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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. 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 ...

  4. 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.

  5. 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.

  6. 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.

  7. 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 ...

  8. 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

  9. 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

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

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

    2002-01-01

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

  11. 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

  12. Changes in the Common Bean Transcriptome in Response to Secreted and Surface Signal Molecules of Rhizobium etli1[OPEN

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

    2015-01-01

    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

  13. 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.

  14. 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 ...

  15. 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 ...

  16. 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.

  17. 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

  18. 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.

    1992-01-01

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

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

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

    2013-09-01

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

  20. Regulation of tryptophan genes in Rhizobium leguminosarum.

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    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...

  1. 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.

  2. 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

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    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.

  3. 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.

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    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 BLR27T?=?LMG 28441T?=?DSM 29286T), Rhizobium bangladeshense sp. nov. (type strain BLR175T?=?LMG 28442T?=?DSM 29287T) and Rhizobium binae sp. nov. (type strain BLR195T?=?LMG 28443T?=?DSM 29288T), are proposed. These species share common nodulation genes (nodA, nodC and nodD) that are similar to those of the symbiovar viciae. PMID:26060217

  4. 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.

  5. Tryptophan auxotrophs of Rhizobium japonicum.

    OpenAIRE

    Wells, S E; Kuykendall, L D

    1983-01-01

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

  6. Rhizobium pusense is the main human pathogen in the genus Agrobacterium/Rhizobium.

    Science.gov (United States)

    Aujoulat, F; Marchandin, H; Zorgniotti, I; Masnou, A; Jumas-Bilak, E

    2015-05-01

    Rhizobium pusense was recently described after isolation from the rhizosphere of chickpea. Multilocus sequence-based analysis of clinical isolates identified as Agrobacterium (Rhizobium) radiobacter demonstrated that R. pusense is the main human pathogen within Agrobacterium (Rhizobium) spp. Clinical microbiology of Agrobacterium (Rhizobium) should be considered in the light of recent taxonomic changes. PMID:25669878

  7. 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...

  8. 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

  9. 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

  10. 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

  11. 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

  12. 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...

  13. Rhizobium metallidurans sp. nov., a symbiotic heavy metal resistant bacterium isolated from the Anthyllis vulneraria Zn-hyperaccumulator.

    Science.gov (United States)

    Grison, Claire M; Jackson, Stephen; Merlot, Sylvain; Dobson, Alan; Grison, Claude

    2015-05-01

    A Gram-stain-negative, aerobic, rod-shaped, non-spore-forming bacterium (ChimEc512(T)) was isolated from 56 host seedlings of the hyperaccumulating Anthyllis vulneraria legume, which was on an old zinc mining site at Les Avinières, Saint-Laurent-Le-Minier, Gard, South of France. On the basis of 16S rRNA gene sequence similarities, strain ChimEc512(T) was shown to belong to the genus Rhizobium and to be most closely related to Rhizobium endophyticum CCGE 2052(T) (98.4%), Rhizobium tibeticum CCBAU 85039(T) (98.1%), Rhizobium grahamii CCGE 502(T) (98.0%) and Rhizobium mesoamericanum CCGE 501(T) (98.0%). The phylogenetic relationships of ChimEc512(T) were confirmed by sequencing and analyses of recA and atpD genes. DNA-DNA relatedness values of strain ChimEc512(T) with R. endophyticum CCGE 2052(T), R. tibeticum CCBAU 85039(T), R. mesoamericanum CCGE 52(T), Rhizobium grahamii CCGE 502(T), Rhizobium etli CCBAU 85039(T) and Rhizobium radiobacter KL09-16-8-2(T) were 27, 22, 16, 18, 19 and 11%, respectively. The DNA G+C content of strain ChimEc512(T) was 58.9 mol%. The major cellular fatty acid was C18 : 1?7c, characteristic of the genus Rhizobium . The polar lipid profile included phosphatidylethanolamine, phosphatidylmonomethylethanolamine, phosphatidylglycerol and phosphatidylcholine and moderate amounts of aminolipids, phospholipid and sulfoquinovosyl diacylglycerol. Although ChimEc512(T) was able to nodulate A. vulneraria, the nodC and nifH genes were not detected by PCR. The rhizobial strain was tolerant to high concentrations of heavy metals: up to 35 mM Zn and up to 0.5 mM Cd and its growth kinetics was not impacted by Zn. The results of DNA-DNA hybridizations and physiological tests allowed genotypic and phenotypic differentiation of strain ChimEc512(T) from species of the genus Rhizobium with validly published names. Strain ChimEc512(T), therefore, represents a novel species, for which the name Rhizobium metallidurans sp. nov. is proposed, with the type strain ChimEc512(T) (?=DSM 26575 = CIP 110550(T)). PMID:25701848

  14. 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

  15. 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.

  16. : 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...

  17. 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.

  18. 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....

  19. Effects of Temperature Stress on Bean-Nodulating Rhizobium Strains

    OpenAIRE

    Michiels, Jan; Verreth, Christel; Vanderleyden, Jos

    1994-01-01

    High soil temperatures in tropical areas limit nodulation and dinitrogen fixation by strains of Rhizobium. Several heat-tolerant bean-nodulating Rhizobium strains have been isolated previously. However, the basis of their resistance to heat remains unknown. In this study, we compared the effects of heat on symbiotic nitrogen fixation, cell survival, amino acid uptake, and protein synthesis in a heat-tolerant (CIAT899) and a heat-sensitive (CNPAF512) bean-nodulating Rhizobium strain. Acetylene...

  20. Recognition of Leguminous Hosts by a Promiscuous Rhizobium Strain

    OpenAIRE

    Shantharam, S; Wong, Peter P.

    1982-01-01

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

  1. Identification and manipulation of Rhizobium phytohormone genes

    Energy Technology Data Exchange (ETDEWEB)

    Ditta, G.S.

    1988-06-27

    The goal of this project was to determine whether phytohormone production by the gram-negative bacterium Rhizobium meliloti is required for successful modulation and symbiosis with alfalfa. specifically, we undertook the study of indoleacetic acid (IAA; auxin) production by R. meliloti and sought to create a mutant totally deficient in IAA biosynthesis. For many years it has been known that rhizobia are capable of synthesizing and excreting IAA, and it has often been suggested that this could be of importance for the initiation of root nodule development. Published work demonstrating the involvement of bacterial IAA genes in pathogenesis by Pseudomonas syringae and Agrobacterium tumefaciens further emphasized the need for this type of study in Rhizobium.

  2. 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...

  3. 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...

  4. Biodegradation of Phosphonomycin by Rhizobium huakuii PMY1

    OpenAIRE

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

    1998-01-01

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

  5. 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 (?related species). PEL4 strains also differed from related species based on multilocus sequence analysis of three housekeeping genes (glnII, gyrB and recA). Nucleotide identities of the three concatenated genes between PEL4 strains and related species ranged from 91.8 to 94.2?%, being highest with Rhizobium fabae. DNA-DNA hybridization (?Rhizobium ecuadorense sp. nov. The type strain is CNPSo 671T (?=?UMR 1450T?=?PIMAMPIRS I 5T?=?LMG 27578T). PMID:26297041

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

    OpenAIRE

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

    1981-01-01

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

  7. 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...

  8. 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...

  9. 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...

  10. 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...

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

    OpenAIRE

    Fuchs, R L; Keister, D L

    1980-01-01

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

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

    OpenAIRE

    Napoli, C.; Albersheim, P.

    1980-01-01

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

  13. 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.

  14. 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...

  15. Reiterated DNA sequences in Rhizobium and Agrobacterium spp.

    OpenAIRE

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

    1987-01-01

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

  16. 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...

  17. 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.

  18. 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.

  19. 75 FR 5120 - United States, et al. v. Stericycle, Inc., et al.; Proposed Final Judgment and Competitive Impact...

    Science.gov (United States)

    2010-02-01

    ... autoclave in Newton, Kansas; transfer stations in Kansas City, Kansas; Oklahoma City, Oklahoma; Omaha... entry of this Final Judgment without trial or adjudication of any issue of fact or law; and without this Final Judgment constituting any evidence against or admission by any party regarding any issue of law...

  20. 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

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

    OpenAIRE

    MERCAN, Nazime

    2002-01-01

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

  2. 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.

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

    OpenAIRE

    Ademir Sérgio Ferreira de Araújo; Ricardo Silva Araújo

    2006-01-01

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

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

    DEFF Research Database (Denmark)

    Jensen, Erik Steen; SØrensen, Lasse Holst

    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 under aseptic conditions. Five types differing in isoenzyme composition pattern were found among 15 isolates from 'Afghanistan' nodules. None were identical with 'Tom' strain from Turkey, which also forms effective nodules with 'Afghanistan'. The five types were also different with respect to isoenzyme pattern with Rhizobium leguminosarum strains isolated from a modern pea variety cultivated in the same field.

  5. 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...

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

    OpenAIRE

    Archana, G; Desai, Dhwani K.; Falguni R. Joshi; Anjana J. Desai

    2009-01-01

    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 ...

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

    OpenAIRE

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

    1995-01-01

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

  8. 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...

  9. 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...

  10. 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...

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

    OpenAIRE

    Toro, Nicolas; Olivares, José

    1986-01-01

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

  12. Rhizobium alvei sp. nov., isolated from a freshwater river.

    Science.gov (United States)

    Sheu, Shih-Yi; Huang, Hsing-Wei; Young, Chiu-Chung; Chen, Wen-Ming

    2015-02-01

    A bacterial strain designated TNR-22(T) was isolated from a freshwater river in Taiwan and characterized using a polyphasic taxonomic approach. Cells of strain TNR-22(T) were facultatively anaerobic, Gram-stain-negative, rod-shaped, motile by a single polar flagellum and formed cream-coloured colonies. Growth occurred at 4-45 °C (optimum, 25-30 °C), with 0-1.0 % (w/v) NaCl (optimum, 0.5 %) and at pH 7.0-8.0 (optimum, pH 7.0). Strain TNR-22(T) did not form nodules on Macroptilium atropurpureum. The nifH gene encoding denitrogenase reductase was not detected by PCR. The major fatty acids (>10 %) of strain TNR-22(T) were C18 : 1?7c and C16 : 0. The DNA G+C content was 60.3 mol%. The polar lipid profile consisted of a mixture of phosphatidylethanolamine, phosphatidylglycerol, phosphatidylcholine, diphosphatidylglycerol, an uncharacterized aminoglycolipid and an uncharacterized phospholipid. Comparative analysis of 16S rRNA gene sequences showed that strain TNR-22(T) constituted a distinct branch within the genus Rhizobium, showing the highest level of sequence similarity with Rhizobium rosettiformans W3(T) (96.3 %). Phenotypic characteristics of the novel strain also differed from those of the most closely related species of the genus Rhizobium. On the basis of the genotypic, chemotaxonomic and phenotypic data, strain TNR-22(T) represents a novel species in the genus Rhizobium, for which the name Rhizobium alvei sp. nov. is proposed. The type strain is TNR-22(T) (?= BCRC 80408(T)?= LMG 26895(T)?= KCTC 23919(T)). PMID:25385988

  13. 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

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

    OpenAIRE

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

    2012-01-01

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

  15. 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.

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

    OpenAIRE

    Maria G?owacka; Agnieszka St?pie?; Sylwia Szyprowska

    1996-01-01

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

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

    OpenAIRE

    Araújo Ademir Sérgio Ferreira de; Araújo Ricardo Silva

    2006-01-01

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

  18. 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...

  19. 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...

  20. 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

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

    OpenAIRE

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

    1980-01-01

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

  2. 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...

  3. Induced plasmid-genome rearrangements in Rhizobium japonicum.

    OpenAIRE

    Berry, J O; Atherly, A G

    1984-01-01

    The P group resistance plasmids RP1 and RP4 were introduced into Rhizobium japonicum by polyethylene-glycol-induced transformation of spheroplasts. After cell wall regeneration, transformants were recovered by selecting for plasmid determinants. Plant nodulation, nitrogen fixation, serological, and bacterial genetics studies revealed that the transformants were derived from the parental strains and possessed the introduced plasmid genetic markers. Agarose gel electrophoresis, restriction enzy...

  4. Evaluation of Nitrate Reductase Activity in Rhizobium japonicum†

    OpenAIRE

    Streeter, John G.; DeVine, Paul J.

    1983-01-01

    Nitrate reductase activity was evaluated by four approaches, using four strains of Rhizobium japonicum and 11 chlorate-resistant mutants of the four strains. It was concluded that in vitro assays with bacteria or bacteroids provide the most simple and reliable assessment of the presence or absence of nitrate reductase. Nitrite reductase activity with methyl viologen and dithionite was found, but the enzyme activity does not confound the assay of nitrate reductase.

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

    OpenAIRE

    Sessitsch, A

    1997-01-01

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

  6. 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...

  7. 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 under aseptic conditions. Five types differing in isoenzyme composition pattern were found among 15 isolates from 'Afghanistan' nodules. None were identical with 'Tom' strain from Turkey, which also form...

  8. Organization and expression of Rhizobium meliloti nitrogen fixation genes

    OpenAIRE

    Corbin, David; Barran, Leslie; Ditta, Gary

    1983-01-01

    The boundaries of a nif gene cluster in Rhizobium meliloti were determined by Tn5 mutagenesis. These genes are clustered within a 14- to 15-kilobase (kb) region that includes the nitrogenase structural genes. Sequences within 10 kb on either side of this region are devoid of symbiotically essential gene function. RNA blot analysis identified a 5- to 6-kb transcript that corresponds to the nitrogenase structural gene operon. The 5? end of this transcript and its polarity were determined by nuc...

  9. 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...

  10. 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

  11. 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

  12. 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...

  13. 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....

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

    Science.gov (United States)

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

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

    OpenAIRE

    Kaluza, K.; Fuhrmann, M. (Manfred); HAHN, M; Regensburger, B; Hennecke, H.

    1983-01-01

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

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

    OpenAIRE

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

    1985-01-01

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

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

    OpenAIRE

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

    1984-01-01

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

  18. 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.)

  19. 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-...

  20. Rhizobium lusitanum sp. nov. a bacterium that nodulates Phaseolus vulgaris.

    Science.gov (United States)

    Valverde, Angel; Igual, José M; Peix, Alvaro; Cervantes, Emilio; Velázquez, Encarna

    2006-11-01

    The species Phaseolus vulgaris is a promiscuous legume nodulated by several species of the family Rhizobiaceae. During a study of rhizobia nodulating this legume in Portugal, we isolated several strains that nodulate P. vulgaris effectively and also Macroptilium atropurpureum and Leucaena leucocephala, but they form ineffective nodules in Medicago sativa. According to phylogenetic analysis of the 16S rRNA gene sequence, the strains from this study belong to the genus Rhizobium, with Rhizobium rhizogenes and Rhizobium tropici as the closest related species, with 99.9 and 99.2% similarity, respectively, between the type strains of these species and strain P1-7T. The nodD and nifH genes carried by strain P1-7T are phylogenetically related to those of other species nodulating Phaseolus. This strain does not carry virulence genes present in the type strain of R. rhizogenes, ATCC 11325T. Analysis of the recA and atpD genes confirms this phylogenetic arrangement, showing low similarity with respect to those of R. rhizogenes ATCC 11325T (91.9 and 94.1% similarity, respectively) and R. tropici IIB CIAT 899T (90.6% and 91.8% similarity, respectively). The intergenic spacer (ITS) of the strains from this study is phylogenetically divergent from those of R. rhizogenes ATCC 11235T and R. tropici CIAT 899T, with 85.9 and 82.8% similarity, respectively, with respect to strain P1-7T. The tRNA profile and two-primer random amplified polymorphic DNA pattern of strain P1-7T are also different from those of R. rhizogenes ATCC 11235T and R. tropici CIAT 899T. The strains isolated in this study can be also differentiated from R. rhizogenes and R. tropici by several phenotypic characteristics. The results of DNA-DNA hybridization showed means of 28 and 25% similarity between strain P1-7T and R. rhizogenes ATCC 11235T and R. tropici CIAT 899T, respectively. All these data showed that the strains isolated in this study belong to a novel species of the genus Rhizobium, for which we propose the name Rhizobium lusitanum sp. nov.; the type strain is P1-7T (=LMG 22705T=CECT 7016T). PMID:17082403

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

    Science.gov (United States)

    Marvel, D J; Kuldau, G; Hirsch, A; Richards, E; Torrey, J G; Ausubel, F M

    1985-09-01

    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 and point mutations in three contiguous nodulation genes (nodABC) of Rhizobium meliloti, the endosymbiont of alfalfa (Medicago sativa). The complemented R. meliloti nod mutants induced effective nitrogen-fixing nodules on alfalfa seedlings but not on siratro, cowpeas, or Parasponia. The cloned RP501 nodulation locus hybridized to DNA fragments carrying the R. meliloti nodABC genes. A 3-kb cluster of Tn5 insertion mutations on the RP501 13.4-kb EcoRI fragment prevented complementation of R. meliloti nodABC mutations. PMID:16593600

  2. 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)

  3. 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...

  4. 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 ...

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

    OpenAIRE

    Selvaraj, G.; Iyer, V N

    1983-01-01

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

  6. 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.

  7. 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.

  8. 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

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

    OpenAIRE

    Crawford, S. L.; Berryhill, D L

    1983-01-01

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

  10. 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

  11. 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.

  12. Rhizobium tropici teu genes involved in specific uptake of Phaseolus vulgaris bean-exudate compounds.

    Science.gov (United States)

    Rosenblueth, M; Hynes, M F; Martínez-Romero, E

    1998-06-01

    Rhizobium tropici nodulates and fixes nitrogen in bean. In the R. tropici strain CFN299 we identified and characterized teu genes (tropici exudate uptake) induced by bean root exudates, localized by insertion of a promoter-less Tn5-gusA1 transposon. teu genes are present on a plasmid of around 185 kb that is conserved in all R. tropici strains. Proteins encoded by teu genes show similarity to ABC transporters, specifically to ribose transport proteins. No induction of the teu genes was obtained by treatment with root exudates from any of several other plants tested, with the exception of Macroptilium atropurpureum, which is also a host plant for R. tropici. It appears that the inducing compound is characteristic of bean and closely related legumes. It is present in root exudates, but not in seeds. This compound is removed, presumably by metabolism, from the exudates by the majority of bean-nodulating rhizobia (such as R. etli, R. leguminosarum bv. phaseoli and R. giardinii). The principal inducing compound has not been identified, but some induction was obtained using trigonelline. The CFN299 strain seems to have an additional uptake system, as no phenotype is observed in two different mutants. R. tropici strain CIAT899, on the other hand, must have only one uptake system, since a mutant bearing an insertion in the teu genes could not remove the compound from the exudates as efficiently as the wild type, and it showed diminished nodulation competitiveness. PMID:9671027

  13. 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.

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

    OpenAIRE

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

    1989-01-01

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

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

    OpenAIRE

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

    1980-01-01

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

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

    OpenAIRE

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

    2013-01-01

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

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

    OpenAIRE

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

    1985-01-01

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

  18. 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...

  19. 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-conte...

  20. 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...

  1. 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.

  2. 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...

  3. 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.

  4. 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

  5. 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 dehydrogenase (EC 1.1.1.30), mannitol dehydrogenase (EC 1.1.1.67), and arabinose dehydrogenase (EC 1.1.1.46). It was possible to distinguish at least 7 different types of pea rhizobia among 16 strains isolated from one batch of 5 kg soil.

  6. 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.

  7. 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

  8. 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...

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

    OpenAIRE

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

    2015-01-01

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

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

    OpenAIRE

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

    2012-01-01

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

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

    Science.gov (United States)

    Tang, Wen-Juan; Zhou, Ying; Ye, Bang-Ce

    2015-01-01

    Rhizobium sp. LMB-1, newly isolated from greenhouse soil, can effectively degrade phthalate. Here, we present a 5.2-Mb assembly of this Rhizobium sp. genome for the first time. It may provide abundant molecular information for the transformation of phthalates. PMID:25953182

  12. 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 ZYY136T 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 ZYY136T and ZYY9 showed the highest similarity, of 97.0??%, to Rhizobium tarimense PL-41T. 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 ZYY136T and ZYY9 was 82.3??%, and ZYY136T showed 34.0??% DNA-DNA relatedness with the most closely related type strain, R. tarimense PL-41T. The DNA G+C content of strain ZYY136T 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 ZYY136T and ZYY9 could be differentiated from the previously defined species of the genus Rhizobium by several phenotypic characteristics. Therefore, we conclude that strains ZYY136T and ZYY9 represent a novel species of the genus Rhizobium, for which the name Rhizobium oryzicola sp. nov. is proposed (type strain ZYY136T?=?ACCC 05753T?=?KCTC 32088T). PMID:26016492

  13. 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...

  14. 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...

  15. [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

  16. 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

  17. 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)

  18. 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.

  19. 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.

  20. 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.

  1. 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

  2. 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)

  3. 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)

  4. 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.

  5. 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

    Effects of salt stress in hydroponic media on clover plants inoculated with Rhizobium. The application of salt stress in hydroponic conditions on clover seedlings (Trifolium alexandrinum L.) inoculated with Rhizobium affected the nodulation starting from 2 g NaCl?$\\cdot$?l$^{-1}$, whereas the growth began to be reduced only from 4 g?$\\cdot$?l$^{-1}$. The growth of shoots was reduced by about 20% at 4 g?$\\cdot$?l$^{-1}$ and 44% at 6 g?$\\cdot$?l$^{-1}$. The development of the root system was le...

  6. 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

  7. 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

    Scientific Electronic Library Online (English)

    Tehuni Orlando, González; João Carlos, Campanharo; Eliana Gertrudes de Macedo, Lemos.

    2008-09-01

    Full Text Available 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 acas [...] o, 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. Abstract in english 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 greenho [...] use 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.

  8. 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...

  9. Genome of Rhizobium sp. UR51a, Isolated from Rice Cropped in Southern Brazilian Fields.

    Science.gov (United States)

    de Souza, Rocheli; Sant'Anna, Fernando Hayashi; Ambrosini, Adriana; Tadra-Sfeir, Michele; Faoro, Helisson; Pedrosa, Fabio Oliveira; Souza, Emanuel Maltempi; Passaglia, Luciane M P

    2015-01-01

    Rhizobium sp. UR51a is a Gram-negative bacterium isolated from roots of rice plants, and it presents plant growth-promoting abilities. The nutrient uptake in rice plants inoculated with UR51a was satisfactory. The genome of strain UR51a is composed of 5,233,443-bp and harbors 5,079 coding sequences. PMID:25838497

  10. 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...

  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 23252T 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 23252T (?=?CGMCC 1.12621T?=?LMG 27729T) 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. 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

  13. 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

  14. 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

  15. 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.

  16. 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.

  17. 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...

  18. 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...

  19. 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.

  20. 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. ...

  1. 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 ...

  2. 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... broiler processing complex and related assets. George's and Tyson are competing chicken processors, each... of a Harrisonburg, Virginia chicken processing complex (``the Transaction'') from Tyson Foods,...

  3. 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...

  4. 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.

  5. 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.

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

    OpenAIRE

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

    1986-01-01

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

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

    Science.gov (United States)

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

    2012-01-01

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

  8. 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)

  9. 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.

  10. 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)

  11. 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.

  12. 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.

  13. In vitro expression of nitrogenase activity in Parasponia-Rhizobium strain ANU 289.

    Science.gov (United States)

    Mohapatra, S S; Bender, G L; Shine, J; Rolfe, B G; Gresshoff, P M

    1983-01-01

    Rhizobium strain ANU 289 derepressed nitrogenase activity under defined in vitro conditions. Acetylene reduction was detected both in agar and liquid stationary culture. The strain is capable of nitrogen-fixing nodulation of legumes [such as siratro (Macroptilium atropurpureum Urb] as well as the non-legumes Parasponia andersonii and P. rugosa. Nitrogenase activity as high as 40-70 nmol C2H4 per mg protein after 7 days of incubation was detected. Strain ANU 289 was similar to Rhizobium strains 32 H1 and CB 756 with regard to oxygen requirement in the gas phase for development of nitrogenase activity between 0 and 10% O2, but showed increased sensitivity to oxygen repression at 20% O2. Strain ANU 289 also showed pronounced sensitivity to exogenous glutamine compared to strains 32 H1 and CB 756. PMID:6575732

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

    OpenAIRE

    Kingsley, Mark T.; Bohlool, B. Ben

    1981-01-01

    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 andep...

  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. 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...

  17. 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, ...

  18. 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...

  19. 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...

  20. 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...

  1. 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.

  2. 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...

  3. Rhizobium meliloti swims by unidirectional, intermittent rotation of right-handed flagellar helices.

    OpenAIRE

    Götz, R.; Schmitt, R

    1987-01-01

    The 5 to 10 peritrichously inserted complex flagella of Rhizobium meliloti MVII-1 were found to form right-handed flagellar bundles. Bacteria swam at speeds up to 60 microns/s, their random three-dimensional walk consisting of straight runs and quick directional changes (turns) without the vigorous angular motion (tumbling) seen in swimming Escherichia coli cells. Observations of R. meliloti cells tethered by a single flagellar filament revealed that flagellar rotation was exclusively clockwi...

  4. 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)

  5. 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...

  6. 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...

  7. 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 ...

  8. 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. ...

  9. 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...

  10. 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...

  11. 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 ...

  12. Foliar Chlorosis in Symbiotic Host and Nonhost Plants Induced by Rhizobium tropici Type B Strains

    OpenAIRE

    O'Connell, Kevin P.; Handelsman, Jo

    1993-01-01

    Rhizobium tropici CIAT899 induced chlorosis in the leaves of its symbiotic hosts, common bean (Phaseolus vulgaris L.), siratro (Macroptilium atropurpureum Urb.), and Leucaena leucocephala (Lam.) de Wit. Chlorosis induction by strains CIAT899 and CT9005, an exopolysaccharide-deficient mutant of CIAT899, required carbon substrate. When the bacteria were added at planting in a solution of mannitol (50 g/liter), as few as 103 cells of CIAT899 were sufficient to induce chlorosis in bean plants. Al...

  13. 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...

  14. 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...

  15. 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.

  16. In vitro sensitivity of Rhizobium and phosphate solubilising bacteria to herbicides.

    Science.gov (United States)

    Jeenie; Sharma, Poonam; Khanna, Veena

    2011-06-01

    Nitrogen fixing bacteria, rhizobia and phosphate solubilizing bacteria (PSB) are the commonly applied microbial inoculants in grain legumes (Pulses). It is important to apply herbicides to control weeds in order to augment yield of the crop. The herbicides may however, be incompatible with the microbial inoculants. This study compared the effect of the recommended pre-plant incorporated herbicide, fluchloralin (20.25 × 10(4) ppm) and pre-emergence herbicide, pendimethalin in two doses (9 × 10(4) and 15 × 10(4) ppm) on the growth and survival of mungbean Rhizobium and PSB, under laboratory conditions. These herbicides were also used under field conditions in conjunction with biofertilizers (R, PSB) to improve grain yield of mungbean. It was found that fluchloralin (20.25 × 10(4) ppm) and the lower dose of pendimethalin (9 × 10(4) ppm) had no adverse effect on growth of Rhizobium and PSB. The higher dose of pendimethalin (15 × 10(4) ppm) was safe on PSB but it imposed a retarding effect on the growth of Rhizobium. PMID:22654170

  17. Rhizobium capsici sp. nov., isolated from root tumor of a green bell pepper (Capsicum annuum var. grossum) plant.

    Science.gov (United States)

    Lin, Shih-Yao; Hung, Mei-Hua; Hameed, Asif; Liu, You-Cheng; Hsu, Yi-Han; Wen, Cheng-Zhe; Arun, A B; Busse, Hans-Jürgen; Glaeser, Stefanie P; Kämpfer, Peter; Young, Chiu-Chung

    2015-03-01

    A novel, Gram-staining-negative, rod-shaped, aerobic and motile bacterium, designated strain CC-SKC2(T), was isolated from the root tumor of a green bell pepper (Capsicum annuum var. grossum) plant in Taiwan. Cells were positive for oxidase and catalase activities and exhibited growth at 25-37 °C, pH 4.0-9.0 and tolerated NaCl concentrations up to 4.0 % (w/v). Strain CC-SKC2(T) is able to trigger nodulation in soybean (Glycine max Merr.), but not in Capsicum annuum var. grossum, red bean (Vigna angularis), sesbania (Sesbania roxburghii Merr.) or alfalfa (Medicago varia Martin.). The novel strain shared highest 16S rRNA gene sequence similarity to Rhizobium rhizoryzae KCTC 23652(T) and Rhizobium straminoryzae CC-LY845(T) (both 97.5 %) followed by Rhizobium lemnae L6-16(T) (97.3 %), Rhizobium pseudoryzae KCTC 23294(T) (97.1 %), and Rhizobium paknamense NBRC 109338(T) (97.0 %), whereas other Rhizobium species shared <96.7 % similarity. The DNA-DNA relatedness values of strain CC-SKC2(T) with R. rhizoryzae KCTC 23652(T), R. pseudoryzae KCTC 23294(T) and R. paknamense NBRC 109338(T) were 11.4, 17.2 and 17.0 %, respectively (reciprocal values were 11.1, 28.3 and 24.0 %, respectively). Phylogenetic analysis based on 16S rRNA, atpD and recA genes revealed a distinct taxonomic position attained by strain CC-SKC2(T) with respect to other Rhizobium species. The major fatty acids in strain CC-SKC2(T) were C16:0, C19:0 cyclo ?8c, C14:0 3-OH and/or C16:1 iso I and C18:1 ?7c and/or C18:1 ?6c. The polyamine pattern showed predominance of spermidine and moderate amounts of sym-homospermidine. The predominant quinone system was ubiquinone (Q-10) and the DNA G+C content was 60.5 mol%. On the basis of polyphasic taxonomic evidence presented here, strain CC-SKC2(T) is proposed to represent a novel species within the genus Rhizobium, for which the name Rhizobium capsici sp. nov. is proposed. The type strain is CC-SKC2(T) (=BCRC 80699(T) = JCM 19535(T)). PMID:25555455

  18. 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

  19. 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.

  20. 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

  1. 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)

  2. 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)

  3. 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.)

  4. 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.

  5. 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)

  6. 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...

  7. 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)

  8. 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...

  9. 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.

  10. Rhizobium trifolii 0403 Is Capable of Growth in the Absence of Combined Nitrogen †

    OpenAIRE

    Urban, James E.; Davis, Lawrence C.; Brown, Susan J.

    1986-01-01

    Rhizobium trifolii 0403 was treated with 16.6 mM succinate and other nutrients and thereby induced to grow in nitrogen-free medium. The organism grew microaerophilically on either semisolid or liquid medium, fixing atmospheric nitrogen to meet metabolic needs. Nitrogen fixation was measured via 15N incorporation (18% 15N enrichment in 1.5 doublings) and acetylene reduction. Nitrogen-fixing cells had a Km for acetylene of 0.07 atm (ca. 7.09 kPa), required about 3% oxygen for optimum growth in ...

  11. 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

  12. 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...

  13. 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...

  14. 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. ...

  15. 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...

  16. 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.

  17. 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...

  18. 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.

  19. 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...

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

    DEFF Research Database (Denmark)

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

    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 same 13 different groups. The largest group was represented 7 times according to isoenzymes and 8 times according to RFLP. This fixed non-random association of plasmid and chromosomal genotypes is consistent with a clonal population structure; it indicates limited exchange of plasmids under natural conditions. Seventeen isolates of 11 groups were highly effective and 2 isolates in one group almost ineffective.

  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. 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+ ...

  3. 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...

  4. 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...

  5. 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...

  6. 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...

  7. Multiple Copies of nodD in Rhizobium tropici CIAT899 and BR816

    OpenAIRE

    van Rhijn, P. J.; Feys, B; Verreth, C.; J. Vanderleyden

    1993-01-01

    Rhizobium tropici strains are able to nodulate a wide range of host plants: Phaseolus vulgaris, Leucaena spp., and Macroptilium atropurpureum. We studied the nodD regulatory gene for nodulation of two R. tropici strains: CIAT899, the reference R. tropici type IIb strain, and BR816, a heat-tolerant strain isolated from Leucaena leucocephala. A survey revealed several nodD-hybridizing DNA regions in both strains: five distinct regions in CIAT899 and four distinct regions in BR816. Induction exp...

  8. 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

  9. 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) ...

  10. 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...

  11. Phenotypic expression of mutations in a wide-host-range R plasmid in Escherichia coli and Rhizobium meliloti.

    OpenAIRE

    Hooykaas, P J; den Dulk-Ras, H.; Schilperoort, R. A.

    1982-01-01

    Eight different derivatives of R plasmid RP1 with thermosensitive mutations affecting maintenance in Escherichia coli and Pseudomonas aeruginosa were introduce into Rhizobium meliloti. None of the plasmids showed a thermosensitive character in R. meliloti. On the other hand, a certain deletion mutation in RP1 was found to cause plasmid instability in rhizobia and agrobacteria, but not in E. coli.

  12. 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.

  13. 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…

  14. 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.

  15. 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)

  16. 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

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

    Science.gov (United States)

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

    2015-06-01

    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

  18. 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.

  19. 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.

  20. 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

  1. 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

  2. Biological activity of Rhizobium sp. NGR234 Nod-factors on Macroptilium atropurpureum.

    Science.gov (United States)

    Reli?, B; Talmont, F; Kopcinska, J; Golinowski, W; Promé, J C; Broughton, W J

    1993-01-01

    The broad host range of Rhizobium sp. NGR234 is based mainly on its ability to secrete a family of lipooligosaccharide Nod factors. To monitor Nod-factor purification, we used the small seeded legume Macroptilium atropurpureum, which responds evenly and consistently to Nod factors. At concentrations between approximately equal to 10(-11) M and 10(-9) M, this response takes the form of deformation of the root hairs. Higher concentrations (approximately equal to 10(-9) to 10(-7) M), provoked profound "shepherd's crook" type curling of the root hairs. Similar concentrations of Nod factors of Bradyrhizobium japonicum, Rhizobium leguminosarum, and R. meliloti also provoked marked curling of the root hairs, but the latter two species are unable to nodulate Macroptilium. On the other hand, plant hormones, hormone-like substances, inhibitors of hormone action, as well as substituents of Nod factors were without effect in this bioassay. We thus conclude that only Nod factors are capable of inducing shepherd's crook type curling of Macroptilium root hairs. Perturbations in the auxin-cytokinin balance induced "pseudo" nodulation on M. atropurpureum, as did NodNGR factors at concentrations between 10(-7) and 10(-6) M. Concomitant inoculation of Macroptilium with a NodABC- mutant of NGR234 and sulfated NodNGR factors (NodNGR[S]) gave rise to plants that slowly greened, showing that the NodNGR factors permitted entry of the Nod- mutant into the roots. PMID:8118058

  3. Multiple copies of nodD in Rhizobium tropici CIAT899 and BR816.

    Science.gov (United States)

    van Rhijn, P J; Feys, B; Verreth, C; Vanderleyden, J

    1993-01-01

    Rhizobium tropici strains are able to nodulate a wide range of host plants: Phaseolus vulgaris, Leucaena spp., and Macroptilium atropurpureum. We studied the nodD regulatory gene for nodulation of two R. tropici strains: CIAT899, the reference R. tropici type IIb strain, and BR816, a heat-tolerant strain isolated from Leucaena leucocephala. A survey revealed several nodD-hybridizing DNA regions in both strains: five distinct regions in CIAT899 and four distinct regions in BR816. Induction experiments of a nodABC-uidA fusion in combination with different nodD-hybridizing fragments in the presence of root exudates of the different hosts indicate that one particular nodD copy contributes to nodulation gene induction far more than any other nodD copy present. The nucleotide sequences of both nodD genes are reported here and show significant homology to those of the nodD genes of other rhizobia and a Bradyrhizobium strain. A dendrogram based on the protein sequences of 15 different NodD proteins shows that the R. tropici NodD proteins are linked most closely to each other and then to the NodD of Rhizobium phaseoli 8002. PMID:8419293

  4. Generation of Rhizobium strains with improved symbiotic properties by random DNA amplification (RDA)

    Science.gov (United States)

    Mavingui, P; Flores, M; Romero, D; Martínez-Romero, E; Palacios, R

    1997-06-01

    To select for bacterial strains with enhanced phenotypes, random fragments of a whole genome, or a defined region of the genome, are cloned in a nonreplicating vector. The resulting plasmids are integrated by recombination into the homologous DNA region of the original strain. Integration gives rise to a nontandem direct duplication of the corresponding DNA region separated by the vector moiety of the plasmid. Recombination between the direct repeats leads to tandem duplication and further amplification of the entire integrated DNA, including the vector. Bacteria harboring the amplified DNA are selected by increasing the dosage of an antibiotic corresponding to a resistance marker of the integrated vector. Pooled strains carrying amplifications are then challenged with a selective pressure for the desired phenotype. After repeated selection cycles, the most fit strains are isolated. We used this process, which we called random DNA amplification, to select Rhizobium strains with increased competitiveness for nodule formation. Derivatives containing randomly amplified DNA regions of the symbiotic plasmid of Rhizobium tropici CFN299 strain were generated. Pools of amplified strains were inoculated onto various tropical legumes. After several cycles of selection through plants, amplified derivatives showing an increased competitiveness for nodule formation with the leguminous plant Macroptilium atropurpureum were obtained. PMID:9181580

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

    Science.gov (United States)

    Marvel, D J; Torrey, J G; Ausubel, F M

    1987-03-01

    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 in the region of three evolutionarily conserved genes (nodA, nodB, and nodC) required for legume nodulation in several Rhizobium and Bradyrhizobium species. Assays of these mutant Rp501 strains on legume hosts and Parasponia seedlings established that nodABC are required for nodulation of legume and nonlegume hosts, indicating that nonlegumes and legumes can respond to the same bacterial signal(s). In addition, a strain carrying a Tn5 insertion adjacent to the nodABC genes vigorously nodulated Rp501 legume hosts but was incapable of nodulating Parasponia, possibly identifying a nonlegume-specific nodulation function. PMID:16593814

  6. 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.

  7. 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.

  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. Effect of Rhizobium sp. BARIRGm901 inoculation on nodulation, nitrogen fixation and yield of soybean (Glycine max) genotypes in gray terrace soil.

    Science.gov (United States)

    Alam, Faridul; Bhuiyan, M A H; Alam, Sadia Sabrina; Waghmode, Tatoba R; Kim, Pil Joo; Lee, Yong Bok

    2015-10-01

    Soybean plants require high amounts of nitrogen, which are mainly obtained from biological nitrogen fixation. A field experiment was conducted by soybean (Glycine max) genotypes, growing two varieties (Shohag and BARI Soybean6) and two advanced lines (MTD10 and BGM02026) of soybean with or without Rhizobium sp. BARIRGm901 inoculation. Soybean plants of all genotypes inoculated with Rhizobium sp. BARIRGm901 produced greater nodule numbers, nodule weight, shoot and root biomass, and plant height than non-inoculated plants. Similarly, inoculated plants showed enhanced activity of nitrogenase (NA) enzyme, contributing to higher nitrogen fixation and assimilation, compared to non-inoculated soybean plants in both years. Plants inoculated with Rhizobium sp. BARIRGm901 also showed higher pod, stover, and seed yield than non-inoculated plants. Therefore, Rhizobium sp. BARIRGm901 established an effective symbiotic relationship with a range of soybean genotypes and thus increased the nodulation, growth, and yield of soybean grown in gray terrace soils in Bangladesh. PMID:25996879

  10. 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.

  11. 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...

  12. 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 ...

  13. 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.

  14. Efeito residual da vinhaça na população autóctone de Rhizobium do solo Residual effects of sugar cane vinasse on indigenous Rhizobia

    Directory of Open Access Journals (Sweden)

    Eli Sidney Lopes

    1986-01-01

    Full Text Available A adição de vinhaça na cultura canavieira tem sido praticada em áreas próximas às usinas de cana. Seria de interesse a avaliação do efeito da vinhaça no Rhizobium presente no solo (autóctone, uma vez que leguminosas têm sido indicadas para cultivo intercalar com a cana. Um experimento foi conduzido em casa de vegetação, com o objetivo de verificar a influência da aplicação contínua, durante três anos, de concentrações crescentes de vinhaça (0, 100 e 1.000 m³/ha/ano, com intervalos de seis meses entre aplicações, na população autóctone de Rhizobium que nodula amendoim, soja, feijão e crotalária. Em cada cultura, foram usados controle com solo sem adição da vinhaça e um tratamento inoculado com uma estirpe de Rhizobium de conhecida eficiência, recomendada para a cultura. Uma análise do efeito de uma dose adicional de 1,5 ppm do herbicida 2,4-D no tratamento com 100 m³/ha/ano foi também efetuada. Apesar de os resultados serem variados entre as culturas, ocorreram efeitos da vinhaça sobre a população de Rhizobium, causando aumentos de nodulação na crotalária e diminuição no amendoim. Não foram observados efeitos na nodulação do feijoeiro em nenhum dos tratamentos com a vinhaça, nem na soja, que nodulou somente com a dose mais elevada, sugerindo que o Rhizobium japonicum no solo estudado estava presente em baixo número. O tratamento com herbicida mostrou tendência de favorecer a nodulação e, conseqüentemente, a fixação biológica de N2, medida através do N na planta.The addition of vinasse on sugar cane plantations nearby alcohol fermentation plants is a common practice. Legumes are recommended to be intercropped with sugar cane. A greenhouse experiment was carried out with the objective of verifying the influence of continuous application of vinasse (0; 100 and 1000 m³/ha/year at six month interval during three years on soil rhizobia which nodulate peanuts, soybeans, dry-beans and crotalaria. Controls without vinasse and with efficient Rhizobium sp. strain were maintained. The effect of 2,4 D application on the 100 m³ vinasse/ha treatment was also studied. Although results were variable and dependent on crop, the addition of vinasse influenced the rhizobia population, causing for instance, reductions on nodulation of peanuts and increases on that of crotalaria; no effects were observed either on drybeans or soybeans. Indigenous population of soybean Rhizobiun was inexpressive. The herbicide treatment showed tendency to favour nodulation and consequently N2 fixation.

  15. 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

  16. Characterization of heat resistant mutant strains of Rhizobium sp. [Cajanus] for growth, survival and symbiotic properties.

    Science.gov (United States)

    Nehra, Kiran; Yadav, Attar S; Sehrawat, Anita R; Vashishat, R K

    2007-12-01

    Fourteen heat resistant mutant strains were isolated from a wild-type strain (PP201, Nod(+) Fix(+)) of Rhizobium sp. (Cajanus) by giving it a heat shock of 43°C. These mutant strains showed a greater increase in optical density (O.D.) and a higher viable cell count in both rhizospheric and non-rhizospheric soil at high temperature. Symbiotic studies showed that pigeon pea plants inoculated with a few mutant strains had ineffective nodules (Nod(+) Fix(-)) under controlled temperature (43°C) conditions, but under natural high temperature (40-45°C) conditions, the host plants infected with all the mutant strains showed higher total shoot nitrogen than the plants inoculated with the parent strain. Four mutant strains (HR-3, HR-6, HR-10 and HR-12) were found to be highly efficient for all the symbiotic parameters, and thus have the potential to be used as bioinoculants in the North-Western regions of India during the summer season. PMID:23100686

  17. 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.

  18. 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

  19. Interacción de Tsukamurella paurometabola C-924 con Rhizobium leguminosarum biovar phaseoli CFH en el cultivo de frijol / Interaction among Tsukamurella paurometabola C-924 and Rhizobium leguminosarum biovar phaseoli CFH in bean plants

    Scientific Electronic Library Online (English)

    Marieta, Marín Bruzos; Jesús, Mena Campos; Pavel, Chaveli Chávez; Rolando, Morán Valdivia; Eulogio, Pimentel Vázquez.

    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 Abstract in english The experiment was carried out to evaluate the interaction between Tsukamurella paurometabola C-924 and Rhizobium leguminosarum biovar phaseoli CFH in bean plants. Treatments consisted of non-inoculated plants (control), plants inoculated with T. paurometabola C-924, inoculated with R. leguminosarum [...] biovar phaseoli CFH and inoculated with both strains. The application of the microorganisms single or in coinoculation improved the germination of seeds. T. paurometabola C-924 did not enhanced Rhizobium nodulation. However, no significant differences were found among treatments for shoot height and diameter. There was an increase in number of leaves in the plants inoculated with T. paurometabola C-924. We concluded that the interaction between T. paurometabola C-924 and R. leguminosarum biovar phaseoli CFH improved the number of leaves and the germination of seeds and even though T. paurometabola C-924 did not enhance nodulation, this fact did not affect the plants growth.

  20. 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.

  1. 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

  2. Sulfation of nod factors via nodHPQ is nodD independent in Rhizobium tropici CIAT899.

    Science.gov (United States)

    Folch-Mallol, J L; Manyani, H; Marroquí, S; Sousa, C; Vargas, C; Nava, N; Colmenero-Flores, J M; Quinto, C; Megías, M

    1998-10-01

    A cosmid from the Rhizobium tropici CIAT899 symbiotic plasmid, containing most of the nodulation genes described in this strain, has been isolated. Although this cosmid does not carry a nodD gene, it confers ability to heterologous Rhizobium spp. to nodulate R. tropici hosts (Phaseolus vulgaris, Macroptilium atropurpureum, and Leucaena leucocephala). The observed phenotype is due to constitutive expression of the nodABCSUIJ operon, which has lost its regulatory region and is expressed from a promoter present in the cloning vector. Thin-layer chromatography (TLC) analysis of the Nod factors produced by this construction shows that it is still capable of synthesizing sulfated compounds, suggesting that the nodHPQ genes are organized as an operon that is transcribed in a nodD-independent manner and is not regulated by flavonoids. PMID:9768515

  3. 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...

  4. Transcriptomic analysis of Rhizobium leguminosarum biovar viciae in symbiosis with host plants Pisum sativum and Vicia cracca.

    OpenAIRE

    Karunakaran, R.; Ramachandran, VK; Seaman, JC; East, AK; Mouhsine, B; Mauchline, TH; Prell, J; Skeffington, A.; Poole, PS

    2009-01-01

    Rhizobium leguminosarum bv. viciae forms nitrogen-fixing nodules on several legumes, including pea (Pisum sativum) and vetch (Vicia cracca), and has been widely used as a model to study nodule biochemistry. To understand the complex biochemical and developmental changes undergone by R. leguminosarum bv. viciae during bacteroid development, microarray experiments were first performed with cultured bacteria grown on a variety of carbon substrates (glucose, pyruvate, succinate, inositol, acetate...

  5. Modulation of Metabolism and Switching to Biofilm Prevail over Exopolysaccharide Production in the Response of Rhizobium alamii to Cadmium

    OpenAIRE

    Schue, Mathieu; Fekete, Agnes; Ortet, Philippe; Brutesco, Catherine; Heulin, Thierry; Schmitt-Kopplin, Philippe; Achouak, Wafa; Santaella, Catherine

    2011-01-01

    Heavy metals such as cadmium (Cd2+) affect microbial metabolic processes. Consequently, bacteria adapt by adjusting their cellular machinery. We have investigated the dose-dependent growth effects of Cd2+ on Rhizobium alamii, an exopolysaccharide (EPS)-producing bacterium that forms a biofilm on plant roots. Adsorption isotherms show that the EPS of R. alamii binds cadmium in competition with calcium. A metabonomics approach based on ion cyclotron resonance Fourier transform mass spectrometry...

  6. 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...

  7. 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...

  8. 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

  9. 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...

  10. 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 ...

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

    OpenAIRE

    Perotto, S; Bonfante, P; Balestrini, R.; Andreotti, S.; Bianciotto, V

    2009-01-01

    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 aff...

  12. STUDY OF INTERACTIVE EFFECT OF RHIZOBIUM, AZOTOBACTER AND TRICHODERMA ALONE AND IN COMBINATION ON TRIGONELLA FOENUM-GRACEUM L

    OpenAIRE

    PATIL .V.A

    2013-01-01

    Trigonella foenum-graceum L. has unique ability to maintain a high protein level throughout the growing season therefore it is cultivated as a commercial crop. The use of biofertilizers on Trigonella plant showed the significant effect on growth and leaf, seed protein content. Compared to control shoot length and root length was more in the pot containing different biofertilizers. The total Chlorophyll content was maximum in the leaves of plants grown in the pot containing 50 gm of Rhizobium ...

  13. Two rhizobacterial strains, individually and in interactions with Rhizobium sp., enhance fusarial wilt control, growth, and yield in pigeon pea.

    Science.gov (United States)

    Dutta, Swarnalee; Morang, Pranjal; Kumar S, Nishanth; Dileep Kumar, B S

    2014-09-01

    A Pseudomonas aeruginosa strain, RRLJ 04, and a Bacillus cereus strain, BS 03, were tested both individually and in combination with a Rhizobium strain, RH 2, for their ability to enhance plant growth and nodulation in pigeon pea (Cajanus cajan L.) under gnotobiotic, greenhouse and field conditions. Both of the rhizobacterial strains exhibited a positive effect on growth in terms of shoot height, root length, fresh and dry weight, nodulation and yield over the non-treated control. Co-inoculation of seeds with these strains and Rhizobium RH 2 also reduced the number of wilted plants, when grown in soil infested with Fusarium udum. Gnotobiotic studies confirmed that the suppression of wilt disease was due to the presence of the respective PGPR strains. Seed bacterization with drug-marked mutants of RRLJ 04 and BS 03 confirmed their ability to colonize and multiply along the roots. The results suggest that co-inoculation of these strains with Rhizobium strain RH 2 can be further exploited for enhanced growth, nodulation and yield in addition to control of fusarial wilt in pigeon pea. PMID:25224506

  14. 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

  15. INTERACCIÓN RHIZOBIUM LEGUMINOSARUM BV TRIFOLII Y HONGOS MICORRÍCICOS EN UN ANDISOL CON DIFERENTES NIVELES DE SATURACIÓN DE ALUMINIO / INTERACTION OF RHIZOBIUM LEGUMINOSARUM BV TRIFOLII AND MYCORRHIZAL FUNGI IN AN ANDISOL AT DIFFERENT LEVELS OF ALUMINIUM SATURATION

    Scientific Electronic Library Online (English)

    Claudia G, Castillo R; Rosa, Rubio H; Horacio, Urzúa S; Fernando, Borie B.

    Full Text Available La fitotoxicidad por Al es una seria limitante de la productividad de praderas crecidas sobre suelos volcánicos afectando la nodulación y efectividad de los Rhizobium. El objetivo del estudio consistió en seleccionar cepas de Rhizobium de colección para estudiar su efectividad en Trifolium repens cr [...] ecido en un Andisol con cepas nativas y distinta saturación de Al. Para ello se evaluó previamente en caldo nutritivo la tolerancia a la acidez y toxicidad por Al de 12 cepas de colección mediante control de curvas de crecimiento. Paralelamente, se inocularon los Rhizobium en un Andisol para evaluar su efectividad mediante rendimiento de Trifolium pratense. Se seleccionaron las cepas R-109, R-113 y R-115 para inocularlas en el Andisol utilizando cuatro tratamientos: suelo adicionado de 2 Mg CaCO3 ha-1 (SAl1), un testigo (SAl2) y suelo adicionado de dos niveles de saturación Al (SAl1, SAl4) utilizando Trifolium repens como hospedero. Las plantas mostraron capacidad para asociarse con las especies inoculadas presentando mayor efectividad R-113-SAl1 sinergismo positivo expresado en variables microbiológicas como nodulación (16 nódulos maceta-1), esporas de hongos micorrícicos arbusculares, HMA (384 esporas 100g-1), colonización HMA (45%) junto con variables agronómicas alcanzándose un incremento de biomasa foliar (93,5%) frente al testigo. Niveles más elevados de Al afectaron la inoculación con cepas de colección; así, con R-109 se obtuvo el menor crecimiento radical y nodulación respecto al suelo natural mientras que R-113 fue la cepa más efectiva. Abstract in english Aluminium phytotoxicity is a serious limitation of the productivity of prairies growing on volcanic soil by affecting nodulation and effectiveness of Rhizobium. The aim of this study was to select Rhizobium strains to determine the effect as inoculant on Trifolium repens cropped in an Andisol with d [...] ifferent aluminium saturation levels. Acidity tolerance (pH 4.5 and 6.0) of twelve Rhizobium strains of collection at three Al levels (100, 200, 300 µM) was evaluated in mineral nutritive medium vitro. Simultaneously, in a greenhouse trial, strains effectivity were tested by inoculation of Trifolium pratense growing in an acidic Andisol and compared with dry matter accumulation produced by native strains. According to the results of this two trials, three Rhizobium strains (R-109, R-113 and R-115) were selected to study the effect of their inoculation on Trifolium repens growth cropped in an Andisol at four Al saturation levels (SAl1 to SAl4). In addition, the effect on arbuscular mycorrhizal propagules was also studied. Plants showed different capacity for association with the inoculated strains giving the best response R-113 at SAl1 level with positive synergism expressed by microbiological parameters such as high nodulation (16 nodules pot-1), AMF spore number (384 spores 100 g-1), root colonization percentage (45%), together with agronomical variables with an increase of aerial phytomass (93,5%) in comparison with the control. Higher Al levels had an deleterious effect on the inoculation of collection strains; therefore, with R-109 strain inoculation the smallest root growth and nodulation were observed in comparison with soil with native strains whereas R-113 was the more effective one.

  16. 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

  17. 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.

  18. 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.)

  19. 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.

  20. 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

  1. Identification of a nodD-dependent locus in the Rhizobium strain NGR234 activated by phenolic factors secreted by soybeans and other legumes.

    Science.gov (United States)

    Bassam, B J; Djordjevic, M A; Redmond, J W; Batley, M; Rolfe, B G

    1988-04-01

    Transfer of the strain NGR234nodD 1 gene into the narrow host range R. trifolii strain ANU843 on either a 6.7-kb HindIII or 17-kb XhoI fragment broadens the host range of this bacterium to include the tropical legumes Vigna unguiculata, Glycine ussuriensis, Leucaena leucocephala, and siratro (Macroptilium atropurpureum). Contrary to previous data (Bassam et al. 1986), mutagenesis of the 17-kb XhoI fragment with a mini-Mu lac transposon (Mu dII1734) showed that a functional nodD 1 gene was essential for extended host range. Gene expression studies using both Mu dII1734 fusions and a promoter-cloning vector indicated that several loci, including the nodD 1 gene, are constitutively expressed. No evidence was found for regulation of the strain NGR234 nodD 1 gene by its product. Another locus nod-81, was induced only in the presence of exudates from various plant species, including soybean (Glycine max). Whereas the expression of nod-81 was dependent on the presence of a functional nodD 1 gene product, a regulatory nod-box DNA sequence was not detected 5' to this gene by using available oligonucleotide hybridization probes. The nod-81 locus was induced by genistein, daidzein, naringenin, and coumestrol from both cotyledon and root tissue of freshly germinated soybean seedlings. A broad spectrum of commercially available phenolic compounds stimulated induction of the nod-81 locus, including some that antagonize nod gene induction in other Rhizobium species. The nodD 1 gene product from strain NGR234 was shown to determine the spectrum of compounds that induce nod-81 expression. PMID:2980201

  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. 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)

  4. 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

  5. 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.

  6. 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 decreased both the proportions of belowground dry matter to total dry matter production and nodule dry matter to total belowground dry matter production. The total dry matter yield and N accumulation was greater in the symbiosis with strain 1044, whereas the accumulation of N in the roots plus nodules 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 in the plant cytosol, or on the pools of the Krebs cycle intermediates or related compounds in the nodules.

  7. 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

  8. 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

  9. 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

  10. 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.

  11. 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

  12. Nitrate effects on the nodulation of legumes inoculated with nitrate-reductase-deficient mutants of Rhizobium.

    Science.gov (United States)

    Gibson, A H; Pagan, J D

    1977-01-01

    The effect of nitrate on the symbiotic properties of nitrate-reductase-deficient mutants of a strain of cowpea rhizobia (32H1), and of a strain of Rhizobium trifolii (TA1), were examined; the host species were Macroptilium atropurpureum (DC.) Urb. and Trifolium subterraneum L. Nitrate retarded initial nodulation by the mutant strains to an extent similar to that found with the parent strains. It is therefore unlikely that nitrite produced from nitrate by the rhizobia, plays a significant role in the inhibition of nodulation by nitrate. Nitrite is an inhibitor of nitrogenase, and its possible production in the nodule tissue by the action of nitrate reductase could be responsible for the observed inhibition of nitrogen fixation when nodulated plants are exposed to nitrate. However, the results of this investigation show that nitrogen fixation by the plants nodulated by parent or mutant strains was depressed by similar amounts in the presence of nitrate. No nitrite was detected in the nodules. Nodule growth, and to a lesser extent, the nitrogenase specific activity of the nodules (?mol C2H4g(-1) nodule fr. wt. h(-1)), were both affected by the added nitrate. PMID:24419573

  13. Isolation and the interaction between a mineral-weathering Rhizobium tropici Q34 and silicate minerals.

    Science.gov (United States)

    Wang, Rong Rong; Wang, Qi; He, Lin Yan; Qiu, Gang; Sheng, Xia Fang

    2015-05-01

    The purposes of this study were to isolate and evaluate the interaction between mineral-weathering bacteria and silicate minerals (feldspar and biotite). A mineral-weathering bacterium was isolated from weathered rocks and identified as Rhizobium tropici Q34 based on 16S rRNA gene sequence analysis. Si and K concentrations were increased by 1.3- to 4.0-fold and 1.1- to 1.7-fold in the live bacterium-inoculated cultures compared with the controls respectively. Significant increases in the productions of tartaric and succinic acids and extracellular polysaccharides by strain Q34 were observed in cultures with minerals. Furthermore, significantly more tartaric acid and polysaccharide productions by strain Q34 were obtained in the presence of feldspar, while better growth and more citric acid production of strain Q34 were observed in the presence of biotite. Mineral dissolution experiments showed that the organic acids and polysaccharides produced by strain Q34 were also capable of promoting the release of Si and K from the minerals. The results showed that the growth and metabolite production of strain Q34 were enhanced in the presence of the minerals and different mineral exerted distinct impacts on the growth and metabolite production. The bio-weathering process is probably a synergistic action of organic acids and extracellular polysaccharides produced by the bacterium. PMID:25716616

  14. 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...

  15. 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...

  16. Sequence and analysis of the rpoN sigma factor gene of rhizobium sp. strain NGR234, a primary coregulator of symbiosis.

    OpenAIRE

    van Slooten, J C; Cervantes, E; Broughton, W. J.; WONG, C. H.; Stanley, J.

    1990-01-01

    We report the nucleotide sequence of the rpoN gene from broad-host-range Rhizobium sp. strain NGR234 and analyze the encoded RPON protein, a sigma factor. Comparative analysis of the deduced amino acid sequence of RPON from NGR234 with sequences from other gram-negative bacteria identified a perfectly conserved RPON box unique to RPON sigma factors. Symbiotic regulatory phenotypes were defined for a site-directed internal deletion within the coding sequence of the rpoN gene of Rhizobium strai...

  17. Host-specific regulation of nodulation genes in Rhizobium is mediated by a plant-signal, interacting with the nodD gene product

    OpenAIRE

    Horvath, Beatrix; Bachem, Christian W B; Schell, Jeff; Kondorosi, Adam

    1987-01-01

    We have identified a nodD gene from the wide host-range Rhizobium strain MPIK3030 (termed nodD1) which is essential for nodulation on Macroptilium atropurpureum (siratro). Experiments with nodA–lacZ gene fusions demonstrate that the MPIK3030 nodD1 regulates expression of the nodABC genes. Additionally, we used nodC–lacZ fusions of Rhizobium meliloti to show that the MPIK3030 nodD1 gene induces expression of these fusions by interacting with plant factors from siratro and from the non-host Med...

  18. 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.

  19. 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.

  20. 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.

  1. Inoculação do feijoeiro com Rhizobium tropici associada à exsudato de Mimosa flocculosa com diferentes doses de nitrogênio / Rhizobium tropici associated with Mimosa flocculosa exudates inoculation effect on bean plants under different nitrogen rates

    Scientific Electronic Library Online (English)

    Eulene Francisco da, Silva; Marlene Estevão, Marchetti; Luiz Carlos Ferreira de, Souza; Fábio Martins, Mercante; Edson Talarico, Rodrigues; Antonio Carlos Tadeu, Vitorino.

    Full Text Available O presente estudo teve como objetivo avaliar os efeitos da inoculação de rizóbio, associada à adição de exsudatos de sementes de Mimosa flocculosa, e/ou de N-mineral nas características agronômicas do feijoeiro, em sucessão à soja e ao milho. O delineamento experimental foi em blocos casualizados, c [...] om quatro repetições, sendo os tratamentos dispostos em parcelas sub-subdivididas. As culturas soja e milho antecessoras à cultura do feijoeiro formaram as parcelas. As subparcelas foram constituídas pelos tratamentos: testemunha sem inoculação, inoculação de Rhyzobium tropici, estirpes CIAT 899 e PRF 81 e a associação deste com os exsudados das sementes de Mimosa flocculosa. As sub-subparcelas constituiram-se de quatro doses de N aplicadas em cobertura: 0, 40, 80 e 120 kg ha-1. A inoculação de rizóbio associada à adição de exsudato de sementes de Mimosa flocculosa contribuiu para o melhor desenvolvimento da parte aérea do feijoeiro. A adubação nitrogenada reduziu, de forma linear, a nodulação do feijoeiro. O milho como cultura antecessora ao feijão contribuiu para o aumento do peso de 100 grãos e a adição de N combinado não contribuiu para o aumento do número de vagens por planta e produtividade de grãos do feijoeiro, independente da dose utilizada. Abstract in english The aim of this work was to evaluate the effect of the Rhizobium inoculation, associated with seed exudates of Mimosa flocculosa, under different rates of nitrogen fertilization was evaluated in bean crops following soybean (Glycine max L. Merril) and corn (Zea mays L.). The experimental design was [...] randomized blocks with four replications, with treatments arranged in sub-divided parcels. The parcels were constituted of two summer crops preceding the common bean crop: soybean and corn. In the sub-parcels three treatments involving inoculation of the common bean seeds were considered: control treatment without inoculation; bean seeds inoculated with Rhizobium tropici, strains CIAT 899 and PRF 81, and the association of Rhizobium with the exudates of the Mimosa flocculosa seeds. The sub-subparcels received of four doses of nitrogen fertilization applied on covering: 0, 40, 80 and 120 kg ha-1 N. The inoculation of Rhizobium associated with the addition of exudates of Mimosa flocculosa seeds resulted in higher shoot dry weight. Besides that, the nitrogen fertilization, on the tested doses, reduced, in a linear way, the nodulation of the bean plant. It was also verified that corn as a preceding crop for bean has contributed to the increase of the weight of 100 grains, while the addition of combined N did not contribute to the improvement on the number of beans per plant, neither of the grain yield of bean plants, independent of the dose that was used.

  2. Biological nitrogen fixation by Rhizobium sp. native gliricidia (Gliricidia sepium [Jacq.] Kunth ex Walp.) under greenhouse conditions / Fijación biológica de nitrógeno por Rhizobium sp. nativo de matarratón (Gliricidia sepium [Jacq.] Kunth ex Walp.) bajo condiciones de invernadero

    Scientific Electronic Library Online (English)

    Juan Guillermo, Cubillos-Hinojosa; Pablo Ernesto, Milian-Mindiola; Jorge Luis, Hernández-Mulford.

    2011-12-01

    Full Text Available Se realizó un experimento bajo condiciones de invernadero con el fin de evaluar la asociación y fijación biológica de nitrógeno (FBN) en seis cepas nativas de Rhizobium sp. aisladas de nódulos de matarratón y una cepa comercial (Rhizobiol©). Las suspensiones de 106 y 108 células/mL para cada una de [...] las cepas estudiadas y aplicadas en dos ensayos separados: el primero con semillas y la segundo con plántulas de 35 días de edad matarratón. En el ensayo de semilla se calcula el porcentaje acumulado de germinación durante 7 días. En ambos ensayos, después de 42 días en las semillas y 52 días en plántulas se determinó la altura y diámetro del tallo, número de hojas, peso seco de la parte aérea, número de nódulos por planta y el porcentaje de nitrógeno. Todos los tratamientos estimularon la germinación, el crecimiento y FBN, siendo mejor en las cepas nativas a una concentración de 108 células/mL, en comparación con la cepa comercial y el control. Estos resultados indican el efecto positivo ejercido por Rhizobium sp., en la promoción del crecimiento y FBN, que podrían ser utilizados para estudios adicionales para determinar la producción de un biofertilizante, permitiendo potenciar la producción de cultivos de matarratón como alimento de ganado bovino como fuente de proteína en el Centro de Biotecnología del Caribe Abstract in english 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 (Rhizobiol©). Suspensions of 106 and 108 cells/mL for each of the strains s [...] tudied 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

  3. 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.

  4. 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...

  5. 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...

  6. 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

  7. 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...

  8. 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-...

  9. 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)

  10. 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...

  11. 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...

  12. 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...

  13. Oxygen as a key developmental regulator of Rhizobium meliloti N2-fixation gene expression within the alfalfa root nodule.

    OpenAIRE

    Soupène, E; Foussard, M; Boistard, P; Truchet, G; Batut, J.

    1995-01-01

    The symbiotic pattern of expression of Rhizobium meliloti N2-fixation genes is tightly coupled with the histological organization of the alfalfa root nodule and thus is under developmental control. N2-fixation gene expression is induced very sharply at a particular zone of the nodule called interzone II-III that precedes the zone where N2 fixation takes place. We show here that this coupling can be disrupted, hereby resulting in ectopic expression of N2-fixation genes in the prefixing zone II...

  14. 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.

  15. Identification of protein secretion systems and novel secreted proteins in Rhizobium leguminosarum bv. viciae

    Directory of Open Access Journals (Sweden)

    Krehenbrink Martin

    2008-01-01

    Full Text Available Abstract Background Proteins secreted by bacteria play an important role in infection of eukaryotic hosts. Rhizobia infect the roots of leguminous plants and establish a mutually beneficial symbiosis. Proteins secreted during the infection process by some rhizobial strains can influence infection and modify the plant defence signalling pathways. The aim of this study was to systematically analyse protein secretion in the recently sequenced strain Rhizobium leguminosarum bv. viciae 3841. Results Similarity searches using defined protein secretion systems from other Gram-negative bacteria as query sequences revealed that R. l. bv. viciae 3841 has ten putative protein secretion systems. These are the general export pathway (GEP, a twin-arginine translocase (TAT secretion system, four separate Type I systems, one putative Type IV system and three Type V autotransporters. Mutations in genes encoding each of these (except the GEP were generated, but only mutations affecting the PrsDE (Type I and TAT systems were observed to affect the growth phenotype and the profile of proteins in the culture supernatant. Bioinformatic analysis and mass fingerprinting of tryptic fragments of culture supernatant proteins identified 14 putative Type I substrates, 12 of which are secreted via the PrsDE, secretion system. The TAT mutant was defective for the symbiosis, forming nodules incapable of nitrogen fixation. Conclusion None of the R. l. bv. viciae 3841 protein secretion systems putatively involved in the secretion of proteins to the extracellular space (Type I, Type IV, Type V is required for establishing the symbiosis with legumes. The PrsDE (Type I system was shown to be the major route of protein secretion in non-symbiotic cells and to secrete proteins of widely varied size and predicted function. This is in contrast to many Type I systems from other bacteria, which typically secrete specific substrates encoded by genes often localised in close proximity to the genes encoding the secretion system itself.

  16. 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.

  17. 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.

  18. 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

  19. 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.

  20. Regulation of nod factor sulphation genes in Rhizobium tropici CIAT899.

    Science.gov (United States)

    Manyani, H; Sousa, C; Soria Díaz, M E; Gil-Serrano, A; Megías, M

    2001-06-01

    Rhizobium tropici CIAT899 is a tropical symbiont able to nodulate various legumes such as Leucaena, Phaseolus, and Macroptilium. Broad host range of this species is related to its Nod factors wide spectrum. R. tropici contains Nod factors sulphation nod genes, nodHPQ genes, which control nodulation efficiency in Leucaena. To study nodHPQ regulation, we carried out different interposon insertions in its upstream region. One of these generated interruptions, nodI mutant produced nonsulphated Nod factors suggesting a possible dependence of these genes on nodI upstream region. Moreover, analysis results of lacZ transcriptional fusions with these genes in symbiotic plasmid showed dependence of these genes on NodD protein. In order to determine nodHPQ organization, we studied the effect of interposon insertion upstream of each lacZ transcriptional fusion, and the data obtained was used to indicate that nodHPQ belong to the nodABCSUIJ operon. However, comparison between nodP::lacZ beta-galactosidase activity in the symbiotic plasmid and in the pHM500 plasmid (containing nodHPQ genes) suggested constitutive expression in free living, and flavonoid inducible expression in symbiotic conditions. Constitutive nodHPQ expression may play a role in bacterial house-keeping metabolism. On the other hand, the transference of R. tropici nodHPQ genes to other rhizobia that do not present sulphated substitutions demonstrated that NodH protein sulphotransference is specific to C6 at the reducing end. PMID:11467733

  1. Foliar Chlorosis in Symbiotic Host and Nonhost Plants Induced by Rhizobium tropici Type B Strains.

    Science.gov (United States)

    O'connell, K P; Handelsman, J

    1993-07-01

    Rhizobium tropici CIAT899 induced chlorosis in the leaves of its symbiotic hosts, common bean (Phaseolus vulgaris L.), siratro (Macroptilium atropurpureum Urb.), and Leucaena leucocephala (Lam.) de Wit. Chlorosis induction by strains CIAT899 and CT9005, an exopolysaccharide-deficient mutant of CIAT899, required carbon substrate. When the bacteria were added at planting in a solution of mannitol (50 g/liter), as few as 10 cells of CIAT899 were sufficient to induce chlorosis in bean plants. All carbon sources tested, including organic acids and mono- and disaccharides, supported chlorosis induction. The addition of a carbon source did not affect the growth rate or the population density of CT9005 in the bean plant rhizosphere. Cell-free filtrates of cultures of CT9005 did not induce detectable chlorosis. All type B strains of R. tropici tested also induced chlorosis in common bean. Type A strains of R. tropici and all other species of bacteria tested did not induce chlorosis. Several lines of evidence indicated that nodulation was not required for chlorosis induction. Strain RSP900, a pSym-cured derivative of CIAT899, induced chlorosis in wild-type P. vulgaris. In addition, NOD125, a nodulation-defective line of common bean, developed chlorosis when inoculated with CIAT899, but did not develop nodules. CIAT899 consistently induced severe chlorosis in the leaves of the nonhost legumes alfalfa (Medicago sativa L.) and Berseem clover (Trifolium alexandrinum L.), and induced chlorosis in 29 to 58% of the plants tested of sunflower, cucumber, and tomato seedlings, but it did not induce chlorosis in the leaves of corn or wheat. Chlorosis induction in nonhost plants also required carbon substrate. The data are consistent with the hypothesis that R. tropici type B strains produce a chlorosis-inducing factor that affects a wide range of plant species. PMID:16348994

  2. 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...

  3. 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.

  4. 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

  5. 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.

  6. 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.

  7. Genome Sequences of the Lignin-Degrading Pseudomonas sp. Strain YS-1p and Rhizobium sp. Strain YS-1r Isolated from Decaying Wood

    OpenAIRE

    Prabhakaran, Madhu; Couger, Matthew B.; Jackson, Colin A.; Weirick, Tyler; Fathepure, Babu Z.

    2015-01-01

    Pseudomonas sp. strain YS-1p and Rhizobium sp. strain YS-1r were isolated from a lignin-degrading enrichment culture. The isolates degraded lignin-derived monomers, dimers, alkali lignin, and, to a smaller extent (3% to 5%), lignin in switch grass and alfalfa. Genome analysis revealed the presence of a variety of lignin-degrading genes.

  8. Genome Sequences of the Lignin-Degrading Pseudomonas sp. Strain YS-1p and Rhizobium sp. Strain YS-1r Isolated from Decaying Wood

    Science.gov (United States)

    Prabhakaran, Madhu; Couger, Matthew B.; Jackson, Colin A.; Weirick, Tyler

    2015-01-01

    Pseudomonas sp. strain YS-1p and Rhizobium sp. strain YS-1r were isolated from a lignin-degrading enrichment culture. The isolates degraded lignin-derived monomers, dimers, alkali lignin, and, to a smaller extent (3% to 5%), lignin in switch grass and alfalfa. Genome analysis revealed the presence of a variety of lignin-degrading genes. PMID:25744986

  9. 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

  10. 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.

  11. Productivity and nodulation of promising lineages of the Carioca bean group inoculated with Rhizobium tropici or supplemented with nitrogen fertilizer

    Directory of Open Access Journals (Sweden)

    Auro Akio Otsubo

    2013-12-01

    Full Text Available The aim of this study was to evaluate the nodulation and productivity of lineages of the bean group Carioca inoculated with Rhizobium tropici or fertilized with nitrogen. The experiments were conducted in Dourados, MS, Brazil, in 2008 (experiment 1 and 2009 (experiment 2. The experiment was performed in randomized blocks in triplicate in a 2 x 14 factorial, in which the factors were two different forms of nitrogen supply (mineral N or Rhizobia inoculation. We used 14 different bean lineages. The seeds were inoculated with a mixture of the R. tropici strains CIAT 899 (SEMIA 4077 and PRF 81 (SEMIA 4080. For the majority of the new strains tested, the grain productivity of the common bean were similar for plants inoculated with R. tropici and those fertilized with 80 kg N ha-1. The different nodulation and phytotechnical parameter behaviors of some strains demonstrated that the source of N (inoculation of Rhizobium or nitrogen fertilization in studies on breeding for the selection of bean cultivars can directly affect their yield potential.

  12. 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)

  13. 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

  14. 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

  15. “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.

  16. 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.

  17. 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.

  18. 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…

  19. 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.

  20. AVALIAÇÃO DA FIXAÇÃO BIOLÓGICA DO NITROGÊNIO EM GENÓTIPOS DE FEIJOEIROS TOLERANTES A SECA / EVALUATION OF BIOLOGICAL FIXATION OF NITROGEN IN RHIZOBIUM UNDER WATER DEFICIT

    Scientific Electronic Library Online (English)

    Willian, Bucker Moraes; Sebastião, Martins Filho; Giovanni de Oliveira, Garcia; Simone de Paiva, Caetano; Wanderson, Bucker Moraes; Fernando, Carrara Cosmi.

    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 experim [...] ento 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. Abstract in english 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 expe [...] riment 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.

  1. 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

    2015-10-01

    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 synthe- tic signaling circuits. PMID:26310519

  2. 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.

  3. 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

  4. 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.

  5. 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.

  6. 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

  7. 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

  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. 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

  10. 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...

  11. Novel Arrangement of Enhancer Sequences for NifA-Dependent Activation of the Hydrogenase Gene Promoter in Rhizobium leguminosarum bv. viciae? †

    OpenAIRE

    Martínez González, Marta; Colombo Rodriguez, María Victoria; Palacios Alberti, Jose Manuel; Imperial Ródenas, Juan; Ruiz Argüeso, Tomas-Andres

    2008-01-01

    The transcriptional activation of the NifA-dependent !54 promoter of the Rhizobium leguminosarum hydrogenase structural genes hupSL (P1) has been studied through gel retardation analysis and detailed mutagenesis. Gel retardation analysis indicated the existence of a physical interaction between NifA and the promoter. Extensive mutagenesis followed by in vivo expression analysis showed that three sequences of 4 bases each ("170 ACAA "167, "161 ACAA "158, and "145 TTGT "142) are required for ma...

  12. 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...

  13. 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...

  14. 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...

  15. 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...

  16. Endogenous lectins from cultured soybean cells: isolation of a protein immunologically cross-reactive with seed soybean agglutinin and analysis of its role in binding of Rhizobium japonicum

    OpenAIRE

    1986-01-01

    Incubation of Rhizobium japonicum with the cultured soybean cell line SB-1, originally derived from the roots of Glycine max, resulted in specific adhesion of the bacteria to the plant cells. This binding interaction appears to be mediated via carbohydrate recognition, since galactose can inhibit the heterotypic adhesion but glucose cannot. Affinity chromatography, on a Sepharose column derivatized with N- caproyl-galactosamine, of the supernatant fraction of a SB-1 cell suspension after enzy...

  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. 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...

  19. Multiple host-specificity loci of the broad host-range Rhizobium sp. NGR234 selected using the widely compatible legume Vigna unguiculata.

    Science.gov (United States)

    Lewin, A; Rosenberg, C; H Meyer, Z A; Wong, C H; Nelson, L; Manen, J F; Stanley, J; Dowling, D N; Denarie, J; Broughton, W J

    1987-11-01

    Specificity in legume-Rhizobium symbiosis depends on plant and rhizobial genes. As our objective was to study broad host-range determinants of rhizobia, we sought a legume and a Rhizobium with the lowest possible specificity. By inoculating 12 different legumes with a heterogenous collection of 35 fast-growing rhizobia, we found Rhizobium sp. NGR234 to be the Rhizobium and Vigna unguiculata to be the plant with the lowest specificities. Transfer of cloned fragments of the Sym-plasmid pNGR234a into heterologous rhizobia, screening for extension of host-range of the transconjugants to include V. unguiculata, and restriction mapping of the Hsn- and overlapping clones, proved that there were at least three distinct Hsn-regions (HsnI, II, and III) on pNGR234a. HsnI is located next to nodD, HsnII is linked to nifKDH and HsnIII to nodC. In addition to nodulation of Vigna, HsnI conferred upon the transconjugants the ability to nodulate Glycine max, Macroptilium atropurpureum and Psophocarpus tetragonolobus. All three Hsn-regions, when transferred to the appropriate recipients, induced root-hair-curling on M. atropurpureum. Hsn-region III was able to complement a mutation in the host-range gene nodH of R. meliloti strain 2011. Homology to "nod-box"-sequences could be shown only for the sub-clones containing HsnII and HsnIII, thus suggesting different regulation mechanisms for HsnI and HsnII/III. PMID:24301307

  20. 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...

  1. 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

  2. Sequence and analysis of the rpoN sigma factor gene of rhizobium sp. strain NGR234, a primary coregulator of symbiosis.

    Science.gov (United States)

    van Slooten, J C; Cervantes, E; Broughton, W J; Wong, C H; Stanley, J

    1990-10-01

    We report the nucleotide sequence of the rpoN gene from broad-host-range Rhizobium sp. strain NGR234 and analyze the encoded RPON protein, a sigma factor. Comparative analysis of the deduced amino acid sequence of RPON from NGR234 with sequences from other gram-negative bacteria identified a perfectly conserved RPON box unique to RPON sigma factors. Symbiotic regulatory phenotypes were defined for a site-directed internal deletion within the coding sequence of the rpoN gene of Rhizobium strain NGR234: they included quantitative nodulation kinetics on Vigna unguiculata and microscopic analysis of the Fix- determinate nodules of V. unguiculata and Macroptilium atropurpureum. RPON was a primary coregulator of nodulation and was implicated in establishment or maintenance of the plant-synthesized peribacteroid membrane. Phenotypes of rpoN in Rhizobium strain NGR234 could be grouped as symbiosis related, rather than simply pleiotropically physiological as in free-living bacteria such as Klebsiella pneumoniae and Pseudomonas putida. PMID:2211497

  3. Identification and cloning of nodulation genes and host specificity determinants of the broad host-range Rhizobium leguminosarum biovar phaseoli strain CIAT899.

    Science.gov (United States)

    Vargas, C; Martinez, L J; Megias, M; Quinto, C

    1990-11-01

    Rhizobium leguminosarum biovar phaseoli type II strain CIAT899 nodulates a wide range of hosts: Phaseolus vulgaris (beans), Leucaena esculenta (leucaena) and Macroptilium atropurpureum (siratro). A nodulation region from the symbiotic plasmid has been isolated and characterized. This region, which is contained in the overlapping cosmid clones pCV38 and pCV117, is able to induce nodules in beans, leucaena and siratro roots when introduced in strains cured for the symbiotic plasmid, pSym. In addition, this cloned region extends the host range of Rhizobium meliloti and R. leguminosarum biovar (bv.) trifolii wild-type strains to nodulate beans. Analysis of constructed subclones indicates that a 6.4kb HindIII fragment contains the essential genes required for nodule induction on all three hosts. Rhizobium leguminosarum bv. phaseoli type I strain CE3 nodulates only beans. However, CE3 transconjugants harbouring plasmid pCV3802 (which hybridized to a nodD heterologous probe), were capable of eliciting nodules on leucaena and siratro roots. Our results suggest that the CIAT899 DNA region hybridizing with the R. meliloti nodD detector is involved in the extension of host specificity to promote nodule formation in P. vulgaris, L. esculenta and M. atropurpureum. PMID:2082147

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. Synergistic interaction of Rhizobium leguminosarum bv. viciae and arbuscular mycorrhizal fungi as a plant growth promoting biofertilizers for faba bean (Vicia faba L.) in alkaline soil.

    Science.gov (United States)

    Abd-Alla, Mohamed Hemida; El-Enany, Abdel-Wahab Elsadek; Nafady, Nivien Allam; Khalaf, David Mamdouh; Morsy, Fatthy Mohamed

    2014-01-20

    Egyptian soils are generally characterized by slightly alkaline to alkaline pH values (7.5-8.7) which are mainly due to its dry environment. In arid and semi-arid regions, salts are less concentrated and sodium dominates in carbonate and bicarbonate forms, which enhance the formation of alkaline soils. Alkaline soils have fertility problems due to poor physical properties which adversely affect the growth and the yield of crops. Therefore, this study was devoted to investigating the synergistic interaction of Rhizobium and arbuscular mycorrhizal fungi for improving growth of faba bean grown in alkaline soil. A total of 20 rhizobial isolates and 4 species of arbuscular mycorrhizal fungi (AMF) were isolated. The rhizobial isolates were investigated for their ability to grow under alkaline stress. Out of 20 isolates 3 isolates were selected as tolerant isolates. These 3 rhizobial isolates were identified on the bases of the sequences of the gene encoding 16S rRNA and designated as Rhizobium sp. Egypt 16 (HM622137), Rhizobium sp. Egypt 27 (HM622138) and Rhizobium leguminosarum bv. viciae STDF-Egypt 19 (HM587713). The best alkaline tolerant was R. leguminosarum bv. viciae STDF-Egypt 19 (HM587713). The effect of R. leguminosarum bv. viciae STDF-Egypt 19 and mixture of AMF (Acaulospora laevis, Glomus geosporum, Glomus mosseae and Scutellospora armeniaca) both individually and in combination on nodulation, nitrogen fixation and growth of Vicia faba under alkalinity stress were assessed. A significant increase over control in number and mass of nodules, nitrogenase activity, leghaemoglobin content of nodule, mycorrhizal colonization, dry mass of root and shoot was recorded in dual inoculated plants than plants with individual inoculation. The enhancement of nitrogen fixation of faba bean could be attributed to AMF facilitating the mobilization of certain elements such as P, Fe, K and other minerals that involve in synthesis of nitrogenase and leghaemoglobin. Thus it is clear that the dual inoculation with Rhizobium and AMF biofertilizer is more effective for promoting growth of faba bean grown in alkaline soils than the individual treatment, reflecting the existence of synergistic relationships among the inoculants. PMID:23920230

  9. 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.

  10. 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.

  11. Bouvard et Pécuchet et le savoir médical

    Directory of Open Access Journals (Sweden)

    Norioki Sugaya

    2009-01-01

    Full Text Available Le présent article a pour objet le dossier médical que Flaubert a constitué pour la préparation du chapitre III de Bouvard et Pécuchet. Ce dossier considérable, qui contient des notes de lecture prises par le romancier en vue de la rédaction du chapitre médical, nous permet de comprendre à quel point le « comique d’idées » propre au roman encyclopédique est le produit d’un travail intense sur le savoir. L’écriture romanesque de Bouvard explore en effet les configurations épistémologiques de chaque discipline, et met au jour surtout ses apories et ses insuffisances. Nous nous proposons donc d’aborder le dossier médical pour saisir le sens de l’excès documentaire pour l’esthétique flaubertienne. Notre étude se compose de trois parties. D’abord, nous étudierons la composition du dossier en nous demandant quels ouvrages médicaux a lu l’auteur de Bouvard. Ensuite, nous essaierons d’examiner le travail critique de Flaubert pratiqué sur les discours du savoir, en particulier la manière dont il traque et construit des contradictions. Enfin, nous analyserons un épisode du roman, celui de la fièvre typhoïde de Gouy, dont l’étude de la genèse nous montrera l’inscription de l’épistémologique dans la représentation romanesque.This article proposes to study the medical documents gathered by Flaubert for the preparation of Chapter III of Bouvart et Pécuchet. This substantial file, which contains reading notes taken by the novelist for the writing of the medical chapter, allows us to understand to what extent the “comic of ideas”, characteristic of the encyclopedic novel, is the result of an intensive work on knowledge. Indeed, the novelistic writing of Bouvard explores the epistemological configurations of each discipline, and in particular reveals its aporia and its insufficiencies. We have chosen to focus on the medical file in order to understand the meaning of the documentary excess with respect toFlaubert’s esthetics. First we shall study the components of the file, identifying the medical works read by the author of Bouvard. Then we will examine Flaubert’s critical reflection on knowledge, in particular the way he hunts down and constructs contradictions. Finally, we will analyze an episode in the novel, that of Gouy’s typhoid fever. We shall study its genesis which will show the presence of the epistemological in the art of the novel.

  12. 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

  13. Biofiltration of residual fertilizer nitrate and atrazine by Rhizobium meliloti in saturated and unsaturated sterile soil columns.

    Science.gov (United States)

    Mehmannavaz, R; Prasher, S O; Markarian, N; Ahmad, D

    2001-04-15

    This study was undertaken to investigate whether microbial bioaugmentation of subsurface soil with subsurface irrigation could be used as a biofiltration/biocontrol technology for agricultural pollutants. Nine Plexiglas columns, 458 mm long x 139 mm in diameter, were packed with a sterilized sandy loam soil. Subsurface irrigation, through a controlled water table management system, was used to deliver bacteria, Rhizobium meliloti A-025, to the soil and to maintain aerobic (unsaturated) or anaerobic (saturated) conditions in the columns. Nitrate and atrazine, a fertilizer and a corn herbicide, were applied to the soil surface, and leaching was affected by simulated rainfall events. The soil and drainage waters were analyzed for nitrate and atrazine residues after each rainfall simulation throughout the experimental period during which the soil was kept saturated for a total of 80 days and unsaturated for a total of 70 days. The monitoring of transport and survival of the implanted bacterial strain (A-025) showed that subsurface irrigation was successful in introducing and transporting the bacteria throughout the soil columns. During the saturated period, significantly more (95% probability) nitrate-N leached into the drainage waters from the control columns than from the bioaugmented columns; the increase being 450% or more for the abiotic control columns. The amount of atrazine that leached into the drainage waters during the unsaturated period was also significantly more from control columns as opposed to bioaugmented columns, with the increase being 262%. PMID:11329710

  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. Enhanced growth and nodulation of pigeon pea by co-inoculation of Bacillus strains with Rhizobium spp.

    Science.gov (United States)

    Rajendran, Geetha; Sing, Falguni; Desai, Anjana J; Archana, G

    2008-07-01

    Endophytic bacteria which are known to reside in plant tissues have often been shown to promote plant growth. Present study deals with the isolation of putative endophytes from the surface sterilized root nodules of pigeon pea (Cajanus cajan) designated as non-rhizobial (NR) isolates. Three of these non-rhizobial isolates called NR2, NR4 and NR6 showed plant growth promotion with respect to increase in plant fresh weight, chlorophyll content, nodule number and nodule fresh weight when co-inoculated with the rhizobial bioinoculant strain IC3123. The three isolates were neither able to nodulate C. cajan nor did they show significant plant growth promotion when inoculated alone without Rhizobium spp. IC3123. All the three isolates were gram positive rods with NR2 and NR4 showing endospore formation and formed one single cluster in Amplified Ribosomal DNA Restriction Analysis (ARDRA). Partial sequences of 16S rRNA genes of NR4 and NR6 showed 97% similarity to Bacillus megaterium. The Bacillus strains NR4 and NR6 were able to produce siderophores which the rhizobial bioinoculant IC3123 was able to cross-utilize. Under iron starved conditions IC3123 showed enhanced growth in the presence of the Bacillus isolates indicating that siderophore mediated interactions may be underlying mechanism of beneficial effect of the NR isolates on nodulation by IC3123. PMID:17826983

  16. 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

  17. 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

  18. 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

  19. NodZ of Bradyrhizobium extends the nodulation host range of Rhizobium by adding a fucosyl residue to nodulation signals.

    Science.gov (United States)

    López-Lara, I M; Blok-Tip, L; Quinto, C; Garcia, M L; Stacey, G; Bloemberg, G V; Lamers, G E; Lugtenberg, B J; Thomas-Oates, J E; Spaink, H P

    1996-07-01

    The nodulation genes of rhizobia are involved in the production of the lipo-chitin oligosaccharides (LCO), which are signal molecules required for nodule formation. A mutation in nodZ of Bradyrhizobium japonicum results in the synthesis of nodulation signals lacking the wild-type 2-O-methylfucose residue at the reducting-terminal N-acetylglucosamine. This phenotype is correlated with a defective nodulation of siratro (Macroptilium atropurpureum). Here we show that transfer of nodZ to Rhizobium leguminosarum blovar (bv) viciae, which produces LCOs that are not modified at the reducing-terminal N-acetylglucosamine, results in production of LCOs with a fucosyl residue on C-6 of the reducing-terminal N-acetylglucosamine. This finding, together with in vitro enzymatic assays, indicates that the product of nodZ functions as a fucosyltransferase. The transconjugant R. leguminosarum strain producing fucosylated LCOs acquires the capacity to nodulate M. atropurpureum, Glycine soja, Vigna unguiculate and Leucaena leucocephala. Therefore, nodZ extends the narrow host range of R. leguminosarum bv. viciae to include various tropical legumes. However, microscopic analysis of nodules induced on siratro shows that these nodules do not contain bacteroids, showing that transfer of nodZ does not allow R. leguminosarum to engage in a nitrogen-fixing symbiosis with this plant. PMID:8858593

  20. A Comparative Study of the Physiology of Symbioses Formed by Rhizobium japonicum with Glycine max, Vigna unguiculata, and Macroptilium atropurpurem.

    Science.gov (United States)

    Keyser, H H; van Berkum, P; Weber, D F

    1982-12-01

    Although Rhizobium japonicum nodulates Vigna unguiculata and Macroptilium atropurpurem, little is known about the physiology of these symbioses. In this study, strains of R. japonicum of varying effectiveness on soybean were examined. The nonhomologous hosts were nodulated by all the strains tested, but effectiveness was not related to that of the homologous host. On siratro, compared to soybean, many strains reversed their relative effectiveness ranking. Both siratro and cowpea produced more dry matter with standard cowpea rhizobia CB756 and 176A22 than with the strains of R. japonicum. Strains USDA33 and USDA74 were more effective with siratro and cowpea than with soybean. The strain USDA122 expressed high rates of hydrogenase activity in symbiosis with the cowpea as well as the soybean host. The strains USDA61 and USDA74 expressed low levels of hydrogenase activity in symbiosis with cowpea, but no activity was found with soybean. Our results indicate host influence for the expression of hydrogenase activity, and suggest the possibility of host influence of nitrogenase for the allocation of electrons to N(2) and H(+). PMID:16662732

  1. 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.

  2. 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

  3. 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)

    Bromfield, E S P; Tambong, J T; Cloutier, S; Prévost, D; Laguerre, G; van Berkum, P; Thi, T V Tran; Assabgui, R; Barran, L R

    2010-02-01

    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 diverse genotypes of Ensifer, Rhizobium and Phyllobacterium species based on sequence analysis of ribosomal (16S and 23S rRNA) and protein-encoding (atpD and recA) genes, Southern hybridization/RFLP and a range of phenotypic characteristics. Among phage-resistant bacteria, one genotype of Rhizobium sp. predominated on alfalfa (frequency approximately 68 %) but was recovered infrequently ( approximately 1 %) from sweet clover. A second genotype was isolated infrequently only from alfalfa. These genotypes fixed nitrogen poorly in association with sweet clover and Phaseolus vulgaris, but were moderately effective with alfalfa. They produced a near-neutral reaction on mineral salts agar containing mannitol, which is atypical of the genus Rhizobium. A single isolate of Ensifer sp. and two of Phyllobacterium sp. were recovered only from sweet clover. All were highly resistant to multiple antibiotics. Phylogenetic analysis indicated that Ensifer sp. strain T173 is closely related to, but separate from, the non-symbiotic species 'Sinorhizobium morelense'. Strain T173 is unique in that it possesses a 175 kb symbiotic plasmid and elicits ineffective nodules on alfalfa, sweet clover, Medicago lupulina and Macroptilium atropurpureum. The two Phyllobacterium spp. were non-symbiotic and probably represent bacterial opportunists. Three genotypes of E. meliloti that were symbiotically effective with alfalfa and sweet clover were encountered infrequently. Among phage-susceptible isolates, two genotypes of E. medicae were encountered infrequently and were highly effective with alfalfa, sweet clover and Medicago polymorpha. The ecological and practical implications of the findings are discussed. PMID:19875436

  4. Rhizobium meliloti 1021 has three differentially regulated loci involved in glutamine biosynthesis, none of which is essential for symbiotic nitrogen fixation.

    OpenAIRE

    De Bruijn, F J; Rossbach, S.; Schneider, M.; Ratet, P; Messmer, S; Szeto, W W; Ausubel, F. M.; Schell, J

    1989-01-01

    We have cloned and characterized three distinct Rhizobium meliloti loci involved in glutamine biosynthesis (glnA, glnII, and glnT). The glnA locus shares DNA homology with the glnA gene of Klebsiella pneumoniae, encodes a 55,000-dalton monomer subunit of the heat-stable glutamine synthetase (GS) protein (GSI), and complemented an Escherichia coli glnA mutation. The glnII locus shares DNA homology with the glnII gene of Bradyrhizobium japonicum and encodes a 36,000-dalton monomer subunit of th...

  5. Conservation of PcaQ, a transcriptional activator of pca genes for catabolism of phenolic compounds, in Agrobacterium tumefaciens and Rhizobium species.

    OpenAIRE

    Parke, D.

    1996-01-01

    In Agrobacterium tumefaciens A348, control of five genes for catabolism of the phenolic compound protocatechuate to beta-ketoadipate is exerted by the gene pcaQ. The product of pcaQ is a transcriptional activator which is distinct from regulators of the beta-ketoadipate pathway characterized in other bacterial groups. An investigation of whether pcaQ is present and conserved in related Rhizobium species employed Southern hybridization and an agrobacterial pcaD::LacZ promoter probe plasmid. Th...

  6. Restriction mapping of DNA of temperate Rhizobium meliloti phage 16-3: comparison of genetic and physical maps indicates a long, genetically silent chromosomal arm.

    Science.gov (United States)

    Dallmann, G; Orosz, L; Sain, B

    1979-11-01

    The complete restriction map of DNA (61.57 Kb) of temperate Rhizobium meliloti phage 16-3 has been constructed for enzymes BglII, HindIII, HpaI, KpnI, and a partial map for EcoRI. The strategy employed for mapping included the analysis of double, triple and partial digests; comparison of wild type and deletion mutants; and detailed analysis of subfragments, exploiting the presence of cohesive ends of the phage. Comparison of the genetic and physical maps indicates that one arm of the chromosome is genetically silent and/or contains nonessential genes. PMID:293461

  7. 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.

  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. Rhizobium tibeticum activated with a mixture of flavonoids alleviates nickel toxicity in symbiosis with fenugreek (Trigonella foenum graecum L.).

    Science.gov (United States)

    Abd-Alla, Mohamed Hemida; Bashandy, Shymaa Ryhan; Bagy, Magdy Khalil; El-enany, Abdel-Wahab Elsadk

    2014-07-01

    The objective of this study is to explore the response of an activated Rhizobium tibeticum inoculum with a mixture of hesperetin (H) and apigenin (A) to improve the growth, nodulation, and nitrogen fixation of fenugreek (Trigonella foenum graecum L.) grown under nickel (Ni) stress. Three different sets of fenugreek seed treatments were conducted, in order to investigate the activated R. tibeticum pre-incubation effects on nodulation, nitrogen fixation and growth of fenugreek under Ni stress. Group (I): uninoculated seeds with R. tibeticum, group (II): inoculated seeds with uninduced R. tibeticum group (III): inoculated seeds with induced R. tibeticum. The present study revealed that Ni induced deleterious effects on rhizobial growth, nod gene expression, nodulation, phenylalanine ammonia-lyase (PAL) and glutamine synthetase activities, total flavonoids content and nitrogen fixation, while the inoculation with an activated R. tibeticum significantly improved these values compared with plants inoculated with uninduced R. tibeticum. PAL activity of roots plants inoculated with induced R. tibeticum and grown hydroponically at 75 and 100 mg L(-1) Ni and was significantly increased compared with plants receiving uninduced R. tibeticum. The total number and fresh mass of nodules, nitrogenase activity of plants inoculated with induced cells grown in soil treated up to 200 mg kg(-1) Ni were significantly increased compared with plants inoculated with uninduced cells. Plants inoculated with induced R. tibeticum dispalyed a significant increase in the dry mass compared with those treated with uninduced R. tibeticum. Activation of R. tibeticum inoculum with a mixture of hesperetin and apigenin has been proven to be practically important in enhancing nodule formation, nitrogen fixation and growth of fenugreek grown in Ni contaminated soils. PMID:24740320

  10. 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

  11. Structural elucidation of the outer core tetrasaccharide isolated from the LPS of Rhizobium leguminosarum bv. trifolii strain 24.

    Science.gov (United States)

    Turska-Szewczuk, Anna; Russa, Ryszard; Kara?, Magdalena A; Danikiewicz, Witold; Spólnik, Grzegorz

    2015-05-29

    The outer core oligosaccharide (OS) was isolated from the lipopolysaccharide (LPS) of Rhizobium leguminosarum bv. trifolii strain 24 after Smith degradation and then studied by sugar and methylation analyses along with NMR and mass spectrometry methods. Negative-ion electrospray (ESI-MS) mass spectrum showed two molecular ions at m/z 686.3 and 728.3, which corresponded to the core OS having the composition Rha2QuiNAcKdh. The mass difference between both ions indicated that the higher molecule mass represented the mono O-acetylated variant of the OS. The sequence of the oligosaccharide was reflected in CID MS/MS spectra. In turn, NMR spectroscopy confirmed the composition and glycosylation pattern of the core OS and provided additional evidence on its structure. 2D NMR experiments revealed that the terminal Rhap is acetylated at position O-2. Moreover, 3-deoxyheptulosonic acid (Kdh), which was detected at the reducing terminus of the OS, was evidently derived from the Kdo as a result of Smith degradation. In addition, the higher intensity of signals for a six-membered pyranose ring of Kdhp over 2,7-anh-Kdhf seemed to indicate prevalence of this form of the sugar in the OS-derived species. Based on the data obtained, the following structure of the outer core tetrasaccharide, which probably links the O-chain polysaccharide to the inner core in the LPS of R. leguminosarum bv. trifolii strain 24, was established: ?-L-Rhap-2-OAc*-(1-->3)-?-L-Rhap-(1-->3)-?-D-QuipNAc-(1-->4)-Kdo * ~ 50%. . PMID:25880336

  12. PERANAN FUNGI MIKORIZA ARBUSKULA, MIKROORGANISME PELARUT FOSFAT, RHIZOBIUM SP DAN ASAM HUMIK UNTUK MENINGKATKAN PERTUMBUHAN DAN PRODUKTIVITAS LEGUM Calopogonium mucunoides PADA TANAH LATOSOL DAN TAILING TAMBANG EMAS DI PT. ANEKA TAMBANG

    Directory of Open Access Journals (Sweden)

    - Karti

    2014-06-01

    Full Text Available Latosols soil conditions are poor in nutrients and tailing of gold mine contain heavy metal causes low productivity of forage. The objective of this research to study the best combination of soil potential microorganisms and soil conditioner that can promote the growth and production of legume crops Calopogonium mucunoides Desv. Seven treatments used were A: control, B: arbuscular mycorrhizal fungi (AMF, C: AMF + Rhizobium, D: AMF + Phosphate Solubilizing Bacteria (BPF, E: AMF + Humic Acid, F: AMF + BPF + Rhizobium, G: AMF + BPF + Humic Acid + Rhizobium. Variables measured were the root dry weight, shoot dry weight, spread length, number of trifoliate leaves, the number of active root nodules, the percentage of root infection. Augmentation of soil microorganisms and soil conditioner not effective enough to improve plant growth of Calopogonium mucunoides Desv because plants can still adapt and grow well on latosols. Plants grown on tailings provide the best response is G (AMF+ Humic Acid + Rhizobium, although the rate of growth is not as good as plants grown in latosols.

  13. VsENOD5, VsENOD12 and VsENOD40 expression during Rhizobium-induced nodule formation on Vicia sativa roots.

    DEFF Research Database (Denmark)

    Vijn, I; Yang, W C

    1995-01-01

    We isolated ENOD5, ENOD12 and ENOD40 homologues from Vicia sativa and studied their expression pattern during Rhizobium-induced nodule formation. Comparison of the VsENOD40 nucleotide sequence with the pea, soybean and alfalfa ENOD40 sequences showed that the sequences contain two conserved regions, called region I and region II. Comparison of all the potential open reading frames (ORFs) showed that all the five different ENOD40 clones encode a highly conserved small polypeptide of 12 or 13 amino acids encoded by an ORF located in region I. Furthermore we studied with in situ hybridization the expression pattern of VsENOD5, VsENOD12 and VsENOD40 during Rhizobium-induced nodule formation. Although the expression of these genes is largely similar to that of the pea counterparts, differences where found for the expression of VsENOD12 and VsENOD40 in Vicia. VsENOD12 is expressed in the whole prefixation zone II, whereas in pea ENOD12 is only expressed in the distal part of this zone. VsENOD40 is expressed in the uninfected cells of interzone II-III, while in pea ENOD40 is expressed in both the uninfected and infected cells of this zone. Udgivelsesdato: 1995-Sep

  14. Effect of aldicarb on growth and radio-carbon (14C) and radio-phosphorus (32P) assimilation by Rhizobium japonicum

    International Nuclear Information System (INIS)

    In vitro studies on the effect of aldicarb (2-methyl-2-(methyl thio) propionaldehde-o-methyl carbamoyl oxime), a soil applied systemic insecticide, on Rhizobium japonicum revealed that the chemical (at 1,2 and 5 ppm levels) stimulated the growth of the organism initially upto 48 hr which declined thereafter upto 72 hr. The incorporation of 14C-glucose by the cells considerably reduced due to the insecticide treatment. The production of extracellular, water-soluble slime (polysacchardes) was also reduced considerably with increased concentrations of the chemical. However, the incorporation of 14C-radio-activity in the extracellular slime generally enhanced due to the treatment, upto 6 hr after injection of the radioactivity, which declined significantly later at 15 hr, indicating a qualitative difference in the extracellular polysaccharides produced by the insecticide treated cells. The insecticide treatment drastically reduced the incorporation of 32P-disodium hydrogen phosphate into Rhizobium cells, but enhanced the specific activity of the extracellular polysacchrides. (author)

  15. Cicer canariense, an endemic legume to the Canary Islands, is nodulated in mainland Spain by fast-growing strains from symbiovar trifolii phylogenetically related to Rhizobium leguminosarum.

    Science.gov (United States)

    Martínez-Hidalgo, Pilar; Flores-Félix, José-David; Menéndez, Esther; Rivas, Raúl; Carro, Lorena; Mateos, Pedro F; Martínez-Molina, Eustoquio; León-Barrios, Milagros; Velázquez, Encarna

    2015-07-01

    Cicer canariense is a threatened endemic legume from the Canary Islands where it can be nodulated by mesorhizobial strains from the symbiovar ciceri, which is the common worldwide endosymbiont of Cicer arietinum linked to the genus Mesorhizobium. However, when C. canariense was cultivated in a soil from mainland Spain, where the symbiovar ciceri is present, only fast-growing rhizobial strains were unexpectedly isolated from its nodules. These strains were classified into the genus Rhizobium by analysis of the recA and atpD genes, and they were phylogenetically related to Rhizobium leguminosarum. The analysis of the nodC gene showed that the isolated strains belonged to the symbiovar trifolii that harbored a nodC allele (? allele) different to that harbored by other strains from this symbiovar. Nodulation experiments carried out with the lacZ-labeled strain RCCHU01, representative of the ? nodC allele, showed that it induced curling of root hairs, infected them through infection threads, and formed typical indeterminate nodules where nitrogen fixation took place. This represents a case of exceptional performance between the symbiovar trifolii and a legume from the tribe Cicereae that opens up new possibilities and provides new insights into the study of rhizobia-legume symbiosis. PMID:26032249

  16. Broad-host-range Rhizobium species strain NGR234 secretes a family of carbamoylated, and fucosylated, nodulation signals that are O-acetylated or sulphated.

    Science.gov (United States)

    Price, N P; Reli?, B; Talmont, F; Lewin, A; Promé, D; Pueppke, S G; Maillet, F; Dénarié, J; Promé, J C; Broughton, W J

    1992-12-01

    Rhizobium species strain NGR234 is the most promiscuous known rhizobium. In addition to the non-legume Parasponia andersonii, it nodulates at least 70 genera of legumes. Here we show that the nodulation genes of this bacterium determine the production of a large family of Nod-factors which are N-acylated chitin pentamers carrying a variety of substituents. The terminal non-reducing glucosamine is N-acylated with vaccenic or palmitic acids, is N-methylated, and carries varying numbers of carbamoyl groups. The reducing N-acetyl-glucosamine residue is substituted on position 6 with 2-O-methyl-L-fucose which may be acetylated or sulphated or non-substituted. All three internal residues are N-acetylated. At pico- to nanomolar concentrations, these signal molecules exhibit biological activities on the tropical legumes Macroptilium and Vigna (Phaseoleae), as well as on both the temperate genera Medicago (Trifoliae) and Vicia (Viciae). These data strongly suggest that the uniquely broad host range of NGR234 is mediated by the synthesis of a family of varied sulphated and non-sulphated lipo-oligosaccharide signals. PMID:1474899

  17. Micorriza arbuscular e rizóbios no enraizamento e nutrição de mudas de angico-vermelho / Arbuscular mycorrhizae and rhizobium in rooting and nutrition of angico-vermelho seedlings

    Scientific Electronic Library Online (English)

    Poliana Coqueiro, Dias; Muriel da Silva Folli, Pereira; Maria Catarina, MegumiKasuya; Haroldo Nogueira de, Paiva; Leandro Silva de, Oliveira; Aloisio, Xavier.

    2012-12-01

    Full Text Available O objetivo deste estudo foi avaliar o efeito da inoculação dos fungos micorrízicos arbusculares (FMAs) e rizóbio no enraizamento, crescimento e nutrição de mudas de angico-vermelho (Anadenanthera macrocarpa (Benth) Brenan) propagadas via miniestaquia. Foram utilizadas seis progênies, das quais foram [...] confeccionadas miniestacas com um par de folhas inteiras, bem como tubetes de 55 cm³ contendo substrato comercial Bioplant®. Foram testados quatro tratamentos: 8 kg m-3 de superfosfato simples (SS) misturados ao substrato; 4 kg m-3 de SS misturados ao substrato; 4 kg m-3 de SS misturados ao substrato e adição de suspensão contendo rizóbios; e 4 kg m-3 de SS e adição de suspensão contendo rizóbios e 5 g de solo contendo esporos de FMAs. Não houve interação entre os tratamentos para percentagem de sobrevivência das miniestacas e percentagem de miniestacas com raízes observadas na extremidade inferior do tubete, na saída da casa de vegetação (30 dias) e da casa de sombra (40 dias), provavelmente em função do sistema radicular ainda estar em formação. Houve diferenças entre as progênies para percentagem de sobrevivência das miniestacas, percentagem de miniestacas com raízes observadas na extremidade inferior do tubete, altura, diâmetro de colo e massa seca da parte aérea. As avaliações das características de crescimento das miniestacas enraizadas, principalmente com relação à sobrevivência a pleno sol (140 dias), evidenciam a eficiência dos rizóbios e FMAs na produção de mudas desta espécie. Conclui-se que a associação simbiótica com rizóbio e/ou FMA favorece a produção de mudas de A. macrocarpa via miniestaquia. Abstract in english The objective of this study was to evaluate the effect of inoculation of arbuscular mycorrhizae fungi (AMF) and rhizobium on rooting, growth and nutrition of seedlings of angico-red (Anadenanthera macrocarpa (Benth) Brenan) propagated by minicutting. Six progenies were used, of which were prepared c [...] uttings with a pair of complete leaves. It was used a 55 cm³container filled with commercial substrate Bioplant®. Four treatments were tested: 8 kg m-3 of superphosphate (SS) added to substrate; 4 kg m-3 SS added to substrate; 4 kg m-3 SS added to substrate and adition of a suspension solution containing rhizobium; 4 kg m-3 SS and suspension solution containing rhizobium plus 5 g of soil contaminated by AMF spores. There was no interaction among treatments for survival rate of cuttings and roots observed at bottom of the container, evaluated in the greenhouse exit (30 days) and the shade house exit (40 days), probably because the root system was still in formation. There were differences among the progeny for survival rate of the shoots, the percentage of cuttings with roots observed at bottom of the container, height, stem diameter and shoot dry weight. The evaluations of the growth characteristics of the cuttings in, particularly with respect to survival at full sun (140 days), demonstrate the efficiency of rhizobium and AMF on seedling production of this species. We conclude that the symbiotic association with rhizobium and / or FMA favors the production of seedlings of A. macrocarpa by minicutting.

  18. 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...

  19. 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.

  20. 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. 

  1. 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.

  2. 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)

  3. Compatibilidade entre a inoculação de rizóbios e fungicidas aplicados em sementes de feijoeiro-comum / Compatibility between rhizobium inoculation and fungicide application in seeds of common beans

    Scientific Electronic Library Online (English)

    Maurício Rocha, Kintschev; Augusto César Pereira, Goulart; Fábio Martins, Mercante.

    2014-12-01

    Full Text Available O objetivo do presente estudo foi avaliar os efeitos do tratamento de sementes de feijoeiro com diferentes fungicidas na sobrevivência de estirpe de Rhizobium tropici (SEMIA 4077) e Rhizobium freirei (SEMIA 4080), na nodulação das plantas e na produtividade da cultura. Foram conduzidos dois ensaios [...] em substrato esterilizado, sob condições de casa de vegetação e um ensaio no campo experimental da Embrapa Agropecuária Oeste, em Dourados, MS, num Latossolo Vermelho distroférrico típico. Os fungicidas (princípios ativos) utilizados nos ensaios foram: (1) carbendazim + tiram (Produto A); (2) carbendazim + tiram (Produto B); (3) carboxin + tiram; (4) fludioxonil + metalaxil-M; (5) fludioxonil + metalaxil-M + tiabendazol; (6) fluazinam + tiofanato metílico; (7) fipronil + tiofanato metílico + piraclostrobina; (8) clorotalonil + tiofanato metílico. A sobrevivência das estirpes de R. tropici inoculadas nas sementes de feijoeiro foi afetada pela aplicação dos fungicidas, principalmente por aqueles com modo de ação de contato. Observou-se ainda, com a aplicação dos fungicidas, redução na nodulação das plantas de feijoeiro, especialmente da massa nodular, tanto nos ensaios conduzidos em substrato esterilizado, em casa de vegetação, quanto no experimento a campo, onde também observou-se redução na produtividade do feijoeiro pela aplicação da maioria dos fungicidas avaliados. Os fungicidas que mais afetaram o rendimento de grãos foram carbendazim + tiram (Produto B) e carboxin + tiram. Os produtos fipronil + tiofanato metílico + piraclostrobina, fludioxonil + metalaxil-M + tiabendazol e fludioxonil + metalaxil-M não afetaram a produtividade da cultura, embora a massa seca de nódulos tenha sido reduzida em todos os ensaios. Abstract in english The aim of this study was to evaluate the effects of treatment of common bean seeds with different fungicides on the survival of strains of Rhizobium tropici (SEMIA 4077) and Rhizobium freirei (SEMIA 4080), as well as on plant nodulation and on crop yield. Two experiments were carried out in sterili [...] zed substrate, under greenhouse conditions and in the experimental field of Embrapa Western Agriculture, in Dourados, Mato Grosso do Sul State, in a typical Oxisol. The fungicides (active ingredients) used in the experiments were: (1) carbendazim + thiram (Product A), (2) carbendazim + thiram (Product B), (3) carboxin + thiram, (4) fludioxonil + metalaxyl-M, (5) fludioxonil + metalaxyl-M + thiabendazole, (6) fluazinam + methyl thiophanate, (7) fipronil + methyl thiophanate + pyraclostrobin, (8) chlorothalonil + methyl thiophanate. The survival of R. tropici strains inoculated in bean seeds was affected by the application of fungicides, especially contact fungicides. In addition, fungicide application led to a reduction in the nodulation of bean plants, especially for nodular mass, either in assays carried out on sterilized substrate, in a greenhouse, or in the field experiment, where grain yield reduction was also noted with the use of most evaluated fungicides. The fungicides that mostly affected grain yield were carbendazim + thiram (Product B) and carboxin + thiram. The products fipronil + thiophanate methyl + pyraclostrobin, fludioxonil + metalaxyl-M + thiabendazole and fludioxonil + metalaxyl-M did not affect the crop yield, although the dry weight of nodules was reduced in all trials.

  4. Resposta da cultura do feijoeiro à adubação nitrogenada e à inoculação com rizóbio Response of common bean crop to nitrogen fertilization and rhizobium inoculation

    Directory of Open Access Journals (Sweden)

    Rodrigo de Pelegrin

    2009-02-01

    Full Text Available O manejo adequado da adubação nitrogenada representa uma das principais dificuldades da cultura do feijoeiro (Phaseolus vulgaris L.. No entanto, a fixação biológica de nitrogênio é uma fonte alternativa de suprimento deste nutriente à cultura. O presente estudo teve como objetivo avaliar a resposta do feijoeiro à inoculação com rizóbio e ao parcelamento de fertilizante nitrogenado em termos de nodulação das plantas e produtividade de grãos da cultura, bem como a viabilidade econômica da aplicação de fertilizante nitrogenado e, ou, inoculação com rizóbio em feijoeiro. O experimento foi conduzido num Latossolo Vermelho distroférrico, em Dourados, MS. O delineamento experimental utilizado foi o de blocos casualizados, com seis repetições. Os sete tratamentos consistiram da aplicação parcelada de fertilizante nitrogenado em diferentes doses (0, 20, 40, 80 e 160 kg ha-1 de N como ureia na cultura do feijoeiro, cv. Pérola, além de controles com inoculação de Rhizobium tropici combinada ou não com aplicação de 20 kg ha-1 de N. A análise econômica foi efetuada considerando os custos da ureia e sua aplicação a lanço, além do custo do inoculante; os demais custos não foram considerados, por não haver diferença entre os diferentes tratamentos. Foram obtidos o acréscimo de produtividade, o custo de produção, o acréscimo da receita bruta e o acréscimo da receita líquida dos tratamentos, em relação à testemunha sem inoculação e sem adubação nitrogenada. Embora a nodulação das plantas não tenha sido alterada pelos tratamentos, verificou-se tendência de redução conforme o aumento da dose de N aplicada. A inoculação com rizóbio selecionado promoveu rendimentos de grãos de feijoeiros equivalentes à aplicação de 80 kg ha-1 de N. Quando acrescida da adubação com 20 kg ha-1 de N no plantio, a inoculação com rizóbio propiciou acréscimo de receita líquida semelhante à aplicação de 160 kg ha-1 de N e superior ao tratamento com a adubação de 20 kg ha-1 de N sem inoculação, evidenciando a sua importância para obtenção de maior rentabilidade na cultura do feijoeiro.Adequate management of nitrogen fertilizer is one of the main difficulties on common bean (Phaseolus vulgaris L. crop. However, the biological N2 fixation is an alternative source of N supply to this crop. This study had the purpose to evaluate the response of common bean to rhizobium inoculation and split application of N fertilizer in terms of plant nodulation and grain yield. Besides, this study aimed to evaluate the economic viability of using N fertilizer application and/or rhizobium inoculation on the plants. The experiment was carried out on a typic Haplustox in Dourados, Mato Grosso do Sul State. The experimental design was a completely randomized block with six replications. The seven treatments consisted of different levels of N fertilizer (0, 20, 40, 80, and 160 kg ha-1 N as urea applied to common bean, cultivar Pérola, and control treatments with R. tropici inoculation with or without application of 20 kg ha-1 N. In the economic analysis, the cost of urea, broadcast application, and cost of inoculant were taken into account. No other costs were considered since the treatments did not differ. Increases in grain yield, production cost, net and gross income, in relation to the control without inoculation and without nitrogen were obtained. The effect of inoculation of selected rhizobia on bean grain yield was similar to the application of 80 kg ha-1 N. When supplied with 20 kg ha-1 N at sowing, rhizobium inoculation increased grain yield and net income similarly to the application of 160 kg ha-1 N and more than the treatment of 20 kg ha-1 N without inoculant, which demonstrates the importance of the inoculant for an enhanced crop profitability.

  5. Cyclic-?-glucans of Rhizobium (Sinorhizobium) sp. strain NGR234 are required for hypo-osmotic adaptation, motility, and efficient symbiosis with host plants.

    Science.gov (United States)

    Gay-Fraret, Jérémie; Ardissone, Silvia; Kambara, Kumiko; Broughton, William J; Deakin, William J; Le Quéré, Antoine

    2012-08-01

    Cyclic-?-glucans (C?G) consist of cyclic homo-polymers of glucose that are present in the periplasmic space of many Gram-negative bacteria. A number of studies have demonstrated their importance for bacterial infection of plant and animal cells. In this study, a mutant of Rhizobium (Sinorhizobium) sp. strain NGR234 (NGR234) was generated in the cyclic glucan synthase (ndvB)-encoding gene. The great majority of C?G produced by wild-type NGR234 are negatively charged and substituted. The ndvB mutation abolished C?G biosynthesis. We found that, in NGR234, a functional ndvB gene is essential for hypo-osmotic adaptation and swimming, attachment to the roots, and efficient infection of Vigna unguiculata and Leucaena leucocephala. PMID:22583376

  6. Resposta da cultura do feijoeiro à adubação nitrogenada e à inoculação com rizóbio / Response of common bean crop to nitrogen fertilization and rhizobium inoculation

    Scientific Electronic Library Online (English)

    Rodrigo de, Pelegrin; Fábio Martins, Mercante; Ilda Miyuki Nakase, Otsubo; Auro Akio, Otsubo.

    2009-02-01

    Full Text Available O manejo adequado da adubação nitrogenada representa uma das principais dificuldades da cultura do feijoeiro (Phaseolus vulgaris L.). No entanto, a fixação biológica de nitrogênio é uma fonte alternativa de suprimento deste nutriente à cultura. O presente estudo teve como objetivo avaliar a resposta [...] do feijoeiro à inoculação com rizóbio e ao parcelamento de fertilizante nitrogenado em termos de nodulação das plantas e produtividade de grãos da cultura, bem como a viabilidade econômica da aplicação de fertilizante nitrogenado e, ou, inoculação com rizóbio em feijoeiro. O experimento foi conduzido num Latossolo Vermelho distroférrico, em Dourados, MS. O delineamento experimental utilizado foi o de blocos casualizados, com seis repetições. Os sete tratamentos consistiram da aplicação parcelada de fertilizante nitrogenado em diferentes doses (0, 20, 40, 80 e 160 kg ha-1 de N como ureia) na cultura do feijoeiro, cv. Pérola, além de controles com inoculação de Rhizobium tropici combinada ou não com aplicação de 20 kg ha-1 de N. A análise econômica foi efetuada considerando os custos da ureia e sua aplicação a lanço, além do custo do inoculante; os demais custos não foram considerados, por não haver diferença entre os diferentes tratamentos. Foram obtidos o acréscimo de produtividade, o custo de produção, o acréscimo da receita bruta e o acréscimo da receita líquida dos tratamentos, em relação à testemunha sem inoculação e sem adubação nitrogenada. Embora a nodulação das plantas não tenha sido alterada pelos tratamentos, verificou-se tendência de redução conforme o aumento da dose de N aplicada. A inoculação com rizóbio selecionado promoveu rendimentos de grãos de feijoeiros equivalentes à aplicação de 80 kg ha-1 de N. Quando acrescida da adubação com 20 kg ha-1 de N no plantio, a inoculação com rizóbio propiciou acréscimo de receita líquida semelhante à aplicação de 160 kg ha-1 de N e superior ao tratamento com a adubação de 20 kg ha-1 de N sem inoculação, evidenciando a sua importância para obtenção de maior rentabilidade na cultura do feijoeiro. Abstract in english Adequate management of nitrogen fertilizer is one of the main difficulties on common bean (Phaseolus vulgaris L.) crop. However, the biological N2 fixation is an alternative source of N supply to this crop. This study had the purpose to evaluate the response of common bean to rhizobium inoculation a [...] nd split application of N fertilizer in terms of plant nodulation and grain yield. Besides, this study aimed to evaluate the economic viability of using N fertilizer application and/or rhizobium inoculation on the plants. The experiment was carried out on a typic Haplustox in Dourados, Mato Grosso do Sul State. The experimental design was a completely randomized block with six replications. The seven treatments consisted of different levels of N fertilizer (0, 20, 40, 80, and 160 kg ha-1 N as urea) applied to common bean, cultivar Pérola, and control treatments with R. tropici inoculation with or without application of 20 kg ha-1 N. In the economic analysis, the cost of urea, broadcast application, and cost of inoculant were taken into account. No other costs were considered since the treatments did not differ. Increases in grain yield, production cost, net and gross income, in relation to the control without inoculation and without nitrogen were obtained. The effect of inoculation of selected rhizobia on bean grain yield was similar to the application of 80 kg ha-1 N. When supplied with 20 kg ha-1 N at sowing, rhizobium inoculation increased grain yield and net income similarly to the application of 160 kg ha-1 N and more than the treatment of 20 kg ha-1 N without inoculant, which demonstrates the importance of the inoculant for an enhanced crop profitability.

  7. Ultraviolet-irradiation induced and spontaneous mutation of Rhizobium trifolii 11B in relation to water-soluble and water-insoluble polysaccharide production ability

    International Nuclear Information System (INIS)

    Rhizobium trifolii 11B was u.v. irradiated and nine u.v. mutants have been isolated. Among the mutants, only one, R. trifolii 21M11B, produced more (752 mg/100 ml) water-soluble polysaccharide than the parent (704 mg/100 ml). The composition of water-soluble polysaccharide from u.v. mutants differed from that of the parent, R. trifolii 11B, and none of its u.v. mutants produced water-insoluble polysaccharide as detected by the Aniline Blue method. Storage of u.v. mutants for 2 months at 50C gave four spontaneous variants which acquired the ability to produce water-insoluble polysaccharide. The spontaneous mutants also retained their water-soluble polysaccharide producing ability. The water-soluble polysaccharide produced by these mutants was characterized as curdlan type. The chemistry of water-soluble and water-insoluble polysaccharides was also ascertained. (author)

  8. Effects of Different Strains of Rhizobium legominosarum biovar phaseoli on Yield and N2 Fixation Rate of Common Bean (Phaseolus vulgaris L. Iranian Cultivars

    Directory of Open Access Journals (Sweden)

    Abdollah Ghasemi Pirbalouti

    2006-01-01

    Full Text Available In order to evaluate of nitrogen biological fixation ability by different strains of Rhizobium legominosarum biovar phaseoli in common bean Iranian cultivars, a spilt plot experiment in randomized complete block design was conducted a field in Shahrekord, Iran. The factors were four bacterial strains: L-78, L-47, L-125, l-109, non-inoculated controls including application of nitrogen fertilizer treatment (100 kg N ha-1, without application of nitrogen fertilizer and three cultivars: local cranberry bean, Talash cranberry bean and local red type. The results showed that seed inoculation with strain increased nodule dry weight, N total (shoot and percentage of fixed N2 in relation to bean rhizobia population naturalized and +N control. However, an efficient symbiotic was achieved with strain L-109, since total N content of plants inoculated with these strains was similar to that of plants supplied with N-fertilizer treatment.

  9. Host-specific regulation of nodulation genes in Rhizobium is mediated by a plant-signal, interacting with the nodD gene product.

    Science.gov (United States)

    Horvath, B; Bachem, C W; Schell, J; Kondorosi, A

    1987-04-01

    We have identified a nodD gene from the wide host-range Rhizobium strain MPIK3030 (termed nodD1) which is essential for nodulation on Macroptilium atropurpureum (siratro). Experiments with nodA-lacZ gene fusions demonstrate that the MPIK3030 nodD1 regulates expression of the nodABC genes. Additionally, we used nodC-lacZ fusions of Rhizobium meliloti to show that the MPIK3030 nodD1 gene induces expression of these fusions by interacting with plant factors from siratro and from the non-host Medicago sativa (alfalfa). The R. meliloti nodD genes, however, only interact with alfalfa exudate. In line with these results, no complementation of MPIK3030 nodD1 mutants could be obtained on siratro with the R. meliloti nodD genes, while the MPIK3030 nodD1 can complement nodD mutants of R. meliloti on alfalfa. Furthermore, R. meliloti transconjugants harbouring the MPIK3030 nodD1 efficiently nodulate the illegitimate host siratro. When compared with other nodD sequences, the amino acid sequence of the MPIK3030 nodD1 shows a conserved aminoterminus, whereas the carboxy-terminus of the putative gene product diverges considerably. Studies on a chimeric MPIK3030/R. meliloti nodD gene indicates that the carboxy-terminal region is responsible for the interaction with plant factor(s) and may have evolved in different rhizobia specifically to interact with plant-host factors. PMID:16453758

  10. Uso de micorrizas e rizóbio em cultivo consorciado de eucalipto e sesbânia: II - Absorção e eficiência de utilização de fósforo e frações fosfatadas Use of mycorrhizas and rhizobium in intercropping system of eucalyptus and sesbania: II - Phosphorus uptake and efficiency of use and phosphate phosphate -fractions

    Directory of Open Access Journals (Sweden)

    L. A. Rodrigues

    2003-08-01

    Full Text Available Realizou-se um experimento em casa de vegetação com o objetivo de avaliar os efeitos de fungos micorrízicos arbusculares (FMAs e rizóbio na absorção e eficiência de utilização de P e nas frações fosfatadas em mudas de Eucalyptus grandis, cultivadas em consorciação com Sesbania virgata. Os tratamentos foram: inoculação ou não com FMAs em ambas as espécies de plantas e inoculação ou não com rizóbio na S. virgata, com quatro repetições. Ambas as plantas foram cultivadas em vasos de 6 L de capacidade, durante 100 dias, quando foram colhidas. A inoculação com FMAs ou FMAs + rizóbio aumentou o conteúdo de P no eucalipto, enquanto a inoculação com rizóbio, FMAs ou FMAs + rizóbio aumentou a eficiência de utilização de P. Nas frações de P, avaliadas nas folhas de eucalipto, observou-se aumento do fósforo total solúvel em ácido (PST nos tratamentos com inoculação de rizóbio ou FMAs + rizobio. Nos tratamentos com inoculação com rizóbio, FMAs, FMAs+rizóbio ou sem inoculação, observou-se que 81, 32, 91 e 68%, respectivamente, do PST foram encontrados como fósforo orgânico (Po. Em uma avaliação conjunta das frações fosfatadas e do conteúdo de P na parte aérea do eucalipto, o que aparentemente influenciou o aumento do PST e do Po não foi o conteúdo interno de P na planta, mas, sim, a inoculação do rizóbio na sesbânia.The effects of arbuscular mycorrhizal fungi (AMF and Rhizobium on P uptake and efficiency of use, as well as on the P fractions of Eucalyptus grandis grown in an intercropping system with Sesbania virgata were evaluated under greenhouse conditions. The treatments were: with or without inoculation with AMF of both plant species and with or without inoculation with Rhizobium of S. virgata plants only, in four replications. The two plant species were grown together in pots with a volume of 6 L for 100 days. Inoculations with AMF or with AMF + Rhizobium increased the P content in Eucalyptus plants, while inoculations with Rhizobium, AMF, or with AMF + Rhizobium increased the P utilization efficiency. An increase of total acid-soluble P (PTS in the treatments inoculated with Rhizobium or AMF + Rhizobium was observed in the P fractions of the analyzed Eucalyptus plant leaves. In the inoculation treatments with Rhizobium, AMF, and AMF + Rhizobium, and the control (uninoculated 81, 32, 91, and 68%, respectively, of the PST in the leaves of Eucalyptus plants were found in organic-P (Po form. An evaluation of both the P fractions and P contents of Eucalyptus shoots suggests that the increase of PST and organic-P was caused by the inoculation of Rhizobium in sesbania plants, and not by the internal P plant content.

  11. 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...

  12. Characterization and functional analysis of seven flagellin genes in Rhizobium leguminosarum bv. viciae. Characterization of R. leguminosarum flagellins

    Directory of Open Access Journals (Sweden)

    Tambalo Dinah D

    2010-08-01

    Full Text Available Abstract Background Rhizobium leguminosarum bv. viciae establishes symbiotic nitrogen fixing partnerships with plant species belonging to the Tribe Vicieae, which includes the genera Vicia, Lathyrus, Pisum and Lens. Motility and chemotaxis are important in the ecology of R. leguminosarum to provide a competitive advantage during the early steps of nodulation, but the mechanisms of motility and flagellar assembly remain poorly studied. This paper addresses the role of the seven flagellin genes in producing a functional flagellum. Results R. leguminosarum strains 3841 and VF39SM have seven flagellin genes (flaA, flaB, flaC, flaD, flaE, flaH, and flaG, which are transcribed separately. The predicted flagellins of 3841 are highly similar or identical to the corresponding flagellins in VF39SM. flaA, flaB, flaC, and flaD are in tandem array and are located in the main flagellar gene cluster. flaH and flaG are located outside of the flagellar/motility region while flaE is plasmid-borne. Five flagellin subunits (FlaA, FlaB, FlaC, FlaE, and FlaG are highly similar to each other, whereas FlaD and FlaH are more distantly related. All flagellins exhibit conserved amino acid residues at the N- and C-terminal ends and are variable in the central regions. Strain 3841 has 1-3 plain subpolar flagella while strain VF39SM exhibits 4-7 plain peritrichous flagella. Three flagellins (FlaA/B/C and five flagellins (FlaA/B/C/E/G were detected by mass spectrometry in the flagellar filaments of strains 3841 and VF39SM, respectively. Mutation of flaA resulted in non-motile VF39SM and extremely reduced motility in 3841. Individual mutations of flaB and flaC resulted in shorter flagellar filaments and consequently reduced swimming and swarming motility for both strains. Mutant VF39SM strains carrying individual mutations in flaD, flaE, flaH, and flaG were not significantly affected in motility and filament morphology. The flagellar filament and the motility of 3841 strains with mutations in flaD and flaG were not significantly affected while flaE and flaH mutants exhibited shortened filaments and reduced swimming motility. Conclusion The results obtained from this study demonstrate that FlaA, FlaB, and FlaC are major components of the flagellar filament while FlaD and FlaG are minor components for R. leguminosarum strains 3841 and VF39SM. We also observed differences between the two strains, wherein FlaE and FlaH appear to be minor components of the flagellar filaments in VF39SM but these flagellin subunits may play more important roles in 3841. This paper also demonstrates that the flagellins of 3841 and VF39SM are possibly glycosylated.

  13. A Rhizobium tropici DNA region carrying the amino-terminal half of a nodD gene and a nod-box-like sequence confers host-range extension.

    Science.gov (United States)

    Sousa, C; Folch, J L; Boloix, P; Megías, M; Nava, N; Quinto, C

    1993-09-01

    Rhizobium tropici CIAT899 is a broad-host-range strain that, in addition to Phaseolus, nodulates other plant legumes such as Leucaena and Macroptilium. The narrow-host-range of Rhizobium leguminosarum biovars phaseoli (strain CE3) and trifolii (strain RS1051) can be extended to Leucaena esculenta and Phaseolus vulgaris plants, respectively, by the introduction of a DNA fragment 521 bp long, which carries 128 amino acids of the amino-terminal region of a nodD gene from R. tropici, as well as a putative nod-box-like sequence, divergently oriented. The 521 bp fragment, in the presence of L. esculenta or P. vulgaris root exudates, induced a R. leguminosarum bv. viciae nodA-lacZ fusion in either a CE3 or RS1051 background, respectively. PMID:7934929

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

    International Nuclear Information System (INIS)

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

  15. Effects of Different Strains of Rhizobium legominosarum biovar phaseoli on Yield and N2 Fixation Rate of Common Bean (Phaseolus vulgaris L.) Iranian Cultivars

    OpenAIRE

    Abdollah Ghasemi Pirbalouti; Iraj Allahdadi; Gholam Abbas Akbari; Ahamd Reza Golparvar; Safar Ali Rostampoor

    2006-01-01

    In order to evaluate of nitrogen biological fixation ability by different strains of Rhizobium legominosarum biovar phaseoli in common bean Iranian cultivars, a spilt plot experiment in randomized complete block design was conducted a field in Shahrekord, Iran. The factors were four bacterial strains: L-78, L-47, L-125, l-109, non-inoculated controls including application of nitrogen fertilizer treatment (100 kg N ha-1), without application of nitrogen fertilizer and three cultivars: local cr...

  16. 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

  17. Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Gurney, Kevin R

    2015-01-12

    This document constitutes the final report under DOE grant DE-FG-08ER64649. The organization of this document is as follows: first, I will review the original scope of the proposed research. Second, I will present the current draft of a paper nearing submission to Nature Climate Change on the initial results of this funded effort. Finally, I will present the last phase of the research under this grant which has supported a Ph.D. student. To that end, I will present the graduate student’s proposed research, a portion of which is completed and reflected in the paper nearing submission. This final work phase will be completed in the next 12 months. This final workphase will likely result in 1-2 additional publications and we consider the results (as exemplified by the current paper) high quality. The continuing results will acknowledge the funding provided by DOE grant DE-FG-08ER64649.

  18. Final Report

    Energy Technology Data Exchange (ETDEWEB)

    DeTar, Carleton [P.I.

    2012-12-10

    This document constitutes the Final Report for award DE-FC02-06ER41446 as required by the Office of Science. It summarizes accomplishments and provides copies of scientific publications with significant contribution from this award.

  19. 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.

  20. 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.

  1. La balle et la plume

    Directory of Open Access Journals (Sweden)

    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...

  2. 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...

  3. 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.

  4. Entrepreneuriat Social et Participation Citoyenne

    Directory of Open Access Journals (Sweden)

    Sophie Larivet

    2010-01-01

    Full Text Available L'entrepreneuriat social est un concept émergeant, notamment dans les sciences de l'administration. Pourtant, en dehors d'une pratique directoriale spécifique, il est aussi une forme de participation citoyenne trop méconnue. L'objectif de cet article, basé sur une revue de la littérature et une approche théorique, est de présenter le concept d'entrepreneuriat social afin de mieux saisir son positionnement par rapport à la participation citoyenne. L'entrepreneuriat social constitue une forme particulière de participation à l'espace public par l'action, les entreprises sociales agissant au quotidien pour transformer le paysage social. En particulier, cet article souligne le contexte de développement de l'entrepreneuriat social, définit le concept et les notions connexes d'entreprise sociale et d'entrepreneur social, et, enfin, présente une réflexion sur la contribution de l'entrepreneuriat social à la participation citoyenne. L'article montre que l'entrepreneuriat social est une façon pour les citoyens d'agir directement et avec maîtrise sur la société. / Social entrepreneurship is an emerging concept, notably in administrative sciences. However, not only is it a specific managerial practice but it is also a type of citizen participation that is not well-known. The objective of this article, based on a literature review and a theoretical approach, is to present the concept of social entrepreneurship in order to better understand its relation to citizen participation. Social entrepreneurship represents a specific type of citizen participation involving actions. Social enterprises act daily to transform the social landscape. More specifically, this article presents the context of development of social entrepreneurship, proposes a definition of the concept and of other connected notions like "social enterprise" and "social entrepreneur", and, finally, analyzes the contribution of social entrepreneurship to citizen participation. It shows that social entrepreneurship is a way for citizens to act directly and with some power on society.

  5. L’excellence : impossible sans un personnel stable et expérimenté

    CERN Multimedia

    Association du personnel

    2013-01-01

    Le monde entier avait les yeux fixés sur le CERN ce 4 juillet 2012, quand ATLAS et CMS ont annoncé leur découverte d’une particule « compatible avec le Higgs ». Début 2013 il n’a fallu que quelques jours pour régler le LHC et faire tourner des protons et des ions lourds. Toutes ces découvertes et prouesses techniques n’ont été possibles que grâce à l’expérience et la poursuite de l’excellence d’équipes soudées de techniciens et ingénieurs qui ont conçu, construit, mis en marche, et finalement font fonctionner ce complexe d’accélérateurs unique au monde. Un service d’excellence avec un encadrement adéquat Entre 2002 et 2012 (voir Fig. 1), le nombre d’utilisateurs est passé de 5912 à...

  6. 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.

  7. Culture science et économie

    OpenAIRE

    Caro, Paul

    2004-01-01

    Pour que les dépenses de recherche et de développement atteignent 3% du PIB en Europe en 2010, il est nécessaire de créer un courant d'intérêt pour les sciences et les techniques, notamment chez les jeunes. Mais cela dépend beaucoup du climat culturel et intellectuel comme le montre l'histoire du prodigieux développement des sciences en Europe depuis le XVIIème siècle. Ce climat, dans nos sociétés dominées par le spectacle, est en partie créé et manipulé par les media. Media et industriels du...

  8. Integrated use of Rhizobium leguminosarum, Plant Growth Promoting Rhizobacteria and Enriched Compost for Improving Growth, Nodulation and Yield of Lentil (Lens culinaris Medik.) / Uso Integrado de Rhizobium leguminosarum, Rizobacterias Promotoras de Crecimiento Vegetal y Compost Enriquecido para Mejorar el Crecimiento, Nodulación y Rendimiento de Lenteja (Lens culinaris Medik.)

    Scientific Electronic Library Online (English)

    Muhammad Asif, Iqbal; Muhammad, Khalid; Sher Muhammad, Shahzad; Maqshoof, Ahmad; Nawaf, Soleman; Naeem, Akhtar.

    2012-03-01

    Full Text Available La mantención de una alta población bacteriana en la rizósfera mejora la eficiencia de estos organismos. Esta población bacteriana puede ser mantenida por la aplicación de compost enriquecido que mantiene su crecimiento y actividades. Por lo tanto, el uso integrado de Rhizobium, rhizobacterias promo [...] toras de crecimiento vegetal (PGPR) conteniendo 1-aminociclopropano-1-carboxilato desaminasa (ACC-desaminasa) y compost enriquecido con P (PEC) podría ser altamente efectivo en la promoción de crecimiento, nodulación, y producción de lenteja (Lens culinaris Medik.). Un estudio de campo se condujo para evaluar el potencial de Rhizobium, PGPR conteniendo ACC-desaminasa y PEC para promover el crecimiento de lenteja. Para este estudio, el tipo de suelo fue franco-arcillo arenoso con pH 7,6; conductividad eléctrica 2,8 dS m-1; materia orgánica 0,59%; N total 0,032%; P disponible 7,9 mg kg-1, y K extraíble 129 mg kg-1. Los tratamientos se repitieron tres veces, usando diseno de bloques completos al azar. Los resultados mostraron que el uso integrado de R. leguminosarum con Pseudomonas spp. conteniendo ACC-desaminasa junto con PEC fue altamente efectivo y causaron hasta 73.5, 73.9, 74.4, 67.5, 73.3, 65.8, 40.5, y 52.5% de aumento en biomasa fresca, producción de grano, producción de paja, vainas planta-1, peso seco de nódulo por planta, peso de 1000 granos, y contenido de N en grano de lenteja, respectivamente, comparado con el respectivo control. Se concluyó que el uso integrado de R. leguminosarum con Pseudomonas spp. portando el rasgo de ACC-desaminasa más PEC podría ser un apronte efectivo para mejor nodulación que consecuentemente mejoró producción de lenteja bajo condiciones naturales. Abstract in english Maintenance of high bacterial population in the rhizosphere improves the efficiency of these organisms. This high bacterial population can be maintained by the application of enriched compost which supports their growth and activities. Thus integrated use of Rhizobium, plant growth promoting rhizoba [...] cteria (PGPR) containing 1-aminocyclopropane-1-carboxylate deaminase (ACC-deaminase) and P-enriched compost (PEC) could be highly effective for promoting growth, nodulation, and yield of lentil (Lens culinaris Medik.). A field study was conducted to evaluate the potential of Rhizobium, PGPR containing ACC-deaminase and PEC for promoting growth of lentil. For this study, the soil type was sandy clay loam soil having pH 7.6; EC (electrical conductivity) 2.8 dS m-1; organic matter (OM) 0.59%; total N 0.032%; available P 7.9 mg kg-1, and extractable K 129 mg kg-1. Treatments were replicated thrice, using randomized complete block (RCB) design. Results showed that the integrated use of R. leguminosarum with Pseudomonas spp. containing ACC-deaminase along with PEC was highly effective and caused up to 73.5, 73.9, 74.4, 67.5, 73.3, 65.8, 40.5, and 52.5% increase in fresh biomass, grain yield, straw yield, pods plant-1, nodule plant-1, nodule dry weight plant-1, 1000-grain weight, and N content in grain of lentil, respectively, as compared to respective control. It is concluded that integrated use of R. leguminosarum with Pseudomonas spp. having trait ACC-deaminase plus PEC would be an effective approach for better nodulation which consequently improved yield of lentil under natural conditions.

  9. 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)

  10. Evaluación de la fertilización biológica del frijol con cepas nativas de Rhizobium aisladas de un ultisol de la altiplanicie del estado guarico / Evaluation of the biological fertilization on cowpea with nativa Rhizobium strains isoleted from an ultisol in landplane guarico state

    Scientific Electronic Library Online (English)

    Belkys, Rodríguez; Marisol, López.

    2009-12-01

    Full Text Available Se evaluó el efecto de la fertilización biológica en frijol, Vigna unguiculata L., con cepas nativas de Rhizobium aisladas de un Ultisol de la altiplanicie en condiciones de mesa del estado Guárico sobre la producción de materia seca (MS), porcentaje de nódulos (PN), masa nodular (MN), actividad nod [...] ular, (AN), absorción de nitrógeno (N) y absorción de fósforo (P), en condiciones de invernadero. Los tratamientos evaluados fueron: sin biofertilizante, biofertilización con la cepa 1, biofertilización con cepa 2 y biofertilización con una combinación de las cepas 1 y 2, conjuntamente con la aplicación de una fertilización basal de N, P y K reducida, obteniéndose a partir de las variables medidas que la cepa 1 mostró una alta capacidad para colonizar el cultivo, lo cual la convierte en el biofertilizante con mayor potencial para gestionar la fertilización del frijol en los conucos llaneros presentes en la altiplanicie Abstract in english The effect of biological fertilization on cowpea, Vigna unguiculata L., with native Rhizobium strains isolated from an ultisol in landplane condition of Guárico state, Venezuela, was evaluated on dry matter production (MS), nodules percentage (PN), nodular mass (MN), nodular activity (AN), nitrogen [...] uptake (N) and phosphorus uptake (P), in an experiment carried out in greenhouse conditions. The evaluated treatments were: without biofertilization (control), biofertilization with strain 1, biofertilization with strain 2 and biofertilization with consortium strains 1 + 2, jointly with the application of a reduced basal fertilization of N, P and K. the strain1 showed high capacity to colonize the crop, which turn it into biological fertilizer with the greatest potential to manage cowpea fertilization in llaneros homegarden in landplane conditions

  11. 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...

  12. 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...

  13. 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)

  14. Complete genome sequence of Rhizobium leguminosarum bv trifolii strain WSM2304, an effective microsymbiont of the South American clover Trifolium polymorphum

    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; Malfatti, Stephanie [Lawrence Livermore National Laboratory (LLNL); Kiss, Hajnalka [Los Alamos National Laboratory (LANL); Lapidus, Alla L. [U.S. Department of Energy, Joint Genome Institute; Copeland, A [U.S. Department of Energy, Joint Genome Institute; Nolan, Matt [U.S. Department of Energy, Joint Genome Institute; Land, Miriam L [ORNL; 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 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 WSM2304, together with the complete genome sequence, and annotation. This is the first completed genome sequence for a nitrogen fixing microsymbiont of a clover species from the American center of origin. We reveal that its genome size is 6,872,702 bp encoding 6,643 protein-coding genes and 62 RNA only encoding genes. This multipartite genome was found to contain 5 distinct replicons; a chromosome of size 4,537,948 bp and four circular plasmids of size 1,266,105 bp, 501,946 bp, 308,747 bp and 257,956 bp.

  15. Recovery of development and functionality of nodules and plant growth in salt-stressed Pisum sativum--Rhizobium leguminosarum symbiosis by boron and calcium.

    Science.gov (United States)

    Bolaños, Luis; El-Hamdaoui, Abdelaziz; Bonilla, Ildefonso

    2003-12-01

    Nodules developed in Pisum sativum L. cv. Argona inoculated with Rhizobium leguminosarum bv. viciae 3841 and growing under saline conditions (75 mmol/L NaCl) are non functional and had abnormal structure. The infected cells contained a low amount of endophytic bacteria, compared to treatments without salt. Addition of B (up to 55.8 micromol/L) and Ca2+ (up to 2.72 mmol/L) increased bacterial population of host plant cells in salt-stressed nodules. Furthermore, symbiosomes developed inside the nodules from salt treated plants presented a degraded peribacteroid membrane. This effect was also prevented by combined addition of B and Ca2+. Given the importance of both nutrients in cell wall structure, the pectin fraction was studied by electron microscopy and immunological methods. Salt stress produced cells with walls dramatically altered or even degraded in several zones. Pectin polysaccharides, detected by JIM 5 monoclonal antibody, increased in cells under salinity. These effects resembled typical effects of B-deficiency reactions in cell walls, and the increase of both Ca2+ and especially B also prevented these alterations. PMID:14717443

  16. Bacillus simplex—A Little Known PGPB with Anti-Fungal Activity—Alters Pea Legume Root Architecture and Nodule Morphology When Coinoculated with Rhizobium leguminosarum bv. viciae

    Directory of Open Access Journals (Sweden)

    Ann M. Hirsch

    2013-09-01

    Full Text Available Two strains, 30N-5 and 30VD-1, identified as Bacillus simplex and B. subtilis, were isolated from the rhizospheres of two different plants, a Podocarpus and a palm, respectively, growing in the University of California, Los Angeles (UCLA Mildred E. Mathias Botanical Garden. B. subtilis is a well-known plant-growth promoting bacterial species, but B. simplex is not. B. simplex 30N-5 was initially isolated on a nitrogen-free medium, but no evidence for nitrogen fixation was found. Nevertheless, pea plants inoculated with B. simplex showed a change in root architecture due to the emergence of more lateral roots. When Pisum sativum carrying a DR5::GUSA construct, an indicator for auxin response, was inoculated with either B. simplex 30N-5 or its symbiont Rhizobium leguminosarum bv. viciae 128C53, GUS expression in the roots was increased over the uninoculated controls. Moreover, when pea roots were coinoculated with either B. simplex 30N-5 or B. subtilis 30VD-1 and R. leguminosarum bv. viciae 128C53, the nodules were larger, clustered, and developed more highly branched vascular bundles. Besides producing siderophores and solubilizing phosphate, the two Bacillus spp., especially strain 30VD-1, exhibited anti-fungal activity towards Fusarium. Our data show that combining nodulating, nitrogen-fixing rhizobia with growth-promoting bacteria enhances plant development and strongly supports a coinoculation strategy to improve nitrogen fixation, increase biomass, and establish greater resistance to fungal disease.

  17. Formulation of microbes inoculum: AMF, PSB and Rhizobium isolated of ex-coal mining site for Acacia crassicarpa Cunn. Ex-benth seedlings

    Directory of Open Access Journals (Sweden)

    ENNY WIDYATI

    2007-07-01

    Full Text Available The shoddier succeed land revegetation particularly caused by least adaptability of the seedlings planted on this site. To encourage their growth and survival rate it can be achieved by means do inoculation with the compatible functional microbes such as rhizobium, Psolubilizing bacteria (PSB and/or arbuscular-mycorrhiza fungy (AMF. This reserach is aimed to formulate the most compatible inoculant to support the growth of A. crassicarpa seedlings. Compatibility study is carried out in RCB design with 3 replications, each contain 5 seedlings. Height and biomass are accessed to measure the growth responses of the seedlings. The result showed that the best reponse is given by consortia that consist of the three kinds of these microbes. This increase the shoot biomass (137% compare to the control. The consortia also improved N 164%, P 335% and K 167% in the plant tissues. While pure AMF improved absorption of N plants 80%, P 383% and K 51% compare to the control. It is suggested that to prepare the A. crassicarpa seedlings is better inoculated by consortium of microbes or AMF as a sole inoculant.

  18. The Inhibition of Bean Plant Metabolism by Cadmium Metal: I Effect of Cd Metal on Physiological Process of Bean Plant and Rhizobium Species

    Directory of Open Access Journals (Sweden)

    Rafia Azmat

    2005-01-01

    Full Text Available Toxicity of Cadmium (Cd metal were determined by the absorption and accumulation in bean plants. Results have been explained in relation with nitrifying bacteria and physiological process of plants. Toxicity of heavy metal Cd mainly due to the industrial wastage, medicinal pesticides, automobile exhaust which were continuously thrown in aquatic resources, causes contamination of water used for irrigation. It was observed that Cd seems to be highly toxic to the seedlings of bean plants at all concentration used and it was also harmful for the microbial life of soil. No nodule formation in the roots of bean plants were found, due to the lower population of soil bacteria, which fixes the nitrogen from the atmosphere in to the roots of plant in the form of nodules. Physiological processes of plants were effected by the absence of nitrifying bacteria, Rhizobium species. Protein and amino acid contents were found to be decreased at low concentration of Cd, but amino acid were absent at high percentage of Cd metal. Morphology of plants were also inflected by the presence of metal and color of plants turns yellow which in turns produce the effect on process of photosynthesis.

  19. Bacteria-zinc co-localization implicates enhanced synthesis of cysteine-rich peptides in zinc detoxification when Brassica juncea is inoculated with Rhizobium leguminosarum.

    Science.gov (United States)

    Adediran, Gbotemi A; Ngwenya, Bryne T; Mosselmans, J Frederick W; Heal, Kate V

    2016-01-01

    Some plant growth promoting bacteria (PGPB) are enigmatic in enhancing plant growth in the face of increased metal accumulation in plants. Since most PGPB colonize the plant root epidermis, we hypothesized that PGPB confer tolerance to metals through changes in speciation at the root epidermis. We employed a novel combination of fluorophore-based confocal laser scanning microscopic imaging and synchrotron based microscopic X-ray fluorescence mapping with X-ray absorption spectroscopy to characterize bacterial localization, zinc (Zn) distribution and speciation in the roots of Brassica juncea grown in Zn contaminated media (400 mg kg(-1) Zn) with the endophytic Pseudomonas brassicacearum and rhizospheric Rhizobium leguminosarum. PGPB enhanced epidermal Zn sequestration relative to PGBP-free controls while the extent of endophytic accumulation depended on the colonization mode of each PGBP. Increased root accumulation of Zn and increased tolerance to Zn was associated predominantly with R. leguminosarum and was likely due to the coordination of Zn with cysteine-rich peptides in the root endodermis, suggesting enhanced synthesis of phytochelatins or glutathione. Our mechanistic model of enhanced Zn accumulation and detoxification in plants inoculated with R. leguminosarum has particular relevance to PGPB enhanced phytoremediation of soils contaminated through mining and oxidation of sulphur-bearing Zn minerals or engineered nanomaterials such as ZnS. PMID:26263508

  20. Contribution of applied and soil phosphorus and sulphur in chickpea (Cicer arietinum L.) as influenced by Fe and Rhizobium inoculation in a Typic haplustept

    International Nuclear Information System (INIS)

    In an experiment with a test crop of chickpea during rabi, 1999-2000 the influence of P, S and Fe on the uptake of P and S was assessed using isotopic tracers (32P and 35S). It was found that the dry matter production increased by the application of phosphorus at 60 kg P2O5 ha-1 in both with and without Rhizobium inoculation and the combined application of P and Fe produced higher dry matter of both shoot and roots with inoculation. An assessment of the radioassay of applied phosphate and sulphate showed lower values of per cent derived from fertilizer in respect of both P and S. However, the values of phosphorus derived from fertilizer (Pdff) were comparatively higher due to combined application of P, S and Fe and those for sulphur due to phosphorus and sulphur only. The contribution of phosphorus from soil was more due to combined application of phosphorus and sulphur against the inoculation treatment, whereas, the contribution of phosphorus from fertilizer was observed to be improved due to applied phosphorus and iron along with the inoculation. Contribution of soil source for sulphur uptake increased with the application of sulphur along with iron or phosphorus both with and without inoculation. (author)

  1. UV-radiation induced changes in antibiotic markers, chemical composition of water soluble polysaccharides and nodulation ability of Rhizobium trifolic 11B

    International Nuclear Information System (INIS)

    Rhizobium trifolii 11B, which formed effective nodules on its host. Trifolium alexanderinum L. was UV-irradiated to isolate mutants. Out of the 9 variants isolated only 1 strain, viz. 21M11B produced more water soluble polysaccharide [752 mg (100 ml-1)] than the parent 15 different antibiotics was similar only in two (22M11B and 26M11B) of the 9 UV-mutants. Compositional studies revealed that the water soluble polysaccharides from all strains contained glucose and galactose in the molar ratio of 7:1. Glucuronic acid which was present (2.33 per cent) in the water soluble polysaccharide from strain 11B was absent in all but 2UV-mutants (4.22per cent in 6M11B and 4.04per cent in26M11B). Five of the UB-mutants (1M11B, 17M11B, 20N11B, 22M11B and 26M11B) were Nod-. The organisms which produced more water soluble polysaccharide upon infection of the plants induced the formation of more number of nodules. (author)

  2. 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.

  3. 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...

  4. 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

  5. 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.

  6. 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.

  7. FINAL REPORT

    Energy Technology Data Exchange (ETDEWEB)

    Lettenmaier, Dennis [University of Washsington

    2012-05-26

    We proposed to extend Maurer’s data sets through at least 2005 (to include extreme drought years in the Colorado basin). We updated and verified the forcings for tmin, tmax, and precipitation over the Colorado River basin at 1/8-deg spatial resolution through November 2008, with the potential to alter the resolution as needed (we subsequently extended the Maurer et al data set over the entire continental U.S. at 1/16 degree spatial resolution; see Livneh et al., 2013). We proposed to use either MODIS-based land cover data for recent years, or modification of the existing fixed seasonal cycle used in VIC (based on University of Maryland land cover data) to represent interannual variations in vegetation characteristics such as leaf area index (LAI) particularly in drought years. We assessed model performance with respect to evapotranspiration estimation through comparison of the model predictions with ground observations and in experiments that use time-varying and fixed seasonal LAI cycles (based on University of Maryland land cover data) in a test region of northwestern Mexico where the ground ET observations from eddy covariance tower sites are available for the period from 2001 to 2008 (Tang et al., 2011). We also proposed to implement statistical downscaling with an adjustment to constrain precipitation changes at the GCM level. These simulations were performed, using 20 IPCC AR4 GCMs over the Colorado River basin with two global emissions scenarios, and are reported in Vano et al., 2014. Task 2: Coupled model implementation We proposed to implement the “standard” climate version of WRF, as used by collaborator Ruby Leung in NARCCAP simulations (see Section 5.4), and perform tests to assure that model output for runs equivalent to NARCCAP Phase 1 (reanalysis boundary conditions) are consistent. We proposed do test sensitivity to higher spatial resolution. We made a run of 11 years’ length with the “standard” version of WRF, forced by NCEP/DOE with the same spatial resolution as WRF in NARCCAP, with a slightly different domain designed to cover the Colorado River basin. We also compared the sensitivity of standard WRF simulations to different spatial resolutions (50 km, 25 km and 16 km). We proposed to implement the WRF-VIC version, and to evaluate differences between the “standard” WRF version (with CLM as the land scheme) and WRF-VIC. As part of a companion project (Regional Arctic Climate Model; RACM), we have linked the macroscale hydrologic model VIC (Variable Infiltration Capacity) with WRF through the CCSM coupling architecture CPL7. We decided to defer making new model runs with VIC over the Colorado basin and rather to focus on analysis of NARCCAP results. Our preliminary results from analysis of NARCCAP current and future climate results (reported in Gao et al., 2011) indicate that CRCM has a cold bias; HRM3 has a warm bias; and ECPC and CRCM have a wet bias over the Colorado River basin. Task 3: Retrospective coupled model simulations We proposed to compare the climatology of key land surface and atmospheric variables from the retrospective RCM and GCM runs, as well as 1/8-degree as the historical North American Land Data Assimilation System dataset (Maurer et al., 2002) to evaluate the ability of each of the RCMs and GCMs to reproduce characteristics of observed climate. In addition to the NARCCAP runs analyzed under Task 2, we also evaluated an ECHAM5/WRF run performed by Eric Salathe and HadCM3/WRF run performed by Francina Dominguez (University of Arizona). Results of the retrospective RCM runs indicate that they capture the primary features of the observed land–surface water budget and surface temperature better than their host GCMs. Although the RCMs do not have significantly improved simulations of precipitation relative to the GCMs, their ability to better represent surface temperature in mountainous regions has important effects on simulations of evapotranspiration, snowpack, and runoff. This improved skill in simulating temperature is important for detecting climate change signals

  8. Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Bauer, Susanne

    2015-02-09

    We participated in a FASTER SCM intercomparison for which we ran our SCM for 3 years at the SGP to analyze statistics of the precipitation field (Song et al., 2013). An important feature of these simulations was the use of relaxation forcing to observed T, q, which decouples the model convection from the forcing and allows precipitation errors to emerge. Because the GISS cumulus parameterization includes a trigger that prevents convection until sufficient lifting is present, and because convection at the SGP is usually triggered by mesoscale motions that are not represented in the forcing when relaxation is applied, the duration of SCM precipitation is shorter than observed (Del Genio and Wolf, 2012) and thus its mean precipitation less than observed. However, its diurnal cycle phase is correct, and it is the only operational cumulus parameterization in the intercomparison that does not produce excessive warm season precipitation under weak large-scale forcing conditions.

  9. 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.

  10. Transport optimal et irrigation

    OpenAIRE

    Bernot, Marc

    2005-01-01

    L'objet de cette thèse est de modéliser et d'étudier des structures d'irrigation telles les nervures des feuilles, réseau sanguin, poumons,etc. Un modèle généralisant le problème de Gilbert Steiner est introduit ; on étudie alors les propriétés d'existence, de stabilité et régularité. Des algorithmes sont alors proposés pour la simulation.

  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. Radioprotection et ingénierie nucléaire

    CERN Document Server

    2006-01-01

    Le développement de l'énergie nucléaire repose sur deux piliers essentiels : la sûreté nucléaire, qui concerne la machine, et la radioprotection, qui se préoccupe des hommes. Construit de manière fiable, un réacteur nucléaire se doit d'irradier le moins possible ses opérateurs et conduire à un impact très faible pour les populations avoisinantes. Tout cela est soumis à des règles strictes, élaborées au niveau international, et qui ne tolèrent aucun écart. Les ingénieurs qui ont à concevoir, construire et conduire ces machines doivent maîtriser les règles de protection : cet ouvrage leur est destiné. La radioprotection, si elle se fonde principalement sur des bases scientifiques, intègre également une dimension sociétale exigeante. Ces activités sont en effet sous le regard critique et permanent de nos concitoyens, qui exigent des acteurs de cette industrie une maîtrise totale de la radioprotection ; un ingénieur qui ne connaîtrait pas la genèse de la radioprotection, ses règle...

  13. 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.

  14. Induction of pathogenic-like responses in the legume Macroptilium atropurpureum by a transposon-induced mutant of the fast-growing, broad-host-range Rhizobium strain NGR234.

    OpenAIRE

    Djordjevic, S. P.; Ridge, R W; Chen, H. C.; Redmond, J.W.; Batley, M.; Rolfe, B.G.

    1988-01-01

    Mutant strain ANU2861, a transposon Tn5 mutant of the fast-growing, broad-host-range Rhizobium strain ANU280 (NGR234 Smr Rfr) overproduces polysaccharide, is an ade auxotroph, and induces poorly developed nodules on Leucaena leucocephala and Lablab purpureus (H.C. Chen, M. Batley, J.W. Redmond, and B.G. Rolfe, J. Plant Physiol. 120:331-349, 1985). Strain ANU2861 cannot form nodules on Macroptilium atropurpureum Urb. (siratro) or on Desmodium intortum and D. uncinatum and the nonlegume Paraspo...

  15. 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.

  16. 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.

  17. 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.

  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. 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...

  20. Artaud et les Tarahumaras

    Directory of Open Access Journals (Sweden)

    Marta Mariasole Raimondi

    2008-01-01

    Full Text Available Ce film propose des scènes de vie des Tarahumaras, une ethnie originaire du Mexique installée dans le territoire de l'Etat de Chiuahua, dans un milieu montagneux très sauvage. La caméra reprend les danses et les rites de ces mangeurs de peyotl d'un regard rapide et saccadé primant des cadrages de détail où prédominent les pieds, pour nous montrer ces corps d'homme et de femme en mouvement, courant, dansant, bondissant au milieu des leurs éléments naturels : rocailles, rivières, rochers, sans...

  1. The vbs genes that direct synthesis of the siderophore vicibactin in Rhizobium leguminosarum: their expression in other genera requires ECF sigma factor RpoI.

    Science.gov (United States)

    Carter, R A; Worsley, P S; Sawers, G; Challis, G L; Dilworth, M J; Carson, K C; Lawrence, J A; Wexler, M; Johnston, A W B; Yeoman, K H

    2002-06-01

    A cluster of eight genes, vbsGSO, vbsADL, vbsC and vbsP, are involved in the synthesis of vicibactin, a cyclic, trihydroxamate siderophore made by the symbiotic bacterium Rhizobium leguminosarum. None of these vbs genes was required for symbiotic N2 fixation on peas or Vicia. Transcription of vbsC, vbsGSO and vbsADL (but not vbsP) was enhanced by growth in low levels of Fe. Transcription of vbsGSO and vbsADL, but not vbsP or vbsC, required the closely linked gene rpoI, which encodes an ECF sigma factor of RNA polymerase. Transfer of the cloned vbs genes, plus rpoI, to Rhodobacter, Paracoccus and Sinorhizobium conferred the ability to make vicibactin on these other genera. We present a biochemical genetic model of vicibactin synthesis, which accommodates the phenotypes of different vbs mutants and the homologies of the vbs gene products. In this model, VbsS, which is similar to many non-ribosomal peptide synthetase multienzymes, has a central role. It is proposed that VbsS activates L-N5-hydroxyornithine via covalent attachment as an acyl thioester to a peptidyl carrier protein domain. Subsequent VbsA-catalysed acylation of the hydroxyornithine, followed by VbsL-mediated epimerization and acetylation catalysed by VbsC, yields the vicibactin subunit, which is then trimerized and cyclized by the thioesterase domain of VbsS to give the completed siderophore. PMID:12028377

  2. Activation of Rhizobium tibeticum with flavonoids enhances nodulation, nitrogen fixation, and growth of fenugreek (Trigonella foenum-graecum L.) grown in cobalt-polluted soil.

    Science.gov (United States)

    Abd-Alla, Mohamed Hemida; Bagy, Magdy Khalil; El-enany, Abdel-Wahab El-sadek; Bashandy, Shymaa Ryhan

    2014-02-01

    The goal of this study was to investigate the response of activation of Rhizobium tibeticum with mixture of hesperetin and apigenin to improve growth, nodulation, and nitrogen fixation of fenugreek grown under cobalt (Co) stress. The current study showed that high concentrations of Co-induced noxious effects on rhizobial growth, nod gene expression, nodulation, phenylalanine ammonia-lyase (PAL) and glutamine synthetase (GS) activities, total flavonoid content, and nitrogen fixation. Addition of a mixture of hesperetin and apigenin to growth medium supplemented with different concentrations of Co significantly increased bacterial growth. PAL activity of roots grown hydroponically at 100 mg kg(-1) Co and inoculated with induced R. tibeticum was significantly increased compared with plants receiving uninduced R. tibeticum. Total flavonoid content of root exudates of plants inoculated with activated R. tibeticum was significantly increased compared with inoculated plants with unactivated R. tibeticum or uninoculated plants at variant Co dosages. Application of 50 mg kg(-1) Co significantly increased nodulation, GS, nitrogenase activity, and biomass of plants inoculated with either or uninduced R. tibeticum. The total number and fresh mass of nodules, nitrogenase activity, and biomass of plants inoculated with induced cells grown in soil treated with 100 and 200 mg kg(-1) Co were significantly increased compared with plants inoculated with uninduced cells. Induced R. tibeticum with flavonoids significantly alleviates the adverse effect of Co on nod gene expression and therefore enhances nitrogen fixation. Induction of R. tibeticum with compatible flavonoids could be of practical importance in augmenting growth and nitrogen fixation of fenugreek grown in a Co-contaminated agroecosystem. PMID:24366585

  3. Site-directed mutagenesis and DNA sequence of pckA of Rhizobium NGR234, encoding phosphoenolpyruvate carboxykinase: gluconeogenesis and host-dependent symbiotic phenotype.

    Science.gov (United States)

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

    1991-11-01

    We have cloned and sequenced the pckA gene of Rhizobium sp. NGR234, a broad host-range strain. The gene encodes phosphoenolpyruvate carboxykinase (PEPCK), a key enzyme of gluconeogenesis. The locus was isolated and subcloned from a genomic library of NGR234 employing hybridization with an R. meliloti pck gene probe and complementation of a Tn5 mutant in this species. The DNA sequence of pckA (NGR234) was determined and encoded a PEPCK protein of 535 amino acids with a molecular weight of 58.4 kDa. The deduced polypeptide sequence was compared to those of three known ATP-dependent PEPCKs. Slightly higher homology was observed with yeast and trypanosome polypeptides than with that of Escherichia coli. We have identified several regions that are conserved in all four PEPCK proteins. A mutant constructed in the pck gene by site-directed mutagenesis with interposon omega failed to grow on succinate, malate and arabinose but grew on glucose and glycerol as sole carbon sources. These data show that NGR234 requires PEPCK-driven gluconeogenesis to grow on TCA cycle intermediates. A host-dependent effect of the pckA mutation was observed on nodule development and nitrogen fixation. Nodules formed by the site-directed mutant on Leucaena leucocephala and Macroptilium atropurpureum were FixRed, but on Vigna unguiculata were Fix-. The expression of the gene was positively regulated in free-living cells of NGR234 by either succinate or host-plant exudates, and was subject to catabolite repression by glucose. PMID:1720862

  4. Caracterización de cepas de Rhizobium y Bradyrhizobium (con habilidad de nodulación) seleccionados de los cultivos de fríjol caupi (Vigna unguiculata) como potenciales bioinóculos / Characterization of Rhizobium and Bradyrhizobiu´s strains (with ability of nodulation) selected from bean (Vigna unguiculata) cultures as a potentials bioinoculants

    Scientific Electronic Library Online (English)

    Bernarda, Cuadrado; Guillermo, Rubio; Winston, Santos.

    2009-01-01

    Full Text Available Los suelos de Latinoamérica son ácidos y deficientes en nitrógeno; por esta razón es necesario explorar nuevas alternativas con el fin de modular el desarrollo de plantas, especialmente las leguminosas. El uso del potencial de las bacterias para inducir nodulación y fijar el nitrógeno en las plantas [...] leguminosas se ha estudiado como una opción con potencial impacto. En este estudio se analizó la diversidad de cepas de rhizobios aislados del fríjol Vigna unguiculata (fríjol caupí) cultivado en el norte del departamento de Bolívar (Colombia). Se identificaron aislados capaces de crecer mejor en ambientes hostiles (los cuales tienen un uso potencial como bioinoculantes). Se describe además un acercamiento a la taxonomía de estas bioespecies. Se caracterizaron 52 cepas de rizobios (basados en sus características morfológicas, requerimientos de cultivo, metabólicas, resistencia a metales y antibióticos y de autenticación). De acuerdo con sus propiedades de crecimiento, el 63,5% fueron de cepas de lento, mientras que el 36,5%, de rápido crecimiento. Prevalecieron las de lento crecimiento con un 63,5% del total sobre un 36,5% de rápido crecimiento. Los aislados fueron caracterizados de acuerdo con sus patrones de asimilación de carbohidratos, y se encontraron microorganismos de los géneros Rhizobium, Bradyrhizobium y Mesorhizobium (12 cepas identificadas como potenciales bioinoculantes). Abstract in english Latin America´s soils are acidic and nitrogen-deficient, for this reason is necessary to explore new alternatives in order to modulate in the development of plants, specially the leguminous plants. The use of bacteria´s potential to induce nodulation and to fix nitrogen in leguminous plants has been [...] studied as an option with potential impact. In our study, we analyzed the diversity of rhizobial isolated of the bean Vigna unguiculata (beans cowpea) cultured in the north of Bolivar department (Colombia). We identified strains able of growing in hostile environment (which have a potential use like bioinoculants). Additionally, we described an approach to taxonomy of these biospecies. We reached the characterization of 52 rhizobial strains (based on their morphologic, requires of culture, metabolic, resistance to metals and antibiotics and authentication characteristics). According with their growing properties, 63.5 % were slow growth strains while the 36.5 % were of rapid growth. The isolates were characterized according to their assimilation carbohydrate´s pattern, finding microorganism as Rhizobium, Bradyrhizobium and Mesorhizobium (12 of which were identified as potential bioinoculants).

  5. Éducation et Libération

    CERN Document Server

    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...

  6. Et indgreb er klogt

    DEFF Research Database (Denmark)

    Klausen, Kurt Klaudi

    2013-01-01

    Kronikken analyserer lærerkonflikten og argumentrerer for et regeringsindgreb der skaber tidsvarende arbejdstidsforhold i folkeskolen på baggrund af en argumentation om at DLF fastholder lærerne i en vildfarelse vedr. relationen mellem ledere og medarbejdere som tilhører industrisamfundet - ikke videnssamfundet.

  7. 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.

  8. Éducation et Libération

    CERN Document Server

    Education et Libération

    2013-01-01

    Vente d’artisanat du Tiers Monde Mardi 29 et mercredi 30 octobre 2013 CERN, Bâtiment principal Togo, Ecole Arc en ciel, construction des salles de classe. Appel pour le financement de ce chantier afin de libérer l’école de la charge des loyers payés pendant des années. 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 q...

  9. Education et Libération

    CERN Multimedia

    Jean-Pierre Lagnaux

    2013-01-01

    Vente d’artisanat du Tiers Monde Jeudi 23 et vendredi 24 mai 2013 CERN, Bâtiment principal Togo, Ecole Arc en ciel, construction des salles de classe. Appel pour le financement de ce chantier afin de libérer l’école de la charge des loyers payés pendant des années. 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 no...

  10. Éducation et libération

    CERN Multimedia

    Jean-Pierre Lagnaux

    2010-01-01

    26 – 27 avril 2010, de 10 h 00 à 16 h 30 Bâtiment principal Vente d’objet du Tièrs-Monde présentés par EDUCATION et LIBERATION L’Afrique, essentiellement nos engagements au Bénin et au Togo, constitue aujourd’hui notre souci principal. 1. Au Bénin, nous avons pu poursuivre sur notre lancée et soutenons activement la mise en valeur du terrain où notre partenaire fait pousser du manioc, du maïs et des ananas bio. La crise économique qui a frappé le monde depuis 2008, a touché l’Afrique plus durement que l’Europe ou les Etats-Unis d’Amérique mais on a pris l’habitude de penser que c’est normal : on y meurt de toute façon beaucoup plus vite. En particulier : on y meurt beaucoup de faim....

  11. 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.

  12. Paludisme et développement économique

    OpenAIRE

    Thuilliez, Josselin

    2009-01-01

    Cette thèse contribue à la littérature sur la relation endogène entre l'état de santé d'une population et le développement économique d'une nation. Nous nous focalisons pour cela sur un phénomène de grande ampleur touchant de nombreux pays en développement: l'endémie palustre. Dans un premier temps, nous reformulons le cadre théorique dans lequel la relation bidirectionnelle entre paludisme et développement économique est généralement analysée. Nous utilisons un modèle d'épidémiologie économi...

  13. 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...

  14. Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Webb, Robert C. [Texas A& M University; Kamon, Teruki [Texas A& M University; Toback, David [Texas A& M University; Safonov, Alexei [Texas A& M University; Dutta, Bhaskar [Texas A& M University; Dimitri, Nanopoulos [Texas A& M University; Pope, Christopher [Texas A& M University; White, James [Texas A& M University

    2013-11-18

    Overview The High Energy Physics Group at Texas A&M University is submitting this final report for our grant number DE-FG02-95ER40917. This grant has supported our wide range of research activities for over a decade. The reports contained here summarize the latest work done by our research team. Task A (Collider Physics Program): CMS & CDF Profs. T. Kamon, A. Safonov, and D. Toback co-lead the Texas A&M (TAMU) collider program focusing on CDF and CMS experiments. Task D: Particle Physics Theory Our particle physics theory task is the combined effort of Profs. B. Dutta, D. Nanopoulos, and C. Pope. Task E (Underground Physics): LUX & NEXT Profs. R. Webb and J. White(deceased) lead the Xenon-based underground research program consisting of two main thrusts: the first, participation in the LUX two-phase xenon dark matter search experiment and the second, detector R&D primarily aimed at developing future detectors for underground physics (e.g. NEXT and LZ).

  15. A Role for Autoinhibition in Preventing Dimerization of the Transcription Factor ETS1.

    Science.gov (United States)

    Samorodnitsky, Daniel; Szyjka, Courtney; Koudelka, Gerald B

    2015-09-01

    ETS1 is the archetype of the ETS transcription factor (TF) family. ETS TFs share a DNA-binding domain, the ETS domain. All ETS TFs recognize a core GGA(A/T) binding site, and thus ETS TFs are found to redundantly regulate the same genes. However, each ETS TF has unique targets as well. One prevailing hypotheses explaining this duality is that protein-protein interactions, including homodimerization, allow each ETS TF to display distinct behavior. The behavior of ETS1 is further regulated by autoinhibition. Autoinhibition apparently modulates ETS1 DNA binding affinity, but the mechanism of this inhibition is not completely understood. We sought to characterize the relationship between DNA binding and ETS1 homodimer formation. We find that ETS1 interrogates DNA and forms dimers even when the DNA does not contain an ETS recognition sequence. Mutational studies also link nonspecific DNA backbone contacts with dimer formation, in addition to providing a new role for the recognition helix of ETS1 in maintaining the autoinhibited state. Finally, in showing that residues in the DNA recognition helix affect autoinhibition, we define a new function of ETS1 autoinhibition: maintenance of a monomeric state in the absence of DNA. The conservation of relevant amino acid residues across all ETS TFs indicates that the mechanisms of nonspecific DNA interrogation and protein oligomer formation elucidated here may be common to all ETS proteins that autoinhibit. PMID:26195629

  16. Tassements référentiels sur la décharge réhabilitée d’Agadir et suivi des biogaz

    OpenAIRE

    Ahmed Elkadi; Mostapha Maatouk; Mohammed Raissouni; Tahiri Zakariyae Djebary; Abderrahim Mouhssine

    2014-01-01

    La recirculation et réinjection des lixiviats dans le corps des anciens déchets, après leurs couverture finale, est mise en œuvre à titre d’essai sur une partie de la décharge réhabilité pour accélérer la biodégradation de la matière organique, augmenter la production des biogaz et par conséquent favoriser d’avantage la stabilité du massif des déchets. Afin d’assurer une valorisation et une exploitation rationnelle, au niveau environnemental et économique, les biogaz produits sur la première ...

  17. Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Wessels, B. W.

    2002-08-02

    Final report for program on the study of structure and properties of epitaxial oxide films. The defect structure of epitaxial oxide thin films was investigated. Both binary and complex oxides were studied. Epitaxial oxides were synthesized by organometallic chemical vapor deposition (OMCVD). This technique has been found to be highly versatile for the synthesis of a wide range of epitaxial oxide including dielectrics, ferroelectrics and high T{sub c} superconductors. Systems investigated include the binary oxides ZnO and TiO{sub 2} and ferroelectric oxides BaTiO{sub 3}, BaSrTiO{sub 3} and KNbO{sub 3}. Techniques used to evaluate the defect structure included deep level transient spectroscopy (DLTS), photocapacitance spectroscopy, and photoluminescence (PL) spectroscopy. High purity, stoichiometric oxide films were deposited and their defect structure evaluated. Epitaxial ZnO was deposited at temperatures as low as 250 C. PL indicated only near band edge ultraviolet emission showing that both extrinsic and intrinsic point defects could be significantly lowered in OMCVD derived thin films compared to that of the bulk. This presumably was a result of low deposition temperatures and high purity starting materials. Ferroelectric oxides epitaxial thin films of BaTiO{sub 3} and the solid solution BaSrTiO{sub 3} were synthesized and the defect structure determined. Photocapacitance spectroscopy was developed to quantify electrically active defects in the oxides. Defects with concentrations as low as 10{sup 14} cm{sup -3} were observed and their properties determined. A new model was developed for the electronic transport properties of intrinsic and extrinsic BaTiO{sub 3}. A transport model was proposed whereby conduction in La doped films occurs via hopping in localized states within a pseudogap formed between a lower Hubbard band and the conduction band edge. The influence of the size effect on the ferroelectric phase transition in the thin films was investigated. The Curie temperature shifted more than 100 C as a result of strain stabilization of the low symmetry phase. The dielectric properties of BaTiO{sub 3} showed a strong thickness dependence for films ranging from 15 to 320 nm. The dynamic dielectric and non-linear optical relaxation response of the ferroelectric thin films was studied over nine orders of magnitude in time from 1 nsec to 1 sec. A power law dependence of the relaxation response on time was observed and a model developed. The dynamic response was analyzed in terms of relaxation of ferroelectric domains with a continuous size distribution. Domain size ranged from nanometers to microns. This continuous size distribution also leads to a diffuse phase transition as observed for the thin films.

  18. 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.

  19. 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

  20. « Aliments fonctionnels et lipides »

    Directory of Open Access Journals (Sweden)

    Rossignol-Castera Anne

    2001-07-01

    Full Text Available Proposer un dossier sur les aliments fonctionnels dits « aliments-santé » se justifie doublement, d’une part, parce que l’année 2001 est sans conteste marquée par le développement confirmé de ces produits et, d’autre part, parce que les matières grasses (huiles combinées, margarines, etc. et les molécules lipidiques (acides gras poly-insaturés - AGPI - oméga 3, phytostérols, etc. sont fortement concernées par ce secteur. Un aliment fonctionnel peut se définir comme un produit d’alimentarité prouvée, qui présente une composition spécifique ou qui contient un ou des ingrédients affectant de manière ciblée, selon la nature et la dose du ou des nutriments ou ingrédients, une ou plusieurs fonctions de l’organisme dans le but d’obtenir des effets positifs qui puissent justifier une ou des allégations fonctionnelles, voire une ou des allégations de santé. Tous les aliments ayant au minimum une fonction « santé » qui est l’apport énergétique, ces nouveaux aliments doivent donc se démarquer en apportant un bénéfice santé supérieur à l’alimentation classique. Serge Hercberg1 les caractérise par une « valeur santé ajoutée », qui peut être soit une fonction cible améliorée, soit la réduction du risque d’une pathologie. Ainsi, un produit apportant des phytostérols à une dose active pourra contribuer à « diminuer significativement le LDL-cholestérol » et un produit enrichi en AGPI oméga 3 peut revendiquer un apport en nutriments qui « contribuent à la réduction des risques cardiovasculaires ». Il nous paraît important de limiter la notion d’aliment fonctionnel à un produit industriel élaboré pour lequel soit la technologie, soit la formulation, soit les deux ont été volontairement adaptées ou optimisées pour obtenir une fonctionnalité ciblée sur notre métabolisme. On constate en effet un amalgame et une vulgarisation du message « santé » pour des produits qui sont, certes, « bons pour la santé », les fruits et légumes par exemple pour lesquels des études scientifiques ont montré qu’une consommation élevée contribue à la réduction du risque de maladies cardiovasculaires et de certains cancers, mais pour autant on ne peut pas les considérer comme des aliments fonctionnels ! Contrairement aux produits allégés ou diététiques qui répondent à une attente de prévention du capital forme - « Je maîtrise mon corps avec mon alimentation » -, les aliments fonctionnels répondent à un besoin de santé active - « Je mange pour me soigner ». C’est dans ce contexte de bénéfice santé, le plus immédiat possible, que le consommateur peut accepter le prix de ces produits. Les aliments fonctionnels sont porteurs d’une image de haute technicité et perçus comme l’aboutissement d’une recherche pointue, associant le monde industriel au monde de la science, en l’occurrence celle des médecins et des nutritionnistes. Hors de ce contexte, ce type d’aliment n’est pas crédible et est voué à l’échec commercial. La plupart des supports de communication de ces produits - publicité, emballage, site Internet, brochure informative - comportent une référence à des publications scientifiques et surtout à une équipe de recherche, voire un nom, généralement un médecin, qui devient à la fois caution et porte-parole du produit.

  1. Activités estivales et automnales

    CERN Multimedia

    Staff Association

    2013-01-01

    Recharger les batteries et bien plus encore…. Les vacances d’été sont l’occasion idéale de passer plus de temps avec sa famille, de découvrir de nouveaux pays, se faire de nouveaux amis, autrement dit de passer du temps loin de la routine quotidienne. Cette recharge de batteries est essentielle à notre équilibre travail-vie privée, et le CERN, employeur moderne et socialement responsable, en a fait un élément central de sa politique de ressources humaines. Néanmoins, n’oublions pas que même si beaucoup d’entre vous profitent d’une pause estivale bien méritée, certains de nos collègues travaillent dur pour faire du LS1 (premier long arrêt du LHC) un succès afin de garantir que le LHC pourra, dès 2015, commencer à produire des données de physiq...

  2. 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.

  3. Crise, métropolisation, et aménagement

    Directory of Open Access Journals (Sweden)

    Jean-Albert Guieysse

    2014-12-01

    Full Text Available Ce texte développe une conférence tenue à Notre-Dame-des-Landes, lors du rassemblement, le 4 août 2013, des opposants au projet d’un aéroport international pour la métropole de Nantes. La métropolisation, telle que présentée à l’opinion publique, est l’avenir urbain de l’humanité. Nous montrons ici qu’elle est d’abord le résultat de la Crise longue ouverte dans les années 1970, dans laquelle le capitalisme survit en s’adonnant à ses penchants pour la rente, l’économie prédatrice, et la « solution spatiale » de la Mondialisation. Les métropoles sont les points d’ancrage spatial de cette « nouvelle économie ». La métropolisation, dans laquelle, comme toutes les études géographiques le montrent, les déséquilibres et les inégalités s’accroissent, est le faux-semblant urbain d’une réalité d’inversion spatiale et de désurbanisation, soumise aux flux centrifuges créés par la Crise.

  4. Mémoire et identité: la géographie au baccalauréat, et auparavant

    Directory of Open Access Journals (Sweden)

    Roger Brunet

    1999-12-01

    Full Text Available Les nouvelles épreuves de géographie du baccalauréat et la distinction entre carte, schéma et croquis sont cohérentes avec la logique même de l'apprentissage de la géographie et de l'analyse géographique. Mettant en valeur la mémoire et l'identité des lieux et des territoires, elles supposent de placer au centre du travail le «schéma», c'est-à-dire l'identification des formes par référence à des modèles.

  5. 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.

  6. 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.

  7. 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

  8. 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.

  9. Burlesque et interprétation

    Directory of Open Access Journals (Sweden)

    Claudine Nédélec

    2007-11-01

    Full Text Available Je voudrais mettre cette communication sous une triple égide (on n’est jamais trop bien protégé :celle de Rabelais,Et posé le cas qu’au sens literal vous trouvez matieres assez joyeuses et bien corrrespondentes au nom, toutesfois pas demourer là ne fault, comme au chant des Sirenes, ains à plus hault sens interpreter ce que par adventure cuidiez dict en gayeté de cueur. (Gargantua, prologuecelle de Montaigne,Il y a plus affaire à interpreter les interpretations qu’à interpreter les choses, ...

  10. 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

  11. Conflits et conflictualités

    Directory of Open Access Journals (Sweden)

    2010-12-01

    Full Text Available Conflits de proximitéLe premier panel du séminaire s’est articulé autour du conflit de proximité. Ouvert par une introduction consacrée aux liens entre voisinage et violence, il a apporté deux illustrations à travers deux études de cas : à l’échelle d’une institution culturelle franco-allemande d’abord, puis au sein d’une communauté sociale particulière.La communication de Ulrich Bielefeld, intitulée « Proximité et violence », envisage le voisinage comme champ d’émergence du conflit, au sens ...

  12. Globalisation et espaces locaux

    Directory of Open Access Journals (Sweden)

    Évelyne Mesclier

    2011-04-01

    Full Text Available Cet ouvrage, épais volume de plus de 600?pages, explore les liens entre la globalisation et les espaces locaux. La plupart des vingt et quelque contributions portent sur le Mexique, le plus souvent sur l’État de Guanajuato, mais quelques-unes présentent des études de cas réalisées au Brésil, en Argentine ou à Porto Rico, voire en Inde ou au Mali. Dans l’ensemble, disons-le d’emblée, ce choix emporte l’adhésion?: la confrontation d’observations centrées sur un terrain particulier à des éclaira...

  13. Intégrations et dépendances

    Directory of Open Access Journals (Sweden)

    Didier Benjamin

    1999-06-01

    Full Text Available L'analyse des échanges commerciaux et des transferts publics dans les outre-mers indique une nette polarisation des flux vers la France et les pays de l'OCDE, au détriment des relations avec leur proche environnement géographique. Le constat de cette dépendance économique ne peut ignorer la nécessité d'un rattrapage des niveaux socioéconomiques ultramarins, dans la perspective d'une intégration des outre-mers dans l'espace national. Il s'agit désormais de trouver des réponses adaptées aux défis de l'intégration européenne.

  14. Avalanches : phénomènes et enjeux.

    OpenAIRE

    Ancey, Christophe

    2009-01-01

    Si les avalanches ne constituent pas un danger naturel majeur à l'échelle de la planète, elles représentent une menace et une contrainte fortes pour un pays montagneux comme la Suisse. Ce n'est donc pas un hasard si la Suisse a été la pionnière dans l'étude scientifique des avalanches avec les travaux d'un ingénieur forestier des Grisons, Johann Coaz, à la fin du XIXe siècle. Et c'est également sur le modèle suisse de zonage des risques - établi après le terrible hiver 1951 (98 morts) - que t...

  15. Porvoo - et højkirkeligt projekt

    DEFF Research Database (Denmark)

    Balslev-Clausen, Peter

    2010-01-01

    9. december 2009 underskrev Det mellemkirkelige Råd på Den danske Folkekirkes vegne den anglikansk-lutherske Porvoo-erklæring. Artiklen påviser, at Porvoo-samarbejdet bygger på et kirke- og embedssyn, de er fremmed for Den danske  Folkekirkes demokratisk-lutherske tradition. Som et illustrerende eksempel på forskellem mellem evangelisk-luthersk og anglikansk kristendomsforståelse anføres anglikaneren S. Baring-Gould's oversættelse af lutheraneren B.S. Ingemanns salme "Igennem nat og trængsel". Artiklen konkluderer, at Porvoo-tilslutningen over tid vil kunne få gennemgribende teologisk og forfatningsmæssig betydning for Den danske Folkekirke. Udgivelsesdato: September 2010

  16. Technologie et spécialisation internationale touristique

    OpenAIRE

    Sihabutr, Chaturaporn

    2012-01-01

    Cette recherche a pour objet d'examiner l'importance des facteurs technologiques dans la spécialisation internationale touristique. Le test consiste, à partir des données liées au tourisme et à la technologie, à synthétiser la corrélation existante entre tourisme et facteurs technologiques dans les dépenses du tourisme domestique et international, l'investissement touristique et les dépenses en recherche et développement (R&D), à partir d'une analyse comparative de données de 2000 à 2010, en ...

  17. Senhjerneskade i et forståelsesperspektiv

    DEFF Research Database (Denmark)

    Nielsen, Charlotte Marie Bisgaard

    2015-01-01

    Artiklen anskueliggør, gennem et signifikant nedslag i materialet fra et moderne praksisstudie på et senhjerneskadecenter, hvorvidt personer med senhjerneskade stadig defineres som personer, når de optræder i hverdagskommunikationer, hvor der også optræder hukommelsessvigt og pleje. Altså, hvad sker der, når personer med senhjerneskade i praksis møder sundhedsprofessionelles normer, krav og ønsker om at behandle eller udbedre skaden? Det engelske låneord for ‘selvhjulpet’; ’how-abled’ (Raudaskoski, 2013) versus ‘handicappet’/hhv. ’disabled’ beskriver bedst artiklens forudsatte forståelse af senhjerneskade, forståelsesressourcer og inklusions- og eksklusionspraksisser. Artiklen redegør inden for denne forståelsesramme for interaktionsperspektiver og operationaliserer et sprogpsykologisk forståelsesperspektiv. Det konkluderes, at teoretikere, praktikere og analytikere inden for sundhedskommunikation kan drage nytte af det praksisfokus, interaktionsanalytiske værktøjer kan give. Artiklen giver forslag til ændring af praksis vha. ‘let pass-strategien’ (Wilkinson, 2011, s. 44). Målgruppen er sundhedspersonale samt fagfæller, undervisere og studerende inden for sundhedskommunikation og sprog- og kommunikationsuddannelser på længere videregående uddannelser. Desuden er artiklen interessant for senhjerneskadede og pårørende. Raudaskoski, P. (2013). From understanding to participation: A relational approach to embodied practices. I: Keisanen, T., Kärkkäinen, E., Rauniomaa, M., Siitonen, P. & Siromaa, M. (red.), Multimodal discourses of participation. AfinLA Yearbook, Vol, 71, 103-121. Wilkinson, R. (2011). Changing interactional behavior: Using Conversation Analysis in intervention programmes for aphasic conversation. I: Antaki, C. (red.), Applied Conversation Analysis – intervention and change in institutional talk. (32-53). Basingstoke. Palgrave Macmillan.

  18. Socialrådgivere i et krydspres

    DEFF Research Database (Denmark)

    MØller, Marie Østergaard

    2011-01-01

    Kapitlet sætter fokus på de arbejdsbetingelser, der kendetegner offentlige ansatte set fra et nærbureaukratisk perspektiv, som er der hvor borgerne møder staten. Det er disse offentligt ansatte, de såkaldte markarbejdere, der håndterer en magtfuld og ofte ambivalent transformationsproces af demokratisk vedtagne beslutninger til konkrete juridiske og økonomiske afgørelser, der kan have stor betydning for borgerens identitet og sociale status. Det er også dem, der er med til at skabe borgernes billede af staten, når de har talt med, modtaget hjælp fra, eller er blevet sanktioneret af en offentlig myndighed. Kapitlet har et dobbelt ærinde. Først præsenteres markarbejderbegrebet som et begreb til at forstå det krydspres markarbejdere oplever, når de i lovens navn må skønne hvilket behov og hvilke rettigheder hjælpesøgende borgere har, dernæst fokuserer kapitlet eksplicit på socialrådgivere som en markarbejdergruppe. Til sidst introducerer kapitlet et begreb om borgernes erfaringsdannelse om staten, samfundet og de demokratiske spilleregler, der handler om den opfattelse borgerne får af staten efter de har interageret med en markarbejder i nærbureaukratiet.

  19. Patpong, entre sexe et commerce.

    Directory of Open Access Journals (Sweden)

    Sébastien Roux

    2010-03-01

    Full Text Available Le tourisme dit « sexuel » est aujourd’hui décrié comme une forme de tourisme international immoral, un dysfonctionnement grave de la mondialisation appelant une réaction politique contre « l’exploitation sexuelle » dont seraient victimes des millions de femmes et d’enfants. Pourtant, derrière l’apparente évidence du « tourisme sexuel » comme expression de sens commun, rares sont les enquêtes qui explicitent la réalité concrète des échanges prostitutionnels. En adoptant une démarche ethnographique, l’article décrit le fonctionnement de Patpong, un quartier rouge de Bangkok dédié à une clientèle internationale. Par la description des offres disponibles, des revenus générés, des codes et des pratiques, la complexité de l’espace réapparaît. Il s’agit de donner à voir la réalité des échanges pour interroger l’articulation entre commerce et sexualité. L’analyse ethnographique du tourisme sexuel permet ainsi de souligner la diversité des pratiques et de rappeler que les formes les plus visibles — et les plus commentées — d’échanges prostitutionnels éclipsent trop souvent une pluralité d’expériences qui participe pourtant au succès de ces ruelles mondialement connues. So-called sex tourism is condemned as an immoral form of international tourism, a serious failure of globalization requiring political action against the “sexual exploitation” suffered by millions of women and children. Yet behind the common and seemingly evident understanding of “sexual tourism,” few studies have focused on the actual reality of such relations. Based on an ethnographic study, this article presents the structure of Patpong, a red-light district of Bangkok dedicated to international tourism. First, the article aims to briefly present the historical development of Patpong. This peculiar space is intrinsically linked to sex tourism, as these world-renowned streets expanded since the mid-60s to become one of the most famous red-light districts in Southeast Asia. Initially linked to the gi s’ military presence in Thailand during the Vietnam War, “recreational bars” have grown during the boom of international tourism. Limited to some specific areas, these bars became world-famous and started to be harshly discussed. Then the article describes how Patpong is organized. In actuality this area is not only dedicated to commercial sex but also to business. By underlining the presence of a Night Bazaar, and also drug shops, restaurants, discos, even jewelries, the depiction of Patpong reminds us of the complexity of exchanges that defines this red-light district. If commercial sex seems omnipresent, it has to be understood as a specific form of business developed in order to rationally maximize the benefits of the international visitors’ presence. Finally, the diversity of sexual offers is detailed. By describing the many available services, the incomes generated, the codes of conduct, and practices, the complexity of Patpong surfaces. The article not only depicts the diversity of sexual establishments and their rules (i.e., go-go bars, beer bars, sex shows, etc., but also points out the influence of non-sexual establishments, such as “regular” bars and the like. In fact, some prostitution activities take the form of ordinary relations and make us rethink the fine balance between sexuality and business. The ethnographical analysis of sex tourism thus highlights the multiplicity of practices and reminds us that the most visible — and most notorious — forms of prostitution often dismiss the multiple and complex factors that nonetheless contribute to the success of international sex.

  20. Le vieillard et le chevalier

    Directory of Open Access Journals (Sweden)

    Mélanie JECKER

    2010-05-01

    Full Text Available La fin du Moyen Âge fascine. Deux facteurs principaux expliquent l’attraction qu’exerce cette période : elle apparaît d’une part comme un moment historique riche car double, phase de transition entre le Moyen Âge et la Renaissance, où se mêlent des cadres de représentation anciens et nouveaux. L’insinuation d’une pensée humaniste balbutiante s’y traduirait notamment par l’émergence de la notion d’individu, qui constitue l’un des objets de ce travail. Il faut invoquer, d’autre part, l’image macabre d’un bas Moyen Âge hanté par l’idée de la maladie et de la mort depuis l’épidémie de peste noire de 1348, obsédé par la brièveté de la vie humaine. Ces deux facettes de « l’automne du Moyen Âge » tel que l’évoque avec poésie Joan Huizinga sont-elles autre chose qu’une plaisante image d’Epinal? Cette étude cherche précisément à déterminer le degré de validité de ces deux topiques, à travers l’analyse de la représentation des âges de la vie dans un corpus bien défini, celui de la biographie chevaleresque castillane du XVe siècle. L’intérêt porté à l’individu, la conscience de la singularité impliquent en effet celle du caractère mouvant de la personne, or quel thème mieux que celui des âges permet de confirmer ou d’infirmer l’hypothèse du surgissement d’une nouvelle manière de concevoir l’homme, proprement « renaissante », en ce siècle de transition , La nature même du corpus retenu – des récits biographiques – suggère en effet une mutation dans l’appréhension de la personne, une attention prêtée à sa progressive transformation. L’étude de la représentation de la vieillesse, en particulier, révèle non seulement à quel point était alors réelle cette prétendue obsession de la déchéance physique et de la mortalité, mais aussi dans quelle mesure étaient soulignés et valorisés les changements individuels parallèles à l’avancée en âge.El final de la Edad Media fascina. Dos factores principales aclaran la atracción que ejerce este período : aparece, por una parte, como un momento histórico rico porque doble, fase de transición entre la Edad Media y el Renacimiento, en la cual se mezclan marcos de representación antiguos y nuevos. La introducción de un pensamiento humanista balbuceante se manifestaría especialmente por el surgir de la noción de individuo, la cual constituye uno de los objetos de este trabajo. Conviene invocar, por otra parte, la imagen macabra de una baja Edad Media atormentada, desde la epidemia de peste negra de 1348, por la idea de enfermedad y de muerte, obsesionada por la brevedad de la vida humana. Ahora bien, podría ser que estas dos facetas del « otoño de la Edad Media » tal como lo evoca poéticamente Joan Huizinga no fueran sino amenos tópicos. Este estudio pretende precisamente determinar el grado de validez de ambos a través del análisis de la representación de las edades del hombre en un género bien definido, el de la biografía caballeresca castellana del siglo XV. El interés por el individuo, la conciencia de la singularidad implican en efecto la del carácter móvil de la persona, ahora bien ¿ qué tema mejor que el de las edades permite confirmar o rebatir la hipótesis de la aparición de una nueva manera de concebir al hombre, propiamente « renaciente », en este siglo de transición , La índole misma del conjunto de textos seleccionado – relatos biográficos – sugiere en efecto una mutación en la comprensión de la persona, una atención prestada a su progresiva transformación. El estudio de la representación de la vejez, en particular, desvela no sólo hasta qué punto era entonces real la supuesta obsesión por el decaimiento físico y la mortalidad, sino también en qué medida se valoraban los cambios individuales paralelos al envejecimiento.