is together a scientific and literary book, not because of it scientific exactness and its literary style, but for the reason it suggests the unity of both these domains. Literay’s aspects of this work (writing’s beauty, use of images, analogy, etc. are not secondary but necessary to elaborate an authentic knowledge about bees, that means a knowledge which admit the unknown part and the mistery that subsist despite all the physical and mechanical explanations we can give moreover about the observed phenomenons. Be a scientist, in this sense, that is give something to know, therefore means be literary. Finally, this conception of science consist in a philosophiacl conception of Universe as a whole where everything links together, and is united by analogical relations, that base and justify the use of a symbolist style.

  14. Théorie de la justice et idéologie : Hume et Rawls

    Directory of Open Access Journals (Sweden)

    Eléonore Le Jallé

    2008-04-01

    Full Text Available Les points d’accord entre Rawls et Hume vont au-delà du seul repérage des « circonstances de la justice ». Même si Hume se trouve attaché à la théorie utilitariste de l’impartialité que Rawls rejette, Hume n’est pas, selon Rawls, « à proprement parler » utilitariste : il a su reconnaître l’idée selon laquelle les institutions doivent fonctionner dans l’intérêt de chacun. L’idée d’une coopération sociale en vue de l’avantage mutuel est donc commune à ces deux auteurs. Ils partagent, en outre, une attitude similaire face au « problème de la confiance » en lien avec la stabilité de la justice : l’un et l’autre ajoutent ainsi à la solution extérieure qu’est l’institution étatique, un facteur intrinsèque de stabilité, à savoir, le sens de la justice. L’idée de « justice procédurale » et le rejet, corrélatif, d’un critère indépendant du juste, les relie également ; d’où, enfin, une certaine analogie des critiques respectivement adressées à ces deux auteurs.The specification of the “circumstances of justice” is not the only point on which Rawls agrees with Hume. If Rawls rejects the utilitarian theory of impartiality which is “reminiscent of Hume”, he does not consider him as “strictly speaking utilitarian”. Indeed, Rawls thinks that Hume has well understood that institutions have to be to the advantage of everyone. Besides, Hume and Rawls agree in thinking that the stability of justice involves a public sense of justice. Finally, the idea of “pure procedural justice” is shared by these authors: both have rejected any independent criterion for the right result, so that the ways they were criticized are rather similar.

  15. Fiction et forme encyclopédique : Wookieepedia, Dragon Ball Wiki et Cie.

    Directory of Open Access Journals (Sweden)

    Benoît Berthou

    2011-06-01

    Full Text Available Wookieepedia, Final Fantasy Wiki, Dragon Ball Wiki, Memory Alpha, WoWWiki… Autant d’encyclopédies en ligne abordant de célèbres fictions pour la jeunesse à travers un nombre parfois considérable d’articles abordant toutes sortes de sujets (récits, technologies, personnages, lieux, auteurs, fans…. Que nous apprennent ces dispositifs entendant prendre des fictions au sérieux, c’est-à-dire aborder un domaine relevant de l’imaginaire avec des outils relevant du domaine de la connaissance ? Deux pratiques se dégagent : la référence à des produits culturels prenant des formes fort diverses (romans, bandes dessinées, films, jeux vidéo… et le lien entre les divers articles. Ces deux pratiques montrent comment se développe une expertise quant à une fiction, une capacité à se situer dans une construction imaginaire.

  16. 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.

  17. Isolation and identification of an EPS-producing Rhizobium strain from arid soil (Algeria): characterization of its EPS and the effect of inoculation on wheat rhizosphere soil structure.

    Science.gov (United States)

    Kaci, Yahia; Heyraud, Alain; Barakat, Mohamed; Heulin, Thierry

    2005-05-01

    The production of exopolysaccharides (EPSs) by bacterial populations in the rhizosphere has been demonstrated to contribute to water and nutrient uptake by plant roots through the modification of the physical properties of rhizosphere soil. We report here the characterization of a new EPS produced by a bacterial strain (KYGT207) isolated from an arid soil in southern Algeria (Gassi Touil), and the effect of inoculation of this strain on soil physical properties in the rhizosphere of Triticum durum L. Strain KYGT207 was assigned to the genus Rhizobium by 16S ribosomal DNA sequencing and belongs to a new species closely related to Rhizobium sullae. The EPS produced by this strain was found to be composed of glucose (Glc), galactose (Gal), and mannuronic acid (ManA) in a molar ratio of 2:1:1. The primary structure of the EPS was determined by sugar analysis, 1D and 2D NMR spectroscopy, consisting of a tetrasaccharide repeating unit with the following original structure: [structure: see text]. A rheological analysis showed that this EPS could be considered as a thickening agent with polyelectrolyte properties. Inoculation of wheat plantlets with strain KYGT207 caused significant promotion of plant growth (+85% for shoot dry mass and +56% for root dry mass), a significant increase in root-adhering soil (RAS) dry mass (dm) per root dm (RAS/RT) up to 137%, and in RAS aggregate water stability. We demonstrate that EPS-producing bacteria were present in sandy soils subjected to water stress and that EPS-producing Rhizobium populations play an important role in the rhizosphere through their contribution to soil aggregation. PMID:15862451

  18. Aspects Technologiques et Developpementaspects Technologiques et Developpement

    Directory of Open Access Journals (Sweden)

    Sebedio Jean-Louis

    2001-07-01

    Full Text Available L’acide linoléique conjugué (CLA est présent dans les aliments d’origine animale, en particulier ceux issus des ruminants. Le CLA peut aussi être synthétisé au laboratoire par isomérisation alcaline de l’acide linoléique. Alors que l’isomère naturel est le 18 : 2 9c,11t, les produits de synthèse contiennent principalement deux isomères, les 18 : 2 9c,11t et 10t,12c. De nombreuses études menées sur des modèles animaux, le plus souvent avec des mélanges synthétiques, montrent des effets potentiellement bénéfiques pour la santé (anticarcinogènes, protecteurs vis-à-vis de l’athérosclérose, modulateurs de la composition corporelle… alors que la plupart des études menées chez l’homme concernent les effets des CLA sur la composition corporelle. À ce jour, les données concernant les effets sur la composition corporelle chez l’homme semblent indiquer un bénéfice potentiel, mais les résultats restent controversés. Par ailleurs, bien qu’un effet anticarcinogène soit démontré chez l’animal, aucune étude chez l’homme n’a pu établir de relation entre CLA et cancer du sein. De plus, peu d’études traitant des aspects sécuritaires liés à la consommation à long terme ont été publiées. Par conséquent, il est nécessaire de disposer de plus de données en particulier chez l’Homme pour garantir l’innocuité de ces acides gras afin de protéger le consommateur, avant d’envisager l’utilisation de CLA dans des aliments fonctionnels.

  19. Isolation and characterization of a DNA replication origin from the 1,700-kilobase-pair symbiotic megaplasmid pSym-b of Rhizobium meliloti.

    OpenAIRE

    Margolin, W.; Long, S R

    1993-01-01

    A 4-kb fragment active as an autonomously replicating sequence (ARS) from the Rhizobium meliloti symbiotic megaplasmid pSym-b was isolated by selecting for sequences that allowed a normally nonreplicative pBR322 derivative to replicate in R. meliloti. The resulting Escherichia coli-R. meliloti shuttle plasmid (mini-pSym-b) containing the ARS also replicated in the closely related Agrobacterium tumefaciens, but only in strains carrying pSym-b, suggesting that a megaplasmid-encoded trans-acting...

  20. Characterization of genes for synthesis and catabolism of a new rhizopine induced in nodules by Rhizobium meliloti Rm220-3: extension of the rhizopine concept.

    OpenAIRE

    Saint, C. P.; Wexler, M.; Tempé, J; Tate, M E; Murphy, P J

    1993-01-01

    Rhizopines are selective growth substrates synthesized in nodules only by strains of rhizobia capable of their catabolism. We report the isolation and study of genes for the synthesis and catabolism of a new rhizopine, scyllo-inosamine (sIa), from alfalfa nodules induced by Rhizobium meliloti Rm220-3. This compound is similar in structure to the previously described rhizopine 3-O-methyl-scyllo-inosamine from R. meliloti L5-30 (P.J. Murphy, N. Heycke, Z. Banfalvi, M.E. Tate, F.J. de Bruijn, A....

  1. Isolation and characterization of mutants of Rhizobium leguminosarum bv. viciae 248 with altered lipopolysaccharides: possible role of surface charge or hydrophobicity in bacterial release from the infection thread.

    OpenAIRE

    Maagd, R.A., de; Rao, A. S.; Mulders, I H; Goosen-de Roo, L; Loosdrecht, M.C., van; Wijffelman, C. A.; Lugtenberg, B J

    1989-01-01

    Effects of alterations in lipopolysaccharide (LPS) structure of Rhizobium leguminosarum bv. viciae on effective symbiosis and on a number of cell surface characteristics were studied. Tn5 mutants with altered LPSs were screened for their inability to bind monoclonal antibody 3, one of three monoclonal antibodies to the tentative O-antigenic part of the wild-type LPS of strain 248. Ten class I LPS mutants completely lacked the O-antigen-containing LPS species. The class II LPS mutant had a sev...

  2. Islam et engagements au Sénégal

    OpenAIRE

    Kaag, M.M.A.

    2011-01-01

    Ce volume collectif rassemble les résultats de travaux menés par des chercheurs sénégalais et néerlandais selon trois axes de recherche concernant le Sénégal: la relation entre islam et politique, la relation entre islam et économie, le rôle de l'islam dans le débat public sur la bonne gouvernance. Faisant suite à une introduction par Mayke Kaag intitulée 'Islam et engagements au Sénégal', les textes des contributions ont pour titre: Islam et politique au Sénégal: logique d'articulation et de...

  3. Greenhouse effect gases sources and sinks (CO{sub 2}, CH{sub 4}, N{sub 2}O) in grasslands and reduction strategies. Greenhouse effect gases prairies. Final report of the second part of the project. April 2004; Sources et puits de gaz a effet de serre (CO{sub 2}, CH{sub 4}, N{sub 2}O) en prairie paturee et strategies de reduction. GES-Prairies. Rapport final de la seconde tranche du projet. Avril 2004

    Energy Technology Data Exchange (ETDEWEB)

    Soussana, J.F

    2004-04-15

    The project 'GES-Prairies' (Greenhouse Gases - Grasslands) had two main objectives: 1. To measure more accurately the fluxes of CO{sub 2}, CH{sub 4} and N{sub 2}O of French grasslands and determine the greenhouse gas (GHG) balance of these areas. 2. To calculate the net GHG emissions of cattle production farms and finally to propose and evaluate some management scenarios leading to a reduction of GHG emissions. This project deals with three different spatial scales: the field scale, the farm scale and finally, the regional scale. At the field scale, during two years, fluxes of CO{sub 2}, CH{sub 4} and N{sub 2}O were measured in a mid-mountain permanent grassland, previously managed intensively by cutting and grazing (Laqueuille, Auvergne, France). Results from the first complete year of measurements show that the extensification process (reduction of the stocking rate and stopping N fertilization) allows to stock more carbon in the ecosystem. At the farm scale, We developed a model (FARMSIM, coupled to PASIM) able to simulate the GHG balance of a livestock farm. FARMSIM has been tested with data obtained from a mixed livestock farm in Lorraine (dairy and meat production, annual average stocking rate = 1.3 LU ha{sup -1}) of 100 ha (including 76 ha of grasslands and 21 of annual crops). The results indicate a net emission of 175 t equivalent C-CO{sub 2} for this farm. If expressed per unit of product, it represents 1.34 t equivalent C-CO{sub 2} per LU and per year or 0.54 kg CO{sub 2} per kg of milk and per year. At the regional scale/. The PASIM model has been used to simulate the European grasslands with a spatial resolution of 1' (about 200 * 200 km). For each grid cell, a sensibility analysis allowed to determine the N application which correspond to 30% of the N application that would maximize the annual yield of the pasture. Simulation runs on mixed systems (combining grazing and cutting) show that almost one half of the grassland area is, on average, used for cutting. These simulations predict N{sub 2}O emission factors that are relatively stable for the different grid cells across Europe wit values ranging between 1 and 2% in cut systems and between 3 and 4% under grazing (with organic N application through faeces and urine deposition). Under cutting, the simulations predict a important annual C storage (varying between 0.5 to 6 t C ha-1 y-1). However one must consider that an important part of this storage occurs in the harvested forage. C storage in grazed grasslands (0.3 to 2 t C ha-1 y-1) is lower than in cut grasslands. The simulations indicates therefore that cut grassland could represent an important net GHG sink. In France, the amplitude of this sink could vary between 0.5 and 2 t C CO{sub 2} equivalent ha-1 y-1. The simulations combining cut and grazed grassland, in proportion to the dietary needs, show that,in France, these systems would be a net GHG sink of 2 to 3 t C CO{sub 2} equivalent ha-1 y-1. More realistic results would be obtained if the differences between farming systems were taken into account more specifically. (author)

  4. La balle et la plume

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    Peter Marquis

    2012-06-01

    Full Text Available Fin octobre 2008, la nouvelle fit l’effet d’une bombe : Barack Obama, alors candidat à la présidence américaine, demanda à la chaîne câblée Fox News de retarder le début du sixième match de la World Series de base-ball afin de diffuser un spot de campagne. Son adversaire, John McCain, soutenu par le camp républicain et une partie de la population, monta aussitôt au créneau pour dénoncer l’hérésie : s’arroger le droit de perturber cette grande finale du championnat au déroulement immuable reve...

  5. Final report of the project. Emission of nitrogen oxides by the soils. Measures, modelization, land registry and inventory. Impact on the air quality, the climatic change and the evaluation of possibilities of these emissions reduction; Rapport final du projet. Emissions d'oxydes d'azote par les sols. Mesures, modelisation, cadastre et inventaire. Impact sur la qualite de l'air, le changement climatique, et evaluation des gisements de reduction de ces emissions

    Energy Technology Data Exchange (ETDEWEB)

    Serca, D.; Cortinovis, J. [LA Laboratoire d' Aerologie UMR 5560, 31 - Toulouse (France); Laville, P.; Gabrielle, B. [Institut National de Recherches Agronomiques (INRA), Environnement et Grandes Cultures, 78 - Thiverval-Grignon (France); Beekmann, M.; Ravetta, F. [Universite Pierre et Marie Curie, SA Service d' Aeronomie, 75 - Paris (France); Henault, C. [Institut National de Recherches Agronomiques (INRA-LMS) UMR Microbiologie des Sols-Geosol, 21 - Dijon (France)

    2007-07-01

    This project deals with NOx biosphere-atmosphere exchanges, NOx being considered as an indirect greenhouse gases (tropospheric O{sub 3} precursor). It relies on four laboratory specialized both on the soil-plant-atmosphere interface, and on the atmospheric chemistry. Methodology used bear on a set of in situ and laboratory measurements aiming at improving existing emission parameterization, or building new ones for the agro-ecosystems encountered in France or Europe. In situ measurements allowed to study the emission phenology in relation with relevant environmental parameters (meteorological, soil characteristics, and agricultural). Laboratory measurements allowed to establish an emission algorithm related to the three main parameters, that is, soil temperature, water and ammonia content. This algorithm has been adapted and simplified to spatialize the emissions at the France level. This spatialization was performed using environmental parameters accessible through data base (ECMWF) or agricultural statistics (such as nitrogen inputs, land use, crops). Spatial and temporal extrapolation allowed reaching the main objective, that is, to build a national inventory for a reference year (2002). This inventory allowed determining the contribution of NOx emitted by soil as compared to total emitted NOx, and the proportion of NOx emitted by soil due to fertilizer use. Our study, based on 57% of the French used agricultural area, and extrapolated to the whole arable surface, shows that soils would be responsible of about 5% of the total NOx emissions. On these 5%, 20%, which finally is a rather low percentage, would be linked to fertilizer use. The impact of these emissions on the atmospheric chemistry has been evaluated using the CHIMERE chemistry-transport model. We found that NOx emissions from soil would be of minor importance when compared to the industrial emissions, being a factor of ten lower in France. As a matter of consequence, the impact of the emissions on the maximum ozone concentration during summer months is relatively limited over Europe, but can reach 2 to 3 ppb for some of the rural French regions. (author)

  6. Formatversionering. Et overblik

    Directory of Open Access Journals (Sweden)

    Pia Majbritt Jensen

    2005-09-01

    Full Text Available Formatversionering spiller en stadig større rolle i den internationale tv- branche. Formater som “Big Brother” og “Vild med dans” findes på lokale tv-skærme i store dele af verden. En rapport fastslog for nylig, at formathandlen alene i Danmark i 2004 havde en anslået værdi på €60 mio., et tal der sandsynligvis er steget yderligere siden da (Sch- mitt et al. 2005. Artiklen gennemgår en række centrale aspekter ved de seneste års eksplosive formatudvikling. Først redegør artiklen for, hvad et tv-formater. Dernæst opridses, hvorfor formatversionering har fået en stadig stigende betydning internationalt. Hvilke fordele indeholder formatversionering sammenlignet med alternativerne, egenproduktion og indkøb af originale udenlandske programmer? Herefter argumente- res der for at se formaterne som del af en transnational mediekultur, i og med at de på den ene side er et resultat af den økonomiske, tekno- logiske og kulturelle globalisering, mens de på den anden side produce- res lokalt og foregår på lokale sprog, med lokale medvirkende. I for- længelse heraf gennemgås en konkret case – formatet “Ground Force” (på dansk “Hokus Krokus” – der illustrerer, hvor forskelligt to lokale versioneringer af det samme format kan tage sig ud. Til slut gives et overblik over de centrale positioner inden for den sparsomme forskning, der er udført på området, inden artiklen i en perspektiverende konklusion peger på vigtige aspekter ved fænomenet, en fremtidig forskning på om- rådet bør afdække.

  7. PssP2 is a polysaccharide co-polymerase involved in exopolysaccharide chain-length determination in Rhizobium leguminosarum.

    Science.gov (United States)

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

    2014-01-01

    Production of extracellular polysaccharides is a complex process engaging proteins localized in different subcellular compartments, yet communicating with each other or even directly interacting in multicomponent complexes. Proteins involved in polymerization and transport of exopolysaccharide (EPS) in Rhizobium leguminosarum are encoded within the chromosomal Pss-I cluster. However, genes implicated in polysaccharide synthesis are common in rhizobia, with several homologues of pss genes identified in other regions of the R. leguminosarum genome. One such region is chromosomally located Pss-II encoding proteins homologous to known components of the Wzx/Wzy-dependent polysaccharide synthesis and transport systems. The pssP2 gene encodes a protein similar to polysaccharide co-polymerases involved in determination of the length of polysaccharide chains in capsule and O-antigen biosynthesis. In this work, a mutant with a disrupted pssP2 gene was constructed and its capabilities to produce EPS and enter into a symbiotic relationship with clover were studied. The pssP2 mutant, while not altered in lipopolysaccharide (LPS), displayed changes in molecular mass distribution profile of EPS. Lack of the full-length PssP2 protein resulted in a reduction of high molecular weight EPS, yet polymerized to a longer length than in the RtTA1 wild type. The mutant strain was also more efficient in symbiotic performance. The functional interrelation between PssP2 and proteins encoded within the Pss-I region was further supported by data from bacterial two-hybrid assays providing evidence for PssP2 interactions with PssT polymerase, as well as glycosyltransferase PssC. A possible role for PssP2 in a complex involved in EPS chain-length determination is discussed. PMID:25268738

  8. Rhizobium leguminosarum bv. trifolii rosR is required for interaction with clover, biofilm formation and adaptation to the environment

    Directory of Open Access Journals (Sweden)

    Piersiak Tomasz

    2010-11-01

    Full Text Available Abstract Background Rhizobium leguminosarum bv. trifolii is a symbiotic nitrogen-fixing bacterium that elicits nodules on roots of host plants Trifolium spp. Bacterial surface polysaccharides are crucial for establishment of a successful symbiosis with legumes that form indeterminate-type nodules, such as Trifolium, Pisum, Vicia, and Medicago spp. and aid the bacterium in withstanding osmotic and other environmental stresses. Recently, the R. leguminosarum bv. trifolii RosR regulatory protein which controls exopolysaccharide production has been identified and characterized. Results In this work, we extend our earlier studies to the characterization of rosR mutants which exhibit pleiotropic phenotypes. The mutants produce three times less exopolysaccharide than the wild type, and the low-molecular-weight fraction in that polymer is greatly reduced. Mutation in rosR also results in quantitative alterations in the polysaccharide constituent of lipopolysaccharide. The rosR mutants are more sensitive to surface-active detergents, antibiotics of the beta-lactam group and some osmolytes, indicating changes in the bacterial membranes. In addition, the rosR mutants exhibit significant decrease in motility and form a biofilm on plastic surfaces, which differs significantly in depth, architecture, and bacterial viability from that of the wild type. The most striking effect of rosR mutation is the considerably decreased attachment and colonization of root hairs, indicating that the mutation affects the first stage of the invasion process. Infection threads initiate at a drastically reduced rate and frequently abort before they reach the base of root hairs. Although these mutants form nodules on clover, they are unable to fix nitrogen and are outcompeted by the wild type in mixed inoculations, demonstrating that functional rosR is important for competitive nodulation. Conclusions This report demonstrates the significant role RosR regulatory protein plays in bacterial stress adaptation and in the symbiotic relationship between clover and R. leguminosarum bv. trifolii 24.2.

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

    Science.gov (United States)

    Esther Boboye, Bolatito; Ajayi, George Olarewaju

    2012-01-01

    This study was carried out to determine the ability of Rhizobium species CWP G34B to degrade the peels of selected Nigerian fruits. The potential of the bacterium to digest some carbon sources (lactose, maltose, sucrose and mannitol) and peels of some Nigerian fruits (pineapple, orange, plantain, banana, pawpaw and mango fruits) was investigated by growing the organism on the substances separately after which DNSA reagent method was used to quantify glucose released into the medium. The results showed that the bacterium was able to degrade all the carbohydrates with the highest and the lowest glucose concentrations of 5.52 mg/ml for lactose and 0.50 mg/ml for mannitol. The carbohydrate-catabolic-enzyme (CCE) activity ranged from 0.169 mg/ml to 1.346 mg/ml glucose per mg/ml protein. Mannitol exhibited the highest CCE activity while the lowest activity was observed in the presence of sucrose. The amount of extracellular protein synthesized was highest (9.803 mg/ml) in the presence of maltose and lowest (0.925 mg/ml) in mannitol. The mean polygalacturonase activity was 0.54 unit/ml when the bacterium was grown in pectin in contrast to 0.28 unit/ml when it was grown in mannitol. The bacterium showed ability to breakdown the peels of the Nigerian fruits with the highest capability in banana and pineapple (0.42 and 0.41 mg/ml glucose per mg/ml protein respectively). The fruit-peel-degrading enzyme activity was lowest in orange peel (0.75 unit/ml). PMID:23166567

  10. Regulation of exopolysaccharide synthesis in Rhizobium sp. strain TAL1145 involves an alternative sigma factor gene, rpoH2.

    Science.gov (United States)

    Kaufusi, Pakieli H; Forsberg, L Scott; Tittabutr, Panlada; Borthakur, Dulal

    2004-10-01

    Exopolysaccharide (EPS) produced by Rhizobium sp. strain TAL1145 has been shown to be essential for effective nodulation on Leucaena leucocephala (leucaena). This paper reports the isolation and characterization of an alternative sigma factor gene, rpoH2, involved in the regulation of EPS synthesis in TAL1145. Disruption of this gene in TAL1145 resulted in a Calcofluor-dim mutant RUH102 that produced approximately 18 % of the amount of EPS made by TAL1145. This mutation did not affect the normal growth of RUH102 in free-living state. RUH102 induced few nitrogen-fixing nodules, resulting in a significant reduction in total nitrogen content in leucaena. It was complemented for EPS production and nodulation by a 2.0 kb HindIII fragment of TAL1145. Sequence analysis of this fragment revealed the rpoH2 ORF of 870 bp that encoded a protein of 32 kDa. Expression of the rpoH2 ORF in Escherichia coli also revealed a 32 kDa protein. A PCR-constructed clone of 1263 bp, containing the rpoH2 ORF and its upstream putative regulatory region, complemented RUH102 for EPS defects. Comparison of the RpoH2 sequence to proteins in the databases showed significant similarity to RpoH-like sigma factors of other Gram-negative bacteria. By constructing several exo : : Tn3Hogus fusions and transferring them to the backgrounds of TAL1145 and RUH102, it was demonstrated that RpoH2 positively regulates the transcription of some exo genes. PMID:15470124

  11. Diaspora grecque et francophonie aux XXe et XXIe siècles

    Directory of Open Access Journals (Sweden)

    Efstratia Oktapoda-Lu

    2012-09-01

    Full Text Available Consacré aux auteurs grecs en exil, l’article d’Efstratia Oktapoda-Lu analyse un corpus d’œuvres publiées en français, où se déclinent différentes façons d’aborder la mémoire et la construction identitaire de l’individu, entre oubli et nostalgie, entre conflit et équilibre, entre retour fantasmé et expérience de la double culture.

  12. Aspects Technologiques et Developpementaspects Technologiques et Developpement

    OpenAIRE

    Sebedio Jean-Louis; Bretillon Lionel; Chardigny Jean-Michel

    2001-01-01

    L’acide linoléique conjugué (CLA) est présent dans les aliments d’origine animale, en particulier ceux issus des ruminants. Le CLA peut aussi être synthétisé au laboratoire par isomérisation alcaline de l’acide linoléique. Alors que l’isomère naturel est le 18 : 2 9c,11t, les produits de synthèse contiennent principalement deux isomères, les 18 : 2 9c,11t et 10t,12c. De nombreuses études menées sur des modèles animaux, le plus souvent avec des mélanges synthétiques, montrent des effets potent...

  13. Littérature et bande dessinée. Enjeux et limites

    Directory of Open Access Journals (Sweden)

    Jan Baetens

    2009-05-01

    Full Text Available Le présent article se propose d’examiner deux aspects majeurs de la rencontre entre littérature et bande dessinée, dont le champ ne peut être limité à celui des seules adaptations de textes littéraires en bande dessinée. D’une part, il propose une définition de la bande dessinée littéraire (ou du roman graphique, peu importe la terminologie qui met l’accent sur le concept de récit, plus particulièrement sur le concept de récit visuel, pour analyser ensuite quels types de récits visuels sont considérés comme littéraires en bande dessinée. D’autre part, il démontre que l’analyse littéraire de la bande dessinée peut aider considérablement à renouveler l’étude de certains aspects de la théorie narrative, notamment dans le domaine du discours autobiographique et des techniques du feuilleton.This article deals with two crucial aspects of the encounter between literature and comics, which cannot be reduced to the mere problem of the adaptation of literary texts in comics. On the one hand, it offers a new definition of the literary comics (or graphic novel, although this kind of terminological discussions will be avoided here, which puts a strong emphasis on the concept of storytelling, more precisely of visual storytelling, and it analyzes which types of storytelling may be considered literary in the comics field. On the other hand, it argues that the literary reading of comics may prove dramatically helpful in the elaboration of new ways of interpreting narrative theory, for instance in the domain of autobiography as well as in the domain of the instalment techniques.

  14. Entre exotisme et nostalgie

    Directory of Open Access Journals (Sweden)

    Caroline Rozenholc

    2008-03-01

    Full Text Available En 1992, la municipalité de Tel-Aviv Jaffa, sollicitée par un groupe d’habitants, décide d’investir dans le quartier de Florentin. Florentin est alors un des quartiers les plus pauvres de la ville et témoigne, comme l’ensemble de la zone administrative sud, d’un état de forte dégradation. En quelques décennies, le quartier aura en effet été littéralement déserté par sa population, laissant vacants des centaines de logements progressivement investis par de petites industries. Le potentiel du quartier est pourtant évident – architecture unique et forte densité commerciale – et les réhabilitations réussies des quartiers de Neve Tseddek et de Sheinkin encouragent les autorités à « remettre Florentin sur la carte ». Cinq ans plus tard, Eytan Fox – plus connu aujourd’hui pour son film « The Bubble » – prend le quartier comme toile de fond pour réaliser une chronique de la jeunesse israélienne : « Florentin ». Pendant trois ans, cette série télévisée va obtenir une audience nationale confirmée par une rediffusion récente. Florentin est alors consacré comme un espace « à part » et devient emblématique d’une urbanité alternative. Paré d’une aura d’exotisme, renforcée par la présence de nombreux migrants africains, Florentin devient ainsi le lieu d’une certaine culture israélienne : celle d’une génération ouverte à l’altérité et qui, tout en étant ancrée dans la réalité du pays, se projette au-delà de ses frontières. Mêlant sens et temporalités, une conjoncture particulière fait donc émerger Florentin comme un label ; vivre à Florentin devient une véritable « déclaration d’intention ».En transition vers une gentrification évidente, comment ce quartier, longtemps marginalisée et qui n’est inclus dans les limites administratives de Tel-Aviv que depuis les années 50, en est venu à former une entité à part entière au sein de l’agglomération et à promouvoir l’identité globalisée de la ville ? Pour répondre à cette question, et pour contribuer à celle plus vaste de l’attachement au lieu dans la mondialisation, Florentin sert d’ancrage à une réflexion sur le quartier qui permet d’alimenter, entretiens et observations à l’appui, le débat entre tenants de l’hyper-mobilité et des nons-lieux et ceux d’une territorialité au fondement de la géographie et de l’urbanité. Florentin, espace complexe et stimulant, et dont on peut multiplier les « entrées », semble alors indiquer une troisième voie ; celle d’un lieu défini et ouvert où s’articulent, sans s’effacer, des temporalités et des perceptions du lieu distincts et propres, même si parfois partagées, à chacun.Florentin between exoticism and nostalgia.Globalization of an 'authentic' neighborhoodAt the beginning of the 90s, the Municipality of Tel-Aviv, approached by a small group of inhabitants of Florentin neighborhood, decides to invest in it. Florentin, at the time, is one of the poorest areas of the city and alike the whole South of Tel-Aviv, it is in an advanced state of deterioration. Over the last twenty years, buildings had fallen apart and all the population who had opportunities to leave the neighborhood found better dwellings. At the time, the potential of the neighborhood is nevertheless clear to the authorities – due to its peculiar architecture and the interesting mixture of residential and commercial activities – and the successful rehabilitations of both Neve Tseddek (the first Jewish neighborhood out the walls of the ancient Jaffa and Sheinkin street (today a very hype place to hang out stimulate the Municipality to “put Florentin back on the map”. This is a radical step as for few decades Florentin remained very much at the margins of the city, in between Tel-Aviv and Jaffa, only loosing population and gaining in polluting activities, such as small industries and manufactures. After few years of drastic investments, and due to an economical crisis, all initiatives remain pendin

  15. Adultère et romantisme

    Directory of Open Access Journals (Sweden)

    Annik Houel

    2010-05-01

    Full Text Available En ce début de XIXème siècle, le combat que mène George Sand pour le droit des femmes à l’amour s’inscrit dans la tradition d’une contestation - qu’on peut qualifier de féministe - qui porte essentiellement sur les conditions du mariage, le plus souvent arrangé. Le leitmotiv de l’amour, qui traverse les oeuvres de la plupart des femmes qui l’ont précédée en littérature manifeste leur opposition au mariage tel qu’il leur est imposé, et l’adultère symbolise leur rêve : ainsi en va-t-il, dès le Moyen-Âge, pour Marie de France, Christine de Pisan, Marguerite de Navarre même, et bien sûr pour Madame de La Fayette avec La Princesse de Clèves qui incarne le clivage psychique entre corps et esprit auquel les femmes sont alors acculées.

  16. Qualité et action publique

    Directory of Open Access Journals (Sweden)

    Marc Mormont

    2011-09-01

    Full Text Available L'article examine les conséquences pour l'action publique de la généralisation des procédures de qualité. Dans une première partie, la qualité est analysée historiquement comme un processus par lequel l'incertitude est réduite, essentiellement à l'intérieur du monde industriel, par des négociations entre entrepreneurs. La croissance de l'Etat social fait ensuite apparaître toutes les normes de qualité standard qui se réfèrent à des biens publics mais dont la production est largement déléguée à des experts et des négociations sectorielles sur un mode néo-corporatiste. Ceci élargit et confirme le modèle de la délégation de la qualité qui est conforme au schéma durkheimien de la production des normes.Trois évolutions récentes sont analysées. La première est l’entrée de la qualité dans le débat public qui élargit l’espace de demandes sociales de qualité à de nouveaux acteurs, plus diversifiés. La seconde est le rôle accru de la demande dans la définition de la qualité qui induit le secteur privé à articuler la qualité au consommateur. Enfin la qualité se définit de plus en plus de manière procédurale. Ces trois évolutions accentuent la tension entre l’espace de formulation des exigences de qualité et l’espace de la définition technique de la qualité. Ces trois évolutions valent mutatis mutandis pour le secteur public et posent de manière critique le rôle de l’Etat. Pour dépasser cette tension entre espace de la formulation des exigences de qualité et espace de normalisation technique, l’action publique doit être capable de prendre simultanément en charge débat et expertise dans un processus qui relève plus de l'innovation que de seule normalisation. Unmodèle expérimentaliste de l'action publique est proposé pour répondre à ce défi.

  17. Codes et turbocodes

    CERN Document Server

    Berrou, Claude

    2007-01-01

    Cet ouvrage est consacré à l'une des fonctions essentielles des systèmes de télécommunications modernes : le codage de canal ou codage correcteur d'erreurs. À la croisée de la théorie de l'information, des mathématiques et de l'électronique, le codage de canal a connu de nombreux développements depuis les travaux fondateurs de Claude Shannon. Du simple code de Hamming (1950) aux récents turbocodes (1993) en passant par les codes LDPC (1962), le codage de canal a considérablement évolué et a intégré des concepts de plus en plus sophistiqués, en particulier le traitement probabiliste de l'inform

  18. Lipochimie et innovations

    Directory of Open Access Journals (Sweden)

    Alfos Carine

    2003-09-01

    Full Text Available Peut-on parler d’un nouvel âge d’or pour les produits à base de ressources végétales renouvelables et notamment pour les huiles ? Porteurs de performances spécifiques et de caractéristiques plus écologiquement correctes, leur emploi ouvre à l’industrie un potentiel d’innovations auquel participe le département de chimie et rhéologie de l’Iterg. La prise de conscience collective, associée aux évolutions des réglementations françaises et européennes, devrait conduire les industries à prendre de plus en plus en compte le respect de l’environnement dans leurs activités. La substitution de dérivés pétrochimiques par des produits d’origine agricole dans certains secteurs industriels (détergence, lubrifiants, solvants notamment contribue à la protection de notre environnement : diminution des volumes de déchets et des effluents, lutte contre l’effet de serre, moindre écotoxicité, innocuité pour la santé. De plus, l’épuisement latent des ressources pétrolières et la pratique de la jachère ont permis d’accélérer le développement de nouvelles voies de valorisations des huiles végétales et plus largement des agroressources. Les enjeux, à l’horizon 2010, sont bien plus importants encore pour ces produits, qui de part leur fonctionnalité spécifique, ont vocation à continuer d’occuper des marchés de niche. D’ici 10 ans, 2 à 3 millions d’hectares pourraient être consacrés à l’industrie du végétal \\; il s’agit là d’une véritable stratégie de développement durable qui nécessite un soutien politique, une vision à long terme et une motivation forte de l’industrie.

  19. Electronique et optoélectronique organiques

    CERN Document Server

    Moliton, Andre

    2011-01-01

    Ce livre expose les bases de l lectronique organique, aussi dite plastique ou souple, par opposition l lectronique conventionnelle. Il pr sente les bases th oriques physico-chimiques de ce domaine: th orie des mat riaux unidimensionnels; th orie des semiconducteurs organiques; d localisation possible des lectrons dans ces mat riaux et leur bande d absorption/ mission, etc. Il d crit d autre part les divers composants lectroniques/opto lectroniques auxquels ces mat riaux organiques ont pu donner naissance et qui sont actuellement commercialis?'s (ou pr ts l tre) tels que: les crans angles de vu

  20. Arktis - et internationalt anliggende?

    DEFF Research Database (Denmark)

    Mouyal, Lone Wandahl

    2015-01-01

    De fem arktiske kyststater; USA, Canada, Norge, Danmark (via Grønland) og Rusland har de senest år politisk tilkendegivet at reguleringen af det arktiske område skal ske på regional basis. Imidlertid vokser presset fra international side om, at Arktis er et international anliggende, man må samarbejde om – også når det gælder regulering. I kronikken i Jyllandsposten giver forfatteren udtryk for, at Danmark fremadrettet må betragte Arktis som et fællesanliggende for det internationale samfund, således at reguleringen i stigende grad må forventes at flytte fra nationalt og regionalt regi til den internationale sfære.