| phylogenetic position of rhizobium sp. strain or 191, a symbiont of both medicago sativa and phaseolus vulgaris, based on partial sequences of the 16s rrna and nifh genes. | phenotypic and dna sequence comparisons are presented for eight rhizobium isolates that were cultured from field-grown alfalfa (medicago sativa l.) in oregon. these isolates were previously shown to nodulate both alfalfa and common bean (phaseolus vulgaris (l.) savi.). the objective of the present study was to determine their phylogenetic relationships to the normal symbionts of these plants, rhizobium meliloti and rhizobium leguminosarum biovar phaseoli, respectively. phenotypically, the oregon ... | 1992 | 1377901 |
| molecular and symbiotic characterization of exopolysaccharide-deficient mutants of rhizobium tropici strain ciat899. | we studied the symbiotic behaviour of 20 independent tn5 mutants of rhizobium tropici strain ciat899 that were deficient in exopolysaccharide (eps) production. the mutants produced non-mucoid colonies, were motile, grew in broth cultures at rates similar to those of the parent, and produced significantly less eps than did ciat899 in broth culture. a genomic library of strain ciat899, constructed in pla2917, was mobilized into all of the mutants, and cosmids that restored eps production were iden ... | 1992 | 1453954 |
| rhizobium tropici, a novel species nodulating phaseolus vulgaris l. beans and leucaena sp. trees. | a new rhizobium species that nodulates phaseolus vulgaris l. and leucaena spp. is proposed on the basis of the results of multilocus enzyme electrophoresis, dna-dna hybridization, an analysis of ribosomal dna organization, a sequence analysis of 16s rdna, and an analysis of phenotypic characteristics. this taxon, rhizobium tropici sp. nov., was previously named rhizobium leguminosarum biovar phaseoli (type ii strains) and was recognized by its host range (which includes leucaena spp.) and nif ge ... | 1991 | 1715738 |
| cloning of nod gene regions from mesquite rhizobia and bradyrhizobia and nucleotide sequence of the nodd gene from mesquite rhizobia. | nitrogen-fixing symbiosis between bacteria and the tree legume mesquite (prosopis glandulosa) is important for the maintenance of many desert ecosystems. genes essential for nodulation and for extending the host range to mesquite were isolated from cosmid libraries of rhizobium (mesquite) sp. strain hw17b and bradyrhizobium (mesquite) sp. strain hw10h and were shown to be closely linked. all of the cosmid clones of rhizobia that extended the host range of rhizobium (parasponia) sp. strain ngr234 ... | 1995 | 7574650 |
| rhizobium tropici nodulation factor sulfation is limited by the quantity of activated form of sulfate. | rhizobium tropici is a broad host-range symbiont of phaseolus vulgaris. this bacterium produces a mixture of sulfated and non-sulfated n-methylated pentameric nodulation (nod) factors. to understand the genetic bases of the partial sulfation of r. tropici nod factors, which might be involved in the broad host-range of this species, we introduced in r. tropici cfn299 the recombinant plasmid pgmi515 carrying a set of nodulation (nod) genes of r. meliloti, including those involved in the sulfation ... | 1995 | 7635216 |
| fermentative and aerobic metabolism in rhizobium etli. | strains of rhizobium etli, rhizobium meliloti, and rhizobium tropici decreased their capacity to grow after successive subcultures in minimal medium, with a pattern characteristic for each species. during the growth of r. etli ce 3 in minimal medium (mm), a fermentation-like response was apparent: the o2 content was reduced and, simultaneously, organic acids and amino acids were excreted and poly-beta-hydroxybutyrate (phb) was accumulated. some of the organic acids excreted into the medium were ... | 1995 | 7768801 |
| the nods gene of rhizobium tropici strain ciat899 is necessary for nodulation on phaseolus vulgaris and on leucaena leucocephala. | rhizobium tropici strain ciat899 induces nitrogen-fixing nodules on the roots of a wide range of tropical legumes, including phaseolus vulgaris and leucaena leucocephala. previously, a dna region of the ciat899 psym plasmid containing the common nodulation genes nodabc and one of the nodd alleles was characterized (p. van rhijn, b. feys, c. verreth, and j. vanderleyden, j. bacteriol. 175: 438-447, 1993). as reported here, the region immediately downstream of nodc contains the nodsu genes. the nu ... | 1995 | 7772799 |
| a rhizobium tropici dna region carrying the amino-terminal half of a nodd gene and a nod-box-like sequence confers host-range extension. | rhizobium tropici ciat899 is a broad-host-range strain that, in addition to phaseolus, nodulates other plant legumes such as leucaena and macroptilium. the narrow-host-range of rhizobium leguminosarum biovars phaseoli (strain ce3) and trifolii (strain rs1051) can be extended to leucaena esculenta and phaseolus vulgaris plants, respectively, by the introduction of a dna fragment 521 bp long, which carries 128 amino acids of the amino-terminal region of a nodd gene from r. tropici, as well as a pu ... | 1993 | 7934929 |
| the adaptive acid tolerance response in root nodule bacteria and escherichia coli. | root nodule bacteria and escherichia coli show an adaptive acid tolerance response when grown under mildly acidic conditions. this is defined in terms of the rate of cell death upon exposure to acid shock at ph 3.0 and expressed in terms of a decimal reduction time, d. the d values varied with the strain and the ph of the culture medium. early exponential phase cells of three strains of rhizobium leguminosarum (wu95, 3001 and wsm710) had d values of 1, 6 and 5 min respectively when grown at ph 7 ... | 1994 | 8002711 |
| cytochrome aa3 gene regulation in members of the family rhizobiaceae: comparison of copper and oxygen effects in bradyrhizobium japonicum and rhizobium tropici. | dithionite-reduced minus ferricyanide-oxidized difference spectra on membranes from rhizobium tropici (formerly rhizobium leguminosarum bv. phaseoli) incubated at progressively lower o2 concentrations showed only a slight concomitant decrease in a603, the alpha-peak of cytochrome aa3. in contrast to previous results on bradyrhizobium japonicum, r. tropici showed no significant o2-mediated reduction in the level of either coxa transcription or cytochrome aa3 activity (as measured by ascorbate-n,n ... | 1994 | 8117073 |
| classification of the uptake hydrogenase-positive (hup+) bean rhizobia as rhizobium tropici. | phenotypic and genetic characterization indicated that hup+ bean rhizobial strains are type iia and type iib rhizobium tropici. the hup+ strain usda 2840, which did not cluster with either of the two types of r. tropici in a restriction fragment length polymorphism analysis, had electrophoretic patterns of pcr products generated with primers for repetitive extragenic palindromic and enterobacterial repetitive intergeneric consensus sequences similar to those of three reference strains of r. trop ... | 1994 | 8135515 |
| analysis of the lipid moiety of lipopolysaccharide from rhizobium tropici ciat899: identification of 29-hydroxytriacontanoic acid. | the lipid moieties of two lipid a's isolated from the phenolic and aqueous fractions of lipopolysaccharide from rhizobium tropici ciat899 have been studied. several 3-hydroxy fatty acids and two long-chain hydroxy fatty acids, 27-hydroxyoctacosanoic acid, and 29-hydroxytriacontanoic acid were identified; the ratios of these acids are the same in both lipid a's. these results can be used for chemotaxonomic purposes. | 1994 | 8157617 |
| nodulating ability of rhizobium tropici is conditioned by a plasmid-encoded citrate synthase. | rhizobium species elicit the formation of nitrogen-fixing root nodules through a complex interaction between bacteria and plants. various bacterial genes involved in the nodulation and nitrogen-fixation processes have been described and most have been localized on the symbiotic plasmids (psym). we have found a gene encoding citrate synthase on the psym plasmid of rhizobium tropici, a species that forms nitrogen-fixing nodules on the roots of beans (phaseolus vulgaris) and trees (leucaena spp.). ... | 1994 | 8170393 |
| proposal for rejection of agrobacterium tumefaciens and revised descriptions for the genus agrobacterium and for agrobacterium radiobacter and agrobacterium rhizogenes. | the 16s rrna sequences of seven representative agrobacterium strains, eight representative rhizobium strains, and the type strains of azorhizobium caulinodans and bradyrhizobium japonicum were determined. these strains included the type strains of agrobacterium tumefaciens, agrobacterium rhizogenes, agrobacterium radiobacter, agrobacterium vitis, agrobacterium rubi, rhizobium fredii, rhizobium galegae, rhizobium huakuii, rhizobium leguminosarum, rhizobium loti, rhizobium meliloti, and rhizobium ... | 1993 | 8240952 |
| genomic heterogeneity among french rhizobium strains isolated from phaseolus vulgaris l. | levels of dna relatedness between strains isolated from root nodules of phaseolus vulgaris and reference strains of different rhizobium species were determined by performing dna-dna hybridization experiments (s1 nuclease method). the nine strains examined were members of three genomic groups previously delineated by a restriction fragment length polymorphism analysis among strains isolated from p. vulgaris at different sites in france. in agreement with the results of the restriction fragment le ... | 1993 | 8240956 |
| nodulation factors from rhizobium tropici are sulfated or nonsulfated chitopentasaccharides containing an n-methyl-n-acylglucosaminyl terminus. | phaseolus vulgaris (common bean) can be nodulated by several rhizobium species. among them, rhizobium tropici has a relatively broad host range, as it is able to infect beans, leucaena trees, and several other legumes. this work describes the isolation and the characterization of extracellular factors (nod factors) whose production from r. tropici was triggered by the transcriptional activation of its nod genes. these factors consist of a chitopentaose backbone in which the n-acetyl group of the ... | 1993 | 8399187 |
| multiple copies of nodd in rhizobium tropici ciat899 and br816. | rhizobium tropici strains are able to nodulate a wide range of host plants: phaseolus vulgaris, leucaena spp., and macroptilium atropurpureum. we studied the nodd regulatory gene for nodulation of two r. tropici strains: ciat899, the reference r. tropici type iib strain, and br816, a heat-tolerant strain isolated from leucaena leucocephala. a survey revealed several nodd-hybridizing dna regions in both strains: five distinct regions in ciat899 and four distinct regions in br816. induction experi ... | 1993 | 8419293 |
| toward an integrated linkage map of common bean. iii. mapping genetic factors controlling host-bacteria interactions. | restriction fragment length polymorphism (rflp)-based genetic linkage maps allow us to dissect the genetic control of quantitative traits (qt) by locating individual quantitative trait loci (qtls) on the linkage map and determining their type of gene action and the magnitude of their contribution to the phenotype of the qt. we have performed such an analysis for two traits in common bean, involving interactions between the plant host and bacteria, namely rhizobium nodule number (nn) and resistan ... | 1993 | 8514141 |
| rhizobium tropici chromosomal citrate synthase gene. | two genes encoding citrate synthase, a key enzyme in the krebs cycle, have been found in rhizobium tropici. one of them is in the bacterial chromosome, while the other is in the symbiotic plasmid. we sequenced the chromosomal gene and found that it is very similar to the previously reported plasmidic gene sequence in its structural region but not in its regulatory region. the chromosomal gene is able to complement an escherichia coli citrate synthase mutant. in r. tropici, a mutant in the chromo ... | 1995 | 8526514 |
| structural analysis of the o-antigen of the lipopolysaccharide of rhizobium tropici ciat899. | the structure of the o-antigen chain of the lipopolysaccharide isolated from rhizobium tropici ciat899, by the phenol-water procedure, and recovered from the phenol layer, has been investigated by hydrolysis, methylation analysis and 1d and 2d 1h and 13c nmr spectroscopy of the complete polysaccharide and of oligosaccharides obtained by partial hydrolysis. the o-antigen has the repeating unit [formula: see text] | 1995 | 8529224 |
| phylogenetic relationships among rhizobium species nodulating the common bean (phaseolus vulgaris l.). | the phylogenetic relationships among rhizobium species that nodulate phaseolus vulgaris (common bean) were determined by directly sequencing the amplified 16s ribosomal dna genes of these organisms. the bean strains formed four separate clusters. one cluster was composed of rhizobium leguminosarum bv. trifolii, r. leguminosarum bv. viciae, and r. leguminosarum bv. phaseoli. two other clusters comprised rhizobium etli and rhizobium tropici, and the fourth cluster contained a single bean-nodulatin ... | 1996 | 8573502 |
| solution structure of the trisaccharide and hexasaccharide fragments of the o-antigen of the lipopolysaccharide of rhizobium tropici ciat899. | | 1995 | 8593631 |
| conservation of pcaq, a transcriptional activator of pca genes for catabolism of phenolic compounds, in agrobacterium tumefaciens and rhizobium species. | in agrobacterium tumefaciens a348, control of five genes for catabolism of the phenolic compound protocatechuate to beta-ketoadipate is exerted by the gene pcaq. the product of pcaq is a transcriptional activator which is distinct from regulators of the beta-ketoadipate pathway characterized in other bacterial groups. an investigation of whether pcaq is present and conserved in related rhizobium species employed southern hybridization and an agrobacterial pcad::lacz promoter probe plasmid. these ... | 1996 | 8655573 |
| isolation and characterization of rhizobium tropici nod factor sulfation genes. | rhizobium tropici produces a mixture of sulfated and non-sulfated nod factors. the genes responsible for the sulfation process in r. tropici strain cfn299 were cloned and sequenced. these genes are homologous to the nodp, nodq, and nodh genes from r. meliloti. the identity among the two species is 75% for nodp, 74% for nodq, and 69% for nodh. nodh resembles sulfotransferases in general and nodq has the characteristic purine-binding motifs and the paps 3'-phosphoadenosine 5'-phosphosulfate) motif ... | 1996 | 8755625 |
| in rhizobium meliloti, the operon associated with the nod box n5 comprises nodl, noea and noeb, three host-range genes specifically required for the nodulation of particular medicago species. | in rhizobium meliloti, the genes required for nodulation of legume hosts are under the control of dna regulatory sequences called nod boxes. in this paper, we have characterized three host-specific nodulation genes, which form a flavonoid-inducible operon down-stream of the nod box n5. the first gene of this operon is identical to the nodl gene identified by baev and kondorosi (1992) in r. meliloti strain ak631. the product of the second gene, noea, presents some homology with a methyltransferas ... | 1995 | 8801423 |
| characterization of rhizobium tropici ciat899 nodulation factors: the role of nodh and nodpq genes in their sulfation. | we have purified and characterized the nodulation factors produced by rhizobium tropici ciat899. this strain produces a large variety of nodulation factors, these being a mixture of sulfated or nonsulfated penta- or tetra-chito-oligosaccharides to which any of six different fatty acyl moieties may be attached to nitrogen of the nonreducing terminal residue. in this mixture we have also found methylated or nonmethylated lipo-chitin oligosaccharides. here we describe a novel lipo-chitin-oligosacch ... | 1996 | 8850086 |
| a 150-megadalton plasmid in rhizobium etli strain tal182 contains genes for nodulation competitiveness on phaseolus vulgaris l. | rhizobium etli tal182, a competitive strain for the nodulation of phaseolus beans, occupied more than 99% of the nodules when co-inoculated in various proportions with rhizobium tal1145 or rhizobium tropici ciat899. two overlapping cosmid clones, puhr68 and puhr69, containing genes for nodulation competitiveness from tal182, were isolated by functional complementation of strain tal1145. using one of these cosmid clones, we constructed two tn5-insertion mutants of tal182 defective in nodulation c ... | 1996 | 8864213 |
| the noda proteins of rhizobium meliloti and rhizobium tropici specify the n-acylation of nod factors by different fatty acids. | rhizobia synthesize mono-n-acylated chitooligosaccharide signals, called nod factors, that are required for the specific infection and nodulation of their legume hosts. the biosynthesis of nod factors is under the control of nodulation (nod) genes, including the nodabc genes present in all rhizobial species. the n-acyl substitution can vary between species and can play a role in host specificity. in rhizobium meliloti, an alfalfa symbiont, the acyl chain is a c16 unsaturated or a (omega-1) hydro ... | 1996 | 8930915 |
| the common nodabc genes of rhizobium meliloti are host-range determinants. | symbiotic bacteria of the genus rhizobium synthesize lipo-chitooligosaccharides, called nod factors (nfs), which act as morphogenic signal molecules on legume hosts. the common nodabc genes, present in all rhizobium species, are required for the synthesis of the core structure of nfs. nodc is an n-acetylglucosaminyltransferase, and nodb is a chitooligosaccharide deacetylase; noda is involved in n-acylation of the aminosugar backbone. specific nod genes are involved in diverse nf substitutions th ... | 1996 | 8986807 |
| identification of soil bacteria expressing a symbiotic plasmid from rhizobium leguminosarum bv. trofolii. | a hundred strains of non-nodulating, gram-negative, rod-shaped bacteria were isolated from clover-ryegrass pastures on three different soil types and from a sandy loam under lupins. when crossed with escherichia coli pn200 containing the cointegrate plasmid ppn1, 11 transconjugants gained the ability to form nodules on the roots of white clover (trifolium repens cv. grasslands huia). a noda probe indicated that they had gained nodulation genes. the identities of these 11 strains and 4 others der ... | 1997 | 9090106 |
| generation of rhizobium strains with improved symbiotic properties by random dna amplification (rda) | to select for bacterial strains with enhanced phenotypes, random fragments of a whole genome, or a defined region of the genome, are cloned in a nonreplicating vector. the resulting plasmids are integrated by recombination into the homologous dna region of the original strain. integration gives rise to a nontandem direct duplication of the corresponding dna region separated by the vector moiety of the plasmid. recombination between the direct repeats leads to tandem duplication and further ampli ... | 1997 | 9181580 |
| rhizobium gallicum sp. nov. and rhizobium giardinii sp. nov., from phaseolus vulgaris nodules. | thirty-one strains of two new genomic species (genomic species 1 and 2) of rhizobia isolated from root nodules of phaseolus vulgaris and originating from various locations in france were compared with reference strains of rhizobia by performing a numerical analysis of 64 phenotypic features. each genomic species formed a distinct phenon and was separated from the other rhizobial species. a comparison of the complete 16s rrna gene sequences of a representative of genomic species 1 (strain r602spt ... | 1997 | 9336898 |
| classification of austrian rhizobia and the mexican isolate fl27 obtained from phaseolus vulgaris l. as rhizobium gallicum. | the phylogenetic positions of four rhizobial strains obtained from nodules of common bean plants (phaseolus vulgaris l.) grown in an austrian soil and of the mexican bean isolate fl27 are described. analysis of the 16s rrna genes revealed sequences almost identical to that of the rhizobium gallicum type strain, r602sp, with a maximum of two nucleotide substitutions. comparison of the 16s rrna gene sequences with those from other bacteria indicated highest similarity to rhizobium sp. strain ok-50 ... | 1997 | 9336913 |
| three phylogenetic groups of noda and nifh genes in sinorhizobium and mesorhizobium isolates from leguminous trees growing in africa and latin america. | the diversity and phylogeny of noda and nifh genes were studied by using 52 rhizobial isolates from acacia senegal, prosopis chilensis, and related leguminous trees growing in africa and latin america. all of the strains had similar host ranges and belonged to the genera sinorhizobium and mesorhizobium, as previously determined by 16s rrna gene sequence analysis. the restriction patterns and a sequence analysis of the noda and nifh genes divided the strains into the following three distinct grou ... | 1998 | 9464375 |
| luxi- and luxr-homologous genes of rhizobium etli cnpaf512 contribute to synthesis of autoinducer molecules and nodulation of phaseolus vulgaris. | autoinduction plays an important role in intercellular communication among symbiotic and pathogenic gram-negative bacteria. we report here that a nitrogen-fixing symbiont of phaseolus vulgaris, rhizobium etli cnpaf512, produces at least seven different autoinducer molecules. one of them exhibits a growth-inhibitory effect like that of the bacteriocin small [n-(3r-hydroxy-7-cis-tetradecanoyl)-l-homoserine lactone]. at least two of the other autoinducers are synthesized by a luxi-homologous autoin ... | 1998 | 9473034 |
| rhizobium mongolense sp. nov. is one of three rhizobial genotypes identified which nodulate and form nitrogen-fixing symbioses with medicago ruthenica [(l.) ledebour]. | medicago ruthenica [(l.) ledebour] is native to inner mongolia where rhizosphere samples were collected for the isolation of 106 rhizobial cultures. besides nodulating the original trap host, the isolates formed nitrogen-fixing symbioses with phaseolus vulgaris. only half of the isolates nodulated alfalfa (medicago sativa), but these did not form nitrogen-fixing symbioses. rhizobium tropici also formed nitrogen-fixing symbioses with medicago ruthenica. a total of 56 distinctive multilocus electr ... | 1998 | 9542071 |
| genotypic characterization of bradyrhizobium strains nodulating endemic woody legumes of the canary islands by pcr-restriction fragment length polymorphism analysis of genes encoding 16s rrna (16s rdna) and 16s-23s rdna intergenic spacers, repetitive extragenic palindromic pcr genomic fingerprinting, and partial 16s rdna sequencing. | we present a phylogenetic analysis of nine strains of symbiotic nitrogen-fixing bacteria isolated from nodules of tagasaste (chamaecytisus proliferus) and other endemic woody legumes of the canary islands, spain. these and several reference strains were characterized genotypically at different levels of taxonomic resolution by computer-assisted analysis of 16s ribosomal dna (rdna) pcr-restriction fragment length polymorphisms (pcr-rflps), 16s-23s rdna intergenic spacer (igs) rflps, and repetitiv ... | 1998 | 9603820 |
| genes essential for nod factor production and nodulation are located on a symbiotic amplicon (amprtrcfn299pc60) in rhizobium tropici. | amplifiable dna regions (amplicons) have been identified in the genome of rhizobium etli. here we report the isolation and molecular characterization of a symbiotic amplicon of rhizobium tropici. to search for symbiotic amplicons, a cartridge containing a kanamycin resistance marker that responds to gene dosage and conditional origins of replication and transfer was inserted in the nodulation region of the symbiotic plasmid (psym) of r. tropici cfn299. derivatives harboring amplifications were s ... | 1998 | 9603874 |
| acylation of escherichia coli hemolysin: a unique protein lipidation mechanism underlying toxin function. | the pore-forming hemolysin (hlya) of escherichia coli represents a unique class of bacterial toxins that require a posttranslational modification for activity. the inactive protoxin pro-hlya is activated intracellularly by amide linkage of fatty acids to two internal lysine residues 126 amino acids apart, directed by the cosynthesized hlyc protein with acyl carrier protein as the fatty acid donor. this action distinguishes hlyc from all bacterial acyltransferases such as the lipid a, lux-specifi ... | 1998 | 9618444 |
| rhizobium tropici teu genes involved in specific uptake of phaseolus vulgaris bean-exudate compounds. | rhizobium tropici nodulates and fixes nitrogen in bean. in the r. tropici strain cfn299 we identified and characterized teu genes (tropici exudate uptake) induced by bean root exudates, localized by insertion of a promoter-less tn5-gusa1 transposon. teu genes are present on a plasmid of around 185 kb that is conserved in all r. tropici strains. proteins encoded by teu genes show similarity to abc transporters, specifically to ribose transport proteins. no induction of the teu genes was obtained ... | 1998 | 9671027 |
| prevalence of the rhizobium etli-like allele in genes coding for 16s rrna among the indigenous rhizobial populations found associated with wild beans from the southern andes in argentina. | a collection of rhizobial isolates from nodules of wild beans, phaseolus vulgaris var. aborigineus, found growing in virgin lands in 17 geographically separate sites in northwest argentina was characterized on the basis of host range, growth, hybridization to a nifh probe, analysis of genes coding for 16s rrna (16s rdna), dna fingerprinting, and plasmid profiles. nodules in field-collected wild bean plants were largely dominated by rhizobia carrying the 16s rdna allele of rhizobium etli. a simil ... | 1998 | 9726909 |
| poly-beta-hydroxybutyrate turnover in azorhizobium caulinodans is required for growth and affects nifa expression. | azorhizobium caulinodans is able to fix nitrogen in the free-living state and in symbiosis with the tropical legume sesbania rostrata. the bacteria accumulate poly-beta-hydroxybutyrate (phb) under both conditions. the structural gene for phb synthase, phbc, was inactivated by insertion of an interposon. the mutant strains obtained were devoid of phb, impaired in their growth properties, totally devoid of nitrogenase activity ex planta (nif-), and affected in nucleotide pools and induced fix- nod ... | 1998 | 9748438 |
| molecular diversity of rhizobia occurring on native shrubby legumes in southeastern australia | the structure of rhizobial communities nodulating native shrubby legumes in open eucalypt forest of southeastern australia was investigated by a molecular approach. twenty-one genomic species were characterized by small-subunit ribosomal dna pcr-restriction fragment length polymorphism and phylogenetic analyses, among 745 rhizobial strains isolated from nodules sampled on 32 different legume host species at 12 sites. among these rhizobial genomic species, 16 belonged to the bradyrhizobium subgro ... | 1998 | 9758831 |
| sulfation of nod factors via nodhpq is nodd independent in rhizobium tropici ciat899. | a cosmid from the rhizobium tropici ciat899 symbiotic plasmid, containing most of the nodulation genes described in this strain, has been isolated. although this cosmid does not carry a nodd gene, it confers ability to heterologous rhizobium spp. to nodulate r. tropici hosts (phaseolus vulgaris, macroptilium atropurpureum, and leucaena leucocephala). the observed phenotype is due to constitutive expression of the nodabcsuij operon, which has lost its regulatory region and is expressed from a pro ... | 1998 | 9768515 |
| isolation and sequencing of a second rhizobium tropici cfn299 genetic locus that contains genes homologous to amino acid sulphate activation genes. | a rhizobium tropici cfn299 dna region, homologous to genes involved in nod factor synthesis and amino acid sulphate activation, was isolated from a genome library. dna sequence analysis revealed two open reading frames, orf1 and orf2. orf1 showed highest sequence similarity to the escherichia coli cysd gene while orf2 is closely related to rhizobium sp. n33 nodq. however, the orf2 deduced peptide is 152 amino acids shorter than rhizobium sp. n33 nodq, and lacks the 3'-phosphoadenosine 5'-phospho ... | 1998 | 9773278 |
| mutants of rhizobium tropici strain ciat899 that do not induce chlorosis in plants. | type b strains of rhizobium tropici induce severe foliar chlorosis when applied at planting to seeds of symbiotic host and non-host dicotyledonous plants. a tn5-induced mutant, designated ct4812, or r. tropici strain ciat899 that was unable to induce chlorosis was isolated. cloning and sequencing of the dna flanking the transposon in ct4812 revealed that the tn5 insertion is located in a gene similar to glnd, which encodes uridylyltransferase/uridylyl-removing enzyme in enteric bacteria. two mar ... | 1998 | 9782510 |
| a stomatin-like protein encoded by the slp gene of rhizobium etli is required for nodulation competitiveness on the common bean. | rhizobium etli strain tal182 is a competitive strain for effective nodulation of beans. from this strain, a novel gene was isolated, slp, which is 669 bp in size and required for nodulation competition on the common bean. the slp knockout mutant of tal182 is defective in nodulation competition, shows reduced growth in the presence of 200 mm nacl, kcl or licl and is complemented by the cloned slp gene. the deduced amino acid sequence of slp shows 66-72% similarity to stomatin proteins of homo sap ... | 1998 | 9782511 |
| three replicons of rhizobium sp. strain ngr234 harbor symbiotic gene sequences. | rhizobium sp. strain ngr234 contains three replicons: the symbiotic plasmid or pngr234a, a megaplasmid (pngr234b), and the chromosome. symbiotic gene sequences not present in pngr234a were analyzed by hybridization. dna sequences homologous to the genes fixljknopqghis were found on the chromosome, while sequences homologous to nodpq and exobdflk were found on pngr234b. | 1998 | 9811668 |
| effect of canavanine from alfalfa seeds on the population biology of bacillus cereus | bacillus cereus uw85 suppresses diseases of alfalfa seedlings, although alfalfa seed exudate inhibits the growth of uw85 in culture (j. l. milner, s. j. raffel, b. j. lethbridge, and j. handelsman, appl. microbiol. biotechnol. 43:685-691, 1995). in this study, we determined the chemical basis for and biological role of the inhibitory activity. all of the alfalfa germ plasm tested included seeds that released inhibitory material. we purified the inhibitory material from one alfalfa cultivar and i ... | 1998 | 9835549 |
| genetic diversity and phylogeny of rhizobia that nodulate acacia spp. in morocco assessed by analysis of rrna genes | forty rhizobia nodulating four acacia species (a. gummifera, a. raddiana, a. cyanophylla, and a. horrida) were isolated from different sites in morocco. these rhizobia were compared by analyzing both the 16s rrna gene (rdna) and the 16s-23s rrna spacer by pcr with restriction fragment length polymorphism (rflp) analysis. analysis of the length of 16s-23s spacer showed a considerable diversity within these microsymbionts, but rflp analysis of the amplified spacer revealed no additional heterogene ... | 1998 | 9835582 |
| molecular genetics of the genus paracoccus: metabolically versatile bacteria with bioenergetic flexibility. | paracoccus denitrificans and its near relative paracoccus versutus (formerly known as thiobacilllus versutus) have been attracting increasing attention because the aerobic respiratory system of p. denitrificans has long been regarded as a model for that of the mitochondrion, with which there are many components (e.g., cytochrome aa3 oxidase) in common. members of the genus exhibit a great range of metabolic flexibility, particularly with respect to processes involving respiration. prominent exam ... | 1998 | 9841665 |
| multiple small heat shock proteins in rhizobia. | seven genes coding for small heat shock proteins (shsps) in bradyrhizobium japonicum have been identified. they are organized in five operons that are coordinately regulated by rose, a negatively cis-acting dna element. the deduced shsps can be divided into two separate classes: class a, consisting of proteins that show similarity to escherichia coli ibpa and ibpb, and class b, whose members display significant similarity to other shsps from prokaryotes and eukaryotes. two-dimensional gel electr ... | 1999 | 9864316 |
| symbiotic deficiencies associated with a coxwxyz mutant of bradyrhizobium japonicum | the terminal oxidase complexes encoded by coxmnop and coxwxyz were studied by analysis of mutations in each of the two oxidases. carbon monoxide difference spectra obtained from membranes of coxmnop mutant bacteroids were like those obtained for the wild type, whereas bacteroid membranes of a coxwxyz mutant were deficient in co-reactive cytochrome b. experiments involving cyanide inhibition of oxidase activity were consistent with the conclusion that the coxx mutant is deficient in a membrane-as ... | 1999 | 9872805 |
| accumulation of ppgpp in symbiotic and free-living nitrogen-fixing bacteria following amino acid starvation | following amino acid or ammonium starvation, ppgpp is accumulated by rhizobium meliloti strain 1021 but not by r. meliloti strain 41 or rhizobium tropici. azorhizobium caulinodans ors571 produced ppgpp following amino acid deprivation; however, the free-living nitrogen-fixing bacteria azotobacter vinelandii and azomonas agilis did not produce ppgpp. western blot analysis using anti-rela antibody demonstrated that r. meliloti strain 1021, azotobacter vinelandii and azorhizobium caulinodans cross- ... | 1999 | 9914311 |
| noll of rhizobium sp. strain ngr234 is required for o-acetyltransferase activity. | following (iso)flavonoid induction, nodulation genes of the symbiotic nitrogen-fixing bacterium rhizobium sp. strain ngr234 elaborate a large family of lipooligosaccharidic nod factors (nodngr factors). when secreted into the rhizosphere of compatible legumes, these signal molecules initiate root hair deformation and nodule development. the nonreducing glucosamine residue of nodngr factors are n acylated, n methylated, and mono- or biscarbamoylated, while position c-6 of the reducing extremity i ... | 1999 | 9922261 |
| topology of rbsc, a membrane component of the ribose transporter, belonging to the arah superfamily. | rbsc of escherichia coli is the hydrophobic membrane component of ribose uptake system classified as the atp-binding cassette transporter. to understand the structure and function of rbsc, its transmembrane topology was investigated by using 64 rbsc-phoa fusions isolated either specifically or randomly. in order to confirm the cytoplasmic location of the short c-terminal region (5 amino acids), inside-out or right-side-out membrane vesicles were generated, and the c-terminal region was found to ... | 1999 | 9922273 |
| discrimination of rhizobium tropici and r. leguminosarum strains by pcr-specific amplification of 16s-23s rdna spacer region fragments and denaturing gradient gel electrophoresis (dgge). | with the aim of detecting rhizobium species directly in the environment, specific pcr primers for rh. tropici and rh. leguminosarum were designed on the basis of sequence analysis of 16s-23s rdna spacer regions of several rh. tropici, rh. leguminosarum and agrobacterium rhizogenes strains. primer specificity was checked by comparison with available rdna spacer sequences in databases, and by pcr using dna from target and reference strains. sequence polymorphisms of rdna spacer fragments among str ... | 1999 | 10063643 |
| occurrence of choline and glycine betaine uptake and metabolism in the family rhizobiaceae and their roles in osmoprotection | the role of glycine betaine and choline in osmoprotection of various rhizobium, sinorhizobium, mesorhizobium, agrobacterium, and bradyrhizobium reference strains which display a large variation in salt tolerance was investigated. when externally provided, both compounds enhanced the growth of rhizobium tropici, sinorhizobium meliloti, sinorhizobium fredii, rhizobium galegae, agrobacterium tumefaciens, mesorhizobium loti, and mesorhizobium huakuii, demonstrating their utilization as osmoprotectan ... | 1999 | 10224003 |
| nodule-inducing activity of synthetic sinorhizobium meliloti nodulation factors and related lipo-chitooligosaccharides on alfalfa. importance of the acyl chain structure. | sinorhizobium meliloti nodulation factors (nfs) elicit a number of symbiotic responses in alfalfa (medicago sativa) roots. using a semiquantitative nodulation assay, we have shown that chemically synthesized nfs trigger nodule formation in the same range of concentrations (down to 10(-10) m) as natural nfs. the absence of o-sulfate or o-acetate substitutions resulted in a decrease in morphogenic activity of more than 100-fold and approximately 10-fold, respectively. to address the question of th ... | 1999 | 10318686 |
| increase in alfalfa nodulation, nitrogen fixation, and plant growth by specific dna amplification in sinorhizobium meliloti. | to improve symbiotic nitrogen fixation on alfalfa plants, sinorhizobium meliloti strains containing different average copy numbers of a symbiotic dna region were constructed by specific dna amplification (sda). a dna fragment containing a regulatory gene (nodd1), the common nodulation genes (nodabc), and an operon essential for nitrogen fixation (nifn) from the nod regulon region of the symbiotic plasmid psyma of s. meliloti was cloned into a plasmid unable to replicate in this organism. the pla ... | 1999 | 10347066 |
| cloning, sequencing, and characterization of the cgmb gene of sinorhizobium meliloti involved in cyclic beta-glucan biosynthesis. | periplasmic cyclic beta-glucans of rhizobium species provide important functions during plant infection and hypo-osmotic adaptation. in sinorhizobium meliloti (also known as rhizobium meliloti), these molecules are highly modified with phosphoglycerol and succinyl substituents. we have previously identified an s. meliloti tn5 insertion mutant, s9, which is specifically impaired in its ability to transfer phosphoglycerol substituents to the cyclic beta-glucan backbone (m. w. breedveld, j. a. hadl ... | 1999 | 10419956 |
| phaseolus vulgaris recognizes azorhizobium caulinodans nod factors with a variety of chemical substituents. | phaseolus vulgaris is a promiscuous host plant that can be nodulated by many different rhizobia representing a wide spectrum of nod factors. in this study, we introduced the rhizobium tropici cfn299 nod factor sulfation genes nodhpq into azorhizobium caulinodans. the a. caulinodans transconjugants produce nod factors that are mostly if not all sulfated and often with an arabinosyl residue as the reducing end glycosylation. using a. caulinodans mutant strains, affected in reducing end decorations ... | 1999 | 10494633 |
| interstrain variation of the polysaccharide b biosynthesis locus of bacteroides fragilis: characterization of the region from strain 638r. | the sequence and analysis of the capsular polysaccharide biosynthesis locus, ps b2, of bacteroides fragilis 638r are described, and the sequence is compared with that of the ps b1 biosynthesis locus of b. fragilis nctc 9343. two genes of the region, wcgd and wcgc, are shown by complementation to encode a udp-n-acetylglucosamine 2-epimerase and a udp-n-acetylmannosamine dehydrogenase, respectively. | 1999 | 10498737 |
| analysis of lipoxygenase mrna accumulation in the common bean (phaseolus vulgaris l.) during development and under stress conditions. | plant lipoxygenases (lox, ec 1.13.11.12) have been involved in processes such as stress responses and development. the levels of these enzymes and their corresponding mrnas are modulated during these processes as well as by different effectors such as jasmonic acid (ja), its methyl ester (meja) or abscisic acid (aba). a new lipoxygenase (lox) cdna clone, pvlox2, was isolated from a phaseolus vulgaris nodule library and used to study the lox mrna accumulation pattern in some developmental stages ... | 1999 | 10555305 |
| rhizobium-legume symbiosis and nitrogen fixation under severe conditions and in an arid climate. | biological n(2) fixation represents the major source of n input in agricultural soils including those in arid regions. the major n(2)-fixing systems are the symbiotic systems, which can play a significant role in improving the fertility and productivity of low-n soils. the rhizobium-legume symbioses have received most attention and have been examined extensively. the behavior of some n(2)-fixing systems under severe environmental conditions such as salt stress, drought stress, acidity, alkalinit ... | 1999 | 10585971 |
| citrate synthase mutants of sinorhizobium meliloti are ineffective and have altered cell surface polysaccharides. | the glta gene, encoding sinorhizobium meliloti 104a14 citrate synthase, was isolated by complementing an escherichia coli glta mutant. the s. meliloti glta gene was mutated by inserting a kanamycin resistance gene and then using homologous recombination to replace the wild-type glta with the glta::kan allele. the resulting strain, csdx1, was a glutamate auxotroph, and enzyme assays confirmed the absence of a requirement for glutamate. csdx1 did not grow on succinate, malate, aspartate, pyruvate, ... | 1999 | 10601220 |
| identification of a new class of 5'-adenylylsulfate (aps) reductases from sulfate-assimilating bacteria. | a gene was cloned from burkholderia cepacia dbo1 that is homologous with escherichia coli cysh encoding 3'-phosphoadenylylsulfate (paps) reductase. the b. cepacia gene is the most recent addition to a growing list of cysh homologs from a diverse group of sulfate-assimilating bacteria whose products show greater homology to plant 5'-adenylylsulfate (aps) reductase than they do to e. coli cysh. the evidence reported here shows that the cysh from one of the species, pseudomonas aeruginosa, encodes ... | 2000 | 10613872 |
| characterization of two inducible phosphate transport systems in rhizobium tropici. | rhizobium tropici forms nitrogen-fixing nodules on the roots of the common bean (phaseolus vulgaris). like other legume-rhizobium symbioses, the bean-r. tropici association is sensitive to the availability of phosphate (p(i)). to better understand phosphorus movement between the bacteroid and the host plant, p(i) transport was characterized in r. tropici. we observed two p(i) transport systems, a high-affinity system and a low-affinity system. to facilitate the study of these transport systems, ... | 2000 | 10618197 |
| a new chemolithoautotrophic arsenite-oxidizing bacterium isolated from a gold mine: phylogenetic, physiological, and preliminary biochemical studies. | a previously unknown chemolithoautotrophic arsenite-oxidizing bacterium has been isolated from a gold mine in the northern territory of australia. the organism, designated nt-26, was found to be a gram-negative motile rod with two subterminal flagella. in a minimal medium containing only arsenite as the electron donor (5 mm), oxygen as the electron acceptor, and carbon dioxide-bicarbonate as the carbon source, the doubling time for chemolithoautotrophic growth was 7.6 h. arsenite oxidation was f ... | 2000 | 10618208 |
| glutathione is involved in environmental stress responses in rhizobium tropici, including acid tolerance. | the isolation of rhizobial strains which exhibit an intrinsic tolerance to acidic conditions has been reported and has facilitated studies on the basic mechanisms underlying acid tolerance. rhizobium tropici strain ciat899 displays a high intrinsic tolerance to acidity and therefore was used in this work to study the molecular basis of bacterial responses to acid conditions and other environmental stresses. we generated a collection of r. tropici ciat899 mutants affected in acid tolerance using ... | 2000 | 10692382 |
| molecular basis of symbiotic promiscuity. | eukaryotes often form symbioses with microorganisms. among these, associations between plants and nitrogen-fixing bacteria are responsible for the nitrogen input into various ecological niches. plants of many different families have evolved the capacity to develop root or stem nodules with diverse genera of soil bacteria. of these, symbioses between legumes and rhizobia (azorhizobium, bradyrhizobium, mesorhizobium, and rhizobium) are the most important from an agricultural perspective. nitrogen- ... | 2000 | 10704479 |
| distribution of intervening sequences in the genes for 23s rrna and rrna fragmentation among strains of the salmonella reference collection b (sarb) and sarc sets. | intervening sequences (ivss) occur sporadically in several bacterial genera in the genes for 23s rrna at relatively conserved locations. they are cleaved after transcription and lead to the presence of fragmented rrna, which is incorporated into the ribosomes without religation but is nevertheless functional. the fragmentation of rrna and the number of ivss in all 72 strains of the salmonella reference collection b set and 16 strains of the salmonella reference collection c set, which have been ... | 2000 | 10714998 |
| analysis of cellular fatty acids and phenotypic relationships of agrobacterium, bradyrhizobium, mesorhizobium, rhizobium and sinorhizobium species using the sherlock microbial identification system. | previous studies have demonstrated that cellular fatty acid analysis is a useful tool for identifying unknown strains of rhizobia and establishing taxonomic relationships between the species. in this study, the fatty acid profiles of over 600 strains belonging to the genera agrobacterium, bradyrhizobium, mesorhizobium, rhizobium and sinorhizobium were evaluated using the gaschromatography-based sherlock microbial identification system (mis). data collected with the mis showed that the three phyl ... | 2000 | 10758890 |
| polyphasic characterization of rhizobia that nodulate phaseolus vulgaris in west africa (senegal and gambia). | fifty-eight new isolates were obtained from root nodules of common bean (phaseolus vulgaris) cultivated in soils originating from different agroecological areas in senegal and gambia (west africa). a polyphasic approach including both phenotypic and genotypic techniques was used to study the diversity of the 58 rhizobium isolates and to determine their taxonomic relationships with reference strains. all the techniques performed, analysis of multilocus enzyme electrophoretic patterns, sds-page pr ... | 2000 | 10826800 |
| prey range characterization, ribotyping, and diversity of soil and rhizosphere bdellovibrio spp. isolated on phytopathogenic bacteria. | thirty new bdellovibrio strains were isolated from an agricultural soil and from the rhizosphere of plants grown in that soil. using a combined molecular and culture-based approach, we found that the soil bdellovibrios included subpopulations of organisms that differed from rhizosphere bdellovibrios. thirteen soil and seven common bean rhizosphere bdellovibrio strains were isolated when pseudomonas corrugata was used as prey; seven and two soil strains were isolated when erwinia carotovora subsp ... | 2000 | 10831412 |
| rhizobitoxine production by bradyrhizobium elkanii enhances nodulation and competitiveness on macroptilium atropurpureum. | application of 1-aminoocyclopropane-1-carboxylic acid, an ethylene precursor, decreased nodulation of macroptilium atropurpureum by bradyrhizobium elkanii. b. elkanii produces rhizobitoxine, an ethylene synthesis inhibitor. elimination of rhizobitoxine production in b. elkanii increased ethylene evolution and decreased nodulation and competitiveness on m. atropurpureum. these results suggest that rhizobitoxine enhances nodulation and competitiveness of b. elkanii on m. atropurpureum. | 2000 | 10831453 |
| the common nodulation genes of astragalus sinicus rhizobia are conserved despite chromosomal diversity. | the nodulation genes of mesorhizobium sp. (astragalus sinicus) strain 7653r were cloned by functional complementation of sinorhizobium meliloti nod mutants. the common nod genes, nodd, noda, and nodbc, were identified by heterologous hybridization and sequence analysis. the noda gene was found to be separated from nodbc by approximately 22 kb and was divergently transcribed. the 2. 0-kb noddbc region was amplified by pcr from 24 rhizobial strains nodulating a. sinicus, which represented differen ... | 2000 | 10877796 |
| in rhizobium leguminosarum, nodd represses its own transcription by competing with rna polymerase for binding sites. | we isolated rna polymerase (rnap) from rhizobium leguminosarum, the nitrogen-fixing symbiont of peas and vicia: its 91 kda subunit, which is homologous to sigma(70) of escherichia coli rnap, is necessary for transcription of the regulatory nodd gene, which in the presence of certain flavonoids induces transcription of other nod genes that are needed for the early steps of infection. we also show that negative autoregulation of nodd was achieved through competition between rnap and nodd for their ... | 2000 | 10908336 |
| keys to symbiotic harmony. | | 2000 | 11004160 |
| nod factors and chitooligomers elicit an increase in cytosolic calcium in aequorin-expressing soybean cells. | rhizobial nod factors (nfs) function as nodulation signals that trigger symbiotic responses of leguminous host plants. nfs consist of a chitin oligomer backbone carrying a fatty acid at the non-reducing end. depending on the rhizobial strain, nfs carry additional substituents, which may determine host specificity. transgenic suspension-cultured soybean (glycine max [l.] merr.) cells expressing aequorin have been used to record cytosolic [ca(2+)] changes upon treatment with purified nfs and chiti ... | 2000 | 11027722 |
| bradyrhizobium sp. strains that nodulate the leguminous tree acacia albida produce fucosylated and partially sulfated nod factors. | we determined the structures of nod factors produced by six different bradyrhizobium sp. strains nodulating the legume tree acacia albida (syn. faidherbia albida). compounds from all strains were found to be similar, i.e., o-carbamoylated and substituted by an often sulfated methyl fucose and different from compounds produced by rhizobium-mesorhizobium-sinorhizobium strains nodulating other species of the acaciae tribe. | 2000 | 11055966 |
| genetic characterization of soybean rhizobia in paraguay. | the soybean is an exotic plant introduced in paraguay in this century; commercial cropping expanded after the 1970s. inoculation is practiced in just 15 to 20% of the cropping areas, but root nodulation occurs in most sites where soybeans grow. little is known about rhizobial diversity in south america, and no study has been performed in paraguay until this time. therefore, in this study, the molecular characterization of 78 rhizobial isolates from soybean root nodules, collected under field con ... | 2000 | 11055970 |
| a guab mutant strain of rhizobium tropici ciat899 pleiotropically defective in thermal tolerance and symbiosis. | rhizobium tropici strain ciat899 displays a high intrinsic thermal tolerance, and had been used in this work to study the molecular basis of bacterial responses to high temperature. we generated a collection of r. tropici ciat899 mutants affected in thermal tolerance using tns-luxab mutagenesis and described the characterization of a mutant strain, ciat899-10t, that fails to grow under conditions of high temperature. strain ciat899-10t carries a single transposon insertion in a gene showing a hi ... | 2000 | 11059489 |
| phylogenetic diversity of rhizobial strains nodulating robinia pseudoacacia l. | lack of knowledge exists regarding the diversity of rhizobial strains nodulating black locust (robinia pseudoacacia l.), which is a neophytic tree species widely distributed in europe. seventeen rhizobial strains isolated from nodules of black locust at a german location were examined by phenotypic characterization and 16s rdna analysis. the isolates were classified in nine 16s rdna genotypes using a set of seven endonucleases. based on rflp analysis and sequencing, the strains were shown to bel ... | 2000 | 11065378 |
| glutathione and homoglutathione synthetases of legume nodules. cloning, expression, and subcellular localization. | the thiol tripeptides glutathione (gsh) and homoglutathione (hgsh) are very abundant in legume root nodules and their synthesis is catalyzed by the enzymes gamma-glutamylcysteine synthetase (gammaecs), gsh synthetase (gshs), and hgsh synthetase (hgshs). as an essential step to elucidate the role of thiols in n(2) fixation we have isolated cdnas encoding the three enzymes and have quantified the transcripts in nodules. assay of enzyme activities in highly purified nodule organelles revealed that ... | 2000 | 11080313 |
| methylotrophic methylobacterium bacteria nodulate and fix nitrogen in symbiosis with legumes. | rhizobia described so far belong to three distinct phylogenetic branches within the alpha-2 subclass of proteobacteria. here we report the discovery of a fourth rhizobial branch involving bacteria of the methylobacterium genus. rhizobia isolated from crotalaria legumes were assigned to a new species, "methylobacterium nodulans," within the methylobacterium genus on the basis of 16s ribosomal dna analyses. we demonstrated that these rhizobia facultatively grow on methanol, which is a characterist ... | 2001 | 11114919 |
| a phaseolus vulgaris lipoxygenase gene expressed in nodules and in rhizobium tropici inoculated roots. | a genomic clone encoding a common bean lipoxygenase (pvlox5) was isolated from a phaseolus vulgaris library. reverse transcription-polymerase chain reaction analysis revealed that pvlox5 is expressed during nodule development and in rhizobium tropici inoculated roots. there was no detectable expression of pvlox5 in non-inoculated roots, healthy leaves, leaves after pseudomonas syringae pv. tabaci infection, floral buds or dry seeds. | 2000 | 11118627 |
| direct cloning from enrichment cultures, a reliable strategy for isolation of complete operons and genes from microbial consortia. | enrichment cultures of microbial consortia enable the diverse metabolic and catabolic activities of these populations to be studied on a molecular level and to be explored as potential sources for biotechnology processes. we have used a combined approach of enrichment culture and direct cloning to construct cosmid libraries with large (>30-kb) inserts from microbial consortia. enrichment cultures were inoculated with samples from five environments, and high amounts of avidin were added to the cu ... | 2001 | 11133432 |
| small-subunit rrna genotyping of rhizobia nodulating australian acacia spp. | the structure of rhizobial communities nodulating acacia in southeastern australia from south queensland to tasmania was investigated by a molecular approach. a total of 118 isolates from nodule samples from 13 different acacia species collected at 44 sites were characterized by small-subunit (ssu) ribosomal dna (rdna) pcr-restriction fragment length polymorphism analysis. nine rhizobial genomospecies were identified, and these taxa corresponded to previously described genomospecies (b. lafay an ... | 2001 | 11133471 |
| limited genetic diversity of brucella spp. | multilocus enzyme electrophoresis (mlee) of 99 brucella isolates, including the type strains from all recognized species, revealed a very limited genetic diversity and supports the proposal of a monospecific genus. in mlee-derived dendrograms, brucella abortus and a marine brucella sp. grouped into a single electrophoretic type related to brucella neotomae and brucella ovis. brucella suis and brucella canis formed another cluster linked to brucella melitensis and related to rhizobium tropici. th ... | 2001 | 11136777 |
| influence of tomato genotype on growth of inoculated and indigenous bacteria in the spermosphere. | we previously demonstrated a genetic basis in tomato for support of the growth of a biological control agent, bacillus cereus uw85, in the spermosphere after seed inoculation (k. p. smith, j. handelsman, and r. m. goodman, proc. natl. acad. sci. usa 96:4786-4790, 1999). here we report results of studies examining the host effect on the support of growth of bacillus and pseudomonas strains, both inoculated on seeds and recruited from soil, using selected inbred tomato lines from the recombinant i ... | 2001 | 11157211 |
| characterization of rhizobial isolates of phaseolus vulgaris by staircase electrophoresis of low-molecular-weight rna. | low-molecular-weight (lmw) rna molecules were analyzed to characterize rhizobial isolates that nodulate the common bean growing in spain. since lmw rna profiles, determined by staircase electrophoresis, varied across the rhizobial species nodulating beans, we demonstrated that bean isolates recovered from spanish soils presumptively could be characterized as rhizobium etli, rhizobium gallicum, rhizobium giardinii, rhizobium leguminosarum bv. viciae and bv. trifolii, and sinorhizobium fredii. | 2001 | 11157280 |
| enhanced symbiotic performance by rhizobium tropici glycogen synthase mutants. | we isolated a tn5-induced rhizobium tropici mutant that has enhanced capacity to oxidize n,n-dimethyl-p-phenylendiamine (dmpd) and therefore has enhanced respiration via cytochrome oxidase. the mutant had increased levels of the cytochromes c(1) and cycm and a small increase in the amount of cytochrome aa(3). in plant tests, the mutant increased the dry weight of phaseolus vulgaris plants by 20 to 38% compared with the control strain, thus showing significantly enhanced symbiotic performance. th ... | 2001 | 11208782 |
| p(ii) signal transduction proteins, pivotal players in microbial nitrogen control. | the p(ii) family of signal transduction proteins are among the most widely distributed signal proteins in the bacterial world. first identified in 1969 as a component of the glutamine synthetase regulatory apparatus, p(ii) proteins have since been recognized as playing a pivotal role in control of prokaryotic nitrogen metabolism. more recently, members of the family have been found in higher plants, where they also potentially play a role in nitrogen control. the p(ii) proteins can function in t ... | 2001 | 11238986 |
| a functional myo-inositol dehydrogenase gene is required for efficient nitrogen fixation and competitiveness of sinorhizobium fredii usda191 to nodulate soybean (glycine max [l.] merr.). | inositol derivative compounds provide a nutrient source for soil bacteria that possess the ability to degrade such compounds. rhizobium strains that are capable of utilizing certain inositol derivatives are better colonizers of their host plants. we have cloned and determined the nucleotide sequence of the myo-inositol dehydrogenase gene (idha) of sinorhizobium fredii usda191, the first enzyme responsible for inositol catabolism. the deduced idha protein has a molecular mass of 34,648 da and sho ... | 2001 | 11274120 |
| rhizobial nodl o-acetyl transferase and nods n-methyl transferase functionally interfere in production of modified nod factors. | the products of the rhizobial nodulation genes are involved in the biosynthesis of lipochitin oligosaccharides (lcos), which are host-specific signal molecules required for nodule formation. the presence of an o-acetyl group on c-6 of the nonreducing n-acetylglucosamine residue of lcos is due to the enzymatic activity of nodl. here we show that transfer of the nodl gene into four rhizobial species that all normally produce lcos that are not modified on c-6 of the nonreducing terminal residue res ... | 2001 | 11344149 |
| unusual methyl-branched alpha,beta-unsaturated acyl chain substitutions in the nod factors of an arctic rhizobium, mesorhizobium sp. strain n33 (oxytropis arctobia). | mesorhizobium sp. strain n33 (oxytropis arctobia), a rhizobial strain isolated in arctic canada, is able to fix nitrogen at very low temperatures in association with a few arctic legume species belonging to the genera astragalus, onobrychis, and oxytropis. using mass spectrometry and nuclear magnetic resonance spectroscopy, we have determined the structure of n33 nod factors, which are major determinants of nodulation. they are pentameric lipochito-oligosaccharides 6-o sulfated at the reducing e ... | 2001 | 11371536 |
| nitrate reductase activity, distribution, and response to nitrate in two contrasting phaseolus species inoculated with rhizobium spp. | the nitrate reductase activity distribution and response of two nodulated species of phaseolus (phaseolus vulgaris-common bean, and phaseolus lunatus-lima bean) to different exogenous nitrate levels were studied during the vegetative period. these phaseolus species showed to be very contrasting in respect to the pattern of nitrate reductase (nr) activity distribution thought the plant. the highest level of nr activity in p. vulgaris was clearly shown to occur in leaves in contrast with the lowes ... | 2001 | 11378171 |
| periplasmic pqq-dependent glucose oxidation in free-living and symbiotic rhizobia. | the expression of the pyrroloquinoline quinone (pqq)-dependent glucose dehydrogenase (gdh) of rhizobium tropici ciat899 and sinorhizobium meliloti rcr2011 was investigated under different nutrient-limiting conditions in continuous cultures, under different conditions of phosphate availability, and in s. meliloti bacteroids. the presence of free pqq in alfalfa root exudates has also been assayed. it was shown that apo-gdh or holoenzyme was actively synthesized by these rhizobia, with the concomit ... | 2001 | 11400050 |
| nitrogen-fixing nodules with ensifer adhaerens harboring rhizobium tropici symbiotic plasmids. | ensifer adhaerens is a soil bacterium that attaches to other bacteria and may cause lysis of these other bacteria. based on the sequence of its small-subunit rrna gene, e. adhaerens is related to sinorhizobium spp. e. adhaerens atcc 33499 did not nodulate phaseolus vulgaris (bean) or leucaena leucocephala, but with symbiotic plasmids from rhizobium tropici cfn299 it formed nitrogen-fixing nodules on both hosts. the nodule isolates were identified as e. adhaerens isolates by growth on selective m ... | 2001 | 11425750 |