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Sample records for rhizobium etli cfn42

  1. Transcriptomic analysis of the process of biofilm formation in Rhizobium etli CFN42.

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    Reyes-Pérez, Agustín; Vargas, María Del Carmen; Hernández, Magdalena; Aguirre-von-Wobeser, Eneas; Pérez-Rueda, Ernesto; Encarnacion, Sergio

    2016-11-01

    Organisms belonging to the genus Rhizobium colonize leguminous plant roots and establish a mutually beneficial symbiosis. Biofilms are structured ecosystems in which microbes are embedded in a matrix of extracellular polymeric substances, and their development is a multistep process. The biofilm formation processes of R. etli CFN42 were analyzed at an early (24-h incubation) and mature stage (72 h), comparing cells in the biofilm with cells remaining in the planktonic stage. A genome-wide microarray analysis identified 498 differentially regulated genes, implying that expression of ~8.3 % of the total R. etli gene content was altered during biofilm formation. In biofilms-attached cells, genes encoding proteins with diverse functions were overexpressed including genes involved in membrane synthesis, transport and chemotaxis, repression of flagellin synthesis, as well as surface components (particularly exopolysaccharides and lipopolysaccharides), in combination with the presence of activators or stimulators of N-acyl-homoserine lactone synthesis This suggests that R. etli is able to sense surrounding environmental conditions and accordingly regulate the transition from planktonic and biofilm growth. In contrast, planktonic cells differentially expressed genes associated with transport, motility (flagellar and twitching) and inhibition of exopolysaccharide synthesis. To our knowledge, this is the first report of nodulation and nitrogen assimilation-related genes being involved in biofilm formation in R. etli. These results contribute to the understanding of the physiological changes involved in biofilm formation by bacteria.

  2. 菜豆根瘤菌Rhizobium etli CFN42全基因组含信号肽分泌蛋白的鉴定与分析%Genome-wide Identification and Analyses of the Classical Secreted Proteins of Rhizobium etli CFN42

    Institute of Scientific and Technical Information of China (English)

    张武; 马金田; 潘伟; 雷腾英

    2014-01-01

    利用菜豆根瘤菌Rhizobium etli CFN42全基因组测序结果,结合计算机技术和生物信息学分析方法,对菜豆根瘤菌蛋白质组中的分泌蛋白进行预测和分析,以便更深入地了解共生固氮的分子机制.经过分析发现,在该根瘤菌5 963个蛋白质中,具有信号肽的分泌蛋白332个,占总数的5.4%,主要涉及底物转运、物质代谢和信号转导等方面.在有功能描述的186个分泌蛋白中,识别了Ⅰ、Ⅱ、Ⅲ、Ⅳ型分泌系统和丝氨酸蛋白酶,这些蛋白质可能参与了根瘤菌对宿主植物的侵染,是两者分子对话的关键参与者;在假定蛋白中,通过结构域分析,发现了SH3b、BA14K和EFh结构域,含有这些结构域的分泌蛋白可能参与了根瘤信号转导途径.在根瘤菌共生结瘤过程中,分泌蛋白发挥了重要作用.

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

    OpenAIRE

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

    2002-01-01

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

  4. The relaxase of the Rhizobium etli symbiotic plasmid shows nic site cis-acting preference.

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    Pérez-Mendoza, Daniel; Lucas, María; Muñoz, Socorro; Herrera-Cervera, José A; Olivares, José; de la Cruz, Fernando; Sanjuán, Juan

    2006-11-01

    Genetic and biochemical characterization of TraA, the relaxase of symbiotic plasmid pRetCFN42d from Rhizobium etli, is described. After purifying the relaxase domain (N265TraA), we demonstrated nic binding and cleavage activity in vitro and thus characterized for the first time the nick site (nic) of a plasmid in the family Rhizobiaceae. We studied the range of N265TraA relaxase specificity in vitro by testing different oligonucleotides in binding and nicking assays. In addition, the ability of pRetCFN42d to mobilize different Rhizobiaceae plasmid origins of transfer (oriT) was examined. Data obtained with these approaches allowed us to establish functional and phylogenetic relationships between different plasmids of this family. Our results suggest novel characteristics of the R. etli pSym relaxase for previously described conjugative systems, with emphasis on the oriT cis-acting preference of this enzyme and its possible biological relevance.

  5. BacS: an abundant bacteroid protein in Rhizobium etli whose expression ex planta requires nifA.

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    Jahn, Olivia J; Davila, Guillermo; Romero, David; Noel, K Dale

    2003-01-01

    Rhizobium etli CFN42 bacteroids from bean nodules possessed an abundant 16-kDa protein (BacS) that was found in the membrane pellet after cell disruption. This protein was not detected in bacteria cultured in tryptone-yeast extract. In minimal media, it was produced at low oxygen concentration but not in a mutant whose nifA was disrupted. N-terminal sequencing of the protein led to isolation of a bacS DNA fragment. DNA hybridization and nucleotide sequencing revealed three copies of the bacS gene, all residing on the main symbiotic plasmid of strain CFN42. A stretch of 304 nucleotides, exactly conserved upstream of all three bacS open reading frames, had very close matches with the NifA and sigma 54 consensus binding sequences. The only bacS homology in the genetic sequence databases was to three hypothetical proteins of unknown function, all from rhizobial species. Mutation and genetic complementation indicated that each of the bacS genes gives rise to a BacS polypeptide. Mutants disrupted or deleted in all three genes did not produce the BacS polypeptide but were Nod+ and Fix+ on Phaseolus vulgaris.

  6. The symbiovar trifolii of Rhizobium bangladeshense and Rhizobium aegyptiacum sp. nov. nodulate Trifolium alexandrinum in Egypt.

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    Shamseldin, Abdelaal; Carro, Lorena; Peix, Alvaro; Velázquez, Encarna; Moawad, Hassan; Sadowsky, Michael J

    2016-06-01

    In the present work we analyzed the taxonomic status of several Rhizobium strains isolated from Trifolium alexandrinum L. nodules in Egypt. The 16S rRNA genes of these strains were identical to those of Rhizobium bangladeshense BLR175(T) and Rhizobium binae BLR195(T). However, the analyses of recA and atpD genes split the strains into two clusters. Cluster II strains are identified as R. bangladeshense with >98% similarity values in both genes. The cluster I strains are phylogenetically related to Rhizobium etli CFN42(T) and R. bangladeshense BLR175(T), but with less than 94% similarity values in recA and atpD genes. DNA-DNA hybridization analysis showed 42% and 48% average relatedness between the strain 1010(T) from cluster I with respect to R. bangladeshense BLR175(T) and R. etli CFN42(T), respectively. Phenotypic characteristics of cluster I strains also differed from those of their closest related Rhizobium species. Analysis of the nodC gene showed that the strains belong to two groups within the symbiovar trifolii which was identified in Egypt linked to the species R. bangladeshense. Based on the genotypic and phenotypic characteristics, the group I strains belong to a new species for which the name Rhizobium aegyptiacum sp. nov. (sv. trifolii) is proposed, with strain 1010(T) being designated as the type strain (= USDA 7124(T)=LMG 29296(T)=CECT 9098(T)).

  7. 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.

  8. Transcriptional Activation of Virulence Genes of Rhizobium etli.

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    Wang, Luyao; Lacroix, Benoît; Guo, Jianhua; Citovsky, Vitaly

    2017-03-15

    Recently, Rhizobium etli, in addition to Agrobacterium spp., has emerged as a prokaryotic species whose genome encodes a functional machinery for DNA transfer to plant cells. To understand this R. etli-mediated genetic transformation, it would be useful to define how its vir genes respond to the host plants. Here, we explored the transcriptional activation of the vir genes contained on the R. etli p42a plasmid. Using a reporter construct harboring lacZ under the control of the R. etli virE promoter, we show that the signal phenolic molecule acetosyringone (AS) induces R. etli vir gene expression both in an R. etli background and in an Agrobacterium tumefaciens background. Furthermore, in both bacterial backgrounds, the p42a plasmid also promoted plant genetic transformation with a reporter transfer DNA (T-DNA). Importantly, the R. etli vir genes were transcriptionally activated by AS in a bacterial species-specific fashion in regard to the VirA/VirG signal sensor system, and this activation was induced by signals from the natural host species of this bacterium but not from nonhost plants. The early kinetics of transcriptional activation of the major vir genes of R. etli also revealed several features distinct from those known for A. tumefaciens: the expression of the virG gene reached saturation relatively quickly, and virB2, which in R. etli is located outside the virB operon, was expressed only at low levels and did not respond to AS. These differences in vir gene transcription may contribute to the lower efficiency of T-DNA transfer of R. etli p42a than of T-DNA transfer of pTiC58 of A. tumefaciensIMPORTANCE The region encoding homologs of Agrobacterium tumefaciens virulence genes in the Rhizobium etli CE3 p42a plasmid was the first endogenous virulence system encoded by the genome of a non-Agrobacterium species demonstrated to be functional in DNA transfer and stable integration into the plant cell genome. In this study, we explored the transcriptional

  9. The naringenin-induced exoproteome of Rhizobium etli CE3.

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    Meneses, Niurka; Taboada, Hermenegildo; Dunn, Michael F; Vargas, María Del Carmen; Buchs, Natasha; Heller, Manfred; Encarnación, Sergio

    2017-03-02

    Flavonoids excreted by legume roots induce the expression of symbiotically essential nodulation (nod) genes in rhizobia, as well as that of specific protein export systems. In the bean microsymbiont Rhizobium etli CE3, nod genes are induced by the flavonoid naringenin. In this study, we identified 693 proteins in the exoproteome of strain CE3 grown in minimal medium with or without naringenin, with 101 and 100 exoproteins being exclusive to these conditions, respectively. Four hundred ninety-two (71%) of the extracellular proteins were found in both cultures. Of the total exoproteins identified, nearly 35% were also present in the intracellular proteome of R. etli bacteroids, 27% had N-terminal signal sequences and a significant number had previously demonstrated or possible novel roles in symbiosis, including bacterial cell surface modification, adhesins, proteins classified as MAMPs (microbe-associated molecular patterns), such as flagellin and EF-Tu, and several normally cytoplasmic proteins as Ndk and glycolytic enzymes, which are known to have extracellular "moonlighting" roles in bacteria that interact with eukaryotic cells. It is noteworthy that the transmembrane ß (1,2) glucan biosynthesis protein NdvB, an essential symbiotic protein in rhizobia, was found in the R. etli naringenin-induced exoproteome. In addition, potential binding sites for two nod-gene transcriptional regulators (NodD) occurred somewhat more frequently in the promoters of genes encoding naringenin-induced exoproteins in comparison to those ofexoproteins found in the control condition.

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

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    Brom Susana

    2011-06-01

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

  11. NCBI nr-aa BLAST: CBRC-DYAK-06-0020 [SEVENS

    Lifescience Database Archive (English)

    Full Text Available CBRC-DYAK-06-0020 ref|YP_470206.1| hypothetical protein RHE_CH02708 [Rhizobium etli... CFN 42] gb|ABC91479.1| hypothetical protein RHE_CH02708 [Rhizobium etli CFN 42] YP_470206.1 1e-06 26% ...

  12. NCBI nr-aa BLAST: CBRC-BTAU-01-2840 [SEVENS

    Lifescience Database Archive (English)

    Full Text Available CBRC-BTAU-01-2840 ref|YP_470206.1| hypothetical protein RHE_CH02708 [Rhizobium etli... CFN 42] gb|ABC91479.1| hypothetical protein RHE_CH02708 [Rhizobium etli CFN 42] YP_470206.1 6e-11 35% ...

  13. NCBI nr-aa BLAST: CBRC-DSIM-04-0020 [SEVENS

    Lifescience Database Archive (English)

    Full Text Available CBRC-DSIM-04-0020 ref|YP_470206.1| hypothetical protein RHE_CH02708 [Rhizobium etli... CFN 42] gb|ABC91479.1| hypothetical protein RHE_CH02708 [Rhizobium etli CFN 42] YP_470206.1 3e-06 29% ...

  14. NCBI nr-aa BLAST: CBRC-SARA-01-1012 [SEVENS

    Lifescience Database Archive (English)

    Full Text Available CBRC-SARA-01-1012 ref|YP_468056.1| phosphate ABC transporter, permease protein [Rhizobium... etli CFN 42] gb|ABC89329.1| phosphate ABC transporter, permease protein [Rhizobium etli CFN 42] YP_468056.1 1.1 27% ...

  15. NCBI nr-aa BLAST: CBRC-TGUT-11-0009 [SEVENS

    Lifescience Database Archive (English)

    Full Text Available CBRC-TGUT-11-0009 ref|YP_470206.1| hypothetical protein RHE_CH02708 [Rhizobium etli... CFN 42] gb|ABC91479.1| hypothetical protein RHE_CH02708 [Rhizobium etli CFN 42] YP_470206.1 3e-18 33% ...

  16. NCBI nr-aa BLAST: CBRC-DSIM-03-0037 [SEVENS

    Lifescience Database Archive (English)

    Full Text Available CBRC-DSIM-03-0037 ref|YP_470206.1| hypothetical protein RHE_CH02708 [Rhizobium etli... CFN 42] gb|ABC91479.1| hypothetical protein RHE_CH02708 [Rhizobium etli CFN 42] YP_470206.1 4e-07 31% ...

  17. NCBI nr-aa BLAST: CBRC-RNOR-19-0030 [SEVENS

    Lifescience Database Archive (English)

    Full Text Available CBRC-RNOR-19-0030 ref|YP_470206.1| hypothetical protein RHE_CH02708 [Rhizobium etli... CFN 42] gb|ABC91479.1| hypothetical protein RHE_CH02708 [Rhizobium etli CFN 42] YP_470206.1 3e-21 42% ...

  18. NCBI nr-aa BLAST: CBRC-GACU-08-0003 [SEVENS

    Lifescience Database Archive (English)

    Full Text Available CBRC-GACU-08-0003 ref|YP_470206.1| hypothetical protein RHE_CH02708 [Rhizobium etli... CFN 42] gb|ABC91479.1| hypothetical protein RHE_CH02708 [Rhizobium etli CFN 42] YP_470206.1 2e-30 31% ...

  19. NCBI nr-aa BLAST: CBRC-DSIM-04-0099 [SEVENS

    Lifescience Database Archive (English)

    Full Text Available CBRC-DSIM-04-0099 ref|YP_470206.1| hypothetical protein RHE_CH02708 [Rhizobium etli... CFN 42] gb|ABC91479.1| hypothetical protein RHE_CH02708 [Rhizobium etli CFN 42] YP_470206.1 0.084 26% ...

  20. 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...

  1. Natural endophytic association between Rhizobium etli and maize (Zea mays L.).

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    Gutiérrez-Zamora, M L; Martínez-Romero, E

    2001-10-04

    Maize (Zea mays) and bean (Phaseolus vulgaris) have been traditionally grown in association for thousands of years in Mesoamerica. From surface sterilized maize roots, we have isolated over 60 Rhizobium strains that correspond to Rhizobium etli bv. phaseoli (the main symbiont of bean) on the basis of 16S rRNA gene restriction patterns, metabolic enzyme electropherotypes, organization of nif genes, and the ability to nodulate beans. The colonization capacity of some of the isolates was tested with an unimproved maize cultivar and with 30 maize land races. Increases in plant dry weight upon R. etli inoculation were recorded with some of the land races, and these increases may be related to plant growth promotion effects. Additionally, from within maize grown in monoculture we have also recovered R. etli isolates recognizable by their 16S rRNA gene types, which lack nif genes and are incapable of nodulating bean. These strains are presumed to correspond to the earlier described non-symbiotic R. etli obtained from bean rhizosphere.

  2. rosR, a determinant of nodulation competitiveness in Rhizobium etli.

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    Bittinger, M A; Milner, J L; Saville, B J; Handelsman, J

    1997-03-01

    We previously described a Tn5 mutant of Rhizobium etli strain CE3, designated CE3003, that is decreased in nodulation competitiveness, reduced in competitive growth in the rhizosphere, and has a hydrophobic cell surface (R. S. Araujo, E. A. Robleto, and J. Handelsman, Appl. Environ. Microbiol., 60:1430-1436, 1994). To determine the molecular basis for the mutant phenotypes, we identified a 1.2-kb fragment of DNA derived from the parent that restored the wild-type phenotypes to the mutant. DNA sequence analysis indicated that this 1.2-kb fragment contained a single open reading frame that we designated rosR. The Tn5 insertion in CE3003 was within rosR. We constructed a derivative of CE3 that contained a deletion in rosR, and this mutant was phenotypically indistinguishable from CE3003 in cell surface and competitive characteristics. Based on the nucleotide sequence, the deduced RosR amino acid sequence is 80% identical to that of the Ros protein from Agrobacterium tumefaciens and the MucR protein from Rhizobium meliloti. Both Ros and MucR are transcriptional repressors that contain a putative zinc-finger DNA-binding domain. This study defines a gene, rosR, that is homologous to a family of transcriptional regulators and contributes to nodulation competitiveness of R. etli. Moreover, we established that a single gene affects nodulation competitiveness, competitive growth in the rhizosphere, and cell surface hydrophobicity.

  3. 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 (π was greater in DNA segments with recombinant events than in non-recombinant segments. However, this degree of recombination was not sufficiently large to disrupt the congruence of the phylogenetic trees, and further evaluation of recombination in strains quartets indicated that the recombination levels in this species are proportionally low. Conclusion Our data suggest that R. etli is a species composed of separated lineages with low homologous recombination among the strains. Horizontal gene transfer, particularly via the symbiotic plasmid characteristic of this species, seems to play an important role in diversity but the lineages maintain their evolutionary cohesiveness.

  4. Applying reversible mutations of nodulation and nitrogen-fixation genes to study social cheating in Rhizobium etli-legume interaction.

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    Ling, Jun; Zheng, Huiming; Katzianer, David S; Wang, Hui; Zhong, Zengtao; Zhu, Jun

    2013-01-01

    Mutualisms are common in nature, though these symbioses can be quite permeable to cheaters in situations where one individual parasitizes the other by discontinuing cooperation yet still exploits the benefits of the partnership. In the Rhizobium-legume system, there are two separate contexts, namely nodulation and nitrogen fixation processes, by which resident Rhizobium individuals can benefit by cheating. Here, we constructed reversible and irreversible mutations in key nodulation and nitrogen-fixation pathways of Rhizobium etli and compared their interaction with plant hosts Phaseolus vulgaris to that of wild type. We show that R. etli reversible mutants deficient in nodulation factor production are capable of intra-specific cheating, wherein mutants exploit other Rhizobium individuals capable of producing these factors. Similarly, we show that R. etli mutants are also capable of cheating inter-specifically, colonizing the host legume yet contributing nothing to the partnership in terms of nitrogen fixation. Our findings indicate that cheating is possible in both of these frameworks, seemingly without damaging the stability of the mutualism itself. These results may potentially help explain observations suggesting that legume plants are commonly infected by multiple bacterial lineages during the nodulation process.

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

    OpenAIRE

    Mendoza-Hernández Guillermo; Encarnación Sergio; Meneses Niurka

    2010-01-01

    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 extra...

  6. 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.

  7. Determinants of nodulation competitiveness in Rhizobium etli. Final report for period September 30, 1996--September 29, 1999

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    Handelsman, Jo

    2000-01-04

    Nitrogen is a major limiting nutrient in crop production. Chemical fertilizers, which are used extensively to meet crop nitrogen requirements, contribute to the high energy inputs of modern agriculture and cause human health and environmental problems. Legumes and their bacterial associates have long been used in crop rotations to replenish soil nitrogen, but effective and reliable biological nitrogen fixation for beans is prevented by the lack of nodulation competitiveness of many Rhizobium strains used as inoculants. The result is that the inoculant strains will not occupy the host's nodules and no benefit will be derived from inoculation. Many indigenous soil strains of Rhizobium etli bv. phaseoli, the symbiont of bean, nodulate but fix little or no nitrogen, and therefore the nodulation competitiveness problem is significant for achieving maximum nitrogen benefit from bean crops. This project was directed toward developing an understanding of the basis of nodulation competitiveness.

  8. 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.

  9. Interaction entre différentes souches de Rhizobium lupini et les espèces ou cultivars de lupin (Lupinus albus, Lupinus luteus et Lupinus mutabilis)

    OpenAIRE

    LAGACHERIE, Bernard; Bours, Michele; Giraud, J Jacques; SOMMER, Georges

    1983-01-01

    L’efficacité fixatrice de souches de Rhizobium lupini a été mesurée en serre sur Lupinus albus, luteus et mutabilis. De fortes interactions se manifestent : 86 p. 100 des souches testées ont une bonne efficacité sur L. albus, 52 p. 100 sur L. mutabilis et 40 p. 100 sur L. luteus ; 22 p. 100 des souches ont une bonne efficacité fixatrice sur les trois espèces. Les interactions observées en serre se conservent au champ où les souches fixatrices augmentent le rendement en grain et la teneur ...

  10. Genomic analysis of cyclic-di-GMP-related genes in rhizobial type strains and functional analysis in Rhizobium etli.

    Science.gov (United States)

    Gao, Shanjun; Romdhane, Samir Ben; Beullens, Serge; Kaever, Volkhard; Lambrichts, Ivo; Fauvart, Maarten; Michiels, Jan

    2014-05-01

    Rhizobia are soil bacteria that can fix nitrogen in symbiosis with leguminous plants or exist free living in the rhizosphere. Crucial to their complex lifestyle is the ability to sense and respond to diverse environmental stimuli, requiring elaborate signaling pathways. In the majority of bacteria, the nucleotide-based second messenger cyclic diguanosine monophosphate (c-di-GMP) is involved in signal transduction. Surprisingly, little is known about the importance of c-di-GMP signaling in rhizobia. We have analyzed the genome sequences of six well-studied type species (Bradyrhizobium japonicum, Mesorhizobium loti, Rhizobium etli, Rhizobium leguminosarum, Sinorhizobium fredii, and Sinorhizobium meliloti) for proteins possibly involved in c-di-GMP signaling based on the presence of four domains: GGDEF (diguanylate cyclase), EAL and HD-GYP (phosphodiesterase), and PilZ (c-di-GMP sensor). We find that rhizobia possess a high number of these proteins. Conservation analysis suggests that c-di-GMP signaling proteins modulate species-specific pathways rather than ancient rhizobia-specific processes. Two hybrid GGDEF-EAL proteins were selected for functional analysis, R. etli RHE_PD00105 (CdgA) and RHE_PD00137 (CdgB). Expression of cdgA and cdgB is repressed by the alarmone (p)ppGpp. cdgB is significantly expressed on plant roots and free living. Mutation of cdgA, cdgB, or both does not affect plant root colonization, nitrogen fixation capacity, biofilm formation, motility, and exopolysaccharide production. However, heterologous expression of the individual GGDEF and EAL domains of each protein in Escherichia coli strongly suggests that CdgA and CdgB are bifunctional proteins, possessing both diguanylate cyclase and phosphodiesterase activities. Taken together, our results provide a platform for future studies of c-di-GMP signaling in rhizobia.

  11. Effect of Naturally Occurring nif Reiterations on Symbiotic Effectiveness in Rhizobium phaseoli

    Science.gov (United States)

    Romero, David; Singleton, Paul W.; Segovia, Lorenzo; Morett, Enrique; Bohlool, B. Ben; Palacios, Rafael; Dávila, Guillermo

    1988-01-01

    Most naturally occurring strains of Rhizobium phaseoli possess reiteration of the nif genes. Three regions contain nitrogenase structural genes in strain CFN42. Two of these regions (a and b) have copies of nifH, nifD, and nifK, whereas the third region (c) contains only nifH. Strains containing mutations in either nif region a or nif region b had significantly diminished symbiotic effectiveness compared with the wild-type strain on the basis of nodule mass, total nitrogenase activity per plant, nitrogenase specific activity, total nitrogen in the shoot, and percentage of nitrogen. A strain containing mutations in both nif region a and nif region b was totally ineffective. These data indicate that both nif region a and nif region b are needed for full symbiotic effectiveness in R. phaseoli. PMID:16347593

  12. Effet de la co-inoculation du rhizobium et de mycorhizes sur les ...

    African Journals Online (AJOL)

    SARAH

    30 déc. 2013 ... Les résultats obtenus présentent un intérêt pratique et l'étude doit être poursuivie en vue d'évaluer l'impact de .... cas contraire, l'analyse prend fin et l'on considère que les ..... deuxième réunion de la coordination du projet.

  13. Region 4 of Rhizobium etli Primary Sigma Factor (SigA) Confers Transcriptional Laxity in Escherichia coli

    Science.gov (United States)

    Santillán, Orlando; Ramírez-Romero, Miguel A.; Lozano, Luis; Checa, Alberto; Encarnación, Sergio M.; Dávila, Guillermo

    2016-01-01

    Sigma factors are RNA polymerase subunits engaged in promoter recognition and DNA strand separation during transcription initiation in bacteria. Primary sigma factors are responsible for the expression of housekeeping genes and are essential for survival. RpoD, the primary sigma factor of Escherichia coli, a γ-proteobacteria, recognizes consensus promoter sequences highly similar to those of some α-proteobacteria species. Despite this resemblance, RpoD is unable to sustain transcription from most of the α-proteobacterial promoters tested so far. In contrast, we have found that SigA, the primary sigma factor of Rhizobium etli, an α-proteobacteria, is able to transcribe E. coli promoters, although it exhibits only 48% identity (98% coverage) to RpoD. We have called this the transcriptional laxity phenomenon. Here, we show that SigA partially complements the thermo-sensitive deficiency of RpoD285 from E. coli strain UQ285 and that the SigA region σ4 is responsible for this phenotype. Sixteen out of 74 residues (21.6%) within region σ4 are variable between RpoD and SigA. Mutating these residues significantly improves SigA ability to complement E. coli UQ285. Only six of these residues fall into positions already known to interact with promoter DNA and to comprise a helix-turn-helix motif. The remaining variable positions are located on previously unexplored sites inside region σ4, specifically into the first two α-helices of the region. Neither of the variable positions confined to these helices seem to interact directly with promoter sequence; instead, we adduce that these residues participate allosterically by contributing to correct region folding and/or positioning of the HTH motif. We propose that transcriptional laxity is a mechanism for ensuring transcription in spite of naturally occurring mutations from endogenous promoters and/or horizontally transferred DNA sequences, allowing survival and fast environmental adaptation of α-proteobacteria. PMID

  14. The Rhizobium etli rpoN Locus: DNA Sequence Analysis and Phenotypical Characterization of rpoN, ptsN, and ptsA Mutants

    OpenAIRE

    Michiels, Jan; Van Soom, Tom; D’hooghe, Inge; Dombrecht, Bruno; Benhassine,Traki; Wilde, Petra; Vanderleyden, Jos

    1998-01-01

    The rpoN region of Rhizobium etli was isolated by using the Bradyrhizobium japonicum rpoN1 gene as a probe. Nucleotide sequence analysis of a 5,600-bp DNA fragment of this region revealed the presence of four complete open reading frames (ORFs), ORF258, rpoN, ORF191, and ptsN, coding for proteins of 258, 520, 191, and 154 amino acids, respectively. The gene product of ORF258 is homologous to members of the ATP-binding cassette-type permeases. ORF191 and ptsN are homologous to conserved ORFs f...

  15. The Rhizobium etli rpoN Locus: DNA Sequence Analysis and Phenotypical Characterization of rpoN, ptsN, and ptsA Mutants

    OpenAIRE

    Michiels, Jan; Van Soom, Tom; D’hooghe, Inge; Dombrecht, Bruno; Benhassine, Traki; Wilde, Petra; Vanderleyden, Jos

    1998-01-01

    The rpoN region of Rhizobium etli was isolated by using the Bradyrhizobium japonicum rpoN1 gene as a probe. Nucleotide sequence analysis of a 5,600-bp DNA fragment of this region revealed the presence of four complete open reading frames (ORFs), ORF258, rpoN, ORF191, and ptsN, coding for proteins of 258, 520, 191, and 154 amino acids, respectively. The gene product of ORF258 is homologous to members of the ATP-binding cassette-type permeases. ORF191 and ptsN are homologous to conserved ORFs f...

  16. Influence of plant species on the biological control activity of the antagonistic rhizobacterium Rhizobium etli strain G12 toward the root-knot nematode, Meloidogyne incognita.

    Science.gov (United States)

    Mahdy, M; Hallmann, J; Sikora, R A

    2001-01-01

    The influence of plant species on the antagonistic activity of the rhizosphere bacterium Rhizobium etli G12 towards the root-knot nematode Meloidogyne incognita was studied. The crops tested were tomato, cucumber, cotton, soybean and pepper. The plants were evaluated for the following parameters: root gall-index, total number of galls and egg masses of M. incognita, as well as shoot and root fresh weight and root length. Results indicated a clear influence of plant species on the ability of R. etli G12 to reduce nematode infection. Based on the root gall index, nematode control by R. etli G12 was higher on vegetables (tomato, cucumber, pepper) than on field crops (soybean, cotton). Reduction in galling ranged from 17% for cotton to 50% for tomato. R. etli G12 also reduced the actual number of galls produced. The reduction in the number of galls produced between crops was not affected significantly as was seen when a galling index was used to measure activity. The reduction in the number of galls was similar in level for all the crops studied and ranged from 34% for cucumber to 47% for tomato. There was a significant reduction in the number of egg masses produced by the females ranging from 37% for soybean to 70% for pepper. This indicated a direct effect on female development in the root after penetration or delayed penetration on certain crops. The bacteria caused significant increases in shoot fresh weight from 11% for soybean to 31% for pepper and in root fresh weight from 3% for soybean to 39% for tomato and in root length from 11% for cucumber to 24% for pepper. R. etli G12 gave significant control of M. incognita on a broad range of host plants, but the level of control varied. The suitability of each plant species, therefore, must be examined before R. etli G12 can be recommend for control of this nematode.

  17. Biostimulation of soil polluted 10000 ppm of waste motor oil and phytoremediation with Cicer arietinum improved by Bacillus cereus/Rhizobium etli

    Directory of Open Access Journals (Sweden)

    Juárez-Cisneros Gladys

    2016-08-01

    Full Text Available Soil pollution by waste motor oil (WMO is reducing its productivity. An alternative for removing WMO from soil is by biostimulation (BIS applying animal manure and then phytoremediation (PR by legume improving with plant growth promoting bacteria (PGPB to reduce WMO concentration at level below 4400 ppm limit permit for the NOM-138-SEMARNAT/SSA1-2012 (NOM-138. The aims of this re-search were: i to analyze soil biostimulation polluted by 10000 ppm of WMO applying vermicompost, then subsequent soil phytoremediation with Cicer arietinum inoculated by Bacillus cereus and/or Rhizo-bium etli. In soil after applying BS by VC was measured WMO soil concentration and ii for PR was regarded phenology and biomass of C. arietinum and WMO concentration remaining at the end of this step. The results showed that soil biostimulated by VC, WMO was reduced at 1370 ppm, subsequent PR sowing C. arietinum with R. etli, WMR was reduced at 30 ppm concentration both values below to maxi-mum value accepted by NOM-138. Those data indicate that in soil polluted by WMO the best way to biorecovery soil was to integrate strategy BS/PR the last one improved by genus of PGPB.

  18. Biorestauration of soil polluted by waste motor oil by biostimulation with vermicompost and phytoremediation with Sorghum vulgare inoculated by Bacillus cereus and Rhizobium etli

    Directory of Open Access Journals (Sweden)

    Juárez-Cisneros Gladys

    2014-11-01

    Full Text Available Soil pollution by waste motor oil (WMO caused soil´s lost fertility. The aims of this research where a bioremediation of soil polluted by 10000 ppm of WMO for biostimulation with vermicompost (VC at 3 and 6 % (w/w follow by b phytoremediation (PR of the same soil to eliminate remaining WMO with Sorghum vulgare inoculated with Bacillus cereus and/or Rhizobium etli or Promoting Growth Plant Bacteria (PGPB. At the first step of assay WMO concentration was measured before and after bioremediation. At the second step the same soil phytoremediation was applied for remaining WHO sowing S. vulgare inoculated with PGPB, then at flowering stage its biomass and WHO final concentration was determined. Results showed that soil impacted by WMO biostimulated with VC at 3% was eliminated 8630 ppm of WMO. At the second phase in the same soil PR applied for remaining WMO which was reduced until 210 ppm. Soil polluted by remaining WMO applied PR using S. vulgare plus R. etli WMO was decreased at 260 ppm. While S. vulgare´s biomass inoculated with PGPB was higher compared to S. vulgare grown in soil not polluted by WMO according by ANOVA - Tukey (p > 0.05. These results suggested that soil polluted by WMO could be recovering by applying integrated BR and PR better than just using one type.

  19. Biochemical characterization of recombinant L-asparaginase (AnsA) from Rhizobium etli, a member of an increasing rhizobial-type family of L-asparaginases.

    Science.gov (United States)

    Moreno-Enriquez, Angelica; Evangelista-Martinez, Zahaed; Gonzalez-Mondragon, Edith G; Calderon-Flores, Arturo; Arreguin, Roberto; Perez-Rueda, Ernesto; Huerta-Saquero, Alejandro

    2012-03-01

    We report the expression, purification, and characterization of L-asparaginase (AnsA) from Rhizobium etli. The enzyme was purified to homogeneity in a single-step procedure involving affinity chromatography, and the kinetic parameters K(m), V(max), and k(cat) for L-asparagine were determined. The enzymatic activity in the presence of a number of substrates and metal ions was investigated. The molecular mass of the enzyme was 47 kDa by SDS-PAGE. The enzyme showed a maximal activity at 50 degrees C, but the optimal temperature of activity was 37 degrees C. It also showed maximal and optimal activities at pH 9.0. The values of K(m), V(max), k(cat), and k(cat)/K(m) were 8.9 +/- 0.967 × 10⁻³ M, 128 +/- 2.8 U/mg protein, 106 +/- 2 s⁻¹, and 1.2 +/- 0.105 × 10⁴ M⁻¹s⁻¹, respectively. The L-asparaginase activity was reduced in the presence of Mn²⁺, Zn²⁺, Ca²⁺, and Mg²⁺ metal ions for about 52% to 31%. In addition, we found that NH₄⁺, L-Asp, D-Asn, and beta-aspartyl-hydroxamate in the reaction buffer reduced the activity of the enzyme, whereas L-Gln did not modify its enzymatic activity. This is the first report on the expression and characterization of the L-asparaginase (AnsA) from R. etli. Phylogenetic analysis of asparaginases reveals an increasing group of known sequences of the Rhizobialtype asparaginase II family.

  20. A revision of Rhizobium Frank 1889, with an emended description of the genus, and the inclusion of all species of Agrobacterium Conn 1942 and Allorhizobium undicola de Lajudie et al. 1998 as new combinations: Rhizobium radiobacter, R. rhizogenes, R. rubi, R. undicola and R. vitis.

    Science.gov (United States)

    Young, J M; Kuykendall, L D; Martínez-Romero, E; Kerr, A; Sawada, H

    2001-01-01

    Rhizobium, Agrobacterium and Allorhizobium are genera within the bacterial family Rhizobiaceae, together with Sinorhizobium. The species of Agrobacterium, Agrobacterium tumefaciens (syn. Agrobacterium radiobacter), Agrobacterium rhizogenes, Agrobacterium rubi and Agrobacterium vitis, together with Allorhizobium undicola, form a monophyletic group with all Rhizobium species, based on comparative 16S rDNA analyses. Agrobacterium is an artificial genus comprising plant-pathogenic species. The monophyletic nature of Agrobacterium, Allorhizobium and Rhizobium and their common phenotypic generic circumscription support their amalgamation into a single genus, Rhizobium. Agrobacterium tumefaciens was conserved as the type species of Agrobacterium, but the epithet radiobacter would take precedence as Rhizobium radiobacter in the revised genus. The proposed new combinations are Rhizobium radiobacter, Rhizobium rhizogenes, Rhizobium rubi, Rhizobium undicola and Rhizobium vitis.

  1. Evolution of rhizobium symbiosis

    NARCIS (Netherlands)

    Camp, Op den R.H.M.

    2012-01-01

    The evolution of rhizobium symbiosis is studied from several points of view in this thesis. The ultimate goal of the combined approaches is to unravel the genetic constrains of the symbiotic interaction. To this end the legume rhizobium symbiosis is studied in model plant species from the Papilionoi

  2. Evolution of rhizobium symbiosis

    NARCIS (Netherlands)

    Camp, Op den R.H.M.

    2012-01-01

    The evolution of rhizobium symbiosis is studied from several points of view in this thesis. The ultimate goal of the combined approaches is to unravel the genetic constrains of the symbiotic interaction. To this end the legume rhizobium symbiosis is studied in model plant species from the

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

    Directory of Open Access Journals (Sweden)

    Lachaâl M.

    2009-01-01

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

  4. Elucidation of the 3-O-deacylase gene, pagL, required for the removal of primary β-hydroxy fatty acid from the lipid A in the nitrogen-fixing endosymbiont Rhizobium etli CE3.

    Science.gov (United States)

    Brown, Dusty B; Muszynski, Artur; Salas, Omar; Speed, Kacie; Carlson, Russell W

    2013-04-26

    Until now, the gene responsible for the 3-O-deacylation of lipid A among nitrogen-fixing endosymbionts has not been characterized. Several Gram-negative animal pathogens such as Salmonella enterica, Pseudomonas aeruginosa, and Bordetella bronchiseptica contain an outer membrane 3-O-deacylase (PagL) that has been implicated in host immune evasion. The role of 3-O-deacylated lipid A among nitrogen-fixing endosymbionts, plant endophytes, and plant pathogens has not been studied. However, D'Haeze et al. (D'Haeze, W., Leoff, C., Freshour, G., Noel, K. D., and Carlson, R. W. (2007) J. Biol. Chem. 282, 17101-17113) reported that the lipopolysaccharide from Rhizobium etli CE3 bacteroids isolated from host bean root nodules contained exclusively tetraacylated lipid A that lacked a lipid A β-hydroxymyristyl residue, an observation that is consistent with the possibility of PagL activity being important in symbiosis. A putative pagL gene was identified in the R. etli genome sequence. With this information, we created a pagL(-) mutant strain derived from R. etli CE3. Using mass spectrometry, we demonstrated that the mutant lacks 3-O-deacylated lipid A. The parent and mutant LPS were very similar as determined by gel electrophoresis and glycosyl composition analysis using gas chromatography/mass spectrometry. However, fatty acid analysis showed that the mutant lipid A contained larger amounts of β-hydroxypentadecanoic acid than that of the parent. Furthermore, the mutant was adversely affected in establishing symbiosis with its host, Phaseolus vulgaris.

  5. CYCLOPS: a new vision on rhizobium-induced nodule organogenesis : Preview

    NARCIS (Netherlands)

    Limpens, E.H.M.; Bisseling, T.

    2014-01-01

    The accommodation of nitrogen-fixing rhizobium bacteria inside plant cells requires reprogramming of root cortex cells by rhizobial signals. In this issue of Cell Host & Microbe, Singh et al. (2014) reveal that CYCLOPS, representing a novel class of transcription factors, links rhizobium-induced

  6. Nodulation ability of the common bean genotypes composing the BASE 120 trial after inoculation with Rhizobium

    Science.gov (United States)

    This study examined the nodulation characteristics of the BASE 120 genotypes in a trial of 118 common bean (Phaseolus vulgaris L.) and two tepary bean (Phaseolus acutifolius) lines. Inoculation with Rhizobium tropici strain CIAT 899 and Rhizobium etli strain CIAT 632 was carried out in a screenhouse...

  7. A revision of Rhizobium Frank 1889, with an emended description of the genus, and the inclusion of all species of Agrobacterium Conn 1942 and Allorhizobium undicola de Lajudie et al. 1998 as new combinations: Rhizobium radiobacter, R. rhizogenes, R. rubi, R. undicola and R. vitis

    National Research Council Canada - National Science Library

    Young, JM; Kuykendall, LD; Martinez-Romero, E; Kerr, A; Sawada, H

    2001-01-01

    .... Agrobacterium radiobacter), Agrobacterium rhizogenes, Agrobacterium rubi and Agrobacterium vitis, together with Allorhizobium undicola, form a monophyletic group with all Rhizobium species, based on comparative 16S rDNA analyses...

  8. Genome-wide detection of predicted non-coding RNAs in Rhizobium etli expressed during free-living and host-associated growth using a high-resolution tiling array

    Directory of Open Access Journals (Sweden)

    Thijs Inge M

    2010-01-01

    Full Text Available Abstract Background Non-coding RNAs (ncRNAs play a crucial role in the intricate regulation of bacterial gene expression, allowing bacteria to quickly adapt to changing environments. In the past few years, a growing number of regulatory RNA elements have been predicted by computational methods, mostly in well-studied γ-proteobacteria but lately in several α-proteobacteria as well. Here, we have compared an extensive compilation of these non-coding RNA predictions to intergenic expression data of a whole-genome high-resolution tiling array in the soil-dwelling α-proteobacterium Rhizobium etli. Results Expression of 89 candidate ncRNAs was detected, both on the chromosome and on the six megaplasmids encompassing the R. etli genome. Of these, 11 correspond to functionally well characterized ncRNAs, 12 were previously identified in other α-proteobacteria but are as yet uncharacterized and 66 were computationally predicted earlier but had not been experimentally identified and were therefore classified as novel ncRNAs. The latter comprise 17 putative sRNAs and 49 putative cis-regulatory ncRNAs. A selection of these candidate ncRNAs was validated by RT-qPCR, Northern blotting and 5' RACE, confirming the existence of 4 ncRNAs. Interestingly, individual transcript levels of numerous ncRNAs varied during free-living growth and during interaction with the eukaryotic host plant, pointing to possible ncRNA-dependent regulation of these specialized processes. Conclusions Our data support the practical value of previous ncRNA prediction algorithms and significantly expand the list of candidate ncRNAs encoded in the intergenic regions of R. etli and, by extension, of α-proteobacteria. Moreover, we show high-resolution tiling arrays to be suitable tools for studying intergenic ncRNA transcription profiles across the genome. The differential expression levels of some of these ncRNAs may indicate a role in adaptation to changing environmental conditions.

  9. Identification of the σ⁷⁰-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 σ(70) transcription factor. Mutation studies affecting several regions located upstream of the transcriptional start site confirmed the importance of these elements on transcriptional expression.

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

    Science.gov (United States)

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

    2015-09-01

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

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

    NARCIS (Netherlands)

    Breedveld, M.W.

    1992-01-01

    Rhizobium and Agrobacterium species are capable of synthesizing a variety of extracellular and cellular oligo- and polysaccharides. Changes in environmental conditions may all affect the composition, physical properties, and relative amounts of

  12. Symbiotic potential and survival of native rhizobia kept on different carriers

    Science.gov (United States)

    Ruíz-Valdiviezo, Víctor Manuel; Canseco, Lucía María Cristina Ventura; Suárez, Luis Antonio Castillo; Gutiérrez-Miceli, Federico Antonio; Dendooven, Luc; Rincón-Rosales, Reiner

    2015-01-01

    Native rhizobia are ideal for use as commercial legume inoculants. The characteristics of the carrier used to store the inoculants are important for the survival and symbiotic potential of the rhizobia. The objective of this study was to investigate the effects of peat (PEAT), perlite sugarcane bagasse (PSB), carboxymethyl cellulose plus starch (CMCS), and yeast extract mannitol supplemented with mannitol (YEMM) on the survival, nodulation potential and N2 fixation capacity of the native strains Sinorhizobium mexicanum ITTG R7T and Rhizobium calliandrae LBP2-1T and of the reference strain Rhizobium etli CFN42T. A factorial design (4 × 3) with four repetitions was used to determine the symbiotic potential of the rhizobial strains. The survival of the strains was higher for PEAT (46% for strain LBP2-1T, 167% for strain CFN42T and 219% for strain ITTG R7T) than for the other carriers after 240 days, except for CFN42T kept on CMCS (225%). All the strains kept on the different carriers effectively nodulated common bean, with the lowest number of nodules found (5 nodules) when CFN42T was kept on CMCS and with the highest number of nodules found (28 nodules) when ITTG R7T was kept on PSB. The nitrogenase activity was the highest for ITTG R7T kept on PEAT (4911 μmol C2H4 per fresh weight nodule h−1); however, no activity was found when the strains were kept on YEMM. Thus, the survival and symbiotic potential of the rhizobia depended on the carrier used to store them. PMID:26413054

  13. Symbiotic potential and survival of native rhizobia kept on different carriers.

    Science.gov (United States)

    Ruíz-Valdiviezo, Víctor Manuel; Canseco, Lucía María Cristina Ventura; Suárez, Luis Antonio Castillo; Gutiérrez-Miceli, Federico Antonio; Dendooven, Luc; Rincón-Rosales, Reiner

    2015-01-01

    Native rhizobia are ideal for use as commercial legume inoculants. The characteristics of the carrier used to store the inoculants are important for the survival and symbiotic potential of the rhizobia. The objective of this study was to investigate the effects of peat (PEAT), perlite sugarcane bagasse (PSB), carboxymethyl cellulose plus starch (CMCS), and yeast extract mannitol supplemented with mannitol (YEMM) on the survival, nodulation potential and N2 fixation capacity of the native strains Sinorhizobium mexicanum ITTG R7(T) and Rhizobium calliandrae LBP2-1(T) and of the reference strain Rhizobium etli CFN42(T). A factorial design (4 × 3) with four repetitions was used to determine the symbiotic potential of the rhizobial strains. The survival of the strains was higher for PEAT (46% for strain LBP2-1(T), 167% for strain CFN42(T) and 219% for strain ITTG R7(T)) than for the other carriers after 240 days, except for CFN42(T) kept on CMCS (225%). All the strains kept on the different carriers effectively nodulated common bean, with the lowest number of nodules found (5 nodules) when CFN42(T) was kept on CMCS and with the highest number of nodules found (28 nodules) when ITTG R7(T) was kept on PSB. The nitrogenase activity was the highest for ITTG R7(T) kept on PEAT (4911 μmol C2H4 per fresh weight nodule h(-1)); however, no activity was found when the strains were kept on YEMM. Thus, the survival and symbiotic potential of the rhizobia depended on the carrier used to store them.

  14. Symbiotic potential and survival of native rhizobia kept on different carriers

    Directory of Open Access Journals (Sweden)

    Víctor Manuel Ruíz-Valdiviezo

    2015-09-01

    Full Text Available Native rhizobia are ideal for use as commercial legume inoculants. The characteristics of the carrier used to store the inoculants are important for the survival and symbiotic potential of the rhizobia. The objective of this study was to investigate the effects of peat (PEAT, perlite sugarcane bagasse (PSB, carboxymethyl cellulose plus starch (CMCS, and yeast extract mannitol supplemented with mannitol (YEMM on the survival, nodulation potential and N2 fixation capacity of the native strains Sinorhizobium mexicanum ITTG R7T and Rhizobium calliandrae LBP2-1T and of the reference strain Rhizobium etli CFN42T. A factorial design (4 × 3 with four repetitions was used to determine the symbiotic potential of the rhizobial strains. The survival of the strains was higher for PEAT (46% for strain LBP2-1T, 167% for strain CFN42T and 219% for strain ITTG R7T than for the other carriers after 240 days, except for CFN42T kept on CMCS (225%. All the strains kept on the different carriers effectively nodulated common bean, with the lowest number of nodules found (5 nodules when CFN42T was kept on CMCS and with the highest number of nodules found (28 nodules when ITTG R7T was kept on PSB. The nitrogenase activity was the highest for ITTG R7T kept on PEAT (4911 μmol C2H4 per fresh weight nodule h−1; however, no activity was found when the strains were kept on YEMM. Thus, the survival and symbiotic potential of the rhizobia depended on the carrier used to store them.

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

    OpenAIRE

    Breedveld, M W

    1992-01-01

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

  16. Novel Rhizobium lineages isolated from root nodules of the common bean (Phaseolus vulgaris L.) in Andean and Mesoamerican areas.

    Science.gov (United States)

    Ribeiro, Renan Augusto; Ormeño-Orrillo, Ernesto; Dall'Agnol, Rebeca Fuzinatto; Graham, Peter H; Martinez-Romero, Esperanza; Hungria, Mariangela

    2013-09-01

    The taxonomic affiliations of nineteen root-nodule bacteria isolated from the common bean (Phaseolus vulgaris L.) in Mexico, Ecuador and Brazil were investigated by analyses of 16S rRNA and of four protein-coding housekeeping genes. One strain from Mexico could be assigned to Rhizobium etli and two from Brazil to Rhizobium leucaenae, whereas another from Mexico corresponded to a recently described bean-nodulating species-level lineage related to R. etli and Rhizobium phaseoli. Ten strains isolated in Ecuador and Mexico corresponded to three novel Rhizobium lineages that fall into the R. phaseoli/R. etli/Rhizobium leguminosarum clade. One of those lineages, with representatives isolated mostly from Ecuador, seems to be dominant in beans from that Andean region. Only one of the Mexican strains clustered within the Rhizobium tropici clade, but as an independent lineage. Interestingly, four strains were affiliated with species within the Rhizobium radiobacter clade. The existence of yet non-described native Rhizobium lineages in both the Andean and Mesoamerican areas is discussed in relation to common-bean diversity and environmental conditions.

  17. 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.

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

    NARCIS (Netherlands)

    Breedveld, M.W.

    1992-01-01

    Rhizobium and Agrobacterium species are capable of synthesizing a variety of extracellular and cellular oligo- and polysaccharides. Changes in environmental conditions may all affect the composition, physical properties, and relative amounts of oligo- and polysaccharides. Interest in the field of Rh

  19. 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

  20. The celC gene, a new phylogenetic marker useful for taxonomic studies in Rhizobium.

    Science.gov (United States)

    Robledo, Marta; Velázquez, Encarna; Ramírez-Bahena, Martha Helena; García-Fraile, Paula; Pérez-Alonso, Ana; Rivas, Raúl; Martínez-Molina, Eustoquio; Mateos, Pedro F

    2011-09-01

    The celC gene codifies for a cellulase that fulfils a very significant role in the infection process of clover by Rhizobium leguminosarum. This gene is located in the celABC operon present in the chromosome of strains representing R. leguminosarum, Rhizobium etli and Rhizobium radiobacter whose genomes have been completely sequenced. Nevertheless, the existence of this gene in other species of the genus Rhizobium had not been investigated to date. In this study, the celC gene was analysed for the first time in several species of this genus isolated from legume nodules and plant tumours, in order to compare the celC phylogeny to those of other chromosomal and plasmidic genes. The results obtained showed that phylogenies of celC and chromosomal genes, such as rrs, recA and atpD, were completely congruent, whereas no relation was found with symbiotic or virulence genes. Therefore, the suitability and usefulness of the celC gene to differentiate species of the genus Rhizobium, especially those with closely related rrs genes, was highlighted. Consequently, the taxonomic status of several strains of the genus Rhizobium with completely sequenced genomes is also discussed.

  1. Phylogenetic diversity based on rrs, atpD, recA genes and 16S-23S intergenic sequence analyses of rhizobial strains isolated from Vicia faba and Pisum sativum in Peru.

    Science.gov (United States)

    Santillana, Nery; Ramírez-Bahena, Martha Helena; García-Fraile, Paula; Velázquez, Encarna; Zúñiga, Doris

    2008-03-01

    In this study 17 isolates from effective nodules of Vicia faba and Pisum sativum var. macrocarpum growing in different soils from Peru were isolated and characterized. The isolates, presenting 11 different RAPD profiles, were distributed in three groups on the basis of their 16S-RFLP patterns. The 16S rRNA gene sequences of strains from 16S-RFLP groups I, II and III were closely related (identities higher than 99.5%) to Rhizobium leguminosarum bv. trifolii DSM 30141 (=ATCC 14480), R. leguminosarum bv. viciae DSM 30132(T) and Rhizobium etli CFN42(T) (=USDA 9032(T)), respectively. The analysis of the 16S-23S intergenic spacer (ITS) and two housekeeping genes, atpD and recA, confirmed the identification of strains from group I, however those from groups II and III were phylogenetically divergent to strains DSM 30132(T) and CFN42(T). These results support the fact that the 16S rRNA gene is not adequate for identification at species level within genus Rhizobium and suggest the existence of putative new species within the phylogenetic group of R. leguminosarum. They also confirm the need of a taxonomic revision of R. leguminosarum since the reference strains of the three biovars included in this study are phylogenetically divergent according to their ITS, atpD and recA gene sequences.

  2. Spécificité de la symbiose Rhizobium-Pterocarpus au Sénégal

    OpenAIRE

    Sylla, E.H.S.N.; Ndoye, I.; Bâ, A.T.; Dreyfus, Bernard

    1997-01-01

    Soixante-dix souches de #Rhizobium$ ont été isolées à partir de nodules racinaires de #Pterocarpus erinaceus$ Poir. et #Pterocarpus lucens$ Lepr. Les souches ont été caractérisées par l'étude de leur croissance, de leur résistance aux antibiotiques, de leur cinétique de nodulation, de leur spectre d'hôte et de leur effectivité. Deux groupes bien distincts de souches ont été identifiés : des Rhizobiums à croissance rapide et des Rhizobiums à croissance lente. Les tests d'inoculation ont montré...

  3. Genetic diversity of root-nodulating bacteria isolated from pea (Pisum sativum) in subtropical regions of China

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Diversity of 42 isolates from effective nodules of Pisum sativum in different geographical regions of China were studied using 16S rRNA gene RFLP patterns, 16S rRNA sequencing, 16S–23S rRNA inter-genic spacer (IGS) region RFLP patterns and G-C rich random amplified polymorphic DNA (RAPD). The isolates were distributed in two groups on the basis of their 16S rRNA gene RFLP patterns. The 16S rRNA gene sequences of strains from 16S rRNA gene RFLP patterns group I were very closely related (identities higher than 99.5%) to Rhizobium leguminosarum USDA 2370. Group II consisting of WzP3 and WzP15 was closely related to Rhizobium etli CFN42. The analysis of the 16S–23S IGS RFLP pat-terns divided the isolates into 18 genotypes and four groups. Group I was clustered with R. legumino-sarum USDA2370. Group II consisted of YcP2, YcP3 and CqP7. The strains of group III were distributed abroad. Group IV consisted of WzP3, WzP15 and R. etli CFN42. RAPD divided the isolates into nine clusters in which group IV only consisted of YcP2 and the strains of group V and IX were from Wenzhou and Xiantao, respectively. This assay demonstrated the geographical effect on genetic diversity of pea rhizobia.

  4. Genetic diversity of root-nodulating bacteria isolated from pea (Pisum sativum) in subtropical regions of China

    Institute of Scientific and Technical Information of China (English)

    YANG ChengYun; YANG JiangKe; LI YouGuo; ZHOU JunOhu

    2008-01-01

    Diversity of 42 isolates from effective nodules of Pisum sativum in different geographical regions of China were studied using 16S rRNA gene RFLP patterns, 16S rRNA sequencing, 16S-23S rRNA inter-genic spacer (IGS) region RFLP patterns and G-C rich random amplified polymorphic DNA (RAPD). The isolates were distributed in two groups on the basis of their 16S rRNA gene RFLP patterns. The 16S rRNA gene sequences of strains from 16S rRNA gene RFLP patterns group Ⅰ were very closely related (identities higher than 99.5%) to Rhizobium leguminosarum USDA 2370. Group Ⅱ consisting of WzP3 and WzP15 was closely related to Rhizobium etli CFN42. The analysis of the 16S-23S IGS RFLP pat-terns divided the isolates into 18 genotypes and four groups. Group Ⅰ was clustered with R. legumino-sarum USDA2370. Group Ⅱ consisted of YcP2, YcP3 and CqP7. The strains of group Ⅲ were distributed abroad. Group Ⅳ consisted of WzP3, WzP15 and R. etli CFN42. RAPD divided the isolates into nine clusters in which group Ⅳ only consisted of YcP2 and the strains of group Ⅴ and Ⅸ were from Wenzhou and Xiantao, respectively. This assay demonstrated the geographical effect on genetic diversity of pea rhizobia.

  5. 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 : 1ω7c, 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

  6. 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 ( Rhizobium fabae. DNA-DNA hybridization ( Rhizobium ecuadorense sp. nov. The type strain is CNPSo 671(T) ( = UMR 1450(T) = PIMAMPIRS I 5(T) = LMG 27578(T)).

  7. Response of Phaseolus vulgaris cv. Mantequilla to inoculation of Rhizobium native strains of the Ecuador in greenhouse native races of the Ecuador

    Directory of Open Access Journals (Sweden)

    Klever Iván Granda Mora

    2016-10-01

    Full Text Available The development of biofertilizers based on Rhizobium strains for common bean (Phaseolus vulgaris L. requires studies about bacterial interaction with target cultivars. For these reason, the aim of this paper was to determine the effect of the inoculation of Rhizobium native strains, isolated from southern Ecuador, on P. vulgaris cultivar Mantequilla. An assay was performed in greenhouse. It were evaluated the parameters of nodulation, biomass, nitrogen fixation and efficiency of the symbiosis. All inoculated strains were able to nodulate bean seedlings. The total number of nodules, nodular biomass and plant biomass, were favourably affected by inoculation of Rhizobium strains. The best results were obtained with R. mesoamericanum NAM1, R. leguminosarum COL 6 and R. etli PIN 1 strains. The experimental evidences shows the potential of native strains of Rhizobium for it use as biofertilizers because they are able to raise the rates of nitrogen fixation in common bean in southern Ecuador.

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

    National Research Council Canada - National Science Library

    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

    2012-01-01

    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...

  9. Preliminary characterization of Rhizobium strains isolated from ...

    African Journals Online (AJOL)

    SERVER

    2008-03-18

    Mar 18, 2008 ... about the efficiency of crop inoculation (Graham, 1981;. Hardarson, 1993 ... Strains of Rhizobium sp. were obtained from root nodules of field grown chickpea plants .... 3.0 and 9.0 (Table 1), as observed for other R. ciceri.

  10. Evolutionary origin of rhizobium Nod factor signaling

    NARCIS (Netherlands)

    Streng, A.; Camp, Op den R.; Bisseling, T.; Geurts, R.

    2011-01-01

    For over two decades now, it is known that the nodule symbiosis between legume plants and nitrogen fixing rhizobium bacteria is set in motion by the bacterial signal molecule named nodulation (Nod) factor.1 Upon Nod factor perception a signaling cascade is activated that is also essential for endomy

  11. Transposon Tn5 specifies streptomycin resistance in Rhizobium spp.

    OpenAIRE

    1984-01-01

    Transposon Tn5 conferred streptomycin resistance on different strains of Rhizobium meliloti, Rhizobium leguminosarum, and Rhizobium trifolii but not on Escherichia coli. A gene (str) specifying this phenotype has been identified and localized on the physical and genetic map of Tn5. It is transcribed from the promoter of neo, the gene that encodes neomycin phosphotransferase. The str gene is downstream from neo in a single transcriptional unit, as revealed by molecular cloning of different seg...

  12. Nif- Hup- mutants of Rhizobium japonicum.

    OpenAIRE

    Moshiri, F; Stults, L; Novak, P.; Maier, R J

    1983-01-01

    Two H2 uptake-negative (Hup-) Rhizobium japonicum mutants were obtained that also lacked symbiotic N2 fixation (acetylene reduction) activity. One of the mutants formed green nodules and was deficient in heme. Hydrogen oxidation activity in this mutant could be restored by the addition of heme plus ATP to crude extracts. Bacteroid extracts from the other mutant strain lacked hydrogenase activity and activity for both of the nitrogenase component proteins. Hup+ revertants of the mutant strains...

  13. Evolutionary origin of rhizobium Nod factor signaling.

    Science.gov (United States)

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

    2011-10-01

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

  14. Immunosuppression during Rhizobium-legume symbiosis.

    Science.gov (United States)

    Luo, Li; Lu, Dawei

    2014-01-01

    Rhizobium infects host legumes to elicit new plant organs, nodules where dinitrogen is fixed as ammonia that can be directly utilized by plants. The nodulation factor (NF) produced by Rhizobium is one of the determinant signals for rhizobial infection and nodule development. Recently, it was found to suppress the innate immunity on host and nonhost plants as well as its analogs, chitins. Therefore, NF can be recognized as a microbe/pathogen-associated molecular pattern (M/PAMP) like chitin to induce the M/PAMP triggered susceptibility (M/PTS) of host plants to rhizobia. Whether the NF signaling pathway is directly associated with the innate immunity is not clear till now. In fact, other MAMPs such as lipopolysaccharide (LPS), exopolysaccharide (EPS) and cyclic-β-glucan, together with type III secretion system (T3SS) effectors are also required for rhizobial infection or survival in leguminous nodule cells. Interestingly, most of them play similarly negative roles in the innate immunity of host plants, though their signaling is not completely elucidated. Taken together, we believe that the local immunosuppression on host plants induced by Rhizobium is essential for the establishment of their symbiosis.

  15. Rhizobium yantingense sp. nov., a mineral-weathering bacterium.

    Science.gov (United States)

    Chen, Wei; Sheng, Xia-Fang; He, Lin-Yan; Huang, Zhi

    2015-02-01

    A Gram-stain-negative, rod-shaped bacterial strain, H66(T), was isolated from the surfaces of weathered rock (purple siltstone) found in Yanting, Sichuan Province, PR China. Cells of strain H66(T) were motile with peritrichous flagella. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain H66(T) belongs to the genus Rhizobium. It is closely related to Rhizobium huautlense SO2(T) (98.1 %), Rhizobium alkalisoli CCBAU 01393(T) (98.0 %) and Rhizobium cellulosilyticum ALA10B2(T) (98.0 %). Analysis of the housekeeping genes, recA, glnII and atpD, showed low levels of sequence similarity (Rhizobium. The predominant components of the cellular fatty acids were summed feature 8 (C18 : 1ω7c and/or C18 : 1ω6c) and C16 : 0. The G+C content of strain H66(T) was 60.3 mol%. Strain H66(T) is suggested to be a novel species of the genus Rhizobium based on the low levels of DNA-DNA relatedness (ranging from 14.3 % to 40.0 %) with type strains of species of the genus Rhizobium and on its unique phenotypic characteristics. The namehttp://dx.doi.org/10.1601/nm.1279Rhizobium yantingense sp. nov. is proposed for this novel species. The type strain is H66(T) ( = CCTCC AB 2014007(T) = LMG 28229(T)).

  16. Effects of phosphate solubilizing microorganisms and Rhizobium sp ...

    African Journals Online (AJOL)

    STORAGESEVER

    2009-08-04

    Aug 4, 2009 ... root-rot disease complex of chickpea under field condition ... Rhizobium sp. compared to plants without Rhizobium sp. Inoculation of P. putida .... 42%, electrical conductivity 0.67, available N 95.90 mg/kg soil, available P 11.4 ...

  17. Draft Genome Sequence of Rhizobium sp. Strain TBD182, an Antagonist of the Plant-Pathogenic Fungus Fusarium oxysporum, Isolated from a Novel Hydroponics System Using Organic Fertilizer.

    Science.gov (United States)

    Iida, Yuichiro; Fujiwara, Kazuki; Someya, Nobutaka; Shinohara, Makoto

    2017-03-16

    Rhizobium sp. strain TBD182, isolated from a novel hydroponics system, is an antagonistic bacterium that inhibits the mycelial growth of Fusarium oxysporum but does not eliminate the pathogen. We report the draft genome sequence of TBD182, which may contribute to elucidation of the molecular mechanisms of its fungistatic activity. Copyright © 2017 Iida et al.

  18. Rhizobium halotolerans sp. nov., Isolated from chloroethylenes contaminated soil.

    Science.gov (United States)

    Diange, Eboa Adolf; Lee, Sang-Seob

    2013-06-01

    The strain designated as AB21(T) was isolated from chloroethylenes contaminated soil. Cells are gram-negative, aerobic, non-spore-forming, and motile rods. Phylogenetic analysis based on 16S rRNA gene sequence showed that it belonged to the genus Rhizobium, and was closely related to Rhizobium sullae IS 123(T) (97.4 %), Rhizobium yanglingense SH 22623(T) (97.2 %), Rhizobium gallicum R 602sp(T) (97.1 %), Rhizobium alamii GBV 016(T) (97.0 %), and Rhizobium monogolense USDA 1844(T) (97.0 %). It showed less than 97 % identity with the remaining Rhizobium species. This novel isolate grew optimally at 25-37 °C (optimum, 30 °C) and pH 6-9 (optimum, pH 8.0). It grew in the presence of 0-4 % (w/v) NaCl, tolerating a 4 % (w/v) NaCl. DNA-DNA hybridization experiment shows less than 53 % binding with closely related Rhizobium. Predominant quinone is ubiquinone (Q-10). The major fatty acids were summed feature 8 (composed of C(18:1) ω7c/C(18:1) ω6c), C(19:0) cyclo ω8c, and C(16:0). The G+C molar content is 62.5 mol%. Based on the polyphasic analysis, strain AB21(T) is referred to be a novel species of the genus Rhizobium for which the name Rhizobium halotolerans sp. nov. is proposed. The type strain is AB21(T) (=KEMC 224-056(T) = JCM 17536(T)).

  19. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Hollingsworth, R.I.

    1991-01-01

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

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

    Science.gov (United States)

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

    2013-09-01

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

  2. Nif- Hup- mutants of Rhizobium japonicum.

    Science.gov (United States)

    Moshiri, F; Stults, L; Novak, P; Maier, R J

    1983-01-01

    Two H2 uptake-negative (Hup-) Rhizobium japonicum mutants were obtained that also lacked symbiotic N2 fixation (acetylene reduction) activity. One of the mutants formed green nodules and was deficient in heme. Hydrogen oxidation activity in this mutant could be restored by the addition of heme plus ATP to crude extracts. Bacteroid extracts from the other mutant strain lacked hydrogenase activity and activity for both of the nitrogenase component proteins. Hup+ revertants of the mutant strains regained both H2 uptake ability and nitrogenase activity. Images PMID:6874648

  3. Characterization of Rhizobium strain isolated from the roots of ...

    African Journals Online (AJOL)

    STORAGESEVER

    2008-10-20

    Oct 20, 2008 ... characterization of a Rhizobium strain isolated from root nodules of fenugreek. ... were rod shaped, gram negative, acid and mucous producing. ... indeed increased biomass yield and enzyme production was observed. The.

  4. Widespread fitness alignment in the legume-rhizobium symbiosis.

    Science.gov (United States)

    Friesen, Maren L

    2012-06-01

    Although 'cheaters' potentially destabilize the legume-rhizobium mutualism, we lack a comprehensive review of host-symbiont fitness correlations. Studies measuring rhizobium relative or absolute fitness and host benefit are surveyed. Mutant studies are tallied for evidence of pleiotropy; studies of natural strains are analyzed with meta-analysis. Of 80 rhizobium mutations, 19 decrease both partners' fitness, four increase both, two increase host fitness but decrease symbiont fitness and none increase symbiont fitness at the host's expense. The pooled correlation between rhizobium nodulation competitiveness and plant aboveground biomass is 0.65 across five experiments that compete natural strains against a reference, whereas, across 14 experiments that compete rhizobia against soil populations or each other, the pooled correlation is 0.24. Pooled correlations between aboveground biomass and nodule number and nodule biomass are 0.76 and 0.83. Positive correlations between legume and rhizobium fitness imply that most ineffective rhizobia are 'defective' rather than 'defectors'; this extends to natural variants, with only one significant fitness conflict. Most studies involve non-coevolved associations, indicating that fitness alignment is the default state. Rhizobium mutations that increase both host and symbiont fitness suggest that some plants maladaptively restrict symbiosis with novel strains.

  5. Optimization of dairy sludge for growth of Rhizobium cells.

    Science.gov (United States)

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

    2013-01-01

    In this study dairy sludge was evaluated as an alternative cultivation medium for Rhizobium. Growth of bacterial strains at different concentrations of Dairy sludge was monitored. Maximum growth of all strains was observed at 60% Dairy sludge concentration. At 60% optical density (OD) values are 0.804 for Rhizobium trifolii (MTCC905), 0.825 for Rhizobium trifolii (MTCC906), and 0.793 for Rhizobium meliloti (MTCC100). Growth pattern of strains was observed at 60% Dairy sludge along with different synthetic media (tryptone yeast, Rhizobium minimal medium and yeast extract mannitol). Growth in 60% Dairy sludge was found to be superior to standard media used for Rhizobium. Media were optimized using 60% dairy sludge along with different concentrations of yeast extract (1-7 g/L) and mannitol (7-13 g/L) in terms of optical density at different time intervals, that is, 24, 48 and 72 hours. Maximum growth was observed in 6 g/L of yeast extract and 12 g/L of mannitol at 48-hour incubation period in all strains. The important environmental parameters such as pH were optimized using 60% dairy sludge, 60% dairy sludge +6 g/L yeast extract, and 60% dairy sludge +12 g/L mannitol. The maximum growth of all strains was found at pH 7.0. The present study recommends the use of 60% dairy sludge as a suitable growth medum for inoculant production.

  6. Rhizobium herbae sp. nov. and Rhizobium giardinii-related bacteria, minor microsymbionts of various wild legumes in China.

    Science.gov (United States)

    Ren, Da Wei; Wang, En Tao; Chen, Wen Feng; Sui, Xin Hua; Zhang, Xiao Xia; Liu, Hong Can; Chen, Wen Xin

    2011-08-01

    Seven Rhizobium strains associated with various legume species grown in different geographical regions of China were defined into four genomic groups related to Rhizobium giardinii, based upon ribosomal intergenic spacer RFLP, phylogenies of 16S rRNA and housekeeping (atpD, recA and glnII) genes, and DNA relatedness. Three strains in group I were classified as R. giardinii, as they showed high gene sequence similarities (>97 %) and DNA relatedness (64.3-67.5 %) to R. giardinii H152(T). Groups II, III and IV differed from all defined Rhizobium species based upon the consensus of all analyses. As group II contained two strains that originated from two distinct populations, we propose this group as a novel species, Rhizobium herbae sp. nov., with strain CCBAU 83011(T) ( = LMG 25718(T) = HAMBI 3117(T)) as the type strain.

  7. TOLERANCIA A ACIDEZ EN Rhizobium trifolii

    OpenAIRE

    Bueno Castillo, Carmen

    2011-01-01

    La tolerancia a acidez de 29 cepas de Rhizobium trifollii de diverso origen, -fue estudiada en el medio líquido acidificado de Keyser y Munns. Doce de las cepas mostraron crecimiento a pH 4-1, medido como densidad óptica a 600 nm, después de un periodo de latericia. De las cepas rhizobianas de origen español, solo crecieron las, aisladas en suelos ácido de regiones húmedas o de regadía. Dos cepas, la tolerante a acidez USDA 2160 y la sensible a acidez 162—X—103 tenían una producción de polisa...

  8. Phylogenetic diversity of Rhizobium strains nodulating diverse legume species growing in Ethiopia.

    Science.gov (United States)

    Degefu, Tulu; Wolde-meskel, Endalkachew; Frostegård, Åsa

    2013-06-01

    The taxonomic diversity of thirty-seven Rhizobium strains, isolated from nodules of leguminous trees and herbs growing in Ethiopia, was studied using multilocus sequence analyses (MLSA) of six core and two symbiosis-related genes. Phylogenetic analysis based on the 16S rRNA gene grouped them into five clusters related to nine Rhizobium reference species (99-100% sequence similarity). In addition, two test strains occupied their own independent branches on the phylogenetic tree (AC86a2 along with R. tibeticum; 99.1% similarity and AC100b along with R. multihospitium; 99.5% similarity). One strain from Milletia ferruginea was closely related (>99%) to the genus Shinella, further corroborating earlier findings that nitrogen-fixing bacteria are distributed among phylogenetically unrelated taxa. Sequence analyses of five housekeeping genes also separated the strains into five well-supported clusters, three of which grouped with previously studied Ethiopian common bean rhizobia. Three of the five clusters could potentially be described into new species. Based on the nifH genes, most of the test strains from crop legumes were closely related to several strains of Ethiopian common bean rhizobia and other symbionts of bean plants (R. etli and R. gallicum sv. phaseoli). The grouping of the test strains based on the symbiosis-related genes was not in agreement with the housekeeping genes, signifying differences in their evolutionary history. Our earlier studies revealing a large diversity of Mesorhizobium and Ensifer microsymbionts isolated from Ethiopian legumes, together with the results from the present analysis of Rhizobium strains, suggest that this region might be a potential hotspot for rhizobial biodiversity.

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

    Science.gov (United States)

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

    2015-12-01

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

  10. Analysis of synonymous codon usage patterns in the genus Rhizobium.

    Science.gov (United States)

    Wang, Xinxin; Wu, Liang; Zhou, Ping; Zhu, Shengfeng; An, Wei; Chen, Yu; Zhao, Lin

    2013-11-01

    The codon usage patterns of rhizobia have received increasing attention. However, little information is available regarding the conserved features of the codon usage patterns in a typical rhizobial genus. The codon usage patterns of six completely sequenced strains belonging to the genus Rhizobium were analysed as model rhizobia in the present study. The relative neutrality plot showed that selection pressure played a role in codon usage in the genus Rhizobium. Spearman's rank correlation analysis combined with correspondence analysis (COA) showed that the codon adaptation index and the effective number of codons (ENC) had strong correlation with the first axis of the COA, which indicated the important role of gene expression level and the ENC in the codon usage patterns in this genus. The relative synonymous codon usage of Cys codons had the strongest correlation with the second axis of the COA. Accordingly, the usage of Cys codons was another important factor that shaped the codon usage patterns in Rhizobium genomes and was a conserved feature of the genus. Moreover, the comparison of codon usage between highly and lowly expressed genes showed that 20 unique preferred codons were shared among Rhizobium genomes, revealing another conserved feature of the genus. This is the first report of the codon usage patterns in the genus Rhizobium.

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

    National Research Council Canada - National Science Library

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

    2013-01-01

    ...) and 16S rRNA gene sequence analysis. Most isolates corresponded to members of the genus Rhizobium and those not related to species with validly published names were further characterized by recA, atpD, rpoB and nifH gene phylogenies...

  12. Draft Genome Sequence of the Nitrogen-Fixing Rhizobium sullae Type Strain IS123T Focusing on the Key Genes for Symbiosis with its Host Hedysarum coronarium L.

    Directory of Open Access Journals (Sweden)

    Gaurav Sablok

    2017-07-01

    Full Text Available The prominent feature of rhizobia is their molecular dialogue with plant hosts. Such interaction is enabled by the presence of a series of symbiotic genes encoding for the synthesis and export of signals triggering organogenetic and physiological responses in the plant. The genome of the Rhizobium sullae type strain IS123T nodulating the legume Hedysarum coronarium, was sequenced and resulted in 317 scaffolds for a total assembled size of 7,889,576 bp. Its features were compared with those of genomes from rhizobia representing an increasing gradient of taxonomical distance, from a conspecific isolate (Rhizobium sullae WSM1592, to two congeneric cases (Rhizobium leguminosarum bv. viciae and Rhizobium etli and up to different genera within the legume-nodulating taxa. The host plant is of agricultural importance, but, unlike the majority of other domesticated plant species, it is able to survive quite well in the wild. Data showed that that the type strain of R. sullae, isolated from a wild host specimen, is endowed with a richer array of symbiotic genes in comparison to other strains, species or genera of rhizobia that were rescued from domesticated plant ecotypes. The analysis revealed that the bacterium by itself is incapable of surviving in the extreme conditions that its host plant can tolerate. When exposed to drought or alkaline condition, the bacterium depends on its host to survive. Data are consistent with the view of the plant phenotype as the primary factor enabling symbiotic nitrogen fixing bacteria to survive in otherwise limiting environments.

  13. 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.

  14. Rhizobium petrolearium sp. nov., isolated from oil-contaminated soil.

    Science.gov (United States)

    Zhang, Xiaoxia; Li, Baoming; Wang, Haisheng; Sui, Xinhua; Ma, Xiaotong; Hong, Qing; Jiang, Ruibo

    2012-08-01

    Two Gram-negative, aerobic, rod-shaped bacteria, designated strains SL-1(T) and F11, which had the ability to decompose polycyclic aromatic hydrocarbons (PAHs), were isolated from soil samples contaminated by oil. The cells were motile by polar or lateral flagella. According to comparison of 16S rRNA gene sequences, strains SL-1(T) and F11 were identical and showed the greatest degree of similarity (96.8%) to both Rhizobium oryzae Alt505(T) and Rhizobium mesosinicum CCBAU 25010(T); however, only Rhizobium oryzae with SL-1(T) and F11 formed a separate clade. There were low similarities (Rhizobium. The bacteria grew at temperatures of 10-40 °C with an optimum of 30 °C. The pH range for growth was 6.0-10.0 and optimum pH was 7.0-8.0. Growth occurred at NaCl concentrations up to 3.0% (w/v). They were catalase- and oxidase-positive. The main cellular fatty acids were summed feature 8 (18:1ω7c and/or 18:1ω6c) and 16:0. The DNA G+C content was 62.2 mol%. Strain SL-1(T) showed 29 and 0% DNA-DNA relatedness, respectively, with the most related strains R. oryzae Alt505(T) and R. mesosinicum CCBAU 25010(T) according to phylogenic analysis of the 16S rRNA gene. According to physiological and biochemical characteristics and genotypic data obtained in this work, the bacteria represent a novel species of the genus Rhizobium, and the name Rhizobium petrolearium is proposed. The type strain is SL-1(T) ( = ACCC 11238(T) = KCTC 23288(T)) and it could nodulate Medicago sativa in nodulation tests.

  15. Assessment of Qualitative and Quantitative Characters of Two Persian Clover Ecotypes Inoculated by Rhizobium leguminosarum biovartrifoli and Pesudomonas putida Bacteria

    Directory of Open Access Journals (Sweden)

    R Azamei

    2016-02-01

    the powder used for inoculum was 5 gram from every bacterium seed (Containing 108 × 5 bacteria per gram for 100 kg seed. For better adhesion of the bacteria on the surface of seed, water with 20% sugar solution was used. (2 Sampling performed by harvesting 2 meter of every plot and 2 kg of fresh yield was transferred to oven (48 hours with (72 °C to determine dry matter. The crude protein content was determined by multiplying nitrogen content by the correction factor (6.25. At the end of the season a few plants from each plot were selected, and the number of nodules formed on the roots were counted and secondary roots with the highest penetration depth were measured by ruler. Analysis of variance and the means of treatments were performed using SAS software. Average interaction MSTAT- C treatments were performed using the software and the treatments were compared based on Duncan method. Results and Discussion The results showed that the qualitative factors have not been affected by Rhizobium and Pseudomonas bacteria so that the differences between treated plots with control were not significant. The quantitative factors except for depth of root penetration were affected by inoculation with Rhizobium and Pseudomonas bacteria and a significant difference between treated plots and control was obtained. Roberts et al. (3 reported that delay in planting caused plant growth exposure to high temperatures and long days, thus cell walls were stimulated to increase fiber and protein content and consequently digestibility was extremely reduced. The results indicated that inoculation by both bacteria (Rhizobium and Pseudomonas has affected quantitative indicators of growth significantly and increased fresh and dry yield, plant height, leaf/stem ratio and the number of nodes on roots. However the results showed that the qualitative characteristics and root infiltration did not change significantly by inoculation of both bacteria. Plant growth promoting rhizobacteria (PGPR leaded

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

    Science.gov (United States)

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

    2015-01-01

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

  17. Rhizobium-legume symbioses: the crucial role of plant immunity.

    Science.gov (United States)

    Gourion, Benjamin; Berrabah, Fathi; Ratet, Pascal; Stacey, Gary

    2015-03-01

    New research results have significantly revised our understanding of the rhizobium-legume infection process. For example, Nod factors (NFs), previously thought to be absolutely essential for this symbiosis, were shown to be dispensable under particular conditions. Similarly, an NF receptor, previously considered to be solely involved in symbiosis, was shown to function during plant pathogen infections. Indeed, there is a growing realization that plant innate immunity is a crucial component in the establishment and maintenance of symbiosis. We review here the factors involved in the suppression of plant immunity during rhizobium-legume symbiosis, and we attempt to place this information into context with the most recent and sometimes surprising research results.

  18. Fast induction of biosynthetic polysaccharide genes lpxA, lpxE, and rkpI of Rhizobium sp. strain PRF 81 by common bean seed exudates is indicative of a key role in symbiosis.

    Science.gov (United States)

    Oliveira, Luciana Ruano; Rodrigues, Elisete Pains; Marcelino-Guimarães, Francismar Corrêa; Oliveira, André Luiz Martinez; Hungria, Mariangela

    2013-06-01

    Rhizobial surface polysaccharides (SPS) are, together with nodulation (Nod) factors, recognized as key molecules for establishment of rhizobia-legume symbiosis. In Rhizobium tropici, an important nitrogen-fixing symbiont of common bean (Phaseolus vulgaris L.), molecular structures and symbiotic roles of the SPS are poorly understood. In this study, Rhizobium sp. strain PRF 81 genes, belonging to the R. tropici group, were investigated: lpxA and lpxE, involved in biosynthesis and modification of the lipid-A anchor of lipopolysaccharide (LPS), and rkpI, involved in synthesis of a lipid carrier required for production of capsular polysaccharides (KPS). Reverse transcription quantitative PCR (RT-qPCR) analysis revealed, for the first time, that inducers released from common bean seeds strongly stimulated expression of all three SPS genes. When PRF 81 cells were grown for 48 h in the presence of seed exudates, twofold increases (p PRF81 and of the type strain of R. tropici CIAT899(T)clustered with orthologous Rhizobium radiobacter and were more related to R. etli and Rhizobium leguminosarum, while rkpI was closer to the Sinorhizobium sp. group. Upregulation of lpxE, lpxA, and rkpI genes suggests that seed exudates can modulate production of SPS of Rhizobium sp. PRF81, leading to cell wall changes necessary for symbiosis establishment.

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

    Science.gov (United States)

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

    2015-02-01

    Five bacterial strains representing 45 isolates originated from root nodules of the medicinal legume Sophora flavescens were defined as two novel groups in the genus Rhizobium based on their phylogenetic relationships estimated from 16S rRNA genes and the housekeeping genes recA, glnII and atpD. These groups were distantly related to Rhizobium leguminosarum USDA 2370(T) (95.6 % similarity for group I) and Rhizobium phaseoli ATCC 14482(T) (93.4 % similarity for group II) in multilocus sequence analysis. In DNA-DNA hybridization experiments, the reference strains CCBAU 03386(T) (group I) and CCBAU 03470(T) (group II) showed levels of relatedness of 17.9-57.8 and 11.0-42.9 %, respectively, with the type strains of related species. Both strains CCBAU 03386(T) and CCBAU 03470(T) contained ubiquinone 10 (Q-10) as the major respiratory quinone and possessed 16 : 0, 18 : 0, 19 : 0 cyclo ω8c, summed feature 8 and summed feature 2 as major fatty acids, but did not contain 20 : 3 ω6,8,12c. Phenotypic features distinguishing both groups from all closely related species of the genus Rhizobium were found. Therefore, two novel species, Rhizobium sophorae sp. nov. for group I (type strain CCBAU 03386(T) = E5(T) = LMG 27901(T) = HAMBI 3615(T)) and Rhizobium sophoriradicis sp. nov. for group II (type strain CCBAU 03470(T) = C-5-1(T) = LMG 27898(T) = HAMBI 3510(T)), are proposed. Both groups were able to nodulate Phaseolus vulgaris and their hosts of origin (Sophora flavescens) effectively and their nodulation gene nodC was phylogenetically located in the symbiovar phaseoli.

  20. Common links in the structure and cellular localization of Rhizobium chitolipooligosaccharides and general Rhizobium membrane phospholipid and glycolipid components.

    Science.gov (United States)

    Cedergren, R A; Lee, J; Ross, K L; Hollingsworth, R I

    1995-04-04

    Several common links between the structural chemistry of the chitolipooligosaccharides of Rhizobium and the general rhizobial membrane lipid and lipopolysaccharide chemistry of these bacteria have been uncovered. Aspects of common chemistry include sulfation, methylation, and the position and extent of fatty acyl chain unsaturation. We find that bacteria which are known to synthesize sulfated chitolipooligosaccharides (such as Rhizobium meliloti strains and the broad-host-range Rhizobium species strain NGR234) also have sulfated lipopolysaccharides. Their common origins of sulfation have been demonstrated by using mutants which are known to be impaired in sulfating their chitolipooligosaccharides. In such cases, there is a corresponding diminution or complete lack of sulfation of the lipopolysaccharides. The structural diversity of the fatty acids observed in the chitolipooligosaccharides is also observed in the other membrane lipids. For instance, the doubly unsaturated fatty acids which are known to be predominant components of R. meliloti chitolipooligosaccharides were also found in the usual phospholipids and glycolipids. Also, the known functionalization of the chitolipooligosaccharides of R. sp. NGR234 by O- and N-methylation was also reflected in the lipopolysaccharide of this organism. The common structural features of chitolipooligosaccharides and membrane components are consistent with a substantial degree of biosynthetic overlap and a large degree of cellular, spatial overlap between these molecules. The latter aspect is clearly demonstrated here since we show that the chitolipooligosaccharides are, in fact, normal membrane components of Rhizobium. This increases the importance of understanding the role of the bacterial cell surface chemistry in the Rhizobium/legume symbiosis and developing a comprehensive understanding of the highly integrated membrane lipid and glycolipid chemistry of Rhizobium.

  1. A novel capsular polysaccharide from Rhizobium rubi strain DSM 30149.

    Science.gov (United States)

    De Castro, Cristina; Fregolino, Eleonora; Gargiulo, Valentina; Lanzetta, Rosa; Parrilli, Michelangelo

    2008-07-07

    Rhizobium rubi, strain DSM 30149, is a Gram negative phytopathogenic bacterium which produces a linear polysaccharide with the following repeating unit: This new structure was determined by spectroscopical and chemical methods. It presents similar lipophilic features reported for another strain of R. rubi. These contrast with features already known for capsular polysaccharide species from symbiontic members of the Rhizobiaceae family, namely highly anionic polymers.

  2. Molecular markers to study competition and diversity of Rhizobium

    NARCIS (Netherlands)

    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 mi

  3. Towards in vivo imaging of early Rhizobium Nod factor responses

    NARCIS (Netherlands)

    Krogt, van der G.N.M.

    2006-01-01

    The goal in this thesis is to explore the possibility of live imaging of cellular events using fluorescence microscopy in combination with Green Fluorescent Protein (GFP) based reporter constructs in root hairs during theRhizobium-legume interaction. Legumes have the abilit

  4. 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...

  5. 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...

  6. Rhizobium laguerreae sp. nov. nodulates Vicia faba on several continents.

    Science.gov (United States)

    Saïdi, Sabrine; Ramírez-Bahena, Martha-Helena; Santillana, Nery; Zúñiga, Doris; Álvarez-Martínez, Estela; Peix, Alvaro; Mhamdi, Ridha; Velázquez, Encarna

    2014-01-01

    Several fast-growing strains nodulating Vicia faba in Peru, Spain and Tunisia formed a cluster related to Rhizobium leguminosarum. The 16S rRNA gene sequences were identical to that of R. leguminosarum USDA 2370(T), whereas rpoB, recA and atpD gene sequences were phylogenetically distant, with sequence similarities of less than 96 %, 97 % and 94 %, respectively. DNA-DNA hybridization analysis showed a mean relatedness value of 43 % between strain FB206(T) and R. leguminosarum USDA 2370(T). Phenotypic characteristics of the novel strains also differed from those of the closest related species of the genus Rhizobium. Therefore, based on genotypic and phenotypic data obtained in this study, we propose to classify this group of strains nodulating Vicia faba as a novel species of the genus Rhizobium named Rhizobium laguerreae sp. nov. The type strain is FB206(T) ( = LMG 27434(T) = CECT 8280(T)).

  7. Organic Acid Metabolism by Isolated Rhizobium japonicum Bacteroids

    Science.gov (United States)

    Stovall, Iris; Cole, Michael

    1978-01-01

    Rhizobium japonicum bacteroids isolated from soybean (Glycine max L.) nodules oxidized 14C-labeled succinate, pyruvate, and acetate in a manner consistent with operation of the tricarboxylic acid cycle and a partial glyoxylate cycle. Substrate carbon was incorporated into all major cellular components (cell wall + membrane, nucleic acids, and protein). PMID:16660386

  8. Nod factor signal transduction in the Rhizobium-legume symbiosis

    NARCIS (Netherlands)

    Limpens, E.H.M.; Bisseling, T.

    2008-01-01

    The symbiotic interaction between Rhizobium bacteria and most legume plants is initiated by the perception of bacterial signal molecules, the nodulation (Nod) factors, at the root hairs of the plant. This induces responses both in the root hairs, leading to infection by the bacteria, as well as at a

  9. The Rhizobium-pea symbiosis as affected by high temperatures

    NARCIS (Netherlands)

    Frings, J.F.J.

    1976-01-01

    A study has been made concerning the effect of high temperatures on the symbiosis of Rhizobium leguminosarum and pea plants (Pisum sativum). At 30°C, no nodules were found on the roots of plants growing in nutrient solution after inoculation with the appropriate bacteria. This is in contrast to the

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

    NARCIS (Netherlands)

    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

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

    Science.gov (United States)

    Kittiwongwattana, Chokchai; Thawai, Chitti

    2014-07-01

    Bacterial strain L6-16(T) was isolated from Lemna aequinoctialis. Cells were Gram-stain-negative, rod-shaped and motile with monopolar flagella. The phylogenetic analysis of its nearly complete 16S rRNA gene sequence revealed that strain L6-16(T) was a member of the genus Rhizobium. Its closest relative was Rhizobium tarimense PL-41(T) with a 16S rRNA gene sequence similarity value of 98.3%. Sequence similarity analysis of the housekeeping recA and atpD genes showed low levels of sequence similarity (Rhizobium. Strain L6-16(T) was able to grow between pH 5 and 11 (optimum 7.0) and at temperatures ranging from 20 to 41 °C (optimum 30 °C). It tolerated NaCl up to 1 % (w/v) (optimum 0.5%). C18 : 1ω7c and/or C18 :  1ω6c (summed feature 8; 79.5%) were found as predominant cellular fatty acids. The DNA G+C content of strain L6-16(T) was 58.1 mol% (Tm). Based on low levels of DNA-DNA relatedness, strain L6-16(T) was distinct from members of phylogenetically related species including R. tarimense PL-41(T) (38.3 ± 0.8%), Rhizobium rosettiformans W3(T) (6.9 ± 0.4%) and Rhizobium pseudoryzae J3-A127(T) (12.3 ± 0.6 %). Strain L6-16(T) was unable to nodulate the roots of Phaseolus vulgaris, and nodC and nifH genes were not detected. The results obtained from phylogenetic analyses, phenotypic characterization and DNA-DNA hybridization indicated that strain L6-16(T) represents a novel species of the genus Rhizobium, for which the name Rhizobium lemnae sp. nov. is proposed. The type strain is L6-16(T) ( = NBRC 109339(T) = BCC 55143(T)).

  12. Rhizobium paknamense sp. nov., isolated from lesser duckweeds (Lemna aequinoctialis).

    Science.gov (United States)

    Kittiwongwattana, Chokchai; Thawai, Chitti

    2013-10-01

    A Gram-stain-negative, rod-shaped bacterium was isolated and designated strain L6-8(T) during a study of endophytic bacterial communities in lesser duckweed (Lemna aequinoctialis). Cells of strain L6-8(T) were motile with peritrichous flagella. The analysis of the nearly complete 16S rRNA gene sequence indicated that strain L6-8(T) was phylogenetically related to species of the genus Rhizobium. Its closest relatives were Rhizobium borbori DN316(T) (97.6 %), Rhizobium oryzae Alt 505(T) (97.3 %) and Rhizobium pseudoryzae J3-A127(T) (97.0 %). The sequence similarity analysis of housekeeping genes recA, glnII, atpD and gyrB showed low levels of sequence similarity (Rhizobium with validly published names. The pH range for growth was 4.0-9.0 (optimum 6.0-7.0), and the temperature range for growth was 20-45 °C (optimum 30 °C). Strain L6-8(T) tolerated NaCl up to 2 % (w/v) (optimum 1 % NaCl). The predominant components of cellular fatty acids were C19 : 0 cyclo ω8c (31.32 %), summed feature 8 (C18 : 1ω7c and/or C18 : 1ω6c; 25.39 %) and C16 : 0 (12.03 %). The DNA G+C content of strain L6-8(T) was 60.4 mol% (Tm). nodC and nifH were not amplified in strain L6-8(T). DNA-DNA relatedness between strain L6-8(T) and R. borbori DN316(T), R. oryzae Alt505(T) and R. pseudoryzae J3-A127(T) was between 11.2 and 18.3 %. Based on the sequence similarity analyses, phenotypic, biochemical and physiological characteristics and DNA-DNA hybridization, strain L6-8(T) could be readily distinguished from its closest relatives and represents a novel species of the genus Rhizobium, for which the name Rhizobium paknamense sp. nov. is proposed. The type strain is L6-8(T) ( = NBRC 109338(T) = BCC 55142(T)).

  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 %.

  14. Rhizobium pseudoryzae sp. nov., isolated from the rhizosphere of rice.

    Science.gov (United States)

    Zhang, Xiaoxia; Sun, Lei; Ma, Xiaotong; Sui, Xin Hua; Jiang, Ruibo

    2011-10-01

    A Gram-stain-negative, aerobic, rod-shaped bacterium, designated strain J3-A127(T), was isolated from the roots of fresh rice plants (Oryza sativa). Cells were non-motile and no flagellum was detected. Comparison of 16S rRNA gene sequences indicated that the strain was phylogenetically related to species of the genus Rhizobium, with closest similarity to Rhizobium oryzae Alt 505(T) (96.4 %). The low levels of 16S rRNA gene sequence similarity (Rhizobium also indicated that it represented a separate species. The temperature range for growth was 10-40 °C (optimum around 28 °C) and the pH range was 6.0-11.0 (optimum pH 7.0-8.0). Strain J3-A127(T) tolerated NaCl concentrations up to 5.0 % (w/v). The strain was catalase- and oxidase-positive. The main cellular fatty acids were summed feature 8 (C(18 : 1)ω7c and/or C(18 : 1)ω6; 46.7 %). The DNA G+C content of strain J3-A127(T) was 59.5 mol%. Strain J3-A127(T) did not form any nodules on four different legumes and the nodD and nifH genes were not detected by PCR. According to physiological and biochemical characteristics and genotypic data, strain J3-A127(T) is considered to represent a novel species of the genus Rhizobium, for which the name Rhizobium pseudoryzae sp. nov. is proposed. The type strain is J3-A127(T) ( = ACCC 10380(T) = KCTC 23294(T)).

  15. Rhizobium rhizoryzae sp. nov., isolated from rice roots.

    Science.gov (United States)

    Zhang, Xiao-Xia; Tang, Xue; Sheirdil, Rizwan Ali; Sun, Lei; Ma, Xiao-Tong

    2014-04-01

    Two strains (J3-AN59(T) and J3-N84) of Gram-stain-negative, aerobic and rod-shaped bacteria were isolated from the roots of fresh rice plants. The 16S rRNA gene sequence similarity results showed that the similarity between strains J3-AN59(T) and J3-N84 was 100 %. Both strains were phylogenetically related to members of the genus Rhizobium, and they were most closely related to Rhizobium tarimense ACCC 06128(T) (97.43 %). Similarities in the sequences of housekeeping genes between strains J3-AN59(T) and J3-N84 and those of recognized species of the genus Rhizobium were less than 90 %. The polar lipid profiles of both strains were predominantly composed of phosphatidylglycerol, diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylcholine and an unknown aminophospholipid. The major cellular fatty acids were summed feature 8 (C18 : 1ω7c and/or C18 : 1ω6c) and C16 : 0. The DNA G+C contents of J3-AN59(T) and J3-N84 were 55.7 and 57.1 mol%, respectively. The DNA-DNA relatedness value between J3-AN59(T) and J3-N84 was 89 %, and strain J3-AN59(T) showed 9 % DNA-DNA relatedness to R. tarimense ACCC 06128(T), the most closely related strain. Based on this evidence, we found that J3-AN59(T) and J3-N84 represent a novel species in the genus Rhizobium and we propose the name Rhizobium rhizoryzae sp. nov. The type strain is J3-AN59(T) ( = ACCC 05916(T) = KCTC 23652(T)).

  16. 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 : 1ω7c 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)).

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

    Energy Technology Data Exchange (ETDEWEB)

    Hollingsworth, R.I.

    1991-12-31

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

  18. RepA and RepB exert plasmid incompatibility repressing the transcription of the repABC operon.

    Science.gov (United States)

    Pérez-Oseguera, Angeles; Cevallos, Miguel A

    2013-11-01

    Rhizobium etli CFN42 has a multipartite genome composed of one chromosome and six large plasmids with low copy numbers, all belonging to the repABC plasmid family. All elements essential for replication and segregation of these plasmids are encoded within the repABC operon. RepA and RepB direct plasmid segregation and are involved in the transcriptional regulation of the operon, and RepC is the initiator protein of the plasmid. Here we show that in addition to RepA (repressor) and RepB (corepressor), full transcriptional repression of the operon located in the symbiotic plasmid (pRetCFN42d) of this strain requires parS, the centromere-like sequence, and the operator sequence. However, the co-expression of RepA and RepB is sufficient to induce the displacement of the parental plasmid. RepA is a Walker-type ATPase that self associates in vivo and in vitro and binds specifically to the operator region in its RepA-ADP form. In contrast, RepA-ATP is capable of binding to non-specific DNA. RepA and RepB form high molecular weight DNA-protein complexes in the presence of ATP and ADP. RepA carrying ATP-pocket motif mutations induce full repression of the repABC operon without the participation of RepB and parS. These mutants specifically bind the operator sequence in their ATP or ADP bound forms. In addition, their expression in trans exerts plasmid incompatibility against the parental plasmid. RepA and RepB expressed in trans induce plasmid incompatibility because of their ability to repress the repABC operon and not only by their capacity to distort the plasmid segregation process.

  19. 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 arabin......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...

  20. Impact of heavy metals on an arctic rhizobium

    Energy Technology Data Exchange (ETDEWEB)

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

    1991-03-01

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

  1. Role of Symbiotic Auxotrophy in the Rhizobium-Legume Symbioses

    OpenAIRE

    Jurgen Prell; Alexandre Bourdès; Shalini Kumar; Emma Lodwig; Arthur Hosie; Seonag Kinghorn; James White; Philip Poole

    2010-01-01

    Background Rhizobium leguminosarum bv. viciae mutants unable to transport branched-chain amino acids via the two main amino acid ABC transport complexes AapJQMP and BraDEFGC produce a nitrogen starvation phenotype when inoculated on pea (Pisum sativum) plants [1], [2]. Bacteroids in indeterminate pea nodules have reduced abundance and a lower chromosome number. They reduce transcription of pathways for branched-chain amino acid biosynthesis and become dependent on their provision by the host....

  2. 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...

  3. 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) ω7c (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.

  4. 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 : 1ω7c and/or 18 : 1ω6c; 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

  5. Root Exudates of Various Host Plants of Rhizobium leguminosarum Contain Different Sets of Inducers of Rhizobium Nodulation Genes.

    Science.gov (United States)

    Zaat, S A; Wijffelman, C A; Mulders, I H; van Brussel, A A; Lugtenberg, B J

    1988-04-01

    Rhizobium promoters involved in the formation of root nodules on leguminous plants are activated by flavonoids in plant root exudate. A series of Rhizobium strains which all contain the inducible Rhizobium leguminosarum nodA promoter fused to the Escherichia coli lacZ gene, and which differ only in the source of the regulatory nodD gene, were recently used to show that the regulatory nodD gene determines which flavonoids are able to activate the nodA promoter (HP Spaink, CA Wijffelman, E Pees, RJH Okker, BJJ Lugtenberg 1987 Nature 328: 337-340). Since these strains therefore are able to discriminate between various flavonoids, they were used to determine whether or not plants that are nodulated by R. leguminosarum produce different inducers. After chromatographic separation of root exudate constituents from Vicia sativa L. subsp. nigra (L.), V. hirsuta (L.) S.F. Gray, Pisum sativum L. cv Rondo, and Trifolium subterraneum L., the fractions were tested with a set of strains containing a nodD gene of R. leguminosarum, R. trifolii, or Rhizobium meliloti, respectively. It appeared that the source of nodD determined whether, and to what extent, the R. leguminosarum nodA promoter was induced. Lack of induction could not be attributed to the presence of inhibitors. Most of the inducers were able to activate the nodA promoter in the presence of one particular nodD gene only. The inducers that were active in the presence of the R. leguminosarum nodD gene were different in each root exudate.

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

    Science.gov (United States)

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

    2016-04-01

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

  7. 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...

  8. Energy supply for dinitrogen fixation by Azotobacter vinelandii and by bacteroids of Rhizobium leguminosarum

    NARCIS (Netherlands)

    Laane, N.C.M.

    1980-01-01

    The central issue of this thesis is how obligate aerobes, such as Rhizobium leguminosarum bacteroids and Azotobacter vinelandii, generate and regulate the energy supply (in the form of ATP and reducing equivalents) for nitrogenase.In an effective Rhizobium -legume symbiosis, the actual reduction of

  9. 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.

  10. 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-...

  11. LysM-Type Mycorrhizal Receptor Recruited for Rhizobium Symbiosis in Nonlegume Parasponia

    NARCIS (Netherlands)

    Camp, Op den R.H.M.; Streng, A.J.; Mita, De S.; Cao, Q.; Polone, E.; Liu, W.; Ammiraju, J.S.S.; Kudrna, D.; Wing, R.; Untergasser, A.; Bisseling, T.; Geurts, R.

    2011-01-01

    Rhizobium root nodule symbiosis is generally considered to be unique for legumes. However, there is one exception and that is Parasponia. In this nonlegume, the rhizobial nodule symbiosis evolved independently and is, like in legumes, induced by rhizobium Nod factors. We used Parasponia to identify

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

    NARCIS (Netherlands)

    Schetgens, T.M.P.

    1986-01-01

    Bacteria of the genera Rhizobium and Bradyrhizobium are unique in their quality to form nitrogen-fixing root nodules in symbiosis with leguminous plants. In fast-growing Rhizobium bacteria the genes involved in host recognition and nodule development ( nod ) and in nitrog

  13. Studies on the expression of plasmid-borne genes in the endosymbiotic state of Rhizobium leguminosarum

    NARCIS (Netherlands)

    Krol, A.J.M.

    1982-01-01

    The subject matter of the research reported in this thesis is the role of plasmid-borne genes of Rhizobium in symbiosis and nitrogen fixation. Plasmid DNA was isolated from Rhizobium leguminosarum strain PRE and the expression of plasmid DNA in nitrogen fixing nodules was investigated by hybridizati

  14. Co-option of pre-existing pathways during Rhizobium-legume symbiosis evolution

    NARCIS (Netherlands)

    Lillo, A.

    2012-01-01

    Fixed nitrogen is one of the most limiting factors for plant growth. One of the most important nitrogen-fixing systems is the rhizobium root nodule symbiosis. In this Thesis I have studied the legume-rhizobium symbiosis, starting from the idea that part of pre-existing signalling pathways have been

  15. Nonlegume Parasponia andersonii deploys a broad rhizobium host range strategy resulting in largely variable symbiotic effectiveness

    NARCIS (Netherlands)

    Camp, op den R.H.M.; Polone, E.; Fedorova, E.; Roelofsen, W.; Squartini, A.; Camp, op den H.J.M.; Bisseling, T.; Geurts, R.

    2012-01-01

    The non-legume genus Parasponia has evolved the rhizobium symbiosis independent from legumes and has done so only recently. We aim to study the promiscuity of such newly evolved symbiotic engagement and determine the symbiotic effectiveness of infecting rhizobium species. It was found that Parasponi

  16. Genetic constraints that determine rhizobium-root nodule formation in Parasponia andersonii

    NARCIS (Netherlands)

    Seifi Kalhor, M.

    2016-01-01

    Bacteria of the genus Rhizobium play a very important role in agriculture by inducing nitrogen-fixing nodules on the roots of legumes. Root nodule symbiosis enables nitrogen‐fixing bacteria (Rhizobium) to convert atmospheric nitrogen into a form that is directly available for plant growth.

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

    DEFF Research Database (Denmark)

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

    1986-01-01

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

  18. Genetic constraints that determine rhizobium-root nodule formation in Parasponia andersonii

    NARCIS (Netherlands)

    Seifi Kalhor, M.

    2016-01-01

    Bacteria of the genus Rhizobium play a very important role in agriculture by inducing nitrogen-fixing nodules on the roots of legumes. Root nodule symbiosis enables nitrogen‐fixing bacteria (Rhizobium) to convert atmospheric nitrogen into a form that is directly available for plant growth.

  19. Soil moisture deficit selects for desiccation tolerant Rhizobium leguminosarum bv. trifolii

    NARCIS (Netherlands)

    Ham, van Robert; O'Callaghan, Maureen; Geurts, Rene; Ridgway, Hayley J.; Ballard, Ross; Noble, Alasdair; Macara, Gregor; Wakelin, Steven A.

    2016-01-01

    Tolerance to desiccation is a highly desirable attribute for Rhizobium spp., which are widely used as symbionts of pasture legumes. Poor survival of Rhizobium spp. is of particular concern during the commercial formulation and seed application phase, but also when sown into dry fields and during sap

  20. Toxicity testing of heavy metals with the Rhizobium-legume symbiosis: High sensitivity to cadmium and arsenic compounds.

    Science.gov (United States)

    Neumann, H; Bode-Kirchhoff, A; Madeheim, A; Wetzel, A

    1998-01-01

    Legume root nodules are the site of biological nitrogen fixation in the Rhizobium-legume symbiosis. Nodules are structures unique to this symbiosis and they are morphologically as well as physiologically distinct from other plant organs. Organic substances affecting the macro- or microsymbionts vitality, such as PAHs (WETZEL: et al., 1991), reduce nodulation even before visible damage to the plant can be detected. We present data that the formation of nodules (nodulation) may also serve for ecotoxicological evaluation of heavy metals in different binding states. Tests were performed in petri dishes with alfalfa (lucerne) seedlings inoculated with Rhizobium meliloti. Cultivation took place in growth cabinets with carefully standardized and documented growth conditions. Data from stressed plants was recorded after 14 days of cultivation on contaminated substrate. A dose responsive decrease in nodulation was found after application of cadmium acetate, cadmium iodide, cadmium chloride, sodium salts of arsenate and arsenite, arsenic pentoxide, and lead nitrate, whereas lead acetate showed no effect up to a concentration of 3 microM. The dose response curves were used to calculate EC10, EC50 and EC90 values. EC50 values for cadmium compounds range from 1.5 to 9.5 pM. Testing different arsenic compounds results in EC50 from 2.6 to 20.1 microM. EC50 of lead nitrate is 2.2 microM. The sensitivity, reproducibility and reliability of this test system is discussed compared to established biotests.

  1. A common genomic framework for a diverse assembly of plasmids in the symbiotic nitrogen fixing bacteria.

    Directory of Open Access Journals (Sweden)

    Lisa C Crossman

    Full Text Available This work centres on the genomic comparisons of two closely-related nitrogen-fixing symbiotic bacteria, Rhizobium leguminosarum biovar viciae 3841 and Rhizobium etli CFN42. These strains maintain a stable genomic core that is also common to other rhizobia species plus a very variable and significant accessory component. The chromosomes are highly syntenic, whereas plasmids are related by fewer syntenic blocks and have mosaic structures. The pairs of plasmids p42f-pRL12, p42e-pRL11 and p42b-pRL9 as well large parts of p42c with pRL10 are shown to be similar, whereas the symbiotic plasmids (p42d and pRL10 are structurally unrelated and seem to follow distinct evolutionary paths. Even though purifying selection is acting on the whole genome, the accessory component is evolving more rapidly. This component is constituted largely for proteins for transport of diverse metabolites and elements of external origin. The present analysis allows us to conclude that a heterogeneous and quickly diversifying group of plasmids co-exists in a common genomic framework.

  2. 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...

  3. Viability of Rhizobium bacteroids isolated from soybean nodule protoplasts.

    Science.gov (United States)

    Gresshoff, P M; Rolfe, B G

    1978-01-01

    Bacteriods isolated from protoplasts taken from Rhizobium japonicum induced root nodule of Glycine max L. showed complete viability when plated onto a conventional rhizobial growth medium supplemented with 0.2 M Mannitol. The same medium but without extra mannitol resulted in the absence of colony formation. The protoplast isolation method eliminated the possibility of contaminant bacteria from infection threads to be scored. The redifferentiated bacteroid clones have the same genetical characteristics as the orginal inoculum strain. This and other recent findings of bacteroid viability are discussed in the light of the existing belief that bacteroids are non-viable.

  4. Effect of Rhizobium Inoculation on Phosphorus Uptake, Yield and Quality of Soybean Plants

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    [Objective] This study aimed to investigate the effect of inoculation with various rhizobium strains on growth status, phosphorus uptake, yield and quality of soybean plants. [Method] Using Dongnong 42 and Dongnong 46 as experimental soybeans, four treatments were designed, including non-inoculated CK group and three treatment groups inoculated respectively with rhizobium strains R2, R, and Rs, to analysis the effects of rhizobium inoculation on growth status, phosphorus uptake, yield and quality of soybean plants. [Result] Inoculation with different rhizobium strains could significantly increase the biomass and phosphorus content of the roots and shoots of Dongnong 42, to be specific, rhizobium strain R2 showed the best ef- fect, followed by Rs, and those of roots were improved greater than the shoots; in- oculation with rhizobium could significantly increase the yield of Dongnong 42, and R5 showed the best effect, but the yield of Dongnong 46 was decreased; after in- oculated with rhizobium, the protein content and fat content of soybean were signifi- cantly increased, and R2 showed the best effect, but the effects on different varieties varied, to be specific, the protein content of Dongnong 42 was significantly in- creased, while the fat content of Dongnong 46 was significantly increased; different rhizobium strains inoculated to different soybean varieties showed different effects. Inoculation with suitable rhizobium can improve plant growth characteristics, promote phosphorus uptake of plants, increase soybean yield, and effectively improve soy- bean quality. [Conclusion] This study provides theoretical basis for solving the prob- lem of soil phosphorus deficiency, increasing soybean yield and improving soybean quality in the future.

  5. Rhizobium pakistanensis sp. nov., isolated from groundnut (Arachis hypogaea) nodules grown in rainfed Pothwar, Pakistan.

    Science.gov (United States)

    Khalid, Rabia; Zhang, Yu Jing; Ali, Safdar; Sui, Xin Hua; Zhang, Xiao Xia; Amara, Ummay; Chen, Wen Xin; Hayat, Rifat

    2015-01-01

    A Gram-negative, white, non-motile, rod shaped bacterial strain BN-19(T) was isolated from a root nodule of groundnut (Arachis hypogaea) in Pakistan. Phylogenetic analysis based on 16S rRNA gene sequence revealed that strain BN-19(T) formed a subclade in the genus Rhizobium together with Rhizobium alkalisoli CCBAU 01393(T), Rhizobium vignae CCBAU 05176(T), Rhizobium huautlense SO2(T) and Rhizobium tarimense PL-41(T) with sequence similarities of 97.5, 97.3, 97.2 and 97.1 % respectively. Sequence analysis of housekeeping genes atpD, glnII and recA (with sequence similarities of ≤92 %) confirmed the unique position of BN-19(T) in the genus Rhizobium. DNA-DNA relatedness between the strain BN-19(T) and R. alkalisoli CCBAU 01393(T), R. vignae CCBAU 05176(T), R. huautlense SO2(T) and R. tarimense PL-41(T) were 20.6, 22.5, 15.9 and 20.5 % respectively, further confirming that BN-19(T) represents a novel species in the genus Rhizobium. The DNA G + C content was 60.1 mol%. The dominant fatty acids of strain BN-19(T) were C19:0 cyclo ω8c, summed feature 2 (C14:0 3OH and/or C16:1 iso I) and summed feature 8 (C18:1 ω7c). Some phenotypic features also differentiate the strain BN-19(T) from the related species. On the basis of these results, strain BN-19(T) is considered to represent a novel species in the genus Rhizobium, for which the name Rhizobium pakistanensis sp. nov. is proposed. The type strain is BN-19(T) (=LMG 27895(T) = CCBAU 101086(T)).

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

    Directory of Open Access Journals (Sweden)

    Ni Made Widyasari

    2015-02-01

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

  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. Entrapment of Rhizobium sp. by fluidized bed technique using polymers as coating materials

    Directory of Open Access Journals (Sweden)

    Diego Rivera

    2016-04-01

    Full Text Available The spray-drying technique was applied for the development of three solid formulations of Rhizobium. Sodium alginate and hydroxypropyl methylcellulose (HPMC with concentrations of 0.5 % were used as polymers. Results showed that none of the solid formulations had negative effects in vitro on the growth-promoting capacities of Rhizobium sp. G58 (p < 0.05. PCA´s first three components explained 84.5 % of the total variance. This analysis concluded that the solid formulation had not negative effects on the biological nitrogen fixation activity in vitro or on the process of nodulation in greenhouse experiments. Symbiosis between Rhizobium and the plant was effective, which suggested that, under controlled conditions, the coating process with the polymers had allowed a controlled release of the bacteria and a proper transfer of Rhizobium sp. from the microparticles to the root of the plant.

  9. Rhizobium favelukesii sp. nov., isolated from the root nodules of alfalfa (Medicago sativa L).

    Science.gov (United States)

    Torres Tejerizo, Gonzalo; Rogel, Marco Antonio; Ormeño-Orrillo, Ernesto; Althabegoiti, María Julia; Nilsson, Juliet Fernanda; Niehaus, Karsten; Schlüter, Andreas; Pühler, Alfred; Del Papa, María Florencia; Lagares, Antonio; Martínez-Romero, Esperanza; Pistorio, Mariano

    2016-11-01

    Strains LPU83T and Or191 of the genus Rhizobium were isolated from the root nodules of alfalfa, grown in acid soils from Argentina and the USA. These two strains, which shared the same plasmid pattern, lipopolysaccharide profile, insertion-sequence fingerprint, 16S rRNA gene sequence and PCR-fingerprinting pattern, were different from reference strains representing species of the genus Rhizobium with validly published names. On the basis of previously reported data and from new DNA-DNA hybridization results, phenotypic characterization and phylogenetic analyses, strains LPU83T and Or191 can be considered to be representatives of a novel species of the genus Rhizobium, for which the name Rhizobium favelukesii sp. nov. is proposed. The type strain of this species is LPU83T (=CECT 9014T=LMG 29160T), for which an improved draft-genome sequence is available.

  10. Complete Genome Sequences of Three Rhizobium gallicum Symbionts Associated with Common Bean (Phaseolus vulgaris)

    Science.gov (United States)

    Bustos, Patricia; Santamaría, Rosa Isela; Pérez-Carrascal, Olga María; Acosta, José Luis; Lozano, Luis; Juárez, Soledad; Martínez-Romero, Esperanza; Cevallos, Miguel Ángel; Romero, David; Dávila, Guillermo; Vinuesa, Pablo; Miranda, Fabiola; Ormeño, Ernesto

    2017-01-01

    ABSTRACT The whole-genome sequences of three strains of Rhizobium gallicum reported here support the concept that the distinct nodulation host ranges displayed by the symbiovars gallicum and phaseoli can be largely explained by different symbiotic plasmids. PMID:28302777

  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. Molecular characterization of Tn5-induced symbiotic (Fix-) mutants of Rhizobium meliloti.

    OpenAIRE

    Zimmerman, J L; Szeto, W W; Ausubel, F M

    1983-01-01

    To investigate the expression of specific symbiotic genes during the development of nitrogen-fixing root nodules, we conducted a systematic analysis of nodule-specific proteins and RNAs produced after the inoculation of alfalfa roots with a series of Rhizobium meliloti mutants generated by site-directed transposon Tn5 mutagenesis. The mutagenized region of the Rhizobium genome covered approximately 10 kilobases and included the region encoding the nitrogenase polypeptides. All mutant strains ...

  13. Permanent draft genome of the malachite-green-tolerant bacterium Rhizobium sp. MGL06.

    Science.gov (United States)

    Liu, Yang; Wang, Runping; Zeng, Runying

    2014-12-01

    Rhizobium sp. MGL06, the first Rhizobium isolate from a marine environment, is a malachite-green-tolerant bacterium with a broader salinity tolerance (range: 0.5% to 9%) than other rhizobia. This study sequences and annotates the draft genome sequence of this strain. Genome sequence information provides a basis for analyzing the malachite green tolerance, broad salinity adaptation, nitrogen fixation properties, and taxonomic classification of the isolate.

  14. Genome sequence of the acid-tolerant strain Rhizobium sp. LPU83.

    Science.gov (United States)

    Wibberg, Daniel; Tejerizo, Gonzalo Torres; Del Papa, María Florencia; Martini, Carla; Pühler, Alfred; Lagares, Antonio; Schlüter, Andreas; Pistorio, Mariano

    2014-04-20

    Rhizobia are important members of the soil microbiome since they enter into nitrogen-fixing symbiosis with different legume host plants. Rhizobium sp. LPU83 is an acid-tolerant Rhizobium strain featuring a broad-host-range. However, it is ineffective in nitrogen fixation. Here, the improved draft genome sequence of this strain is reported. Genome sequence information provides the basis for analysis of its acid tolerance, symbiotic properties and taxonomic classification.

  15. Rhizobium helanshanense sp. nov., a bacterium that nodulates Sphaerophysa salsula (Pall.) DC. in China.

    Science.gov (United States)

    Qin, Wei; Deng, Zhen Shan; Xu, Lin; Wang, Na Na; Wei, Ge Hong

    2012-05-01

    Studying rhizobia in the root nodules of Sphaerophysa salsula (Pall.) DC in the northwest of China, we obtained five strains classified as genus Rhizobium on the basis of their 16S rRNA gene sequences. The sequence similarity of strain CCNWQTX14(T) with the most related species was 99.0%. Further phylogenetic analysis of housekeeping genes (recA and atpD) suggested the five strains comprised a novel lineage within Rhizobium. The nifH and nodD gene sequences of CCNWQTX14(T) were phylogenetically closely related with those of Sinorhizobium kummerowiae and R. sphaerophysae, respectively. The five strains isolated from different places were also distinct from related Rhizobium species using ERIC fingerprint profiles. The DNA-DNA hybridization value was 41.8% between CCNWQTX14(T) and Rhizobium sphaerophysae CCNWGS0238(T). Our novel strains were only able to form effective nodules on its original host Sphaerophysa salsula. Our data showed that the five Rhizobium strains formed a unique genomic species, for which a novel species Rhizobium helanshanense sp. nov. is proposed. The type strain is CCNWQTX14(T) (=ACCC 16237(T) =HAMBI 3083(T)).

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

    Directory of Open Access Journals (Sweden)

    Eny Fuskhah

    2014-04-01

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

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

    Science.gov (United States)

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

    2011-11-01

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

  18. Rhizobium vignae sp. nov., a symbiotic bacterium isolated from multiple legume species.

    Science.gov (United States)

    Ren, Da Wei; Chen, Wen Feng; Sui, Xin Hua; Wang, En Tao; Chen, Wen Xin

    2011-03-01

    A group of rhizobial strains isolated from nodules of multiple legume species grown in different geographical regions of China had identical 16S rRNA genes. Phylogenetic analysis based on the 16S rRNA gene sequences showed that the novel strains formed a subclade in the genus Rhizobium together with Rhizobium galegae, Rhizobium huautlense and Rhizobium alkalisoli, with 99.8  % gene sequence similarity between the strains. The DNA-DNA relatedness values between the representative strain CCBAU 05176(T) and R. galegae ATCC 43677(T), R. huautlense S02(T) and R. alkalisoli CCBAU 01393(T) were 22.6  %, 8.9  % and 15.9  %, respectively. The novel strains were distinguished from recognized species of the genus Rhizobium by using a polyphasic approach, including PCR-based restriction fragment length polymorphism analysis (RFLP) of the 16S-23S intergenic spacer (IGS), phenotypic and physiological tests, sequence comparisons of housekeeping genes and cellular fatty acid profiles. Therefore, it is suggested that this group of strains represents a novel species for which the name Rhizobium vignae sp. nov. is proposed. The type strain is CCBAU 05176(T) (=HAMBI 3039(T)=LMG 25447(T)).

  19. Rhizobium tubonense sp. nov., isolated from root nodules of Oxytropis glabra.

    Science.gov (United States)

    Zhang, Rong Juan; Hou, Bao Chao; Wang, En Tao; Li, Ying; Zhang, Xiao Xia; Chen, Wen Xin

    2011-03-01

    Four rhizobial strains, designated CCBAU 85046(T), CCBAU 85051, CCBAU 85048 and CCBAU 85049, isolated from root nodules of Oxytropis glabra grown in Tibet, China, were previously defined, using amplified 16S rRNA gene restriction analysis, as a novel group within the genus Rhizobium. To clarify their taxonomic position, these strains were further analysed and compared with reference strains of related bacteria using a polyphasic approach. The 16S rRNA gene analysis showed that the four isolates formed a distinct phylogenetic lineage in the genus Rhizobium. The isolates showed highest sequence similarity (97.8  %) to Rhizobium indigoferae CCBAU 71042(T). Phenotypic and physiological tests, DNA-DNA hybridization, phylogenetic analyses of housekeeping genes recA, atpD and glnII and fatty acid profiles also indicated that these four strains constitute a novel group distinct from recognized species of the genus Rhizobium. Based on this evidence, strains CCBAU 85046(T), CCBAU 85051, CCBAU 85048 and CCBAU 85049 represent a novel species in the genus Rhizobium, for which the name Rhizobium tubonense sp. nov. is proposed. The type strain is CCBAU 85046(T) (=LMG 25225(T) =HAMBI 3066(T)) and its DNA G+C content is 59.52 % (T(m)). Strain CCBAU 85046(T) could form effective nodules on plant species Vigna unguiculata and Medicago sativa but not on its host of origin Oxytropis glabra.

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

    Directory of Open Access Journals (Sweden)

    Eny Fuskhah

    2014-04-01

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

  1. High lipid productivity of an Ankistrodesmus-Rhizobium artificial consortium.

    Science.gov (United States)

    Do Nascimento, Mauro; Dublan, Maria de los Angeles; Ortiz-Marquez, Juan Cesar Federico; Curatti, Leonardo

    2013-10-01

    Microalgae have great potential as alternative productive platforms for sustainable production of bioenergy, food, feed and other commodities. Process optimization to realize the claimed potential often comprises strains selection and improvement and also developing of more efficient cultivation, harvesting and downstream processing technology. In this work we show that inoculation with the bacterium Rhizobium strain 10II resulted in increments of up to 30% in chlorophyll, biomass and lipids accumulation of the oleaginous microalgae Ankistrodesmus sp. strain SP2-15. Inoculated cultures have reached a high lipid productivity of up to 112 mg L(-1) d(-1) after optimization. The resulting biomass presented significant levels of Ω3 fatty acids including stearidonic acid, suggesting potential as an alternative land-based source of essential fatty acids.

  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. 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...

  4. Role of symbiotic auxotrophy in the Rhizobium-legume symbioses.

    Directory of Open Access Journals (Sweden)

    Jurgen Prell

    Full Text Available Rhizobium leguminosarum bv. viciae mutants unable to transport branched-chain amino acids via the two main amino acid ABC transport complexes AapJQMP and BraDEFGC produce a nitrogen starvation phenotype when inoculated on pea (Pisum sativum plants [1], [2]. Bacteroids in indeterminate pea nodules have reduced abundance and a lower chromosome number. They reduce transcription of pathways for branched-chain amino acid biosynthesis and become dependent on their provision by the host. This has been called "symbiotic auxotrophy".A region important in solute specificity was identified in AapQ and changing P144D in this region reduced branched-chain amino acid transport to a very low rate. Strains carrying P144D were still fully effective for N(2 fixation on peas demonstrating that a low rate of branched amino acid transport in R. leguminosarum bv. viciae supports wild-type rates of nitrogen fixation. The importance of branched-chain amino acid transport was then examined in other legume-Rhizobium symbioses. An aap bra mutant of R. leguminosarum bv. phaseoli also showed nitrogen starvation symptoms when inoculated on French bean (Phaseolus vulgaris, a plant producing determinate nodules. The phenotype is different from that observed on pea and is accompanied by reduced nodule numbers and nitrogen fixation per nodule. However, an aap bra double mutant of Sinorhizobium meliloti 2011 showed no phenotype on alfalfa (Medicago sativa.Symbiotic auxotrophy occurs in both determinate pea and indeterminate bean nodules demonstrating its importance for bacteroid formation and nodule function in legumes with different developmental programmes. However, only small quantities of branched chain amino acids are needed and symbiotic auxotrophy did not occur in the Sinorhizobium meliloti-alfalfa symbiosis under the conditions measured. The contrasting symbiotic phenotypes of aap bra mutants inoculated on different legumes probably reflects altered timing of amino acid

  5. Rhizobium halophytocola sp. nov., isolated from the root of a coastal dune plant.

    Science.gov (United States)

    Bibi, Fehmida; Chung, Eu Jin; Khan, Ajmal; Jeon, Che Ok; Chung, Young Ryun

    2012-08-01

    During a study of endophytic bacteria from coastal dune plants, a bacterial strain, designated YC6881(T), was isolated from the root of Rosa rugosa collected from the coastal dune areas of Namhae Island, Korea. The bacterium was found to be Gram-staining-negative, motile, halophilic and heterotrophic with a single polar flagellum. Strain YC6881(T) grew at temperatures of 4-37 °C (optimum, 28-32 °C), at pH 6.0-9.0 (optimum, pH 7.0-8.0), and at NaCl concentrations in the range of 0-7.5% (w/v) (optimum, 4-5% NaCl). Strain YC6881(T) was catalase- and oxidase-positive and negative for nitrate reduction. According to phylogenetic analysis using 16S rRNA gene sequences, strain YC6881(T) belonged to the genus Rhizobium and showed the highest 16S rRNA gene sequence similarity of 96.9% to Rhizobium rosettiformans, followed by Rhizobium borbori (96.3%), Rhizobium radiobacter (96.1%), Rhizobium daejeonense (95.9%), Rhizobium larrymoorei (95.6%) and Rhizobium giardinii (95.4%). Phylogenetic analysis of strain YC6881(T) by recA, atpD, glnII and 16S-23S intergenic spacer (IGS) sequences all confirmed the phylogenetic arrangements obtained by using 16S rRNA gene sequences. Cross-nodulation tests showed that strain YC6881(T) was a symbiotic bacterium that nodulated Vigna unguiculata and Pisum sativum. The major components of the cellular fatty acids were C(18:1)ω7c (53.7%), C(19:0) cyclo ω8c (12.6%) and C(12:0) (8.1%). The DNA G+C content was 52.8 mol%. Phenotypic and physiological tests with respect to carbon source utilization, antibiotic resistance, growth conditions, phylogenetic analyses of housekeeping genes recA, atpD and glnII, and fatty acid composition could be used to discriminate strain YC6881(T) from other species of the genus Rhizobium in the same sublineage. Based on the results obtained in this study, strain YC6881(T) is considered to represent a novel species of the genus Rhizobium, for which the name Rhizobium halophytocola sp. nov. is proposed. The type

  6. Studi Pendahuluan Isolasi Bakteri Rhizobium Dari Bintil Akar Tanaman Putri Malu ( Mimosa pudica. L) Serta Pemanfaatannya Sebagai Pupuk Hayati (Biofertilizer)Daengan Menggunakan Bentonit Sebagai Medium Pembawa

    OpenAIRE

    Harahap, Irwan Pandapotan

    2010-01-01

    The research of the use of bentonit as a carrier for Rhizobium bacteria and the aplication result for mung bean has been done in the Biochemistry, Mathematics and science Faculty, University of north Sumatera, Medan. The aim of this research is to get know the ability of Rhizobium to fixation nitrogen from the air. The isolated of Rhizobium have got by isolated the bacteria with selective media, by using Yeast Ekstract Manitol Agar (YEMA) and congo red. The isolated of Rhizobium inoculated to...

  7. Impacto de la recombinación homóloga en genomas de Rhizobium etli /

    OpenAIRE

    Acosta Rodríguez, José Luis sustentante.

    2012-01-01

     tesis que para obtener el grado de Doctor en Ciencias presenta: José Luis Acosta Rodríguez ; director de tesis Dr. Víctor Manuel González Zúñiga136 páginas : ilustracionesDoctorado en Ciencias (Biomédicas) Universidad Nacional Autónoma de México, 2012 Centro de Ciencias Genómicas

  8. Rhizobium taibaishanense sp. nov., isolated from a root nodule of Kummerowia striata.

    Science.gov (United States)

    Yao, Li Juan; Shen, Yao Yao; Zhan, Jun Peng; Xu, Wei; Cui, Guang Ling; Wei, Ge Hong

    2012-02-01

    During a study of the diversity and phylogeny of rhizobia in the root nodules of Kummerowia striata grown in north-western China, four strains were classified in the genus Rhizobium on the basis of their 16S rRNA gene sequences. The 16S rRNA gene sequences of three of these strains were identical and that of the other strain, which was the only one isolated in Yangling, differed from the others by just 1 bp. The16S rRNA gene sequences of the four strains showed a mean similarity of 99.3 % with the most closely related, recognized species, Rhizobium vitis. The corresponding recA and glnA gene sequences showed similarities with established species of Rhizobium of less than 86.5 % and less than 89.6 %, respectively. These low similarities indicated that the four strains represented a novel species of the genus Rhizobium. The strains were also found to be distinguishable from the closest related, established species (R. vitis) by rep-PCR DNA fingerprinting, analysis of cellular fatty acid profiles and from the results of a series of phenotypic tests. The level of DNA-DNA relatedness between the representative strain CCNWSX 0483(T) and Rhizobium vitis IAM 14140(T) was only 40.13 %. Therefore, a novel species, Rhizobium taibaishanense sp. nov., is proposed, with strain CCNWSX 0483(T) ( = ACCC 14971(T) = HAMBI 3214(T)) as the type strain. In nodulation and pathogenicity tests, none of the four strains of Rhizobium taibaishanense sp. nov. was able to induce any nodule or tumour formation on plants. As no amplicons were detected when DNA from the strains was run in PCR with primers for the detection of nodA, nifH and virC gene sequences, the strains probably do not carry sym or vir genes.

  9. The use of mycorrhiza and Rhizobium in the growth of three months saga seedling (Adenanthera pavonina

    Directory of Open Access Journals (Sweden)

    Rina Kurniaty

    2017-03-01

    Full Text Available Abstrak. Kurniaty R. 2016. The use of mycorrhiza and Rhizobium in the growth of three months saga seedling (Adenanthera pavonina. Pros Sem Nas Masy Biodiv Indon 2: 6-9. Plants saga tree (Adenanthera pavonina having benefits versatile because almost all parts of crop can be used so that economically valuable high. Wood saga can be used as building material and furniture . Seeds saga have the potential who has a promising as renewable energy source of them because the seeds his containing 14-28% fatty oil who could be classified as non food . In addition oil derived from the seeds of the saga is also very good to treat a disease in, scurvy, injuries, making candles, batik industry, and materials making soap. Research aims to understand the influence of the use of mycorrhizal and Rhizobium in growth seedlings saga age 3 months. Inoculating Rhizobium liquid as many as 1 mL by means of injecting on roots and plants surrounding the hole . The provision of mycorrhizal done by entering 2 g mycorrhizal (Glomus sp into a hole plant at the same time as Rhizobium. Design used is a random factorials consisting of two factors treatment. The first is Rhizobium (A namely: A1 = control and A2= Rhizobium sp. The second factor is mycorrhizal (B consisting of two the standard: B1 = control and B2 = Glomus sp (2 g/ polybag. The results showed that the treatment A2B2 (Rhizobium + mycorrhizal put a value colonization roots highest namely 68,88% with live percent 99,26%, height 10,08 cm, diameter 1.67mm, biomass 0,56 g, TR ratio 2.01 and IMB 0,06 . Nutrient absorption, treatment A2B2 is the nutrient in N 60,30% compared to control, the nutrient P 66,66% compared to control and the nutrient K 123,17% compared to control.

  10. 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)).

  11. Rhizobium tarimense sp. nov., isolated from soil in the ancient Khiyik River.

    Science.gov (United States)

    Turdahon, Maripat; Osman, Ghenijan; Hamdun, Maryam; Yusuf, Khayir; Abdurehim, Zumret; Abaydulla, Gulsumay; Abdukerim, Muhtar; Fang, Chengxiang; Rahman, Erkin

    2013-07-01

    A Gram-negative, non-motile, pale-yellow, rod-shaped bacterial strain, PL-41(T), was isolated from Populus euphratica forest soil at the ancient Khiyik River valley in Xinjiang Uyghur Autonomous Region, People's Republic of China. Strain PL-41(T) grew optimally at 30 °C and pH 7.0-8.0. The major quinone was Q-10. The predominant cellular fatty acids of strain PL-41(T) were summed feature 8 (comprising C18 : 1ω7c and C18 : 1ω6c), C16 : 0 and C19 : 0 cyclo ω8c. Polar lipids of strain PL-41(T) include two unidentified aminophospholipids (APL1, 2), two unidentified phospholipids (PL1, 2), phosphatidylcholine and three unidentified lipids (L1-3). Strain PL-41(T) showed 16S rRNA gene sequence similarity of 97.0-97.5 % to the type strains of recognized species of the genus Rhizobium. Phylogenetic analysis of strain PL-41(T) based on the sequences of housekeeping genes recA and atpD confirmed (similarities are less than 90 %) its position as a distinct species of the genus Rhizobium. The DNA G+C content was 57.8 mol%. DNA-DNA relatedness between strain PL-41(T) and the type strains of Rhizobium huautlense S02(T), Rhizobium alkalisoli CCBAU 01393(T), Rhizobium vignae CCBAU 05176(T) and Rhizobium loessense CCBAU 7190B(T) were 33.4, 22.6, 25.5 and 45.1 %, respectively, indicating that strain PL-41(T) was distinct from them genetically. Strain PL-41(T) also can be differentiated from these four phylogenetically related species of the genus Rhizobium by various phenotypic properties. On the basis of phenotypic properties, phylogenetic distinctiveness and genetic data, strain PL-41(T) is considered to represent a novel species of the genus Rhizobium, for which the name Rhizobium tarimense sp. nov. is proposed. The type strain is PL-41(T) ( = CCTCC AB 2011011(T) = NRRL B-59556(T)).

  12. Mapping the genetic basis of symbiotic variation in legume-rhizobium interactions in Medicago truncatula.

    Science.gov (United States)

    Gorton, Amanda J; Heath, Katy D; Pilet-Nayel, Marie-Laure; Baranger, Alain; Stinchcombe, John R

    2012-11-01

    Mutualisms are known to be genetically variable, where the genotypes differ in the fitness benefits they gain from the interaction. To date, little is known about the loci that underlie such genetic variation in fitness or whether the loci influencing fitness are partner specific, and depend on the genotype of the interaction partner. In the legume-rhizobium mutualism, one set of potential candidate genes that may influence the fitness benefits of the symbiosis are the plant genes involved in the initiation of the signaling pathway between the two partners. Here we performed quantitative trait loci (QTL) mapping in Medicago truncatula in two different rhizobium strain treatments to locate regions of the genome influencing plant traits, assess whether such regions are dependent on the genotype of the rhizobial mutualist (QTL × rhizobium strain), and evaluate the contribution of sequence variation at known symbiosis signaling genes. Two of the symbiotic signaling genes, NFP and DMI3, colocalized with two QTL affecting average fruit weight and leaf number, suggesting that natural variation in nodulation genes may potentially influence plant fitness. In both rhizobium strain treatments, there were QTL that influenced multiple traits, indicative of either tight linkage between loci or pleiotropy, including one QTL with opposing effects on growth and reproduction. There was no evidence for QTL × rhizobium strain or genotype × genotype interactions, suggesting either that such interactions are due to small-effect loci or that more genotype-genotype combinations need to be tested in future mapping studies.

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

    Science.gov (United States)

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

    2015-09-01

    Bacterial strains ZYY136(T) and ZYY9 were isolated from surface-sterilized rice roots from a long-term experiment of rice-rice--Astragalus sinicus rotation. The 16S rRNA gene sequences of strains ZYY136(T) and ZYY9 showed the highest similarity, of 97.0%, to Rhizobium tarimense PL-41(T). Sequence analysis of the housekeeping genes recA, thrC and atpD clearly differentiated the isolates from currently described species of the genus Rhizobium. The DNA-DNA relatedness value between ZYY136(T) and ZYY9 was 82.3%, and ZYY136(T) showed 34.0% DNA-DNA relatedness with the most closely related type strain, R. tarimense PL-41(T). The DNA G+C content of strain ZYY136(T) was 58.1 mol%. The major cellular fatty acids were summed feature 8 (C18 : 1ω7c and/or C18 : 1ω6c), C16 : 0 and C16 : 0 3-OH. Strains ZYY136(T) and ZYY9 could be differentiated from the previously defined species of the genus Rhizobium by several phenotypic characteristics. Therefore, we conclude that strains ZYY136(T) and ZYY9 represent a novel species of the genus Rhizobium, for which the name Rhizobium oryzicola sp. nov. is proposed (type strain ZYY136(T) = ACCC 05753(T) = KCTC 32088(T)).

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

    DEFF Research Database (Denmark)

    Skøt, Leif

    1983-01-01

    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......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...... 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....

  15. 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.

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

    Science.gov (United States)

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

    2015-01-01

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

  17. [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.

  18. 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.

  19. Rhizobium skierniewicense sp. nov., isolated from tumours on chrysanthemum and cherry plum.

    Science.gov (United States)

    Puławska, Joanna; Willems, Anne; Sobiczewski, Piotr

    2012-04-01

    Three isolates of Gram-negative, rod-shaped, non-spore-forming bacteria were recovered from galls on chrysanthemum (Chrysanthemum L.; Ch11T, Ch12) and cherry plum (Prunus cerasifera var. divaricata; AL9.3). All three isolates were able to cause crown galls on various plant species. Phylogenetic analysis based on 16S rRNA gene sequences indicated that the three isolates were probably identical (100% sequence similarity) and closely related to Rhizobium rubi (99.6 %), Rhizobium radiobacter (98.7 %) and Rhizobium larrymoorei (98.1 %). Similar analysis based on the housekeeping genes glnA, gyrB and rpoB also indicated that the novel isolates were identical and closely related to R. rubi. The major cellular fatty acids of strain Ch11T were C18:1ω7c (62.1 %), summed feature 2 (comprising C12:0 aldehyde, iso-C16:1 I and/or C14:0 3-OH; 10.8 %), summed feature 3 (comprising C16:1ω7c and/or iso-C15:0 2-OH; 7.7 %) and C10:0 3-OH (7.5 %). However, the DNA-DNA relatedness between Ch11T and R. rubi LMG 156T was only 48 % and, unlike phylogenetically related established Rhizobium species, the novel isolates were able to utilize β-hydroxybutyric acid but not L-fucose. Based on the phylogenetic and phenotypic evidence, the isolates are considered to represent a single novel species of the genus Rhizobium, for which the name Rhizobium skierniewicense sp. nov. is proposed; the type strain is Ch11T (=LMG 26191T=CFBP 7420T).

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

    Science.gov (United States)

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

    2012-06-01

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

  1. Rhizobium azibense sp. nov., a nitrogen fixing bacterium isolated from root-nodules of Phaseolus vulgaris.

    Science.gov (United States)

    Mnasri, Bacem; Liu, Tian Yan; Saidi, Sabrine; Chen, Wen Feng; Chen, Wen Xin; Zhang, Xiao Xia; Mhamdi, Ridha

    2014-05-01

    Three microbial strains isolated from common beans, 23C2T (Tunisia), Gr42 (Spain) and IE4868 (Mexico), which have been identified previously as representing a genomic group closely related to Rhizobium gallicum, are further studied here. Their 16S rRNA genes showed 98.5-99% similarity with Rhizobium loessense CCBAU 7190BT, R. gallicum R602spT, Rhizobium mongolense USDA 1844T and Rhizobium yanglingense CCBAU 71623T. Phylogenetic analysis based on recA, atpD, dnaK and thrC sequences showed that the novel strains were closely related and could be distinguished from the four type strains of the closely related species. Strains 23C2T, Gr42 and IE4868 could be also differentiated from their closest phylogenetic neighbours by their phenotypic and physiological properties and their fatty acid contents. All three strains harboured symbiotic genes specific to biovar gallicum. Levels of DNA-DNA relatedness between strain 23C2T and the type strains of R. loessense, R. mongolense, R. gallicum and R. yanglingense ranged from 58.1 to 61.5%. The DNA G+C content of the genomic DNA of strain 23C2T was 59.52%. On the basis of these data, strains 23C2T, Gr42 and IE4868 were considered to represent a novel species of the genus Rhizobium for which the name Rhizobium azibense is proposed. Strain 23C2T (=CCBAU 101087T=HAMBI3541T) was designated as the type strain.

  2. Rhizobium pusense sp. nov., isolated from the rhizosphere of chickpea (Cicer arietinum L.).

    Science.gov (United States)

    Panday, Digvijay; Schumann, Peter; Das, Subrata K

    2011-11-01

    A novel bacterial strain, designated NRCPB10(T), was isolated from rhizosphere soil of chickpea (Cicer arietinum L.) in Pusa, New Delhi, India. The 16S rRNA gene sequence of strain NRCPB10(T) showed highest similarity (98.9 %) to that of Rhizobium radiobacter NCPPB 2437(T), followed by Rhizobium larrymoorei AF3-10(T) (97.7 %) and Rhizobium rubi IFO 13261(T) (97.4 %). Phylogenetic analysis of strain NRCPB10(T) based on the housekeeping genes recA and atpD confirmed its position as distinct from recognized Rhizobium species. Levels of DNA-DNA relatedness between strain NRCPB10(T) and R. radiobacter ICMP 5785(T), R. larrymoorei LMG 21410(T) and R. rubi ICMP 6428(T) were 51.0, 32.6 and 27.3 %, respectively. Cellular fatty acids of strain NRCPB10(T) were C(18 : 1)ω7c (58.9 %), C(16 : 0) (15.5 %), C(19 : 0) cyclo ω8c (11.5 %), iso-C(16 : 1) (5.8 %), C(16 : 0) 3-OH (4.5 %), C(16 : 1)ω7c (2.1 %) and C(18 : 0) (1.3 %). The G+C content of the genomic DNA of strain NRCPB10(T) was 59.0 mol%. Strain NRCPB10(T) did not nodulate chickpea plants or induce tumours in tobacco plants. Phenotypic and physiological properties along with SDS-PAGE of whole-cell soluble proteins differentiated strain NRCPB10(T) from its closest phylogenetic neighbours. On the basis of data from the present polyphasic taxonomic study, strain NRCPB10(T) is considered to represent a novel species of the genus Rhizobium, for which the name Rhizobium pusense sp. nov. is proposed. The type strain is NRCPB10(T) ( = LMG 25623(T) = JCM 16209(T) = NCIMB 14639(T)).

  3. Strain identification and quorum sensing inhibition characterization of marine-derived Rhizobium sp. NAO1

    Science.gov (United States)

    Chang, Hong; Zhu, Xiaoshan; Yu, Shenchen; Chen, Lu; Jin, Hui; Cai, Zhonghua

    2017-01-01

    A novel strategy for combating pathogens is through the ongoing development and use of anti-quorum sensing (QS) treatments such as therapeutic bacteria or their anti-QS substances. Relatively little is known about the bacteria that inhabit the open ocean and of their potential anti-pathogenic attributes; thus, in an initiative to identify these types of therapeutic bacteria, planktonic microbes from the North Atlantic Ocean were collected, isolated, cultured and screened for anti-QS activity. Screening analysis identified one such strain, Rhizobium sp. NAO1. Extracts of Rhizobium sp. NAO1 were identified via ultra-performance liquid chromatography (UPLC) analysis. They were shown to contain N-acyl homoserine lactone (AHL)-based QS analogues (in particular, the N-butyryl homoserine lactone (C4-AHL) analogue) and could disrupt biofilm formation by Pseudomonas aeruginosa PAO1. QS inhibition was confirmed using confocal scanning laser microscopy and growth curves, and it was shown to occur in a dose-dependent manner without affecting bacterial growth. Secondary metabolites of Rhizobium sp. NAO1 inhibited PAO1 pathogenicity by downregulating AHL-mediated virulence factors such as elastase activity and siderophore production. Furthermore, as a result of biofilm structure damage, the secondary metabolite products of Rhizobium sp. NAO1 significantly increased the sensitivity of PAO1 to aminoglycoside antibiotics. Our results demonstrated that Rhizobium sp. strain NAO1 has the ability to disrupt P. aeruginosa PAO1 biofilm architecture, in addition to attenuating P. aeruginosa PAO1 virulence factor production and pathogenicity. Therefore, the newly identified ocean-derived Rhizobium sp. NAO1 has the potential to serve as a QS inhibitor and may be a new microbial resource for drug development.

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

    Directory of Open Access Journals (Sweden)

    2009-06-01

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

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

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

    Science.gov (United States)

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

    2016-01-01

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

  6. 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 Rhizobium species. The major fatty acids in strain CC-SKC2(T) were C16:0, C19:0 cyclo ω8c, C14:0 3-OH and/or C16:1 iso I and C18:1 ω7c and/or C18:1 ω6c. 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)).

  7. Rhizobium altiplani sp. nov., isolated from effective nodules on Mimosa pudica growing in untypically alkaline soil in central Brazil.

    Science.gov (United States)

    Baraúna, Alexandre C; Rouws, Luc F M; Simoes-Araujo, Jean L; Dos Reis Junior, Fábio B; Iannetta, Pietro P M; Maluk, Marta; Goi, Silvia R; Reis, Veronica M; James, Euan K; Zilli, Jerri E

    2016-10-01

    Root nodule bacteria were isolated from nodules on Mimosa pudica L. growing in neutral-alkaline soils from the Distrito Federal in central Brazil. The 16S rRNA gene sequence analysis of 10 strains placed them into the genus Rhizobium with the closest neighbouring species (each with 99 % similarity) being Rhizobium grahamii, Rhizobium cauense, Rhizobium mesoamericanum and Rhizobium tibeticum. This high similarity, however, was not confirmed by multi-locus sequence analysis (MLSA) using three housekeeping genes (recA, glnII and rpoB), which revealed R. mesoamericanum CCGE 501T to be the closest type strain (92 % sequence similarity or less). Chemotaxonomic data, including fatty acid profiles [with majority being C19 : 0 cyclo ω8c and summed feature 8 (C18 : 1ω7c/C18 : 1ω6c)], DNA G+C content (57.6 mol%), and carbon compound utilization patterns supported the placement of the novel strains in the genus Rhizobium. Results of average nucleotide identity (ANI) differentiated the novel strains from the closest species of the genus Rhizobium, R. mesoamericanum, R. grahamii and R. tibeticum with 89.0, 88.1 and 87.8 % similarity, respectively. The symbiotic genes essential for nodulation (nodC) and nitrogen fixation (nifH) were most similar (99-100 %) to those of R. mesoamericanum, another Mimosa-nodulating species. Based on the current data, these 10 strains represent a novel species of the genus Rhizobium for which the name Rhizobium altiplani sp. nov. is proposed. The type strain is BR 10423T (=HAMBI 3664T).

  8. Genetic regulation of nitrogen fixation in Rhizobium meliloti.

    Science.gov (United States)

    Cebolla, A; Palomares, A J

    1994-12-01

    The soil bacterium Rhizobium meliloti fixes dinitrogen when associated with root nodules formed on its plant host, Medicago sativa (alfalfa). The expression of most of the known genes required for nitrogen fixation (nif and fix genes), including the structural genes for nitrogenase, is induced in response to a decrease in oxygen concentration. Induction of nif and fix gene expression by low oxygen is physiologically relevant because a low-oxygen environment is maintained in root nodules to prevent inactivation of the highly oxygen-sensitive nitrogenase enzyme. The genes responsible for sensing and transducing the low oxygen signal, fixL and fixJ, encode proteins (FixL and FixJ, respectively) that are homologous to a large family of bacterial proteins involved in signal transduction, the two component regulatory system proteins. The two components consist of a sensor protein, to which FixL is homologous, and a response regulator protein, to which FixJ is homologous. The sensor protein respond to an activating signal by autophosphorylating and then transferring the phosphate to its cognate response regulator protein. The phosphorylated response regulator, which is often a transcriptional activator, is then able to activate its target. A cascade model of nif and fix gene regulation in R. meliloti has been proposed, whereby FixL acts as an oxygen sensor as the initial event in the cascade and transmits this information to FixJ. FixJ, which possesses a putative helix-turn-helix DNA-binding motif, then activates transcription of the nifA and fixK genes. The nifA and fixK gene products, are transcriptional activators of at least 14 other nif and fix genes.

  9. Nod factor signaling genes and their function in the early stages of Rhizobium infection

    NARCIS (Netherlands)

    Geurts, R.; Fedorova, E.; Bisseling, T.

    2005-01-01

    A lipochitosaccharide-based signal molecule that is secreted by Rhizobium, named Nod factor (NF), induces root nodule formation in legumes. This molecule is also essential for the establishment of bacterial infection. Genetic analyses in the legume species Lotus japonicus and Medicago truncatula hav

  10. Perception and action of nod factors in Rhizobium-legume symbiosis.

    NARCIS (Netherlands)

    Heidstra, R.

    1997-01-01

    Rhizobium bacteria are able to invade the roots of their leguminous hosts and trigger the formation of a new organ, the root nodule. In these nodules the bacteria are hosted in the proper environment for fixing atmospheric nitrogen into ammonia, making plant growth independent of nitrogen compounds

  11. Characterization of the nifA regulatory gene of Rhizobium leguminosarum PRE.

    NARCIS (Netherlands)

    Roelvink, P.W.

    1989-01-01

    This thesis describes the characterization of the nif A regulatory gene of the pea endosymbiont Rhizobiumleguminosarum PRE.Chapter I gives a general overview on the regulation of nitrogen fixation in diazotrophs, with special focus on the regulatory NifA pr

  12. Distribution of a Population of Rhizobium leguminosarum bv. trifolii among Different Size Classes of Soil Aggregates†

    OpenAIRE

    Mendes, Ieda C.; Bottomley, Peter J.

    1998-01-01

    A combination of the plant infection-soil dilution technique (most-probable-number [MPN] technique) and immunofluorescence direct count (IFDC) microscopy was used to examine the effects of three winter cover crop treatments on the distribution of a soil population of Rhizobium leguminosarum bv. trifolii across different size classes of soil aggregates (

  13. Nitrogen fixation by Rhizobium leguminosarum PRE; a genetical and biochemical approach.

    NARCIS (Netherlands)

    Klein Lankhorst, R.

    1989-01-01

    Nitrogen fix ation by Rhizobium and Bradyrhizobium bacteria in symbiosis with their leguminous host plants forms an attractive alternative for the industrial production of nitrogenous fertilizers, both from an economic as well as an enviromnental point of view, and is the topic of many scientific re

  14. 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. ...

  15. Genome Sequence of the Symbiotic Type Strain Rhizobium tibeticum CCBAU85039T

    Science.gov (United States)

    Wibberg, Daniel; Winkler, Anika; Ormeño-Orrillo, Ernesto; Martínez-Romero, Esperanza; Niehaus, Karsten; Pühler, Alfred; Kalinowski, Jörn; Lagares, Antonio; Schlüter, Andreas; Pistorio, Mariano

    2017-01-01

    ABSTRACT Rhizobium tibeticum was originally isolated from root nodules of Trigonella archiducis-nicolai grown in Tibet, China. This species is also able to nodulate Medicago sativa and Phaseolus vulgaris. The whole-genome sequence of the type strain, R. tibeticum CCBAU85039T, is reported in this study. PMID:28126941

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

    DEFF Research Database (Denmark)

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

    1990-01-01

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

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

    DEFF Research Database (Denmark)

    Rosendahl, Lis

    1984-01-01

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

  18. 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)).

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

    Science.gov (United States)

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

    2015-09-01

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

  20. 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.

  1. 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...

  2. Effect of Rhizobium inoculation and phosphorus application on native Texas legumes grown in local soil

    NARCIS (Netherlands)

    Osman, E.; Muir, J.P.; Elgersma, A.

    2002-01-01

    Greenhouse experiments were conducted to determine the effects of Rhizobium inoculation and addition of phosphorus to soil on the productivity and quality of the Texas range legumes Desmanthus illinoiensis (Michx.) MacMill. ex B.L. Rob. & Fernald, Desmanthus velutinus Scheele, Desmanthus

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

    DEFF Research Database (Denmark)

    Rosendahl, Lis

    1984-01-01

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

  4. The symbiosis between Rhizobium leguminosarum and Pisum savitum: regulation of the nitrogenase activity.

    NARCIS (Netherlands)

    Appels, M.A.

    1989-01-01

    Bacteria of the genus Rhizobium can form a symbiosis with plants of the family Leguminosae. Both bacteria and plant show considerable biochemical and morphological changes in order to develop and carry out the symbiosis. The Rhizobia induce special structures on the legumes, which are called root no

  5. Effect of Rhizobium inoculation and phosphorus application on native Texas legumes grown in local soil

    NARCIS (Netherlands)

    Osman, E.; Muir, J.P.; Elgersma, A.

    2002-01-01

    Greenhouse experiments were conducted to determine the effects of Rhizobium inoculation and addition of phosphorus to soil on the productivity and quality of the Texas range legumes Desmanthus illinoiensis (Michx.) MacMill. ex B.L. Rob. & Fernald, Desmanthus velutinus Scheele, Desmanthus virgatus (L

  6. The symbiosis between Rhizobium leguminosarum and Pisum sativum : regulation of the nitrogenase activity

    NARCIS (Netherlands)

    Appels, M.A.

    1989-01-01

    Bacteria of the genus Rhizobium can form a symbiosis with plants of the family Leguminosae. Both bacteria and plant show considerable biochemical and morphological changes in order to develop and carry out the symbiosis. The Rhizobia

  7. Rhizoplane colonisation of peas by Rhizobium leguminosarum bv. viceae and a deleterious Pseudomonas putida

    NARCIS (Netherlands)

    Berggren, I.; Alstrom, S.; Vuurde, van J.W.L.; Martensson, A.M.

    2005-01-01

    Pseudomonas putida strain angstrom 313, a deleterious rhizosphere bacterium, reduced pea nitrogen content when inoculated alone or in combination with Rhizobium leguminosarum bv. viceae on plants in the presence of soil under greenhouse conditions. When plants were grown gnotobiotically in liquid me

  8. Rhizobium populi sp. nov., an endophytic bacterium isolated from Populus euphratica.

    Science.gov (United States)

    Rozahon, Manziram; Ismayil, Nurimangul; Hamood, Buayshem; Erkin, Raziya; Abdurahman, Mehfuzem; Mamtimin, Hormathan; Abdukerim, Muhtar; Lal, Rup; Rahman, Erkin

    2014-09-01

    An endophytic bacterium, designated K-38(T), was isolated from the storage liquid in the stems of Populus euphratica trees at the ancient Ugan River in Xinjiang, PR China. Strain K-38(T) was found to be rod-shaped, Gram-stain-negative, aerobic, non-motile and non-spore-forming. Strain K-38(T) grew at temperatures of 25-37 °C (optimum, 28 °C), at pH 6.0-9.0 (optimum, pH 7.5) and in the presence of 0-3 % (w/v) NaCl with 1 % as the optimum concentration for growth. According to phylogenetic analysis based on 16S rRNA gene sequences, strain K-38(T) was assigned to the genus Rhizobium with highest 16S rRNA gene sequence similarity of 97.2 % to Rhizobium rosettiformans W3(T), followed by Rhizobium nepotum 39/7(T) (96.5 %) and Rhizobium borbori DN316(T) (96.2 %). Phylogenetic analysis of strain K-38(T) based on the protein coding genes recA, atpD and nifH confirmed (similarities were less than 90 %) it to be a representative of a distinctly delineated species of the genus Rhizobium. The DNA G+C content was determined to be 63.5 mol%. DNA-DNA relatedness between K-38(T) and R. rosettiformans W3(T) was 48.4 %, indicating genetic separation of strain K-38(T) from the latter strain. The major components of the cellular fatty acids in strain K-38(T) were revealed to be summed feature 8 (comprising C18 : 1ω7c and/or C18 : 1ω6c; 57.2 %), C16 : 0 (13.6 %) and summed feature 2 (comprising C12 : 0 aldehyde, C14 : 0 3-OH/iso-C16 : 1 I and/or unknown ECL 10.928; 11.0 %). Polar lipids of strain K-38(T) include phosphatidylethanolamine, phosphatidylmonomethylethanolamine, phosphatidylcholine, phosphatidylglycerol, diphosphatidylglycerol, two unidentified aminophospholipids and two unidentified phospholipids. Q-10 was the major quinone in strain K-38(T). Based on phenotypic, chemotaxonomic and phylogenetic properties, strain K-38(T) represents a novel species of the genus Rhizobium, for which the name Rhizobium populi sp. nov. is proposed

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

    Science.gov (United States)

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

    2015-12-01

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

  10. The nodC, nodG, and glgX genes of Rhizobium tropici strain PRF 81.

    Science.gov (United States)

    Oliveira, Luciana Ruano; Marcelino, Francismar Corrêa; Barcellos, Fernando Gomes; Rodrigues, Elisete Pains; Megías, Manuel; Hungria, Mariangela

    2010-08-01

    Rhizobium tropici is a diazotrophic microsymbiont of common bean (Phaseolus vulgaris L.) that encompasses important but still poorly studied tropical strains, and a recent significant contribution to the knowledge of the species was the publication of a genomic draft of strain PRF 81, which revealed several novel genes [Pinto et al. Funct Int Gen 9:263-270, 2009]. In this study, we investigated the transcription of nodC, nodG, and glgX genes, located in the nod operon of PRF 81 strain, by reverse-transcription quantitative PCR. All three genes showed low levels of transcription when the cells were grown until exponential growth phase in the presence of common-bean-seed exudates or of the root nod-gene inducer naringenin. However, when cells at the exponential phase of growth were incubated with seed exudates, transcription occurred after only 5 min, and nodC, nodG, and glgX were transcribed 121.97-, 14.86-, and 50.29-fold more than the control, respectively, followed by a rapid decrease in gene transcription. Much lower levels of transcription were observed in the presence of naringenin; furthermore, maximum transcription required 8 h of incubation for all three genes. In light of these results, the mechanisms of induction of the nodulation genes by flavonoids are discussed.

  11. Rhizobium strains competitiveness on bean nodulation in Cerrado soils Capacidade competitiva de estirpes de Rhizobium na nodulação do feijoeiro em solos de Cerrado

    Directory of Open Access Journals (Sweden)

    Ruy Raposeiras

    2006-03-01

    Full Text Available The objective of this work was to identify the most competitive and effective Rhizobium strains in order to increase common bean yield by nitrogen fixation as alternative or complementation to the nitrogen fertilization. Competitiveness tests were lead in axenic conditions, in Cerrado soil pots and in three field experiments, with native Rhizobium strains that were previously identified, according to their effectiveness and genetic variability. The identification of strains in nodules was performed using serological tests (axenic conditions - agglutination and enzyme linked immunosorbent (Elisa assays - and random amplified polymorfic DNA (RAPD (Cerrado soil. Plant yield was determined using the dry weight (greenhouse conditions, total N and grain yield (field experiments. Among the analyzed Rhizobium strains, native strain SLA 2.2 and commercial strain CIAT 899 were the dominant nodules in plants of the most productive plots, presenting yield productivity similar or higher to those obtained in treatments where 20 kg ha-1 of N were applied.O objetivo deste trabalho foi identificar as estirpes de Rhizobium mais efetivas e competitivas, a fim de maximizar a produtividade do feijoeiro por meio da fixação de nitrogênio, como alternativa à adubação nitrogenada. Foram conduzidos testes de competitividade em condições axênicas, em vasos com solo do Cerrado e em três experimentos de campo, com estirpes de Rhizobium nativas, previamente selecionadas quanto à efetividade e à variabilidade genética. A identificação das estirpes nos nódulos foi efetuada por meio das técnicas de aglutinação e ensaio imunoabsorvente de ligação de enzimas (Elisa, em condições de casa de vegetação, e pela técnica de DNA polimórfico amplificado ao acaso (RAPD, em solo de Cerrado. A produtividade das plantas foi determinada pela produção de matéria seca, teor de N e produção de grãos (condições de campo. A estirpe nativa SLA 2.2 e a estirpe

  12. Rhizobium straminoryzae sp. nov., isolated from the surface of rice straw.

    Science.gov (United States)

    Lin, Shih-Yao; Hsu, Yi-Han; Liu, You-Cheng; Hung, Mei-Hua; Hameed, Asif; Lai, Wei-An; Yen, Wen-Shao; Young, Chiu-Chung

    2014-09-01

    An aerobic, Gram-stain-negative, rod-shaped bacterium, designated strain CC-LY845(T), was isolated from the surface of rice straw in Taiwan. Cells were non-motile, and no flagellum was detected. Comparison of 16S rRNA gene sequences indicated that the strain was phylogenetically related to species of the genus Rhizobium, with closest similarity to Rhizobium pseudoryzae KCTC 23294(T) (97.6 %), R. rhizoryzae KCTC 23652(T) (97.0 %) and R. oryzae LMG 24253(T) (96.7 %); other species showed lower levels of similarity (Rhizobium. The temperature range for growth was 25-42 °C, the pH range was 5.0-9.0 and NaCl concentrations up to 4.0 % (w/v) were tolerated. Strain CC-LY845(T) did not form nodules on four different legumes, and the nodD and nifH genes were not detected by PCR. The major fatty acids were C16 : 0 and summed feature 8 (C18 : 1ω7c/C18 : 1ω6c). The polyamine pattern of strain CC-LY845(T) showed spermidine and putrescine as major polyamines. The predominant quinone system was ubiquinone 10 (Q-10). The DNA G+C content was 68.3±2.4 mol%. Base on its phylogenetic, phenotypic and chemotaxonomic features, strain CC-LY845(T) is proposed to represent a novel species within the genus Rhizobium, for which the name Rhizobium straminoryzae sp. nov. is proposed. The type strain is strain CC-LY845(T) ( = BCRC 80698(T) = JCM 19536(T)).

  13. Rhizobium subbaraonis sp. nov., an endolithic bacterium isolated from beach sand.

    Science.gov (United States)

    Ramana, Ch V; Parag, B; Girija, K R; Ram, B Raghu; Ramana, V Venkata; Sasikala, Ch

    2013-02-01

    Two strains (JC85(T) and JC108) of Gram-stain-negative, motile bacteria were isolated from endolithic beach sand samples on an oligotrophic medium. Based on the 16S rRNA gene sequence analysis, both strains were identified as belonging to the genus Rhizobium. Strain JC108 had 16S rRNA gene sequence similarity of 100 % with Rhizobium pusense NRCPB10(T) and formed a cluster with this strain. Strain JC85(T) had 96.9 % 16S rRNA gene sequence similarity and was 18 % related (based on DNA-DNA hybridization) to Rhizobium borbori DN316(T). With other strains of the genus Rhizobium, the 16S rRNA gene sequence similarity was less than 96.3 %. Strain JC85(T) could tolerate up to 3 % salinity, fix N(2), was resistant to ampicillin (10 µg) and was positive for catalase and oxidase. The major fatty acid was C(18 : 1)ω7c (69 %) with minor amounts of C(19 : 0) cyclo ω8c (8.9 %), C(16 : 0) (6.9 %), C(12 : 0) (5.7 %) and C(19 : 1)ω7c/C(19 : 1)ω6c (2.2 %). Polar lipids of strain JC85(T) include two unidentified aminophospholipids (APL1,2), two unidentified phospholipids (PL1,2), phosphatidylcholine and four unidentified lipids (L1-4). Q-10 is the major quinone of strain JC85(T). Based on polyphasic taxonomic analysis, strain JC85(T) represents a novel species for which, the name Rhizobium subbaraonis JC85(T) is proposed. The type strain is JC85(T) ( = DSM 24765(T) = KCTC 23614(T)).

  14. Rhizobium smilacinae sp. nov., an endophytic bacterium isolated from the leaf of Smilacina japonica.

    Science.gov (United States)

    Zhang, Lei; Shi, Xu; Si, Meiru; Li, Changfu; Zhu, Lingfang; Zhao, Liang; Shen, Xihui; Wang, Yao

    2014-10-01

    During a study of endophytic bacteria from traditional Chinese medicinal plants, a bacterial strain, designated PTYR-5(T), was isolated from the leaf of Smilacina japonica A. Gray collected from Taibai Mountain in Shaanxi Province, north-west China. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain PTYR-5(T) is a member of the genus Rhizobium, exhibiting the highest sequence similarities to R. cellulosilyticum LMG 23642(T) (97.2%), R. huautlense LMG 18254(T) (97.2%) and R. alkalisoli CCBAU 01393(T) (97.1%). The levels of 16S rRNA gene sequence similarity with respect to other Rhizobium species with validly published names were less than 97.0%. Phylogenies of the housekeeping genes atpD, recA and glnII confirmed its distinct position, showing low similarity with respect to those of recognized Rhizobium species (no more than 94.1, 90.0 and 88.0% similarity, respectively). The DNA-DNA relatedness values of strain PTYR-5(T) with R. cellulosilyticum LMG 23642(T), R. huautlense LMG 18254(T) and R. alkalisoli CCBAU 01393(T) were 33.6, 21.4 and 29.5 %, respectively. Based on phenotypic, phylogenetic and genotypic data, strain PTYR-5(T) is considered to represent a novel species of the genus Rhizobium, for which the name Rhizobium smilacinae sp. nov. is proposed. The type strain is PTYR-5(T) (=CCTCC AB 2013016(T)=KCTC 32300(T)=LMG 27604(T)).

  15. 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.

  16. High-quality draft genome sequence of Rhizobium mesoamericanum strain STM6155, a Mimosa pudica microsymbiont from New Caledonia

    National Research Council Canada - National Science Library

    Klonowska, Agnieszka; López-López, Aline; Moulin, Lionel; Ardley, Julie; Gollagher, Margaret; Marinova, Dora; Tian, Rui; Huntemann, Marcel; Reddy, T.B.K; Varghese, Neha; Woyke, Tanja; Markowitz, Victor; Ivanova, Natalia; Seshadri, Rekha; Baeshen, Mohamed N; Baeshen, Nabih A; Kyrpides, Nikos; Reeve, Wayne

    2017-01-01

      Rhizobium mesoamericanum STM6155 (INSCD = ATYY01000000) is an aerobic, motile, Gram-negative, non-spore-forming rod that can exist as a soil saprophyte or as an effective nitrogen fixing microsymbiont of the legume Mimosa pudica L...

  17. Preservation of rhizobia by lyophilization with trehalose Preservação de rizóbio por liofilização com trealose

    Directory of Open Access Journals (Sweden)

    Pedro Antonio Arraes Pereira

    2002-06-01

    Full Text Available The objective of this study was to determine if trehalose can effectively enhance the viability and storage lifetime of Rhizobium tropici and Rhizobium etli after lyophilization as compared to the traditional protective combination of sucrose and peptone. Two strains of bean-nodulating rhizobia were effectively preserved in the lyophilized state by 100 mM trehalose, and survived for at least 12 days, even when stored under non-ideal conditions. Trehalose provided better protection than the sucrose/peptone combination. When protective excipients were introduced inside the cells, strain CFN 42 was more sensitive to the type of additive used than strain CIAT 899, probably because CIAT 899 produces beta (1-2 glucan, which may have a protective effect. beta (1-2 glucan combined with sucrose protected better than trehalose against leakage from freeze-dried liposomes, but by itself it had no protective capability. There was a high level of unfrozen water associated with the hydrated glucan, in addition to a thermal event at approximately 70ºC, corresponding to an observed gel-sol transition in the glucan. These findings may shed light on the mechanism by which the glucan contributes to the protection of dried cells and liposomes, and may lead to further improvements in rhizobial inoculants.O objetivo deste estudo foi determinar se a trealose pode aumentar a viabilidade e o tempo de preservação de estirpes de Rhizobium tropici e Rhizobium etli após a liofilização, comparada com a proteção proporcionada pela combinação tradicional de sacarose e peptona. Duas estirpes de rizóbio para feijão foram preservadas liofilizadas com 100 mM de trealose e sobreviveram por pelo menos 12 dias, mesmo quando armazenadas sob condições não-ideais. A trealose proporcionou uma proteção superior à combinação de sacarose peptona. Quando agentes protetores foram introduzidos dentro da célula, a estirpe CFN 42 foi mais sensível em relação ao tipo de

  18. Rhizobium phenanthrenilyticum sp. nov., a novel phenanthrene-degrading bacterium isolated from a petroleum residue treatment system.

    Science.gov (United States)

    Wen, Ya; Zhang, Juan; Yan, Qiuxiang; Li, Shunpeng; Hong, Qing

    2011-01-01

    Strain F11(T), a phenanthrene-degrading bacterium, was isolated from a petroleum residue treatment system, and classified under the genus Rhizobium based on the similarity analysis of its 16S rRNA and recA gene sequences. Strain F11(T) falls into the same phylogenetic clade with Rhizobium oryzae Alt 505(T) (96.8% 16S rRNA gene sequence similarity) and Rhizobium pseudoryzae J34A-127(T) (96.2%). Major cellular fatty acids of strain F11(T) are C(16:0) (6.24%) and summed feature 8 (C(18:1ω7c) and/or C(18:1ω6c), 76.59%), which are also the major fatty acids of R. oryzae Alt 505(T) and R. pseudoryzae J34A-127(T). The DNA G+C content of strain F11(T) was 59.3±0.4 mol%. Based on the phylogenetic analysis as well as biochemical and physiological characteristics, strain F11(T) could be separated from all recognized Rhizobium species. Strain F11(T) (=DSM 21882(T) =CCTCC AB 209029(T)) was considered to be representative of a novel species of Rhizobium, for which the name Rhizobium phenanthrenilyticum sp. nov. is proposed.

  19. Effects of arbuscular mycorrhizal fungi and Rhizobium on ion content and root characteristics of green bean and maize under intercropping

    Directory of Open Access Journals (Sweden)

    Zahra Marzban

    2017-01-01

    Full Text Available In order to evaluate arbuscular mycorrhizal fungi and rhizobium bacteria effects on leaf nitrogen (N and phosphorus (P concentration and root characteristics of green bean and maize under intercropping, experiment was carried out in the research field of College of Agriculture, Payame Noor University of Azna, Lorestan, Iran. In experiment, sandy loam soil with pH 7.3 and EC 0.49 dS m-1 was used.The treatments comprised three cropping systems (sole cropping of green bean and maize, and intercropping, and four inoculations (control, arbuscular mycorrhizal fungi, rhizobium and mix of arbuscular mycorrhizal fungi and rhizobium. The results showed that inoculation with rhizobium improved length, diameter, volume and area of green bean root.The highest of green bean N, P concentration and root dry mass were observed in sole culture of green bean inoculated with arbuscular mycorrhizal fungi. Moreover, root length, diameter, volume and area of maize increased by arbuscular mycorrhizal fungi, and total concentration of N and P enhanced with use of rhizobium in sole cropping. Although the usage of Rhizobium and AMF can be affected on increasing the root growth and nutrient uptake of crops, application of bacterium and fungi combination at the same time would not be suitable. Overall, intercropping of maize with green bean caused to increase of leaf N and P concentrations and root growth of maize.

  20. ''Et sted''

    DEFF Research Database (Denmark)

    Dinesen, Cort Ross

    2009-01-01

    At arkitekturen er forbundet med og forankret til "et sted" - det at arkitekturen finder sted og at arkitekturen står et sted, - og at arkitekturen sætter en målelighed i det umålelige og skaber permanens er velkendt. Samtidig bevæger vi os fra "sted" til "sted" i værket eller mellem værker og vo...

  1. First genomic analysis of the broad-host-range Rhizobium sp. LPU83 strain, a member of the low-genetic diversity Oregon-like Rhizobium sp. group.

    Science.gov (United States)

    Tejerizo, Gonzalo Torres; Del Papa, María Florencia; Draghi, Walter; Lozano, Mauricio; Giusti, María de Los Ángeles; Martini, Carla; Salas, María Eugenia; Salto, Ileana; Wibberg, Daniel; Szczepanowski, Rafael; Weidner, Stefan; Schlüter, Andreas; Lagares, Antonio; Pistorio, Mariano

    2011-08-20

    Alfalfa (Medicago sativa) is the most cultivated forage legume for cattle and animal feeding, occupying about 32 million hectares over the world. Management of the N₂-fixing symbiosis of this plant to maximize crop production is therefore an important objective. A fundamental constraint to this aim emerges when a moderately low soil pH hampers the establishment of an effective symbiosis with indigenous and/or inoculated rhizobia. Besides the association of alfalfa with Ensifer (Sinorhizobium) meliloti, this legume is able to establish a symbiosis with Ensifer (Sinorhizobium) medicae and with less characterized types of rhizobia, such as the Oregon-like strains, Rhizobium sp. Or191 initially isolated in the USA, and the Rhizobium sp. LPU83 strain, from Argentina. These strains are acid-tolerant, highly competitive for acidic-soil-alfalfa nodulation, but inefficient for biological nitrogen fixation with alfalfa. These features position the Oregon-like rhizobia as strains of potential risk in agricultural soils compared with the efficient symbiont E. meliloti. Moreover, the collected genetic information has revealed that the genomic structure of these rhizobial isolates is complex in terms of sequence similarities shared with other rhizobia. Such a "patched" genetic composition has obviously imposed severe restrictions to the classical taxonomy of these rhizobia. In this work we summarize the accumulated knowledge about the Oregon-like rhizobia and present a phylogenetic analysis based on genome sequence data of Rhizobium sp. LPU83 obtained by a high-throughput sequencing on the Genome Sequencer FLX Titanium platform. The accessibility of the complete genomic sequence will release up more experimental possibilities since this information will then enable biochemical studies as well as proteomics and transcriptomics approaches.

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

    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)

  3. Et hjem

    DEFF Research Database (Denmark)

    Bruun, Maja Hojer

    2014-01-01

    Når folk sætter deres hjem til salg - især når der hersker usikkerhed om værdier og priser som under de seneste års boligkrise - får det os til at tænke over, hvad vilkårene er for at stifte, skabe og genskabe hjem i et moderne markedsbaseret samfund: Den integrerede helhed af personer, ting og...... sted, som hjemmet udgør i hverdagslivet, opløses, når et hjem sættes til salg og gøres til en vare på et boligmarked. Til hjemmets potentiale som vare knytter der sig drømme og forventninger til fremtiden - og i krisetider utryghed og uhygge....

  4. LysM-type mycorrhizal receptor recruited for rhizobium symbiosis in nonlegume Parasponia.

    Science.gov (United States)

    Op den Camp, Rik; Streng, Arend; De Mita, Stéphane; Cao, Qingqin; Polone, Elisa; Liu, Wei; Ammiraju, Jetty S S; Kudrna, Dave; Wing, Rod; Untergasser, Andreas; Bisseling, Ton; Geurts, René

    2011-02-18

    Rhizobium-root nodule symbiosis is generally considered to be unique for legumes. However, there is one exception, and that is Parasponia. In this nonlegume, the rhizobial nodule symbiosis evolved independently and is, as in legumes, induced by rhizobium Nod factors. We used Parasponia andersonii to identify genetic constraints underlying evolution of Nod factor signaling. Part of the signaling cascade, downstream of Nod factor perception, has been recruited from the more-ancient arbuscular endomycorrhizal symbiosis. However, legume Nod factor receptors that activate this common signaling pathway are not essential for arbuscular endomycorrhizae. Here, we show that in Parasponia a single Nod factor-like receptor is indispensable for both symbiotic interactions. Therefore, we conclude that the Nod factor perception mechanism also is recruited from the widespread endomycorrhizal symbiosis.

  5. Rhizobium strains differ considerably in outer membrane permeability and polymyxin B resistance.

    Science.gov (United States)

    Komaniecka, Iwona; Zamłyńska, Katarzyna; Zan, Radosław; Staszczak, Magdalena; Pawelec, Jarosław; Seta, Irena; Choma, Adam

    2016-01-01

    Six rhizobium (Rhizobium leguminosarum bv. Trifolii TA1, Sinorhizobium meliloti 1021, Mesorhizobium huakuii IFO 15243(T), Ochrobactrum lupini LUP 21(T), Bradyrhizobium japonicum USDA110 and B. elkanii USDA 76) and two Escherichia coli strains (E. coli ATCC 25922 and E. coli HB 101) were compared in respect to polymyxin B and EDTA resistance, as well as bacterial outer membrane (OM) permeability to a fluorescent hydrophobic agent (N-phenyl-1-naphthylamine - NPN). TEM (Transmission Electron Microscopy) and a microbial test demonstrated that all the rhizobia were much more resistant to polymyxin B in comparison with E. coli strains. EDTA and polymyxin B enhance permeability of B. japonicum and O. lupini OM. Other rhizobia incorporated NPN independently of the presence of membrane-deteriorating agents; however, the level of fluorescence (measured as NPN absorption) was strain dependent.

  6. Selection for cheating across disparate environments in the legume-rhizobium mutualism.

    Science.gov (United States)

    Porter, Stephanie S; Simms, Ellen L

    2014-09-01

    The primary dilemma in evolutionarily stable mutualisms is that natural selection for cheating could overwhelm selection for cooperation. Cheating need not entail parasitism; selection favours cheating as a quantitative trait whenever less-cooperative partners are more fit than more-cooperative partners. Mutualisms might be stabilised by mechanisms that direct benefits to more-cooperative individuals, which counter selection for cheating; however, empirical evidence that natural selection favours cheating in mutualisms is sparse. We measured selection on cheating in single-partner pairings of wild legume and rhizobium lineages, which prevented legume choice. Across contrasting environments, selection consistently favoured cheating by rhizobia, but did not favour legumes that provided less benefit to rhizobium partners. This is the first simultaneous measurement of selection on cheating across both host and symbiont lineages from a natural population. We empirically confirm selection for cheating as a source of antagonistic coevolutionary pressure in mutualism and a biological dilemma for models of cooperation.

  7. Construction of a marker system for the evaluation of competitiveness for legume nodulation in Rhizobium strains.

    Science.gov (United States)

    Sánchez-Cañizares, Carmen; Palacios, Jose

    2013-03-01

    A marker system has been set up for the analysis of competitiveness of Rhizobium leguminosarum strains for legume nodulation. The strains generated incorporate gusA and celB marker genes at identical positions and allow efficient scoring of single and double infections. Based on this system, we have found that strain UPM791 outcompetes 3841 for nodulation in pea. This technique will be useful to determine the effect of different traits on competitiveness.

  8. Requirement of succinate dehydrogenase activity for symbiotic bacteroid differentiation of Rhizobium meliloti in alfalfa nodules.

    OpenAIRE

    Gardiol, A E; Truchet, G L; Dazzo, F. B.

    1987-01-01

    Transmission electron microscopy was used to study the cellular morphologies of a wild-type Rhizobium meliloti strain (L5-30), a nitrogen fixation-ineffective (Fix-) succinate dehydrogenase mutant (Sdh-) strain, and a Fix+ Sdh+ revertant strain within alfalfa nodules and after free-living growth in a minimal medium containing 27 mM mannitol plus 20 mM succinate. The results showed a requirement of succinate dehydrogenase activity for symbiotic differentiation and maintenance of R. meliloti ba...

  9. Rhizobium (Agrobacterium) radiobacter Identified as a Cause of Chronic Endophthalmitis Subsequent to Cataract Extraction

    OpenAIRE

    Namdari, Hassan; Hamzavi, Sirus; Peairs, Randall R.

    2003-01-01

    Herein, we report a case of chronic endophthalmitis caused by a ceftazidime-resistant Rhizobium radiobacter strain in a 62-year-old male. The patient underwent an uneventful cataract extraction of the right eye a week prior to the appearance of symptoms (pain, redness, and blurring vision) which developed following a golf outing. Upon admission the patient received an emergency vitrectomy. The patient remained symptomatic, and R. radiobacter was isolated repeatedly from vitreous fluid culture...

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

    Science.gov (United States)

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

    2011-04-01

    Three aniline-degrading bacteria, strains DN316(T), DN316-1 and DN365, were isolated from activated sludge. According to 16S rRNA gene sequence-based phylogenetic analysis, the isolates belonged to the genus Rhizobium, with Rhizobium ( = Agrobacterium) radiobacter LMG 140(T) as the closest relative, with 96.5 % sequence similarity. Phylogenetic analysis of the representative strain DN316(T) using sequences of the glnA, thrC and recA genes and the 16S-23S intergenic spacer region confirmed the phylogenetic arrangement obtained from analysis of the 16S rRNA gene. DNA-DNA relatedness between DN316(T) and R. radiobacter LMG 140(T) was 43.7 %, clearly indicating that the representative strain DN316(T) represents a novel species. Phenotypic and biochemical characterization of the isolates and insertion sequence-PCR fingerprinting patterns showed several distinctive features that differentiated them from closely related species. The major components of the cellular fatty acids were C(18 : 1)ω7c (57.10 %), C(16 : 0) (11.31 %) and C(19 : 0) cyclo ω8c (10.13 %). Based on our taxonomic analysis, the three isolates from activated sludge represent a novel species of the genus Rhizobium, for which the name Rhizobium borbori sp. nov. is proposed. The type strain is DN316(T) ( = CICC 10378(T)  = LMG 23925(T)).

  11. Transmissible Resistance to Penicillin G, Neomycin, and Chloramphenicol in Rhizobium japonicum1

    Science.gov (United States)

    Cole, Michael A.; Elkan, Gerald H.

    1973-01-01

    The genetic basis for resistance to a number of antibiotics was examined in Rhizobium japonicum. Resistance to penicillin G, neomycin, and chloramphenicol appears to be mediated by an extrachromosomal element similar to that found in the Enterobacteriaceae. Resistance to these antibiotics was eliminated from cells by treatment with acridine orange, and resistance to all three antibiotics could be transferred en bloc to Agrobacterium tumefaciens under conditions excluding transformation or transduction as possible genetic mechanisms. PMID:4491197

  12. Rhizobium giardinii is the microsymbiont of Illinois bundleflower (Desmanthus illinoensis (Michx.) Macmillan) in midwestern prairies.

    Science.gov (United States)

    Beyhaut, Elena; Tlusty, Becki; van Berkum, Peter; Graham, Peter H

    2006-09-01

    Illinois bundleflower (Desmanthus illinoensis (Michx.) Macmillan) has potential as a grain and forage legume for the American Midwest. Inoculant-quality rhizobia for this legume have been identified but not previously characterized. Rhizobia trapped from 20 soils in the natural range of the Illinois bundleflower had characteristics that placed them overwhelmingly within the species Rhizobium giardinii, one of the few occasions this species has been recovered from legumes, raising questions on the biogeography and spread of midwestern prairie rhizobia.

  13. Rhizobium flavum sp. nov., a triazophos-degrading bacterium isolated from soil under the long-term application of triazophos.

    Science.gov (United States)

    Gu, Tao; Sun, Li Na; Zhang, Jun; Sui, Xin Hua; Li, Shun Peng

    2014-06-01

    A Gram-stain-negative, non-motile, pale yellow, rod-shaped bacterial strain, YW14(T), was isolated from soil and its taxonomic position was investigated by a polyphasic study. Strain YW14(T) did not form nodules on three different legumes, and the nodD and nifH genes were not detected by PCR. Strain YW14(T) contained Q-10 as the predominant ubiquinone. The major cellular fatty acid was C(18 : 1)ω7c. Phylogenetic analyses based on 16S rRNA gene sequences and seven housekeeping gene sequences (recA, atpD, glnII, gyrB, rpoB, dnaK and thrC) showed that strain YW14(T) belonged to the genus Rhizobium. Strain YW14(T) showed 16S rRNA gene sequence similarity of 93.4-97.3% to the type strains of recognized species of the genus Rhizobium. DNA-DNA relatedness between strain YW14(T) and the type strains of Rhizobium sullae IS123(T) and Rhizobium yanglingense CCBAU 71623(T) was 19.6-25.7%, indicating that strain YW14(T) was distinct from them genetically. Strain YW14(T) could also be differentiated from these phylogenetically related species of the genus Rhizobium by various phenotypic properties. On the basis of phenotypic properties, phylogenetic distinctiveness and genetic data, strain YW14(T) is considered to represent a novel species of the genus Rhizobium, for which the name Rhizobium flavum sp. nov. is proposed. The type strain is YW14(T) ( = KACC 17222(T) = CCTCC AB2013042(T)).

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

    Directory of Open Access Journals (Sweden)

    Erneste HAVUGIMANA

    2016-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Smadar Peleg-Grossman

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

  16. Rhizobium anhuiense as the predominant microsymbionts of Lathyrus maritimus along the Shandong Peninsula seashore line.

    Science.gov (United States)

    Li, Yan; Wang, En Tao; Liu, Yajing; Li, Xiangyue; Yu, Bing; Ren, Chenggang; Liu, Wei; Li, Yunzhao; Xie, Zhihong

    2016-09-01

    Beach pea [Lathyrus maritimus Bigelow, or Lathyrus japonicus subsp. maritimus (L.) P.W. Ball] is a wild legume distributed on the seashore line, and the rhizobia nodulating with this plant have been reported only rarely. In order to reveal the diversity of beach pea rhizobia on the seashore line of Shandong Peninsula, China, a total of 124 bacterial strains were isolated from the root nodules of beach pea plants collected from five sites. All the isolates were divided into five recA types after screening by recA gene sequence analysis and they consisted of Rhizobium anhuiense covering 122 symbiotic isolates in three recA types, as well as two single isolates Rhizobium sp. and Rhizobium lusitanum representing distinct recA types. The recA genotype III of R. anhuiense (103 isolates) represented by strain YIC11270 was dominant at all five sampling sites. Identical symbiotic genes (nodC and nifH) were detected in the three recA genotypes of R. anhuiense isolates that were closely related to those of the pea and faba rhizobia. This study clarified that R. anhuiense was the main symbiont for beach pea rhizobia on the seashore line of Shandong Peninsula. The low level genetic diversity of beach pea rhizobia revealed by both MLSA and the symbiotic genes might be related to the strong selection pressure produced by the saline-alkaline environment and the host plants.

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

    Science.gov (United States)

    Huang, Yu Chu; Fan, Ruimei; Grusak, Michael A; Sherrier, Janine D; Huang, C P

    2014-11-01

    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 impacted its development by decreasing the number of the first- and the second-order lateral roots, stem length, leaf surface area, and transpiration. The effect of nZnO dissolution on phytotoxicity was also examined. Results showed that Zn(2+) had negative impact on plant development. Exposure of R. leguminosarum bv. viciae 3841 to nZnO brought about morphological changes by rendering the microbial cells toward round shape and damaging the bacterial surface. Furthermore, the presence of nZnO in the rhizosphere affected root nodulation, delayed the onset of nitrogen fixation, and caused early senescence of nodules. Attachment of nanoparticles on the root surface and dissolution of Zn(2+) are important factors affecting the phytotocity of nZnO. Hence, the presence of nZnO in the environment is potentially hazardous to the Rhizobium-legume symbiosis system.

  18. Coexistence of Burkholderia, Cupriavidus, and Rhizobium sp. nodule bacteria on two Mimosa spp. in Costa Rica.

    Science.gov (United States)

    Barrett, Craig F; Parker, Matthew A

    2006-02-01

    rRNA gene sequencing and PCR assays indicated that 215 isolates of root nodule bacteria from two Mimosa species at three sites in Costa Rica belonged to the genera Burkholderia, Cupriavidus, and Rhizobium. This is the first report of Cupriavidus sp. nodule symbionts for Mimosa populations within their native geographic range in the neotropics. Burkholderia spp. predominated among samples from Mimosa pigra (86% of isolates), while there was a more even distribution of Cupriavidus, Burkholderia, and Rhizobium spp. on Mimosa pudica (38, 37, and 25% of isolates, respectively). All Cupriavidus and Burkholderia genotypes tested formed root nodules and fixed nitrogen on both M. pigra and M. pudica, and sequencing of rRNA genes in strains reisolated from nodules verified identity with inoculant strains. Inoculation tests further indicated that both Cupriavidus and Burkholderia spp. resulted in significantly higher plant growth and nodule nitrogenase activity (as measured by acetylene reduction assays) relative to plant performance with strains of Rhizobium. Given the prevalence of Burkholderia and Cupriavidus spp. on these Mimosa legumes and the widespread distribution of these plants both within and outside the neotropics, it is likely that both beta-proteobacterial genera are more ubiquitous as root nodule symbionts than previously believed.

  19. DEVELOPMENT OF PIGEON PEA INOCULATED WITH RHIZOBIUM ISOLATED FROM COWPEA TRAP HOST PLANTS

    Directory of Open Access Journals (Sweden)

    SALOMÃO LIMA GUIMARÃES

    2016-01-01

    Full Text Available Pigeon pea is an important protein source grown in several tropical and sub - tropical countries, and is considered a multi - purpose plant that is resistant to the conditions of the Brazilian Cerrado. Among the possible uses for cowpea, its use as a green manure, increasing soil nitrogen content through the association with diazotrophic bacteria, generically known as rhizobia, is noteworthy. The present work aimed to evaluate the efficiency of Rhizobium strains isolated from cowpea plants in the development of pigeon peas cultured in Red Latosol. The experiment was conducted in a greenhouse, using a completely randomized design with seven treatments and four replications. Treatments consisted of inoculation with four Rhizobium strains (MT8, MT15, MT16, and MT23 and one commercial inoculant comprising Bradyrhizobium spp. strains BR 2801 and BR 2003. There were two controls, one absolute (without inoculation or nitrogen fertilization and the other with nitrogen fertilization. Each experimental plot consisted of an 8 - dm 3 vase containing three plants. Analyzed variables included plant height, SPAD index, number and dry weight of nodules, and shoot and root dry masses. Pigeon peas responded significantly to inoculation treatment, since all the plants inoculated with Rhizobium strains isolated from cowpea strains showed results similar to plants in the nitrogen control and commercial inoculant treatments. This demonstrates a favorable plant – bacteria interaction, which can be utilized as an alternative nitrogen source for pigeon peas.

  20. Et evalueringseksperiment

    DEFF Research Database (Denmark)

    Christensen, Torben Spanget

    2008-01-01

    Artiklen præsenterer et evalueringseksperiment foretaget i 8 klasserum. Der er tale om mundtlige formative evalueringer som har fokus på elevernes faglige viden. Artiklen præsenterer en model for fagligt evaluerende lærer-elevsamtaler (FE-samtaler) som er udviklet i eksperimentet og resultaterne af...

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

    Directory of Open Access Journals (Sweden)

    Antonio Roberto Giardini

    1984-01-01

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

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

    Directory of Open Access Journals (Sweden)

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

    2012-05-01

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

  3. Synergism of VAM and Rhizobium on production and metabolism of IAA in roots and root nodules of Vigna mungo.

    Science.gov (United States)

    Chakrabarti, Jayanta; Chatterjee, Sabyasachi; Ghosh, Sisir; Chatterjee, Narayan Chandra; Dutta, Sikha

    2010-09-01

    Mature and healthy root nodules of Vigna mungo appeared to contain higher amount of indole-acetic acid (IAA) than non-nodulated roots. Dual effect of VAM fungus, Glomus fasciculatum and the nitrogen-fixing bacteria, Rhizobium sp. on the nodulation of roots of V. mungo was studied. It was recorded that the roots which were inoculated simultaneously with both the symbionts i.e., G. fasciculatum and Rhizobium exhibited greater amount of IAA production than the non-inoculated roots. A tryptophan pool present in the mature nodules and young leaves might serve as a precursor for IAA production in the roots and in the nodules. Activity of IAA-metabolizing enzymes, such as IAA oxidase, peroxidase, and polyphenol oxidase was investigated which indicates the active metabolism of IAA in roots and nodules. The Rhizobium symbiont isolated from fresh nodules of V. mungo produced significant amount of IAA under in vitro condition when tryptophan was added to the medium as precursor. Present study represents some beneficial effects of Rhizobium and G. fasciculatum on the production and metabolism of IAA in roots and nodules of V. mungo. The important physiological implication of the study on IAA production and its metabolism in Rhizobium-Legume-VAM tripartite symbiosis is certainly representing a new approach to satisfy the hormonal balance in the host plant.

  4. Et hjem

    DEFF Research Database (Denmark)

    Bruun, Maja Hojer

    2014-01-01

    Når folk sætter deres hjem til salg - især når der hersker usikkerhed om værdier og priser som under de seneste års boligkrise - får det os til at tænke over, hvad vilkårene er for at stifte, skabe og genskabe hjem i et moderne markedsbaseret samfund: Den integrerede helhed af personer, ting og s...

  5. 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.

    Science.gov (United States)

    Mehry, Askary; Akbar, Mostajeran; Giti, Emtiazi

    2008-06-15

    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 1.67 x 10(5) to 22 x 10(5) cfu g(-1) FW for Baccras cv. and 3.67 x 10(5) to 26 x 10(5) 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 0.67 x 10(5) to 21 x 10(5) cfu g(-1) FW for Baccross cv. and 0.33 x 10(5) to 18 x 10(5) 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

  6. Symbiotic plasmid is required for NolR to fully repress nodulation genes in Rhizobium leguminosarum A34

    Institute of Scientific and Technical Information of China (English)

    Fengqing Li; Bihe Hou; Guofan Hong

    2008-01-01

    NolR is a reguiator of noduiation genes present in Rhizobium and Sinorhizobium. However, the mechanism by which NolR participates in the inducible transcription ofnoduiation genes remains unclear. To investigate whether there are other factors regulating the function of NoIR, an insertion mutant of NolR in Rhizobium leguminosarum strain 8401, which lacks the symbiotic plasmid, was constructed by homologous recombination. We investigated the effects of NolR inactivation on the expression of nodulation genes. Three inducible nodulation genes (nodA, nodF and nodM) were expressed constitutively in NoiR-mutant, MRl14. Our results suggested that the symbiotic plasmid is required for NolR to fully repress nodulation genes in Rhizobium ieguminosarum A34. In addition, MRl14 has provided a useful tool for further study of molecular interactions between NolR and other factors.

  7. Inoculation of the nonlegume Capsicum annuum (L.) with Rhizobium strains. 1. Effect on bioactive compounds, antioxidant activity, and fruit ripeness.

    Science.gov (United States)

    Silva, Luís R; Azevedo, Jessica; Pereira, Maria J; Carro, Lorena; Velazquez, Encarna; Peix, Alvaro; Valentão, Patrícia; Andrade, Paula B

    2014-01-22

    Pepper (Capsicum annuum L.) is an economically important agricultural crop and an excellent dietary source of natural colors and antioxidant compounds. The levels of these compounds can vary according to agricultural practices, like inoculation with plant growth-promoting rhizobacteria. In this work we evaluated for the first time the effect of the inoculation of two Rhizobium strains on C. annuum metabolites and bioactivity. The results revealed a decrease of organic acids and no effect on phenolics and capsaicinoids of leaves from inoculated plants. In the fruits from inoculated plants organic acids and phenolic compounds decreased, showing that fruits from inoculated plants present a higher ripeness stage than those from uninoculated ones. In general, the inoculation with Rhizobium did not improve the antioxidant activity of pepper fruits and leaves. Considering the positive effect on fruit ripening, the inoculation of C. annuum with Rhizobium is a beneficious agricultural practice for this nonlegume.

  8. Molecular and culture dependent characterization of endolithic bacteria in two beach sand samples and description of Rhizobium endolithicum sp. nov.

    Science.gov (United States)

    Parag, B; Sasikala, Ch; Ramana, Ch V

    2013-12-01

    Endolithic metagenome analysis of two beach samples collected form Chilika, Odisha, India indicated rich bacterial diversity. While the metagenome analysis of sample one yielded 16S rRNA gene sequences which represent six phyla and 16 genera, sample two yielded very rich diversity representing 17 phyla and 286 genera. Six species of bacteria were isolated from the endolithic enrichments and most of them have 16S rRNA gene sequence similarity of >99 % with known taxa, except for strain JC140(T) having Rhizobium yanglingense SH22623(T) (96.8 %), R. alkalisoli CCBAU 01393(T) (96.3 %), R. vignae CCBAU 05176(T) (96.2 %), R. mesosinicum CCBAU 25010(T) (96.1 %) and other members of the genus Rhizobium with Rhizobium for which, the name R. endolithicum sp. nov. is proposed. The type strain is JC140(T) (= KCTC32077(T) = CCUG64352(T) = MTCC11723(T) = HAMBI 2447(T)).

  9. Rhizobium albus sp. nov., Isolated from Lake Water in Xiamen, Fujian Province of China.

    Science.gov (United States)

    Li, Yi; Lei, Xueqian; Xu, Yanting; Zhu, Hong; Xu, Meiying; Fu, Lijun; Zheng, Wei; Zhang, Jinli; Zheng, Tianling

    2017-01-01

    A Gram-stain-negative, aerobic bacterial strain, designated Y21(T), was isolated from surface lake water in Xiamen, Fujian Province of China. Growth was observed at temperatures from 4 to 37 °C, at salinities from 0 to 7.0 % and at pH from 6.0 to 10.0. Optimum growth was observed at 28 °C, at pH 7.0 and with 1.5-2.0 % (w/v) NaCl. The highest similarity of 16S rRNA gene sequence between strain Y21(T) and the other strains was 96.9 %. Phylogenetic analysis based on 16S rRNA gene sequencing revealed that the strain was a member of the genus Rhizobium, forming a distinct lineage with R. subbaraonis KCTC 23614(T). The dominant fatty acids were summed feature 8 (comprising C18:1 ω7c and/or C18:1 ω6c), C18:1 ω7c 11-methyl, which accounted for 78.1 %. The G+C content of the chromosomal DNA was 60.9 mol%. The predominant respiratory quinone was ubiquinone-10. The polar lipids of strain Y21(T) were found to consist of five unidentified phospholipids and three unidentified aminolipids. According to its morphology, physiology, fatty acid composition and 16S rRNA sequence data, strain Y21(T) should be regarded as a new species of the genus Rhizobium, for which Rhizobium albus sp. nov. is proposed (type strain Y21(T) = MCCC 1F01210(T) = KCTC 42252(T)).

  10. Rhizobium hidalgonense sp. nov., a nodule endophytic bacterium of Phaseolus vulgaris in acid soil.

    Science.gov (United States)

    Yan, Jun; Yan, Hui; Liu, Li Xue; Chen, Wen Feng; Zhang, Xiao Xia; Verástegui-Valdés, Myrthala M; Wang, En Tao; Han, Xiao Zeng

    2017-01-01

    One Gram-negative, aerobic, motile, rod-shaped bacterium, designated as FH14(T), was isolated from nodules of Phaseolus vulgaris grown in Hidalgo State of Mexico. Results based upon 16S rRNA gene (≥99.8 % similarities to known species), concatenated sequence (recA, atpD and glnII) analysis of three housekeeping genes (≤93.4 % similarities to known species) and average nucleotide identity (ANI) values of genome sequence (ranged from 87.6 to 90.0 % to related species) indicated the distinct position of strain FH14(T) within the genus Rhizobium. In analyses of symbiotic genes, only nitrogen fixation gene nifH was amplified that had nucleotide sequence identical to those of the bean-nodulating strains in R. phaseoli and R. vallis, while nodulation gene nodC gene was not amplified. The failure of nodulation to its original host P. vulgaris and other legumes evidenced the loss of its nodulation capability. Strain FH14(T) contained summed feature 8 (C18:1 ω6c/C18:1 ω7c, 59.96 %), C16:0 (10.6 %) and summed feature 2 (C12:0 aldehyde/unknown 10.928, 10.24 %) as the major components of cellular fatty acids. Failure to utilize alaninamide, and utilizing L-alanine, L-asparagine and γ-amino butyric acid as carbon source, distinguished the strain FH14(T) from the type strains for the related species. The genome size and DNA G+C content of FH14(T) were 6.94 Mbp and 60.8 mol %, respectively. Based on those results, a novel specie in Rhizobium, named Rhizobium hidalgonense sp. nov., was proposed, with FH14(T) (=HAMBI 3636(T) = LMG 29288(T)) as the type strain.

  11. Production of nodulation factors by Rhizobium meliloti: fermentation, purification and characterization of glycolipids.

    Science.gov (United States)

    Kohring, B; Baier, R; Niehaus, K; Pühler, A; Flaschel, E

    1997-12-01

    Lipooligosaccharides, synthesized by soil bacteria of the genera Rhizobium, are known to have multifunctional effects on a wide variety of plants as signal substances in symbiosis initiation, cell response elicitation and growth regulation. These so called nodulation (Nod-) factors represent interesting biotechnological products with respect to fundamental studies of symbiotic interactions as well as for potential applications. Therefore, a batch fermentation process on a scale of 30 l has been developed by means of the Rhizobium meliloti strain R.m. 1021 (pEK327) strongly overexpressing the genes for the synthesis of Nod factors. Induction by the flavone luteolin led to growth associated production of the lipooligosaccharides. Ultrafiltration was used for separating the biomass from the filtrate containing the extracellular Nod factors. Simultaneously, ultrafiltration reduced the amount of lipophilic substances, which would otherwise interfere with processes downstream. The second separation step consisted in adsorption on XAD-2, a nonspecific hydrophobic adsorptive resin. Adsorption of Nod factors was carried out by batch operation of a stirred tank. Desorption was performed by elution with methanol in a fixed bed column. A semi-preparative reversed phase HPLC (Polygoprep 100-30 C18) was chosen as the final purification step. The Nod factors were obtained after evaporation and lyophilization. Thus, about 600 mg of Nod factors were produced from 20 l of fermentation broth. The Nod factors produced by Rhizobium meliloti R.m. 1021 (pEK327) were identified by liquid secondary ion mass spectrometry and by reversed-phase HPLC as fluorescent derivatives of 2-aminobenzamide. The biological activity of the products was demonstrated by means of the root hair deformation (HAD-) assay.

  12. Toxicity assessment of herbicides quizalafop-p-ethyl and clodinafop towards Rhizobium pea symbiosis.

    Science.gov (United States)

    Ahemad, Munees; Khan, Mohammad Saghir

    2009-06-01

    In modern conventional agriculture, herbicides are frequently used to prevent yield losses due to weeds. Herbicides also affect negatively the productivity of legumes. With these considerations, we evaluated the effects of soil applications of different concentrations of quizalafop-p-ethyl and clodinafop on the performance of Rhizobium inoculated pea, grown in clay pots. In this study, the concentration of herbicides higher than the recommended rates of quizalafop-p-ethyl and clodinafop adversely affected the dry matter accumulation, symbiotic properties, grain yield and nutrient status of pea plants. Toxicity of quizalafop-p-ethyl and clodinafop to pea plants increased progressively with increase in rates of herbicides. Of the two herbicides, quizalafop-p-ethyl was more toxic than clodinafop. In contrast, when herbicide tolerant Rhizobium strain MRP1 was also used with herbicide, it increased the measured parameters at all concentrations. A maximum increase of 11%, 17%, 46%, 33%, 21% and 7% in the root N, shoot N, root P, shoot P, seed yield and seed protein, respectively, was observed when MRP1 was used with 120 microg quizalafop-p-ethyl kg(-1) soil while with 1,200 microg clodinafop kg(-1) soil it increased the root N, shoot N, root P, shoot P, seed yield and seed protein by 20%, 9%, 56%, 56%, 29% and 7%, respectively, compared with the un-inoculated but herbicide treated control. This study suggested that the toxic effects of herbicides on pea plants could be attenuated by applying growth promoting herbicide tolerant strain of Rhizobium under herbicide stressed soil environment.

  13. Kinetics study of pyridine biodegradation by a novel bacterial strain, Rhizobium sp. NJUST18.

    Science.gov (United States)

    Shen, Jinyou; Zhang, Xin; Chen, Dan; Liu, Xiaodong; Zhang, Libin; Sun, Xiuyun; Li, Jiansheng; Bi, Huiping; Wang, Lianjun

    2014-06-01

    Biodegradation of pyridine by a novel bacterial strain, Rhizobium sp. NJUST18, was studied in batch experiments over a wide concentration range (from 100 to 1,000 mg l(-1)). Pyridine inhibited both growth of Rhizobium sp. NJUST18 and biodegradation of pyridine. The Haldane model could be fitted to the growth kinetics data well with the kinetic constants μ* = 0.1473 h(-1), K s = 793.97 mg l(-1), K i = 268.60 mg l(-1) and S m = 461.80 mg l(-1). The true μ max, calculated from μ*, was found to be 0.0332 h(-1). Yield coefficient Y X/S depended on S i and reached a maximum of 0.51 g g(-1) at S i of 600 mg l(-1). V max was calculated by fitting the pyridine consumption data with the Gompertz model. V max increased with initial pyridine concentration up to 14.809 mg l(-1) h(-1). The q S values, calculated from [Formula: see text], were fitted with the Haldane equation, yielding q Smax = 0.1212 g g(-1) h(-1) and q* = 0.3874 g g(-1) h(-1) at S m' = 507.83 mg l(-1), K s' = 558.03 mg l(-1), and K i' = 462.15 mg l(-1). Inhibition constants for growth and degradation rate value were in the same range. Compared with other pyridine degraders, μ max and S m obtained for Rhizobium sp. NJUST18 were relatively high. High K i and K i' values and extremely high K s and K s' values indicated that NJUST18 was able to grow on pyridine within a wide concentration range, especially at relatively high concentrations.

  14. Physiological distinctions of pea symbiotic mutants with various nodulation level under inoculation by Rhizobium leguminosarum

    Directory of Open Access Journals (Sweden)

    Akimova G. P.

    2012-11-01

    Full Text Available The study was focused on morphological and physiological peculiarities of pea plants with various nodulation ability under the infection by Rhizobium leguminosarum. Microscopic studies identified distinct features in formation of root nodules in different pea mutants. We revealed differences in the content of indole-acetic acid (IAA in mutants in the root zones differing by sensibility to R. leguminosarum. It was concluded that hormonal system of plants plays an important role in control of nodulation process, and emergence of mutations inducing disturbance of nodule-forming ability apparently depends on root hormonal status, in particular, IAA concentration ensuring both formation of nodule meristem and further organogenesis of the nodule.

  15. A phosphate transport system is required for symbiotic nitrogen fixation by Rhizobium meliloti.

    OpenAIRE

    Bardin, S.; Dan, S.; Osteras, M.; Finan, T M

    1996-01-01

    The bacterium Rhizobium meliloti forms N2-fixing root nodules on alfalfa plants. The ndvF locus, located on the 1,700-kb pEXO megaplasmid of R. meliloti, is required for nodule invasion and N2 fixation. Here we report that ndvF contains four genes, phoCDET, which encode an ABC-type transport system for the uptake of Pi into the bacteria. The PhoC and PhoD proteins are homologous to the Escherichia coli phosphonate transport proteins PhnC and PhnD. The PhoT and PhoE proteins are homologous to ...

  16. Extracción de adn plasmidico de cepas de rhizobium leguminosarum

    Directory of Open Access Journals (Sweden)

    M. Y, Cortés L.

    2010-07-01

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

  17. Extracción de adn plasmidico de cepas de rhizobium leguminosarum

    OpenAIRE

    2010-01-01

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

  18. Symbiotic Autoregulation of nifA Expression in Rhizobium leguminosarum bv. viciae

    OpenAIRE

    Martínez, Marta; Palacios, José M.; Imperial, Juan; Ruiz-Argüeso, Tomás

    2004-01-01

    NifA is the general transcriptional activator of nitrogen fixation genes in diazotrophic bacteria. In Rhizobium leguminosarum bv. viciae UPM791, the nifA gene is part of a gene cluster (orf71 orf79 fixW orf5 fixABCX nifAB) separated by 896 bp from an upstream and divergent truncated duplication of nifH (ΔnifH). Symbiotic expression analysis of genomic nifA::lacZ fusions revealed that in strain UPM791 nifA is expressed mainly from a σ54-dependent promoter (PnifA1) located upstream of orf71. Th...

  19. Rhizobium arenae sp. nov., isolated from the sand of Desert Mu Us, China.

    Science.gov (United States)

    Zhang, Shengnan; Yang, Shanshan; Chen, Wei; Chen, Yong; Zhang, Mingjuan; Zhou, Xinai; Fan, Guohua; Feng, Fu Ying

    2017-07-01

    A Gram-strain-negative, rod-shaped, motile bacterium, designated MIM27T, was isolated from the sand of the Mu Us Desert, PR China. The strain could grow at 4-45 °C (optimum, 37 °C), at pH 6.6-9.0 (optimum, 8.0) and in the presence of 0-3 % (w/v) NaCl (optimum, 0 % in RNA liquid medium). The results of phylogenetic analysis of 16S rRNA gene sequences indicated that the strain represented a member of the genus Rhizobium, with the highest similarity (96.5 %) to Rhizobium pakistanense BN-19T. The results of analysis of the sequences of the nitrogen fixation gene nifH and three housekeeping genes, recA, atpD and glnII, also indicated that MIM27T was most closely related to the species of the genus Rhizobiumwith validly published names but the similarities were low (≤90.7 %). MIM27T did not form nodules on Pisum sativum, Vicia faba, Astragalus sinicus and Phaseolus vulgaris. The major respiratory quinone of MIM27T was Q-10. The genomic DNA G+C content was 59.8 mol%. Major fatty acids of MIM27T were summed feature 8 (C18 : 1ω7c and/or C18 : 1ω6c), C18 : 1ω7c 11-methyl, C16 : 0, summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c) and summed feature 2 (C12 : 0 aldehyde and/or unknown ECL 10.9525). On the basis of the physiological, chemotaxonomic and phenotypic data, MIM27T is suggested to represent a novel species of the genus Rhizobium, for which the name Rhizobium arenae sp. nov. is proposed. The type strain is MIM27T (=KCTC 52299T=MCCC 1K03215T).

  20. Production and composition of extracellular polysaccharide synthesized by a Rhizobium isolate of Vigna mungo (L.) Hepper.

    Science.gov (United States)

    Mandal, Santi Mohan; Ray, Bimalendu; Dey, Satyahari; Pati, Bikas Ranjan

    2007-08-01

    An extracellular polysaccharide (EPS) was produced by a Rhizobium sp. isolated from the root nodules of Vigna mungo (L.) Hepper. Maximum EPS production (346 mg l(-1)) was when the yeast extract basal medium was supplemented with mannitol (1%), biotin (1.5 mg l(-1)) and asparagine (0.3%). Ribose (53%) and mannose (47%) were the principle monomers of the EPS. Chemical, chromatographic and spectroscopic analysis showed that this polymer, which has Man(4)Rib(1) as an oligomeric subunit, has an apparent molecular mass of 750 kDa.

  1. Rhizobium (Agrobacterium) radiobacter identified as a cause of chronic endophthalmitis subsequent to cataract extraction.

    Science.gov (United States)

    Namdari, Hassan; Hamzavi, Sirus; Peairs, Randall R

    2003-08-01

    Herein, we report a case of chronic endophthalmitis caused by a ceftazidime-resistant Rhizobium radiobacter strain in a 62-year-old male. The patient underwent an uneventful cataract extraction of the right eye a week prior to the appearance of symptoms (pain, redness, and blurring vision) which developed following a golf outing. Upon admission the patient received an emergency vitrectomy. The patient remained symptomatic, and R. radiobacter was isolated repeatedly from vitreous fluid cultures over a 5-month period. Ultimately, the infection responded to intravitreal gentamicin, oral ciprofloxacin, and removal of the lens implant.

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

    Directory of Open Access Journals (Sweden)

    Lingbo eMeng

    2015-05-01

    Full Text Available 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 µm 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 Glomus 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 mg, 7.01 mg and 11.45 mg more than that of G.m., SH212 and NI and similarly, 6.40 mg, 7.58 mg 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.

  3. Underexpression of Ap from R-Plasmids in Fast-Growing Rhizobium Species

    Science.gov (United States)

    Sikka, Virendra K.; Kumar, Sushil

    1984-01-01

    The presence of the plasmid RP1 in the cells of Rhizobium leguminosarum strains Rld1, 300, and 248, R. phaseoli 1233, R. trifolii strains T1 and 6661, and R. meliloti 4013 was found to appreciably increase bacterial resistance toward kanamycin and tetracycline but not toward ampicillin. The presence of 16 other R-plasmids in R. leguminosarum was also found to either not increase or only marginally increase bacterial resistance toward ampicillin. It appears now that underexpression of the plasmid-specified ampicillin function is common to most fast- and slow-growing rhizobia. PMID:16346686

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

    Science.gov (United States)

    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 glutamine synthetase-glutamate synthase pathway preferentially nodulated Phaseolus vulgaris. PMID:2892830

  5. 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.

  6. 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 μm) 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

  7. Effects of Rhizobium inoculation, organic and chemical fertilizers on yield and physical properties of faba bean seeds.

    Science.gov (United States)

    Elsheikh, E A; Elzidany, A A

    1997-01-01

    A field experiment was carried out to investigate the effect of Rhizobium inoculation, sulphur, nitrogen and chicken manure on yield, 100-seed weight, cookability, non-soakers, total defects and hydration coefficient of faba bean. The results showed that sulphur, nitrogen and chicken manure treatments significantly (p < or = 0.05) increased yield, 100-seed weight, non-soakers, and hydration coefficient, in the absence of Rhizobium inoculation. The results also showed that Rhizobium inoculation significantly (p < or = 0.05) increased yield, 100-seed weight, cookability, but decreased non-soakers. A positive correlation (r = 0.90) was observed between the non-soaker percent and the total defect percent. No correlation was found between non-soakers, hydration coefficient and cookability. The results of this investigation indicate that Rhizobium inoculation is a promising fertilizer because it is cheap, easy to handle and improves plant growth and seed quality. The efficiency of inoculation could be improved with the addition of biological, chemical or organic fertilizers. Generally, fertilization of faba bean with nitrogen, sulphur or chicken manure not only increased plant growth and yield, but also improved seed quality and nutritional value.

  8. 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…

  9. Rhizobium qilianshanense sp. nov., a novel species isolated from root nodule of Oxytropis ochrocephala Bunge in China.

    Science.gov (United States)

    Xu, Lin; Zhang, Yong; Deng, Zheng Shan; Zhao, Liang; Wei, Xiu Li; Wei, Ge Hong

    2013-03-01

    During a study of the diversity and phylogeny of rhizobia isolated from root nodules of Oxytropis ochrocephala grown in the northwest of China, four strains were classified in the genus Rhizobium on the basis of their 16S rRNA gene sequences. These strains have identical 16S rRNA gene sequences, which showed a mean similarity of 94.4 % with the most closely related species, Rhizobium oryzae. Analysis of recA and glnA sequences showed that these strains have less than 88.1 and 88.7 % similarity with the defined species of Rhizobium, respectively. The genetic diversity revealed by ERIC-PCR fingerprinting indicated that the isolates correspond to different strains. Strain CCNWQLS01(T) contains Q-10 as the predominant ubiquinone. The major fatty acids were identified as feature 8 (C18: 1ω7c and/or C18: 1ω6c; 67.2 %). Therefore, a novel species Rhizobium qilianshanense sp. nov. is proposed, and CCNWQLS01(T) (= ACCC 05747(T) = JCM 18337(T)) is designated as the type strain.

  10. A Rhizobium leguminosarum CHDL- (Cadherin-Like-) Lectin Participates in Assembly and Remodeling of the Biofilm Matrix

    DEFF Research Database (Denmark)

    Vozza, Nicolás F.; Abdian, Patricia L; Russo, Daniela M

    2016-01-01

    important advances were made in the identification of the genetic and extracellular factors required for biofilm formation, the mechanisms leading to biofilm matrix assembly, and the roles of extracellular proteins in these processes are still poorly understood. The symbiont Rhizobium leguminosarum requires...

  11. Rhizobium hedysari sp. nov., a novel species isolated from a root nodule of Hedysarum multijugum in China.

    Science.gov (United States)

    Xu, Lin; Shi, Jianfeng; Li, Caixia; Zhu, Shengan; Li, Bo

    2017-04-01

    A strain 5-1-2(T) was isolated from a root nodule of Hedysarum multijugum collected from Zhangye city, Gansu province, north-west China. Phylogenetic analysis based on the 16S rRNA gene sequence and other housekeeping genes (recA and atpD) indicated that the strain represents a novel species in the genus Rhizobium close to the strain Rhizobium subbaraonis JC85(T) with similarities of 98.27, 88.92 and 89.62%, respectively. Strain 5-1-2(T) contained Q-10 as the predominant ubiquinone. Our results showed that the major fatty acids were feature 8 (C18:1 ω7c and/or C18:1 ω6c; 38.90%). In addition, the DNA-DNA hybridizations with the type strains R. subbaraonis JC85(T) and Rhizobium halophytocola YC6881(T) were 39.2 ± 2.1 and 44.3 ± 1.9, respectively. Therefore, a novel species Rhizobium hedysari sp. nov. is proposed, and 5-1-2(T) (=CGMCC1.15677(T) = NBRC112532(T)) is designated as the type strain.

  12. Rhizobium leguminosarum exoB mutants are deficient in the synthesis of UDP-glucose 4'-epimerase

    NARCIS (Netherlands)

    CREMERS, HCJC; Batley, M; Redmond, J W; Eijdems, Elisabeth; BREEDVELD, MW; ZEVENHUIZEN, LPTM; Pees, Elisabeth; Wijffelman, C A; Lugtenberg, Ben J.J.

    1990-01-01

    Rhizobium leguminosarum bv. viciae Exo- mutant strains RBL5523,exo7::Tn5,RBL5523,exo8::Tn5 and RBL5523,exo52::Tn5 are affected in nodulation and in the syntheses of lipopolysaccharide, capsular polysaccharide, and exocellular polysaccharide. These mutants were complemented for nodulation and for the

  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. Transfer and loss of naturally-occuring plasmids among isolates of Rhizobium leguminosarum bv. viciae in heavy metal contaminated soils

    NARCIS (Netherlands)

    Lakzian, A.; Murphy, P.J.; Giller, K.E.

    2007-01-01

    Plasmid transfer among isolates of Rhizobium leguminosarum bv. viciae in heavy metal contaminated soils from a long-term experiment in Braunschweig, Germany, was investigated under laboratory conditions. Three replicate samples each of four sterilized soils with total Zn contents of 54, 104, 208 and

  15. Rhizobium leguminosarum bv. viciae populations in soils with increasing heavy metal contamination: abundance, plasmid profiles, diversity and metal tolerance

    NARCIS (Netherlands)

    Lakzian, A.; Murphy, P.; Turner, A.; Beynon, J.L.; Giller, K.E.

    2002-01-01

    Populations of Rhizobium leguminosarum bv. viciae were investigated from plots of a long-term sewage sludge experiment in Braunschweig, Germany, which represented a gradient of increasing metal contamination. The number of R. leguminosarum bv. viciae decreased from 105 cells g¿1 soil in uncontaminat

  16. A paradigm for endosymbiotic life: cell differentiation of Rhizobium bacteria provoked by host plant factors.

    Science.gov (United States)

    Kondorosi, Eva; Mergaert, Peter; Kereszt, Attila

    2013-01-01

    Symbiosis between Rhizobium bacteria and legumes leads to the formation of the root nodule. The endosymbiotic bacteria reside in polyploid host cells as membrane-surrounded vesicles where they reduce atmospheric nitrogen to support plant growth by supplying ammonia in exchange for carbon sources and energy. The morphology and physiology of endosymbionts, despite their common function, are highly divergent in different hosts. In galegoid plants, the endosymbionts are terminally differentiated, uncultivable polyploid cells, with remarkably elongated and even branched Y-shaped cells. Bacteroid differentiation is controlled by host peptides, many of which have antibacterial activity and require the bacterial function of BacA. Although the precise and combined action of several hundred host peptides and BacA has yet to be discovered, similarities, especially to certain insect-bacterium symbioses involving likewise host peptides for manipulation of endosymbionts, suggest convergent evolution. Rhizobium-legume symbiosis provides a rich source of information for understanding host-controlled endosymbiotic life in eukaryotic cells.

  17. 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.

  18. Production of proteasome inhibitor syringolin A by the endophyte Rhizobium sp. strain AP16.

    Science.gov (United States)

    Dudnik, Alexey; Bigler, Laurent; Dudler, Robert

    2014-06-01

    Syringolin A, the product of a mixed nonribosomal peptide synthetase/polyketide synthase encoded by the syl gene cluster, is a virulence factor secreted by certain Pseudomonas syringae strains. Together with the glidobactins produced by a number of beta- and gammaproteobacterial human and animal pathogens, it belongs to the syrbactins, a structurally novel class of proteasome inhibitors. In plants, proteasome inhibition by syringolin A-producing P. syringae strains leads to the suppression of host defense pathways requiring proteasome activity, such as the ones mediated by salicylic acid and jasmonic acid. Here we report the discovery of a syl-like gene cluster with some unusual features in the alphaproteobacterial endophyte Rhizobium sp. strain AP16 that encodes a putative syringolin A-like synthetase whose components share 55% to 65% sequence identity (72% to 79% similarity) at the amino acid level. As revealed by average nucleotide identity (ANI) calculations, this strain likely belongs to the same species as biocontrol strain R. rhizogenes K84 (formely known as Agrobacterium radiobacter K84), which, however, carries a nonfunctional deletion remnant of the syl-like gene cluster. Here we present a functional analysis of the syl-like gene cluster of Rhizobium sp. strain AP16 and demonstrate that this endophyte synthesizes syringolin A and some related minor variants, suggesting that proteasome inhibition by syrbactin production can be important not only for pathogens but also for endophytic bacteria in the interaction with their hosts.

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

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    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.

  20. Symbiont shift towards Rhizobium nodulation in a group of phylogenetically related Phaseolus species.

    Science.gov (United States)

    Servín-Garcidueñas, Luis E; Zayas-Del Moral, Alejandra; Ormeño-Orrillo, Ernesto; Rogel, Marco A; Delgado-Salinas, Alfonso; Sánchez, Federico; Martínez-Romero, Esperanza

    2014-10-01

    Bean plants from the Phaseolus genus are widely consumed and represent a nitrogen source for human nutrition. They provide biological fertilization by establishing root nodule symbiosis with nitrogen-fixing bacteria. To establish a successful interaction, bean plants and their symbiotic bacteria need to synchronize a proper molecular crosstalk. Within the Phaseolus genus, P. vulgaris has been the prominent species to study nodulation with Rhizobium symbionts. However the Phaseolus genus comprises diverse species whose symbionts have not been analyzed. Here we identified and studied nodule bacteria from representative Phaseolus species not previously analyzed and from all the described wild species related to P. vulgaris. We found Bradyrhizobium in nodules from most species representing all Phaseolus clades except in five phylogenetically related species from the P. vulgaris clade. Therefore we propose that Bradyrhizobium nodulation is common in Phaseolus and that there was a symbiont preference shift to Rhizobium nodulation in few related species. This work sets the basis to further study the genetic basis of this symbiont substitution.

  1. Phenotypic and molecular characterization of Rhizobium vitis strains from vineyards in Turkey

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    Didem CANIK OREL

    2016-05-01

    Full Text Available Crown gall-affected grapevine samples were collected during 2009–2010 from major vineyards, located in different Turkish provinces. One hundred and three bacterial strains were obtained from 88 vineyards and 18 grapevine varieties; they were tumorigenic when inoculated in tobacco, sunflower and Datura stramonium plants and were identified as Rhizobium vitis using biochemical and physiological tests as well as PCR and specific primers. Nineteen R. vitis strains presented a number of anomalous biochemical and physiological characters. PCR and opine-specific primers revealed the presence of octopine/cucumopine-type plasmid in 82 R. vitis strains, nopaline-type plasmids in 18 strains and vitopine-type plasmids in three strains. Clonal relationship of strains was determined using Pulsed Field Gel Electrophoresis following digestion of genomic DNA with the restriction endonuclease PmeI. The greatest genetic diversity was found for the strains from Denizli, Ankara and Nevşehir provinces. Nopaline and vitopine-types of Rhizobium vitis were detected for the first time in Turkey.

  2. Mimosine Content of Leucaena leucocephala and the Sensitivity of Rhizobium to Mimosine.

    Science.gov (United States)

    Mathews, A; Vittal Rai, P

    1985-01-01

    Mimosine was qualitatively and quantitatively estimated from the different parts of Leucaena leucocephala strains K-8 and K-67. The amount of mimosine as percentage of dry weight in the two strains were, respectively, as follows: seeds, 6.82, 9.98; old leaves, 1.5, 1.33; young leaves, 2.85, 3.33; main root, 1.13, 1.02; lateral roots, 1.46, 1.17; stems, 0.73, 0.33. Rhizobium isolates from L. leucocephala (UAS-Ll-8, UAS-Ll-67), Mimosa pudica (UAS-Mp) and Prosopis juliflora (UAS-Pj) formed an effective (nod(+) fix(+)) association with Leucaena, while an isolate from Crotalaria sp. (UAS-Cr) proved to be ineffective (nod(+) fix(-)). All isolates performed better than reference strain TAL-82. Strain UAS-Pj gave optimum nodulation and plant growth characteristics. The effect of mimosine on the vegetative Rhizobium cultures was studied by the lawn method of growing rhizobia, using 2.5 to 15 mg·ml(-1) mimosine. All the effective strains were stimulated by mimosine up to 7.5 mg·ml(-1)strains. UAS-Ll-8 and UAS-Ll-67 were stimulated up to 15 mg·ml(-1) of mimosine. The ineffective strain UAS-Cr was inhibited at all the concentrations of mimosine tried.

  3. Production of Proteasome Inhibitor Syringolin A by the Endophyte Rhizobium sp. Strain AP16

    Science.gov (United States)

    Bigler, Laurent; Dudler, Robert

    2014-01-01

    Syringolin A, the product of a mixed nonribosomal peptide synthetase/polyketide synthase encoded by the syl gene cluster, is a virulence factor secreted by certain Pseudomonas syringae strains. Together with the glidobactins produced by a number of beta- and gammaproteobacterial human and animal pathogens, it belongs to the syrbactins, a structurally novel class of proteasome inhibitors. In plants, proteasome inhibition by syringolin A-producing P. syringae strains leads to the suppression of host defense pathways requiring proteasome activity, such as the ones mediated by salicylic acid and jasmonic acid. Here we report the discovery of a syl-like gene cluster with some unusual features in the alphaproteobacterial endophyte Rhizobium sp. strain AP16 that encodes a putative syringolin A-like synthetase whose components share 55% to 65% sequence identity (72% to 79% similarity) at the amino acid level. As revealed by average nucleotide identity (ANI) calculations, this strain likely belongs to the same species as biocontrol strain R. rhizogenes K84 (formely known as Agrobacterium radiobacter K84), which, however, carries a nonfunctional deletion remnant of the syl-like gene cluster. Here we present a functional analysis of the syl-like gene cluster of Rhizobium sp. strain AP16 and demonstrate that this endophyte synthesizes syringolin A and some related minor variants, suggesting that proteasome inhibition by syrbactin production can be important not only for pathogens but also for endophytic bacteria in the interaction with their hosts. PMID:24727275

  4. Synergism Among VA Mycorrhiza, Phosphate Solubilizing Bacteria and Rhizobium for Symbiosis with Blackgram (Vigna mungo L.) UnderField Conditions

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A field experiment was conducted at the G.B. Pant University Research Station, Ujhani (U.P.) in rainy (Kharif) season of the year 1994-1995 to study the effect of Rhizobium, VAM (vesicular arbuscular mycorrhiza) and PSB (phosphate solubilizing bacteria) inoculation, with and without P, on blackgram (Vigna mungo L.) seed yield. Phosphorus application in soil with medium P content (5.4 mg kg1) increased nodulation, grain yield, N and P in plant and grain over no phosphorus control. Forty kilograms of P2O5 each hactare recorded an increase of 20.6 % in nodule dry weight, significant increases of 0.35 g kg-1 in N concentration and 1.28 g kg-1 in P concentration of plant over 20 kg P2O5 ha-1. Similar significant increases of 0.59 g kg-1 in grain yield and 0.54 and 0.23 g kg-1 in N and P concentrations of the grain, respectively, over 20 kg P2O5 ha-1 were also obtained with higher dose. Inoculation of Rhizobium + VAM + PSB at all the stages of plant growth recorded maximum increases in all the parameters studied. Dual inoculation of Rhizobium with either VAM or PSB was generally significant in the effect and better than that of VAM + PSB, however, P accumulation in plant and grain was more with VAM + PSB. Among single inoculations, Rhizobium gave highest and 21.0 % more nodule number, 34.7 % more nodule dry mass, 0.73 g kg-1 more N in grain and 4.2 % higher grain yield over PSB. PSB, however, registered significant increases in P concentration in plant and grain over VAM and Rhizobium.

  5. 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 (ANU843ΔC2 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 ANU843ΔC2 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.

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

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    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

  7. 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

    2015-01-01

    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.

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

    Science.gov (United States)

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

    2013-12-01

    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 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.

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

    Directory of Open Access Journals (Sweden)

    Maqshoof Ahmad

    2013-12-01

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

  10. Biochemical characterization of a novel L-asparaginase from Paenibacillus barengoltzii being suitable for acrylamide reduction in potato chips and mooncakes.

    Science.gov (United States)

    Shi, Ran; Liu, Yu; Mu, Qing; Jiang, Zhengqiang; Yang, Shaoqing

    2017-03-01

    A novel L-asparaginase gene (PbAsnase) from Paenibaeillus barengoltzii CAU904 was cloned and expressed in Escherichia coli. The L-asparaginase gene was 1011bp encoding 336 amino acids. Multiple sequence alignment of PbAsnase with other known L-asparaginases revealed that the enzyme showed high similarities with some Rhizobial-type L-asparaginases, sharing the highest identity of 32% with a characterized L-asparaginase from Rhizobium etli CFN 42, suggesting that it should be a novel L-asparaginase. The recombinant L-asparaginase (PbAsnase) was purified to homogeneity and biochemically characterized. The purified enzyme was optimally active at pH 8.5 and 45°C, respectively. It was stable within pH 5.5-10.0 and at temperatures below 55°C. PbAsnase exhibited strict substrate specificity towards L-asparagine (35.2U/mg), with Km and Vmax values of 3.6mM and 162.2μmol/min/mg, respectively, but displayed trace activity towards L-glutamine. Moreover, the application potential of PbAsnase on acrylamide migration in potato chips and mooncakes was evaluated. The pretreatment by PbAsnase significantly decreased the acrylamide contents in potato chips and mooncakes by 86% and 52%, respectively. The unique properties of PbAsnase may make it a good candidate in industries, especially in food safety. Copyright © 2016 Elsevier B.V. All rights reserved.

  11. Isolation and characterization of Rhizobium meliloti mutants affected in exopolysaccharide production.

    Science.gov (United States)

    Rodríguez-Navarro, D N; Palomares, A J; Casadesús, J

    1991-06-01

    Rhizobium meliloti mutants affected in the production of exopolysaccharide (EPS) were isolated after N-methyl-N'-nitro-N-nitrosoguanidine mutagenesis. The mutants were classified into three phenotypic classes: (I) Exo-, rough mutants lacking exopolysaccharide; (II) Exos (for "small") which form tiny, compact colonies and synthesize reduced amounts of EPS; and (III) Exoc (for "constitutive"), hypermucoid mutants which overproduce EPS. Hypermucoid strains showed increased resistance to desiccation. All the mutants were able to nodulate, although a significant decrease in infectivity degree and/or competitiveness was found in rough and compact strains. Two mutants proved to be deficient in nitrogen fixation. Complementation analysis with cloned R. meliloti exo genes could not be applied to the study of these Fix- mutants because introduction of plasmids derived from cosmid vector pLAFR1 caused loss of nodulating ability. However, complementation of calcofluor staining and EPS production was observed. Complementation with certain exo genes also caused a marked increase in motility.

  12. Regulation of symbiotic nitrogen fixation in root nodules of alfalfa (Medicago sativa) infected with Rhizobium meliloti.

    Science.gov (United States)

    Kamberger, W

    1977-10-24

    Symbiotic nitrogen fixation of Rhizobium meliloti bacteroids in Medicago sativa root nodules was suppressed by several inorganic nitrogen sources. Amino acids like glutamine, glutamic acid and aspartic acid, which can serve as sole nitrogen sources for the unnodulated plant did not influence nitrogenase activity of effective nodules, even at high concetrations. Ammonia and nitrate suppressed symbiotic nitrogen fixation in vivo only at concentrations much higher than those needed for suppression of nitrogenase activity in free living nitrogen fixing bacteria. The kinetics of suppression were slow compared with that of free living nitrogen fixing bacteria. On the other hand, nitrite, which acts as a direct inhibitor of nitrogenase, suppressed very quickly and at low concentrations. Glutamic acid and glutamine enhanced the effect of ammonia dramatically, while the suppression by nitrate was enhanced only slightly.

  13. Functional characterization of aroA from Rhizobium leguminosarum with significant glyphosate tolerance in transgenic Arabidopsis.

    Science.gov (United States)

    Han, Jing; Tian, Yong-Sheng; Xu, Jing; Wang, Li-Juan; Wang, Bo; Peng, Ri-He; Yao, Quan-Hong

    2014-09-01

    Glyphosate is the active component of the top-selling herbicide, the phytotoxicity of which is due to its inhibition of the shikimic acid pathway. 5-Enolpyruvylshikimate-3-phosphate synthase (EPSPS) is a key enzyme in the shikimic acid pathway. Glyphosate tolerance in plants can be achieved by the expression of a glyphosate-insensitive aroA gene (EPSPS). In this study, we used a PCR-based two-step DNA synthesis method to synthesize a new aroA gene (aroAR. leguminosarum) from Rhizobium leguminosarum. In vitro glyphosate sensitivity assays showed that aroAR. leguminosarum is glyphosate tolerant. The new gene was then expressed in E. coli and key kinetic values of the purified enzyme were determined. Furthermore, we transformed the aroA gene into Arabidopsis thaliana by the floral dip method. Transgenic Arabidopsis with the aroAR. leguminosarum gene was obtained to prove its potential use in developing glyphosate-resistant crops.

  14. Inhibition of nodule development by multicopy promoters of Rhizobium meliloti nif/fix genes

    Institute of Scientific and Technical Information of China (English)

    吴桐; 朱家璧; 俞冠翘; 沈善炯

    1995-01-01

    Using luc gene as a reporter to study the activation of Rhizobium meliloti nif/fix genes in thedevelopment of symbiosis,the authors observed that nodule development and nitrogen fixation were inhibitedby both multicopy promoters of nifHDK and fixABCX.The phenotype of R.meliloti containing multicopynif/fix promoters appeared exactly like that of nifA mutant.Using lacZ as a reporter,the authors got the same re-sults.By contrast,the rhizobia containing low-copy promoters of nif/fix genes were normal fornodule development and nitrogen fixation.These results substantiate the evidence that the product of nifAgene not only acts as a transcriptional activator of nif/fix genes,but also plays an important role in thedevelopment of root nodules.

  15. Novel high- and low-copy stable cosmids for use in Agrobacterium and Rhizobium.

    Science.gov (United States)

    Gallie, D R; Novak, S; Kado, C I

    1985-09-01

    Presented are a set of cosmids based on the unit copy Agrobacterium plasmid, pTAR, and the high-copy-number mutant plasmid, pUCD500, of pTiC58. The addition of a par function derived from pTAR to the vectors allowed them to be stably maintained throughout the cell population in the absence of selective pressure. These vectors, designed for Agrobacterium and Rhizobium, also work in Escherichia coli. The vectors can be cotransferred to Rhizobiaceae from E. coli with the helper plasmid, pRK2013. The pTiC58 origin containing vectors, pUCD1000 and pUCD1001 were found to be incompatible with a 250-kb plasmid harbored by R. meliloti RM102Z1. RM102Z1(pUCD1000) was still capable of nodulating roots in alfalfa.

  16. Mekanisme Penambatan Nitrogen Udara oleh Bakteri Rhizobium Menginspirasi Perkembangan Teknologi Pemupukan Organik yang Ramah Lingkungan

    Directory of Open Access Journals (Sweden)

    GEDE MENAKA ADNYANA

    2014-01-01

    Full Text Available Interaction of microbes with human living in the nature are able to seen from their capabilitiesimproving the environmental by composting waste of agriculture to become organic fertilizer. In thecontrary, the epidemic and infectious phatogens are also its contribution. In agriculture sector, the livingof microbes has been explored to keep the soil fertile, and to improve growth and plant production.The symbiosis of Rhizobium bacteria with the specific host plant from legumes is able to run because ofboth side giving a signal, where host plant give an organic molecoles called inducer. From the bacteriaside, also give an organic materials called nod factor. The step of nitrogen fixation mechanism can bedescribed from infection of root legume as the first step, followed by the nitrogen fixation by thebacteroid and synthesis of the nitrogen organic by host plant as the last step. These natural processesinspire finding and development of the ecologically organic fertilizer technology.

  17. Genome sequence of the Trifolium rueppellianum -nodulating Rhizobium leguminosarum bv. trifolii strain WSM2012.

    Science.gov (United States)

    Reeve, Wayne; Melino, Vanessa; Ardley, Julie; Tian, Rui; De Meyer, Sofie; Terpolilli, Jason; Tiwari, Ravi; Yates, Ronald; O'Hara, Graham; Howieson, John; Ninawi, Mohamed; Held, Brittany; Bruce, David; Detter, Chris; Tapia, Roxanne; Han, Cliff; Wei, Chia-Lin; Huntemann, Marcel; Han, James; Chen, I-Min; Mavromatis, Konstantinos; Markowitz, Victor; Szeto, Ernest; Ivanova, Natalia; Mikhailova, Natalia; Pagani, Ioanna; Pati, Amrita; Goodwin, Lynne; Woyke, Tanja; Kyrpides, Nikos

    2013-12-20

    Rhizobium leguminosarum bv. trifolii WSM2012 (syn. MAR1468) is an aerobic, motile, Gram-negative, non-spore-forming rod that was isolated from an ineffective root nodule recovered from the roots of the annual clover Trifolium rueppellianum Fresen growing in Ethiopia. WSM2012 has a narrow, specialized host range for N2-fixation. Here we describe the features of R. leguminosarum bv. trifolii strain WSM2012, together with genome sequence information and annotation. The 7,180,565 bp high-quality-draft genome is arranged into 6 scaffolds of 68 contigs, contains 7,080 protein-coding genes and 86 RNA-only encoding genes, and is one of 20 rhizobial genomes sequenced as part of the DOE Joint Genome Institute 2010 Community Sequencing Program.

  18. Genome sequence of the South American clover-nodulating Rhizobium leguminosarum bv. trifolii strain WSM597.

    Science.gov (United States)

    Reeve, Wayne; Terpolilli, Jason; Melino, Vanessa; Ardley, Julie; Tian, Rui; De Meyer, Sofie; Tiwari, Ravi; Yates, Ronald; O'Hara, Graham; Howieson, John; Ninawi, Mohamed; Held, Brittany; Bruce, David; Detter, Chris; Tapia, Roxanne; Han, Cliff; Wei, Chia-Lin; Huntemann, Marcel; Han, James; Chen, I-Min; Mavromatis, Konstantinos; Markowitz, Victor; Ivanova, Natalia; Ovchinnikova, Galina; Pagani, Ioanna; Pati, Amrita; Goodwin, Lynne; Woyke, Tanja; Kyrpides, Nikos

    2013-12-20

    Rhizobium leguminosarum bv. trifolii strain WSM597 is an aerobic, motile, Gram-negative, non-spore-forming rod isolated from a root nodule of the annual clover Trifolium pallidum L. growing at Glencoe Research Station near Tacuarembó, Uruguay. This strain is generally ineffective for nitrogen (N2) fixation with clovers of Mediterranean, North American and African origin, but is effective on the South American perennial clover T. polymorphum Poir. Here we describe the features of R. leguminosarum bv. trifolii strain WSM597, together with genome sequence information and annotation. The 7,634,384 bp high-quality-draft genome is arranged in 2 scaffolds of 53 contigs, contains 7,394 protein-coding genes and 87 RNA-only encoding genes, and is one of 20 rhizobial genomes sequenced as part of the DOE Joint Genome Institute 2010 Community Sequencing Program.

  19. Genome sequence of the clover-nodulating Rhizobium leguminosarum bv. trifolii strain TA1.

    Science.gov (United States)

    Reeve, Wayne; Tian, Rui; De Meyer, Sofie; Melino, Vanessa; Terpolilli, Jason; Ardley, Julie; Tiwari, Ravi; Howieson, John; Yates, Ronald; O'Hara, Graham; Ninawi, Mohamed; Teshima, Hazuki; Bruce, David; Detter, Chris; Tapia, Roxanne; Han, Cliff; Wei, Chia-Lin; Huntemann, Marcel; Han, James; Chen, I-Min; Mavromatis, Konstantinos; Markowitz, Victor; Ivanova, Natalia; Ovchinnikova, Galina; Pagani, Ioanna; Pati, Amrita; Goodwin, Lynne; Pitluck, Sam; Woyke, Tanja; Kyrpides, Nikos

    2013-12-20

    Rhizobium leguminosarum bv. trifolii strain TA1 is an aerobic, motile, Gram-negative, non-spore-forming rod that is an effective nitrogen fixing microsymbiont on the perennial clovers originating from Europe and the Mediterranean basin. TA1 however is ineffective with many annual and perennial clovers originating from Africa and America. Here we describe the features of R. leguminosarum bv. trifolii strain TA1, together with genome sequence information and annotation. The 8,618,824 bp high-quality-draft genome is arranged in a 6 scaffold of 32 contigs, contains 8,493 protein-coding genes and 83 RNA-only encoding genes, and is one of 20 rhizobial genomes sequenced as part of the DOE Joint Genome Institute 2010 Community Sequencing Program.

  20. Tsukamurella tyrosinosolvens and Rhizobium radiobacter sepsis presenting with septic pulmonary emboli.

    Science.gov (United States)

    Romano, L; Spanu, T; Calista, F; Zappacosta, B; Mignogna, S; Sali, M; Fiori, B; Fadda, G

    2011-07-01

    Septic pulmonary embolism (SPE) is an uncommon, but life-threatening event that is usually associated with extrapulmonary infections. We report the first case of bilateral SPE secondary to a central venous catheter-related bloodstream infection involving pathogens commonly considered environmental contaminants: Tsukamurella tyrosinosolvens and Rhizobium radiobacter. Empirical levofloxacin treatment was confirmed by in vitro susceptibility data and produced prompt clinical improvement, but removal of the infected line proved indispensable for eradication of the infection. Laboratory personnel should be aware of the pathogenic potential of these environmental organisms, particularly in immunocompromised hosts with indwelling catheters. © 2011 The Authors. Clinical Microbiology and Infection © 2011 European Society of Clinical Microbiology and Infectious Diseases.

  1. Potential of the Galega – Rhizobium galegae System for Bioremediation of Oil-Contaminated Soil

    Directory of Open Access Journals (Sweden)

    Minna M. Jussila

    2003-01-01

    Full Text Available Bioremediation potential of the nitrogen-fixing leguminous plant Galega orientalis Lam. and its microsymbiont Rhizobium galegae was evaluated in microcosm and mesocosm scale in oil and BTEX (benzene, toluene, ethylbenzene, xylene contaminated soils, with m-toluate serving as a model for the latter group. G. orientalis and Rhizobium galegae remained viable in m-toluate fractions up to 3000 ppm. Plant growth and nodulation were inhibited in 500 ppm m-toluate, but were restored when plants were transferred to clean medium. In soil, G. orientalis nodulated and showed good growth in 2000 ppm m-toluate as well as in diesel-contaminated soil in the field, where the plant was stimulating bacterial growth in the rhizosphere. A collection of 52 indigenous m-toluate-tolerating bacteria isolated from oil-contaminated rhizosphere of G. orientalis was characterised and identified by classical and molecular biological methods. 16SrDNA PCR-RFLP and (GTG5-PCR genomic fingerprinting combined with partial sequencing indicated the presence of five major lineages of the Bacteria domain. A TOL plasmid-specific xylE-PCR was developed in order to detect both active and potential degraders of m-toluate. The ability to degrade m-toluate in the presence of the gene xylE was detected only within the genus Pseudomonas. The isolates were tested for capacity to grow on m-toluate as their sole carbon and energy source. In laboratory experiments, the best rhizosphere isolates performed equally well to the positive control strain and are good candidates for inoculant production in the future. They have been tagged with marker genes for further studies on colonisation and persistence.

  2. Effect of chickpea in association with Rhizobium to crop productivity and soil fertility

    Directory of Open Access Journals (Sweden)

    Botir Khaitov

    2016-04-01

    Full Text Available The growth, development and yield of chickpea (Cicer ariеtinum L. is strongly influenced by abiotic factors such as salinity and drought in the arid conditions. The use of efficient plant growth promoting bacteria in chickpea production is the best solution to overcome those stresses. In the present study, 10 chickpea rhizobial strains were isolated and purified from the nodules of chickpea genotype grown on middle salinated soils with different chickpea cultivation histories, 3 of them were more efficient in salt tolerance and showed higher nodulation abilities. Local chickpea genotype Uzbekistan-32 was inoculated with selected Rhizobium bacterial strains before planting them to the field condition. Inoculation of plants with strains Rhizobium sp. R4, R6 and R9 significantly increased shoot, root dry matter, and nodule number by 17, 12, and 20% above the uninoculated plants, respectively. The shoot length increased by 52%, root length by 43%, shoot dry weight by 36%, and root dry weight by 64%. Inoculation significantly increased the pod number by 28% and yield up to 55% as compared to control plant. The effective indigenous rhizobial strains isolated in this study from chickpeas on middle salinated soils of Uzbekistan have the characters of broad host range, high nodulation efficiency, efficient N fixation, great salt tolerance. Soil nitrogen, phosphorus and carbon content of the soil at the end of experiments were positive in all the treatments compare control. In this study, we are focused with consideration of the relationship between chickpea and its symbiotic nitrogen-fixing root nodule bacterial strains and how it functions to influence plant productivity and soil fertility.

  3. FORAGE PRODUCTIVITY OF ARBILA (Phaseolus lunatus AT VARIOUS LEVELS OF RHIZOBIUM INOCULANTS AND HARVESTING TIMES

    Directory of Open Access Journals (Sweden)

    B.B. Koten

    2014-10-01

    Full Text Available The study was conducted to evaluate forage productivity of arbila (Phaseolus lunatus as theruminant feed at various levels of rhizobium inoculants and harvesting times, was designed followingcompletely randomized design of factorial pattern with two factors. The first factor was the level ofinoculums (I i.e. I1 (without inoculum, I2 (5 g/kg seed, I3 (10 g/kg seed, and I4 (15 g/kg seed. Thesecond factor was harvesting time (U i.e. U1 (60 days, U2 (80 days, U3 (100 days with 4replications. The variables were N uptake, production of dry matter (DM and organic matter (OM, andpercentage of OM, crude protein (CP, crude fiber (CF, nitrogen free extract (NFE, extract ether (EEand ash of arbila forage (based on DM. The results showed that inoculant treatment at the rate of 15g/kg seed produced the highest percentage of effective nodules (98.72%, and in combination withharvesting age at 100 days each polybag of plant was able to absorb the higest amount of N (688. 10 gwith production of DM 273.81 g, OM production 263.96 g and nutrients content based on DM of about91.14% OM, 33.52% CF, 34.76%, 5.75% EE, 09.37% ash, and 16.16% CP. From the study, it can beconcluded that arbila plants inoculated specific rhizobium Phaseolus vulgaris at the rate of 15 g/kg seedand harvested at 100 days yielded the best forage as feed.

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

    Directory of Open Access Journals (Sweden)

    Tadeusz Zając

    2013-07-01

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

  5. 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.).

    Science.gov (United States)

    Ormeño-Orrillo, Ernesto; Menna, Pâmela; Almeida, Luiz Gonzaga P; Ollero, Francisco Javier; Nicolás, Marisa Fabiana; Pains Rodrigues, Elisete; Shigueyoshi Nakatani, Andre; Silva Batista, Jesiane Stefânia; Oliveira Chueire, Ligia Maria; Souza, Rangel Celso; Ribeiro Vasconcelos, Ana Tereza; Megías, Manuel; Hungria, Mariangela; Martínez-Romero, Esperanza

    2012-12-27

    Rhizobium tropici CIAT 899 and Rhizobium sp. PRF 81 are α-Proteobacteria that establish nitrogen-fixing symbioses with a range of legume hosts. These strains are broadly used in commercial inoculants for application to common bean (Phaseolus vulgaris) in South America and Africa. Both strains display intrinsic resistance to several abiotic stressful conditions such as low soil pH and high temperatures, which are common in tropical environments, and to several antimicrobials, including pesticides. The genetic determinants of these interesting characteristics remain largely unknown. 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. 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.

  6. Studies on the Fermentation Kinetics of Exopolysaccharide by Rhizobium sp. N613%Rhizobium sp.N613合成胞外多糖的发酵动力学研究

    Institute of Scientific and Technical Information of China (English)

    韩勇; 黄晓波; 赵良启

    2006-01-01

    Rhizobium sp.N613合成胞外多糖(REPS)的分批发酵过程和发酵动力学进行了研究.应用Logistic方程和Luedeking-Piret方程,得到了描述Rhizobium sp.N613菌体生长、REPS合成和底物消耗的动力学模型.模型反映了该菌株合成REPS分批发酵过程的动力学特征,模型值与实验数据拟合良好.对Rhizobium sp.N613发酵动力学模型和合成REPS的生理学特性进行了分析,优化了合成REPS的发酵工艺,补料分批发酵实验结果表明,REPS产量从8.21 g·L-1提高到 11.31 g·L-1.

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

    Directory of Open Access Journals (Sweden)

    Isnia Aparecida de Oliveira

    2000-03-01

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

  8. Inoculation of the nonlegume Capsicum annuum L. with Rhizobium strains. 2. Changes in sterols, triterpenes, fatty acids, and volatile compounds.

    Science.gov (United States)

    Silva, Luís R; Azevedo, Jessica; Pereira, Maria J; Carro, Lorena; Velazquez, Encarna; Peix, Alvaro; Valentão, Patrícia; Andrade, Paula B

    2014-01-22

    Peppers (Capsicum spp.) are consumed worldwide, imparting flavor, aroma, and color to foods, additionally containing high concentrations of biofunctional compounds. This is the first report about the effect of the inoculation of two Rhizobium strains on sterols, triterpenes, fatty acids, and volatile compounds of leaves and fruits of pepper (Capsicum annuum L.) plants. Generally, inoculation with strain TVP08 led to the major changes, being observed a decrease of sterols and triterpenes and an increase of fatty acids, which are related to higher biomass, growth, and ripening of pepper fruits. The increase of volatile compounds may reflect the elicitation of plant defense after inoculation, since the content on methyl salicylate was significantly increased in inoculated material. The findings suggest that inoculation with Rhizobium strains may be employed to manipulate the content of interesting metabolites in pepper leaves and fruits, increasing potential health benefits and defense abilities of inoculated plants.

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

    DEFF Research Database (Denmark)

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

    1986-01-01

    The effect of genetic factors in Rhizobium on host plant biomass production and on the carbon costs of N2 fixation in pea root nodules was studied. Nine strains of Rhizobium leguminosarum were constructed, each containing one of three symbiotic plasmids in combination with one of three different...... with the background of B151. The relationship between nitrogenase activity, carbon costs of N2 fixation and host plant biomass production is discussed....... the lowest carbon costs of N2 fixation (7.10–8.10 μmol C/μmol 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...

  10. Stimulation of indoleacetic acid production in a Rhizobium isolate of Vigna mungo by root nodule phenolic acids.

    Science.gov (United States)

    Mandal, Santi M; Mandal, Santi; Mandal, Mahitosh; Das, Amit K; Das, Amit; Pati, Bikas R; Pati, Bikas; Ghosh, Ananta K; Ghosh, Ananta

    2009-04-01

    The influence of endogenous root nodules phenolic acids on indoleacetic acid (IAA) production by its symbiont (Rhizobium) was examined. The root nodules contain higher amount of IAA and phenolic acids than non-nodulated roots. Presence of IAA metabolizing enzymes, IAA oxidase, peroxidase, and polyphenol oxidase indicate the metabolism of IAA in the nodules and roots. Three most abundant endogenous root nodule phenolic acids (protocatechuic acid, 4-hydroxybenzaldehyde and p-coumaric acid) have been identified and their effects on IAA production by the symbiont have been studied in L-tryptophan supplemented yeast extract basal medium. Protocatechuic acid (1.5 microg ml(-1)) showed maximum stimulation (2.15-fold over control) of IAA production in rhizobial culture. These results indicate that the phenolic acids present in the nodule might serve as a stimulator for IAA production by the symbiont (Rhizobium).

  11. 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.

  12. 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.

  13. Rhizobium meliloti genes required for C4-dicarboxylate transport and symbiotic nitrogen fixation are located on a megaplasmid.

    OpenAIRE

    Watson, R J; Chan, Y K; Wheatcroft, R; Yang, A. F.; Han, S. H.

    1988-01-01

    A mutant of Rhizobium meliloti unable to transport C4 dicarboxylates (dct) was isolated after Tn5 mutagenesis. The mutant, 4F6, could not grow on aspartate or the tricarboxylic acid cycle intermediates succinate, fumarate, or malate. It produced symbiotically ineffective nodules on Medicago sativa in which bacteroids appeared normal, but the symbiotic zone was reduced and the plant cells contained numerous starch granules at their peripheries. Cosmids containing the dct region were obtained b...

  14. Attenuation of Symbiotic Effectiveness by Rhizobium meliloti SAF22 Related to the Presence of a Cryptic Plasmid

    OpenAIRE

    Velazquez, E.; Mateos, P. F.; Pedrero, P.; Dazzo, F. B.; Martinez-Molina, E.

    1995-01-01

    Several wild-type strains of Rhizobium meliloti isolated from alfalfa nodules exhibited different plasmid profiles, yet did not differ in growth rate in yeast-mannitol medium, utilization of 43 different carbon sources, intrinsic resistance to 14 antibiotics, or detection of 16 enzyme activities. In contrast, three measures of effectiveness in symbiotic nitrogen fixation with alfalfa (shoot length, dry weight, and nitrogen content) indicated that R. meliloti SAF22, whose plasmid profile diffe...

  15. Characterization of Rhizobium naphthalenivorans sp. nov. with special emphasis on aromatic compound degradation and multilocus sequence analysis of housekeeping genes.

    Science.gov (United States)

    Kaiya, Shinichi; Rubaba, Owen; Yoshida, Naoko; Yamada, Takeshi; Hiraishi, Akira

    2012-01-01

    Three strains of aerobic chemoorganotrophic naphthalene-degrading bacteria (designated TSY03b(T), TSY04, and TSW01) isolated from sediment of a polychlorinated-dioxin-transforming microcosm were characterized. These strains had Gram-negative-stained, rod-shaped cells measuring 0.6‒0.9 μm in width and 1.2‒3.0 μm in length and were motile by means of peritrichous flagella. Naphthalene was utilized as the sole carbon and energy source, and the transcription of a putative aromatic-ring hydroxylating gene was inducible by naphthalene. The major component of cellular fatty acids was summed feature 8 (C18:1ω7c and/or C18:1ω6c), and significant proportions of C18:0 and C19:0 cyclo ω8cis were also found. The major respiratory quinone was ubiquinone-10. The G+C content of the DNA was 60.3‒60.9 mol%. Phylogenetic analyses by studying sequence information on the housekeeping atpD, dnaK, glnII, gyrB, and recA genes as well as on 16S rRNA genes and the 16S-23S rDNA internal transcribed spacer region revealed that the strains grouped with members of the genus Rhizobium, with Rhizobium selenitireducens as their closest relative but formed a distinct lineage at the species level. This was confirmed by genomic DNA-DNA hybridization studies. These phenotypic, genotypic, and phylogenetic data strongly suggest that our isolates should be classified under a novel species of the genus Rhizobium. Thus, we propose the name Rhizobium naphthalenivorans sp. nov. to accommodate the novel isolates. The type strain is TSY03b(T) (= NBRC 107585T = KCTC 23252T).

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

    OpenAIRE

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

    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...

  17. Rhizobium sp.N613胞外多糖的抗氧化活性%Antioxidant Activity of Exopolysaccharide from Rhizobium sp.N613

    Institute of Scientific and Technical Information of China (English)

    陈艳丽; 任盛; 魏国琴; 吕利华; 赵良启

    2010-01-01

    以铁氰化钾和铁离子为检测系统测定了Rhizobium sp.N613胞外多糖(REPS)对氧化物的还原力;H2O2和Fe2+为羟自由基生成系统检测了REPS对羟自由基的清除作用;邻苯三酚自氧化法检测了REPS对超氧阴离子的清除作用;并体外检测了PEPS对H2O2引起的氧化溶血现象的抑制作用及对小鼠肝组织脂质过氧化损伤的保护作用.结果显示,REPS对氧化物具有明显的还原力,其对羟自由基的清除作用达到35.46%(多糖浓度为2 mg/mL),对超氧阴离子的清除作用达到36.84%(多糖浓度为0.78mg/mL),对H2O2引起的氧化溶血现象的抑制作用达到43.84%(多糖浓度为1.14 mg/mL),对小鼠肝组织脂质过氧化的保护作用达到34.46%(多糖浓度为1.14 mg/mL),表明REPS具有良好的抗氧化作用,有着重要的应用价值.

  18. 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.

  19. Effcet of Rhizobium Inoculation on Growth and Nodulation of Albizzia procera,Albizzia lebbeck and Leucaena leucocephala

    Institute of Scientific and Technical Information of China (English)

    U.K.ARYAL; M.A.U.MRIDHA; 等

    1999-01-01

    Effects of inoculation of Rhizobium suspension on nodulation and plant growth were examined with Albizzia procera,Albizzia lebbeck and Leucaena leucocephala seedlings grown on sterilized and non-sterilized soil media.Inoculation resulted in nodule number increases of 28.6,29.02and 23.9 times in sterilized soil and 3.4,3.6and 3.27 times in non-sterilized soil for A.procera,A.lebbeck and L.leucocephala seedlings respectively.Total dry mass increased by 127.6%,66.7%and 60.7% in sterilized soil and 100%,95.5%and 52.65% in non-sterilized soil for these three legume trees,respectively,after a period of two months.Significantly high inoculation responses of oot length,root diameter,collar diameter,shoot length,and dry mass of root,shoot,leaves and nodules were also observed in both steilized and non-sterilized soil media as compared to respective control treatments,The response to inoculation was strong in sterilized and modest in non-sterilized soils.The significantly higher response to Rhizobium inoculation over control in all the species tested suggested that application of Rhizobium greatly enhanced plant growth ,nodulation,biomass production and nitrogen-fixing activity of the nodules.

  20. Calcium-dependent regulation of genes for plant nodulation in Rhizobium leguminosarum detected by iTRAQ quantitative proteomic analysis.

    Science.gov (United States)

    Arrigoni, Giorgio; Tolin, Serena; Moscatiello, Roberto; Masi, Antonio; Navazio, Lorella; Squartini, Andrea

    2013-11-01

    Rhizobia, the nitrogen-fixing bacterial symbionts of legumes, represent an agricultural application of primary relevance and a model of plant-microbe molecular dialogues. We recently described rhizobium proteome alterations induced by plant flavonoids using iTRAQ. Herein, we further extend that experimentation, proving that the transient elevation in cytosolic calcium is a key signaling event necessary for the expression of the nodulation (nod) genes. Ca(2+) involvement in nodulation is a novel issue that we recently flagged with genetic and physiological approaches and that hereby we demonstrate also by proteomics. Exploiting the multiple combinations of 4-plex iTRAQ, we analyzed Rhizobium leguminosarum cultures grown with or without the nod gene-inducing plant flavonoid naringenin and in the presence or absence of the extracellular Ca(2+) chelator EGTA. We quantified over a thousand proteins, 189 of which significantly altered upon naringenin and/or EGTA stimulation. The expression of NodA, highly induced by naringenin, is strongly reduced when calcium availability is limited by EGTA. This confirms, from a proteomic perspective, that a Ca(2+) influx is a necessary early step in flavonoid-mediated legume nodulation by rhizobia. We also observed other proteins affected by the different treatments, whose identities and roles in nodulation and rhizobium physiology are likewise discussed.

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    African Journals Online (AJOL)

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  2. 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

    OpenAIRE

    1998-01-01

    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 relati...

  3. 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.

  4. Et kors er ikke bare et kors

    DEFF Research Database (Denmark)

    Bach-Nielsen, Carsten

    2015-01-01

    Om et kors, der er rejst uden for den danske kirke i Bruxelles; formodentlig en afledning af det såkaldte Brabanterkors.......Om et kors, der er rejst uden for den danske kirke i Bruxelles; formodentlig en afledning af det såkaldte Brabanterkors....

  5. Characterization of sequences downstream from transcriptional start site of Rhizobium meliloti nifHDK promoter

    Institute of Scientific and Technical Information of China (English)

    高云峰; 吴桐; 朱家璧; 俞冠翘; 沈善炯

    1997-01-01

    In free-living state, the nifHDK promoter P1 of Rhizobium meliloti is induced in response to mi-croaerobiosis and expressed to a high level, while the fixABCX promoter P2 is not. The sequences upstream from both P1 and P2 share extended homology (about 85% ), which are about 160 bp in length, but the sequences downstream of the respective transcriptional start site are different. When the downstream sequence (DS) of P2 was replaced by the corresponding fragment from+ 17 to + 61 of P1, the expression of P2 is greatly increased under free-living condi-tion by lowering the oxygen tension, and the activity of P2 promoter can also be significantly enhanced in E. coli by the NifA protein. The difference between the DS regions of P1 and P2 promoter resulted in different expressions of P1 and P2 promoter under free-living microaerobic condition and in E. coli. The expression of P2 does not depend on the downstream sequences from the promoter element during symbiosis. Primer extension experiments identified the

  6. 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.

  7. Production of extracellular biopolymers and identification of intracellular proteins and Rhizobium tropici.

    Science.gov (United States)

    Oliveira, José; Figueiredo, Marcia; Silva, Marcia; Malta, Marília; Vendruscolo, Claire; Almeida, Hélio

    2012-12-01

    The objective of this study was to identify species of rhizobia (from the IPA 403 and IPA 49 isolates), to assess the physico-chemical characteristics of the biopolymers produced by these rhizobia and to determine the soluble intracellular proteins that are present in these rhizobia. The polysaccharides containing acetyl and pyruvic acid groups that were produced by different strains that had been cultivated in yeast extract mannitol (YEM) medium for 132, 144, and 168 h were evaluated for yield, viscosity, and concentration. Based on the analysis of their partial 16S rDNA sequences, both isolates were identified as Rhizobium tropici. The polymers produced in liquid YEM medium were recovered, dried and weighed to determine culture yield. Soluble intracellular proteins were identified through the techniques of 2D-PAGE and mass spectrometry for cultures that were cultivated for 168 h. The largest biopolymer yield and the highest viscosity and concentration of acetyl and pyruvic acids were obtained from the IPA 403 isolate after 168 h of culture. The proteins that were identified for the CIAT 899 isolate included elongation factor TU, a chaperone; GroE/GroEs and a putative glycosyltransferase, all of which catalyze the production of polysaccharides. For the IPA 403 strain, dinitrogenase and nitrogenase iron proteins were found. In the IPA 49 strain, glyceraldehyde-3-phosphate dehydrogenase was found along with two other proteins, the beta subunit of an electron-transferring flavoprotein and a dehydrogenase.

  8. Policing the legume-Rhizobium symbiosis: a critical test of partner choice.

    Science.gov (United States)

    Westhoek, Annet; Field, Elsa; Rehling, Finn; Mulley, Geraldine; Webb, Isabel; Poole, Philip S; Turnbull, Lindsay A

    2017-05-03

    In legume-Rhizobium symbioses, specialised soil bacteria fix atmospheric nitrogen in return for carbon. However, ineffective strains can arise, making discrimination essential. Discrimination can occur via partner choice, where legumes prevent ineffective strains from entering, or via sanctioning, where plants provide fewer resources. Several studies have inferred that legumes exercise partner choice, but the rhizobia compared were not otherwise isogenic. To test when and how plants discriminate ineffective strains we developed sets of fixing and non-fixing strains that differed only in the expression of nifH - essential for nitrogen fixation - and could be visualised using marker genes. We show that the plant is unable to select against the non-fixing strain at the point of entry, but that non-fixing nodules are sanctioned. We also used the technique to characterise mixed nodules (containing both a fixing and a non-fixing strain), whose frequency could be predicted using a simple diffusion model. We discuss that sanctioning is likely to evolve in preference to partner choice in any symbiosis where partner quality cannot be adequately assessed until goods or services are actively exchanged.

  9. Regulation of nitrogen metabolism is altered in a glnB mutant strain of Rhizobium leguminosarum.

    Science.gov (United States)

    Amar, M; Patriarca, E J; Manco, G; Bernard, P; Riccio, A; Lamberti, A; Defez, R; Iaccarino, M

    1994-02-01

    We isolated a Rhizobium leguminosarum mutant strain altered in the glnB gene. This event, which has never been described in the Rhizobiaceae, is rare in comparison to mutants isolated in the contiguous gene, glnA. The glnB mutation removes the glnBA promoter but in vivo does not prevent glnA expression from its own promoter, which is not nitrogen regulated. The glnB mutant strain does not grow on nitrate as a sole nitrogen source and it is Nod+, Fix+. Two -24/-12 promoters, for the glnII and glnBA genes, are constitutively expressed in the glnB mutant, while two -35/-10-like promoters for glnA and ntrBC are unaffected. We propose that the glnB gene product, the PII protein, plays a negative role in the ability of NtrC to activate transcription from its target promoters and a positive role in the mechanism of nitrate utilization.

  10. Nodules Initiated by Rhizobium meliloti Exopolysaccharide Mutants Lack a Discrete, Persistent Nodule Meristem 1

    Science.gov (United States)

    Yang, Cheng; Signer, Ethan R.; Hirsch, Ann M.

    1992-01-01

    Infection of alfalfa with Rhizobium meliloti exo mutants deficient in exopolysaccharide results in abnormal root nodules that are devoid of bacteria and fail to fix nitrogen. Here we report further characterization of these abnormal nodules. Tightly curled root hairs or shepherd's crooks were found after inoculation with Rm 1021-derived exo mutants, but curling was delayed compared with wild-type Rm 1021. Infection threads were initiated in curled root hairs by mutants as well as by wild-type R. meliloti, but the exo mutant-induced threads aborted within the peripheral cells of the developing nodule. Also, nodules elicited by Rm 1021-derived exo mutants were more likely to develop on secondary roots than on the primary root. In contrast with wild-type R. meliloti-induced nodules, the exo mutant-induced nodules lacked a well defined apical meristem, presumably due to the abortion of the infection threads. The relationship of these findings to the physiology of nodule development is discussed. ImagesFigure 3Figure 1Figure 2Figure 4 PMID:16668605

  11. Effect of leguminous lectins on the growth of Rhizobium tropici CIAT899.

    Science.gov (United States)

    de Vasconcelos, Mayron Alves; Cunha, Cláudio Oliveira; Arruda, Francisco Vassiliepe Sousa; Carneiro, Victor Alves; Bastos, Rafaela Mesquita; Mercante, Fábio Martins; do Nascimento, Kyria Santiago; Cavada, Benildo Sousa; dos Santos, Ricardo Pires; Teixeira, Edson Holanda

    2013-05-17

    Rhizobium tropici is a Gram-negative bacterium that induces nodules and fixed atmospheric nitrogen in symbiotic association with Phaseolus vulgaris (common bean) and some other leguminous species. Lectins are proteins that specifically bind to carbohydrates and, consequently, modulate different biological functions. In this study, the d-glucose/ d-mannose-binding lectins (from seeds of Dioclea megacarpa, D. rostrata and D. violacea) and D-galactose-binding lectins (from seeds of Bauhinia variegata, Erythina velutina and Vatairea macrocarpa) were purified using chromatographic techniques and evaluated for their effect on the growth of R. tropici CIAT899. All lectins were assayed with a satisfactory degree of purity according to SDS-PAGE analysis, and stimulated bacterial growth; in particular, the Dioclea rostrata lectin was the most active among all tested proteins. As confirmed in the present study, both d-galactose- and d-glucose/d-mannose-binding lectins purified from the seeds of leguminous plants may be powerful biotechnological tools to stimulate the growth of R. tropici CIAT99, thus improving symbiotic interaction between rhizobia and common bean and, hence, the production of this field crop.

  12. Effect of Leguminous Lectins on the Growth of Rhizobium tropici CIAT899

    Directory of Open Access Journals (Sweden)

    Mayron Alves de Vasconcelos

    2013-05-01

    Full Text Available Rhizobium tropici is a Gram-negative bacterium that induces nodules and fixed atmospheric nitrogen in symbiotic association with Phaseolus vulgaris (common bean and some other leguminous species. Lectins are proteins that specifically bind to carbohydrates and, consequently, modulate different biological functions. In this study, the d-glucose/ d-mannose-binding lectins (from seeds of Dioclea megacarpa, D. rostrata and D. violacea and D-galactose-binding lectins (from seeds of Bauhinia variegata, Erythina velutina and Vatairea macrocarpa were purified using chromatographic techniques and evaluated for their effect on the growth of R. tropici CIAT899. All lectins were assayed with a satisfactory degree of purity according to SDS-PAGE analysis, and stimulated bacterial growth; in particular, the Dioclea rostrata lectin was the most active among all tested proteins. As confirmed in the present study, both d-galactose- and d-glucose/d-mannose-binding lectins purified from the seeds of leguminous plants may be powerful biotechnological tools to stimulate the growth of R. tropici CIAT99, thus improving symbiotic interaction between rhizobia and common bean and, hence, the production of this field crop.

  13. Isolation of genes (nif/hup cosmids) involved in hydrogenase and nitrogenase activities in Rhizobium japonicum.

    Science.gov (United States)

    Hom, S S; Graham, L A; Maier, R J

    1985-03-01

    Recombinant cosmids containing a Rhizobium japonicum gene involved in both hydrogenase (Hup) and nitrogenase (Nif) activities were isolated. An R. japonicum gene bank utilizing broad-host-range cosmid pLAFR1 was conjugated into Hup- Nif- R. japonicum strain SR139. Transconjugants containing the nif/hup cosmid were identified by their resistance to tetracycline (Tcr) and ability to grow chemoautotrophically (Aut+) with hydrogen. All Tcr Aut+ transconjugants possessed high levels of H2 uptake activity, as determined amperometrically. Moreover, all Hup+ transconjugants tested possessed the ability to reduce acetylene (Nif+) in soybean nodules. Cosmid DNAs from 19 Hup+ transconjugants were transferred to Escherichia coli by transformation. When the cosmids were restricted with EcoRI, 15 of the 19 cosmids had a restriction pattern with 13.2-, 4.0-, 3.0-, and 2.5-kilobase DNA fragments. Six E. coli transformants containing the nif/hup cosmids were conjugated with strain SR139. All strain SR139 transconjugants were Hup+ Nif+. Moreover, one nif/hup cosmid was transferred to 15 other R. japonicum Hup- mutants. Hup+ transconjugants of six of the Hup- mutants appeared at a frequency of 1.0, whereas the transconjugants of the other nine mutants remained Hup-. These results indicate that the nif/hup gene cosmids contain a gene involved in both nitrogenase and hydrogenase activities and at least one and perhaps other hup genes which are exclusively involved in H2 uptake activity.

  14. Transcriptional profiling of ESTs responsive to Rhizobium vitis from 'Tamnara' grapevines (Vitis sp.).

    Science.gov (United States)

    Choi, Youn Jung; Yun, Hae Keun; Park, Kyo Sun; Noh, Jeong Ho; Heo, Youn Young; Kim, Seung Hui; Kim, Dae Won; Lee, Hee Jae

    2010-09-01

    Genes related with defense responses were screened from the cDNA library constructed with Rhizobium vitis-inoculated or salicylic acid (SA)-treated 'Tamnara' grapevine (Vitis sp.) leaves. Among 13,728 expressed sequence tags (ESTs) from 'Tamnara' grapevine upon R. vitis inoculation and SA treatment, 6776 unigenes containing 1915 contigs and 4860 singletons were obtained. In gene ontology analysis, there were about 3200 clones related with biological process, 3555 with molecular function, and 3354 with cellular component genes. Proteins of secretory organ (35%), plasma membrane (30%), endoplasmic reticulum (20%), and vacuole (11%) were predicted. Photosynthesis-related genes and defense-related genes were most abundant. Among ESTs, 199 resistance-related ones were mapped to the genome of Vitis vinifera L. with three markers, GLP1-12, MHD98, and MHD145, which are known to be linked to resistance against powdery mildew. Approximately, 120 simple sequence repeats (SSRs) detected in cDNAs could be used as EST-derived SSR markers in disease resistant grape breeding. Copyright 2010 Elsevier GmbH. All rights reserved.

  15. 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)

  16. Molecular phylogenetic analysis of Rhizobium sullae isolated from Algerian Hedysarum flexuosum.

    Science.gov (United States)

    Aliliche, Khadidja; Beghalem, Hamida; Landoulsi, Ahmed; Chriki, Ali

    2016-07-01

    Isolates from root nodules of Hedysarum flexuosum, sampled from north region of Algeria, were analyzed on the basis of their phenotypic and molecular characteristics. They were tested for their tolerance to NaCl, pH, temperatures, antibiotics and heavy metals resistance. Interestingly, the isolate Hf_04N appeared resistant to ZnCl2 (50 μg/mL) and grew at high saline concentration up to 9 %. The phylogenetic positions of five isolates were studied by comparative sequence analysis of 16S rRNA, recA, nifH and nodD genes. There were grouped close to the Rhizobium sullae type strain in relation to their 16S rRNA, recA and nifH genes-based phylogenies. By contrast, the tree of nodD gene was not congruent with ribosomal, housekeeping and nitrogen fixation genes. We suggest that our strains have a novel nodD gene. The detection of conserved domains of NodD protein and nitrogenase reductase enzyme, confirm their ability to nodulate and fix nitrogen.

  17. 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.

  18. The RPG gene of Medicago truncatula controls Rhizobium-directed polar growth during infection.

    Science.gov (United States)

    Arrighi, Jean-François; Godfroy, Olivier; de Billy, Françoise; Saurat, Olivier; Jauneau, Alain; Gough, Clare

    2008-07-15

    Rhizobia can infect roots of host legume plants and induce new organs called nodules, in which they fix atmospheric nitrogen. Infection generally starts with root hair curling, then proceeds inside newly formed, intracellular tubular structures called infection threads. A successful symbiotic interaction relies on infection threads advancing rapidly at their tips by polar growth through successive cell layers of the root toward developing nodule primordia. To identify a plant component that controls this tip growth process, we characterized a symbiotic mutant of Medicago truncatula, called rpg for rhizobium-directed polar growth. In this mutant, nitrogen-fixing nodules were rarely formed due to abnormally thick and slowly progressing infection threads. Root hair curling was also abnormal, indicating that the RPG gene fulfils an essential function in the process whereby rhizobia manage to dominate the process of induced tip growth for root hair infection. Map-based cloning of RPG revealed a member of a previously unknown plant-specific gene family encoding putative long coiled-coil proteins we have called RRPs (RPG-related proteins) and characterized by an "RRP domain" specific to this family. RPG expression was strongly associated with rhizobial infection, and the RPG protein showed a nuclear localization, indicating that this symbiotic gene constitutes an important component of symbiotic signaling.

  19. Alfalfa Enod12 genes are differentially regulated during nodule development by Nod factors and Rhizobium invasion.

    Science.gov (United States)

    Bauer, P; Crespi, M D; Szécsi, J; Allison, L A; Schultze, M; Ratet, P; Kondorosi, E; Kondorosi, A

    1994-01-01

    MsEnod12A and MsEnod12B are two early nodulin genes from alfalfa (Medicago sativa). Differential expression of these genes was demonstrated using a reverse transcription-polymerase chain reaction approach. MsEnod12A RNA was detected only in nodules and not in other plant tissues. In contrast, MsEnod12B transcripts were found in nodules and also at low levels in roots, flowers, stems, and leaves. MsEnod12B expression was enhanced in the root early after inoculation with the microsymbiont Rhizobium meliloti and after treatment with purified Nod factors, whereas MsEnod12A induction was detected only when developing nodules were visible. In situ hybridization showed that in nodules, MsEnod12 expression occurred in the infection zone. In empty Fix- nodules the MsEnod12A transcript level was much reduced, and in spontaneous nodules it was not detectable. These data indicate that MsEnod12B expression in roots is related to the action of Nod factors, whereas MsEnod12A expression is associated with the invasion process in nodules. Therefore, alfalfa possesses different mechanisms regulating MsEnod12A and MsEnod12B expression. PMID:8066132

  20. Azide resistance in Rhizobium ciceri linked with superior symbiotic nitrogen fixation.

    Science.gov (United States)

    Bhaskar, V Vijay

    2004-12-01

    Isolated azide resistant (AzR) native R. ciceri strain 18-7 was resistant to sodium azide at 10 microg/ml. To find if nif-reiteration is responsible for azide resistance and linked to superior symbiotic nitrogen fixation, transposon (Tn5) induced azide sensitive mutants were generated. Using 4 kb nif-reiterated Sinorhizobium meliloti DNA, a clone C4 that complemented azide sensitivity was isolated by DNA hybridization from genomic library of chickpea Rhizobium strain Rcd301. EcoRI restriction mapping revealed the presence of 7 recognition sites with a total insert size of 19.17 kb. Restriction analysis of C4 clone and nif-reiterated DNA (pRK 290.7) with EcoRI and XhoI revealed similar banding pattern. Wild type strain 18-7, mutant M126 and complemented mutant M126(C4) were characterized for symbiotic properties (viz., acetylene reduction assay, total nitrogen content, nodule number and fresh and dry weight of the infected plants) and explanta nitrogenase activity. Our results suggested that azide resistance, nif-reiteration, and superior symbiotic effectiveness were interlinked with no correlation between ex-planta nitrogenase activity and azide resistance in R. ciceri.

  1. Transfer of an indigenous plasmid of Rhizobium loti to other rhizobia and Agrobacterium tumefaciens.

    Science.gov (United States)

    Pankhurst, C E; Broughton, W J; Wieneke, U

    1983-08-01

    Rhizobium loti strains NZP2037 and NZP2213 were each found to contain a single large plasmid: pRlo2037a (240 MDal) and pRlo2213a (120 MDal), respectively. Plasmid DNA present in crude cell lysates of each strain and purified pRlo2037a DNA did not hybridize with pID1, a recombinant plasmid containing part of the nitrogen fixation (nif) region of R. meliloti, indicating that nif genes were not present on these plasmids. The transposon Tn5 was inserted into pRlo2037a and this plasmid was then transferred into R. leguminosarum, R. meliloti and Agrobacterium tumefaciens. All transconjugants failed to nodulate Lotus pedunculatus, suggesting that the ability to nodulate this legume was also not carried on pRlo2037a. Transfer of pRlo2037a to R. loti strain NZP2213 did not alter the Nod+ Fix- phenotype of this strain for L. pedunculatus. Determinants for flavolan resistance, believed to be necessary for effective nodulation of L. pedunculatus, were not carried on pRlo2037a. These data suggest that nodulation, nitrogen fixation and flavolan resistance genes are not present on the large plasmid in R. loti strain NZP2037.

  2. Characterization of the urease gene cluster from Rhizobium leguminosarum bv. viciae.

    Science.gov (United States)

    Toffanin, Annita; Cadahia, Esther; Imperial, Juan; Ruiz-Argüeso, Tomás; Palacios, Manuel

    2002-04-01

    Moderate levels of urease activity (ca. 300 mU mg(-1)) were detected in Rhizobium leguminosarum bv. viciae UPM791 vegetative cells. This activity did not require urea for induction and was partially repressed by the addition of ammonium into the medium. Lower levels of urease activity (ca. 100 mU mg(-1)) were detected also in pea bacteroids. A DNA region of ca. 9 kb containing the urease structural genes ( ureA, ureB and ureC), accessory genes ( ureD, ureE, ureF, and ureG), and five additional ORFs ( orf83, orf135, orf207, orf223, and orf287) encoding proteins of unknown function was sequenced. Three of these ORFs ( orf83, orf135 and orf207) have a homologous counterpart in a gene cluster from Sinorhizobium meliloti, reported to be involved in urease and hydrogenase activities. R. leguminosarum mutant strains carrying Tn 5 insertions within this region exhibited a urease-negative phenotype, but induced wild-type levels of hydrogenase and nitrogenase activities in bacteroids. orf287 encodes a potential transmembrane protein with a C-terminal GGDEF domain. A mutant affected in orf287 exhibited normal levels of urease activity in culture cells. Experiments aimed at cross-complementing Ni-binding proteins required for urease and hydrogenase synthesis (UreE and HypB, respectively) indicated that these two proteins are not functionally interchangeable in R. leguminosarum.

  3. Isolation of Rhizobium Spp. Bacteria which as Used Microbial Fertilizer from Wild Leguminosarum Plants

    Directory of Open Access Journals (Sweden)

    Hatice Öğütcü

    2014-04-01

    Full Text Available In our study used wild leguminous plants (Medicago sativa, M. lupulina and M. varia Erzurum belongs to the high altitude (2000 - 2500m regions ( Palandöken mountain, Alibaba mountain, Turnagöl mountain, Hasanbaba mountain, Eğerli mountain, Yıldırım mountain, Çubuklu mountain, Deveboynu locality, Kayakyolu locality, Telsizler and Dumlu hill were collected during the months of June and July. Nodules were obtained from this plant were sterilized, YMA (Yeast Mannitol Agar plates were streaked and petri dishes 28+1ºC were incubated for 3-5 days. Colonies appear after incubation typically constitute (white, clear or slightly opaque, mucosity, round, raised 39 isolates were selected and transferred to tubes and refrigerated YMA were stored at +4ºC. In the next stage, cytological and biochemical analyzes of these isolates were studied to determine. For this purpose isolates; YMA containing bromothymol blue and congo red reproduction, gram stain reaction, movement and subjected to catalase and oxidase tests were evaluated. The cytological and biochemical analysis of results showed that 28 of 39 strains belonged to Rhizobium spp.

  4. Effect of different substrates on growth of Mimosa bimucronata seedlings inoculate with rhizobium

    Directory of Open Access Journals (Sweden)

    Juliana Müller Freire

    2017-06-01

    Full Text Available The objective of this study was to evaluate the growth response of Mimosa bimucronata (DC O. Kuntze seedlings in nursery conditions to inoculation with rhizobium strains previously selected using different substrates. An experimental design of randomized blocks with split plots was used, testing three substrates (pure organic-containing clay, sand and manure in 1: 1: 1 v: v: v ratio; organomineral mixed with 30% straw and sand with vermiculite in 1: 1 v: v and four N sources (inoculation with strains BR 3461 and BR 3470, control with N fertilization and control without fertilization, totalizing 12 treatments. Height and stem diameter were evaluate after 90 days and shoot, root and nodules dry mass were evaluate after 120 days. Organomineral substrates provided better seedling growth. However, only organic-substrate with straw and sand with vermiculite showed positive responses of plants inoculated with BR3470 strain. The performance of the inoculated seedlings was not higher than that of seedlings fertilized with N. The rate of N applied stimulated nodulation rather than inhibit it.

  5. New Betaproteobacterial Rhizobium Strains Able To Efficiently Nodulate Parapiptadenia rigida (Benth.) Brenan

    Science.gov (United States)

    Taulé, Cecilia; Zabaleta, María; Mareque, Cintia; Platero, Raúl; Sanjurjo, Lucía; Sicardi, Margarita; Frioni, Lillian; Battistoni, Federico

    2012-01-01

    Among the leguminous trees native to Uruguay, Parapiptadenia rigida (Angico), a Mimosoideae legume, is one of the most promising species for agroforestry. Like many other legumes, it is able to establish symbiotic associations with rhizobia and belongs to the group known as nitrogen-fixing trees, which are major components of agroforestry systems. Information about rhizobial symbionts for this genus is scarce, and thus, the aim of this work was to identify and characterize rhizobia associated with P. rigida. A collection of Angico-nodulating isolates was obtained, and 47 isolates were selected for genetic studies. According to enterobacterial repetitive intergenic consensus PCR patterns and restriction fragment length polymorphism analysis of their nifH and 16S rRNA genes, the isolates could be grouped into seven genotypes, including the genera Burkholderia, Cupriavidus, and Rhizobium, among which the Burkholderia genotypes were the predominant group. Phylogenetic studies of nifH, nodA, and nodC sequences from the Burkholderia and the Cupriavidus isolates indicated a close relationship of these genes with those from betaproteobacterial rhizobia (beta-rhizobia) rather than from alphaproteobacterial rhizobia (alpha-rhizobia). In addition, nodulation assays with representative isolates showed that while the Cupriavidus isolates were able to effectively nodulate Mimosa pudica, the Burkholderia isolates produced white and ineffective nodules on this host. PMID:22226956

  6. 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.

  7. Et redskab i formskaben

    DEFF Research Database (Denmark)

    Thomsen, Bente Dahl

    Et innovativt didaktisk projekt, der arbejder med at udvikle et redskab til brug ved undervisningen i formskaben underlagt et universitært system. Det betyder at tidligere praksisbaseret læring i værksteder er omlagt til forskningsbaseret undervisning i auditoriumlignende lokaler. Projektet hvile...

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

  9. 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

    Directory of Open Access Journals (Sweden)

    Patrícia Perondi Anchão Oliveira

    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.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. meliloti 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

  10. Rhizobium cauense sp. nov., isolated from root nodules of the herbaceous legume Kummerowia stipulacea grown in campus lawn soil.

    Science.gov (United States)

    Liu, Tian Yan; Li, Ying; Liu, Xiao Xiao; Sui, Xin Hua; Zhang, Xiao Xia; Wang, En Tao; Chen, Wen Xin; Chen, Wen Feng; Puławska, Joanna

    2012-10-01

    Three bacterial isolates (CCBAU 101002(T), CCBAU 101000 and CCBAU 101001) originating from root nodules of the herbaceous legume Kummerowia stipulacea grown in the campus lawn of China Agricultural University were characterized with a polyphasic taxonomic approach. Comparative 16S rRNA gene sequence analysis showed that the isolates shared 99.85-99.92% sequence similarities and had the highest similarities to the type strains of Rhizobium mesoamericanum (99.31%), R. endophyticum (98.54%), R. tibeticum (98.38%) and R. grahamii (98.23%). Sequence similarity of four concatenated housekeeping genes (atpD, glnII, recA and rpoB) between CCBAU 101002(T) and its closest neighbor (R. grahamii) was 92.05%. DNA-DNA hybridization values between strain CCBAU 101002(T) and the four type strains of the most closely related Rhizobium species were less than 28.4±0.8%. The G+C mol% of the genomic DNA for strain CCBAU 101002(T) was 58.5% (Tm). The major respiratory quinone was ubiquinone (Q-10). Summed feature 8 (18:1ω7cis/18:1ω6cis) and 16:0 were the predominant fatty acids. Strain CCBAU 101002(T) contained phosphatidylcholine and phosphatidylethanolamine as major polar lipids, and phosphatidylglycerol and cardiolipin as minor ones. No glycolipid was detected. Unlike other strains, this novel species could utilize dulcite or sodium pyruvate as sole carbon sources and it was resistant to 2% (w/v) NaCl. On the basis of the polyphasic study, a new species Rhizobium cauense sp. nov. is proposed, with CCBAU 101002(T) (=LMG 26832(T)=HAMBI 3288(T)) as the type strain.

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

    Science.gov (United States)

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

    2015-04-01

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

  12. Isolation of Rhizobium phaseoli Tn5-induced mutants with altered expression of cytochrome terminal oxidases o and aa3.

    Science.gov (United States)

    Soberón, M; Membrillo-Hernández, J; Aguilar, G R; Sánchez, F

    1990-01-01

    Two Rhizobium phaseoli mutants affected in cytochrome expression were obtained by Tn5-mob mutagenesis of the wild-type strain (CE3). Mutant strain CFN031 expressed sevenfold less cytochrome o in culture, expressed cytochrome aa3 under microaerophilic culture conditions, in contrast to strain CE3, and was affected in its vegetative growth properties and proliferation inside plant host cells. Mutant CFN037 expressed cytochrome aa3 under microaerophilic culture conditions, while bacteroid development and nitrogen fixation occurred earlier than in strain CE3. Images FIG. 2 PMID:2155209

  13. ESTABLECIMIENTO Y RESPUESTAS FISIOLÓGICAS DE LA SIMBIOSIS Rhizobium tropici-Leucaena leucocephala EN PRESENCIA DE FENANTRENO Y NAFTALENO

    OpenAIRE

    Carlos LÓPEZ-ORTIZ; Ferrera-Cerrato, Ronald; Alejandro ALARCÓN; Juan José ALMARAZ; Esperanza MARTÍNEZ-ROMERO; Ma. Remedios MENDOZA-LÓPEZ

    2012-01-01

    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 (CloroT) 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/...

  14. 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...

  15. 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...

  16. [Signaling Systems of Rhizobia (Rhizobiaceae) and Leguminous Plants (Fabaceae) upon the Formation of a Legume-Rhizobium Symbiosis (Review)].

    Science.gov (United States)

    Glyan'ko, A K

    2015-01-01

    Data from the literature and our own data on the participation and interrelation of bacterial signaling Nod-factors and components of the calcium, NADPH-oxidase, and NO-synthase signaling systems of a plant at the preinfection and infectious stages of the formation of a legume-rhizobium symbiosis are summarized in this review. The physiological role of Nod-factors, reactive oxygen species (ROS), calcium (Ca2+), NADPH-oxidase, nitric oxide (NO), and their cross influence on the processes determining the formation of symbiotic structures on the roots of the host plant is discussed.

  17. 苜蓿根瘤菌菌剂的研究%Study on Biologicals of Rhizobium Meliloti Dangeard

    Institute of Scientific and Technical Information of China (English)

    常玮; 王炜; 屈新兰

    2004-01-01

    根据新疆气候特点,筛选出一株在耐旱、耐盐碱方面抗性较强的苜蓿根瘤菌Rhizobium sp.XJ67,并对其发酵条件及菌剂保存条件进行研究,结果表明该菌最适生长温度为30℃,最适pH为6.8,发酵液活菌数达19 300×108,菌剂最佳保存条件为冻干剂.

  18. 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...

  19. 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...

  20. Two-dimensional proteome reference map of Rhizobium tropici PRF 81 reveals several symbiotic determinants and strong resemblance with agrobacteria.

    Science.gov (United States)

    Gomes, Douglas Fabiano; Batista, Jesiane Stefania da Silva; Torres, Adalgisa Ribeiro; de Souza Andrade, Diva; Galli-Terasawa, Lygia Vitoria; Hungria, Mariangela

    2012-03-01

    Rhizobium tropici strain PRF 81 is used in commercial inoculants for common-bean crops in Brazil because of its high efficiency in nitrogen fixation and, as in other strains belonging to this species, its tolerance of environmental stresses, representing a useful biological alternative to chemical nitrogen fertilizers. In this study, a proteomic reference map of PRF 81 was obtained by two-dimensional gel electrophoresis and MALDI-TOF/TOF-TOF mass spectrometry. In total, 115 spots representing 109 different proteins were successfully identified, contributing to a better understanding of the rhizobia-legume symbiosis and supporting, at proteomics level, a strong resemblance with agrobacteria.

  1. Improvement of Faba Bean Yield Using Rhizobium/Agrobacterium Inoculant in Low-Fertility Sandy Soil

    Directory of Open Access Journals (Sweden)

    Sameh H. Youseif

    2017-01-01

    Full Text Available Soil fertility is one of the major limiting factors for crop’s productivity in Egypt and the world in general. Biological nitrogen fixation (BNF has a great importance as a non-polluting and a cost-effective way to improve soil fertility through supplying N to different agricultural systems. Faba bean (Vicia faba L. is one of the most efficient nitrogen-fixing legumes that can meet all of their N needs through BNF. Therefore, understanding the impact of rhizobial inoculation and contrasting soil rhizobia on nodulation and N2 fixation in faba bean is crucial to optimize the crop yield, particularly under low fertility soil conditions. This study investigated the symbiotic effectiveness of 17 Rhizobium/Agrobacterium strains previously isolated from different Egyptian governorates in improving the nodulation and N2 fixation in faba bean cv. Giza 843 under controlled greenhouse conditions. Five strains that had a high nitrogen-fixing capacity under greenhouse conditions were subsequently tested in field trials as faba bean inoculants at Ismaillia Governorate in northeast Egypt in comparison with the chemical N-fertilization treatment (96 kg N·ha−1. A starter N-dose (48 kg N·ha−1 was applied in combination with different Rhizobium inoculants. The field experiments were established at sites without a background of inoculation under low fertility sandy soil conditions over two successive winter growing seasons, 2012/2013 and 2013/2014. Under greenhouse conditions, inoculated plants produced significantly higher nodules dry weight, plant biomass, and shoot N-uptake than non-inoculated ones. In the first season (2012/2013, inoculation of field-grown faba bean showed significant improvements in seed yield (3.73–4.36 ton·ha−1 and seed N-yield (138–153 Kg N·ha−1, which were higher than the uninoculated control (48 kg N·ha−1 that produced 2.97 Kg·ha−1 and 95 kg N·ha−1, respectively. Similarly, in the second season (2013

  2. Monstres et murailles, Alexandre et bicornu, mythes et bon sens

    Directory of Open Access Journals (Sweden)

    Jean-Louis Bacqué-Grammont

    2009-05-01

    Full Text Available Parmi les mythes récurrents à travers les lieux et les âges, celui du bâtisseur de murailles défendant une humanité civilisée contre l'Autre, sous ses aspects les plus effrayants, a connu une durable fortune depuis le prototype d'un Alexandre le Grand légendaire jusqu'à des avatars composites, bien vivaces dans nombre de littératures islamiques.En trois points différents de cet inépuisable domaine de recherche, chacun des auteurs a procédé à un sondage sommaire. Il en ressort maint exemple de continuités, de parallélismes et de confluences complexes, mais aussi les premiers signes d'érosion des mythes sous l'effet d'un esprit critique attisé par le vent d'Occident.

  3. Characterization of genes involved in erythritol catabolism in Rhizobium leguminosarum bv. viciae.

    Science.gov (United States)

    Yost, Christopher K; Rath, Amber M; Noel, Tanya C; Hynes, Michael F

    2006-07-01

    A genetic locus encoding erythritol uptake and catabolism genes was identified in Rhizobium leguminosarum bv. viciae, and shown to be plasmid encoded in a wide range of R. leguminosarum strains. A Tn5-B22 mutant (19B-3) unable to grow on erythritol was isolated from a mutant library of R. leguminosarum strain VF39SM. The mutated gene eryF was cloned and partially sequenced, and determined to have a high homology to permease genes of ABC transporters. A cosmid complementing the mutation (pCos42) was identified and was shown to carry all the genes necessary to restore the ability to grow on erythritol to a VF39SM strain cured of pRleVF39f. In the genomic DNA sequence of strain 3841, the gene linked to the mutation in 19B-3 is flanked by a cluster of genes with high homology to the known erythritol catabolic genes from Brucella spp. Through mutagenesis studies, three distinct operons on pCos42 that are required for growth on erythritol were identified: an ABC-transporter operon (eryEFG), a catabolic operon (eryABCD) and an operon (deoR-tpiA2-rpiB) that encodes a gene with significant homology to triosephosphate isomerase (tpiA2). These genes all share high sequence identity to genes in the erythritol catabolism region of Brucella spp., and clustalw alignments suggest that horizontal transfer of the erythritol locus may have occurred between R. leguminosarum and Brucella. Transcription of the eryABCD operon is repressed by EryD and is induced by the presence of erythritol. Mutant 19B-3 was impaired in its ability to compete against wild-type for nodulation of pea plants but was still capable of forming nitrogen-fixing nodules.

  4. Proteomic profiling of Rhizobium tropici PRF 81: identification of conserved and specific responses to heat stress.

    Science.gov (United States)

    Gomes, Douglas Fabiano; Batista, Jesiane Stefânia da Silva; Schiavon, Aline Luiza; Andrade, Diva Souza; Hungria, Mariangela

    2012-05-30

    Rhizobium tropici strain PRF 81 (= SEMIA 4080) has been used in commercial inoculants for application to common-bean crops in Brazil since 1998, due to its high efficiency in fixing nitrogen, competitiveness against indigenous rhizobial populations and capacity to adapt to stressful tropical conditions, representing a key alternative to application of N-fertilizers. The objective of our study was to obtain an overview of adaptive responses to heat stress of strain PRF 81, by analyzing differentially expressed proteins when the bacterium is grown at 28°C and 35°C. Two-dimensional gel electrophoresis (2DE) revealed up-regulation of fifty-nine spots that were identified by MALDI-TOF/TOF-TOF. Differentially expressed proteins were associated with the functional COG categories of metabolism, cellular processes and signaling, information storage and processing. Among the up-regulated proteins, we found some related to conserved heat responses, such as molecular chaperones DnaK and GroEL, and other related proteins, such as translation factors EF-Tu, EF-G, EF-Ts and IF2. Interestingly, several oxidative stress-responsive proteins were also up-regulated, and these results reveal the diversity of adaptation mechanisms presented by this thermotolerant strain, suggesting a cross-talk between heat and oxidative stresses. Our data provide valuable protein-expression information relevant to the ongoing genome sequencing of strain PRF 81, and contributes to our still-poor knowledge of the molecular determinants of the thermotolerance exhibited by R. tropici species.

  5. Reactive Oxygen Species and Nitric Oxide Control Early Steps of the Legume – Rhizobium Symbiotic Interaction

    Science.gov (United States)

    Damiani, Isabelle; Pauly, Nicolas; Puppo, Alain; Brouquisse, Renaud; Boscari, Alexandre

    2016-01-01

    The symbiotic interaction between legumes and nitrogen-fixing rhizobium bacteria leads to the formation of a new organ, the nodule. Early steps of the interaction are characterized by the production of bacterial Nod factors, the reorientation of root-hair tip growth, the formation of an infection thread (IT) in the root hair, and the induction of cell division in inner cortical cells of the root, leading to a nodule primordium formation. Reactive oxygen species (ROS) and nitric oxide (NO) have been detected in early steps of the interaction. ROS/NO are determinant signals to arbitrate the specificity of this mutualistic association and modifications in their content impair the development of the symbiotic association. The decrease of ROS level prevents root hair curling and ITs formation, and that of NO conducts to delayed nodule formation. In root hairs, NADPH oxidases were shown to produce ROS which could be involved in the hair tip growth process. The use of enzyme inhibitors suggests that nitrate reductase and NO synthase-like enzymes are the main route for NO production during the early steps of the interaction. Transcriptomic analyses point to the involvement of ROS and NO in the success of the infection process, the induction of early nodulin gene expression, and the repression of plant defense, thereby favoring the establishment of the symbiosis. The occurrence of an interplay between ROS and NO was further supported by the finding of both S-sulfenylated and S-nitrosylated proteins during early symbiotic interaction, linking ROS/NO production to a redox-based regulation of the symbiotic process. PMID:27092165

  6. 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.

  7. 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

  8. Reactive oxygen species and nitric oxide control early steps of the legume – Rhizobium symbiotic interaction

    Directory of Open Access Journals (Sweden)

    Isabelle eDamiani

    2016-04-01

    Full Text Available The symbiotic interaction between legumes and nitrogen-fixing rhizobium bacteria leads to the formation of a new organ, the nodule. Early steps of the interaction are characterized by the production of bacterial Nod factors, the reorientation of root-hair tip growth, the formation of an infection thread in the root hair, and the induction of cell division in inner cortical cells of the root, leading to a nodule primordium formation. Reactive oxygen species (ROS and nitric oxide (NO have been detected in early steps of the interaction. ROS/NO are determinant signals to arbitrate the specificity of this mutualistic association and modifications in their content impair the development of the symbiotic association. The decrease of ROS level prevents root hair curling and infection threads formation, and that of NO conducts to delayed nodule formation. In root hairs, NADPH oxidases were shown to produce ROS which could be involved in the hair tip growth process. The use of enzyme inhibitors suggests that nitrate reductase and NO synthase-like enzymes are the main route for NO production during the early steps of the interaction. Transcriptomic analyses point to the involvement of ROS and NO in the success of the infection process, the induction of early nodulin gene expression, and the repression of plant defense, thereby favoring the establishment of the symbiosis. The occurrence of an interplay between ROS and NO was further supported by the finding of both S-sulfenylated and S-nitrosylated proteins during early symbiotic interaction, linking ROS/NO production to a redox-based regulation of the symbiotic process.

  9. Trehalose biosynthesis in Rhizobium leguminosarum bv. trifolii and its role in desiccation tolerance.

    Science.gov (United States)

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

    2007-06-01

    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 novo biosynthesis is a common response to desiccation stress in bacteria. In this study we investigated the role of endogenous trehalose synthesis in desiccation tolerance in R. leguminosarum bv. trifolii strain NZP561. Strain NZP561 accumulated trehalose as it entered the stationary phase due to the combined actions of the TreYZ and OtsAB pathways. Mutants deficient in either pathway showed near-wild-type levels of trehalose accumulation, but double otsA treY mutants failed to accumulate any trehalose. The double mutants were more sensitive to the effects of drying, and their survival was impaired compared to that of the wild type when glass beads were coated with the organisms and stored at relative humidities of 5 and 32%. The otsA treY mutants were also less competitive for nodule occupancy. Gene expression studies showed that the otsA and treY genes were expressed constitutively and that expression was not influenced by the growth phase, suggesting that trehalose accumulation is controlled at the posttranscriptional level or by control of trehalose breakdown rates. Our results indicate that accumulated trehalose plays an important role in protecting R. leguminosarum bv. trifolii cells against desiccation stress and against stress encountered during nodulation.

  10. Say NO to ET.

    Science.gov (United States)

    Vanhoutte, P M

    2000-07-01

    The endothelial cells release both relaxing [nitric oxide (NO), endothelium-derived hyperpolarizing factor (EDHF), prostacyclin] and contracting factors [endoperoxides, thromboxane A(2), superoxide anions, endothelin-1 (ET)]. The production of ET is inhibited by NO. The latter also strongly opposes the direct effects of the former on vascular smooth muscle. With aging and vascular disease, the production of enothelial NO declines, and thus ET can be released, act and contribute to the symptoms.

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

    DEFF Research Database (Denmark)

    Vijn, I; Yang, W C; Pallisgård, N

    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...

  12. 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.

  13. 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...

  14. Draft Genome Sequence of Rhizobium sp. Strain TBD182, an Antagonist of the Plant-Pathogenic Fungus Fusarium oxysporum, Isolated from a Novel Hydroponics System Using Organic Fertilizer

    Science.gov (United States)

    Fujiwara, Kazuki; Someya, Nobutaka; Shinohara, Makoto

    2017-01-01

    ABSTRACT Rhizobium sp. strain TBD182, isolated from a novel hydroponics system, is an antagonistic bacterium that inhibits the mycelial growth of Fusarium oxysporum but does not eliminate the pathogen. We report the draft genome sequence of TBD182, which may contribute to elucidation of the molecular mechanisms of its fungistatic activity. PMID:28302768

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

  16. The lipopolysaccharide lipid-a long chain fatty acid is important for rhizobium leguminosarum growth and stress adaptation in free-living and nodule environments

    Science.gov (United States)

    Rhizobium bacteria live in soil and plant environments, are capable of inducing symbiotic nodules on legumes, invade these nodules, and develop into bacteroids that fix atmospheric nitrogen into ammonium. Lipopolysaccharide (LPS) is anchored in the bacterial outer membrane through a specialized lipi...

  17. Competitive nodulation blocking of cv. Afghanistan pea is related to high levels of nodulation factors made by some strains of Rhizobium leguminosarum bv. viciae

    NARCIS (Netherlands)

    Hogg, B.; Davies, A.E.; Wilson, K.E.; Bisseling, T.; Downie, J.A.

    2002-01-01

    Cultivar Afghanistan peas are resistant to nodulation by many strains of Rhizobium leguminosarum bv. viciae but are nodulated by strain TOM, which carries the host specificity gene nodX. Some strains that lack nodX can inhibit nodulation of cv. Afghanistan by strain TOM. We present evidence that

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

    DEFF Research Database (Denmark)

    Vijn, I; Yang, W C; Pallisgård, N

    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 regio...

  19. Draft Genome Sequence of Rhizobium mesoamericanum STM3625, a Nitrogen-Fixing Symbiont of Mimosa pudica Isolated in French Guiana (South America).

    Science.gov (United States)

    Moulin, Lionel; Mornico, Damien; Melkonian, Rémy; Klonowska, Agnieszka

    2013-01-01

    Rhizobium mesoamericanum STM3625 is a Mimosa pudica symbiont isolated in French Guiana. This strain serves as a model bacterium for comparison of adaptation to mutualism (symbiotic traits, bacterial genetic programs for plant infection) between alpha and beta rhizobial symbionts of Mimosa pudica.

  20. Dogons et Dogon

    OpenAIRE

    Ciarcia, Gaetano

    2006-01-01

    À propos de Anne Doquet, Les masques dogon. Ethnologie savante et ethnologie autochtone, Préface de Sory Camara, Paris, Karthala, 1999, 314 p., bibl., pl., carte (« Hommes et sociétés »), et de Françoise Michel-Jones, Retour aux Dogon. Figures du double et ambivalence, Paris-Montréal, L'Harmattan, 1999, xivÊ+ 157 p., annexe, bibl. (« Connaissance des hommes »). [1re éd., Paris, Le Sycomore, 1978.

  1. Biosynthesis of Rhizobium meliloti lipooligosaccharide Nod factors: NodA is required for an N-acyltransferase activity

    Energy Technology Data Exchange (ETDEWEB)

    Atkinson, E.M.; Long, S.R. (Stanford Univ., CA (United States)); Palcic, M.M.; Hindsgaul, O. (Univ. of Alberta, Edmonton (Canada))

    1994-08-30

    Rhizobium bacteria synthesize N-acylated [beta]-1,4-N-acetylglucosamine lipooligosaccharides, called Nod factors, which act as morphogenic signal molecules to legume roots during development of nitrogen-fixing nodules. The biosynthesis of Nod factors is genetically dependent upon the nodulation (nod) genes, including the common nod genes nodABC. We used the Rhizobium meliloti NodH sulfotransferase to prepare [sup 35]S-labeled oligosaccharides which served as metabolic tracers for Nod enzyme activities. This approach provides a general method for following chitooligosaccharide modifications. We found nodAB-dependent conversion of N-acetylchitotetraose (chitotetraose) monosulfate into hydrophobic compounds which by chromatographic and chemical tests were equivalent to acylated Nod factors. Sequential incubation of labeled intermediates with Escherichia coli containing either NodA or NodB showed that NodB was required before NodA during Nod factor biosynthesis. The acylation activity was sensitive to oligosaccharide chain length, with chitotetraose serving as a better substrate than chitobiose or chitotriose. We constructed a putative Nod factor intermediate, GlcN-[beta]1,4-(GlcNac)[sub 3], by enzymatic synthesis and labeled it by NodH-mediated sulfation to create a specific metabolic probe. Acylation of this oligosaccharide required only NodA. These results confirm previous reports that NodB is an N-deacetylase and suggest that NodA is an N-acyltransferase. 31 refs., 6 figs.

  2. Effect of Rhizobium and Phosphate Solubilizing Bacterial Inoculants on Symbiotic Traits, Nodule Leghemoglobin, and Yield of Chickpea Genotypes

    Directory of Open Access Journals (Sweden)

    G. S. Tagore

    2013-01-01

    Full Text Available A field experiment was carried out during the rabi season of 2004-05 to find out the effect of Rhizobium and phosphate solubilizing bacterial (PSB inoculants on symbiotic traits, nodule leghemoglobin, and yield of five elite genotypes of chickpea. Among the chickpea genotypes, IG-593 performed better in respect of symbiotic parameters including nodule number, nodule fresh weight, nodule dry weight, shoot dry weight, yield attributes and yield. Leghemoglobin content (2.55 mg g−1 of fresh nodule was also higher under IG-593. Among microbial inoculants, the Rhizobium + PSB was found most effective in terms of nodule number (27.66 nodules plant−1, nodule fresh weight (144.90 mg plant−1, nodule dry weight (74.30 mg plant−1, shoot dry weight (11.76 g plant−1, and leghemoglobin content (2.29 mg g−1 of fresh nodule and also showed its positive effect in enhancing all the yield attributing parameters, grain and straw yields.

  3. Rhizobium leguminosarum is the symbiont of lentils in the Middle East and Europe but not in Bangladesh.

    Science.gov (United States)

    Harun-or Rashid, M; Gonzalez, Javier; Young, J Peter W; Wink, Michael

    2014-01-01

    Lentil is the oldest of the crops that have been domesticated in the Fertile Crescent and spread to other regions during the Bronze Age, making it an ideal model to study the evolution of rhizobia associated with crop legumes. Housekeeping and nodulation genes of lentil-nodulating rhizobia from the region where lentil originated (Turkey and Syria) and regions to which lentil was introduced later (Germany and Bangladesh) were analyzed to determine their genetic diversity, population structure, and taxonomic position. There are four different lineages of rhizobia associated with lentil nodulation, of which three are new and endemic to Bangladesh, while Mediterranean and Central European lentil symbionts belong to the Rhizobium leguminosarum lineage. The endemic lentil grex pilosae may have played a significant role in the origin of these new lineages in Bangladesh. The presence of R. leguminosarum with lentil at the center of origin and in countries where lentil was introduced later suggests that R. leguminosarum is the original symbiont of lentil. Lentil seeds may have played a significant role in the initial dispersal of this Rhizobium species within the Middle East and on to other countries. Nodulation gene sequences revealed a high similarity to those of symbiovar viciae.

  4. Aeschynomene evenia, a model plant for studying the molecular genetics of the nod-independent rhizobium-legume symbiosis.

    Science.gov (United States)

    Arrighi, Jean-François; Cartieaux, Fabienne; Brown, Spencer C; Rodier-Goud, Marguerite; Boursot, Marc; Fardoux, Joel; Patrel, Delphine; Gully, Djamel; Fabre, Sandrine; Chaintreuil, Clémence; Giraud, Eric

    2012-07-01

    Research on the nitrogen-fixing symbiosis has been focused, thus far, on two model legumes, Medicago truncatula and Lotus japonicus, which use a sophisticated infection process involving infection thread formation. However, in 25% of the legumes, the bacterial entry occurs more simply in an intercellular fashion. Among them, some Aeschynomene spp. are nodulated by photosynthetic Bradyrhizobium spp. that do not produce Nod factors. This interaction is believed to represent a living testimony of the ancestral state of the rhizobium-legume symbiosis. To decipher the mechanisms of this Nod-independent process, we propose Aeschynomene evenia as a model legume because it presents all the characteristics required for genetic and molecular analysis. It is a short-perennial and autogamous species, with a diploid and relatively small genome (2n=20; 460 Mb/1C). A. evenia 'IRFL6945' is nodulated by the well-characterized photosynthetic Bradyrhizobium sp. strain ORS278 and is efficiently transformed by Agrobacterium rhizogenes. Aeschynomene evenia is genetically homozygous but polymorphic accessions were found. A manual hybridization procedure has been set up, allowing directed crosses. Therefore, it should be relatively straightforward to unravel the molecular determinants of the Nod-independent process in A. evenia. This should shed new light on the evolution of rhizobium-legume symbiosis and could have important agronomic implications.

  5. Effect of Rhizobium Isolates on Isoflavonoid Levels in Chickpea Plants Infected with Fusarium oxysporum f.sp. ciceris

    Directory of Open Access Journals (Sweden)

    A. Arfaoui

    2006-04-01

    Full Text Available The aim of the present studies was to determine the effect of two biocontrol agents, belonging to the genus Rhizobium, PchDMS and Pch43, on the accumulation of soluble phenolic compounds, and particularly constitutive isoflavonoids, in chickpea roots infected with Fusarium oxysporum f. sp. ciceris (Foc, the causal agent of Fusarium wilt of chickpea. Pretreatment of roots with the bacterial isolates before challenge with Foc significantly increased levels of soluble phenolic compounds in both the susceptible ILC482 and the moderately resistant INRAT87/ 1 chickpea cultivars. High performance liquid chromatography analysis revealed the isoflavones biochanin A and formononetin in the chickpea roots, in both the free and the glycosidically bound forms. Bacterization of the roots with Rhizobium isolates before challenge with Foc increased levels of these isoflavones in plant roots. The antifungal activity of crude phenolics extracted from the chickpea roots was tested in vitro on PDA amended with various concentrations of these extracts and inoculated with Foc. Crude phenolics significantly reduced fungal growth and caused considerable morphological changes in the mycelium, including marked cellular disorganization.

  6. High-quality draft genome sequence of Rhizobium mesoamericanum strain STM6155, a Mimosa pudica microsymbiont from New Caledonia.

    Science.gov (United States)

    Klonowska, Agnieszka; López-López, Aline; Moulin, Lionel; Ardley, Julie; Gollagher, Margaret; Marinova, Dora; Tian, Rui; Huntemann, Marcel; Reddy, T B K; Varghese, Neha; Woyke, Tanja; Markowitz, Victor; Ivanova, Natalia; Seshadri, Rekha; Baeshen, Mohamed N; Baeshen, Nabih A; Kyrpides, Nikos; Reeve, Wayne

    2017-01-01

    Rhizobium mesoamericanum STM6155 (INSCD = ATYY01000000) is an aerobic, motile, Gram-negative, non-spore-forming rod that can exist as a soil saprophyte or as an effective nitrogen fixing microsymbiont of the legume Mimosa pudica L.. STM6155 was isolated in 2009 from a nodule of the trap host M. pudica grown in nickel-rich soil collected near Mont Dore, New Caledonia. R. mesoamericanum STM6155 was selected as part of the DOE Joint Genome Institute 2010 Genomic Encyclopedia for Bacteria and Archaea-Root Nodule Bacteria (GEBA-RNB) genome sequencing project. Here we describe the symbiotic properties of R. mesoamericanum STM6155, together with its genome sequence information and annotation. The 6,927,906 bp high-quality draft genome is arranged into 147 scaffolds of 152 contigs containing 6855 protein-coding genes and 71 RNA-only encoding genes. Strain STM6155 forms an ANI clique (ID 2435) with the sequenced R. mesoamericanum strain STM3625, and the nodulation genes are highly conserved in these strains and the type strain of Rhizobium grahamii CCGE501(T). Within the STM6155 genome, we have identified a chr chromate efflux gene cluster of six genes arranged into two putative operons and we postulate that this cluster is important for the survival of STM6155 in ultramafic soils containing high concentrations of chromate.

  7. Rhizobium inoculants: Research progress and development status%根瘤菌菌剂的研究与开发现状

    Institute of Scientific and Technical Information of China (English)

    管凤贞; 邱宏端; 陈济琛; 林新坚

    2012-01-01

    根瘤菌与豆科植物共生成为豆科植物固氮的重要方式,它可以为豆科植物提供所需氮量的1/2 ~1/3.因此,土壤中有效根瘤菌的数量是决定豆科植物产量的重要因素,而根瘤菌菌剂的使用可以有效地提高土壤中根瘤菌数量.本文从根瘤菌菌剂制备中高效菌种的选育及匹配、高密度菌剂的制备、菌剂保存方法等方面进行综述.比较了自然选育、杂交选育和诱变选育等各类选育方法及琼脂试管配对法和水培配对法的优缺点;总结了菌剂制备的一般过程和方法;论述了菌剂保藏过程中冷冻干燥法和各种保护剂的使用对菌剂保藏效果的影响.本文阐述了根瘤菌菌剂的制备工艺和发展方向,为根瘤菌剂的研制提供重要参考.%Rhizobium-Iegumes symbiosis is an important way of legumes nitrogen fixation, which can provide 1/2-1/3 of nitrogen the legumes needed in their whole life. Therefore, the quantity of effective rhizobium in soil is an important decisive factor in legume production, while the use of rhizobium inoculants can effectively increase the quantity of rhizobium in soil. This paper re-viewed the research progress and development status about the breeding and matching of highly effective rhizobium strains and the preparation and preservation of high-density rhizobium inocu-lants , analyzed the advantages and disadvantages of the breeding methods such as natural breed-ing , hybrid breeding, and mutation breeding, the agar matching methods, and the water culture matching methods, and summarized the general process and methods for inoculant preparation. The effects of various freezing-drying methods used in rhizobium inoculant preservation and of the applications of various protective agents on the preservation of rhizobium inoculants were also dis-cussed. This review elaborated the preparation technology and the future development of rhizobi-um inoculants, which could provide a reference for

  8. 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.

  9. Cultures et organisations

    NARCIS (Netherlands)

    Hofstede, G.; Hofstede, G.J.; Minkov, M.

    2010-01-01

    La coopération interculturelle, une question de survie Véritable atlas des valeurs culturelles, paru en 18 langues, Cultures et organisations est le fruit de plus de 40 ans de recherches menées dans plus de 100 pays. Il est aujourd'hui le livre de référence des chercheurs, universitaires et

  10. Et godt brand

    DEFF Research Database (Denmark)

    Christensen, Line Hjorth

    2016-01-01

    leder om Faaborg Museum og Danske Museer i et brandingperspektiv; i anledning af grafisk relancering af tidsskriftet Danske Museer (og nyt brandingprogram for Faaborg Museum, støttet af NCF)......leder om Faaborg Museum og Danske Museer i et brandingperspektiv; i anledning af grafisk relancering af tidsskriftet Danske Museer (og nyt brandingprogram for Faaborg Museum, støttet af NCF)...

  11. Et dansk hotell

    DEFF Research Database (Denmark)

    Baca, Susan; Busck, Ole Gunni

    Rapporten præsenterer resultatet af en undersøgelse af, hvorledes et hotel i Nordjylland fungerer som arbejdsplads for indvandrere af overvejende ikke-vestlig oprindelse. Der fokuseres på i hvilket omfang og gennem hvilke mekanismer arbejdsmiljjøet i bred forstand, herunder forhold i ledelsen...

  12. Cultures et organisations

    NARCIS (Netherlands)

    Hofstede, G.; Hofstede, G.J.; Minkov, M.

    2010-01-01

    La coopération interculturelle, une question de survie Véritable atlas des valeurs culturelles, paru en 18 langues, Cultures et organisations est le fruit de plus de 40 ans de recherches menées dans plus de 100 pays. Il est aujourd'hui le livre de référence des chercheurs, universitaires et professi

  13. Ogunsile et al (18)

    African Journals Online (AJOL)

    USER

    The effects of time and the volume of extract to silver salt solution were investigated on the ... agar well diffusion method. XRD analysis ... attributed to their large surface area to volume ratio (Cho et al., 2005; Mittal et al., 2013). Synthetically ...

  14. Et dansk sykehjem

    DEFF Research Database (Denmark)

    Baca, Susan; Busck, Ole Gunni

    Rapporten præsenterer resultatet af en undersøgelse af, hvorledes et plejehjem i Aalborg kommune fungerer som arbejdsplads for indvandrere af overvejende ikke-vestlig oprindelse. Der fokuseres på i hvilket omfang og gennem hvilke mekanismer arbejdsmiløet i bred forstand, herunder forhold i ledels...

  15. Et Danmark af parallelsamfund

    DEFF Research Database (Denmark)

    v. Freiesleben, Anna Mikaela

    Denne afhandling undersøger et begreb, der hidtil har været et ubeskrevet blad i en dansk forskningsmæssig sammenhæng, begrebet parallelsamfund. I den aktuelle danske politiske og offentlig diskurs tages ’parallelsamfund’ ofte for givet som en betegnelse for segregerede indvandrersamfund (fortrin...

  16. 大豆和花生根瘤菌氢酶的研究%Studies on Hydrogenase from Rhizobium japonicum and Rhizobium arachis

    Institute of Scientific and Technical Information of China (English)

    许良树; 张凤章; 龙敏南; 曾定; 黄河清; 刘月英; 刘广发

    2001-01-01

    根瘤菌在共生固氮过程中因放H2所消耗的能量约占固氮总能量的40%~60%.吸氢酶则能回收和利用固氮过程所放的H2,减少能量损失,从而提高共生固氮效率.在厌氧条件下,加入防止酶蛋白聚合的试剂,利用DEAE-纤维素和SephacrylS-200柱层析,从自养性大豆根瘤菌和花生根瘤菌类菌体中分离并提纯膜结合态氢酶.纯化的两种氢酶表现相近的分子特征:均含有大(60 kD,65kD)、小(30 kD,35 kD)两个亚基;均为NiFe-氢酶,并具有较高的吸H2活性.大豆根瘤菌氢酶的纯酶组分不含Cyt b559.花生根瘤菌L8-3菌株能进行化能自养生长,诱导出高吸H2活性.根瘤菌的吸H2能明显提高固氮活性.从具有高吸H2活性的花生根瘤菌中分离并克隆吸氢基因,采用PCR和探针杂交技术,获得含有吸氢基因的质粒pZ-55.利用多种限制性内切酶构建了质粒pZ-55的物理图谱.通过三亲本杂交,将含吸氢基因的重组质粒转移到不吸H2的花生和毛豆根瘤菌中,所获得的结合株在自生和共生条件下均表达吸H2活性.以结合株接种大田花生,获得的共生根瘤的吸H2活性比接种受体株提高4倍,花生叶片和种子的含N量、产量分别提高1.7%、8.9%和9.6%.%Hydrogen produced by nitrogenase consumed 40~60%0 of energy of symbiotic nitro gen-fixation. Hydrogenase can uptake and reuse the H2 produced by nitrogenase, which results in decreasing the loss of energy and increasing the efficiency of nitrogen fixation. The membranebound hydrogenase from autotrophical cultured Rhizobium japanicum and from the bacteroids of peanut nodule have been purified and characterized. The hydrogenase from R. japonicum consists of two subunits (60 kD, 30 kD). The molecular weight of large and small subunits of hydrogenase from R. arachis is about 65 kD and 35 kD. Both hydrogenases are NiFe-hydrogenase. No cytochrome b(559) could

  17. Tourisme et ressources naturelles

    OpenAIRE

    2016-01-01

    Ce numéro de la Revue Études Caribéennes s’intéresse aux liens qui unissent et opposent l’activité touristique et les ressources naturelles, particulièrement dans les pays du Sud. Dans un contexte de médiatisation accrue des enjeux liés à la biodiversité et aux menaces qui pèsent sur elle, le tourisme – et particulièrement l’écotourisme – est souvent présenté comme un moyen de concilier la conservation et le développement. Les autorités locales, malgré l’existence d’un cadre réglementaire pro...

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

    Science.gov (United States)

    Kim, S A; Copeland, L

    1997-09-01

    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) 1 kDa. The seven amino acids from the N terminus were Lys-Ala-Ser-Ile-Val-Ile-Ala. Thiolysis and condensation activity of the enzyme from free-living CC 1192 cells were optimal at pHs 7.8 and 8.1, respectively. The relationship between substrate concentrations and initial velocity for the thiolysis reaction were hyperbolic and gave K(infm) values for acetoacetyl-CoA and CoA of 42 and 56 (mu)M, respectively. The maximum velocity in the condensation direction was approximately 10% of that of the thiolysis reaction. With highly purified preparations of the enzyme, a value of approximately 1 mM was determined for the apparent K(infm) for acetyl-CoA. However, with partially purified enzyme preparations or when N-ethylmaleimide was included in reaction mixtures the apparent K(infm) for acetyl-CoA was close to 0.3 mM. In the condensation direction, CoA was a potent linear competitive inhibitor with an inhibition constant of 11 (mu)M. The much higher affinity of the enzyme for the product CoA than the substrate acetyl-CoA could have significance in view of metabolic differences between bacteroid and free-living cells of CC 1192. We propose that in free-living CC 1192 cells, the acetyl-CoA/CoA ratio reaches a value that allows condensation activity of acetyl-CoA acetyltransferase, but that in CC 1192 bacteroids, the ratio is poised so that the formation of acetoacetyl-CoA is not favored.

  19. Parler et convaincre

    CERN Document Server

    Vigner, Gérard

    1979-01-01

    Dans l'apprentissage d'une langue, l'échange oral est avant tout utilitaire. On demande un renseignement, un prix, on salue, on remercie... On peut aussi parler pour exposer un point de vue, se justifier, entraîner une décision : parler pour convaincre. Cet ouvrage de la collection OUTILS veut aider les élèves à ce type d'intervention ; il leur fait d'abord analyser la situation de communication dans laquelle ils doivent intervenir, puis trouver les mots et expressions justes et efficaces. Sa structure et ses exercices permettent un travail tant collectif qu'individuel.

  20. TIC et innovation organisationnelle

    OpenAIRE

    Armand, Françoise; Auret, Géraldine; Bachelet, Catherine; Barlette, Yves; Baujard, Corinne; Beeler, Betty; Bonnet, Daniel; Carrere, Frédéric; Choquet, Isabelle; Combaz, Marie-Françoise; Commandré, Monique; Crévits, Igor; Fallery, Bernard; Galey, Béatrice; Labour, Michel

    2013-01-01

    Cet ouvrage rend compte des travaux proposés par des chercheurs et des experts, au cours de la troisième édition des journées d’études du Management des Technologies Organisationnelles, organisées par la Chambre Professionnelle du Conseil Languedoc-Roussillon, le Groupe Sup de Co. Montpellier Business School et l’Ecole des Mines d’Alès les 17 et 18 mars 2011 sur le site de Nîmes de l’Ecole des Mines d’Alès. Ces travaux soulignent l’enjeu du Management des Technologies Organisationnelles pour ...

  1. Microbiologie et maladies infectieuses

    OpenAIRE

    Sansonetti, Philippe

    2014-01-01

    Ce rapport d’activité annuel de la chaire de Microbiologie et maladies infectieuses comprend un rapport sur l’enseignement, un rapport sur la recherche et se conclura par des perspectives concernant ces deux domaines pour l’année académique 2011-2012. Cette chaire veut offrir une vision renouvelée de la microbiologie et des maladies infectieuses en présentant les travaux les plus fondamentaux en microbiologie, le cœur de la discipline, ainsi que sur ses interfaces, particulièrement avec la bi...

  2. Primary protemic study of Rhizobium fredii 042BS%费氏中华根瘤菌042BS(Rhizobium fredii 042BS)蛋白质组学初步研究

    Institute of Scientific and Technical Information of China (English)

    颜廷虎; 白庆武; 李波; 沈世华

    2004-01-01

    为了从蛋白质水平阐明根瘤菌的固氮机理,扩大其宿主植物范围,应用蛋白质组学技术(2-DE),分析比较了能够在大豆和苜蓿上跨宿主结瘤的费氏中华根瘤菌042BS与已经完成基因组测序的根瘤菌模式菌株苜蓿中华根瘤菌(Rhizobium meliloti 1021)的蛋白质表达图谱差异.经过图像分析检测到二者分别有436和428蛋白点.其中约有50个蛋白点初步认为二者所共有的.

  3. Medium Screening and Optimization for Soy Bean Rhizobium (Rhizobium fredii) HH103%大豆根瘤菌HH103菌株培养基的筛选与优化

    Institute of Scientific and Technical Information of China (English)

    肖亦农; 徐琼

    2011-01-01

    Quick-growing soy bean rhizobium (Rhizobium fredii) HH103 was used as a tested strain, and adopted single factor nitrogen source utilization experiment and orthogonal design experiment to confirm the optimum medium and its formula. The results showed that the strain grew well on YMA, the optimum carbon source was sucrose, and the optimum nitrogen was yeast extract with the optimum medium formula as follows (in g/L) : sucrose 11, yeast extract 0.9, K2HPO40.5, MnSO4 0.005, CaCl2 0.1, KH2PO40.5, MgSO40.2, KNO30.77, (NH4)2HPO4 0. 33, FeCl3 0.005, andpH7.2.%以快生型大豆根瘤菌HH103菌株为供试菌株,采用单因素碳氮源利用试验和正交设计试验,确定最佳培养基及其配方.结果表明:该菌株在YMA中生长良好,最佳碳源为蔗糖,最佳氮源为酵母膏,最佳培养基成分配方(g/L):蔗糖11,酵母膏0.9,K2HPO4 0.5,MnSO40.005,CaCl2 0.1,KH2PO4 0.5,MgSO4 0.2,KNO30.77,(NH4)2HPO4 0.33,FeCl3 0.005,pH 7.2.

  4. Ileke et al (5)

    African Journals Online (AJOL)

    big timmy

    extracts of the stem bark are commonly used to treat malaria and ... 2013). Aqueous extracts of the leaf and stem bark ... Ileke et al.: Toxicological and Histopathological Effects of Cheese Wood ..... to reduced production of the metabolic product.

  5. Image et violence

    OpenAIRE

    Nancy, Jean-Luc

    2005-01-01

    Deux affirmations nous sont aujourd’hui familières : celle selon laquelle il y a une violence des images (nous parlons volontiers de « matraquage publicitaire », et la publicité évoque d’abord un déferlement d’images), et celle selon laquelle des images de la violence, de cette violence sans cesse rallumée aux quatre coins du monde, sont omniprésentes et sont, à la fois ou alternativement, indécentes, choquantes, nécessaires, déchirantes. L’une et l’autre affirmation renvoient très vite à l’é...

  6. Hasard et chaos

    CERN Document Server

    Ruelle, David

    1991-01-01

    Comment expliquer le hasard ? Peut-on rendre raison de l'irraisonnable ? Ce livre, où il est question des jeux de dés, des loteries, des billards, des attracteurs étranges, de l'astrologie et des oracles, du temps qu'il fera, du libre arbitre, de la mécanique quantique, de l'écoulement des fluides, du théorème de Gödel et des limites de l'entendement humain, expose les fondements et les conséquences de la théorie du chaos. David Ruelle est membre de l'Académie des sciences et professeur de physique théorique à l'Institut des hautes études scientifiques de Bures-sur-Yvette.

  7. Ismail et al (6)

    African Journals Online (AJOL)

    USER

    ... pumps selection as well as provide necessary information for water, hydraulics, mechanical and .... The analysis of hydraulic and design ... design; Tay et al. ...... Energetical optimization of water ... Wood D J,1981 Algorithms for pipe network.

  8. LYSnET

    DEFF Research Database (Denmark)

    Bønløkke Andersen, Kätte; Hansen, Ellen Katrine; Krogsbæk Mathiasen, Nanet

    2006-01-01

    LYSnET.com skal bidrage til at udbrede og udvikle viden om liv, lys og luft i vores bygninger mellem byggeindustrien, byggeriets uddannelses- og forskningsinstitutioner i Danmark samt andre med interesse for liv, lys og luft.......LYSnET.com skal bidrage til at udbrede og udvikle viden om liv, lys og luft i vores bygninger mellem byggeindustrien, byggeriets uddannelses- og forskningsinstitutioner i Danmark samt andre med interesse for liv, lys og luft....

  9. Ectopia lentis et pupillae

    Directory of Open Access Journals (Sweden)

    Fernanda Marcio

    2011-06-01

    Full Text Available The Ectopia lentis et pupillae is a rare genetic syndrome, congenital, autosomal recessive with variable expression, characterized by ectopia of the lens and the pupil, usually bilateral and symmetrical, but without systemic manifestations. The pathogenesis of this anomaly is still unknown, but there are theories that the change is mesodermal, neuroectodermal, combined or mechanical. This article presents a clinical case of a patient with ectopia lentis et pupillae, describing its clinical and genetic aspects, secondary ocular complications and differential diagnosis.

  10. Effect of Rhizobium and arbuscular mycorrhizal fungi inoculation on electrolyte leakage in Phaseolus vulgaris roots overexpressing RbohB.

    Science.gov (United States)

    Arthikala, Manoj-Kumar; Nava, Noreide; Quinto, Carmen

    2015-01-01

    Respiratory oxidative burst homolog (RBOH)-mediated reactive oxygen species (ROS) regulate a wide range of biological functions in plants. They play a critical role in the symbiosis between legumes and nitrogen-fixing bacteria or arbuscular mycorrhizal (AM) fungi. For instance, overexpression of PvRbohB enhances nodule numbers, but reduces mycorrhizal colonization in Phaseolus vulgaris hairy roots and downregulation has the opposite effect. In the present study, we assessed the effect of both rhizobia and AM fungi on electrolyte leakage in transgenic P. vulgaris roots overexpressing (OE) PvRbohB. We demonstrate that elevated levels of electrolyte leakage in uninoculated PvRbohB-OE transgenic roots were alleviated by either Rhizobium or AM fungi symbiosis, with the latter interaction having the greater effect. These results suggest that symbiont colonization reduces ROS elevated electrolyte leakage in P. vulgaris root cells.

  11. 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, β = 101.48°, and contained one dimeric molecule in the asymmetric unit. It diffracted to 1.79 Å resolution.

  12. Post-transcriptional regulation of NifA expression by Hfq and RNase E complex in Rhizobium leguminosarum bv. viciae

    Institute of Scientific and Technical Information of China (English)

    Yinghua Zhang; Guofan Hong

    2009-01-01

    NifA is the general transcriptional activator of nitrogen fixation genes in diazotrophic bacteria. In Rhizobium leguminosarum by. viciae strain 8401/pRL1JI, the NifA gene is part of a gene cluster (fixABCXNifAB). In this study, results showed that in R. leguminosarum by. viciae 8401/pRLI1I, host factor required (Hfq), and RNase E were involved in the post-transcriptional regulation of NifA expression. It was found that Hfq-dependent RNase E cleavage of NifA mRNA was essen-tial for NifA translation. The cleavage site is located at 32 nucleotides upstream of the NifA translational start codon. A possible explanation based on predicted RNA secondary structure of the NifA 5'-untranslated region was that the cleavage made ribosome-binding sites accessible for translation.

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

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

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

  14. New insights into Nod factor biosynthesis: Analyses of chitooligomers and lipo-chitooligomers of Rhizobium sp. IRBG74 mutants.

    Science.gov (United States)

    Poinsot, Véréna; Crook, Matthew B; Erdn, Stéphanie; Maillet, Fabienne; Bascaules, Adeline; Ané, Jean-Michel

    2016-11-03

    Soil-dwelling, nitrogen-fixing rhizobia signal their presence to legume hosts by secreting lipo-chitooligomers (LCOs) that are decorated with a variety of chemical substituents. It has long been assumed, but never empirically shown, that the LCO backbone is synthesized first by NodC, NodB, and NodA, followed by addition of one or more substituents by other Nod proteins. By analyzing a collection of in-frame deletion mutants of key nod genes in the bacterium Rhizobium sp. IRBG74 by mass spectrometry, we were able to shed light on the possible substitution order of LCO decorations, and we discovered that the prevailing view is probably erroneous. We found that most substituents could be transferred to a short chitin backbone prior to acylation by NodA, which is probably one of the last steps in LCO biosynthesis. The existence of substituted, short chitin oligomers offers new insights into symbiotic plant-microbe signaling.

  15. 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.

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

    Directory of Open Access Journals (Sweden)

    V Bianciotto

    2009-12-01

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

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

    Science.gov (United States)

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

    2001-01-01

    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 affected in extracellular polysaccharides (EPS) have been tested in in vitro adhesion assays and shown to be strongly impaired in the attachment to both types of surfaces as well as to quartz fibers. Anchoring of rhizobacteria to AM fungal structures may have special ecological and biotechnological significance because it may facilitate colonisation of new rhizospheres by the bacteria, and may be an essential trait for the development of mixed inocula.

  18. Iron requirement of Rhizobium leguminosarum and secretion of anthranilic acid during growth on an iron-deficient medium.

    Science.gov (United States)

    Rioux, C R; Jordan, D C; Rattray, J B

    1986-07-01

    Rhizobium leguminosarum GF160 required iron for growth under aerobic conditions in a chemically defined medium. Maximal growth of bacteria previously depleted in iron was obtained with approximately 50 microM unchelated ferric iron and with glucose as the only carbon source. Growth under iron deficiency did not result in the production of detectable levels of siderophores of either the catechol or hydroxamate types. Growing cells released a Fe3+-reducing agent that was identified as anthranilic acid by paper and thin-layer chromatography, ultraviolet and nuclear magnetic resonance spectroscopy, and mass spectrometry. The amount of anthranilic acid secreted per unit of cell growth was inversely related to the iron concentration in the culture medium and reached concentrations up to 1 mM. Ferric but not ferrous ions were solubilized in the growth medium by anthranilic acid.

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

    Science.gov (United States)

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

    2015-01-01

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

  20. 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.

  1. Mutualism and adaptive divergence: co-invasion of a heterogeneous grassland by an exotic legume-rhizobium symbiosis.

    Directory of Open Access Journals (Sweden)

    Stephanie S Porter

    Full Text Available Species interactions play a critical role in biological invasions. For example, exotic plant and microbe mutualists can facilitate each other's spread as they co-invade novel ranges. Environmental context may influence the effect of mutualisms on invasions in heterogeneous environments, however these effects are poorly understood. We examined the mutualism between the legume, Medicago polymorpha, and the rhizobium, Ensifer medicae, which have both invaded California grasslands. Many of these invaded grasslands are composed of a patchwork of harsh serpentine and relatively benign non-serpentine soils. We grew legume genotypes collected from serpentine or non-serpentine soil in both types of soil in combination with rhizobium genotypes from serpentine or non-serpentine soils and in the absence of rhizobia. Legumes invested more strongly in the mutualism in the home soil type and trends in fitness suggested that this ecotypic divergence was adaptive. Serpentine legumes had greater allocation to symbiotic root nodules in serpentine soil than did non-serpentine legumes and non-serpentine legumes had greater allocation to nodules in non-serpentine soil than did serpentine legumes. Therefore, this invasive legume has undergone the rapid evolution of divergence for soil-specific investment in the mutualism. Contrary to theoretical expectations, the mutualism was less beneficial for legumes grown on the stressful serpentine soil than on the non-serpentine soil, possibly due to the inhibitory effects of serpentine on the benefits derived from the interaction. The soil-specific ability to allocate to a robust microbial mutualism may be a critical, and previously overlooked, adaptation for plants adapting to heterogeneous environments during invasion.

  2. NrcR, a New Transcriptional Regulator of Rhizobium tropici CIAT 899 Involved in the Legume Root-Nodule Symbiosis

    Science.gov (United States)

    del Cerro, Pablo; Rolla-Santos, Amanda A. P.; Valderrama-Fernández, Rocío; Gil-Serrano, Antonio; Bellogín, Ramón A.; Gomes, Douglas Fabiano; Pérez-Montaño, Francisco; Megías, Manuel; Hungría, Mariangela; Ollero, Francisco Javier

    2016-01-01

    The establishment of nitrogen-fixing rhizobium-legume symbioses requires a highly complex cascade of events. In this molecular dialogue the bacterial NodD transcriptional regulators in conjunction with plant inducers, mostly flavonoids, are responsible for the biosynthesis and secretion of Nod factors which are key molecules for successful nodulation. Other transcriptional regulators related to the symbiotic process have been identified in rhizobial genomes, including negative regulators such as NolR. Rhizobium tropici CIAT 899 is an important symbiont of common bean (Phaseolus vulgaris L.), and its genome encompasses intriguing features such as five copies of nodD genes, as well as other possible transcriptional regulators including the NolR protein. Here we describe and characterize a new regulatory gene located in the non-symbiotic plasmid pRtrCIAT899c, that shows homology (46% identity) with the nolR gene located in the chromosome of CIAT 899. The mutation of this gene, named nrcR (nolR-like plasmid c Regulator), enhanced motility and exopolysaccharide production in comparison to the wild-type strain. Interestingly, the number and decoration of Nod Factors produced by this mutant were higher than those detected in the wild-type strain, especially under salinity stress. The nrcR mutant showed delayed nodulation and reduced competitiveness with P. vulgaris, and reduction in nodule number and shoot dry weight in both P. vulgaris and Leucaena leucocephala. Moreover, the mutant exhibited reduced capacity to induce the nodC gene in comparison to the wild-type CIAT 899. The finding of a new nod-gene regulator located in a non-symbiotic plasmid may reveal the existence of even more complex mechanisms of regulation of nodulation genes in R. tropici CIAT 899 that may be applicable to other rhizobial species. PMID:27096734

  3. 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.

  4. Paraboles et catastrophes

    CERN Document Server

    Thom, René

    1983-01-01

    René Thom, mathématicien français, membre de l'Académie des Sciences, s'est vu décerner en 1958 la médaille Field, équivalent du Prix Nobel en mathématiques, pour ses créations intellectuelles, la " théorie des catastrophes ", regard nouveau sur toutes les transformations qui adviennent de manière brusque, imprévisible, dramatique. Dans ces entretiens qui vont de la mathématique à l'embryologie, de la linguistique à l'anthropologie et à l'histoire, René Thom expose les grandes lignes de la théorie des catastrophes et passe en revue, avec un esprit à la fois critique et passionné, les grands thèmes scientifiques de notre époque, de la physique atomique à la biologie moléculaire, du " progrès " scientifique et technologique aux connexions complexes entre la société et la science. " Ce petit livre est une extraordinaire réussite en vulgarisation ". (Jean Largeault)

  5. 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.

  6. Increase in osmotolerance of Rhizobium fredii soybean isolate BD32 by the proB proA operon of Escherichia coli.

    Science.gov (United States)

    Neumivakin, L V; Solovjev, V P; Sokhansanj, A; Tilba, V A; Moseiko, N A; Shachbasian, R V; Piruzian, E S

    1995-12-26

    The proB proA operons (which are blocked by the feedback inhibition of proline production) of Escherichia coli wild type or with the mutation proBosm, blocking feedback inhibition effect of proline production, were cloned in a broad host range shuttle vector pVA 12-2. The hybrid plasmids pLVA(proB+A+) and pNSA(proBosm proA), were transferred into a low level osmotolerance Rhizobium fredii strain BD32. Both types of transconjugants were characterised by increased osmotolerance in a minimal medium supplied with 0.4-0.8 M NaCl but in the case of pNSA the effect was more significant. The strain BD32/pNSA had an increased level of intracellular proline concentration. Practical application of the increase in Rhizobium resistance to the stress factors is discussed.

  7. Effect of Rhizobium inoculation on the growth and yield of soybean varieties%大豆接种根瘤菌种植效果研究

    Institute of Scientific and Technical Information of China (English)

    汤复跃; 梁江; 曾维英; 韦清源; 陈文杰; 钟开珍; 陈渊; 李桂珍

    2011-01-01

    [Objective]The effect of Rhizobium inoculation on the growth of soybean has been studied in order to provide foundation for popularization of Rhizobium inoculation technology for soybean production system. [Method]Four major soybean varieties, viz., Guichun 8, Guixia 3, Huachun 6 and Huaxia 3 were planted after inoculation with Rhizobium in Yizhou and Du' an areas of Guangxi. The quantity of Rhizohium and plant fresh weight were investigated at the seedling, branching, flowering, filling and maturity stages in five randomly plants and the yield was recorded at harvest. [Result] Rhizobium inoculation increased soybean yield in the range of 1.06-8.74%. This increase was higher in Guichun 8 in comparison to Huachun 6 in Yizhou and Du' an sites. After inoculation of Rhizobium, both the quantity of Rhizobium and fresh weight of above ground parts increased in different soybean varieties planted in different planting areas. [Conclusion]The results revealed feasibility of Rhizobium inoculation technique for yield increase in soybean, however, selection of suitable Rhizobium species and its compatibility with soybean varieties need to be taken into account, depending on the local entironmental conditions.%[目的]对广西大豆接种根瘤菌种植效果进行研究,为广西大豆生产推广接种根瘤菌提供依据.[方法]在广西宜州和都安大豆产区,以广西主推大豆品种桂春8号、桂夏3号和华南品种华春6号、华夏3号4个大豆品种进行接种根瘤菌种植试验,于苗期、分枝期、开花期、鼓粒期、成熟期取5株长势一致的大豆植株,调查其根瘤数、植株鲜重,并测产.[结果]不同试点的大豆品种接种根瘤菌后,其产量均较未接种根瘤菌的增产1.06%~8.74%,桂春8号在宜州点和都安点接种根瘤菌后较对照增产幅度比华春6号高;大豆接种根瘤菌后,不同品种和不同种植区域的大豆根瘤数均较对照增加,且大豆地上生物产量也增加.[结论

  8. 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...

  9. Zoos et cause animale

    OpenAIRE

    Joulian, Frédéric; Abegg, Christophe

    2013-01-01

    Cet article, rédigé dans un contexte de débats sur les fonctions des zoos, a été repris et actualisé au regard des avancées du terrain et des réformes des zoos. Nous interrogeons les discours des zoos sur un aspect crucial, celui de leur légitimation de l’enfermement d’animaux sauvages, et cela en examinant les différents arguments avancés : conservation d’espèces rares, recherche scientifique, éducation du public. Nous discutons également la question de la réintroduction d’animaux en milieu ...

  10. cancer et techniques innovantes

    OpenAIRE

    2006-01-01

    Tout chirurgien est confronté au cancer à un moment ou à un autre. La connaissance de la cancérologie générale et des bases de la chirurgie oncologique est une nécessité. Si cette spécificité n'est pas reconnue en France, il existe une spécialité de chirurgie oncologique dans plusieurs pays européens. La chirurgie oncologique évolue selon les connaissances de la carcinogénèse, et les thérapeutiques non chirurgicales viennent modifier la place et les modalités de la chirurgie oncologique. La c...

  11. Financiarisation et travail

    OpenAIRE

    Bachet, Daniel; Barnier, Louis-Marie; Bouffartigue, Paul; Boussard, Valérie; Brinkmann, Ulrich; Cardi, François; Chambost, Isabelle; Cihuelo, Jérôme; Cleach, Olivier; de Terssac, Gilbert; Durand, Jean-Pierre; Flocco, Gaëtan; Flottes, Anne; Fortino, Sabine; Gâche, Fabien

    2013-01-01

    Le “Corpus” de ce numéro de La Nouvelle Revue du Travail est consacré aux interdépendances entre la financiarisation de l’économie et les transformations contemporaines du travail. L’entrée privilégiée ici est la gestion, ses acteurs et ses dispositifs, instances intermédiaires grâce auxquelles le macro-économique conforme le microsocial, à travers les métamorphoses imprimées au travail. C’est en particulier autour de l’étude critique des actes désormais omniprésents de mesures physiques et d...

  12. Hvad karakteriserer et talent?

    DEFF Research Database (Denmark)

    Raalskov, Jesper

    2012-01-01

    Debatten i medierne har i stigende grad fokus på talentfulde medarbejdere - men hvad er talent egentlig? I den akademiske litteratur inden for Talent Management (TM) gives der mange forskellige bud på, hvordan man som virksomhed kan udvikle og lede talenter, men færre af feltets inputgivere...... forholder sig til, hvad den overordnede definition af talent er. Der ses i litteraturen divergerende opfattelser af, hvilke konkrete egenskaber (attributter) som definerer et talent. I denne artikel gives et bud på en konsensusskabende tilgang til talent, idet talent kan ses som; det du har gjort (fortid...

  13. Confiance, pouvoir et opportunisme

    Directory of Open Access Journals (Sweden)

    Sébastien Lupo

    2012-12-01

    Full Text Available La maison Garavaque et Cusson fondée en 1759 à Smyrne associe, tant par son capital que par ses régisseurs (à savoir Pierre-Paul Garavaque et Guillaume Cusson, le négociant marseillais Pierre-Honoré Roux à Paul Cusson, entrepreneur de la manufacture royale de Pennautier. La correspondance passive de cette régie montre un commerce d’entrée consistant essentiellement en l’importation de tissus de laine languedociens, les draps s’avérant « aussi nécessaires que le pain » pour l’échelle levantin...

  14. Lipochimie et innovations

    Directory of Open Access Journals (Sweden)

    Alfos Carine

    2003-09-01

    Full Text Available Peut-on parler d’un nouvel âge d’or pour les produits à base de ressources végétales renouvelables et notamment pour les huiles ? Porteurs de performances spécifiques et de caractéristiques plus écologiquement correctes, leur emploi ouvre à l’industrie un potentiel d’innovations auquel participe le département de chimie et rhéologie de l’Iterg. La prise de conscience collective, associée aux évolutions des réglementations françaises et européennes, devrait conduire les industries à prendre de plus en plus en compte le respect de l’environnement dans leurs activités. La substitution de dérivés pétrochimiques par des produits d’origine agricole dans certains secteurs industriels (détergence, lubrifiants, solvants notamment contribue à la protection de notre environnement : diminution des volumes de déchets et des effluents, lutte contre l’effet de serre, moindre écotoxicité, innocuité pour la santé. De plus, l’épuisement latent des ressources pétrolières et la pratique de la jachère ont permis d’accélérer le développement de nouvelles voies de valorisations des huiles végétales et plus largement des agroressources. Les enjeux, à l’horizon 2010, sont bien plus importants encore pour ces produits, qui de part leur fonctionnalité spécifique, ont vocation à continuer d’occuper des marchés de niche. D’ici 10 ans, 2 à 3 millions d’hectares pourraient être consacrés à l’industrie du végétal \\; il s’agit là d’une véritable stratégie de développement durable qui nécessite un soutien politique, une vision à long terme et une motivation forte de l’industrie.

  15. Curriculum scientifique et innovation

    OpenAIRE

    Bonilla, Elisa; Sánchez, Armando; Rojano, Teresa; Chamizo, José Antonio

    2013-01-01

    Dans le cadre de sa réforme de l’éducation, le Mexique a restructuré les programmes de mathématiques et de sciences naturelles. De nouveaux manuels ont été distribués gratuitement aux élèves et aux professeurs. Se basant sur la résolution de problèmes ou la réalisation d’expériences, cette approche des disciplines scientifiques doit favoriser la compréhension par tous de ce qui est essentiel dans l’activité scientifique.

  16. Protestantisme et bonapartisme

    OpenAIRE

    Encrevé, Andre

    2008-01-01

    D’essence autoritaire, le bonapartisme a peu de chance de convenir à ces adeptes du sacerdoce universel que sont les protestants. Toutefois le bonapartisme est issu de la Révolution, il se réclame des principes de 1789, qui ont permis aux protestants de retrouver la liberté et l’égalité, et Bonaparte a donné un statut officiel à leurs Églises. D’où l’attitude complexe, ambiguë des protestants en face du pouvoir bonapartiste. Cependant le cléricalisme dont fait longtemps preuve Napoléon III da...

  17. Potential for plant growth promotion in groundnut (Arachis hypogaea L.) cv. ALR-2 by co-inoculation of sulfur-oxidizing bacteria and Rhizobium.

    Science.gov (United States)

    Anandham, R; Sridar, R; Nalayini, P; Poonguzhali, S; Madhaiyan, M; Sa, Tongmin

    2007-01-01

    The use of Rhizobium inoculant for groundnut is a common practice in India. Also, co-inoculation of Rhizobium with other plant growth-promoting bacteria received considerable attention in legume growth promotion. Hence, in the present study we investigated effects of co-inoculating the sulfur (S)-oxidizing bacterial strains with Rhizobium, a strain that had no S-oxidizing potential in groundnut. Chemolithotrophic S-oxidizing bacterial isolates from different sources by enrichment isolation technique included three autotrophic (LCH, SWA5 and SWA4) and one heterotrophic (SGA6) strains. All the four isolates decreased the pH of the growth medium through oxidation of elemental S to sulfuric acid. Characterization revealed that these isolates tentatively placed into the genus Thiobacillus. Clay-based pellet formulation (2.5 x 10(7) cf ug(-1) pellet) of the Thiobacillus strains were developed and their efficiency to promote plant growth was tested in groundnut under pot culture and field conditions with S-deficit soil. Experiments in pot culture yielded promising results on groundnut increasing the plant biomass, nodule number and dry weight, and pod yield. Co-inoculation of Thiobacillus sp. strain LCH (applied at 60 kg ha(-1)) with Rhizobium under field condition recorded significantly higher nodule number, nodule dry weight and plant biomass 136.9 plant(-1), 740.0mg plant(-1) and 15.0 g plant(-1), respectively, on 80 days after sowing and enhanced the pod yield by 18%. Also inoculation of S-oxidizing bacteria increased the soil available S from 7.4 to 8.43 kg ha(-1). These results suggest that inoculation of S-oxidizing bacteria along with rhizobia results in synergistic interactions promoting the yield and oil content of groundnut, in S-deficit soils.

  18. The Nodulation of Alfalfa by the Acid-Tolerant Rhizobium sp. Strain LPU83 Does Not Require Sulfated Forms of Lipochitooligosaccharide Nodulation Signals▿

    Science.gov (United States)

    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

    2011-01-01

    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-host-range Rhizobium sp. strain LPU83, a bacterium capable of nodulating at least alfalfa, bean, and Leucena leucocephala. The nod gene cluster was located on the plasmid pLPU83b. The organization of the cluster showed synteny with those of the alfalfa-nodulating rhizobia, Sinorhizobium meliloti and Sinorhizobium medicae. Interestingly, the strongest sequence similarity observed was between the partial nod sequences of Rhizobium mongolense USDA 1844 and the corresponding LPU83 nod genes sequences. The phylogenetic analysis of the intergenic region nodEG positions strain LPU83 and the type strain R. mongolense 1844 in the same branch, which indicates that Rhizobium sp. strain LPU83 might represent an early alfalfa-nodulating genotype. The NF chemical structures obtained for the wild-type strain consist of a trimeric, tetrameric, and pentameric chitin backbone that shares some substitutions with both alfalfa- and bean-nodulating rhizobia. Remarkably, while in strain LPU83 most of the NFs were sulfated in their reducing terminal residue, none of the NFs isolated from the nodH mutant LPU83-H were sulfated. The evidence obtained supports the notion that the sulfate decoration of NFs in LPU83 is not necessary for alfalfa nodulation. PMID:20971905

  19. Aspects Technologiques et Developpementaspects Technologiques et Developpement

    Directory of Open Access Journals (Sweden)

    Sebedio Jean-Louis

    2001-07-01

    Full Text Available L’acide linoléique conjugué (CLA est présent dans les aliments d’origine animale, en particulier ceux issus des ruminants. Le CLA peut aussi être synthétisé au laboratoire par isomérisation alcaline de l’acide linoléique. Alors que l’isomère naturel est le 18 : 2 9c,11t, les produits de synthèse contiennent principalement deux isomères, les 18 : 2 9c,11t et 10t,12c. De nombreuses études menées sur des modèles animaux, le plus souvent avec des mélanges synthétiques, montrent des effets potentiellement bénéfiques pour la santé (anticarcinogènes, protecteurs vis-à-vis de l’athérosclérose, modulateurs de la composition corporelle… alors que la plupart des études menées chez l’homme concernent les effets des CLA sur la composition corporelle. À ce jour, les données concernant les effets sur la composition corporelle chez l’homme semblent indiquer un bénéfice potentiel, mais les résultats restent controversés. Par ailleurs, bien qu’un effet anticarcinogène soit démontré chez l’animal, aucune étude chez l’homme n’a pu établir de relation entre CLA et cancer du sein. De plus, peu d’études traitant des aspects sécuritaires liés à la consommation à long terme ont été publiées. Par conséquent, il est nécessaire de disposer de plus de données en particulier chez l’Homme pour garantir l’innocuité de ces acides gras afin de protéger le consommateur, avant d’envisager l’utilisation de CLA dans des aliments fonctionnels.

  20. 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.

  1. Grorum. Et demonstrationsprojekt

    DEFF Research Database (Denmark)

    Traberg-Borup, Steen

    Meddelelsen beskriver udforming og indretning af et grorum opført af fabriksfremstillede komponenter. Alle klimaskærmens dele, dvs. gulv, vægge, loft og dør gennemgås med udførlige bygningstegninger. Desuden beskrives ventilationsanlægget, belysningsanlægget og det specielt udviklede reolsystem....

  2. Landskabskaraktermetoden - et kompendium

    DEFF Research Database (Denmark)

    Caspersen, Ole Hjorth; Nellemann, Vibeke Wainø

    Dette kompendium indeholder en samling af noter om de forskellige trin i den nye danske landskabskaraktermetode, som er udviklet i perioden 2005-05 i et projektsamarbejde mellem Århus og Fyns Amter, Skov- og Naturstyrelsen, Skov og Landskab samt RUC. Projektets formål har været at skabe en...

  3. trajectoire et perspectives

    African Journals Online (AJOL)

    Abdelkader DJEFLAT

    crent la recherche et le capital humain comme facteurs centraux de la croissance .... 3 A ce titre, il faut rappeler le classement de l'Algérie sur le Global Innovation Index ...... Nations », Economica, Paris. ... pment and Cultural Change, 18: 1-24.

  4. ahadzie et al

    African Journals Online (AJOL)

    PUBLICATIONS1

    3Department of Computer Science, KNUST, Kumasi ... competencies relating to achieving the standard ... Brill et al., (2006) using a web- ... practical application of the core competencies .... culties and delays, poor coordination and com- ..... for subjective judgment and hence creating .... Ghana (Technical Document). Accra ...

  5. Aderoju et al (18)

    African Journals Online (AJOL)

    USER

    The digital aeromagnetic data were processed to produce total magnetic intensity and .... filters to TMI-RTE data as outlined by Stone et al. (2004). ... 2D-forward modeling of some ... primarily an image-based recognition of patterns, trends ...

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

    Directory of Open Access Journals (Sweden)

    Antonio Roberto Giardini

    1985-01-01

    Full Text Available Existe, nas nossas condições, uma população autóctone de Rhizobium capaz de nodular o amendoim (Arachis hypogaea L., mas pouco se sabe da contribuição do nitrogênio fixado para esta planta. Foram conduzidos dois ensaios no campo, em solo de baixa fertilidade, um no período "da seca" e outro no "das águas", comparando o crescimento e a produção de plantas de amendoim inoculado com Rhizobium selecionado, com o de plantas noduladas pela população autóctone, adubadas ou não com nitrogênio. A nodulação das plantas inoculadas foi semelhante à observada nos tratamentos não inoculados, com ou sem nitrogênio. Na fase final do ciclo das plantas, houve maior acúmulo e maior taxa de absorção diária de nitrogênio nos tratamentos inoculados ou com adubação nitrogenada, do que no controle sem inoculação e sem nitrogênio. No ensaio da seca, não houve aumento de produção devido à adubação nitrogenada, ou à inoculação. No ensaio das águas, houve resposta à aplicação de nitrogênio no plantio. Os resultados de produção não foram coerentes com os da marcha de absorção de N. A produção de ensaio das águas foi equivalente a 3.400 kg/ha para o tratamento sem nitrogênio e sem inoculação.Two field experiments were carried out with peanut in the same area on a limed and fertilized "cerrado soil" (originally acidic and low fertility. The first experiment was carried out in the autumn/winter (dry season, and the second one in the subsequent spring/summer (wet season, in Campinas, State of São Paulo, Brazil. Plant development and production of inoculated (three Rhizobium strains and nitrogen fertilized treatments (at planting 25 and 45 days after planting were compared with non-inoculated and non-N-fertilized control. Nodulation of inoculated plants was similar to those of non-inoculated, with or without nitrogen. Greater accumulations, and rates for average daily uptake of nitrogen were observed for inoculated as

  7. Thermodynamique et physique statistique

    CERN Document Server

    Jancovici, Bernard

    1996-01-01

    Cet ouvrage donne une présentation unifiée de la thermodynamique et de la physique statistique. Au point de vue historique, la thermodynamique macroscopique a précédé la physique statistique qui adopte, elle, un point de vue microscopique. Des concepts tels que chaleur, énergie interne, entropie, introduits sans interprétation microscopique, peuvent paraître trop abstraits et rebuter un débutant. Ici, on a préféré donner des notions simples sur la physique statistique (c'est-à-dire se placer à l'échelle atomique) pour en déduire les principes de la thermodynamique.

  8. Cyrano et les hydropotes

    Directory of Open Access Journals (Sweden)

    Alain Mothu

    2007-10-01

    Full Text Available « Car il sera grand devant le Seigneur. Il ne boira ni vin, ni liqueur enivrante, et il sera rempli de l’Esprit-Saint dès le sein de sa mère »(Luc, I, 15Cyrano dédie sa lettre à la gloire de l’aqueduc d’Arcueil et des fontaines parisiennes qu’il alimentait, à « (ses amis les buveurs d’eau ». Cette dédicace abrite peut-être une fine allusion au fait que la construction de l’« acqueduc Médicis », entamée en 1612, fut financée en partie par un droit d’entrée à Paris imposé sur les vins, comme ...

  9. Cyberespace et cyberculture

    Directory of Open Access Journals (Sweden)

    Pierre Lévy

    1998-03-01

    Full Text Available Alors, pendant la petite heure que va durer cette conférence, je voudrais partager avec vous quelques réflexions et quelques hypothèses sur la Cyberculture. Je voudrais d'abord situer les choses, mon propos est un propos de philosophe, autrement dit, il va s'agir de spéculations sur des concepts. Donc, je vous avertis tout de suite à quelle sauce vous allez être mangés. Il ne s'agit pas d'un discours culturel critique, comme les intellectuels français en ont l'habitude, et il ne s'agit pas non plus de grandes prédictions sur le XXIème siècle, il s'agit vraiment d'une réflexion un peu approfondie sur des concepts.

  10. Cyberespace et cyberculture

    Directory of Open Access Journals (Sweden)

    Pierre Lévy

    1999-01-01

    Full Text Available Alors, pendant la petite heure que va durer cette conférence, je voudrais partager avec vous quelques réflexions et quelques hypothèses sur la Cyberculture. Je voudrais d'abord situer les choses, mon propos est un propos de philosophe, autrement dit, il va s'agir de spéculations sur des concepts. Donc, je vous avertis tout de suite à quelle sauce vous allez être mangés. Il ne s'agit pas d'un discours culturel critique, comme les intellectuels français en ont l'habitude, et il ne s'agit pas non plus de grandes prédictions sur le XXIème siècle, il s'agit vraiment d'une réflexion un peu approfondie sur des concepts.

  11. Gestion et mondialisation

    Directory of Open Access Journals (Sweden)

    Jean-Luc Metzger

    2010-10-01

    Full Text Available L’économie mondiale est en crise. Apparue dans la sphère financière globalisée, cette « crise » se serait propagée à l’économie réelle planétaire, laquelle, pour s’adapter, exige des élites politiques qu’elles interviennent et encouragent la mise en œuvre d’instruments de gestion portant sur l’emploi, l’organisation du travail ou les relations avec les différents marchés (clients et fournisseurs. Une telle vision, dominante, naturalise la production des dynamiques contemporaines. Elle présen...

  12. Comique et pyrotechnie

    OpenAIRE

    Feindt, Hendrik

    2008-01-01

    Le feu d'artifice qui se déroule à la fin des Vacances de Monsieur Hulot compte parmi les plus frustrants de l'histoire du cinéma. Il éclate prématurément. Sa chorégraphie se déploie dans une incoordination totale. Et dans l'absence, puisque son public est plongé dans le sommeil. Le son même est parasité par des bruits de tirs, de canonnades et de bombardements qui tirent le spectacle vers le registre guerrier. Cette congruence dissonante (ou encore ce « relief moral », dirait André Bazin) su...

  13. Management et reconnaissance

    OpenAIRE

    Aktouf,Omar

    2016-01-01

    S’interrogeant à propos d’une des toutes récentes « modes » de mobilisation des « ressources humaines » en management, celle dite du « management par la reconnaissance », l’auteur tente de montrer comment bien des contradictions interdisent encore l’accès à une véritable et authentique implication de l’employé dans ce qu’il fait pour son entreprise. L’une de ces contradictions, et non des moindres, réside dans ce qu’il présente comme une incompatibilité originelle entre les visées traditionne...

  14. Management et reconnaissance

    OpenAIRE

    Aktouf,Omar

    2016-01-01

    S’interrogeant à propos d’une des toutes récentes « modes » de mobilisation des « ressources humaines » en management, celle dite du « management par la reconnaissance », l’auteur tente de montrer comment bien des contradictions interdisent encore l’accès à une véritable et authentique implication de l’employé dans ce qu’il fait pour son entreprise. L’une de ces contradictions, et non des moindres, réside dans ce qu’il présente comme une incompatibilité originelle entre les visées traditionne...

  15. Et bedre image

    DEFF Research Database (Denmark)

    Vestergaard, Hedvig; Haagerup, Christian Deichmann

    2010-01-01

    Pjecen sammenfatter erfaringer og råd om, hvordan man kan tage fat på at forbedre et boligområdes image. Det er erfaringer og råd som aktører og ledere fra Bispehaven i Århus Kommune, Vejleåparken i Ishøj Kommune og Tingbjerg i Københavns Kommune gerne vil give videre til andre, der skal i gang med...... imageforbedrende indsatser. De tre områder har arbejdet på at forbedre omdømmet og få et bedre image indadtil og udadtil i forbindelse med større renoveringsindsatser i perioden 2002-2009. Hertil kommer optimering af organisationen og organisationskulturen for at nå bedre resultater. Indsatserne i områderne viser...

  16. Conclusion et discussion

    OpenAIRE

    Bertrand, Romain; Wachtel, Nathan; Berger, Laurent; Levi, Giovanni; Boucheron, Patrick; Calvo, Thomas

    2016-01-01

    M. Romain BERTRANDNous voilà désormais rendus au terme probablement très provisoire concernant les débats et les discussions des travaux de Nathan WACHTEL lors de cette rencontre. Il nous reste une trentaine de minutes pour engager le débat avec les participants de la dernière séance et, le cas échéant, faire valoir des remarques générales sur telle ou telle session. Je souhaiterais inviter Nathan WACHTEL à initier cet échange s’il le souhaite. M. Nathan WACHTELComme je l’expliquais à Romain,...

  17. Femmes, militance et vieillissement

    Directory of Open Access Journals (Sweden)

    Anne Quéniart

    2008-09-01

    Full Text Available Cet article se propose d’aborder la question de la militance chez les femmes aînées à partir des résultats d’une recherche qualitative menée au Québec, Canada, sur trois ans (2005-2008. Alors que les aînées d’aujourd’hui appartiennent à une génération de femmes qui ont ouvert de multiples portes et ont investi de nouveaux espaces publics, on s’est peu intéressé à leurs pratiques et au sens de leurs engagements après 65 ans. Après avoir introduit la question de la participation sociale et citoyenne des personnes âgées en général, et plus particulièrement des femmes âgées, les auteures mettent en évidence les principales caractéristiques de leurs engagements militants et de leurs conceptions du monde ; un monde qu’elles rêvent encore de changer. Une attention particulière est portée à la perception qu’ont les aînées des différences liées au genre et à la génération. En effet, bien que la plupart d’entre elles ne se définissent pas comme étant des retraitées ni des féministes, elles considèrent que leurs formes et leurs pratiques de militance se distinguent de celles des jeunes militantes et de leurs homologues masculins.Este artículo tiene como objetivo analizar la cuestión de la militancia de las mujeres mayores de 65 años. Propone un estudio llevado a cabo en Québec, Canadá, sobre un período de 3 años (2005-2008. Sabemos que las mujeres mayores de 65 años pertenecen a una nueva generación que ha abierto muchas puertas y se ha introducido en espacios públicos nuevos. Sin embargo, poco nos hemos interesado por sus actividades y sus compromisos después de los 65 años. En este estudio, se introducirá de forma general el problema de la participación social y ciudadana de las personas mayores para después comprobar las principales características de su militancia y de su concepción del mundo. Se prestará especial atención a la percepción que tienen estas mujeres de las

  18. Hospice, et levende hus

    DEFF Research Database (Denmark)

    Steenfeldt, Vibeke Østergaard

    Det er formålet med afhandlingen Hospice – et levende hus. En analyse af levet liv og omsorg på hospice som bidrag til forståelse af åndelig omsorg at skabe vi¬den om den oplevelse det uhelbredeligt syge menneske, der tilbringer den sidste del af livet på et hospice, har af omsorgspraksis og levet...... liv på hospice, og at bidrage til udvik¬ling af en ny forståelse af åndelig omsorg som sygeplejefagligt begreb. Undersøgelsen, der har en livsverdensfænomenologisk tilgang, gennem¬føres som et etnografisk feltstudie. I en periode på otte måneder, hvor jeg har været deltagende observatør på to hospicer......, der i første om¬gang er udført uden teoretisk indblanding og efterfølgende perspektiveret ved inddragelse af Medard Boss’ daseinsanalytiske tilgang til forståelse af menne¬ske og krop, sundhed og sygdom og af Kari Martinsens omsorgstænkning. Analysen viser, at den uhelbredeligt syge patient på hospice...

  19. Candide et le physicien

    CERN Document Server

    Espagnat, Bernard d'

    2008-01-01

    Les avancées considérables de la physique d'après guerre n'ont - on le sait - été possibles qu'au prix d'une vraie rupture entre elle et la physique dite " classique ". A quels changements cette rupture nous contraint-elle en ce qui concerne des notions essentielles, telles celles d'espace, de temps, d'objet et d'objectivité ? Quelles en sont les incidences quant à la portée de la connaissance, au rôle de la conscience, aux relations entre science et ontologie ? Ce sont là des questions de fond, fort délicates, auxquelles les personnes de tendance quelque peu philosophique sont plus sensibles que ne le sont les physiciens. Malheureusement, les premières ne disposent normalement pas des connaissances de pointe qui seules permettent d'approfondir de tels problèmes sans trop risquer de s'égarer. Etant donné l'impact que, par ses applications, la science a sur nos vies, nombreux sont ceux qui souhaitent se former une idée plus juste de ce qu'elle implique vraiment. Le présent ouvrage prend la for...

  20. Ledelse i et interventionsperspektiv

    DEFF Research Database (Denmark)

    Keiding, Tina Bering

    2012-01-01

    kapitel vil koncentrere sig om, hvorledes ledelse kan gribes an under hensyntagen til begge vilkår: at ledelseskommunikation vil og skal intervenere og at den ikke kan gribe direkte ind i de ledelsesudsatte systemer. Fokus ligger på forandring af sociale systemer, hvad enten det er hele organisationen, en...... afdeling, et team eller en gruppe. Ledelse handler i høj grad om intervention i sociale systemer (organisationer, afdelinger, teams, grupper mv.), og da sociale systemer ikke forandres gennem forandring af enkeltpersoner, men gennem forandring af kommunikation. Ledelse kan naturligvis også rette sig mod...

  1. Populisme et politique

    OpenAIRE

    Ivekovic, Rada

    2009-01-01

    A propos de : Ernesto Laclau, La Raison populiste, Paris, Le Seuil, 2008 (trad. de l’anglais par J.-P. Ricard ; titre original : On Populist Reason). Ernesto Laclau, Chantal Mouffe, Hégémonie et stratégie socialiste. Vers une politique démocratique radicale (préface d’Etienne Balibar), Paris, Les Solitaires intempestifs, 2009 (trad. de l’anglais par J. Abriel ; titre original : Hegemony and Socialist Strategy : Towards a Radical Democratic Politics, Londres, Verso, 1985) Autre livres mention...

  2. Characterisation of SalRAB a salicylic acid inducible positively regulated efflux system of Rhizobium leguminosarum bv viciae 3841.

    Science.gov (United States)

    Tett, Adrian J; Karunakaran, Ramakrishnan; Poole, Philip S

    2014-01-01

    Salicylic acid is an important signalling molecule in plant-microbe defence and symbiosis. We analysed the transcriptional responses of the nitrogen fixing plant symbiont, Rhizobium leguminosarum bv viciae 3841 to salicylic acid. Two MFS-type multicomponent efflux systems were induced in response to salicylic acid, rmrAB and the hitherto undescribed system salRAB. Based on sequence similarity salA and salB encode a membrane fusion and inner membrane protein respectively. salAB are positively regulated by the LysR regulator SalR. Disruption of salA significantly increased the sensitivity of the mutant to salicylic acid, while disruption of rmrA did not. A salA/rmrA double mutation did not have increased sensitivity relative to the salA mutant. Pea plants nodulated by salA or rmrA strains did not have altered nodule number or nitrogen fixation rates, consistent with weak expression of salA in the rhizosphere and in nodule bacteria. However, BLAST analysis revealed seventeen putative efflux systems in Rlv3841 and several of these were highly differentially expressed during rhizosphere colonisation, host infection and bacteroid differentiation. This suggests they have an integral role in symbiosis with host plants.

  3. Relevance of fucose-rich extracellular polysaccharides produced by Rhizobium sullae strains nodulating Hedysarum coronarium l. legumes.

    Science.gov (United States)

    Gharzouli, Razika; Carpéné, Marie-Anne; Couderc, François; Benguedouar, Ammar; Poinsot, Véréna

    2013-03-01

    Specific and complex interactions between soil bacteria, known as rhizobia, and their leguminous host plants result in the development of root nodules. This process implies a complex dialogue between the partners. Rhizobia synthesize different classes of polysaccharides: exopolysaccharides (EPS), Kdo-rich capsular polysaccharides, lipopolysaccharides, and cyclic β-(1,2)-glucans. These polymers are actors of a successful symbiosis with legumes. We focus here on studying the EPS produced by Rhizobium sullae bacteria that nodulate Hedysarum coronarium L., largely distributed in Algeria. We describe the influence of the carbon source on the production and on the composition of EPS produced by R. sullae A6 and RHF strains. High-molecular-weight EPS preserve the bacteria from desiccation. The structural characterization of the EPS produced by R. sullae strains has been performed through sugar analysis by gas chromatography-mass spectrometry. The low-molecular-weight EPS of one strain (RHF) has been totally elucidated using nuclear magnetic resonance and quantitative time-of-flight tandem mass spectrometry analyses. An unusual fucose-rich EPS has been characterized. The presence of this deoxy sugar seems to be related to nodulation capacity.

  4. 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.

  5. Light regulates attachment, exopolysaccharide production, and nodulation in Rhizobium leguminosarum through a LOV-histidine kinase photoreceptor.

    Science.gov (United States)

    Bonomi, Hernán R; Posadas, Diana M; Paris, Gastón; Carrica, Mariela del Carmen; Frederickson, Marcus; Pietrasanta, Lía Isabel; Bogomolni, Roberto A; Zorreguieta, Angeles; Goldbaum, Fernando A

    2012-07-24

    Rhizobium leguminosarum is a soil bacterium that infects root hairs and induces the formation of nitrogen-fixing nodules on leguminous plants. Light, oxygen, and voltage (LOV)-domain proteins are blue-light receptors found in higher plants and many algae, fungi, and bacteria. The genome of R. leguminosarum bv. viciae 3841, a pea-nodulating endosymbiont, encodes a sensor histidine kinase containing a LOV domain at the N-terminal end (R-LOV-HK). R-LOV-HK has a typical LOV domain absorption spectrum with broad bands in the blue and UV-A regions and shows a truncated photocycle. Here we show that the R-LOV-HK protein regulates attachment to an abiotic surface and production of flagellar proteins and exopolysaccharide in response to light. Also, illumination of bacterial cultures before inoculation of pea roots increases the number of nodules per plant and the number of intranodular bacteroids. The effects of light on nodulation are dependent on a functional lov gene. The results presented in this work suggest that light, sensed by R-LOV-HK, is an important environmental factor that controls adaptive responses and the symbiotic efficiency of R. leguminosarum.

  6. Genetic diversity of indigenous Rhizobium leguminosarum bv. viciae isolates nodulating two different host plants during soil restoration with alfalfa.

    Science.gov (United States)

    Zhang, X X; Kosier, B; Priefer, U B

    2001-09-01

    A total of 360 Rhizobium leguminosarum bv. viciae strains was isolated from three brown-coal mining restoration fields of different age and plant cover (without and in the first and second year of alfalfa, Medicago sativa, cultivation) using two host species (Vicia hirsuta and Pisum sativum) as capture plants. The strains were genetically typed by restriction fragment length polymorphism analysis of polymerase chain reaction (PCR)-generated 16S-23S ribosomal DNA intergenic spacer regions (IGS-RFLP) and characterized by plasmid profiles and RFLP analysis of amplified nodABC genes. The R. leguminosarum bv. viciae population was dominated by the same group of strains (irrespective of the trap plant used). According to type richness, the genetic diversity of indigenous R. leguminosarum in the second year of restoration was lower than in the first year and it resembled that of the fallow field, except for plasmid types, in which it was higher than that of the fallow field. Some of the less frequent nodABC genotypes were associated with distinct chromosomal IGS genotypes and symbiotic plasmids (pSyms) of different sizes, indicating that horizontal transfer and rearrangements of pSym can occur in natural environments. However, the dominant pSym and chromosomal genotypes were strictly correlated suggesting a genetically stable persistence of the prevailing R. leguminosarum bv. viciae genotypes in the absence of its host plant.

  7. Multiplicity of Sulfate and Molybdate Transporters and Their Role in Nitrogen Fixation in Rhizobium leguminosarum bv. viciae Rlv3841.

    Science.gov (United States)

    Cheng, Guojun; Karunakaran, Ramakrishnan; East, Alison K; Poole, Philip S

    2016-02-01

    Rhizobium leguminosarum Rlv3841 contains at least three sulfate transporters, i.e., SulABCD, SulP1 and SulP2, and a single molybdate transporter, ModABC. SulABCD is a high-affinity transporter whose mutation prevented growth on a limiting sulfate concentration, while SulP1 and SulP2 appear to be low-affinity sulfate transporters. ModABC is the sole high-affinity molybdate transport system and is essential for growth with NO3(-) as a nitrogen source on limiting levels of molybdate (molybdate, a quadruple mutant with all four transporters inactivated, had the longest lag phase on NO3(-), suggesting these systems all make some contribution to molybdate transport. Growth of Rlv3841 on limiting levels of sulfate increased sulB, sulP1, modB, and sulP2 expression 313.3-, 114.7-, 6.2-, and 4.0-fold, respectively, while molybdate starvation increased only modB expression (three- to 7.5-fold). When grown in high-sulfate but not low-sulfate medium, pea plants inoculated with LMB695 (modB) reduced acetylene at only 14% of the wild-type rate, and this was not further reduced in the quadruple mutant. Overall, while modB is crucial to nitrogen fixation at limiting molybdate levels in the presence of sulfate, there is an unidentified molybdate transporter also capable of sulfate transport.

  8. Characterisation of SalRAB a salicylic acid inducible positively regulated efflux system of Rhizobium leguminosarum bv viciae 3841.

    Directory of Open Access Journals (Sweden)

    Adrian J Tett

    Full Text Available Salicylic acid is an important signalling molecule in plant-microbe defence and symbiosis. We analysed the transcriptional responses of the nitrogen fixing plant symbiont, Rhizobium leguminosarum bv viciae 3841 to salicylic acid. Two MFS-type multicomponent efflux systems were induced in response to salicylic acid, rmrAB and the hitherto undescribed system salRAB. Based on sequence similarity salA and salB encode a membrane fusion and inner membrane protein respectively. salAB are positively regulated by the LysR regulator SalR. Disruption of salA significantly increased the sensitivity of the mutant to salicylic acid, while disruption of rmrA did not. A salA/rmrA double mutation did not have increased sensitivity relative to the salA mutant. Pea plants nodulated by salA or rmrA strains did not have altered nodule number or nitrogen fixation rates, consistent with weak expression of salA in the rhizosphere and in nodule bacteria. However, BLAST analysis revealed seventeen putative efflux systems in Rlv3841 and several of these were highly differentially expressed during rhizosphere colonisation, host infection and bacteroid differentiation. This suggests they have an integral role in symbiosis with host plants.

  9. Identification of a NodD repressible gene adjacent to nodM in Rhizobium leguminosarum biovar viciae

    Institute of Scientific and Technical Information of China (English)

    Xiao'er Yang; Bihe Hou; Chenzhi Zong; Guofan Hong

    2012-01-01

    The nodFEL and nodMNT operons in Rhizobium leguminosarum biovar viciae are transcribed in the same orie-tation and induced by NodD in response to flavonoids secreted by legumes.In the narrow intergenic region between nodFEL and nodMNT,we identified a small gene divergently transcribed from nodM to the 3' end of nodL.Unlike the promoters upstream of nodF and nodM,the promoter of this gene is constitutively expressed.It appeared that its promoter might partially overlap with that of nodM and its expression was repressed by nodD.A deletion mutation was made and proteins produced by the mutant were compared with those by wild-type using 2D gel electrophoresis.Several protein differences were identified suggesting that this small gene influences the expression or stability of these proteins.However,the mutant nodulated its host plant (pea) normally.

  10. 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.

  11. Flocculating Properties and Production of the Compound Bioflocculant by Rhizobium Radiobacter F2 and Bacillus Sphaeicus F6

    Institute of Scientific and Technical Information of China (English)

    Lixin Li; Lingyan Feng; Fang Ma; Qianshen Zhao

    2015-01-01

    A compound bioflocculant CBF, produced by mixed culture of Rhizobium radiobacter F2 and Bacillus sphaeicus F6, was investigated with regard to its production and flocculating properties. The optimization of the culture medium constituents including carbon source, nitrogen source and C/N ratio, metal ions and ionic strength on CBF production were studied. Flocculating properties of CBF were examined by a series of experiments and CBF had good flocculating activities in kaolin suspension with divalent cations and stable over wide range of pH. Studies of the flocculating properties revealed that the flocculation could be stimulated by cations Ca2+, Mg2+, Fe2+, Al3+and Fe3+. In addition, it was stable at 4-30℃ in the presence of CaCl2 . It was found to be effective for flocculation of a kaolin suspension under neutral and weak alkaline conditions ( pH 7�0-9�0 ) , and flocculating activities of higher than 95% were obtained when the CBF concentrations among 6-14 mg/L at pH 8�0. The results of this study indicate that CBF is a potential replacement of conventional synthetic flocculants and is widely applied in water treatment and downstream processing of food and fermentation industries.

  12. Change in morphological properties of root and aerial parts of chickpea under drought stress, arbuscular mycorrhizal fungi and rhizobium treatments

    Directory of Open Access Journals (Sweden)

    S. Morad

    2016-09-01

    Full Text Available To evaluate the effect of arbuscular mycorrhizal (AM fungi (Glomus mosseae and Glomus intraradices and Mesorhizobium Ciceri bacteria at three soil moisture levels [28% (field capacity, FC, 15% (-5 bar suction and 9% (-10 bar tension by weight] on morphological properties of root and aerial parts of chickpea, a greenhouse factorial experiment, arranged as a complete randomized design, was conducted in a sterilized soil. Results showed that moisture treatment had significance effect on number of pods, number of seeds, fresh and dry weight of root and aerial parts, plant height and root length and volume. Application of Mesorhizobium was effective on number of nodes, number of pods, number of seeds, fresh and dry weight of root and aerial parts, plant height, root length and volume. Glomus mosseae had significant effect on plant height. Interaction of moisture and AM fungi was significant on fresh and dry weight of root and aerial parts. Interaction effect of Mesorhizobium and soil moisture was only significant on number of nodes. In general, the highest fresh and dry weight of aerial parts (44.6 and 10.53 grams, respectively was obtained by inoculation of chickpea by rhizobium bacteria and Glomus mosseae at FC moisture level, and AM fungi Glomus mosseae was more efficient compared to Glomus intraradices in both drought stress and without stress conditions.

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

    Science.gov (United States)

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

    2015-01-01

    Rhizobium sullae strain WSM1592 is an aerobic, Gram-negative, non-spore-forming rod that was isolated from an effective nitrogen (N2) fixing root nodule formed on the short-lived perennial legume Hedysarum coronarium (also known as Sulla coronaria or Sulla). WSM1592 was isolated from a nodule recovered from H. coronarium roots located in Ottava, bordering Sassari, Sardinia in 1995. WSM1592 is highly effective at fixing nitrogen with H. coronarium, and is currently the commercial Sulla inoculant strain in Australia. Here we describe the features of R. sullae strain WSM1592, together with genome sequence information and its annotation. The 7,530,820 bp high-quality permanent draft genome is arranged into 118 scaffolds of 118 contigs containing 7.453 protein-coding genes and 73 RNA-only encoding genes. This rhizobial genome is sequenced as part of the DOE Joint Genome Institute 2010 Genomic Encyclopedia for Bacteria and Archaea-Root Nodule Bacteria (GEBA-RNB) project.

  14. Genetic diversity of indigenous Rhizobium leguminosarum bv. viciae isolates nodulating two different host plants during soil restoration with alfalfa

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, X.X.; Kosier, B.; Priefer, U.B. [Rheinisch-Westfaelische TH Aachen, Aachen (Germany)

    2001-09-01

    A total of 360 Rhizobium leguminosarum bv. viciae strains was isolated from three brown-coal mining restoration fields of different age and plant cover (without and in the first and second year of alfalfa, Medicago sativa, cultivation) using two host species (Vicia hirsuta and Pisum sativum) as capture plants. The strains were genetically typed by restriction fragment length polymorphism analysis of polymerase chain reaction (PCR)-generated 16S-23S ribosomal DNA intergenic spacer regions (IGS-RFLP) and characterized by plasmid profiles and RFLP analysis of amplified nodABC genes. The R. leguminosarum bv. viciae population was dominated by the same group of strains (irrespective of the trap plant used). According to type richness, the genetic diversity of indigenous R. leguminosarum in the second year of restoration was lower than in the first year and it resembled that of the fallow field, except for plasmid types, in which it was higher than that of the fallow field. Some of the less frequent nodABC genotypes were associated with distinct chromosomal IGS genotypes and symbiotic plasmids (pSyms) of different sizes, indicating that horizontal transfer and rearrangements of pSym can occur in natural environments. However, the dominant pSym and chromosomal genotypes were strictly correlated suggesting a genetically stable persistence of the prevailing R. leguminosarum bv, viciae genotypes in the absence of its host plant.

  15. 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.

  16. Transgenic Leucaena leucocephala expressing the Rhizobium gene pydA encoding a meta-cleavage dioxygenase shows reduced mimosine content.

    Science.gov (United States)

    Jube, Sandro L R; Borthakur, Dulal

    2010-04-01

    The use of the tree-legume Leucaena leucocephala (leucaena), which contains high levels of proteins in its foliage, is limited due to the presence of the toxic free amino acid mimosine. The goal of this research was to develop transgenic leucaena with reduced mimosine content. Two genes, pydA and pydB, encoding a meta-cleavage dioxygenase (EC 1.13.11.2) and a pyruvate hydrolase (EC 3.7.1.6), respectively, from the mimosine-degrading leucaena symbiont Rhizobium sp. strain TAL1145, were used to transform leucaena. These bacterial genes were sequence-optimized for expression in leucaena and cloned into the plant binary vector pCAMBIA3201 for Agrobacterium tumefaciens-mediated transformation. Using immature zygotic embryos as the start explant material, six pydA and three pydB transgenic lines were developed. The presence and expression of the bacterial genes in the transgenic lines were verified by PCR, reverse transcriptase PCR, and Southern analyses. HPLC analyses of the transgenic plants determined that the mimosine contents of the pydA-expressing lines were reduced up to 22.5% in comparison to the wild-type. No significant reduction in mimosine content was observed in the pydB-expressing lines. This is the first example of using a gene from a bacterial symbiont to reduce the toxicity of a tree-legume.

  17. Biologic fixation of nitrogen in irradiated rhizobium strips; Fixacao biologica do nitrogenio em estirpes de rizobianas irradiadas

    Energy Technology Data Exchange (ETDEWEB)

    Caribe, Rebeka Alves; Colaco, Waldeciro [Pernambuco Univ., Recife, PE (Brazil). Dept. de Energia Nuclear

    2002-07-01

    Native Rhizobium sp. and Bradyrhizobium sp. isolates from the root nodules of bean and cowpea were selected. Six isolates, and the SEMIA 4077 (R. leguminosarum bv. phaseolus) and SEMIA 6145 (Bradyrhizobium sp) strains used as references, were irradiated with ultraviolet light (R-uv) and gamma rays (R-{gamma}). The D{sub 37} values for the rhizobial strain SEMIA 4077 were 43 J.m{sup -2} (UV) and 32 Gy (R-{gamma}) and for the SEMIA 6145 were 45 J.m{sup -2} (UV) and 35 Gy (R-gamma). Through a greenhouse experiment the irradiated isolates were inoculated on bean (P. vulgaris L., cv. Princesa) and on cowpea [Vigna unguiculata, (L.) Walp, cv. IPA-206] seedlings, in an attempt to evaluate the sensitivity of the host plants, and possible effects on their nodulation. Differences in responses to nodulation due to the effect of irradiation were observed for the isolates tested. Significantly differences were observed only for nodules dry matter yield of the IPA-206 cultivar. Gamma irradiated treatment were statistically superior to treatments with ultraviolet light in relation. (author)

  18. 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.

  19. Enhanced Synthesis of Antioxidant Enzymes, Defense Proteins and Leghemoglobin in Rhizobium-Free Cowpea Roots after Challenging with Meloydogine incognita

    Directory of Open Access Journals (Sweden)

    Jose T. A. Oliveira

    2014-11-01

    Full Text Available The root knot nematodes (RKN, Meloydogine spp., particularly Meloidogyne incognita and Meloidogyne javanica species, parasitize several plant species and are responsible for large annual yield losses all over the world. Only a few available chemical nematicides are still authorized for RKN control owing to environmental and health reasons. Thus, plant resistance is currently considered the method of choice for controlling RKN, and research performed on the molecular interactions between plants and nematodes to identify genes of interest is of paramount importance. The present work aimed to identify the differential accumulation of root proteins of a resistant cowpea genotype (CE-31 inoculated with M. incognita (Race 3 in comparison with mock-inoculated control, using 2D electrophoresis assay, mass spectrometry identification and gene expression analyses by RT-PCR. The results showed that at least 22 proteins were differentially represented in response to RKN challenge of cowpea roots mainly within 4–6 days after inoculation. Amongst the up-represented proteins were SOD, APX, PR-1, β-1,3-glucanase, chitinases, cysteine protease, secondary metabolism enzymes, key enzymes involved in ethylene biosynthesis, proteins involved in MAPK pathway signaling and, surprisingly, leghemoglobin in non-rhizobium-bacterized cowpea. These findings show that an important rearrangement in the resistant cowpea root proteome occurred following challenge with M. incognita.

  20. Essential Tremor (ET): Surgical Options

    Science.gov (United States)

    ... t respond to propranolol, primidone, or other common ET medications and whose tremor has become debilitating, there ... treatments were first introduced. Current surgical options for ET include Deep Brain Stimulation (DBS) , Focused Ultrasound Thalamotomy , ...

  1. Et Murstenstårn

    DEFF Research Database (Denmark)

    Jensen, Thomas Bo

    2000-01-01

    Beskrivelse af et kunstnerisk udviklingsarbejde i forbindelse med phd-afhandlingen ”Murstenens ornamentale vilje".......Beskrivelse af et kunstnerisk udviklingsarbejde i forbindelse med phd-afhandlingen ”Murstenens ornamentale vilje"....

  2. Effect of Magnetic Treatment on Amount and Generation Time of Slow-Growing Rhizobium(USDA110) and Fast-growing Rhizobium(USDA191)%磁场处理对根瘤菌(USDA110)和(USDA191)数量及世代时间的影响

    Institute of Scientific and Technical Information of China (English)

    程希雷; 依艳丽

    2009-01-01

    The effects of magnetic treatment on amount and growth rate of slow-growing rhizobium(USDA110)and fast-growing rhizobium(USDA191)by incubation experiments were studied. The results showed that magnetic field had the effects on the growth of rhizobium strains, and all the treatments had positive effects, but magnetic field intensity and treatment time had different effects. The effects of magnetic field intensity and exposure time were different. In magnetic field intensity ,300 mT treatments had the most significant effect. In exposure time, 5 min treatment had the most significant effect and the growth rate of rhizobium was accelerated and generation time was shortened under magnetic treatment after the magnetic treatment.%本试验通过室内培养方法,研究了磁场处理后根瘤菌USDA110(慢生型)和USDA191(快生型)的数量和生长速度的变化.结果表明:磁场对根瘤菌菌落的生长有影响,所有处理均起正效应,但磁场强度和磁处理时间对其影响的效果不同.磁场强度表现为 300 mT效果最显著;磁处理时间以5 min效果最显著.经磁场处理后,根瘤菌的生长速度加快,世代时间缩短.

  3. Charles et ses images

    Directory of Open Access Journals (Sweden)

    Anne-Marie Baron

    2009-01-01

    Full Text Available Charles Bovary est probablement le personnage qui a été le plus transformé par les cinéastes qui ont adapté le roman de Flaubert. Si les premiers adaptateurs l’ont traité en victime, peu à peu, le cinéma a commencé à souligner la dimension néfaste sous-jacente du personnage et à lui faire porter une large part de responsabilité dans la descente aux enfers d’Emma. Depuis Pierre Renoir, touchant et authentique, jusqu’à Gregg Edelman, le mari de Little children qui fantasme sur les photos d’une pin-up virtuelle, en passant par les images plus ou moins pathétiques ou ridicules de Van Heflin, Aribert Wäscher, Alberto Bello, Jean-François Balmer, Farooq Shaikh ou Luis-Miguel Cintra, Charles, plus que tout autre personnage du roman, a subi une incroyable métamorphose en s’ancrant dans la civilisation de chacun des pays et de chacune des décennies successives qui l’ont porté à l’écran.From the 1930s to the present, Charles Bovary is probably the most altered character in the adaptations of Flaubert’s novel. The first directors made a victim of him, but gradually, the cinema began to emphasize his deleterious dimension and attributed to him a large part of the responsibility for Emma’s grief. From Pierre Renoir, touching and authentic, to Gregg Edelman, who fantasizes on a pornographic website in Todd Field’s Little Children, the more or less pathetic or ridiculous portrayals given by Van Heflin, Aribert Wäscher,Alberto Bello, Jean-François Balmer, Farooq Shaikh or Luis-Miguel Cintra, show that more than any other character in the novel, Charles has been submitted to a serious metamorphosis by being interpreted on screen according to each country’s civilization and the successive decades of filming.

  4. 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.

  5. Diversity of Plasmid Profiles and Conservation of Symbiotic Nitrogen Fixation Genes in Newly Isolated Rhizobium Strains Nodulating Sulla (Hedysarum coronarium L.).

    Science.gov (United States)

    Mozo, T; Cabrera, E; Ruiz-Argüeso, T

    1988-05-01

    Forty-five Rhizobium strains nodulating sulla (Hedysarum coronarium L.), isolated from plants grown in different sites in Menorca Island and southern Spain, were examined for plasmid content and the location and organization of nif (nitrogen fixation) and nod (nodulation) sequences. A great diversity in both number and size of the plasmids was observed in this native population of strains, which could be distributed among 19 different groups according to their plasmid profiles. No correlation was found between plasmid profile and geographical origin of the strains. In each strain a single plasmid ranging from 187 to 349 megadaltons hybridized to Rhizobium meliloti nifHD and nodD DNA, and in three strains the spontaneous loss of this plasmid resulted in the loss of the nodulation capacity. In addition to the symbiotic plasmid, 18 different cryptic plasmids were identified. A characteristic cryptic plasmid of >1,000 megadaltons was present in all strains. Total DNA hybridization experiments, with nifHD and portions of nodC and nodD genes (coding for common nodulation functions) from R. meliloti as probes, demonstrated that both the sequence and organization of nif and common nod genes were highly conserved within rhizobia nodulating sulla. Evidence for reiteration of nodD sequences and for linkage of nodC to at least one copy of nodD was obtained for all the strains examined. From these results we conclude that Rhizobium strains nodulating sulla are a homogeneous group of symbiotic bacteria that are closely related to the classical fast-growing group of rhizobia.

  6. Optimisation combinatoire Theorie et algorithmes

    CERN Document Server

    Korte, Bernhard; Fonlupt, Jean

    2010-01-01

    Ce livre est la traduction fran aise de la quatri me et derni re dition de Combinatorial Optimization: Theory and Algorithms crit par deux minents sp cialistes du domaine: Bernhard Korte et Jens Vygen de l'universit de Bonn en Allemagne. Il met l accent sur les aspects th oriques de l'optimisation combinatoire ainsi que sur les algorithmes efficaces et exacts de r solution de probl mes. Il se distingue en cela des approches heuristiques plus simples et souvent d crites par ailleurs. L ouvrage contient de nombreuses d monstrations, concises et l gantes, de r sultats difficiles. Destin aux tudia

  7. Lupus et Çrossesse

    OpenAIRE

    benyetou, faiza

    2012-01-01

    - La grossesse est une période particulièrement importante pour une femme atteinte de lupus. ii existe un risque maternel et foetal mais une prise en charge spécialisée et bien coordonnée permet de réduire ces risques, cette période a également une dimension psychologique et affective majeure dont il faut tenir compte et s'astreindre à préparer médicalement et humainement. - Le pronostic maternel de la grossesse est actuellement bon sous réserve d'une surveillance programmée...

  8. Genre, raison et nation

    Directory of Open Access Journals (Sweden)

    Rada Ivekovic

    2009-01-01

    Full Text Available Ce travail s’intéresse aux mécanismes de sexuation et de subjectivation dans la construction de la nation. Quelques-uns ont postulé le “retard” de certains groupes sociaux par rapport à l’avènement de la “modernité”, concernant notamment les sujets extraeuropéens, mais aussi les femmes. En réalité, il n’y a pas de retard soit des femmes, soit des peuples colonisés en matière de modernité, parce que la norme de celle-ci est établie elle-même de façon arbitraire à partir d’une position de domination hégémonique depuis la modernité occidentale.

  9. Poliovirus et Apoptose

    OpenAIRE

    2007-01-01

    Le poliovirus est l'agent responsable de la poliomyélite paralytique aigüe. Les paralysies flasques caractéristiques de la poliomyélite résultent de la destruction des neurones moteurs, les cellules cibles spécifiques du poliovirus dans le système nerveux central (SNC). Le développement de nouveaux modèles animaux et cellulaires a permis d'étudier les étapes clés de la pathogénèse de la poliomyélite à un niveau moléculaire. En particulier il a été montré chez la souris que l'induction de l'ap...

  10. Fait migratoire et genre

    OpenAIRE

    Zaidman, Claude

    2009-01-01

    « Issus de l’immigration », « d’origine étrangère », « Deuxième génération »... Les catégories construites pour désigner les enfants de parents migrants sont diverses. Elles évoluent dans le temps, en fonction de l’histoire de l’immigration et des politiques de l’immigration ; en outre, elles varient selon la place dans l’institution des divers locuteurs : chercheurs, administrateurs, enseignants, élèves eux-mêmes. Dans le même numéro d’une revue parue en 1980, trois titres d’articles utilis...

  11. Hyalinosis cutis et mucosae.

    Science.gov (United States)

    Vago, Bernadette; Hausser, Ingrid; Hennies, Hans Christian; Enk, Alexander; Jappe, Uta

    2007-05-01

    Hyalinosis cutis et mucosae is a rare autosomal recessive disorder which is characterized by deposition of hyaline material around the basement membrane of the skin and mucous membranes. Typical clinical symptoms are hoarseness, infiltration of the mucous membranes and papular verrucous skin changes. Mutations within the extracellular matrix protein gene (ECM-1) are the underlying defect. We report on a 24-year-old man, who had first been seen in our department at the age of seven and had undergone the necessary diagnostic procedures and who revisited 17 years later with hoarseness and extensive verrucous skin changes at elbows and knees which were removed by excision. A new mutation of the ECM1 gene was identified.

  12. Fiction et typification.

    Directory of Open Access Journals (Sweden)

    Nathalie Zaccaï-Reyners

    2005-04-01

    Full Text Available Par quelles voies les acquis cognitifs de l’expérience sont-ils mobilisés par ego dans la suite de ses actions, et sont-ils transmis à autrui ? Contrairement à la phénoménologie sociale d’Alfred Schütz dans le cadre de laquelle ces questions sont renvoyées à des processus de généralisation et de stabilisation pensés sous le prisme de la typification sociale, la théorie des fictions élaborée par Jean-Marie Schaeffer appréhende la modélisation de l’expérience vécue à partir des spécificités d’une forme proprement ludique d’expérience. Les blocages décrits par Schütz lorsqu’il envisage les situations exemplaires de l’étranger ou du soldat revenant du front y trouvent un nouvel éclairage. Proposition de mots clés :How are cognitive elements of experience available for the continuation of ego’s action, and how are they passed on to alter ? In the social phenomenology of Alfred Schutz for instance, these questions are related back to generalisation and stabilisation processes viewed through the light of social typification. On the other hand, Jean-Marie Schaeffer’s theory of fiction comprehends the modelling of some lived experiences as the fact of a specific form of ludic experience. It provides a new light on the obstructions described by Schutz considering the exemplar situations of the stranger or of the homecomer.

  13. 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.

  14. Interacción simbiótica Rhizobium-leguminosas arbóreas en sistemas contaminados con hidrocarburos policíclicos aromáticos.

    OpenAIRE

    López Ortiz, Carlos

    2011-01-01

    En este estudio se evaluó el establecimiento de la simbiosis entre Rhizobium tropici CIAT899 y las leguminosas arbóreas Leucaena leucocephala (Lam.) y Acaciella angustissima (Mill.) en sistemas contaminados con naftaleno (NAF) y fenantreno (FEN), y contempló dos fases experimentales. En la primera fase se evaluó el efecto de NAF y FEN en la dinámica de formación de nódulos, así como la respuesta de la planta en el contenido de compuestos fenólicos totales, actividad antioxidante total y conte...

  15. Symbiotic nitrogen fixation by a nifA deletion mutant of Rhizobium meliloti: the role of an unusual ntrC allele.

    OpenAIRE

    Labes, M; RASTOGI, V; Watson, R.; Finan, T M

    1993-01-01

    In the N2-fixing alfalfa symbiont Rhizobium meliloti, the three sigma 54 (NTRA)-dependent positively acting regulatory proteins NIFA, NTRC, and DCTD are required for activation of promoters involved in N2 fixation (pnifHDKE and pfixABCX), nitrogen assimilation (pglnII), and C4-dicarboxylate transport (pdctA), respectively. Here, we describe an allele of ntrC which results in the constitutive activation of the above NTRC-, NIFA-, and DCTD-regulated promoters. The expression and activation of w...

  16. 苯磺隆对花生根瘤菌生长的影响%Influence of Tribenuron-methyl on the Growth of Peanut Rhizobium

    Institute of Scientific and Technical Information of China (English)

    叶龙; 刘世旺; 徐艳霞; 黄小颖; 颜蕾

    2012-01-01

    [Objective] To study the influence of tribenuron-methyl (TM) on the growth curve of peanut rhizobium. [Method] The growth of rhizombium on six culture media, including YMA, YMA + TM, 0.5 YMA +TM, no N source, no C source, no N and no C sources, was observed , and their growth curves on the six media were drawn. [ Result] The growth of peanut rhizobium was slightly suppressed in YMA -f TM 200 mg/L medium. Tn the medium without N source, peanut rhizobia could utilize txibenuron-methyl to survive. [Conclusion] The effect of trihenuron-methyl on the growth of peanut rhizobium was small when the nutrient was rich and the tribenuron-methyl could even be degraded and used by peanut rhizobium- The research provided theoretical basis for improving the nitrogen fixation activities and peanut yield.%[目的]探讨苯磺隆(TM)对花生根瘤菌生长的影响规律.[方法]观察根瘤菌在YMA、YMA+ TM、0.5YMA+ TM、缺N源、缺C源、缺N缺C(双缺)培养基上的菌落生长情况,并分别绘制6种培养基对应的根瘤菌生长曲线.[结果]在YMA+ TM 200 mg/L培养基中,TM对花生根瘤菌生长仅有轻微抑制作用;在没有N源时,花生根瘤菌能利用TM而生存.[结论]在营养丰富时,TM对花生根瘤菌生长的影响较小,TM还可被花生根瘤菌降解利用.该研究为提高根瘤菌固氮活力并进一步提高花生产量提供了理论依据.

  17. Molekularbiologische und genetische Untersuchungen zur Regulation des zentralen Regulators der Stickstofffixierung NifA in Rhizobium leguminosarum bv. viciae VF39

    OpenAIRE

    Saeglitz, Nico

    2008-01-01

    Expression of nif and fix genes in rhizobia is strictly regulated. The dominating regulator within the regulation of nif and fix gene expression is NifA. This work presents, that two promotors are involved in nifA gene expression in Rhizobium leguminosarum bv. viciae VF39, namely P1, located at the downstream end of fixX and PfixA, the promotor of the fixA gene, located 3600bp upstream of P1. P2, a promotor identified by transcriptional mapping was shown to be pointless in earlier works and c...

  18. Symbiotic nitrogen fixation by a nifA deletion mutant of Rhizobium meliloti: the role of an unusual ntrC allele.

    OpenAIRE

    Labes, M; Rastogi, V; Watson, R.; Finan, T M

    1993-01-01

    In the N2-fixing alfalfa symbiont Rhizobium meliloti, the three sigma 54 (NTRA)-dependent positively acting regulatory proteins NIFA, NTRC, and DCTD are required for activation of promoters involved in N2 fixation (pnifHDKE and pfixABCX), nitrogen assimilation (pglnII), and C4-dicarboxylate transport (pdctA), respectively. Here, we describe an allele of ntrC which results in the constitutive activation of the above NTRC-, NIFA-, and DCTD-regulated promoters. The expression and activation of w...

  19. Study on rheological property and toxicity of exopolysaccharide from Rhizobium sp.N613%Rhizobium sp.N613胞外多糖流变性及毒性研究

    Institute of Scientific and Technical Information of China (English)

    任盛; 程红兵; 陈艳丽; 谢红; 赵良启

    2009-01-01

    主要研究了浓度、剪切力、温度、pH、盐离子浓度、加热时间、冻融变化、微波及超声波处理等对Rhizobium sp.N613(REPS)胞外多糖粘度的影响.实验结果表明:REPS溶液的粘度随着浓度的增加而增加,当浓度达到0.9%时,其粘度为41.5mPa·s;REPS溶液为非牛顿流体.具有假塑性;REPS的最佳溶解温度为70℃,加热时间以1.5h为宜;pH、冻融变化、短时间微波和超声波处理时REPS溶液的粘度影响较小;REPS有良好的耐盐稳定性和抗降解性能;0.6%REPS溶液的吸光度为0.758,透光率为17.78%.在水中的溶解度为31.67%.此外,还进行了REPS的特性粘度、急性毒性测试和蓄积毒性实验,结果表明,该多糖具有粘度高、无毒性的特点,在食品加工等领域有着广泛的应用前景.

  20. 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