Sample records for rhizobium etli final

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

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    Handelsman, Jo


    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.

  2. The naringenin-induced exoproteome of Rhizobium etli CE3. (United States)

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


    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.

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


    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


    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...

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

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    González Víctor


    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.

  5. Transcriptomic analysis of the process of biofilm formation in Rhizobium etli CFN42. (United States)

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


    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.

  6. The relaxase of the Rhizobium etli symbiotic plasmid shows nic site cis-acting preference. (United States)

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


    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.

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

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    Mendoza-Hernández Guillermo


    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.

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

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    Beullens Serge


    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)


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


    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. (United States)

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


    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. BacS: an abundant bacteroid protein in Rhizobium etli whose expression ex planta requires nifA. (United States)

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


    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.

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

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


    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

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


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


    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...

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


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


    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...

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

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


    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.

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

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    Juárez-Cisneros Gladys


    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.

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

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


    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.

  18. 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. (United States)

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


    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.

  19. The symbiovar trifolii of Rhizobium bangladeshense and Rhizobium aegyptiacum sp. nov. nodulate Trifolium alexandrinum in Egypt. (United States)

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


    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)).

  20. Evolution of rhizobium symbiosis

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    Camp, Op den R.H.M.


    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

  1. 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

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    张武; 马金田; 潘伟; 雷腾英


    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.

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

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    Lachaâl M.


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

  3. 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. (United States)

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


    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.

  4. 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. (United States)

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


    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.

  5. Identification of the σ⁷⁰-Dependent Promoter Controlling Expression of the ansPAB Operon of the Nitrogen-Fixing Bacterium Rhizobium etli. (United States)

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


    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.

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


    Breedveld, M W


    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...

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

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


    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.

  8. Rhizobium pusense is the main human pathogen in the genus Agrobacterium/Rhizobium. (United States)

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


    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.

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

    NARCIS (Netherlands)

    Breedveld, M.W.


    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

  10. Denitrification by Rhizobium meliloti

    Energy Technology Data Exchange (ETDEWEB)

    Rosen, A.


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

  11. The celC gene, a new phylogenetic marker useful for taxonomic studies in Rhizobium. (United States)

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


    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.

  12. 78 FR 33437 - United States v. Apple, Inc., et al.; Public Comments and Response on Proposed Final Judgment (United States)


    ... Antitrust Division United States v. Apple, Inc., et al.; Public Comments and Response on Proposed Final... Macmillan in United States v. Apple, Inc., et al., Civil Action No. 12-CV-2826 (DLC), which was filed in the... for the Southern District of New York UNITED STATES OF AMERICA, Plaintiff, v. APPLE, INC., et...

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

    CERN Document Server

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


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

  14. 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

    Directory of Open Access Journals (Sweden)

    F. M. Mercante


    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.

  15. Rhizobium metallidurans sp. nov., a symbiotic heavy metal resistant bacterium isolated from the Anthyllis vulneraria Zn-hyperaccumulator. (United States)

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


    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

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

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


    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)).

  17. 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


    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.

  18. 75 FR 29647 - Tart Cherries Grown in the States of Michigan, et al.; Final Free and Restricted Percentages for... (United States)


    ... Service 7 CFR Part 930 Tart Cherries Grown in the States of Michigan, et al.; Final Free and Restricted... Federal marketing order regulating tart cherries grown in seven States (order). The percentages are 32... tart cherries grown in the States of Michigan, New York, Pennsylvania, Oregon, Utah, Washington,...

  19. 77 FR 36115 - Tart Cherries Grown in the States of Michigan, et al.; Final Free and Restricted Percentages for... (United States)


    ... Service 7 CFR Part 930 Tart Cherries Grown in the States of Michigan, et al.; Final Free and Restricted Percentages for the 2011-12 Crop Year for Tart Cherries AGENCY: Agricultural Marketing Service, USDA. ACTION... year under the marketing order for tart cherries grown in the states of Michigan, New...

  20. 75 FR 12702 - Tart Cherries Grown in the States of Michigan, et al.; Final Free and Restricted Percentages for... (United States)


    ...; ] DEPARTMENT OF AGRICULTURE Agricultural Marketing Service 7 CFR Part 930 Tart Cherries Grown in the States of Michigan, et al.; Final Free and Restricted Percentages for the 2009-2010 Crop Year for Tart Cherries... order regulates the handling of tart cherries grown in the States of Michigan, New York,...

  1. 76 FR 10471 - Tart Cherries Grown in the States of Michigan, et al.; Final Free and Restricted Percentages for... (United States)


    ... Marketing Service 7 CFR Part 930 Tart Cherries Grown in the States of Michigan, et al.; Final Free and Restricted Percentages for the 2010-2011 Crop Year for Tart Cherries AGENCY: Agricultural Marketing Service... the tart cherry marketing order for the 2010-2011 crop year. The percentages are 58 percent free...

  2. 77 FR 12748 - Tart Cherries Grown in the States of Michigan, et al.; Final Free and Restricted Percentages for... (United States)


    ...; ] DEPARTMENT OF AGRICULTURE Agricultural Marketing Service 7 CFR Part 930 Tart Cherries Grown in the States of Michigan, et al.; Final Free and Restricted Percentages for the 2011-12 Crop Year for Tart Cherries AGENCY... tart cherries grown in the states of Michigan, New York, Pennsylvania, Oregon, Utah, Washington,...

  3. Evolutionary origin of rhizobium Nod factor signaling

    NARCIS (Netherlands)

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


    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

  4. D'une ouverture de la voyelle /epsilon/ en finale absolue en francais quebecois : analyse acoustique et perceptive (United States)

    Riverin-Coutlee, Josiane

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

  5. Transposon Tn5 specifies streptomycin resistance in Rhizobium spp.



    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...

  6. Immunosuppression during Rhizobium-legume symbiosis. (United States)

    Luo, Li; Lu, Dawei


    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.

  7. Evolutionary origin of rhizobium Nod factor signaling. (United States)

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


    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.

  8. Rhizobium yantingense sp. nov., a mineral-weathering bacterium. (United States)

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


    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 name yantingense sp. nov. is proposed for this novel species. The type strain is H66(T) ( = CCTCC AB 2014007(T) = LMG 28229(T)).

  9. Rhizobium halotolerans sp. nov., Isolated from chloroethylenes contaminated soil. (United States)

    Diange, Eboa Adolf; Lee, Sang-Seob


    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)).

  10. Nodulation of Acacia Species by Fast- and Slow-Growing Tropical Strains of Rhizobium


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


    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.

  11. (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.


    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.

  12. Rhizobium calliandrae sp. nov., Rhizobium mayense sp. nov. and Rhizobium jaguaris sp. nov., rhizobial species nodulating the medicinal legume Calliandra grandiflora. (United States)

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


    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)).

  13. Widespread fitness alignment in the legume-rhizobium symbiosis. (United States)

    Friesen, Maren L


    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.

  14. Optimization of dairy sludge for growth of Rhizobium cells. (United States)

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


    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.

  15. Rhizobium herbae sp. nov. and Rhizobium giardinii-related bacteria, minor microsymbionts of various wild legumes in China. (United States)

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


    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.

  16. TOLERANCIA A ACIDEZ EN Rhizobium trifolii


    Bueno Castillo, Carmen


    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...

  17. Phylogenetic diversity of Rhizobium strains nodulating diverse legume species growing in Ethiopia. (United States)

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


    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.

  18. Rhizobium helianthi sp. nov., isolated from the rhizosphere of sunflower. (United States)

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


    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).

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

    Directory of Open Access Journals (Sweden)

    Lin, XG.


    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.

  20. Analysis of synonymous codon usage patterns in the genus Rhizobium. (United States)

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


    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.

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  2. Production of nodulation factors by Rhizobium meliloti: fermentation, purification and characterization of glycolipids. (United States)

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


    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.


    Directory of Open Access Journals (Sweden)



    Full Text Available Le calibre de plantation est un paramètre qui conditionne d’une manière importante la production et la dimension des tubercules-fils de la pomme de terre. A travers notre étude menée sur deux années (1991/92 et 1993/94, nous avons cherché à mettre en relief l’effet du calibre de plantation sur le rendement et la répartition de la production par classe des tubercules selon leur diamètre. Dans ce contexte, nous avons combiné les effets du calibre de plantation à trois niveaux (45/55, 35/45 et 28/35 chez quatre variétés (Desirée, Diamant, Nicola et Chieftain, dans les conditions agro-climatiques de la région de Sétif. Les résultats obtenus montrent que le calibre de plantation a un effet favorable sur le rendement final et sur le répartition des tubercules- fils. Le calibre (28/35 a tendance à produire des gros tubercules (> 55 mm, fraction destinée à la consommation. Par contre, les calibres (45/55 et (35/45 ont tendance à produire des moyens et petits tubercules (< 45 mm; cette fraction est destinée, d’une manière générale, à la semence, à l’exception des petits tubercules inférieurs à 28 mm, qui sont appréciés également à la consommation. De ce fait, le calibre de plantation pourrait être un moyen de contrôle de rendement et de la qualité physique des tubercules-fils, à savoir sa grosseur.

  4. Physiological role of calcium in legume-rhizobium symbiosis

    Directory of Open Access Journals (Sweden)

    Vasil’eva G.G.


    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.

  5. Rhizobium petrolearium sp. nov., isolated from oil-contaminated soil. (United States)

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


    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.


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


    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.

  7. Rhizobium-legume symbioses: the crucial role of plant immunity. (United States)

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


    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.

  8. 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. (United States)

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


    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 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.

  9. Common links in the structure and cellular localization of Rhizobium chitolipooligosaccharides and general Rhizobium membrane phospholipid and glycolipid components. (United States)

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


    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.

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


    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.

  11. Organic Acid Metabolism by Isolated Rhizobium japonicum Bacteroids (United States)

    Stovall, Iris; Cole, Michael


    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

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

    NARCIS (Netherlands)

    Frings, J.F.J.


    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

  13. A novel capsular polysaccharide from Rhizobium rubi strain DSM 30149. (United States)

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


    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.

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

    NARCIS (Netherlands)

    Sessitsch, A.


    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

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

    NARCIS (Netherlands)

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


    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

  16. Diversity of Rhizobium leguminosarum from pea fields in Washington State (United States)

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

  17. A rhizobium selenitireducens protein showing selenite reductase activity (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...

  18. Rhizobium laguerreae sp. nov. nodulates Vicia faba on several continents. (United States)

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


    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)).

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

    NARCIS (Netherlands)

    Krogt, van der G.N.M.


    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

  20. Final Report: Research Study on Development of Environmental Friendly Spray-on Foam Insulation (SOFI) for the External Tank (ET) (United States)

    Stuckey, James M.


    The selection and quantification of four foams using a more environmentally friendly HCFC-141b blowing agent replacing foams that used the CFC-11 blowing agent for the external tank (ET) LWT has been addressed along with problems and solutions that were encountered during verification. The effort on two lower density spray foams for the ET SLWT are presented, but predicted weight savings were not encouraging. Suggestions for possible problem solving are included along with a new approach for selecting foams for qualification as back-up foams for the foams used on the ET LWT. We investigated three resins for use as thermally sprayed coatings for corrosion prevention on metal. The best coating was obtained with a thermoplastic polyimide resin. This coating has a good chance of meeting ET requirements. Possible third generation blowing agents have been shown usable in polyurethane spray and pour foams, and solubility in isocyannate foam components are acceptable. We considered aerogels as insulation materials on space vehicles, and suggested a liner for a liquid oxygen (LOX) composite tank.

  1. Rhizobium lemnae sp. nov., a bacterial endophyte of Lemna aequinoctialis. (United States)

    Kittiwongwattana, Chokchai; Thawai, Chitti


    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)).

  2. Rhizobium paknamense sp. nov., isolated from lesser duckweeds (Lemna aequinoctialis). (United States)

    Kittiwongwattana, Chokchai; Thawai, Chitti


    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)).

  3. Rhizobium pseudoryzae sp. nov., isolated from the rhizosphere of rice. (United States)

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


    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)).

  4. Rhizobium rhizoryzae sp. nov., isolated from rice roots. (United States)

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


    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)).

  5. Rhizobium alvei sp. nov., isolated from a freshwater river. (United States)

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


    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)).

  6. Genetic diversity of Rhizobium from nodulating beans grown in a variety of Mediterranean climate soils of Chile. (United States)

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


    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 %.

  7. [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.


    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.

  8. Impact of heavy metals on an arctic rhizobium

    Energy Technology Data Exchange (ETDEWEB)

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


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

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


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


    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....

  10. Rhizobium pongamiae sp. nov. from root nodules of Pongamia pinnata. (United States)

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


    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.

  11. Rhizobium rosettiformans sp. nov., isolated from a hexachlorocyclohexane dump site, and reclassification of Blastobacter aggregatus Hirsch and Muller 1986 as Rhizobium aggregatum comb. nov. (United States)

    Kaur, Jaspreet; Verma, Mansi; Lal, Rup


    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

  12. Root Exudates of Various Host Plants of Rhizobium leguminosarum Contain Different Sets of Inducers of Rhizobium Nodulation Genes. (United States)

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


    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.

  13. Rhizobium ipomoeae sp. nov., isolated from a water convolvulus field. (United States)

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


    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).

  14. Effects of nano-ZnO on the agronomically relevant Rhizobium-legume symbiosis (United States)

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

  15. 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.


    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. 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.


    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

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


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


    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.

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

    NARCIS (Netherlands)

    Schetgens, T.M.P.


    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

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

    NARCIS (Netherlands)

    Krol, A.J.M.


    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

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

    NARCIS (Netherlands)

    Seifi Kalhor, M.


    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.

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

    DEFF Research Database (Denmark)

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


    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....

  2. Effects of nano-TiO2 on the agronomically-relevant Rhizobium-legume symbiosis (United States)

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

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

    NARCIS (Netherlands)

    Laane, N.C.M.


    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

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

    Directory of Open Access Journals (Sweden)

    Stéphane Legrand


    Full Text Available Cet article traite du concept de « dégénérescence », importé dans la psychiatrie française par Benedict-Auguste Morel dans les années 1850, et largement diffusé par la suite, dans ce champ ainsi que dans celui de la criminologie. On tente d’analyser la reconfiguration qu’impose ce concept au savoir psychiatrique en dégageant la manière dont il permet d’intégrer en un ensemble cohérent plusieurs modèles théoriques: un paradigme neurologique, une théorie de l’automatisme morbide, un certain évolutionnisme. Sur ces bases, on essaie d’établir les similitudes de fonds existant entre les conceptions psychiatrique et criminologique de la dégénérescence, en montrant qu’elles mobilisent le même réseau « structurant » d’analogies entre les figures de l’anormal (le fou, le sauvage, l’enfant, la femme, l’animal; et l’on s’efforce de montrer que ces théories promeuvent une logique dans laquelle les infractions aux différents types de normes (biologiques, sociales, morales, juridiques, psychologiques, économiques sont susceptibles de faire systématiquement référence les unes aux autres, de se traduire les unes dans les autres. Puis l’on caractérise les transformations que ce nouveau paradigme impose aux principes de la thérapeutique, de la pédagogie et de la prise en charge des malades mentaux et des déviants. Pour finir, on présente les éléments latents qui dans ce paradigme préparent et indiquent déjà sa remise en cause et son renversement à venir.This article deals with the concept of «degeneration», introduced by Benedict-Auguste Morel in the French psychiatry during the 1850s, and which widely spread afterwards, in this field as well as in the contemporary criminology. An analysis is tried of the changes imposed by this notion on the psychiatric knowledge, changes that resulted in the integration in a coherent system of three other paradigms: a neurological paradigm, a theory of

  5. Viability of Rhizobium bacteroids isolated from soybean nodule protoplasts. (United States)

    Gresshoff, P M; Rolfe, B G


    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.

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

    DEFF Research Database (Denmark)

    Engvild, Kjeld Christensen; Nielsen, G.


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

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

    Institute of Scientific and Technical Information of China (English)


    [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.

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

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


    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)).


    Directory of Open Access Journals (Sweden)

    Ni Made Widyasari


    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.

  10. L’espace domestique au Bronze final et au premier âge du Fer dans le sud de la Corse

    Directory of Open Access Journals (Sweden)

    Peche-Quilichini, Kewin


    organización general como a nivel del espacio interno y de la arquitectura de las viviendas. [fr] L’objectif de cet article est de fournir une approche synthétique sur les formes de l’habitat en Corse au Bronze final (BF et au premier âge du Fer (F1, à l’échelle de la microrégion montagneuse de l’Alta Rocca, située dans le sud de la Corse, au coeur du bassin occidental de la Méditerranée. La problématique d’étude des sites protohistoriques non fortifiés est jeune sur l’île, mais les travaux se sont récemment multipliés et rendent compte de la complexité structurelle et évolutive des espaces habités, permettant ainsi une premiére analyse comparative. Le raisonnement s’appuie essentiellement sur l’apport des fouilles du grand habitat de Cuciurpula, initiées en 2008 et toujours en cours, ainsi que sur l’exploitation des villages de Puzzonu et de Nuciaresa, sondés en 2012. La chronologie des secteurs étudiés permet d’embrasser un arc chronologique complet entre le XIIe et le VIe siécle av. J.-C., et donc d’appréhender les phénoménes évolutifs, tant en termes d’organisation générale qu’au niveau de l’espace interne et de l’architecture des habitations.

  11. Microgravity effects on the legume/Rhizobium symbiosis (United States)

    Urban, James E.


    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.

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


    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.

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


    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

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

    Directory of Open Access Journals (Sweden)

    Diego Rivera


    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.

  15. 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.


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

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


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


    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 ...

  17. Permanent draft genome of the malachite-green-tolerant bacterium Rhizobium sp. MGL06. (United States)

    Liu, Yang; Wang, Runping; Zeng, Runying


    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.

  18. Genome sequence of the acid-tolerant strain Rhizobium sp. LPU83. (United States)

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


    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.

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

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


    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)).

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

    Directory of Open Access Journals (Sweden)

    Eny Fuskhah


    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. Rhizobium vallis sp. nov., isolated from nodules of three leguminous species. (United States)

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


    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.

  2. Rhizobium vignae sp. nov., a symbiotic bacterium isolated from multiple legume species. (United States)

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


    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)).

  3. Rhizobium tubonense sp. nov., isolated from root nodules of Oxytropis glabra. (United States)

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


    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.

  4. High lipid productivity of an Ankistrodesmus-Rhizobium artificial consortium. (United States)

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


    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.

  5. 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

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


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


    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...

  7. Rhizobium halophytocola sp. nov., isolated from the root of a coastal dune plant. (United States)

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


    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

  8. 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


    Harahap, Irwan Pandapotan


    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...

  9. Rhizobium taibaishanense sp. nov., isolated from a root nodule of Kummerowia striata. (United States)

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


    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.

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

    Directory of Open Access Journals (Sweden)

    Rina Kurniaty


    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.

  11. 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. (United States)

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


    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)).

  12. Rhizobium tarimense sp. nov., isolated from soil in the ancient Khiyik River. (United States)

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


    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)).

  13. Mapping the genetic basis of symbiotic variation in legume-rhizobium interactions in Medicago truncatula. (United States)

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


    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.

  14. Rhizobium oryzicola sp. nov., potential plant-growth-promoting endophytic bacteria isolated from rice roots. (United States)

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


    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)).

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

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


    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

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

    DEFF Research Database (Denmark)

    Skøt, Leif


    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....

  17. [Construction of Frankia genomic libraries and isolation of clones homologous to nodulation genes from Rhizobium leguminosarum]. (United States)

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


    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. Herbivores alter the fitness benefits of a plant-rhizobium mutualism (United States)

    Heath, Katy D.; Lau, Jennifer A.


    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.

  19. [The Effect of Cadmium on the Efficiency of Development of Legume-Rhizobium Symbiosis]. (United States)

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


    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.

  20. Strain identification and quorum sensing inhibition characterization of marine-derived Rhizobium sp. NAO1 (United States)

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


    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.

  1. Rhizobium skierniewicense sp. nov., isolated from tumours on chrysanthemum and cherry plum. (United States)

    Puławska, Joanna; Willems, Anne; Sobiczewski, Piotr


    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).

  2. Rhizobium nepotum sp. nov. isolated from tumors on different plant species. (United States)

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


    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.

  3. Rhizobium azibense sp. nov., a nitrogen fixing bacterium isolated from root-nodules of Phaseolus vulgaris. (United States)

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


    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.

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

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


    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)).

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


    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. 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)


    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

  7. Genetic regulation of nitrogen fixation in Rhizobium meliloti. (United States)

    Cebolla, A; Palomares, A J


    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.

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


    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)).

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


    Mendes, Ieda C.; Bottomley, Peter J.


    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 (

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

    NARCIS (Netherlands)

    Roelvink, P.W.


    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

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

    NARCIS (Netherlands)

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


    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

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

    NARCIS (Netherlands)

    Klein Lankhorst, R.


    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

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

  14. Genome Sequence of the Symbiotic Type Strain Rhizobium tibeticum CCBAU85039T (United States)

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


    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

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

    DEFF Research Database (Denmark)

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


    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...

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

    DEFF Research Database (Denmark)

    Rosendahl, Lis


    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...

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


    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)).

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


    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).

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


    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.

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

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

    NARCIS (Netherlands)

    Heidstra, R.


    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

  2. 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.


    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

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

    NARCIS (Netherlands)

    Appels, M.A.


    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

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

    NARCIS (Netherlands)

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


    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

  5. Rhizobium populi sp. nov., an endophytic bacterium isolated from Populus euphratica. (United States)

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


    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

  6. Rhizobium marinum sp. nov., a malachite-green-tolerant bacterium isolated from seawater. (United States)

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


    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).

  7. The nodC, nodG, and glgX genes of Rhizobium tropici strain PRF 81. (United States)

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


    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.

  8. 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


    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

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


    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)).

  10. Rhizobium subbaraonis sp. nov., an endolithic bacterium isolated from beach sand. (United States)

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


    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)).

  11. Rhizobium smilacinae sp. nov., an endophytic bacterium isolated from the leaf of Smilacina japonica. (United States)

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


    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)).

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

    Directory of Open Access Journals (Sweden)

    Ladan Bayat


    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Lamy, C.


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

  14. Rhizobium phenanthrenilyticum sp. nov., a novel phenanthrene-degrading bacterium isolated from a petroleum residue treatment system. (United States)

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


    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.

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

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    Antonio Roberto Giardini


    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

  16. La plaquette à chevaux hypertrophiques de Lumentxa (Biscaye et les styles du Magdalénien supérieur/final dans le Pays Basque.

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    Juan Mª Apellaniz


    Full Text Available Se ofrece un análisis de la plaqueta de hematites de la cueva de Lumentxa, fechada tradicionalmente en el Magdaleniense superior/final, desde el punto de vista formal y macroscópico. El examen del trazo y del desplazamiento o de la mano de las figuras del anverso, así como la identidad de estilo y forma, lleva al autor a sugerir la hipótesis de la misma autoría para las dos figuras, así como las diferencias de trazo y mano, así como la tendencia a la exageración de los caracteres estilísticos le conduce a suponer que el prótomo del reverso es atribuible a otro autor. El análisis formal permite atribuir esta obra a una corriente de carácter expresionista que se entrecruza con el estilo esquemático, uno de los más comunes del Magdaleniense superior/final. El autor, que ha sugerido la hipótesis del origen de la tendencia expresionista en la escuela de grabadores de La Madeleine (Tursac en otro trabajo, pone la plaqueta de Lumentxa en relación con aquella corriente y en concreto con un segundo momento del esquematismo expresionista que observa en ella. Considera la obra como un eco a punto de extinguirse de la corriente expresionista, de la que en el Cantábrico no quedan muchos recuerdos.

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

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    Paula García-Fraile

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

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


    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.

  19. 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)


    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)

  20. Rhizobium strains differ considerably in outer membrane permeability and polymyxin B resistance. (United States)

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


    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.

  1. Selection for cheating across disparate environments in the legume-rhizobium mutualism. (United States)

    Porter, Stephanie S; Simms, Ellen L


    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.

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

    Energy Technology Data Exchange (ETDEWEB)

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


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

  3. Transmissible Resistance to Penicillin G, Neomycin, and Chloramphenicol in Rhizobium japonicum1 (United States)

    Cole, Michael A.; Elkan, Gerald H.


    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

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


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


    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...

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


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


    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...

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


    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)).

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

    Sánchez-Cañizares, Carmen; Palacios, Jose


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

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


    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.


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    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.

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

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    Smadar Peleg-Grossman

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

  11. Rhizobium anhuiense as the predominant microsymbionts of Lathyrus maritimus along the Shandong Peninsula seashore line. (United States)

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


    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.

  12. Effects of nano-ZnO on the agronomically relevant Rhizobium-legume symbiosis. (United States)

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


    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.

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

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    Erneste HAVUGIMANA


    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.

  14. Rhizobium flavum sp. nov., a triazophos-degrading bacterium isolated from soil under the long-term application of triazophos. (United States)

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


    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)).

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

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    Antonio Roberto Giardini


    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.

  16. 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


    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

  17. Synergism of VAM and Rhizobium on production and metabolism of IAA in roots and root nodules of Vigna mungo. (United States)

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


    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.

  18. 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. (United States)

    Mehry, Askary; Akbar, Mostajeran; Giti, Emtiazi


    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

  19. ''Et sted''

    DEFF Research Database (Denmark)

    Dinesen, Cort Ross


    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...

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

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

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

  1. 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


    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.

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

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


    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.

  3. Molecular and culture dependent characterization of endolithic bacteria in two beach sand samples and description of Rhizobium endolithicum sp. nov. (United States)

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


    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)).

  4. Rhizobium albus sp. nov., Isolated from Lake Water in Xiamen, Fujian Province of China. (United States)

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


    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)).

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


    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.

  6. Kinetics study of pyridine biodegradation by a novel bacterial strain, Rhizobium sp. NJUST18. (United States)

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


    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.

  7. Et evalueringseksperiment

    DEFF Research Database (Denmark)

    Christensen, Torben Spanget


    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...

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

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


    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.

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

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


    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.

  10. Underexpression of Ap from R-Plasmids in Fast-Growing Rhizobium Species (United States)

    Sikka, Virendra K.; Kumar, Sushil


    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

  11. Introduction of the Escherichia coli gdhA gene into Rhizobium phaseoli: effect on nitrogen fixation. (United States)

    Bravo, A; Becerril, B; Mora, J


    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

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


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


    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...

  13. Extracción de adn plasmidico de cepas de rhizobium leguminosarum

    Directory of Open Access Journals (Sweden)

    M. Y, Cortés L.


    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.

  14. Extracción de adn plasmidico de cepas de rhizobium leguminosarum



    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.

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


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


    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. Effects of microgravity on the binding of acetylsalicylic acid by Rhizobium leguminosarum bv. trifolii (United States)

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


    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.

  17. Et hjem

    DEFF Research Database (Denmark)

    Bruun, Maja Hojer


    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...

  18. 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.


    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

  19. 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.


    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

  20. Rhizobium qilianshanense sp. nov., a novel species isolated from root nodule of Oxytropis ochrocephala Bunge in China. (United States)

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


    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.

  1. 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


    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...

  2. Rhizobium hedysari sp. nov., a novel species isolated from a root nodule of Hedysarum multijugum in China. (United States)

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


    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.

  3. Studying Plant-Rhizobium Mutualism in the Biology Classroom: Connecting the Big Ideas in Biology through Inquiry (United States)

    Suwa, Tomomi; Williamson, Brad


    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…

  4. Production of Proteasome Inhibitor Syringolin A by the Endophyte Rhizobium sp. Strain AP16 (United States)

    Bigler, Laurent; Dudler, Robert


    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

  5. Mimosine Content of Leucaena leucocephala and the Sensitivity of Rhizobium to Mimosine. (United States)

    Mathews, A; Vittal Rai, P


    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.

  6. Isolation and characterization of an early colonizing Rhizobium sp. R8 from a household toilet bowl. (United States)

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


    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.

  7. Production of proteasome inhibitor syringolin A by the endophyte Rhizobium sp. strain AP16. (United States)

    Dudnik, Alexey; Bigler, Laurent; Dudler, Robert


    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.

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

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    Raposeiras Rui


    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.

  9. Symbiont shift towards Rhizobium nodulation in a group of phylogenetically related Phaseolus species. (United States)

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


    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.

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

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    Robledo M


    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.

  11. 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)


    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.

  12. 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


    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

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

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


    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.

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

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    Maqshoof Ahmad


    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.

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

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


    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.

  16. Isolation and characterization of Rhizobium meliloti mutants affected in exopolysaccharide production. (United States)

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


    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.

  17. 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


    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.

  18. Novel high- and low-copy stable cosmids for use in Agrobacterium and Rhizobium. (United States)

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


    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.

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


    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.

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


    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.

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


    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.

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

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    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.

  3. Functional characterization of aroA from Rhizobium leguminosarum with significant glyphosate tolerance in transgenic Arabidopsis. (United States)

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


    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.

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

    Kamberger, W


    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.

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

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    Tadeusz Zając


    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.

  6. 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

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    Isnia Aparecida de Oliveira


    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.

  7. 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


    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.

  8. Stimulation of indoleacetic acid production in a Rhizobium isolate of Vigna mungo by root nodule phenolic acids. (United States)

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


    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).

  9. 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)


    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.

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

    DEFF Research Database (Denmark)

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


    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...

  11. Inoculation of the nonlegume Capsicum annuum L. with Rhizobium strains. 2. Changes in sterols, triterpenes, fatty acids, and volatile compounds. (United States)

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


    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.

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


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


    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...

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


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


    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...

  14. Characterization of Rhizobium naphthalenivorans sp. nov. with special emphasis on aromatic compound degradation and multilocus sequence analysis of housekeeping genes. (United States)

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


    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).

  15. 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


    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.

  16. Two rhizobacterial strains, individually and in interactions with Rhizobium sp., enhance fusarial wilt control, growth, and yield in pigeon pea. (United States)

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


    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.

  17. 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)



    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.

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



    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...

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

    Directory of Open Access Journals (Sweden)



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

  20. 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


    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

  1. Characterization of the urease gene cluster from Rhizobium leguminosarum bv. viciae. (United States)

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


    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.

  2. Alfalfa Enod12 genes are differentially regulated during nodule development by Nod factors and Rhizobium invasion. (United States)

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


    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

  3. Azide resistance in Rhizobium ciceri linked with superior symbiotic nitrogen fixation. (United States)

    Bhaskar, V Vijay


    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.

  4. Effect of leguminous lectins on the growth of Rhizobium tropici CIAT899. (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


    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.

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

    Directory of Open Access Journals (Sweden)

    Mayron Alves de Vasconcelos


    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.

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

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


    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.

  7. The RPG gene of Medicago truncatula controls Rhizobium-directed polar growth during infection. (United States)

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


    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.

  8. Regulation of nitrogen metabolism is altered in a glnB mutant strain of Rhizobium leguminosarum. (United States)

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


    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.

  9. Production of extracellular biopolymers and identification of intracellular proteins and Rhizobium tropici. (United States)

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


    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.

  10. 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


    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)

  11. Molecular phylogenetic analysis of Rhizobium sullae isolated from Algerian Hedysarum flexuosum. (United States)

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


    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.

  12. Versatile properties of an exopolysaccharide R-PS18 produced by Rhizobium sp. PRIM-18. (United States)

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


    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.

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

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    Wood Thomas K


    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.

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

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    Araújo Ademir Sérgio Ferreira de


    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.

  15. 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.

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    Ormeño-Orrillo Ernesto


    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

  16. Projet Monica, enquête de population 1984/1985 dans les cantons de Vaud et Fribourg : rapport final sur l'analyse de la plombémie


    Berode, Michèle; Guillemin, Michel; Rickenbach, Martin; Wietlisbach, Vincent


    Le dosage du plomb sanguin a été inclus dans l'enquête MONICA (MONItoring of trends and determinants in CArdiovascular disease) sur un échantillon représentatif de la population des cantons de Fribourg et de Vaud. Les résultats sont présentés en trois sections: 1) Distribution de la plombémie en fonction de quelques variables spécifiques: variables socio-démographiques, facteurs de risque classiques des maladies cardio-vasculaires, variables sur certaines habitudes alimentaires; 2) Analyse di...

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


    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.

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


    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)).

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

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    Hélène Froquet


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

  20. Deduced products of C4-dicarboxylate transport regulatory genes of Rhizobium leguminosarum are homologous to nitrogen regulatory gene products.


    Ronson, C W; Astwood, P M; Nixon, B T; Ausubel, F M


    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...

  1. Identification and sequence analysis of the Rhizobium meliloti dctA gene encoding the C4-dicarboxylate carrier.


    Engelke, T; Jording, D; Kapp, D.; Pühler, A.


    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...

  2. Two-dimensional proteome reference map of Rhizobium tropici PRF 81 reveals several symbiotic determinants and strong resemblance with agrobacteria. (United States)

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


    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.



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


    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/...

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

    Glyan'ko, A K


    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.

  5. 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


    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.

  6. Isolation of Rhizobium phaseoli Tn5-induced mutants with altered expression of cytochrome terminal oxidases o and aa3. (United States)

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


    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

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

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    Sameh H. Youseif


    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

  8. Competition among rhizobium species for nodulation of Leucaena leucocephala in two tropical soils

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    Moawad, H.; Bohlool, B.B.


    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.

  9. Characterization of genes involved in erythritol catabolism in Rhizobium leguminosarum bv. viciae. (United States)

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


    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.

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

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    Krehenbrink Martin


    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

  11. Evaluation of diets containing silage of maniÃoba (Manihot pseudoglaziovii Pax. Et. K. Hoffman) during the final stage of goats in the brazilian semi-arid region


    Fernando Thomaz Medina


    The present work aimed to evaluate the consumption, the digestibility of nutrients, the daily average weight gain, the nutriment conversion, as well as the weight and yield of carcass of goats being held in confinement during the final stage, receiving diets containing silage of manioc associated to different energy sources. 15 goats without defined racial standard, not castrated, with initial average life weight of 21,0 kg, were allocated in delineation in casual blocks, with three tre...

  12. Study of vibrations and stabilization of linear collider final doublets at the sub-nanometer scale; Etude des vibrations et de la stabilisation a l'echelle sous-nanometrique des doublets finaux d'un collisionneur lineaire

    Energy Technology Data Exchange (ETDEWEB)

    Bolzon, B


    CLIC is one of the current projects of high energy linear colliders. Vertical beam sizes of 0.7 nm at the time of the collision and fast ground motion of a few nanometers impose an active stabilization of the final doublets at a fifth of nanometer above 4 Hz. The majority of my work concerned vibrations and active stabilization study of cantilever and slim beams in order to be representative of the final doublets of CLIC. In a first part, measured performances of different types of vibration sensors associated to an appropriate instrumentation showed that accurate measurements of ground motion are possible from 0.1 Hz up to 2000 Hz on a quiet site. Also, electrochemical sensors answering a priori the specifications of CLIC can be incorporated in the active stabilization at a fifth of nanometer. In a second part, an experimental and numerical study of beam vibrations enabled to validate the efficiency of the numerical prediction incorporated then in the simulation of the active stabilization. Also, a study of the impact of ground motion and of acoustic noise on beam vibrations showed that an active stabilization is necessary at least up to 1000 Hz. In a third part, results on the active stabilization of a beam at its two first resonances are shown down to amplitudes of a tenth of nanometer above 4 Hz by using in parallel a commercial system performing passive and active stabilization of the clamping. The last part is related to a study of a support for the final doublets of a linear collider prototype in phase of finalization, the ATF2 prototype. This work showed that relative motion between this support and the ground is below imposed tolerances (6 nm above 0.1 Hz) with appropriate boundary conditions. (author)

  13. Growth, nodulation and yield of mash bean (Vigna mungo L. as affected by Rhizobium inoculation and soil applied L-tryptophan

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    Muhammad Iqbal Hussain*, Muhammad Javed Akhtar, Hafiz Naeem Asghar and Maqshoof Ahmad


    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.

  14. 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 (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...

  15. 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 (United States)

    Fujiwara, Kazuki; Someya, Nobutaka; Shinohara, Makoto


    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

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


    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.

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

  18. 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))


    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.

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


    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.

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


    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.

  1. 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


    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.

  2. Rhizobium leguminosarum is the symbiont of lentils in the Middle East and Europe but not in Bangladesh. (United States)

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


    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.

  3. Recommendations for the management of old uranium mining sites in France. From Limousin sites to other sites, from short- to medium- and long-terms. Final report of the pluralist expertise group on Limousin uranium mines (GEP). Synthesis and final report; Recommandations pour la gestion des anciens sites miniers d'uranium en France. Des sites du Limousin aux autres sites, du court aux moyen et long termes. Rapport final du Groupe d'expertise pluraliste sur les mines d'uranium du Limousin (GEP). Synthese et Rapport final

    Energy Technology Data Exchange (ETDEWEB)



    The final report of the Pluralistic Experts Group for the Uranium mines of Limousin (GEP) brings together the main conclusions and recommendations arising from three and half years of work having mobilized, at the request and with the financial support of French authorities, more than forty experts from a varying range of disciplines and backgrounds. The mission given to GEP by the Ministers of Ecology, Industry and Health, as well as the President of the Nuclear safety Authority, was ambitious. It was not simply a matter of conducting an exhaustive and vigorous investigation of actual impacts, but also to analyse the present situation from a technical point of view starting with actual cases to clarify the options for management and monitoring, and to make recommendations on their development in order to reduce the current impacts and to foresee those in the long term according to the preparation of a long term plan. This final report attempts to develop a coherent framework of recommendations that are as operationally feasible as possible. Thus, the proposals of the GEP underline the need for an comprehensive approach, on the basis of work on the institutional perspectives, of a programme for improvement of knowledge and including a reinforcement of information and dialogue, to frame and guide the characterization of the risks and impacts, the evolution of the surveillance devices and the consolidation of the existing protection systems. These final proposals take account of a whole range of activities undertaken by Areva NC as well as the relevant local and national government organizations; and which integrate certain recommendations already produced by the GEP within the framework of its three interim reports. The GEP sets out six main areas of improvements, within which the GEP makes 15 major recommendations addressed to the public authorities, the owner and all of the stakeholders concerned. These recommendations, largely detailed in the report, aim to: - 1

  4. 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


    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

  5. 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


    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.

  6. 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


    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

  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. C. Petrone et al.: "Magnetic measurement of the model magnet QD0 designed for the CLIC final focus beam transport line." CERN TE-MSC Internal Note, EDMS Nr: 1184196

    CERN Document Server

    Arpaia, Pasquale; Petrone, Carlo; Russenschuck, Stephan; Walckiers, Louis


    This note presents the results of the magnetic measurements performed on QD0, model magnet for the final focus transport line for CLIC (Fig. 1). This high-gradient, hybrid quadrupole has a yoke length of 0.1 m and an aperture of 8.3 mm. ND2Fe14B Permanent magnet blocks provide a gradient of 150 T/m, which can be further increased to 530 T/m when the four coils are excited to 18.3 A. The request was to measure the strength of the field and the multipole coefficients at different currents. The measurement of the field strength, by means of the single stretched wire system, was done in December 2011 in the I8 laboratory. The measurement of the multipole was done by means of the oscillating wire system [1][2].

  9. Acetyl Coenzyme A Acetyltransferase of Rhizobium sp. (Cicer) Strain CC 1192. (United States)

    Kim, S A; Copeland, L


    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]) 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.

  10. 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


    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.

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

    Directory of Open Access Journals (Sweden)

    Serrano Larráyoz, Fernando


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

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

  12. 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


    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.

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

    Directory of Open Access Journals (Sweden)

    Jean-Louis Bacqué-Grammont


    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.

  14. Effect of Rhizobium and arbuscular mycorrhizal fungi inoculation on electrolyte leakage in Phaseolus vulgaris roots overexpressing RbohB. (United States)

    Arthikala, Manoj-Kumar; Nava, Noreide; Quinto, Carmen


    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.

  15. 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: [Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011 (Japan)


    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, 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.

  16. 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


    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.

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

    Institute of Scientific and Technical Information of China (English)


    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.

  18. New insights into Nod factor biosynthesis: Analyses of chitooligomers and lipo-chitooligomers of Rhizobium sp. IRBG74 mutants. (United States)

    Poinsot, Véréna; Crook, Matthew B; Erdn, Stéphanie; Maillet, Fabienne; Bascaules, Adeline; Ané, Jean-Michel


    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.

  19. Fluorescence studies with malate dehydrogenase from rhizobium japonicum 3I1B-143 bacteroids: a two-tryptophan containing protein (United States)

    Ghiron, Camillo A.; Eftink, Maurice R.; Waters, James K.; Emerich, David W.


    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.

  20. Say NO to ET. (United States)

    Vanhoutte, P M


    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.

  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 (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


    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. Impact of dual inoculation with Rhizobium and PGPR on growth and antioxidant status of Vicia faba L. under copper stress. (United States)

    Fatnassi, Imen Challougui; Chiboub, Manel; Saadani, Omar; Jebara, Moez; Jebara, Salwa Harzalli


    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.

  4. Greenhouse effect gases sources and sinks (CO{sub 2}, CH{sub 4}, N{sub 2}O) in grasslands and reduction strategies. Greenhouse effect gases prairies. Final report of the second part of the project. April 2004; Sources et puits de gaz a effet de serre (CO{sub 2}, CH{sub 4}, N{sub 2}O) en prairie paturee et strategies de reduction. GES-Prairies. Rapport final de la seconde tranche du projet. Avril 2004

    Energy Technology Data Exchange (ETDEWEB)

    Soussana, J.F


    The project 'GES-Prairies' (Greenhouse Gases - Grasslands) had two main objectives: 1. To measure more accurately the fluxes of CO{sub 2}, CH{sub 4} and N{sub 2}O of French grasslands and determine the greenhouse gas (GHG) balance of these areas. 2. To calculate the net GHG emissions of cattle production farms and finally to propose and evaluate some management scenarios leading to a reduction of GHG emissions. This project deals with three different spatial scales: the field scale, the farm scale and finally, the regional scale. At the field scale, during two years, fluxes of CO{sub 2}, CH{sub 4} and N{sub 2}O were measured in a mid-mountain permanent grassland, previously managed intensively by cutting and grazing (Laqueuille, Auvergne, France). Results from the first complete year of measurements show that the extensification process (reduction of the stocking rate and stopping N fertilization) allows to stock more carbon in the ecosystem. At the farm scale, We developed a model (FARMSIM, coupled to PASIM) able to simulate the GHG balance of a livestock farm. FARMSIM has been tested with data obtained from a mixed livestock farm in Lorraine (dairy and meat production, annual average stocking rate = 1.3 LU ha{sup -1}) of 100 ha (including 76 ha of grasslands and 21 of annual crops). The results indicate a net emission of 175 t equivalent C-CO{sub 2} for this farm. If expressed per unit of product, it represents 1.34 t equivalent C-CO{sub 2} per LU and per year or 0.54 kg CO{sub 2} per kg of milk and per year. At the regional scale/. The PASIM model has been used to simulate the European grasslands with a spatial resolution of 1' (about 200 * 200 km). For each grid cell, a sensibility analysis allowed to determine the N application which correspond to 30% of the N application that would maximize the annual yield of the pasture. Simulation runs on mixed systems (combining grazing and cutting) show that almost one half of the grassland area is, on

  5. Final report of the project. Emission of nitrogen oxides by the soils. Measures, modelization, land registry and inventory. Impact on the air quality, the climatic change and the evaluation of possibilities of these emissions reduction; Rapport final du projet. Emissions d'oxydes d'azote par les sols. Mesures, modelisation, cadastre et inventaire. Impact sur la qualite de l'air, le changement climatique, et evaluation des gisements de reduction de ces emissions

    Energy Technology Data Exchange (ETDEWEB)

    Serca, D.; Cortinovis, J. [LA Laboratoire d' Aerologie UMR 5560, 31 - Toulouse (France); Laville, P.; Gabrielle, B. [Institut National de Recherches Agronomiques (INRA), Environnement et Grandes Cultures, 78 - Thiverval-Grignon (France); Beekmann, M.; Ravetta, F. [Universite Pierre et Marie Curie, SA Service d' Aeronomie, 75 - Paris (France); Henault, C. [Institut National de Recherches Agronomiques (INRA-LMS) UMR Microbiologie des Sols-Geosol, 21 - Dijon (France)


    This project deals with NOx biosphere-atmosphere exchanges, NOx being considered as an indirect greenhouse gases (tropospheric O{sub 3} precursor). It relies on four laboratory specialized both on the soil-plant-atmosphere interface, and on the atmospheric chemistry. Methodology used bear on a set of in situ and laboratory measurements aiming at improving existing emission parameterization, or building new ones for the agro-ecosystems encountered in France or Europe. In situ measurements allowed to study the emission phenology in relation with relevant environmental parameters (meteorological, soil characteristics, and agricultural). Laboratory measurements allowed to establish an emission algorithm related to the three main parameters, that is, soil temperature, water and ammonia content. This algorithm has been adapted and simplified to spatialize the emissions at the France level. This spatialization was performed using environmental parameters accessible through data base (ECMWF) or agricultural statistics (such as nitrogen inputs, land use, crops). Spatial and temporal extrapolation allowed reaching the main objective, that is, to build a national inventory for a reference year (2002). This inventory allowed determining the contribution of NOx emitted by soil as compared to total emitted NOx, and the proportion of NOx emitted by soil due to fertilizer use. Our study, based on 57% of the French used agricultural area, and extrapolated to the whole arable surface, shows that soils would be responsible of about 5% of the total NOx emissions. On these 5%, 20%, which finally is a rather low percentage, would be linked to fertilizer use. The impact of these emissions on the atmospheric chemistry has been evaluated using the CHIMERE chemistry-transport model. We found that NOx emissions from soil would be of minor importance when compared to the industrial emissions, being a factor of ten lower in France. As a matter of consequence, the impact of the emissions on the

  6. Cultures et organisations

    NARCIS (Netherlands)

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


    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

  7. Et godt brand

    DEFF Research Database (Denmark)

    Christensen, Line Hjorth


    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)...

  8. 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...

  9. 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...

  10. Increase in osmotolerance of Rhizobium fredii soybean isolate BD32 by the proB proA operon of Escherichia coli. (United States)

    Neumivakin, L V; Solovjev, V P; Sokhansanj, A; Tilba, V A; Moseiko, N A; Shachbasian, R V; Piruzian, E S


    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.

  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


    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...... the expression pattern of VsENOD5, VsENOD12 and VsENOD40 during Rhizobium-induced nodule formation. Although the expression of these genes is largely similar to that of the pea counterparts, differences where found for the expression of VsENOD12 and VsENOD40 in Vicia. VsENOD12 is expressed in the whole...

  12. 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


    [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

  13. Tourisme et ressources naturelles



    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...

  14. The Nodulation of Alfalfa by the Acid-Tolerant Rhizobium sp. Strain LPU83 Does Not Require Sulfated Forms of Lipochitooligosaccharide Nodulation Signals▿ (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


    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

  15. Final Report

    Energy Technology Data Exchange (ETDEWEB)

    DeTar, Carleton [P.I.


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

  16. Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Gurney, Kevin R


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

  17. Rhizobium paranaense sp. nov., an effective N2-fixing symbiont of common bean (Phaseolus vulgaris L.) with broad geographical distribution in Brazil. (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


    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.

  18. Parler et convaincre

    CERN Document Server

    Vigner, Gérard


    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.

  19. Image et violence


    Nancy, Jean-Luc


    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...

  20. LYSnET

    DEFF Research Database (Denmark)

    Bønløkke Andersen, Kätte; Hansen, Ellen Katrine; Krogsbæk Mathiasen, Nanet

    2006-01-01 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 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....

  1. Ectopia lentis et pupillae

    Directory of Open Access Journals (Sweden)

    Fernanda Marcio


    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.

  2. Final Report

    DEFF Research Database (Denmark)

    Heiselberg, Per; Brohus, Henrik; Nielsen, Peter V.

    This final report for the Hybrid Ventilation Centre at Aalborg University describes the activities and research achievement in the project period from August 2001 to August 2006. The report summarises the work performed and the results achieved with reference to articles and reports published...

  3. Entrepreneuriat Social et Participation Citoyenne

    Directory of Open Access Journals (Sweden)

    Sophie Larivet


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

  4. Étude dans les états finals dileptoniques de différentes propriétés des paires top-antitop avec les détecteurs D0 et ATLAS; Study in the final states dileptoniques different properties of top-antitop pairs with D0 and ATLAS detectors

    Energy Technology Data Exchange (ETDEWEB)

    Deterre, Cecile [Univ. Pierre et Marie Curie, Paris (France)


    Studies of different properties of the top-antitop pairs in dileptonique final state are presented in this thesis. Two analyzes were conducted in different experiments: one to D0 at the Tevatron, the other in ATLAS at LHC. Both colliders are different, the measures undertaken are complementary to the top of the properties of the study. The first analysis, conducted in the D0 experiment was to make simultaneous measurements of the cross section for production of pairs of top-antitop and branching ratio t -> Wb This was carried out in the channel with a dileptonique batch of data corresponding to a brightness of 5.4 fb⁻¹. It was then combined with the measurement made in the semileptonique channel to obtain an accuracy of 8% over the cross section, comparable to the accuracy of theoretical calculations. The second analysis presented, conducted in the ATLAS experiment was to measure the top quark charge asymmetry in dileptonique channel with the data set recorded by ATLAS in 2011, or 4.7 fb⁻¹. The results were then combined with the results of semileptonique channel obtained with 1 fb⁻¹. We measure: AC (ttbar) = 0.029 ± 0.018 (stat.) ± 0.014 (syst.), Which is compatible with the standard model prediction of 0.004 ±- 0.001.

  5. Gérer et alerter

    Directory of Open Access Journals (Sweden)

    Valérie November


    Full Text Available Sur la base de deux événements d’inondation ayant touché récemment, dans des contextes politiques, organisationnels et hydrologiques bien différents, de nouveaux quartiers d’habitation, cet article rend compte des pratiques des acteurs impliqués dans des situations d’alerte et de crise en Suisse. Le recensement des acteurs – à travers leur rôle et leur place dans les mécanismes de préparation, d’alerte et de gestion –, ainsi que l’inventaire des documents mobilisés par ceux-ci, ont été réalisés dans les deux cas. Cette analyse a permis d’évaluer la gestion des événements, de déceler les changements organisationnels qui ont suivi les crises et de connaître la conception et le degré de formalisation du risque dont étaient dotés les différents acteurs avant et après les inondations. Plus encore, l’analyse a documenté les nouveaux processus d’alerte et de prévision qui ont été mis en place suite aux événements. Il s’avère ainsi que les épisodes d’inondation agissent de façon décisive sur la production de connaissances, à un degré variable selon les acteurs. Ces épisodes révèlent aussi parfois l’existence de connaissances « en attente » qui ne sont pas encore intégrées dans les procédures institutionnelles. Tant du point de vue de la prévision que de la gestion de la crise, ils permettent aussi de tester les canaux de l’information et de combler les déficits d’organisation, de collaboration et de sécurisation des dispositifs de communication. En outre, les risques et les crises liés aux inondations modifient les dynamiques et les politiques territoriales, conséquences du réajustement des réseaux d’acteurs. La mise en place de dispositifs d’intervention et de gestion de crise se montre cependant plus efficace que la refonte des dispositifs d’aménagement, généralement longue. Toutefois, la mémoire des événements se dégradant avec le temps, une inscription

  6. Drague et cruising

    Directory of Open Access Journals (Sweden)

    Emmanuel Redoutey


    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.

  7. Search for h and A neutral Higgs bosons in final states with 4 jets in the experimental data collected by DELPHI detector at LEP200; Recherche de bosons de higgs neutres h et A dans les etats finals a quatre jets, avec le detecteur DELPHI a LEP200

    Energy Technology Data Exchange (ETDEWEB)

    Boonekamp, M. [CEA/Saclay, Dept. d' Astrophysique, de la Physique des Particules, de la Physique Nucleaire et de l' Instrumentation Associee (DAPNIA), 91 - Gif-sur-Yvette (France)]|[Paris-7 Univ., 75 (France)


    Searches for Higgs bosons are presented in the framework of the standard model, of the minimal supersymmetric model, and of itsfirst extension. The data sample used has been collected by Delphi in 1997 and 1998, and represents an integrated luminosity of 212 pb{sup -1}. The final states considered are the bb-bar bb-bar decay of the e{sup +}e{sup -} {yields} hZ process. The methods used for the analyses and for the interpretation of their results are described, as well as the implementation of b-quark identification from leptonic decays. After a first selection, the discrimination between background and signal events is studied, and the most powerful quantities are combined into a single variable. The best signal sensitivity is obtained by a weighted counting of all events, where the weight of the events is defined on the basis of the single variable. An excess of data, encountered in the search for hZ, justifies a separate discussion. The main instrumental and theoretical uncertainties, from which this excess could originate, are discussed. It is shown that the majority of the events in excess do not correspond to a Higgs signal, and that it is difficult to understand the excess as a consequence of imperfect standard process simulation. The results of the searches allow to give limits on the masses of the Higgs bosons in the models under consideration. The data imply m{sub h}>93 GeV in the standard model. In the MSSM, one finds m{sub h}>82.4 GeV and m{sub h} >83.3 GeV, for any tan{beta}. On the simplest extension of the MSSM, the pseudoscalar mass parameter m{sub h} must be greater than 69 GeV for tan{beta} >1. No constraint is found for tan{beta} <1. All limits are given at 95% C.L. (author)

  8. Enfants, chercheurs et citoyens

    CERN Document Server

    Lederman, Leon


    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.

  9. Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Bauer, Susanne [Columbia Univ., New York, NY (United States)


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

  10. Molecular mechanisms of ETS transcription factor-mediated tumorigenesis. (United States)

    Kar, Adwitiya; Gutierrez-Hartmann, Arthur


    The E26 transformation-specific (ETS) family of transcription factors is critical for development, differentiation, proliferation and also has a role in apoptosis and tissue remodeling. Changes in expression of ETS proteins therefore have a significant impact on normal physiology of the cell. Transcriptional consequences of ETS protein deregulation by overexpression, gene fusion, and modulation by RAS/MAPK signaling are linked to alterations in normal cell functions, and lead to unlimited increased proliferation, sustained angiogenesis, invasion and metastasis. Existing data show that ETS proteins control pathways in epithelial cells as well as stromal compartments, and the crosstalk between the two is essential for normal development and cancer. In this review, we have focused on ETS factors with a known contribution in cancer development. Instead of focusing on a prototype, we address cancer associated ETS proteins and have highlighted the diverse mechanisms by which they affect carcinogenesis. Finally, we discuss strategies for ETS factor targeting as a potential means for cancer therapeutics.

  11. La balle et la plume

    Directory of Open Access Journals (Sweden)

    Peter Marquis


    Full Text Available Fin octobre 2008, la nouvelle fit l’effet d’une bombe : Barack Obama, alors candidat à la présidence américaine, demanda à la chaîne câblée Fox News de retarder le début du sixième match de la World Series de base-ball afin de diffuser un spot de campagne. Son adversaire, John McCain, soutenu par le camp républicain et une partie de la population, monta aussitôt au créneau pour dénoncer l’hérésie : s’arroger le droit de perturber cette grande finale du championnat au déroulement immuable reve...

  12. ETS fusion genes in prostate cancer. (United States)

    Gasi Tandefelt, Delila; Boormans, Joost; Hermans, Karin; Trapman, Jan


    Prostate cancer is very common in elderly men in developed countries. Unravelling the molecular and biological processes that contribute to tumor development and progressive growth, including its heterogeneity, is a challenging task. The fusion of the genes ERG and TMPRSS2 is the most frequent genomic alteration in prostate cancer. ERG is an oncogene that encodes a member of the family of ETS transcription factors. At lower frequency, other members of this gene family are also rearranged and overexpressed in prostate cancer. TMPRSS2 is an androgen-regulated gene that is preferentially expressed in the prostate. Most of the less frequent ETS fusion partners are also androgen-regulated and prostate-specific. During the last few years, novel concepts of the process of gene fusion have emerged, and initial experimental results explaining the function of the ETS genes ERG and ETV1 in prostate cancer have been published. In this review, we focus on the most relevant ETS gene fusions and summarize the current knowledge of the role of ETS transcription factors in prostate cancer. Finally, we discuss the clinical relevance of TMRPSS2-ERG and other ETS gene fusions in prostate cancer.

  13. Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Stinis, Panos [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)


    This is the final report for the work conducted at the University of Minnesota (during the period 12/01/12-09/18/14) by PI Panos Stinis as part of the "Collaboratory on Mathematics for Mesoscopic Modeling of Materials" (CM4). CM4 is a multi-institution DOE-funded project whose aim is to conduct basic and applied research in the emerging field of mesoscopic modeling of materials.

  14. cancer et techniques innovantes



    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...

  15. Financiarisation et travail


    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


    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...

  16. Zoos et cause animale


    Joulian, Frédéric; Abegg, Christophe


    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 ...

  17. Artaud et les Tarahumaras

    Directory of Open Access Journals (Sweden)

    Marta Mariasole Raimondi


    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...

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


    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.

  19. Multiplicity of Sulfate and Molybdate Transporters and Their Role in Nitrogen Fixation in Rhizobium leguminosarum bv. viciae Rlv3841. (United States)

    Cheng, Guojun; Karunakaran, Ramakrishnan; East, Alison K; Poole, Philip S


    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.

  20. 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)


    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.

  1. 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


    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.

  2. Transgenic Leucaena leucocephala expressing the Rhizobium gene pydA encoding a meta-cleavage dioxygenase shows reduced mimosine content. (United States)

    Jube, Sandro L R; Borthakur, Dulal


    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 and a pyruvate hydrolase (EC, 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.

  3. Biological control of crown gall on grapevine and root colonization by nonpathogenic Rhizobium vitis strain ARK-1. (United States)

    Kawaguchi, Akira


    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.

  4. Relevance of fucose-rich extracellular polysaccharides produced by Rhizobium sullae strains nodulating Hedysarum coronarium l. legumes. (United States)

    Gharzouli, Razika; Carpéné, Marie-Anne; Couderc, François; Benguedouar, Ammar; Poinsot, Véréna


    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.

  5. 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.

  6. 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


    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.

  7. 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


    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.

  8. 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


    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.

  9. Light regulates attachment, exopolysaccharide production, and nodulation in Rhizobium leguminosarum through a LOV-histidine kinase photoreceptor. (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


    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.

  10. Characterisation of SalRAB a salicylic acid inducible positively regulated efflux system of Rhizobium leguminosarum bv viciae 3841. (United States)

    Tett, Adrian J; Karunakaran, Ramakrishnan; Poole, Philip S


    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.

  11. 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


    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.

  12. 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


    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)

  13. Protestantisme et bonapartisme


    Encrevé, Andre


    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...

  14. Lipochimie et innovations

    Directory of Open Access Journals (Sweden)

    Alfos Carine


    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


    Bonilla, Elisa; Sánchez, Armando; Rojano, Teresa; Chamizo, José Antonio


    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. Hvad karakteriserer et talent?

    DEFF Research Database (Denmark)

    Raalskov, Jesper


    Debatten i medierne har i stigende grad fokus på talentfulde medarbejdere - men hvad er talent egentlig? I den akademiske litteratur inden for Talent Management (TM) gives der mange forskellige bud på, hvordan man som virksomhed kan udvikle og lede talenter, men færre af feltets inputgivere...... forholder sig til, hvad den overordnede definition af talent er. Der ses i litteraturen divergerende opfattelser af, hvilke konkrete egenskaber (attributter) som definerer et talent. I denne artikel gives et bud på en konsensusskabende tilgang til talent, idet talent kan ses som; det du har gjort (fortid...

  17. Confiance, pouvoir et opportunisme

    Directory of Open Access Journals (Sweden)

    Sébastien Lupo


    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...

  18. Aspects Technologiques et Developpementaspects Technologiques et Developpement

    Directory of Open Access Journals (Sweden)

    Sebedio Jean-Louis


    Full Text Available L’acide linoléique conjugué (CLA est présent dans les aliments d’origine animale, en particulier ceux issus des ruminants. Le CLA peut aussi être synthétisé au laboratoire par isomérisation alcaline de l’acide linoléique. Alors que l’isomère naturel est le 18 : 2 9c,11t, les produits de synthèse contiennent principalement deux isomères, les 18 : 2 9c,11t et 10t,12c. De nombreuses études menées sur des modèles animaux, le plus souvent avec des mélanges synthétiques, montrent des effets potentiellement bénéfiques pour la santé (anticarcinogènes, protecteurs vis-à-vis de l’athérosclérose, modulateurs de la composition corporelle… alors que la plupart des études menées chez l’homme concernent les effets des CLA sur la composition corporelle. À ce jour, les données concernant les effets sur la composition corporelle chez l’homme semblent indiquer un bénéfice potentiel, mais les résultats restent controversés. Par ailleurs, bien qu’un effet anticarcinogène soit démontré chez l’animal, aucune étude chez l’homme n’a pu établir de relation entre CLA et cancer du sein. De plus, peu d’études traitant des aspects sécuritaires liés à la consommation à long terme ont été publiées. Par conséquent, il est nécessaire de disposer de plus de données en particulier chez l’Homme pour garantir l’innocuité de ces acides gras afin de protéger le consommateur, avant d’envisager l’utilisation de CLA dans des aliments fonctionnels.

  19. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Jarillo-Herrero, Pablo [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)


    This is the final report of our research program on electronic transport experiments on Topological Insulator (TI) devices, funded by the DOE Office of Basic Energy Sciences. TIbased electronic devices are attractive as platforms for spintronic applications, and for detection of emergent properties such as Majorana excitations , electron-hole condensates , and the topological magneto-electric effect . Most theoretical proposals envision geometries consisting of a planar TI device integrated with materials of distinctly different physical phases (such as ferromagnets and superconductors). Experimental realization of physics tied to the surface states is a challenge due to the ubiquitous presence of bulk carriers in most TI compounds as well as degradation during device fabrication.

  20. Un nouvel habitat du Bronze final IIIb dans le Val d’Orléans et ses traces de métallurgie du fer : Bonnée, Les Terres à l’Est du Bourg (Centre, Loiret A new settlement from late Bronze IIIb in the val d’Orléans: Bonnée, Les Terres à l’Est du Bourg (lands to the east of the town (Centre, Loiret

    Directory of Open Access Journals (Sweden)

    Stéphane Joly


    Full Text Available La multiplication récente des diagnostics archéologiques autour du petit bourg actuel de Bonnée a permis la détection d’une occupation du Bronze final IIIb (circa 900-750 av. n.-e. sur environ un hectare aux Terres à l’Est du Bourg. Les limites inhérentes à ce type d’intervention réduisent l’interprétation des structures et toute approche spatiale de ce probable habitat repéré. L’étude conjointe des différents mobiliers en particulier céramique et métallurgique, mais aussi le torchis et la faune, atteste de sa culture matérielle et de son intérêt. Ces scories pourraient être parmi les plus anciennes traces en région Centre d’activité métallurgique du fer. Des activités de post-réduction sont avérées et certaines opérations de forgeage sont supposées.La découverte de cet habitat dans ce secteur du lit majeur de la Loire, apporte de nouvelles données concernant l’occupation du sol et ses problématiques évolutives dans le Val d’Orléans sur ces périodes de transition avec le Hallstatt ancien.The recent increase in the archaeological evaluations around the village of Bonnée has enabled the discovery of a final Bronze Age IIIb settlement (circa 900-750 BP on about a hectare of the Terres à l’Est du Bourg. The limits inherent in this type of work restrict the interpretation of structures and all spatial approaches to this likely dwelling. The joint study of the different furnishings, in particular ceramics and metal, but also the cob and fauna, attests to its material culture and its interest. The slag could be amongst the oldest iron metallurgy remains from the Centre region. Some activities of post-forging are proven and certain operations are guessed at. The discovery of this settlement in this sector of the major bed of the Loire, has produced new data concerning the occupation of the land and its evolutionary problems in the valley of Orleans over these periods of transition in the early

  1. 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


    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.

  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. 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....

  4. Diversity of Plasmid Profiles and Conservation of Symbiotic Nitrogen Fixation Genes in Newly Isolated Rhizobium Strains Nodulating Sulla (Hedysarum coronarium L.). (United States)

    Mozo, T; Cabrera, E; Ruiz-Argüeso, T


    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.

  5. 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. (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


    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.

  6. Theories and calculation methods for regional objective ET (evapotranspiration): Applications

    Institute of Scientific and Technical Information of China (English)

    LIU diaHong; QIN DaYong; WANG MingNa; L(U) JinYan; SANG XueFeng; ZHANG RuiMei


    The regional objective ET (evapotranspiration) is defined as the quantity of water that could be con-sumed in a particular region. It varies with the water conditions and economic development stages in the region. It is also constrained by the requirement of benign environment cycle. At the same time, it must meet the demands of sustainable economic growth and the construction of harmony society.Objective ET based water resources distribution will replace the conventional method, which empha-sizes the balance between the water demand and the water supply. It puts focus on the reasonable water consumption instead of the forecasted water demand, which is usually greater than the actual one. In this paper, we calculated the objective ET of 2010 year level in Tianjin by an analysis-integra-tion-assessment method. Objective ET can be classified into two parts: controllable ET and uncontrol-lable ET. Controllable ET includes the ET from irrigation land and the ET from resident land, among which the former can be calculated with soil moisture model and evapotranspiration model, while the latter can be calculated by water use ration and water consumption rate. The uncontrollable ET can be calculated with the distributed hydrological model and the remote sensing monitoring model. The two models can be mutually calibrated. In this paper, eight schemes are put forward based on different portfolios of water resources. The objective ET of each scheme was calculated and the results were assessed and analyzed. Finally, an optimal scheme was recommended.

  7. A 13C-NMR study of exopolysaccharide synthesis in Rhizobium meliloti Su47 strain (United States)

    Tavernier, P.; Portais, J.-C.; Besson, I.; Courtois, J.; Courtois, B.; Barbotin, J.-N.


    Metabolic pathways implied in the synthesis of succinoglycan produced by the Su47 strain of R. meliloti were evaluated by 13C-NMR spectroscopy after incubation with [1{-}13C] or [2{-}13C] glucose. The biosynthesis of this polymer by R. meliloti from glucose occurred by a direct polymerisation of the introduced glucose and by the pentose phosphate pathway. Les voies métaboliques impliquées dans la synthèse du succinoglycane produit par la souche Su47 de R. meliloti ont été évaluées par la spectroscopie de RMN du carbone 13 après incubation des cellules avec du [1{-}13C] ou [2{-}13C] glucose. La biosynthèse de ce polymère à partir du glucose se produit par polymérisation directe du glucose et par la voie des pentoses phosphate.

  8. 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


    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.

  9. Symbiotic nitrogen fixation by a nifA deletion mutant of Rhizobium meliloti: the role of an unusual ntrC allele.


    Labes, M; Rastogi, V; Watson, R.; Finan, T M


    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...

  10. Interacción simbiótica Rhizobium-leguminosas arbóreas en sistemas contaminados con hidrocarburos policíclicos aromáticos.


    López Ortiz, Carlos


    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...

  11. 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


    [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.

  12. 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


    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

  13. Gestion et mondialisation

    Directory of Open Access Journals (Sweden)

    Jean-Luc Metzger


    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...

  14. Comique et pyrotechnie


    Feindt, Hendrik


    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...

  15. Et bedre image

    DEFF Research Database (Denmark)

    Vestergaard, Hedvig; Haagerup, Christian Deichmann


    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. Management et reconnaissance




    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...

  17. Conclusion et discussion


    Bertrand, Romain; Wachtel, Nathan; Berger, Laurent; Levi, Giovanni; Boucheron, Patrick; Calvo, Thomas


    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,...

  18. Femmes, militance et vieillissement

    Directory of Open Access Journals (Sweden)

    Anne Quéniart


    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

  19. Cyrano et les hydropotes

    Directory of Open Access Journals (Sweden)

    Alain Mothu


    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 ...

  20. 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...

  1. Candide et le physicien

    CERN Document Server

    Espagnat, Bernard d'


    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...

  2. Compatibility of rhizobial genotypes within natural populations of Rhizobium leguminosarum biovar viciae for nodulation of host legumes. (United States)

    Laguerre, Gisèle; Louvrier, Philippe; Allard, Marie-Reine; Amarger, Noëlle


    Populations of Rhizobium leguminosarum biovar viciae were sampled from two bulk soils, rhizosphere, and nodules of host legumes, fava bean (Vicia faba) and pea (Pisum sativum) grown in the same soils. Additional populations nodulating peas, fava beans, and vetches (Vicia sativa) grown in other soils and fava bean-nodulating strains from various geographic sites were also analyzed. The rhizobia were characterized by repetitive extragenomic palindromic-PCR fingerprinting and/or PCR-restriction fragment length polymorphism (RFLP) of 16S-23S ribosomal DNA intergenic spacers as markers of the genomic background and PCR-RFLP of a nodulation gene region, nodD, as a marker of the symbiotic component of the genome. Pairwise comparisons showed differences among the genetic structures of the bulk soil, rhizosphere, and nodule populations and in the degree of host specificity within the Vicieae cross-inoculation group. With fava bean, the symbiotic genotype appeared to be the preponderant determinant of the success in nodule occupancy of rhizobial genotypes independently of the associated genomic background, the plant genotype, and the soil sampled. The interaction between one particular rhizobial symbiotic genotype and fava bean seems to be highly specific for nodulation and linked to the efficiency of nitrogen fixation. By contrast with bulk soil and fava bean-nodulating populations, the analysis of pea-nodulating populations showed preferential associations between genomic backgrounds and symbiotic genotypes. Both components of the rhizobial genome may influence competitiveness for nodulation of pea, and rhizosphere colonization may be a decisive step in competition for nodule occupancy.

  3. Involvement of diamine oxidase and peroxidase in insolubilization of the extracellular matrix: implications for pea nodule initiation by Rhizobium leguminosarum. (United States)

    Wisniewski, J P; Rathbun, E A; Knox, J P; Brewin, N J


    Rhizobium leguminosarum colonizes host cells and tissues through infection threads, which are tubular in-growths of the plant cell wall. Monoclonal antibody MAC265 recognizes a plant matrix glycoprotein (MGP) associated with the lumen of these infection threads. This glycoprotein is also released in soluble form from the root tips of pea seedlings. In the presence of hydrogen peroxide, release of glycoprotein from root tips was not observed. Extractability from root tips was therefore used as the basis for investigating the peroxide-driven insolubilization of MGP and the possible involvement of two extracellular enzymes, peroxidase (POD) and diamine oxidase (DAO), was investigated. Release of MGP from root tips was enhanced by application of POD and DAO inhibitors (salicylhydroxamic acid and o-phenanthroline, respectively). Furthermore, release of MGP was inhibited by pretreatment of roots with putrescine (the substrate of DAO) and also by application of a partially purified extract of DAO from pea shoots. Following inoculation of pea roots with R. leguminosarum, elevated levels of DAO transcript were observed by reverse transcriptase-polymerase chain reaction (RT-PCR), but these then dropped to a low level from 4 to 10 days post inoculation, rising again in more mature nodules. In situ hybridization studies indicated that the bulk of the transcription was associated with the infected tissue in the center of the nodule. On the basis of these observations, we postulate that DAO may be involved in the peroxide-driven hardening of MGP in the lumen of infection threads and in the intercellular matrix.

  4. Nodulation of cowpeas and survival of cowpeas Rhizobia in acid, aluminum-rich soils. [Vigna unguiculata; Rhizobium

    Energy Technology Data Exchange (ETDEWEB)

    Hartel, P.G.; Whelan, A.M.; Alexander, M.


    A study was undertaken to determine whether the reduced nodulation of cowpeas (Vigna unguiculata (L.) Walp) grown in certain acid, Alrich soils resulted from the poor survival of the potentially infective rhizobia. Two strains of Rhizobium capable of nodulating cowpeas were used. The lowest pH for growth in defined liquid medium was 4.2 for one strain and 3.9 for the other. Only the latter was Al tolerant and could grow in a defined liquid medium containing 50 KAl(SO/sub 4/)/sub 2/. The survival of the bacteria and their ability to nodulate cowpeas in three soils were measured after the soils were amended with Ca or Al salts to give pH values ranging from 5.7 to 4.1 and extractable-Al concentrations from < 0.1 to 3.7 cmol(p/sup +/)/kg of soil. Only small differences in survival in 7 or 8 weeks were noted between the two strains. Plants inoculated with the Al-sensitive strain bore significantly fewer nodules in the more acid, Al-rich soils than in the same soils with higher pH values and less extractable Al. No significant reduction in nodule number was evident for plants inoculated with the Al-tolerant strain and grown in the more acid, Al-rich soils compared to cowpeas grown in the same soils with higher pH values and less extractable Al. It is suggested that the Al content of soil is not a major factor in the survival of cowpea rhizobia but that it does have a significant effect on nodulation. 24 references, 3 figures, 2 tables.

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

    Vozza, Nicolás F.; Abdian, Patricia L.; Russo, Daniela M.; Mongiardini, Elías J.; Lodeiro, Aníbal R.; Molin, Søren; Zorreguieta, Angeles


    In natural environments most bacteria live in multicellular structures called biofilms. These cell aggregates are enclosed in a self-produced polymeric extracellular matrix, which protects the cells, provides mechanical stability and mediates cellular cohesion and adhesion to surfaces. Although 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 the synthesis of the acidic exopolysaccharide and the PrsDE secretion system to develop a mature biofilm. PrsDE is responsible for the secretion of the Rap family of proteins that share one or two Ra/CHDL (cadherin-like-) domains. RapA2 is a calcium-dependent lectin with a cadherin-like β sheet structure that specifically recognizes the exopolysaccharide, either as a capsular polysaccharide (CPS) or in its released form [extracellular polysaccharide (EPS)]. In this study, using gain and loss of function approaches combined with phenotypic and microscopic studies we demonstrated that RapA lectins are involved in biofilm matrix development and cellular cohesion. While the absence of any RapA protein increased the compactness of bacterial aggregates, high levels of RapA1 expanded distances between cells and favored the production of a dense matrix network. Whereas endogenous RapA(s) are predominantly located at one bacterial pole, we found that under overproduction conditions, RapA1 surrounded the cell in a way that was reminiscent of the capsule. Accordingly, polysaccharide analyses showed that the RapA lectins promote CPS formation at the expense of lower EPS production. Besides, polysaccharide analysis suggests that RapA modulates the EPS size profile. Collectively, these results show that the interaction of RapA lectins with the polysaccharide is involved in rhizobial

  6. Evidence of transfer by conjugation of type IV secretion system genes between Bartonella species and Rhizobium radiobacter in amoeba.

    Directory of Open Access Journals (Sweden)

    Watcharee Saisongkorh

    Full Text Available BACKGROUND: Bartonella species cospeciate with mammals and live within erythrocytes. Even in these specific niches, it has been recently suggested by bioinformatic analysis of full genome sequences that Lateral Gene Transfer (LGT may occur but this has never been demonstrated biologically. Here we describe the sequence of the B. rattaustraliani (AUST/NH4(T circular plasmid (pNH4 that encodes the tra cluster of the Type IV secretion system (T4SS and we eventually provide evidence that Bartonella species may conjugate and exchange this plasmid inside amoeba. PRINCIPAL FINDINGS: The T4SS of pNH4 is critical for intracellular viability of bacterial pathogens, exhibits bioinformatic evidence of LGT among bacteria living in phagocytic protists. For instance, 3 out of 4 T4SS encoding genes from pNH4 appear to be closely related to Rhizobiales, suggesting that gene exchange occurs between intracellular bacteria from mammals (bartonellae and plants (Rhizobiales. We show that B. rattaustraliani and Rhizobium radiobacter both survived within the amoeba Acanthamoeba polyphaga and can conjugate together. Our findings further support the hypothesis that tra genes might also move into and out of bacterial communities by conjugation, which might be the primary means of genomic evolution for intracellular adaptation by cross-talk of interchangeable genes between Bartonella species and plant pathogens. CONCLUSIONS: Based on this, we speculate that amoeba favor the transfer of genes as phagocytic protists, which allows for intraphagocytic survival and, as a consequence, promotes the creation of potential pathogenic organisms.

  7. Influence of Lime and Phosphate on Nodulation of Soil-Grown Trifolium subterraneum L. by Indigenous Rhizobium trifolii. (United States)

    Almendras, A S; Bottomley, P J


    Previous research had identified four serogroups of Rhizobium trifolii indigenous to the acidic Abiqua soil (fine, mixed, mesic Cumulic Ultic Haploxeroll). Nodulation of subterranean clover (Trifolium subterraneum L.) by two of the serogroups, 6 and 36, was differentially influenced by an application of CaCO(3) which raised the pH of the soil from 5.0 to 6.5. These studies were designed to characterize this phenomenon more comprehensively. Liming the soil with either CaCO(3), Ca(OH)(2), MgO, or K(2)CO(3) significantly (P = 0.05) increased the percent nodule occupancy by serogroup 36, whereas the percent nodule occupancy by serogroup 6 was decreased, but the decrease was significant (P = 0.05) only after application of either CaCO(3) or Ca(OH)(2). Application of KH(2)PO(4) (25 mg of P kg of soil), which did not change soil pH, also significantly (P = 0.05) increased the percent nodule occupancy by serogroup 36. Application of KH(2)PO(4) in combination with Ca(OH)(2) produced the same increase in nodule occupancy by serogroup 36 as did individual application of the two materials. Soil populations of serogroup 36 consistently, and in the majority of cases significantly (P = 0.05), outnumbered those of serogroup 6 before planting and after harvest regardless of soil treatment or the outcome of nodulation. Soil chemical and plant analyses provided no evidence that liming was simulating phosphate addition by increasing the availability and subsequent uptake of soil P(i) by the subclover plants. Liming did, however, result in a significant transformation (30 to 50 mg of P kg of soil) of P(i) from the residual soil P(i) fraction into an NaOH-extractable organic P fraction during the preplant equilibration period.

  8. Influence of Lime and Phosphate on Nodulation of Soil-Grown Trifolium subterraneum L. by Indigenous Rhizobium trifolii† (United States)

    Almendras, Angela S.; Bottomley, Peter J.


    Previous research had identified four serogroups of Rhizobium trifolii indigenous to the acidic Abiqua soil (fine, mixed, mesic Cumulic Ultic Haploxeroll). Nodulation of subterranean clover (Trifolium subterraneum L.) by two of the serogroups, 6 and 36, was differentially influenced by an application of CaCO3 which raised the pH of the soil from 5.0 to 6.5. These studies were designed to characterize this phenomenon more comprehensively. Liming the soil with either CaCO3, Ca(OH)2, MgO, or K2CO3 significantly (P = 0.05) increased the percent nodule occupancy by serogroup 36, whereas the percent nodule occupancy by serogroup 6 was decreased, but the decrease was significant (P = 0.05) only after application of either CaCO3 or Ca(OH)2. Application of KH2PO4 (25 mg of P kg of soil−1), which did not change soil pH, also significantly (P = 0.05) increased the percent nodule occupancy by serogroup 36. Application of KH2PO4 in combination with Ca(OH)2 produced the same increase in nodule occupancy by serogroup 36 as did individual application of the two materials. Soil populations of serogroup 36 consistently, and in the majority of cases significantly (P = 0.05), outnumbered those of serogroup 6 before planting and after harvest regardless of soil treatment or the outcome of nodulation. Soil chemical and plant analyses provided no evidence that liming was simulating phosphate addition by increasing the availability and subsequent uptake of soil Pi by the subclover plants. Liming did, however, result in a significant transformation (30 to 50 mg of P kg of soil−1) of Pi from the residual soil Pi fraction into an NaOH-extractable organic P fraction during the preplant equilibration period. PMID:16347431

  9. PssP2 is a polysaccharide co-polymerase involved in exopolysaccharide chain-length determination in Rhizobium leguminosarum.

    Directory of Open Access Journals (Sweden)

    Małgorzata Marczak

    Full Text Available Production of extracellular polysaccharides is a complex process engaging proteins localized in different subcellular compartments, yet communicating with each other or even directly interacting in multicomponent complexes. Proteins involved in polymerization and transport of exopolysaccharide (EPS in Rhizobium leguminosarum are encoded within the chromosomal Pss-I cluster. However, genes implicated in polysaccharide synthesis are common in rhizobia, with several homologues of pss genes identified in other regions of the R. leguminosarum genome. One such region is chromosomally located Pss-II encoding proteins homologous to known components of the Wzx/Wzy-dependent polysaccharide synthesis and transport systems. The pssP2 gene encodes a protein similar to polysaccharide co-polymerases involved in determination of the length of polysaccharide chains in capsule and O-antigen biosynthesis. In this work, a mutant with a disrupted pssP2 gene was constructed and its capabilities to produce EPS and enter into a symbiotic relationship with clover were studied. The pssP2 mutant, while not altered in lipopolysaccharide (LPS, displayed changes in molecular mass distribution profile of EPS. Lack of the full-length PssP2 protein resulted in a reduction of high molecular weight EPS, yet polymerized to a longer length than in the RtTA1 wild type. The mutant strain was also more efficient in symbiotic performance. The functional interrelation between PssP2 and proteins encoded within the Pss-I region was further supported by data from bacterial two-hybrid assays providing evidence for PssP2 interactions with PssT polymerase, as well as glycosyltransferase PssC. A possible role for PssP2 in a complex involved in EPS chain-length determination is discussed.

  10. 紫云英根瘤菌应用效果研究%Application Effects of Rhizobium of Astragalus

    Institute of Scientific and Technical Information of China (English)

    刘英; 郭熙盛; 王允青; 唐杉; 曹卫东; 尹德柱; 郑进国


    [ Objective ] The research aimed to provide the theoretical basis for the improvement of soil fertility and the yield of Astragalus, and the recovery and the development of green manure production in Anhui. [ Method] The rhizobium matching with the local Astragalus varieties was screened by field experiment. [ Result ] Application of rhizobia was beneficial to the growth of Astragalus, and could increase the rate of nodulation. The rhizobia and the plants had symbiotic nitrogen-fixation, which made the seedling strong, and ensure Astragalus safe in winter. The rhizobia also promoted the vegetative growth of Astragalus, and increased the yield. [ Conclusion] The application effect of fungicide 4 was better than that of fungicide 1.%[目的]为培肥土壤、提高紫云英产量、恢复和发展安徽绿肥生产提供理论依据.[方法]通过田间试验,筛选与当地紫云英品种匹配的根瘤菌.[结果]施用根瘤菌有利于紫云英生长,增加结瘤率.根瘤菌与植株进行共生固氮,幼苗生长健壮,可确保紫云英安全越冬.根瘤菌能促进紫云英营养生长,对产量提高有一定的效果.[结论]4号菌剂的应用效果优于1号菌剂.

  11. Growth of cowpea plants inoculated with Rhizobium in a saline-sodic soil after application of gypsum

    Directory of Open Access Journals (Sweden)

    Angela Jessyka Pereira Brito Fontenele

    Full Text Available Two experiments were carried out with the aim of evaluating the growth of cowpea cultivated in saline-sodic soils corrected with gypsum: one experiment in the laboratory, to identify the best level of gypsum for the correction of the saline-sodic soils of the state of Pernambuco, Brazil; and the other in a greenhouse, after correction of the soils. As the test plant, the cowpea cultivar pele de moça, inoculated with Rhizobium strain BR3267 was used. The experiments were arranged in a randomised block design in a 2 x 5 factorial arrangement, two soils and five levels of the gypsum requirement (GR, equivalent to 50, 100, 150, 200 and 250% of the GR of the soil, as determined by the Schoonover M-1 method, with five replications. The following were evaluated: electrical conductivity of the soil saturation extract (EC, soil exchangeable sodium and percentage of soil exchangeable sodium (ESP, number of nodules (NN, nodule dry weight (NDW, shoot dry weight (SDW, shoot height (PH and nitrogen concentration (N in the shoots. Application of 100% of the GR, followed by the enough water for leaching, was effective for the correction of soil sodicity. The application of increasing levels of soil GR resulted in an increase in the number of nodules, dry weight of the nodules and shoots, and the height and levels of N absorbed by the plants in soil S2. In soil S1, the use of levels of 200 and 250% of soil the GR caused a decrease in all the variables under study.

  12. Interacción de Tsukamurella paurometabola C-924 con Rhizobium leguminosarum biovar phaseoli CFH en el cultivo de frijol

    Directory of Open Access Journals (Sweden)

    Marieta Marín Bruzos


    Full Text Available En el estudio se evaluaron, mediante análisis de los parámetros fenológicos de las plantas, la interacción de Tsukamurella paurometabola C-924 con Rhizobium leguminosarum biovar phaseoli CFH en el cultivo de frijol. Se emplearon cuatro tratamientos: plantas sin inocular (control, inoculadas con T. paurometabola C-924, inoculadas con R. leguminosarum biovar phaseoli CFH e inoculadas con ambas cepas. Se observaron diferencias significativas (P < 0.01 en los porcentajes de germinación de las plantas tratadas con microorganismos de forma independiente o conjunta con respecto al control sin inocular. Se determinó que la inoculación de T. paurometabola C-924 afectó el proceso de nodulación de R. leguminosarum biovar phaseoli CFH. Sin embargo, esto no incidió de manera significativa en la altura de las plantas ni en el diámetro del tallo, ya que no se encontraron diferencias entre los tratamientos para estos parámetros. Para el número de hojas, los mejores resultados se obtuvieron con la aplicación de T. paurometabola C-924. Se concluyó que la interacción de T. paurometabola C-924 con R. leguminosarum biovar phaseoli CFH en el frijol estimuló significativamente la germinación de las semillas y el número de hojas de las plantas con respecto al control sin inocular. Aunque la aplicación de T. paurometabola C-924 no favoreció la nodulación de R. leguminosarum biovar phaseoli CFH, esto no afectó las características fenológicas del cultivo.

  13. Rhizobium leguminosarum bv. trifolii rosR is required for interaction with clover, biofilm formation and adaptation to the environment

    Directory of Open Access Journals (Sweden)

    Piersiak Tomasz


    Full Text Available Abstract Background Rhizobium leguminosarum bv. trifolii is a symbiotic nitrogen-fixing bacterium that elicits nodules on roots of host plants Trifolium spp. Bacterial surface polysaccharides are crucial for establishment of a successful symbiosis with legumes that form indeterminate-type nodules, such as Trifolium, Pisum, Vicia, and Medicago spp. and aid the bacterium in withstanding osmotic and other environmental stresses. Recently, the R. leguminosarum bv. trifolii RosR regulatory protein which controls exopolysaccharide production has been identified and characterized. Results In this work, we extend our earlier studies to the characterization of rosR mutants which exhibit pleiotropic phenotypes. The mutants produce three times less exopolysaccharide than the wild type, and the low-molecular-weight fraction in that polymer is greatly reduced. Mutation in rosR also results in quantitative alterations in the polysaccharide constituent of lipopolysaccharide. The rosR mutants are more sensitive to surface-active detergents, antibiotics of the beta-lactam group and some osmolytes, indicating changes in the bacterial membranes. In addition, the rosR mutants exhibit significant decrease in motility and form a biofilm on plastic surfaces, which differs significantly in depth, architecture, and bacterial viability from that of the wild type. The most striking effect of rosR mutation is the considerably decreased attachment and colonization of root hairs, indicating that the mutation affects the first stage of the invasion process. Infection threads initiate at a drastically reduced rate and frequently abort before they reach the base of root hairs. Although these mutants form nodules on clover, they are unable to fix nitrogen and are outcompeted by the wild type in mixed inoculations, demonstrating that functional rosR is important for competitive nodulation. Conclusions This report demonstrates the significant role RosR regulatory protein plays in

  14. Mutation of praR in Rhizobium leguminosarum enhances root biofilms, improving nodulation competitiveness by increased expression of attachment proteins. (United States)

    Frederix, Marijke; Edwards, Anne; Swiderska, Anna; Stanger, Andrew; Karunakaran, Ramakrishnan; Williams, Alan; Abbruscato, Pamela; Sanchez-Contreras, Maria; Poole, Philip S; Downie, J Allan


    In Rhizobium leguminosarum bv. viciae, quorum-sensing is regulated by CinR, which induces the cinIS operon. CinI synthesizes an AHL, whereas CinS inactivates PraR, a repressor. Mutation of praR enhanced biofilms in vitro. We developed a light (lux)-dependent assay of rhizobial attachment to roots and demonstrated that mutation of praR increased biofilms on pea roots. The praR mutant out-competed wild-type for infection of pea nodules in mixed inoculations. Analysis of gene expression by microarrays and promoter fusions revealed that PraR represses its own transcription and mutation of praR increased expression of several genes including those encoding secreted proteins (the adhesins RapA2, RapB and RapC, two cadherins and the glycanase PlyB), the polysaccharide regulator RosR, and another protein similar to PraR. PraR bound to the promoters of several of these genes indicating direct repression. Mutations in rapA2, rapB, rapC, plyB, the cadherins or rosR did not affect the enhanced root attachment or nodule competitiveness of the praR mutant. However combinations of mutations in rapA, rapB and rapC abolished the enhanced attachment and nodule competitiveness. We conclude that relief of PraR-mediated repression determines a lifestyle switch allowing the expression of genes that are important for biofilm formation on roots and the subsequent initiation of infection of legume roots.

  15. Rhizobium leguminosarum bv. trifolii rosR is required for interaction with clover, biofilm formation and adaptation to the environment (United States)


    Background Rhizobium leguminosarum bv. trifolii is a symbiotic nitrogen-fixing bacterium that elicits nodules on roots of host plants Trifolium spp. Bacterial surface polysaccharides are crucial for establishment of a successful symbiosis with legumes that form indeterminate-type nodules, such as Trifolium, Pisum, Vicia, and Medicago spp. and aid the bacterium in withstanding osmotic and other environmental stresses. Recently, the R. leguminosarum bv. trifolii RosR regulatory protein which controls exopolysaccharide production has been identified and characterized. Results In this work, we extend our earlier studies to the characterization of rosR mutants which exhibit pleiotropic phenotypes. The mutants produce three times less exopolysaccharide than the wild type, and the low-molecular-weight fraction in that polymer is greatly reduced. Mutation in rosR also results in quantitative alterations in the polysaccharide constituent of lipopolysaccharide. The rosR mutants are more sensitive to surface-active detergents, antibiotics of the beta-lactam group and some osmolytes, indicating changes in the bacterial membranes. In addition, the rosR mutants exhibit significant decrease in motility and form a biofilm on plastic surfaces, which differs significantly in depth, architecture, and bacterial viability from that of the wild type. The most striking effect of rosR mutation is the considerably decreased attachment and colonization of root hairs, indicating that the mutation affects the first stage of the invasion process. Infection threads initiate at a drastically reduced rate and frequently abort before they reach the base of root hairs. Although these mutants form nodules on clover, they are unable to fix nitrogen and are outcompeted by the wild type in mixed inoculations, demonstrating that functional rosR is important for competitive nodulation. Conclusions This report demonstrates the significant role RosR regulatory protein plays in bacterial stress adaptation

  16. Co-inoculation of Rhizobium tropici and Azospirillum brasilense in common beans grown under two irrigation depths

    Directory of Open Access Journals (Sweden)

    Amanda Ribeiro Peres²*


    Full Text Available ABSTRACT The alternative technique of co-inoculation or mixed inoculation with symbiotic and non-symbiotic bacteria has been studied in leguminous plants. However, there are few field studies with common beans and under the influence of the amount of irrigated water. Thus, the objective of this study was to evaluate the efficiency of inoculation and co-inoculation of common beans with Rhizobium tropici and Azospirillum brasilense under two irrigation depths. The experiment was carried out in the winter of 2012 and 2013, in Selvíria, state of Mato Grosso do Sul. The experimental design was composed of randomized blocks in split-plot scheme with two irrigation depths in the plots (recommended for common beans and 75% of the recommended and five forms of nitrogen (N supply in the split-plots (control non-inoculated with 40 kg ha- 1 of N in topdressing, 80 kg ha- 1 of N in topdressing, A. brasilense inoculation with 40 kg ha-1 of N in topdressing, R. tropici inoculation with 40 kg ha-1 of N in topdressing, and co-inoculation of A. brasilense and R. tropici with 40 kg ha- 1 of N in topdressing with four repetitions. Co-inoculation increased nodulation in the second year of cultivation. None of the evaluated treatments increased the grain yield in relation to non-inoculated control with 40 kg ha-1 of nitrogen in topdressing, which presented average yield of 2,200 kg ha-1. The use of 75% of the recommended irrigation depth provides similar grain yield to the recommended irrigation depth in common beans cropped in winter.

  17. Biodegradation of Selected Nigerian Fruit Peels by the use of a Non-pathogenic Rhizobium species CWP G34B. (United States)

    Esther Boboye, Bolatito; Ajayi, George Olarewaju


    This study was carried out to determine the ability of Rhizobium species CWP G34B to degrade the peels of selected Nigerian fruits. The potential of the bacterium to digest some carbon sources (lactose, maltose, sucrose and mannitol) and peels of some Nigerian fruits (pineapple, orange, plantain, banana, pawpaw and mango fruits) was investigated by growing the organism on the substances separately after which DNSA reagent method was used to quantify glucose released into the medium. The results showed that the bacterium was able to degrade all the carbohydrates with the highest and the lowest glucose concentrations of 5.52 mg/ml for lactose and 0.50 mg/ml for mannitol. The carbohydrate-catabolic-enzyme (CCE) activity ranged from 0.169 mg/ml to 1.346 mg/ml glucose per mg/ml protein. Mannitol exhibited the highest CCE activity while the lowest activity was observed in the presence of sucrose. The amount of extracellular protein synthesized was highest (9.803 mg/ml) in the presence of maltose and lowest (0.925 mg/ml) in mannitol. The mean polygalacturonase activity was 0.54 unit/ml when the bacterium was grown in pectin in contrast to 0.28 unit/ml when it was grown in mannitol. The bacterium showed ability to breakdown the peels of the Nigerian fruits with the highest capability in banana and pineapple (0.42 and 0.41 mg/ml glucose per mg/ml protein respectively). The fruit-peel-degrading enzyme activity was lowest in orange peel (0.75 unit/ml).

  18. Final Report

    Energy Technology Data Exchange (ETDEWEB)

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


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

  19. Experimental Study of the Rhizobium and Iron Oxide Thiobacillus for Heap Leaching of Zinc Leaching Slag%根瘤菌与氧化铁硫杆菌堆浸锌浸出渣的试验研究

    Institute of Scientific and Technical Information of China (English)

    李勇; 邓兴; 金开胜; 杨光棣


    This paper adopts the rhizobium and thiobaeillus ferrooxidans respectively for heap leaching processing of hydrometallurgy of zinc leaching residue. Through the treatment of rhizobium with thiobacillus ferrooxidans, zinc leaching residue of zinc leaching rate is compared. The test results indicate that rhizobium treatment of zinc leaching residue of zinc leaching rate reaches 24.12 % and thiobacillus ferrooxidans treatment of zinc leaching residue of zinc leaching rate reaches 33.86 %. Treatment rate by thiobacillus ferrooxidans was significantly higher than that of rhizobium.%本文采用根瘤菌与氧化铁硫杆菌分别堆浸处理湿法冶金的锌浸出渣,通过比较根瘤菌与氧化铁硫杆菌处理的锌浸出渣的锌浸出率。试验结果表明,根瘤菌处理锌浸出渣锌浸出率达到了24.12%,而氧化铁硫杆菌处理的锌浸出渣锌浸出率达到了33.86%,氧化铁硫杆菌处理锌浸出渣的锌浸出率明显高于根瘤菌。


    Directory of Open Access Journals (Sweden)

    - Karti


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

  1. Characterization of a symbiotically effective Rhizobium resistant to arsenic: Isolated from the root nodules of Vigna mungo (L.) Hepper grown in an arsenic-contaminated field. (United States)

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


    Bacteria were isolated from the root nodules of Vigna mungo (L.) Hepper, grown in an arsenic-contaminated field and the strain was selected by its nodulation ability as well as better arsenic tolerant capacity compared to others. The selected strain was identified as Rhizobium by 16S rDNA sequencing and designated as VMA301. Phylogenetic analysis of the gene sequences showed its close relatedness with Sinorhizobium fredii. LC(50) value of arsenate for the bacteria as determined by flow cytometry was found to be 2.8 mM and arsenic uptake was measured by atomic absorption spectrometry as 0.048 mg g(-1) biomass. The high amount of arsenic was toxic to the cell, which changed the morphology of the bacteria to an elongated shape. Presence of a transcriptional regulatory gene (ArsR) of the ars genetic system was confirmed by amplification and sequencing. The symbiotic property of the isolate was also confirmed by amplification and sequencing of the NodC gene. These results indicate that the isolated Rhizobium bacteria may exert dual roles in the environment, arsenic bioremediation from the soil as well as increase of soil fertility through nitrogen fixation.

  2. Polymorphic infection and organogenesis patterns induced by a Rhizobium leguminosarum isolate from Lotus root nodules are determined by the host genotype. (United States)

    Gossmann, Jasmin A; Markmann, Katharina; Brachmann, Andreas; Rose, Laura E; Parniske, Martin


    To sample the natural variation in genes controlling compatibility in the legume-rhizobium symbiosis, we isolated rhizobia from nodules of endemic Lotus species from 21 sites across Europe. The majority of isolates were identified as Mesorhizobium- or Bradyrhizobium-related and formed nitrogen-fixing root nodules on Lotus corniculatus and L. pendunculatus, respectively, thus confirming previously defined cross-inoculation groups. Rhizobium leguminosarum (Rl) strain Norway, isolated from L. corniculatus nodules, displayed an exceptional phenotypic variation on different Lotus genotypes. On L. burttii, Rl Norway formed infected nodules, whereas tumors and elongated infected swellings were induced on L. glaber and L. japonicus ecotype Nepal, respectively. A symbiosis- and Nod-factor-responsive promoter:uidA fusion was strongly and rapidly induced in L. japonicus Gifu, but infection threads or signs of nodule organogenesis were absent. This complex phenotypic pattern was not mimicked by either of three engineered R. leguminosarum bv viciae strains producing different Nod-factor variants. Intriguingly, Rl Norway formed infection threads on Pisum sativum cv Sparkle, but failed to induce organogenesis. Rl Norway thus uncovered variation in symbiotic capabilities among diploid Lotus species and ecotypes that are obscured by optimally adapted M. loti strains. These contrasting infection and organogenesis phenotypes reveal recent diversification of recognition determinants in Lotus.

  3. Life in an arsenic-containing gold mine: genome and physiology of the autotrophic arsenite-oxidizing bacterium rhizobium sp. NT-26. (United States)

    Andres, Jérémy; Arsène-Ploetze, Florence; Barbe, Valérie; Brochier-Armanet, Céline; Cleiss-Arnold, Jessica; Coppée, Jean-Yves; Dillies, Marie-Agnès; Geist, Lucie; Joublin, Aurélie; Koechler, Sandrine; Lassalle, Florent; Marchal, Marie; Médigue, Claudine; Muller, Daniel; Nesme, Xavier; Plewniak, Frédéric; Proux, Caroline; Ramírez-Bahena, Martha Helena; Schenowitz, Chantal; Sismeiro, Odile; Vallenet, David; Santini, Joanne M; Bertin, Philippe N


    Arsenic is widespread in the environment and its presence is a result of natural or anthropogenic activities. Microbes have developed different mechanisms to deal with toxic compounds such as arsenic and this is to resist or metabolize the compound. Here, we present the first reference set of genomic, transcriptomic and proteomic data of an Alphaproteobacterium isolated from an arsenic-containing goldmine: Rhizobium sp. NT-26. Although phylogenetically related to the plant-associated bacteria, this organism has lost the major colonizing capabilities needed for symbiosis with legumes. In contrast, the genome of Rhizobium sp. NT-26 comprises a megaplasmid containing the various genes, which enable it to metabolize arsenite. Remarkably, although the genes required for arsenite oxidation and flagellar motility/biofilm formation are carried by the megaplasmid and the chromosome, respectively, a coordinate regulation of these two mechanisms was observed. Taken together, these processes illustrate the impact environmental pressure can have on the evolution of bacterial genomes, improving the fitness of bacterial strains by the acquisition of novel functions.

  4. Phylogeny and diversity of broad bean rhizobium in Qinghai%青海蚕豆根瘤菌的系统发育与多样性研究

    Institute of Scientific and Technical Information of China (English)

    韩梅; 马晓彤; 曹卫东; 张宏亮; 王雪翠


    To explore and exploit broad bean rhizobium of Qinghai, and determine their classification status.Broad bean rhizobia were collected in Qinghai and 16 SrDNA identification, phylogeny and diversity were studied.The results showed that 6 strains belonging to 4 groups respectively, andR. leguminosarum, R.laguerreae, R.fabae, R.pisi have the closest phylogenetic relationship.The species diversity is rich in Qinghai.%为发掘和利用青海冷凉地区蚕豆优良的根瘤菌种质资源,确定其分类地位.通过对青海冷凉地区采集的蚕豆根瘤菌进行16 SrDNA鉴定、系统发育及多样性研究.结果表明:6株供试菌株属于4个类聚,分别与Rhizobium leguminosarum,R.laguerreae,R.fabae,R.pisi亲缘关系最为接近,种类多样性较为丰富.

  5. 花生专用根瘤菌剂应用试验%Test on the Application of Special Peanut Rhizobium Agent

    Institute of Scientific and Technical Information of China (English)



    为探索根瘤菌剂在花生上的应用效果,寻求提高花生单产及促进农民增收的途径,引进花生专用根瘤菌剂进行应用试验,以验证其产品特性及对作物产量的影响。试验结果表明:应用根瘤菌剂的花生产量高,效果较好,而且降低了生产成本,相对增加了经济效益。%Experiments were conducted on the application effect of rhizobium agent to verify the product characteristics and to explore its effect on peanut yield for the purpose of seeking to improve peanut harvest and promote farmers' income. The test results show that the application of Rhizobium agent generates peanut high yield and reduce the production cost, leading to the relative increase of economic benefits.

  6. Reduction in pathogen populations at grapevine wound sites is associated with the mechanism underlying the biological control of crown gall by rhizobium vitis strain ARK-1. (United States)

    Kawaguchi, Akira


    A nonpathogenic strain of Rhizobium (=Agrobacterium) vitis, ARK-1, limited the development of grapevine crown gall. A co-inoculation with ARK-1 and the tumorigenic strain VAT07-1 at a 1:1 cell ratio resulted in a higher population of ARK-1 than VAT07-1 in shoots without tumors, but a significantly lower population of ARK-1 than VAT07-1 in grapevine shoots with tumors. ARK-1 began to significantly suppress the VAT07-1 population 2 d after the inoculation. This result indicated that ARK-1 reduced the pathogen population at the wound site through biological control. Although ARK-1 produced a zone of inhibition against other tumorigenic Rhizobium spp. in in vitro assays, antibiosis depended on the culture medium. ARK-1 did not inhibit the growth of tumorigenic R. radiobacter strain AtC1 in the antibiosis assay, but suppressed the AtC1-induced formation of tumors on grapevine shoots, suggesting that antibiosis by ARK-1 may not be the main mechanism responsible for biological control.

  7. Studies on the Alfalfa Growing Effects of Alfalfa Rhizobium%苜蓿根瘤菌剂对紫花苜蓿生长影响研究

    Institute of Scientific and Technical Information of China (English)

    樊川; 杨旭升; 曹亚斌


    通过不同剂量苜蓿根瘤菌接种两种紫花苜蓿试验,比较了接种根瘤菌剂对紫花苜蓿生长的影响。试验结果表明:接种苜蓿根瘤菌剂能够提高紫花苜蓿结瘤数量和根瘤重,促进紫花苜蓿的生长发育,增加苜蓿草的产草量。在所试验的接种剂量中,以每 kg 苜蓿种子接种12mL 根瘤菌剂为最佳接种量。%This paper studied the alfalfa growing effects of alfalfa rhizobium by inoculated different amounts.The experimental results showed that inoculating rhizobium can raise the nodulating amount of alfalfa and the weight of nodulations,promoting the growth of alfalfas and augment the productions of alfalfas.Among the different inoculated amounts,the amount of 12ml is the best inoculated amount.


    Directory of Open Access Journals (Sweden)

    María Camila Quevedo Rubiano


    Full Text Available This article presents the results of the thesis carried out in the research group of Biotechnology Teaching in Colombia, with the aim of providing teachers of Biology of Instituto Pedagogico Nacional a booklet that can strengthen the teaching of biotechnology processes using Rhizobium sp reduction of chemical fertilizers and symbiosis with Phaseolus vulgaris.   The booklet contains a proposal of practical activities that enable teachers of this institution to use spaces like the farm, enabling to teach biotechnology related to agronomy. Therefore, for this project was considered two Biological and Pedagogical approaches, the first is within the analytical empirical paradigm in the process of microbiological characterization of Rhizobium and their Biofertilizing ability in beans; and the teaching approach within the design of a booklet that includes the findings of this study as a contribution to the reduction of chemical fertilizers school farm. In order to have a complete analysis of the work it was subjected to quantitative and qualitative methods.   This biotech practice is included in the booklet showing in bioassays that bacteria has biofertilizer without inhibiting potential symbiosis, and that research and teaching biological concepts from scientific expertise can be promoted in Biology class for students to understand its context in a significant way, to be used in different levels of education; also it is a teaching strategy.

  9. Ledelse i et interventionsperspektiv

    DEFF Research Database (Denmark)

    Keiding, Tina Bering


    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...

  10. Populisme et politique


    Ivekovic, Rada


    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...

  11. Essential Tremor (ET): Surgical Options (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 , and ...

  12. Et Murstenstårn

    DEFF Research Database (Denmark)

    Jensen, Thomas Bo


    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"....

  13. Des racines et des ailes

    Directory of Open Access Journals (Sweden)

    Stéphanie Vincent-Geslin


    Full Text Available Les mobilités pendulaires semblent être en augmentation en Europe depuis une dizaine d’années. Cette croissance du temps passé à se déplacer amène à remettre en question la conjecture de Zahavi et apparaît relativement inexplicable en regard du paradigme classique de l’acteur rationnel traditionnellement utilisé dans le champ des transports. Si, dans la littérature, les temps de déplacements sont principalement expliqués par le contexte résidentiel, la forme urbaine et le travail, ce cadre explicatif ne dit rien des processus de décision eux-mêmes qui amènent aux pendularités intensives.À partir d’une enquête qualitative menée auprès de pendulaires français, suisses et belges, cette contribution propose d’analyser les arbitrages et les éléments déterminants des processus de la grande pendularité. Les mobilités quotidiennes pendulaires apparaissent comme le résultat de compromis entre activité professionnelle, attachement résidentiel et choix de vie et prennent ainsi la forme de stratégies de conciliation entre vie privée et vie professionnelle. Ces mobilités spatiales permettent alors paradoxalement la préservation des ancrages résidentiels, sociaux et familiaux.Roots and wings. Long-distance commuting patterns, or how to conciliate professional and personal lifeLong-distance commuting patterns appear to be increasing in Europe over the last ten years. These raising mobility patterns lead to reappraise the Zahavi conjecture and appear largely inexplicable by the classical rational actor paradigm traditionally used in transportation research. In literature, commuting is mainly explained by residential contexts, urban forms and job. Nevertheless this theoretical frame says little about the decision-making processes themselves. Based on a qualitative survey conducted in three European countries - France, Belgium and Switzerland – among a population of high commuters, this paper proposes an analysis of

  14. Acta Aeronautica et Astronautica Sinica

    Institute of Scientific and Technical Information of China (English)


    @@@@ABSTRACTS Motion Estimation and Compensation Based on Trifocal Tensor and BMA.WANG Yang-li, WU Cheng-ke(School of Information Engineering, Xidian University, Xi′an 710071, China).Acta Aeronautica et Astronautica Sinica(ISSN 1000-6893),Vol.22,no.2,Mar.2001,P117-120. 10 Chinese. To overcome some drawbacks of the block matching algorithm (BMA), which can not accurately describe object rotation, camera panning and zooming, this paper introduces the trilinear constraint and trifocal-tensor-based pixel transfer used in computer vision for motion estimation and compensation. In this method, the trifocal tensor is first estimated by an algorithm based on projection matrix, corresponding relations between two of three images are then determined by BMA and represented with block-based motion vectors, and finally, motion estimation and compensation are carried out by trifocal transferring. As it is not accurate to approximate the dense correspondence between two of the three views by the above block-based motion vectors, using trifocal transferring only will not yield good compensation results. To solve this problem, the paper further puts forward a motion estimation method combining trifocal transferring with BMA. Experiments have been carried out on video sequences to compare the performance of this method with that of BMA, and the results show that this method is superior when there are scene depth variation and camera translation.

  15. Charles et ses images

    Directory of Open Access Journals (Sweden)

    Anne-Marie Baron


    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.

  16. Optimisation combinatoire Theorie et algorithmes

    CERN Document Server

    Korte, Bernhard; Fonlupt, Jean


    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

  17. Multiple ETS family proteins regulate PF4 gene expression by binding to the same ETS binding site.

    Directory of Open Access Journals (Sweden)

    Yoshiaki Okada

    Full Text Available In previous studies on the mechanism underlying megakaryocyte-specific gene expression, several ETS motifs were found in each megakaryocyte-specific gene promoter. Although these studies suggested that several ETS family proteins regulate megakaryocyte-specific gene expression, only a few ETS family proteins have been identified. Platelet factor 4 (PF4 is a megakaryocyte-specific gene and its promoter includes multiple ETS motifs. We had previously shown that ETS-1 binds to an ETS motif in the PF4 promoter. However, the functions of the other ETS motifs are still unclear. The goal of this study was to investigate a novel functional ETS motif in the PF4 promoter and identify proteins binding to the motif. In electrophoretic mobility shift assays and a chromatin immunoprecipitation assay, FLI-1, ELF-1, and GABP bound to the -51 ETS site. Expression of FLI-1, ELF-1, and GABP activated the PF4 promoter in HepG2 cells. Mutation of a -51 ETS site attenuated FLI-1-, ELF-1-, and GABP-mediated transactivation of the promoter. siRNA analysis demonstrated that FLI-1, ELF-1, and GABP regulate PF4 gene expression in HEL cells. Among these three proteins, only FLI-1 synergistically activated the promoter with GATA-1. In addition, only FLI-1 expression was increased during megakaryocytic differentiation. Finally, the importance of the -51 ETS site for the activation of the PF4 promoter during physiological megakaryocytic differentiation was confirmed by a novel reporter gene assay using in vitro ES cell differentiation system. Together, these data suggest that FLI-1, ELF-1, and GABP regulate PF4 gene expression through the -51 ETS site in megakaryocytes and implicate the differentiation stage-specific regulation of PF4 gene expression by multiple ETS factors.

  18. Poliovirus et Apoptose



    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...

  19. Fait migratoire et genre


    Zaidman, Claude


    « 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...

  20. Genre, raison et nation

    Directory of Open Access Journals (Sweden)

    Rada Ivekovic


    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.

  1. Hyalinosis cutis et mucosae. (United States)

    Vago, Bernadette; Hausser, Ingrid; Hennies, Hans Christian; Enk, Alexander; Jappe, Uta


    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.

  2. Fiction et typification.

    Directory of Open Access Journals (Sweden)

    Nathalie Zaccaï-Reyners


    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.

  3. Identification and sequence analysis of the Rhizobium meliloti dctA gene encoding the C4-dicarboxylate carrier. (United States)

    Engelke, T; Jording, D; Kapp, D; Pühler, A


    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 transport and in nitrogen fixation. These mutants were mutated in regulatory dct genes which do not play an essential role in the symbiotic state. Thin sections of alfalfa nodules induced by the wild type and class I and class II mutants were analyzed by light microscopy. Class mutants induced typical Fix- nodules, showing a large senescent zone, whereas nodules induced by class II mutants only differed in an enhanced content of starch granules compared with wild-type nodules. Class I mutants could be complemented by a 2.1-kilobase SalI-HindIII subfragment of cosmid pRmSC121. DNA sequencing of this fragment resulted in the identification of an open reading frame, which was designated dctA because Tn5 insertion sites of the class I mutants mapped within this coding region. The dctA gene was preceded by a nif consensus promoter and an upstream NifA-binding element. Upstream of the dctA promoter, the 5' end of the R. meliloti dctB gene could be localized. The amino acid sequence of the N-terminal part of the R. meliloti DctB protein shared 49% homology with the corresponding part of the R. leguminosarum DctB protein. The DctA protein consisted of 441 or 453 amino acids due to two possible ATG start codons, with calculated molecular masses of 46.1 and 47.6 kilodaltons, respectively. The hydrophobicity plot suggests that DctA is a membrane protein with several membrane passages. The amino acid sequences of the R. meliloti and the R. leguminosarum DctA proteins were highly conserved (82%).

  4. SEÑALES PRODUCIDAS POR Rhizobium leguminosarum EN LA INTERACCIÓN CON FRIJOL COMÚN (Phaseolus vulgaris L.

    Directory of Open Access Journals (Sweden)

    María C. Nápoles García


    Full Text Available La interacción Rhizobium-leguminosas depende de un complejo intercambio de señales, que se mantiene durante todo el proceso simbiótico y de las que solamente una combinación correcta permitirá una simbiosis eficiente. Estas plantas secretan flavonoides, reconocidos por bacterias compatibles y que inducen sus genes nod. Estos codifican las proteínas que sintetizan y exportan lipoquitooligosacáridos conocidos como factores Nod. Los factores Nod activan los procesos de infección e inician la división celular en la raíz, hasta la formación del nódulo y participan también en la fijación biológica del nitrógeno. Existen evidencias de que el uso de inductores de los genes nod incrementa la nodulación en algunas leguminosas. El objetivo de este trabajo fue estudiar la producción de algunas moléculas señales, inducidas por la isoflavona genisteína en una cepa de R. leguminosarum y evaluar el impacto de esa inducción en el efecto del inóculo sobre plantas de frijol común. La fracción lipídica en los inóculos fue extraída con n-butanol y analizada por cromatografía de capa fina, cromatografía líquida de alta resolución y cromatografía gaseosa acoplada a un espectrómetro de masas. En los inóculos inducidos con genisteína se detectó una cantidad superior de lipooligosacáridos (factores de nodulación y de ácidos grasos de alto peso molecular, con diferencias significativas respecto a los controles sin inducir. En relación con ese enriquecimiento en moléculas señales, los inóculos inducidos con genisteína, mostraron un efecto positivo en las plantas de frijol de la variedad Cubacueto 25-9, con mayor número de nódulos y contenido de clorofila que las plantas no inoculadas (control.

  5. Bouvard et Pécuchet et le désir amoureux

    Directory of Open Access Journals (Sweden)

    Anne Herschberg Pierrot


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

  6. Dagens tilbud: Et pust til cv’et

    DEFF Research Database (Denmark)

    Meyer, Gitte


    ’Dear dr. Gitte Meyer’ lød indledningen forleden på det, der viste sig at være en art akademisk Nigeria-brev. Det var da underholdende. Men mailen er også et udtryk for, at hele publiceringscirkusset trænger til et eftersyn.......’Dear dr. Gitte Meyer’ lød indledningen forleden på det, der viste sig at være en art akademisk Nigeria-brev. Det var da underholdende. Men mailen er også et udtryk for, at hele publiceringscirkusset trænger til et eftersyn....

  7. Imagination et incarnation

    Directory of Open Access Journals (Sweden)

    Nicolas de Warren


    Full Text Available Il n’est pas inhabituel de considérer l’imagination comme une conscience d’objets non réels, ayant la forme d’images internes ou de représentations privées de toute incarnation spatiale. Dans cet article j’interroge la phénoménologie de l’imagination de Husserl à partir de deux questions : l’imagination est-elle un type de conscience d’image ? L’imagination, est-elle privée de toute incarnation spatiale ? Après avoir reconstruit la distinction nette opérée par Husserl entre imagination et conscience d’image (l’imaginaire n’est pas une image mentale interne, j’explore la thèse de Husserl, fort suggestive, selon laquelle toute imagination implique la projection du corps vécu. Loin d’être entièrement dépourvu de spatialité, l’imaginaire exhibe des caractéristiques quasi-spatiales, et il est fondé sur ce qui est « le plus propre » de mon corps vécu – cela même que, pour ainsi dire, j’amène toujours avec moi, même dans les envols les plus éloignés de mon imagination.It is not uncommon to consider the imagination as a consciousness of non-real objects in the form of internal images or representations that are bereft of spatial incarnation. In this paper, I develop Husserl's phenomenology of the imagination along two questions: Is the imagination a type of image-consciousness? Is the imagination entirely bereft of spatial incarnation? After reconstructing Husserl's trenchant decoupling of the imagination from image-consciousness  (the imaginary is not an internal mental image, I explore Husserl's suggestive thesis that the imagination involves the projection of the lived-body. Rather than consider the imaginary as entirely bereft of spatiality, the imaginary exhibits quasi-spatial characteristics, and is grounded in the "ownmost" of my lived-body, which, as it were, I always take with me, even to the farthest reaches of my imagination.

  8. ET come home

    DEFF Research Database (Denmark)

    Fisher, J. B.; Whittaker, R. J.; Malhi, Y.


    of the analyses to variation in the performance of different metrics of potential evapotranspiration. Location Analyses are based on: (1) a latitudinal transect of sites (FLUXNET) for 11 different land-cover types; and (2) globally gridded data. Methods First, we review the fundamental concepts......–Monteith) model – for 11 different land-cover types. Finally, we compare these models at continental and global scales. Results At some sites the models differ by less than 7%, but generally the difference was greater than 25% across most sites. The temperature-based model estimated 20–30% less than the radiation...

  9. Burlesque et pyrotechnie


    Le Forestier, Laurent


    Dans un court article écrit en 1924, Buster Keaton s'est essayé à une fantaisiste « histoire des films comiques », qui aurait débuté par « l'âge de l'explosion », avant de se poursuivre avec « l'âge du fromage blanc », « l'âge du policeman », « l'âge de l'automobile », « l'âge du costume de bain » et, enfin, « l'âge actuel ». Cette histoire commence avant la Première Guerre mondiale : évoquant « l'âge du fromage blanc », Keaton note avec ironie que le lancer de tartes à la crème a formé « d'e...

  10. 多氯联苯污染土壤的紫云英-根瘤菌联合修复效应%Combined Remediation Effects of Astragalus sinicus L.Inoculated with Rhizobium huakuii on PCBs Contaminated Soils

    Institute of Scientific and Technical Information of China (English)

    李秀芬; 滕应; 骆永明; 李振高; 潘澄; 张满云; 宋静


    选用紫云英(Astragalus sinicus L.)作为宿主植物,通过盆栽试验研究了接种紫云英根瘤菌(Rhizobium huakuii)对多氯联苯污染土壤的修复效应.结果表明,经过100天的修复作用后,单接种根瘤菌、种植紫云英以及紫云英接种根瘤菌处理土壤中多氯联苯的去除率分别为20.5%、23.0%、53.1%,均显著高于对照处理(P<0.01).而且发现接种根瘤菌显著增加了紫云英根际土壤的微生物生物量碳、氮,明显增强了土壤微生物群落的碳源利用能力,从而改善了微生物群落功能多样性.可见,紫云英-根瘤菌共生体对多氯联苯污染土壤表现出较好的修复潜力.%The combined remediation effects of host plant {Astragalus sinicus L.) inoculated with rhizobium Rhizobium huakuii on PCBs contaminated soils was studied using pot experiments. The results showed that soil PCBs concentrations of single incubation of Rhizobium huakuii (R) and single planting Astragalus sinicus L. (P) decreased by 20.5% and 23.0%, respectively. Astragalus sinicus L. with incubation of Rhizobium huakuii had a clear role in PCBs removal in soils, PCBs concentration in polluted soils decreased by 53.1%, all of which were significantly higher than the untreated soils (P<0.01). We also observed that soil microbial communities in Astragalus sinicus L. rhizosphere soils had a higher microbial biomass C and N and carbon utilization rate, improving the functional diversity of the soil microbial community. The results suggested the great potential of planting Astragalus sinicus L. with incubation of Rhizobium huakuii in remediation of PCBs contaminated soils.

  11. Immobilization and Survival of Root Nodule Bacterium Rhizobium leguminosarum Biovar viciae / Gumiņbaktērijas Rhizobium leguminosarum biovar viciae imobilizācija un dzīvotspēja

    Directory of Open Access Journals (Sweden)

    Žvagiņa Signe


    Full Text Available Rhizobium leguminosarum biovar viciae ir augsnes baktērija, kas spēj veidot gumiņus uz zirņu, pupu, lēcu un vīķu saknēm un saistīt atmosfēras slāpekli simbiozē ar augiem. Gumiņbaktērijas izmanto lauksaimniecībā kā bioloģiskus mēslošanas līdzekļus augu augšanas veicināšanai. Komerciālos gumiņbaktēriju preparātus var iegādāties sausā, šķidrā vai liofilizētā formā. Parasti izmanto sausos sagatavotos mēslošanas līdzekļus uz kūdras bāzes. Šī pētījuma mērķis bija imobilizēt R. leguminosarum un noteikt tās dzīvotspēju šķidrumā un dažādos nesējmateriālos, lai izstrādātu uzlabotus gumiņbaktēriju preparātus. Imobilizēšanai izmantoja piecus sterilizētus materiālus: kūdru, māla pulveri, divu veidu ovālus šūnainās keramikas agregātus un cilindriskas keramikas granulas, kas izgatavotas no Planču depozīta Devona perioda māla. Imobilizāciju veica 2,5 stundu laikā 20 °C temperatūrā. Vēlāk kūdru, pulveri un granulas noberza un sasmalcināja ūdenī ar sterilu piestiņu, lai atdalītu pielipušās baktērijas. Baktēriju kolonijas veidojošo vienību skaitu noteica, izsējot iegūto suspensiju atšķaidījumus Petri traukos ar agarizētu barotni. Dzīvotspēju noteica arī ar LIVE/DEAD epifluorescences metodi. Iegūtie rezultāti parādīja, ka nesējmateriāls ietekmē imobilizācijas sekmes un ka uzglabāšanas temperatūra ietekmē R. leguminosarum dzīvotspēju. Vislabākos rezultātus ieguva, uzglabājot baktērijas suspensijā vai imobilizējot uz kūdras. Rekomendējam uzglabāt R. leguminosarum produktus −18 °C vai 4 °C temperatūrā.

  12. Rhizobium rubi(T): a gram-negative phytopathogenic bacterium expressing the Lewis B epitope on the outer core of its lipooligosaccharide fraction. (United States)

    Gargiulo, Valentina; Garozzo, Domenico; Lanzetta, Rosa; Molinaro, Antonio; Sturiale, Luisa; De Castro, Cristina; Parrilli, Michelangelo


    The structure of the core oligosaccharide from the phytopathogenic bacterium Rhizobium rubi was deduced by combining information from complementary chemical approaches (alkaline and acid hydrolysis), similar to the "overlap peptide" strategy. This structure is new and it contains two main oligosaccharide backbones that differ in the substitution degree of the external Kdo unit. The relevant feature shared by both oligosaccharides is the presence of a tetrasaccharide motif that is similar to the blood group Lewis B antigen (Le(B)). This epitope differs from Le(B) in the glycosidic configuration of the glucosamine unit (alpha and not beta) and in the occurrence of acetyls substituents at O3 and/or O4 of the galactose moiety. Other notable structural features are the location of the Dha residue, the presence of a alpha-glucose unit that is linked to the inner Kdo unit, the high number of acid sugars and the highly branched core structure.

  13. Rhizobium radiobacter conjugation and callus-independent shoot regeneration used to introduce the cercosporin export gene cfp from Cercospora into sugar beet (Beta vulgaris L.). (United States)

    Kuykendall, L David; Stockett, Tammy M; Saunders, Joseph W


    Leaf spot disease caused by Cercospora is responsible for crop and profitability losses in sugar beet crops in the US and worldwide. The cfp gene that encodes a protein that exports phytotoxic cercosporins from Cercospora was conjugally transferred to sugar beet using Rhizobium radiobacter (Agrobacterium tumefaciens), to improve Cercospora-induced leafspot resistance. Conditions for shoot regeneration were optimized to increase regeneration/transformation efficiencies. Low-light and room-temperature conditions were favorable to sugar beet regeneration without callus when cytokinin had been added to the tissue culture medium. Using this procedure adventitious shoots from leaf pieces were obtained in a simple, one-step regeneration procedure. T7, a cfp-transgenic clone verified by PCR with gene-specific primers, is being propagated for leaf spot disease resistance evaluation.

  14. [Secretion of Phenolic Compounds into Root Exudates of Pea Seedlings upon Inoculation with Rhizobium leguminosarum bv. viceae or Pseudomonas siringae pv. Pisi]. (United States)

    Makarova, L E; Dudareva, L V; Petrova, I G; Vasil'eva, G G


    The content of apigenin, naringenin, pisatin, dibutyl-ortho-phthalate, and N-phenyl-2-naphthyl-amine were assayed in root exudates of pea (Pisum sativum L.) seedlings one day after their inoculation with Rhizobium leguminosarum, bv. viceae or Pseudomonas siringae pv. pisi, which represent, respectively, mutualistic and antagonistic strategies of interaction with a host plant. After inoculation with either bacteria, the concentrations of apigenin and pisatin in the root exudates were equal, whereas the concentrations of naringenin and N-phenyl-2-naphthylamine were different and those of dibutyl-o-phthalate were unchanged. A certain role is suggested for the phenolic compounds in an accomplishment of symbiotic relations of bacteria with a host plant.

  15. Co-inoculation with Rhizobium and plant growth promoting rhizobacteria (PGPR for inducing salinity tolerance in mung bean under field condition of semi arid climate

    Directory of Open Access Journals (Sweden)

    Muhammad Aamir


    Full Text Available Salinity stress severely affects the growth, nodulation and yield of mung bean (Vigna radiata L.. However, its growth can be improved under salinity stress by inoculation/co-inoculation with rhizobia and plant growth promoting rhizobacteria (PGPR containing 1-Aminocyclopropane-1-carboxylic acid (ACC deaminase enzyme. ACC-deaminase containing bacteria regulate the stress induced ethylene production by hydrolyzing the ACC (immediate precursor of ethylene into ammonia and ketobutyric acid, thus improve plant growth by lowering the ethylene level. A study was conducted under salt affected field conditions where pre-isolated strains of Rhizobium and PGPR were used alone as well as in combination for mitigating the salinity stress on growth, nodulation and yield of mung bean by following the randomized complete block design (RCBD. The data were recorded and analyzed statistically to see the difference among treatments.

  16. Le vieillard et le chevalier

    Directory of Open Access Journals (Sweden)

    Mélanie JECKER


    Full Text Available La fin du Moyen Âge fascine. Deux facteurs principaux expliquent l’attraction qu’exerce cette période : elle apparaît d’une part comme un moment historique riche car double, phase de transition entre le Moyen Âge et la Renaissance, où se mêlent des cadres de représentation anciens et nouveaux. L’insinuation d’une pensée humaniste balbutiante s’y traduirait notamment par l’émergence de la notion d’individu, qui constitue l’un des objets de ce travail. Il faut invoquer, d’autre part, l’image macabre d’un bas Moyen Âge hanté par l’idée de la maladie et de la mort depuis l’épidémie de peste noire de 1348, obsédé par la brièveté de la vie humaine. Ces deux facettes de « l’automne du Moyen Âge » tel que l’évoque avec poésie Joan Huizinga sont-elles autre chose qu’une plaisante image d’Epinal? Cette étude cherche précisément à déterminer le degré de validité de ces deux topiques, à travers l’analyse de la représentation des âges de la vie dans un corpus bien défini, celui de la biographie chevaleresque castillane du XVe siècle. L’intérêt porté à l’individu, la conscience de la singularité impliquent en effet celle du caractère mouvant de la personne, or quel thème mieux que celui des âges permet de confirmer ou d’infirmer l’hypothèse du surgissement d’une nouvelle manière de concevoir l’homme, proprement « renaissante », en ce siècle de transition , La nature même du corpus retenu – des récits biographiques – suggère en effet une mutation dans l’appréhension de la personne, une attention prêtée à sa progressive transformation. L’étude de la représentation de la vieillesse, en particulier, révèle non seulement à quel point était alors réelle cette prétendue obsession de la déchéance physique et de la mortalité, mais aussi dans quelle mesure étaient soulignés et valorisés les changements individuels parallèles à l

  17.  Final review of the Séralini et al. (2012a publication on a 2-year rodent feeding study with glyphosate formulations and GM maize NK603 as published online on 19 September 2012 in Food and Chemical Toxicology

    Directory of Open Access Journals (Sweden)

    European Food Safety Authority


    Full Text Available On 19 September 2012, Séralini et al. published online in the scientific journal Food and Chemical Toxicology a publication describing a 2-year feeding study in rats investigating the health effects of genetically modified maize NK603 with and without Roundup WeatherMAX® and Roundup® GT Plus alone (both are glyphosate-containing plant protection products. As requested by the European Commission, EFSA reviewed this publication taking into consideration assessments conducted by Member States and any clarification given by the authors. The assessments of Member States and EFSA revealed an overall agreement. The study as reported by Séralini et al. was found to be inadequately designed, analysed and reported. The authors of Séralini et al. provided a limited amount of relevant additional information in their answer to critics published in the journal Food and Chemical Toxicology. Taking into consideration Member States’ assessments and the authors’ answer to critics, EFSA reaches similar conclusions as in its first Statement (EFSA 2012. The study as described by Séralini et al. does not allow giving weight to their results and conclusions as published. Conclusions cannot be drawn on the difference in tumour incidence between treatment groups on the basis of the design, the analysis and the results as reported. Taking into consideration Member States’ assessments and the authors’ answer to critics, EFSA finds that the study as reported by Séralini et al. is of insufficient scientific quality for safety assessments. EFSA concludes that the currently available evidence does not impact on the ongoing re-evaluation of glyphosate and does not call for the reopening of the safety evaluations of maize NK603 and its related stacks. EFSA’s evaluation of the Séralini et al. article is in keeping with its role to review relevant scientific literature for risk assessment on an ongoing basis to ensure that the advice it provides is up-to-date.

  18. Single acquisition of protelomerase gave rise to speciation of a large and diverse clade within the Agrobacterium/Rhizobium supercluster characterized by the presence of a linear chromid. (United States)

    Ramírez-Bahena, Martha H; Vial, Ludovic; Lassalle, Florent; Diel, Benjamin; Chapulliot, David; Daubin, Vincent; Nesme, Xavier; Muller, Daniel


    Linear chromosomes are atypical in bacteria and likely a secondary trait derived from ancestral circular molecules. Within the Rhizobiaceae family, whose genome contains at least two chromosomes, a particularity of Agrobacterium fabrum (formerly A. tumefaciens) secondary chromosome (chromid) is to be linear and hairpin-ended thanks to the TelA protelomerase. Linear topology and telA distributions within this bacterial family was screened by pulse field gel electrophoresis and PCR. In A. rubi, A. larrymoorei, Rhizobium skierniewicense, A. viscosum, Agrobacterium sp. NCPPB 1650, and every genomospecies of the biovar 1/A. tumefaciens species complex (including R. pusense, A. radiobacter, A. fabrum, R. nepotum plus seven other unnamed genomospecies), linear chromid topologies were retrieved concomitantly with telA presence, whereas the remote species A. vitis, Allorhizobium undicola, Rhizobium rhizogenes and Ensifer meliloti harbored a circular chromid as well as no telA gene. Moreover, the telA phylogeny is congruent with that of recA used as a marker gene of the Agrobacterium phylogeny. Collectively, these findings strongly suggest that single acquisition of telA by an ancestor was the founding event of a large and diverse clade characterized by the presence of a linear chromid. This clade, characterized by unusual genome architecture, appears to be a relevant candidate to serve as a basis for a possible redefinition of the controversial Agrobacterium genus. In this respect, investigating telA in sequenced genomes allows to both ascertain the place of concerned strains into Agrobacterium spp. and their actual assignation to species/genomospecies in this genus.

  19. 16S rDNA analysis of Rhizobium fredii 15067 and Azotobacter chroococcum 10006%快生型大豆根瘤菌(Rhizobium fredii)15067与褐球固氮菌(Azotobacter chroococcum)10006的16S rDNA分析

    Institute of Scientific and Technical Information of China (English)

    李海英; 刘金玲; 张喜波; 康妮; 于海鹏; 李鹏


    分别对快生型大豆根瘤菌(Rhizobium fredii)15067和褐球固氮菌(Azotobacter chroococ-cum)10006两个菌株进行了16S rDNA的全序列测定,将此全序列与已知相关的16S rDNA进行了比较及聚类分析,得到系统发育树状图.在系统发育树中,根瘤菌15067隶属于中华根瘤菌属,与Sinorhizobium xinjiangense IAM 14142,SinoRhizobium fredii SjzZ 4构成一个分支,其中与S.fredii SjzZ4的相似性最高,达99.72%;固氮菌10006处于固氮菌属分支中,其中和Azotobacter chroococcum AM12A,Azotobacter chroococcum的相似性均高达99.93%.为确定两株菌株的分类地位、进一步发掘和利用菌株的优良性状提供了参考依据.

  20. Et håndtryk

    DEFF Research Database (Denmark)

    Eriksen, Karen Westphal; Schytz Juul, Mathilde


    Hør Karen Westphal Eriksen fortælle om udvalgte værker og temaer fra udstillingen "Et håndtryk". Udstillingen omhandler dansk-fransk avantgardekunst og er et samarbejde mellem Fyns Kunstmuseum og Statens Museum for Kunst. Udstillingen kan ses på Fyns Kunstmuseum frem til februar 2011...

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

    Directory of Open Access Journals (Sweden)

    Tambalo Dinah D


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

  2. Analyse de Langues et cultures - Les TIC, enseignement et apprentissage

    Directory of Open Access Journals (Sweden)

    Élisabeth Brodin


    Full Text Available 1. Introduction Cet ouvrage constitue les actes du colloque des IUFM (Institut Universitaire de Formation des Maîtres de décembre 2003, intitulé "Quelles nouvelles perspectives pour l'enseignement / apprentissage des langues et cultures ?" On peut déplorer a priori que le titre du livre, au demeurant ambitieux, et le sous-titre ne reprennent pas la question des nouvelles perspectives apportées par les Technologies de l'Information et de la Communication (TIC à l'enseignement des langues e...

  3. Réseaux et histoires

    Directory of Open Access Journals (Sweden)

    Harrison White


    Full Text Available Les réseaux sociaux ne sont pas constitués de « tuyaux » reliant des entités figées. Ils résultent des efforts de contrôle des identités pour faire face à l’incertitude radicale, aussi bien dans le monde social que dans le monde bio-physique. Ces efforts de contrôle produisent des histoires, dont dérivent les liens qui constituent les réseaux. Ainsi, une relation est interprétée à travers des histoires, non seulement par ceux qui y participent mais aussi par les observateurs. Les histoires s’enchevêtrent et forment des assemblages dans lesquels des régularités peuvent être observées, notamment trois façons de différencier les liens. La première façon consiste à spécifier un type de lien sur la base des formes de recouvrement observées entre des identités et des groupes. La deuxième façon distingue l’asymétrie et la symétrie dans les relations. Enfin, la troisième façon de différencier est fondée sur la force des liens. Les liens peuvent donc être de type multiplexe ou spécialisé, selon qu’ils associent différents registres ou non, les topologies de réseau pouvant être reconstruites à partir de ces différentes perspectives. Dans tous les cas, la notion de réseau qui émerge de cette approche est étroitement liée à de complexes formations narratives et peut servir aussi bien aux acteurs qu’aux observateurs pour rendre compte de la vie sociale.Networks and storiesSocial networks are not « pipes » connecting motionless entities. They are the result of control attempts by identities dealing with uncertainty, both in their social and bio-physical environments. These control attempts evoke stories from which links constituting networks are derived. A relation is thus interpreted through stories, not only by those who are embedded in them, but also by observers. Stories intermesh and yield assemblages in which regularities can be observed, notably three ways of distinguishing links. The

  4. The "missing" typical Rhizobium leguminosarum O antigen is attached to a fatty acylated glycerol in R. leguminosarum bv. trifolii 4S, a strain that also lacks the usual tetrasaccharide "core" component. (United States)

    Cedergren, R A; Wang, Y; Hollingsworth, R I


    Rhizobium leguminosarum bv. trifolii 4S has a lipopolysaccharide O antigen that lacks galactose and many of the typical glycosyl components found in related strains. Here, we show that it also lacks the typical core tetrasaccharide but synthesizes an alternative glycolipid that contains galactose and the typical O-antigen glycosyl components, suggesting that in this strain, the O antigen is transferred to an alternative lipid acceptor.

  5. Effect of Nitrogen and Rhizobium Interaction on Growth, Nodule Development and Yield in Soybean%氮和根瘤菌交互作用对大豆生长、结瘤及产量的影响

    Institute of Scientific and Technical Information of China (English)

    程鹏; 王金生; 刘丽君; 年海; 林蔚刚; 王红蕾; 吴俊江


      采用根瘤菌拌种,以氮素及根瘤菌为试验因素设置处理,随机区组设计,研究了氮和根瘤菌交互作用对大豆根瘤生长及大豆产量和品质的影响。结果表明,接入的根瘤菌能有效的增加大豆植株的结瘤数量,而施入大量的氮肥则产生抑制作用。根瘤菌的接入对大豆R3期生物量的积累产生一定的促进作用。在接入根瘤菌的条件下,施入氮肥单个根瘤体积增大;不施入氮肥,单个根瘤体积变小。产量构成因子综合作用的结果使得接种根瘤菌与施入氮肥相比,更能提高大豆的产量。%The interactive effects of rhizobium inoculation and nitrogen application on nodule development, yield and quality of soybean were studied with randomized complete block design. Results showed that the number of root nodules was increased significantly by rhizobium inoculation, but was inhibited under high lev⁃el of nitrogen. Significant improvement of plant biomass accumulation by inoculation rhizobium was found at R3 stage. Under inoculation conditions, the single root volume was increased with nitrogen treatment, but reduced without nitrogen. The interactive effects of yield components showed that the improvement of soybean yield was more significant with rhizobium inoculation than nitrogen treatment.

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

    Energy Technology Data Exchange (ETDEWEB)

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


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

  7. 大豆新品种山宁17根瘤菌剂与氮肥配施技术研究%Study on Combined Application Technique of Rhizobium Inoculant and Nitrogen Fertilizer for New Soybean Variety Shanning 17

    Institute of Scientific and Technical Information of China (English)

    李继存; 赵云; 杨旭; 周静; 付贵阳; 赵恩海; 李素真


    通过小区试验对山宁17大豆新品种的根瘤菌拌种与施肥技术进行了研究。结果表明,接种根瘤菌与氮肥追施可获得较高产量,且在接种根瘤菌及磷钾肥相同的情况下,每666.7m2花期追施尿素3.75 kg的大豆产量最高,比对照(666.7m2基施尿素5 kg)增产5.33%,并优于等量缓释氮肥基施的效果。%The techniques of dressing seeds with rhizobium and fertilization for new soybean variety Shanning 17 were studied by plot experiment .The results showed that inoculating rhizobium and topdressing nitrogen fertilizer contributed to obtaining higher yield .Under the conditions of inoculating rhizobium and fer-tilizing with the same phosphorus and potassium fertilizers , topdressing 3.75 kg nitrogen fertilizer per 666.7m2 at flowering stage had the highest soybean yield , which increased by 5.33% compared with that of control (basal applying 5 kg nitrogen fertilizer per 666.7m2),and was higher than that of basal applying same amount of slow release nitrogen fertilizer .

  8. AMF和饭豆根瘤菌对饭豆、玉米套种促生作用的研究%Effects of AMF and Rhizobium co-inoculation on alternative plantation of rice bean and corn

    Institute of Scientific and Technical Information of China (English)

    周小宇; 郑慧芬; 潘峰; 何绍江; 胡正嘉; 冯新梅


    将从饭豆根瘤中分离的饭豆根瘤菌(Rhizobium sp.CYY3302,Rhizobium sp.HCY9101,Rhizobium SP.JMC1C1402)与AMF(Arbuscular Mycorrhizal Fungi)共同接种于饭豆,进行饭豆、玉米田间小区套种试验.结果表明,接种饭豆根瘤菌和AMF的处理与未接种的处理相比,饭豆的结瘤率比对照提高52%~134%;饭豆及玉米的菌根感染率比对照分别增加43.1%~80%和46.8%~97.6%;饭豆的产量提高了54%~67%,而玉米的产量提高了2.4%~19.5%.研究结果还表明:豆科作物接种根瘤菌,即使在种过豆科作物的老区,也是有效的.

  9. 接种耐酸根瘤菌对紫花苜蓿生长的影响%Effect of Acid-tolerant Rhizobium on the Growth of Alfalfa

    Institute of Scientific and Technical Information of China (English)

    张媚佳; 徐淑韵; 徐苏凌; 方勇; 徐根娣


    The seeding of alfalfa on the acid soil with acid-tolerant rhizobium is to investigate the effects on the growth of alfalfa, and provide a theoretical and technical basis for the cultivation of alfalfa to the south. The results show that acid-tolerant rhizobium inoculation has promoted the growth of the 2 tested alfalfas, and there is breed difference of alfalfa when establishing symbiosis relationship with rhizobium.%为给南方紫花苜蓿的种植提供一定的理论和技术依据,采用土培法在酸性土壤上接种耐酸根瘤茵以探讨其对紫花苜蓿生长情况的影响.结果表明,接种耐酸根瘤菌对参试的2种紫花苜蓿生长都有促进作用,且紫花苜蓿在与根瘤菌建立共生关系时存在品种差异.

  10. Investing EU ETS auction revenues into energy savings

    Energy Technology Data Exchange (ETDEWEB)

    Sijm, J.P.M.; Boonekamp, P.G.M. [ECN Policy Studies, Petten (Netherlands); Summerton, P.; Pollitt, H.; Billington, S. [Cambridge Econometrics CE, Cambridge (United Kingdom)


    The overall objective of this study is to analyse the effects of using EU ETS auction revenues to stimulate investments in energy savings in three key target sectors, i.e. Households, Tertiary and Industry (including both ETS and non-ETS industrial installations). The scenarios used refer basically to the situation before the recent agreement on the Energy Efficiency Directive (EED) and include (a mixture of) different policy options to enhance energy savings in the target sectors, in particular (1) reducing the ETS cap, (2) introducing an Energy Efficiency Obligation (EEO) for energy suppliers or distributors, and/or (3) using ETS auction revenues to support additional (private) investments in raising energy efficiency. In order to meet this objective a variety of different policy scenarios have been defined and analysed by means of the 'Energy-Environment-Economy Model for Europe (E3ME)'. The study presents and discusses a large variety of scenario modelling results by the year 2020 at the EU27 level. These results refer to, among others, energy savings, GHG emissions, the ETS carbon price, household electricity bills and to changes in some macro- or socio-economic outcomes such as GDP, inflation, employment or international trade. Finally, the study discusses some policy findings and implications, including options to enhance the effectiveness of some EE policies, in particular those having a potential adverse effect on the ETS carbon price.

  11. Nietzsche, Darwin et le darwinisme


    Merlio, Gilbert


    Le darwinisme a été pour Nietzsche un auxiliaire précieux dans son combat contre le dualisme platonicien et chrétien. Nietzsche adhère aux deux idées qui le fondent : l’idée de lutte pour la vie et l’idée d’évolution. On ne peut comprendre l’homme en faisant abstraction de son origine animale, de ses instincts et de ses affects. La généalogie a pour tâche de les mettre au jour. Nietzsche critique cependant l’aspect mécanique et utilitaire de la sélection naturelle darwinienne qui n’envisage q...

  12. Voyage en train et paysage


    Bowie, Karen; Thom, René


    Karen Bowie a choisi le texte de cette communication du mathématicien et philosophe René Thom (1923-2002), prononcée lors du colloque « Arts et chemins de fer », 3e colloque de l’AHICF réuni en novembre 1993 dont les actes ont été publiés par la Revue d’histoire des chemins de fer 10-11 (1994), pour sa valeur de référence et d’actualité dans notre analyse des paysages créés par le chemin de fer. On voit ici que le paysage dessiné par l’infrastructure ferroviaire et celui créé par la vision du...

  13. Vi mangler endnu et panel

    DEFF Research Database (Denmark)

    Ritter, Thomas


    Vi mangler højtuddannede værdiskabere, som transformerer gode idéer og teknologier til indtjening og velstand. Først i mødet med markedet afgøres fremtiden. Troels Lund Poulsen bør nedsætte et kommercialiseringspanel, der byder ind med løsninger, hvordan Danmark bliver et land ikke kun med gode i...

  14. Porokeratosis palmaris et plantaris disseminata

    Directory of Open Access Journals (Sweden)

    Kaur Vineet


    Full Text Available A 30-year-old woman had porokeratosis palmaris et plantaris disseminata with unusual features. These included the sex of the patient, absence of family history of similar disease, onset of lesions on the shins and a significant furrow. There was also associated diabetes mellitus. It is suggested that porokeratosis palmaris et plantaris disseminata falls in the middle of the spectrum of porokeratoses.

  15. Et forslag til religionsneutral begravelsesplads

    DEFF Research Database (Denmark)

    Tvedt, Tilde; Lund, Signe


    Flere og flere mennesker ønsker sig et alternativ til den traditionelle kristne kirkegård. Enten fordi de ikke er religiøse, eller fordi de tilhører andre religioner. Et speciale på Københavns Universitet ser på, hvordan de nye behov kan imødekommes med en religionsneutral begravelsesplads i tæt...

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

    Directory of Open Access Journals (Sweden)

    Amalia Baraibar


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

  17. Effect of Rhizobium sp.W33 on copper accumulation and organic exudations of different plants grown on copper-contaminated soil%Rhizobium sp.W33对不同植物吸收铜和根际分泌物的影响

    Institute of Scientific and Technical Information of China (English)

    陈生涛; 何琳燕; 李娅; 袁彤彤; 盛下放; 黄智


    通过盆栽试验,采用1株植物促生细菌Rhizobium sp.W33接种黑麦草、狼尾草、高羊茅、紫花苜蓿、猪屎豆、油菜和印度芥菜等7种不同植物,考察了Cu胁迫下菌株对植物生物量、Cu含量和根际土壤中分泌物的影响,并筛选根瘤菌-植物联合修复重金属污染土壤的组合体系,以期初步探明细菌-植物联合修复重金属污染土壤的机制.结果表明,接种Rhizobium sp.W33后,有5种植物的干重增加了11%~56%,增加幅度为印度芥菜>黑麦草>高羊茅>狼尾草>油菜,紫花苜蓿和猪屎豆的干重下降.黑麦草、狼尾草、高羊茅和猪屎豆根内Cu含量接近或超过1000mg· kg-1,Cu大量积累在植物根部.Rhizobium sp.W33能够显著促进黑麦草吸收Cu(p<0.05),并提高其对Cu的富集系数和转移系数,增加根部和地上部的Cu总量.苹果酸是供试植物-细菌联合修复Cu污染土壤的主要有机酸种类,接种根瘤菌W33后黑麦草、狼尾草根际的苹果酸和水溶性糖含量降低,过氧化氢酶活性增加,其中,苹果酸、水溶性糖含量与黑麦草中Cu含量呈显著相关性(p<0.05).因此,根瘤菌W33-黑麦草联合体系修复重金属Cu污染土壤的效果最好,具有应用于重金属Cu污染土壤稳定修复的潜力.



    Šabršula, Jan


    NEWS: ROSTISLAV KOCOUREK, ESSAIS DE LINGUISTIQUE FRANÇAISE ET ANGLAISE. MOTS ET TERMES, SENS ET TEXTES. Essays in French and English Linguistics. Words and Terms, Meanings and Texts. Louvain – Paris – Sterling, Virginia; Editions Peeters, 2001, 441 pages.

  19. Produção de mudas de acácia colonizadas com micorrizas e rizóbio em diferentes recipientes Production of acacia plants colonized with mycorrhizas and rhizobium in different recipients

    Directory of Open Access Journals (Sweden)

    Jolimar Antonio Schiavo


    Full Text Available Realizou-se um experimento em casa de vegetação, com o objetivo de avaliar diferentes métodos na produção de mudas de Acacia mangium Willd, colonizadas com fungos micorrízicos arbusculares (FMAs e rizóbio. O delineamento experimental foi o inteiramente casualizado num esquema fatorial 4x2 (controle, FMAs, rizóbio e FMAs + rizóbio x blocos prensados e tubetes de plástico, com seis repetições. Os blocos prensados foram confeccionados com substratos orgânicos (bagaço de cana + torta de filtro de usina açucareira e vermiculita, colocados em fôrma metálica de 60x40x20 cm e prensados a 10 kgf cm-2, a fim de proporcionar agregação do material. A inoculação do rizóbio foi realizada com estirpe selecionada para a espécie (Br 3609, Br 6009. A inoculação de FMAs foi feita no momento da confecção dos blocos. Mudas de Acacia mangium que receberam inóculo de FMAs + rizóbio e produzidas em blocos prensados apresentaram maior produção de matéria seca e conteúdo de N na parte aérea. O conteúdo de P na parte aérea é significativamente maior somente nas mudas infectadas com os FMAs, independentemente do tipo de recipiente.A greenhouse experiment was carried out in order to evaluate different methods to produce Acacia mangium Willd plant seedlings, inoculated with arbuscular mycorrhizal fungi (AMF and rhizobium. A completely randomized design in a factorial scheme 4x2 (control, AMF, rhizobium and AMF + rhizobium x pressed blocks and plastic tubes, with six repetitions was used. The pressed blocks used to produce Acacia mangium plants were made with organic residue from sugarcane (sugarcane bagasse + filter cake and vermiculite. The inoculation with rhizobium was done with selected strain (Br 3609, Br 6009. The inoculation with AMF was done at the time when pressed blocks were made. Acacia mangium plants inoculated with both AMF + rhizobium led to a significant increase in dry matter yield and N content of shoot plants, only in

  20. ETS-5, ETS-6, and COMETS projects in Japan (United States)

    Iida, Takashi; Wakana, Hiromitsu; Obara, Noriaki


    Three satellite communication projects now in progress in Japan are described. The first is a project to establish a telecommunication network for tele-education, TV conference, and tele-medicine in the Asia-Pacific region by using the Japan's Engineering Test Satellite-5 (ETS-5). The second is a project of the ETS-6 satellite, to be launched in 1993, for inter-satellite communication, mobile and fixed communication, and millimeter wave personal communication experiments. The third is a project of the Communications and Broadcasting Engineering Test Satellite (COMETS), to be launched in 1997, for advanced mobile satellite communication, inter-satellite link, and advanced broadcasting experiments at higher frequencies.

  1. 一株产聚羟基脂肪酸酯根瘤菌Rhizobium sp.H2-5的筛选与鉴定%Screening and Identification of a Polyhydroxyalkanoate Producing Strain Rhizobium sp. H2-5

    Institute of Scientific and Technical Information of China (English)

    杨姗姗; 张红蕊; 伏圣秘; 刘新利; 陈静


    聚羟基脂肪酸酯(Polyhydroxyalkanoates,PHAs)是微生物产生的胞内能量和碳源储藏性物质,因其可以作为生物塑料具有完全可生物降解性而倍受关注.本研究从自然界中取样,经过富集培养、尼罗蓝荧光显色、苏丹黑染色、提取发酵产物红外光谱和元素分析等,筛选到一株聚羟基脂肪酸酯产生菌.通过形态观察、生理生化试验以及16S rDNA分子鉴定,确定该菌为根瘤菌Rhizobium sp.H2-5.图4参20

  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

    Directory of Open Access Journals (Sweden)

    Patrícia P. Pinto


    Full Text Available High temperatures can affect the survival, establishment and symbiotic properties of Rhizobium strains. Bean nodulating Rhizobium strains are considered particularly sensitive because on this strains genetic recombinations and/or deletions occur frequently, thus compromising the use of these bacteria as inoculants. In this study R. tropici and R. leguminosarum bv. phaseoli strains isolated from Cerrado soils were exposed to thermal stress and the strains’ growth, survival and symbiotic relationships as well as alterations in their genotypic and phenotypic characteristics were analyzed. After successive thermal shocks at 45ºC for four hours, survival capacity appeared to be strain-specific, independent of thermo-tolerance and was more apparent in R. tropici strains. Certain R. leguminosarum bv. phaseoli strains had significant alterations in plant dry weight and DNA patterns obtained by AP-PCR method. R. tropici strains (with the exception of FJ2.21 were more stable than R. leguminosarum bv. phaseoli strains because no significant phenotypic alterations were observed following thermal treatments and they maintained their original genotypic pattern after inoculation in plants.Altas temperaturas podem afetar a sobrevivência, estabelecimento e as propriedades simbióticas em estirpes de Rhizobium. As estirpes capazes de nodular o feijoeiro têm sido consideradas particularmente sensíveis, porque nessas estirpes é comum a ocorrência de recombinações e/ou deleções genômicas comprometendo, muitas vezes, a sua utilização como inoculantes. Neste trabalho, procurou-se avaliar a capacidade de crescimento e sobrevivência em temperaturas elevadas de estirpes de Rhizobium efetivas na fixação de nitrogênio no feijoeiro isoladas dos cerrados, bem como avaliar suas características fenotípicas e genotípicas após choque térmico. A capacidade de sobrevivência à temperaturas elevadas, avaliada após choques térmicos sucessivos (45ºC por 4

  3. 小分子Rhizobium sp.N613胞外多糖的羧甲基化及其抗肿瘤活性%Carboxymethylation and antitumor activity of low molecular weight exopolysaccharide from Rhizobium sp.N613

    Institute of Scientific and Technical Information of China (English)

    聂瑞红; 吕利华; 魏国琴; 王桂琴; 赵良启


    Objective To establish a preparation technology of carboxymethylated low molecular weight exopolysaccharide from Rhizobium sp. N613 ( CM-LREPS ) and to explore its antitumor activity. Methods Low molecular weight exopolysaccharide from Rhizobium sp. N613 ( LREPS ) was modified by CICH2COOH using ethanol as the solvent. The reaction conditions were optimized by orthogonal test and a series of CM-LREPS were acquired. The molecular structure of the CM-LREPS was analyzed by fourier transform infrared spectra( IR ). Then the antitumor activities of four different degrees of substitution were evaluated in mice bearing hepatoma ascites H22. Results The IR results indicated that LREPS was carboxymethylated successfully. Antitumor test indicated that the inhibition rate reached 59. 2% when the degree of substitution of CM-LREPS was 0. 659. Using the degree of substitution and the inhibition rate as detection indicators, the optimum preparation conditions of CM-LREPS were as follows: the concentration of ethanol of 90%, 2. 0 g LREPS, 3. 0 g CICH2, COOH ,4. 0 g NaOH, the etherification temperature of 40℃ and the reaction time of 4 h. Conclusion The technology of preparing CM-LREPS is successfully established. Moreover,the relevant technical parameters are obtained, which lay a certain foundation for the production and application of the polysaccharide.%目的 建立小分子Rhizobium sp.N613胞外多糖羧甲基化的制备工艺并研究其抗肿瘤活性.方法 以乙醇为溶剂,用一氯乙酸对小分子Rhizobium sp.N613胞外多糖 (LREPS) 进行羧甲基化修饰,通过正交试验考察了乙醇体积分数、一氯乙酸用量、氢氧化钠用量、醚化温度及时间对羧甲基化LREPS (CM-LREPS) 羧甲基取代度 (DS) 的影响,并获得一系列CM-LREPS产物.红外图谱表征CM-LREPS分子结构.选取4组取代度(0.285,0.531,0.659和0.899)的CM-LREPS样品进行了小鼠肝癌腹水瘤H22抑瘤效果检验.结果 红外图谱分析表明,实现了LREPS

  4. Rejets et environnement du CERN

    CERN Document Server

    Vojtyla, P


    La radioactivité de l’environnement autour de l’Organisation Européenne pour la Recherche Nucléaire (CERN) et les doses de rayonnements qui en résultent pour la population avoisinante sont contrôlées par la Commission de Sécurité du CERN et de manière indépendante par les autorités compétentes des deux États Hôtes, l’Institut de Radioprotection et de Sûreté Nucléaire (IRSN) côté France et l’Office Fédéral de la Santé Publique (OFSP) côté Suisse (voire Chapitre 8.6). Dans ce rapport, les résultats de mesures concernent en particulier le territoire suisse. L’ensemble des mesures effectuées en 2006 prouve que le fonctionnement des installations du CERN était sans conséquence radiologique sur l’environnement et la population. Le contrôle des émissions montre que les rejets effectifs se situent, également en 2006, nettement en dessous des limites réglementaires. Ce constat est confirmé par le contrôle des immissions dans l’environnement. Le CERN a bien respecté en 2...

  5. Plafonds froids et introduction d'air laminaire

    CERN Document Server

    Pepinster, P


    Dès le milieu des années 1980, on a pu observer une tendance à l'augmentation des charges thermiques internes dans les bâtiments administratifs, principalement due à l'arrivée de l'informatique et de la bureautique. Cet accroissement de charges a finalement atteint un record de 100 W/m2 fin des années 80 pour se stabiliser en règle générale entre 50 et 70 W/m2. Traditionnellement, c'est le renouvellement d'air refroidi et insufflé dans les locaux qui combat les apports calorifiques, et le débit d'air pulsé est proportionnel aux charges à évacuer. Cette augmentation des charges a donc généré des vitesses de circulation d'air résiduelles insatisfaisantes pour le confort des occupants, et les ingénieurs en climatisation ont dû revoir la technologie appliquée jusqu'alors. Ce document présente les techniques actuelles qui permettent de satisfaire à l'exigence d'absence de courant d'air aux places de travail, et ainsi assurer le bien-être humain dans le domaine climatique.

  6. Chapitre VI. Saints et sanctuaires



    L’islam se présente comme une religion monothéiste qui n’admet aucun intermédiaire entre Dieu et les hommes, ni aucun associé à Dieu. Le Prophète lui-même, bien que proche d’Allah, est un simple mortel : « Ainsi, même le Prophète, celui de tous les hommes qui se rapproche le plus de Dieu, quand nous l’interrogeons sur ses facultés surnaturelles, se trouve beaucoup plus éloigné du domaine de la divinité que ne le sont les prophètes et les législateurs dans les autres religions. Et il ne faut p...

  7. Dannelsens korridor. Et argument for et udvidet dannelsesbegreb

    DEFF Research Database (Denmark)

    Smedegaard Ernst Bengtsen, Søren

    til et eksistentielt fænomen, hvor det dannede individ risikerer sin egen viden, destabiliserer det kulturelle paradigme, han tilhører, samt stræber efter mærkelige, sære og bekymrende vidensformer. Denne artikel argumenterer for, at ingen af disse to modsatrettede dannelsesbegreber kan stå alene, men...

  8. Roman historique et Histoire dans le roman

    Directory of Open Access Journals (Sweden)

    Christine Di Benedetto


    Full Text Available Engager une réflexion sur le « roman historique » dans l’Espagne de l’après-transition démocratique conduit ici à aborder les questions, plus vastes, d’Histoire dans le roman et de roman de la mémoire. Mais les notions de passé et de présent et leurs rapports se définissent au regard de la situation particulière de l’Espagne. L’interprétation de la place qu’occupe le roman historique dans le panorama romanesque espagnol s’enrichit alors des perspectives issues de la philosophie et de la sociologie.Au confluent de ces démarches, des exemples tirés de la littérature contemporaine et étayés par des éléments d’analyse fictionnelle et narrative figurent trois niveaux d’intégration de l’Histoire récente dans le roman espagnol. Et une identité en devenir se dessine, alors que la mémoire historique arrive clairement sur la scène littéraire en même temps qu’elle s’insinue dans les problématiques qui occupent la société espagnole de la fin du millénaire.Adentrarse en una reflexión sobre “la novela histórica” en la España de la post- transición democrática lleva aquí a acercarse a los temas, más amplios, de Historia en la novela y de novela de la memoria. Pero las nociones de pasado y de presente se definen en el ámbito de la situación peculiar de España, y de allí el vínculo cualitativo entre las dos. La interpretación del puesto que ocupa en la narrativa española se enriquece entonces de las perspectivas que proceden de la filosofía y de la sociología.En el confluente de estas modalidades reflexivas, unos ejemplos, sacados de la literatura contemporánea y estudiados gracias a elementos de análisis de la ficción y de la narración destacan tres niveles de integración de la Historia reciente en la novela española. De modo que una búsqueda identitaria se define, mientras la memoria histórica llega claramente al escenario literario, al mismo tiempo que se cuela dentro de las

  9. Recherche du boson de Higgs dans l'état final dimuonique et étude de l'asymétrie de production de la paire top antitop avec l'expérience DO auprès du Tevatron; Higgs boson search in the dimuonique final state and study of the top pair antitop production asymmetry with the DO experiment at the Tevatron.

    Energy Technology Data Exchange (ETDEWEB)

    Fauré, Alexandre [University of Paris-Sud, Orsay (France)


    Two high energy particle physics analyses are presented in this PhD report using events with two leptons oppositely charged and with missing transverse energy. These events are selected using 9.7 fb-1 of total pp collisions data collected with the DØ detector at the TeVatron at √s=1.96 TeV.The first analysis is the research of the Higgs boson decaying in the H→WW→μνμν channel. No significant excess above the background prediction is observed.Upper limits on Higgs boson production cross-section are computed in the standard model framework but also in the 4th generation of fermions and in the fermiophobic coupling to Higgs boson hypotheses. In order to validate the research methodology, the W boson pair production cross-section is measured.The second analysis is the measurement of the forward-backward asymmetry of the tt pair production. This is the first measurement in the dileptonic channel at DØ experiment. In this context, a new tt pair kinematic reconstruction is used (matrix element method) to give a raw measurement of the forward-backward asymmetry. Thanks to a dedicated calibration method, we give a final measurement of AFB=18.0 ± 6.0 (stat) ± 3.3 (syst).

  10. Charmless hadronic three-body decays of neutral $B$ mesons with a $K^0_s$ in the final state in the LHCb experiment: branching fractions and an amplitude analysis Désintégrations hadroniques à trois corps sans charme de mésons $B$ avec un $K^0_s$ dans l'état final dans l'expérience LHCb : mesure de rapports d'embranchement et une analyse en amplitude

    CERN Document Server


    This dissertation presents several studies of the decays of both $B^{0}$ and $B^{0}_{s}$ mesons to charmless three-body final states including a $K^{0}_{s}$ meson. They use the data recorded by the LHCb experiment during Run I of LHC, corresponding to an integrated luminosity of $\\int\\=3 fb^{-1}$ A first analysis consists of the measurement of the branching fractions of \\BdstoKshhp decays, where $h^{(')}$ designates a kaon or a pion. Preceding \\lhcb measurements of branching fractions for all decay channels, relative to that of $\\Bd\\to\\KS\\pip\\pim$, are updated. Furthermore, the primary goal of this analysis is to search for the, as yet, unobserved decay $\\Bs\\to\\KS\\Kp\\Km$. The relative branching fractions are measured to be: \\begin{align} \\frac{\\Br{\\BstoKsPiPi}}{\\Br{\\BdtoKsPiPi}} &= 0.26 \\pm 0.04\\mathrm{(stat.)} \\pm 0.02\\mathrm{(syst.)} \\pm 0.01\\mathrm{(f_s/f_d}\\mathrm{)},\

  11. ETS rearrangements in prostate cancer

    Institute of Scientific and Technical Information of China (English)

    Mark A Rubin


    Prostate cancer is a clinically and molecularly heterogeneous disease.Understanding the biologic underpinning of prostate cancer is necessary to best determine how biology is associated with the risk of disease progression and how this understanding might provide insight into the development of novel therapeutic approaches.The focus of this review is on the recently identified common ETS and non-ETS gene rearrangements in prostate cancer.Although multiple molecular alterations have been detected in prostate cancer,a basic understanding of gene fusion prostate cancer should help explain the clinical and biologic diversity,providing a rationale for a molecular subclassification of the disease.

  12. Production and Metabolism of Indole Acetic Acid in Root Nodules and Symbiont (Rhizobium undicola Isolated from Root Nodule of Aquatic Medicinal Legume Neptunia oleracea Lour.

    Directory of Open Access Journals (Sweden)

    Pallab Kumar Ghosh


    Full Text Available Indole acetic acid is a phytohormone which plays a vital role in plant growth and development. The purpose of this study was to shed some light on the production of IAA in roots, nodules, and symbionts of an aquatic legume Neptunia oleracea and its possible role in nodular symbiosis. The symbiont (N37 was isolated from nodules of this plant and identified as Rhizobium undicola based on biochemical characteristics, 16S rDNA sequence homology, and DNA-DNA hybridization results. The root nodules were found to contain more IAA and tryptophan than root; however, no detectable amount of IAA was found in root. The IAA metabolizing enzymes IAA oxidase, IAA peroxidase (E.C., and polyphenol oxidase (E.C. were higher in root than nodule but total phenol and IAA content were reversed. The strain N37 was found to produce copious amount of IAA in YEM broth medium with tryptophan and reached its stationary phase at 20 h. An enrichment of the medium with mannitol, ammonium sulphate, B12, and 4-hydroxybenzaldehyde was found to promote the IAA production. The presence of IAA metabolizing enzymes and IAA production with PGPR traits including ACC deaminase activity of the symbionts was essential for plant microbe interaction and nodule function.

  13. Rhizobium leguminosarum COMO ORGANISMO BIOCONTROLADOR DE LA INTERACCIÓN HOSPEDERO-PATÓGENO: CLAVEL (Dianthus caryophyllus – Fusarium Oxysporum f. sp. dianthi

    Directory of Open Access Journals (Sweden)

    Cheol Woo Lee Park


    Full Text Available Se investigó el efecto de biocontrol de Rhizobium leguminosarum (R. leguminosarum cepa B, contra Fusarium oxysporum f.sp.dianthi (FOD raza 2, en la interacción Clavel - FOD. Se utilizó la raza 2 de FOD por ser la de mayor patogenicidad y distribución en las fincas de cultivo de clavel en Colombia. Para ello se establecieron las condiciones de inoculación de FOD sobre cultivos establecidos de R . leguminosarum, variando la concentración in vitro de la bacteria. Se encontró una reducción en el número de microconidias hasta un 90% y una inhibición en el crecimiento radial del patógeno de hasta un 71 %. En el ensayo de microcultivo dual se detectó fraccionamiento de las hifas después de 48 horas de incubación con R . leguminosarum En el ensayo in vivo, los esquejes de clavel Raggio di solé, variedad susceptible al patógeno, fueron inoculados con 45.0 x 10 células de R. leguminosarum por matero, mostrando una severidad inferior al 5%, una incidencia menor del 20% y una reducción del índice de la enfermedad hasta de un 92% en presencia del patógeno.

  14. The Aquaeous Extract of Root Nodules Vigna radiata (rnVr which Inoculated by Rhizobium as an Orally Available Anemia Therapeutic Candidate

    Directory of Open Access Journals (Sweden)

    Dewi Hidayati


    Full Text Available The extract of root nodules Vigna radiata (rnVr which inoculated by Rhizobium is considered beneficial as an orally available anemia therapeutic candidate, because it contain the leghemoglobin. The positive control mice (group I were fed with the high nutrient pellet.The twelve mice (Mus musculus was treated with the “taking rice pellet” that representing the low nutrient food for 21 days until they suffered anemia. Then, the anemia mice were treated orally with rnVr in different concentration groups:II. 0% III.33%; IV.67% and V.100%, respectively and fed with the “aking rice pellet”. After 14 days, the blood mice were collected from orbital sinus. The hemoglobin (Hb concentration were analyzed by spectrophotometry and blood plasma profile protein were analyzed with electrophoresis (SDS-PAGE. All anemia mice that treated with rnVr showed the increasing of Hb and group that treated with 100% extract of rnVr could reach a normal Hb value, raising from 9.85 to 12.68 g/dL. There were observed the proteins which have molecule weight 36.5 and 35.7 kDa that indicated the existing erythropoietin. The increasing haemoglobin concentration and erythropoietin suggested if extract of rnVr could increasing red blood production and potential as an orally available anemia therapeutic candidate.

  15. Rhizobium leguminosarum bv. viciae 3841 Adapts to 2,4-Dichlorophenoxyacetic Acid with "Auxin-Like" Morphological Changes, Cell Envelope Remodeling and Upregulation of Central Metabolic Pathways.

    Directory of Open Access Journals (Sweden)

    Supriya V Bhat

    Full Text Available There is a growing need to characterize the effects of environmental stressors at the molecular level on model organisms with the ever increasing number and variety of anthropogenic chemical pollutants. The herbicide 2,4-dichlorophenoxyacetic acid (2,4-D, as one of the most widely applied pesticides in the world, is one such example. This herbicide is known to have non-targeted undesirable effects on humans, animals and soil microbes, but specific molecular targets at sublethal levels are unknown. In this study, we have used Rhizobium leguminosarum bv. viciae 3841 (Rlv as a nitrogen fixing, beneficial model soil organism to characterize the effects of 2,4-D. Using metabolomics and advanced microscopy we determined specific target pathways in the Rlv metabolic network and consequent changes to its phenotype, surface ultrastructure, and physical properties during sublethal 2,4-D exposure. Auxin and 2,4-D, its structural analogue, showed common morphological changes in vitro which were similar to bacteroids isolated from plant nodules, implying that these changes are related to bacteroid differentiation required for nitrogen fixation. Rlv showed remarkable adaptation capabilities in response to the herbicide, with changes to integral pathways of cellular metabolism and the potential to assimilate 2,4-D with consequent changes to its physical and structural properties. This study identifies biomarkers of 2,4-D in Rlv and offers valuable insights into the mode-of-action of 2,4-D in soil bacteria.

  16. The cloned 1-aminocyclopropane-1-carboxylate (ACC) deaminase gene from Sinorhizobium sp. strain BL3 in Rhizobium sp. strain TAL1145 promotes nodulation and growth of Leucaena leucocephala. (United States)

    Tittabutr, Panlada; Awaya, Jonathan D; Li, Qing X; Borthakur, Dulal


    The objective of this study was to determine the role of 1-aminocyclopropane-1-carboxylate (ACC) deaminase of symbionts in nodulation and growth of Leucaena leucocephala. The acdS genes encoding ACC deaminase were cloned from Rhizobium sp. strain TAL1145 and Sinorhizobium sp. BL3 in multicopy plasmids, and transferred to TAL1145. The BL3-acdS gene greatly enhanced ACC deaminase activity in TAL1145 compared to the native acdS gene. The transconjugants of TAL1145 containing the native or BL3 acdS gene could grow in minimal media containing 1.5mM ACC, whereas BL3 could tolerate up to 3mM ACC. The TAL1145 acdS gene was inducible by mimosine and not by ACC, while the BL3 acdS gene was highly inducible by ACC and not by mimosine. The transconjugants of TAL1145 containing the native- and BL3-acdS genes formed nodules with greater number and sizes, and produced higher root mass on L. leucocephala than by TAL1145. This study shows that the introduction of multiple copies of the acdS gene increased ACC deaminase activities of TAL1145 and enhanced its symbiotic efficiency on L. leucocephala.

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

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    Ann M. Hirsch


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

  18. Genotypic and symbiotic diversity of Rhizobium populations associated with cultivated lentil and pea in sub-humid and semi-arid regions of Eastern Algeria. (United States)

    Riah, Nassira; Béna, Gilles; Djekoun, Abdelhamid; Heulin, Karine; de Lajudie, Philippe; Laguerre, Gisèle


    The genetic structure of rhizobia nodulating pea and lentil in Algeria, Northern Africa was determined. A total of 237 isolates were obtained from root nodules collected on lentil (Lens culinaris), proteaginous and forage pea (Pisum sativum) growing in two eco-climatic zones, sub-humid and semi-arid, in Eastern Algeria. They were characterised by PCR-restriction fragment length polymorphism (RFLP) of the 16S-23S rRNA intergenic region (IGS), and the nodD-F symbiotic region. The combination of these haplotypes allowed the isolates to be clustered into 26 distinct genotypes, and all isolates were classified as Rhizobium leguminosarum. Symbiotic marker variation (nodD-F) was low but with the predominance of one nod haplotype (g), which had been recovered previously at a high frequency in Europe. Sequence analysis of the IGS further confirmed its high variability in the studied strains. An AMOVA analysis showed highly significant differentiation in the IGS haplotype distribution between populations from both eco-climatic zones. This differentiation was reflected by differences in dominant genotype frequencies. Conversely, no host plant effect was detected. The nodD gene sequence-based phylogeny suggested that symbiotic gene diversity in pea and lentil nodulating rhizobial populations in Algeria was low compared to that reported elsewhere in the world.

  19. 青蒿素对根瘤菌化感效应研究%Studies on allelopathic effect of artemisinin on rhizobium

    Institute of Scientific and Technical Information of China (English)

    李倩; 吴叶宽; 黄建国


    目的:研究黄花蒿释放的化感物质——青蒿素对根瘤菌的化感效应.方法:试验选用快生型和慢生型2株菜豆根瘤菌,在青蒿素质量浓度为0,20,40,80 mg·L-的根瘤菌液体培养基中培养,分别测定在不同青蒿素浓度下根瘤菌的生长曲线、碳源利用率、胞外蛋白酶、酸性磷酸酶和根瘤的固氮酶活性.结果:青蒿素极显著的抑制根瘤菌的繁殖生长,在培养液中加入40 mg.L-1青蒿素培养8h,根瘤菌的数目不到正常培养的一半.随着青蒿素浓度的增加,根瘤菌对蔗糖和葡萄糖的利用速率显著降低,青蒿素妨碍根瘤菌对碳源的吸收利用可能是抑制它们繁殖生长的重要原因之一.此外,根瘤菌胞外蛋白酶和磷酸酶的活性随青蒿素浓度的增加而降低,说明黄花蒿释放的青蒿素可能抑制根瘤形成,并干扰类菌体和寄主细胞之间的能量供需关系.固氮酶活性(y)与培养基中的青蒿素浓度(x)可用y=e-ax+b表示.当培养基中的青蒿素浓度达到48 mg·L-1时,固氮酶的活性几乎为0.因此,在形成根瘤后,土壤中的青蒿素也可能使根瘤丧失固氮活性.结论:在黄花篙种植的土壤中,它们释放的青蒿素对根瘤菌繁殖生长、根瘤形成和生物固氮的抑制作用可能进一步影响菜豆的氮源供应和生长发育,造成减产.%Two strains of bean rhizobia, Rhizobium vigna 01 (slow-growing Rhizobium) and Rh. vigna 03 (fast-growing Rhi-zobium) , were adopted to study allelopathic effect of artemisinin on the rhizobia. The results showed a significant inhibition of the reproduction and growth of rhizobium by artemisinin. After about 8 hours by adding 40 mg ·L-1 artemisinin into the culture medium, the number of rhizobia was less than half of those in normal culture. The utilization of sucrose and glucose by rhizobia decreased significantly as the concentration of artemisinin increased in the culture medium, which could be one of the main reasons

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

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