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phylogeny of fast-growing soybean-nodulating rhizobia support synonymy of sinorhizobium and rhizobium and assignment to rhizobium fredii.we determined the sequences for a 260-base segment amplified by the polymerase chain reaction (corresponding to positions 44 to 337 in the escherichia coli 16s rrna sequence) from seven strains of fast-growing soybean-nodulating rhizobia (including the type strains of rhizobium fredii chemovar fredii, rhizobium fredii chemovar siensis, sinorhizobium fredii, and sinorhizobium xinjiangensis) and broad-host-range rhizobium sp. strain ngr 234. these sequences were compared with the corresponding pre ...19921371066
hyperreiterated dna regions are conserved among bradyrhizobium japonicum serocluster 123 strains.we have identified and cloned two dna regions which are highly reiterated in bradyrhizobium japonicum serocluster 123 strains. while one of the reiterated dna regions, pfr2503, is closely linked to the b. japonicum common and genotype-specific nodulation genes in strain usda 424, the other, pmap9, is located next to a tn5 insertion site in a host-range extension mutant of b. japonicum usda 438. the dna cloned in pfr2503 and pmap9 are reiterated 18 to 21 times, respectively, in the genomes of b. ...19921622264
occurrence of lipid a variants with 27-hydroxyoctacosanoic acid in lipopolysaccharides from members of the family rhizobiaceae.lipopolysaccharides (lpss) isolated from several strains of rhizobium, bradyrhizobium, agrobacterium, and azorhizobium were screened for the presence of 27-hydroxyoctacosanoic acid. the lpss from all strains, with the exception of azorhizobium caulinodans, contained various amounts of this long-chain hydroxy fatty acid in the lipid a fractions. analysis of the lipid a sugars revealed three types of backbones: those containing glucosamine (as found in rhizobium meliloti and rhizobium fredii), tho ...19912007543
isoflavonoid-inducible resistance to the phytoalexin glyceollin in soybean rhizobia.the antibacterial effect of the soybean phytoalexin glyceollin was assayed using a liquid microculture technique. log-phase cells of bradyrhizobium japonicum and sinorhizobium fredii were sensitive to glyceollin. as revealed by growth rates and survival tests, these species were able to tolerate glyceollin after adaptation. incubation in low concentrations of the isoflavones genistein and daidzein induced resistance to potentially bactericidal concentrations of glyceollin. this inducible resista ...19912045365
two host-inducible genes of rhizobium fredii and characterization of the inducing compound.random transcription fusions with mu d1(kan lac) generated three mutants in rhizobium fredii (strain usda 201) which showed induction of beta-galactosidase when grown in root exudate of the host plants glycine max, phaseolus vulgaris, and vigna ungliculata. two genes were isolated from a library of total plasmid dna of one of the mutants, 3f1. these genes, present in tandem on a 4.2-kilobase hindiii fragment, appear in one copy each on the symbiotic plasmid and do not hybridize to the rhizobium ...19882447061
influence of soil variables on in situ plasmid transfer from escherichia coli to rhizobium fredii.a model system was established to determine whether intergeneric plasmid transfer occurs in soil and how various soil variables affect the rate of plasmid transfer. the donor bacterium, escherichia coli hb101 carrying plasmid pblk1-2 (prk2073::tn5), and the recipient bacterium, rhizobium fredii usda 201, were inoculated into a sterile adelphia fine-sandy-loam soil. transconjugants were enumerated by direct plating on antibiotic-amended hm [n-2-hydroxyethylpiperazine-n'-2-ethanesulfonic acid; 2-( ...19892669634
evidence for plasmid- and chromosome-borne multiple nif genes in rhizobium fredii.rhizobium fredii is a fast-growing rhizobium isolated from the primitive chinese soybean cultivar peking and from the wild soybean glycine soja. this rhizobium harbors nif genes on 150- to 200-megadalton plasmids. by passage on acridine orange plates, we obtained a mutant of r. fredii usda 206 cured of the 197-megadalton plasmid (usda 206c) which carries both nif and nod genes. this strain, however, has retained its symbiotic effectiveness. probing ecori digests of wild-type and cured plasmid dn ...19852992376
isolation and characterization of the dna region encoding nodulation functions in bradyrhizobium japonicum.the dna region encoding early nodulation functions of bradyrhizobium japonicum 3i1b110 (i110) was isolated by its homology to the functionally similar region from rhizobium meliloti. isolation of a number of overlapping recombinant clones from this region allowed the construction of a restriction map of the region. the identified nodulation region of b. japonicum shows homology exclusively to those regions of r. meliloti and rhizobium leguminosarum dna known to encode early nodulation functions. ...19852999080
mobilization of tn5 insertions from rhizobium fredii by pjb3ji.techniques for in vivo cloning were used with the fast-growing nitrogen-fixing soybean microsymbiont r. fredii usda 191. selection for transfer of tn5 insertions from r. fredii usda 191 containing the gene-mobilizing plasmid pjb3ji provided recombinants at up to 400 times the background mutation level. these techniques may be useful for future genetic analysis of r. fredii.19863015025
isolation of competition-defective mutants of rhizobium fredii.we coupled tn5 mutagenesis with a competition assay to isolate mutants of rhizobium fredii usda 257 that are defective in competition for nodulation of soybeans. two mutants with single tn5 inserts in the chromosome showed reduced competitiveness in vermiculite but were identical to the wild-type strain in symbiotic properties when inoculated alone. recombination of tn5 and flanking genomic regions cloned from the mutants into the parent strain showed that tn5 was responsible for the mutant phen ...19873025184
molecular cloning and expression of rhizobium fredii usda 193 nodulation genes: extension of host range for nodulation.dna hybridization with the cloned nodulation region of rhizobium meliloti as a probe revealed dna homology with four hindiii fragments, 12.5, 6.8, 5.2, and 0.3 kilobases (kb) in size, of the symbiotic plasmid prjausda193. both hybridization and complementation studies suggest that the common nodulation genes nodabc and nodd of r. fredii usda 193 are present on the 5.2-kb hindiii and 2.8-kb ecori fragments, respectively, of the sym plasmid. both fragments together could confer nodulation ability ...19863782034
enzymes of the beta-ketoadipate pathway are inducible in rhizobium and agrobacterium spp. and constitutive in bradyrhizobium spp.protocatechuate is a universal growth substrate for members of the family rhizobiaceae, and these bacteria utilize the aromatic compound via the beta-ketoadipate pathway. this report describes transcriptional controls exercised by different subgroups of the rhizobiaceae over five enzymes that catalyze consecutive reactions in the pathway: protocatechuate oxygenase (ec 1.13.11.3), beta-carboxy-cis,cis-muconate lactonizing enzyme (ec 5.5.1.2), gamma-carboxymuconolactone decarboxylase (ec 4.1.1.44) ...19863941043
suppression of the fix- phenotype of rhizobium meliloti exob mutants by lpsz is correlated to a modified expression of the k polysaccharide.the rhizobial production of extracellular polysaccharide (eps) is generally required for the symbiotic infection of host plants that form nodules with an apical meristem (indeterminate nodules). one exception is rhizobium meliloti ak631, an exob mutant of rm41, which is deficient in eps production yet infects and fixes nitrogen (i.e., is fix+) on alfalfa, an indeterminate nodule-forming plant. a mutation of lpsz in ak631 results in a fix- strain with altered phage sensitivity, suggesting that a ...19957635814
rhizobia catabolize nod gene-inducing flavonoids via c-ring fission mechanisms.gas chromatographic and mass spectrometric analyses of derivatized culture medium extracts were used to identify the products of flavonoid metabolism by rhizobia. a number of rhizobium species and biovars degraded their nod gene-inducing flavonoids by mechanisms which originated in a cleavage of the c-ring of the molecule and which yielded conserved a- and b-ring products among the metabolites. in contrast, pseudomonas putida degraded quercetin via an initial fission in its a-ring, and agrobacte ...19948071218
infection of soybean and pea nodules by rhizobium spp. purine auxotrophs in the presence of 5-aminoimidazole-4-carboxamide riboside.purine auxotrophs of various rhizobium species are symbiotically defective, usually unable to initiate or complete the infection process. earlier studies demonstrated that, in the rhizobium etli-bean symbiosis, infection by purine auxotrophs is partially restored by supplementation of the plant medium with 5-amino-imidazole-4-carboxamide (aica) riboside, the unphosphorylated form of the purine biosynthetic intermediate aicar. the addition of purine to the root environment does not have this effe ...19948195084
characterization of rfrs9, a second member of the rhizobium fredii repetitive sequence family from the nitrogen-fixing symbiont r. fredii usda257.the genome of the nitrogen-fixing symbiont, rhizobium fredii usda257, contains nine copies of repetitive sequences known as the r. fredii repetitive sequence (rfrs) family. we previously sequenced rfrs3, which is linked to symbiosis plasmid-borne nodulation genes of this organism and has substantial homology to the t-dna of agrobacterium rhizogenes and lesser homology to reiterated sequences of bradyrhizobium japonicum. here we characterize a second family member, rfrs9. the ecori fragment conta ...19938382462
rhizobium fredii and rhizobium meliloti produce 3-deoxy-d-manno-2-octulosonic acid-containing polysaccharides that are structurally analogous to group ii k antigens (capsular polysaccharides) found in escherichia coli.the polysaccharide components from cultured cells of rhizobium fredii usda205 and rhizobium meliloti ak631 were extracted with hot phenol-water and separated by repetitive gel filtration chromatography. polyacrylamide gel electrophoresis, nuclear magnetic resonance spectrometry, and gas chromatography analyses showed that both of these bacterial species produce unique polysaccharides that contain a high proportion of 3-deoxy-d-manno-2-octulosonic acid (kdo). these polysaccharides, which constitu ...19938501061
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 ...19968655573
sinorhizobium medicae sp. nov., isolated from annual medicago spp.the taxonomic position of isolates of a new genomic species (designated genomic species 2) obtained from several annual medicago species and originating from different geographical locations was established through the results of phenotypic tests (including the results of auxanographic and biochemical tests and symbiotic properties) and 16s rrna phylogenetic inferences. a comparison of the complete 16s rrna sequence of a representative of genomic species 2 (strain a 321t [t = type strain]) with ...19968863426
the soybean cultivar specificity gene nolx is present, expressed in a nodd-dependent manner, and of symbiotic significance in cultivar-nonspecific strains of rhizobium (sinorhizobium) fredii.rhizobium (now sinorhizobium) fredii is a symbiotic nitrogen-fixing bacterium that can nodulate soybean in a cultivar-specific manner. this process is governed by a set of negatively acting nodulation genes termed nolxwbtuv. these genes prevent r. fredii strain usda257 from infecting soybean cultivars such as mccall, but they do not block nodulation of cultivar peking. r. fredii strain usda191 contains dna sequences that hybridize to nolxwbtuv, yet it forms normal nitrogen-fixing nodules on both ...19979141700
structural characterization of the k antigens from rhizobium fredii usda257: evidence for a common structural motif, with strain-specific variation, in the capsular polysaccharides of rhizobium spp.rhizobium fredii participates in a nitrogen-fixing symbiosis with soybeans, in a strain-cultivar-specific interaction, and past studies have shown that the cell surface and extracellular polysaccharides of rhizobia function in the infection process that leads to symbiosis. the structural analysis of the capsular polysaccharides (k antigens) from strain usda257 was performed in this study. the k antigens were extracted from cultured cells with hot phenol-water and purified by size exclusion chrom ...19979286989
rapid identification of medicago nodulating strains by using two oligonucleotide probes complementary to 16s rdna sequences.symbiotic bacteria associated with the medicago genus are separated into two closely related species named sinorhizobium meliloti and sinorhizobium medicae. to discriminate rapidly between these two bacterial species, two 15-base dna probes, 16smfs and 16smed, were designed from the alignment of 16s rdna sequences to differentiate s. meliloti from s. medicae. their specificities were evaluated by dot-blot hybridization experiments on 25 reference strains representing 13 species of rhizobium and ...19979336948
isrf1, a transposable insertion sequence from sinorhizobium fredii.sinorhizobium fredii strain hh103, a nitrogen-fixing bacterial symbiont of plants, contains an insertion sequence (is) that can transpose into plasmid pmus248 and activate a promoterless tcr gene that is normally not expressed. we have cloned and characterized this element, which we designate isrf1. the is is 1002 bp in length, contains a single 513-bp open reading frame (orf), is flanked by imperfect 36-bp terminal inverted repeats, and creates 5-bp target duplications. two copies of isrf1 are ...19979434166
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 ...19989464375
exopolysaccharide ii production is regulated by salt in the halotolerant strain rhizobium meliloti efb1.the halotolerant strain rhizobium meliloti efb1 modifies the production of extracellular polysaccharides in response to salt. efb1 colonies grown in the presence of 0.3 m nacl show a decrease in mucoidy, and in salt-supplemented liquid medium this organism produces 40% less exopolysaccharides. we isolated transposon-induced mutant that, when grown in the absence of salt, had a colony morphology (nonmucoid) similar to the colony morphology of the wild type grown in the presence of salt. calcofluo ...19989501442
characterization of rhizobium leguminosarum exopolysaccharide glycanases that are secreted via a type i exporter and have a novel heptapeptide repeat motif.the prsde genes encode a type i protein secretion system required for the secretion of the nodulation protein nodo and at least three other proteins from rhizobium leguminosarum bv. viciae. at least one of these proteins was predicted to be a glycanase involved in processing of bacterial exopolysaccharide (eps). two strongly homologous genes (plya and plyb) were identified as encoding secreted proteins with polysaccharide degradation activity. both plya and plyb degrade eps and carboxymethyl cel ...19989537364
unconventional genomic organization in the alpha subgroup of the proteobacteria.pulsed-field gel electrophoresis was used to analyze the genomic organization of 16 bacteria belonging or related to the family rhizobiaceae of the alpha subgroup of the class proteobacteria. the number and sizes of replicons were determined by separating nondigested dna. hybridization of an rrn gene probe was used to distinguish between chromosomes and plasmids. members of the genus agrobacterium all possess two chromosomes, and each biovar has a specific genome size. as previously demonstrated ...19989573163
the atzabc genes encoding atrazine catabolism are located on a self-transmissible plasmid in pseudomonas sp. strain adp.pseudomonas sp. strain adp initiates atrazine catabolism via three enzymatic steps, encoded by atza, -b, and -c, which yield cyanuric acid, a nitrogen source for many bacteria. in-well lysis, southern hybridization, and plasmid transfer studies indicated that the atza, -b, and -c genes are localized on a 96-kb self-transmissible plasmid, padp-1, in pseudomonas sp. strain adp. high-performance liquid chromatography analyses showed that cyanuric acid degradation was not encoded by padp-1. padp-1 w ...19989603862
type iii protein secretion systems in bacterial pathogens of animals and plants.various gram-negative animal and plant pathogens use a novel, sec-independent protein secretion system as a basic virulence mechanism. it is becoming increasingly clear that these so-called type iii secretion systems inject (translocate) proteins into the cytosol of eukaryotic cells, where the translocated proteins facilitate bacterial pathogenesis by specifically interfering with host cell signal transduction and other cellular processes. accordingly, some type iii secretion systems are activat ...19989618447
release of flavonoids by the soybean cultivars mccall and peking and their perception as signals by the nitrogen-fixing symbiont sinorhizobium frediisinorhizobium fredii strain usda191 forms n-fixing nodules on the soybean (glycine max l. merr.) cultivars (cvs) mccall and peking, but s. fredii strain usda257 nodulates only cv peking. we wondered whether specificity in this system is conditioned by the release of unique flavonoid signals from one of the cultivars or by differential perception of signals by the strains. we isolated flavonoids and used nodc and nolx, which are nod-box-dependent and -independent nod genes, respectively, to deter ...19989625713
differential regulation of rhizobium etli rpon2 gene expression during symbiosis and free-living growth.the rhizobium etli rpon1 gene, encoding the alternative sigma factor sigma54 (rpon), was recently characterized and shown to be involved in the assimilation of several nitrogen and carbon sources during free-living aerobic growth (j. michiels, t. van soom, i. d'hooghe, b. dombrecht, t. benhassine, p. de wilde, and j. vanderleyden, j. bacteriol. 180:1729-1740, 1998). we identified a second rpon gene copy in r. etli, rpon2, encoding a 54.0-kda protein which displays 59% amino acid identity with th ...19989658006
genetic characterization of a mutant of sinorhizobium fredii strain usda208 with enhanced competitive ability for nodulation of soybean, glycine max (l.) merr.sinorhizobium fredii strain usda208 is a nitrogen-fixing bacterium that forms nodules on roots of soybean and other legume plants. we previously found that the tn5-containing mutant 208t3, which was derived from strain usda208, is both deficient in production of exopolysaccharides and more competitive than the wild-type strain in competing against other rhizobia for nodulation of soybean. we now demonstrate that the transposon insertion of the mutant lies in a locus that is highly homologous to ...19989711859
characterization of the hrpc and hrprs operons of pseudomonas syringae pathovars syringae, tomato, and glycinea and analysis of the ability of hrpf, hrpg, hrcc, hrpt, and hrpv mutants to elicit the hypersensitive response and disease in plants.the species pseudomonas syringae encompasses plant pathogens with differing host specificities and corresponding pathovar designations. p. syringae requires the hrp (type iii protein secretion) system, encoded by a 25-kb cluster of hrp and hrc genes, in order to elicit the hypersensitive response (hr) in nonhosts or to be pathogenic in hosts. dna sequence analysis of the hrpc and hrprs operons of p. syringae pv. syringae 61 (brown spot of beans), p. syringae pv. glycinea u1 (bacterial blight of ...19989721291
characterization of a novel acyl carrier protein, rkpf, encoded by an operon involved in capsular polysaccharide biosynthesis in sinorhizobium meliloti.rhizobial capsular polysaccharides (rkps) play an important role in the development of a nitrogen-fixing symbiosis with the plant host and in sinorhizobium meliloti ak631 functional rkpabcdef genes are required for the production of rkps. after cloning the rkpf gene, we overexpressed and purified the derived protein product (rkpf) in escherichia coli. like acyl carrier protein (acp), the rkpf protein can be labeled in vivo with radioactive beta-alanine added to the growth medium. if homogeneous ...19989733701
novel rkp gene clusters of sinorhizobium meliloti involved in capsular polysaccharide production and invasion of the symbiotic nodule: the rkpk gene encodes a udp-glucose dehydrogenase.the production of exopolysaccharide (eps) was shown to be required for the infection process by rhizobia that induce the formation of indeterminate nodules on the roots of leguminous host plants. in sinorhizobium meliloti (also known as rhizobium meliloti) rm41, a capsular polysaccharide (kps) analogous to the group ii k antigens of escherichia coli can replace eps during symbiotic nodule development and serve as an attachment site for the strain-specific bacteriophage phi16-3. the rkpa to -j ge ...19989765575
different phenotypic classes of sinorhizobium meliloti mutants defective in synthesis of k antigen.for sinorhizobium meliloti (also known as rhizobium meliloti) ak631 to establish effective symbiosis with alfalfa, it must be able to synthesize a symbiotically active form of its k antigen, a capsular polysaccharide containing a kdo (3-deoxy-d-manno-octulosonic acid) derivative. previously isolated mutants defective in the synthesis of k antigen are resistant to bacteriophage phi16-3. by screening ca. 100,000 tn5-mutagenized r. meliloti bacteria for resistance to bacteriophage phi16-3, we isola ...19989765576
genetic diversity and phylogeny of rhizobia that nodulate acacia spp. in morocco assessed by analysis of rrna genesforty 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 ...19989835582
sinorhizobium fredii and sinorhizobium meliloti produce structurally conserved lipopolysaccharides and strain-specific k antigens.lipopolysaccharides (lps) and capsular polysaccharides (k antigens) may influence the interaction of rhizobia with their specific hosts; therefore, we conducted a comparative analysis of sinorhizobium fredii and sinorhizobium meliloti, which are genetically related, yet symbiotically distinct, nitrogen-fixing microsymbionts of legumes. we found that both species typically produce strain-specific k antigens that consist of 3-deoxy-d-manno-2-octulosonic acid (kdo), or other 1-carboxy-2-keto-3-deox ...19989835585
the virulence plasmid of yersinia, an antihost genome.the 70-kb virulence plasmid enables yersinia spp. (yersinia pestis, y. pseudotuberculosis, and y. enterocolitica) to survive and multiply in the lymphoid tissues of their host. it encodes the yop virulon, an integrated system allowing extracellular bacteria to disarm the cells involved in the immune response, to disrupt their communications, or even to induce their apoptosis by the injection of bacterial effector proteins. this system consists of the yop proteins and their dedicated type iii sec ...19989841674
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 ...19999922261
a 55-kilodalton immunodominant antigen of porphyromonas gingivalis w50 has arisen via horizontal gene transfer.a 55-kda outer membrane protein of porphyromonas gingivalis w50 is a significant target of the serum immunoglobulin g antibody response of periodontal disease patients and hence may play an important role in host-bacterium interactions in periodontal disease. the gene encoding the 55-kda antigen (ragb, for receptor antigen b) was isolated on a 9.5-kb partial sau3ai fragment of p. gingivalis w50 chromosomal dna in puc18 by immunoscreening with a monoclonal antibody to this antigen. the 1.6-kb ope ...199910024556
the bradyrhizobium japonicum nola gene encodes three functionally distinct proteins.examination of nola revealed that nola can be uniquely translated from three atg start codons. translation from the first atg (atg1) predicts a protein (nola1) having an n-terminal, helix-turn-helix dna-binding motif similar to the dna-binding domains of the merr-type regulatory proteins. translation from atg2 and atg3 would give the n-terminally truncated proteins nola2 and nola3, respectively, lacking the dna-binding domain. consistent with this, immunoblot analyses of bradyrhizobium japonicum ...199910049387
polynucleotide probes that target a hypervariable region of 16s rrna genes to identify bacterial isolates corresponding to bands of community fingerprints.temperature gradient gel electrophoresis (tgge) is well suited for fingerprinting bacterial communities by separating pcr-amplified fragments of 16s rrna genes (16s ribosomal dna [rdna]). a strategy was developed and was generally applicable for linking 16s rdna from community fingerprints to pure culture isolates from the same habitat. for this, digoxigenin-labeled polynucleotide probes were generated by pcr, using bands excised from tgge community fingerprints as a template, and applied in hyb ...199910049861
disaccharides as a new class of nonaccumulated osmoprotectants for sinorhizobium meliloti.sucrose and ectoine (1,4,5,6-tetrahydro-2-methyl-4-pyrimidine carboxylic acid) are very unusual osmoprotectants for sinorhizobium meliloti because these compounds, unlike other bacterial osmoprotectants, do not accumulate as cytosolic osmolytes in salt-stressed s. meliloti cells. here, we show that, in fact, sucrose and ectoine belong to a new family of nonaccumulated sinorhizobial osmoprotectants which also comprises the following six disaccharides: trehalose, maltose, cellobiose, gentiobiose, ...199910103242
the periplasmic nitrate reductase in pseudomonas sp. strain g-179 catalyzes the first step of denitrification.both membrane-bound and periplasmic nitrate reductases have been found in denitrifying bacteria. yet the role of periplasmic nitrate reductase in denitrification has not been clearly defined. to analyze the function of the periplasmic nitrate reductase in pseudomonas sp. strain g-179, the nap gene cluster was identified and found to be linked to genes involved in reduction of nitrite and nitric oxide and anaerobic heme biosynthesis. mutation in the nap region rendered the cells incapable of grow ...199910217771
occurrence of choline and glycine betaine uptake and metabolism in the family rhizobiaceae and their roles in osmoprotectionthe 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 ...199910224003
purification and characterization of an alpha-glucosidase from rhizobium sp. (robinia pseudoacacia l.) strain usda 4280.a novel alpha-glucosidase with an apparent subunit mass of 59 +/- 0. 5 kda was purified from protein extracts of rhizobium sp. strain usda 4280, a nodulating strain of black locust (robinia pseudoacacia l), and characterized. after purification to homogeneity (475-fold; yield, 18%) by ammonium sulfate precipitation, cation-exchange chromatography, hydrophobic chromatography, dye chromatography, and gel filtration, this enzyme had a pi of 4.75 +/- 0.05. the enzyme activity was optimal at ph 6.0 t ...199910388682
the 102-kilobase pgm locus of yersinia pestis: sequence analysis and comparison of selected regions among different yersinia pestis and yersinia pseudotuberculosis strains.we report the complete 119,443-bp sequence of the pgm locus from yersinia pestis and its flanking regions. sequence analysis confirms that the 102-kb unstable pgm locus is composed of two distinct parts: the pigmentation segment and a high-pathogenicity island (hpi) which carries virulence genes involved in iron acquisition (yersiniabactin biosynthetic gene cluster). within the hpi, three genes coding for proteins related to phage proteins were uncovered. they are located at both extremities ind ...199910456941
reduction of adenosine-5'-phosphosulfate instead of 3'-phosphoadenosine-5'-phosphosulfate in cysteine biosynthesis by rhizobium meliloti and other members of the family rhizobiaceae.we have cloned and sequenced three genes from rhizobium meliloti (sinorhizobium meliloti) that are involved in sulfate activation for cysteine biosynthesis. two of the genes display homology to the escherichia coli cysdn genes, which code for an atp sulfurylase (ec 2.7.7.4). the third gene has homology to the e. coli cysh gene, a 3'-phosphoadenosine-5'-phosphosulfate (paps) reductase (ec 1.8.99.4), but has greater homology to a set of genes found in arabidopsis thaliana that encode an adenosine- ...199910464198
development and application of pathovar-specific monoclonal antibodies that recognize the lipopolysaccharide o antigen and the type iv fimbriae of xanthomonas hyacinthi.the objective of this study was to develop a specific immunological diagnostic assay for yellow disease in hyacinths, using monoclonal antibodies (mabs). mice were immunized with a crude cell wall preparation (shear fraction) from xanthomonas hyacinthi and with purified type iv fimbriae. hybridomas were screened for a positive reaction with x. hyacinthi cells or fimbriae and for a negative reaction with x. translucens pv. graminis or erwinia carotovora subsp. carotovora. nine mabs recognized fim ...199910473431
halomethane:bisulfide/halide ion methyltransferase, an unusual corrinoid enzyme of environmental significance isolated from an aerobic methylotroph using chloromethane as the sole carbon source.a novel dehalogenating/transhalogenating enzyme, halomethane:bisulfide/halide ion methyltransferase, has been isolated from the facultatively methylotrophic bacterium strain cc495, which uses chloromethane (ch(3)cl) as the sole carbon source. purification of the enzyme to homogeneity was achieved in high yield by anion-exchange chromatography and gel filtration. the methyltransferase was composed of a 67-kda protein with a corrinoid-bound cobalt atom. the purified enzyme was inactive but was act ...199910508052
epitope identification for a panel of anti-sinorhizobium meliloti monoclonal antibodies and application to the analysis of k antigens and lipopolysaccharides from bacteroids.in two published reports using monoclonal antibodies (mabs) generated against whole cells, olsen et al. showed that strain-specific antigens on the surface of cultured cells of sinorhizobium meliloti were diminished or absent in the endophytic cells (bacteroids) recovered from alfalfa nodules, whereas two common antigens were not affected by bacterial differentiation (p. olsen, m. collins, and w. rice, can. j. microbiol. 38:506-509, 1992; p. olsen, s. wright, m. collins, and w. rice, appl. envir ...199910543844
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 ...200010618208
environmental regulation of exopolysaccharide production in sinorhizobium meliloti.exopolysaccharide production by sinorhizobium meliloti is required for invasion of root nodules on alfalfa and successful establishment of a nitrogen-fixing symbiosis between the two partners. s. meliloti wild-type strain rm1021 requires production of either succinoglycan, a polymer of repeating octasaccharide subunits, or eps ii, an exopolysaccharide of repeating dimer subunits. the reason for the production of two functional exopolysaccharides is not clear. earlier reports suggested that low-p ...200010633091
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- ...200010704479
identification of two novel hrp-associated genes in the hrp gene cluster of xanthomonas oryzae pv. oryzae.we have cloned a hrp gene cluster from xanthomonas oryzae pv. oryzae. bacteria with mutations in the hrp region have reduced growth in rice leaves and lose the ability to elicit a hypersensitive response (hr) on the appropriate resistant cultivars of rice and the nonhost plant tomato. a 12,165-bp portion of nucleotide sequence from the presumed left end and extending through the hrpb operon was determined. the region was most similar to hrp genes from xanthomonas campestris pv. vesicatoria and r ...200010714988
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 ...200010758890
the ++sinorhizobium meliloti lon protease is involved in regulating exopolysaccharide synthesis and is required for nodulation of alfalfa.while screening for sinorhizobium meliloti pho regulatory mutants, a transposon mutant was isolated that constitutively expressed higher levels of acid and alkaline phosphatase enzymes. this mutant was also found to form pseudonodules on alfalfa that were delayed in appearance relative to those formed by the wild-type strain, it contained few bacteroids, and it did not fix nitrogen. sequence analysis of the transposon insertion site revealed the affected gene to have high homology to lon proteas ...200010762258
genome structure of the genus azospirillum.azospirillum species are plant-associated diazotrophs of the alpha subclass of proteobacteria. the genomes of five of the six azospirillum species were analyzed by pulsed-field gel electrophoresis. all strains possessed several megareplicons, some probably linear, and 16s ribosomal dna hybridization indicated multiple chromosomes in genomes ranging in size from 4.8 to 9.7 mbp. the nifhdk operon was identified in the largest replicon.200010869094
isolation and characterization of 2,3-dichloro-1-propanol-degrading rhizobia.2,3-dichloro-1-propanol is more chemically stable than its isomer, 1, 3-dichloro-2-propanol, and is therefore more difficult to degrade. the isolation of bacteria capable of complete mineralization of 2, 3-dichloro-1-propanol was successful only from enrichments at high ph. the bacteria thus isolated were found to be members of the alpha division of the proteobacteria in the rhizobium subdivision, most likely agrobacterium sp. they could utilize both dihaloalcohol substrates and 2-chloropropioni ...200010877782
alfalfa root nodule invasion efficiency is dependent on sinorhizobium meliloti polysaccharides.the soil bacterium sinorhizobium meliloti is capable of entering into a nitrogen-fixing symbiosis with medicago sativa (alfalfa). particular low-molecular-weight forms of certain polysaccharides produced by s. meliloti are crucial for establishing this symbiosis. alfalfa nodule invasion by s. meliloti can be mediated by any one of three symbiotically important polysaccharides: succinoglycan, eps ii, or k antigen (also referred to as kps). using green fluorescent protein-labeled s. meliloti cells ...200010894742
pcr use of highly conserved dna regions for identification of sinorhizobium meliloti.a pcr identification method in which four primers that recognize homologous conserved regions in the sinorhizobium meliloti genome are used was developed and tested. the regions used for identification were the nodbox 4 locus, which is located in one of the symbiotic megaplasmids, and the mucr gene, which is located in the chromosome. the new method was used to establish a collection of s. meliloti strains from polluted soils.200010919829
rnase iii processing of intervening sequences found in helix 9 of 23s rrna in the alpha subclass of proteobacteria.we provide experimental evidence for rnase iii-dependent processing in helix 9 of the 23s rrna as a general feature of many species in the alpha subclass of proteobacteria (alpha-proteobacteria). we investigated 12 rhodobacter, rhizobium, sinorhizobium, rhodopseudomonas, and bartonella strains. the processed region is characterized by the presence of intervening sequences (ivss). the 23s rdna sequences between positions 109 and 205 (escherichia coli numbering) were determined, and potential seco ...200010940010
sinorhizobium fredii usda257, a cultivar-specific soybean symbiont, carries two copies of y4ya and y4yb, two open reading frames that are located in a region that encodes the type iii protein secretion system.sinorhizobium fredii usda257 forms nitrogen-fixing nodules on primitive soybean (glycine max) cultivar peking but fails to nodulate the improved cultivar mccall. cultivar specificity is governed by a plasmid-borne locus, nolxbtuv. by dna sequence analysis, we have identified two open reading frames, y4ya and y4yb, immediately downstream of nolx. northern (rna) blot analysis indicated that the expression of both y4ya and y4yb is inducible by isoflavonoids, and an intact copy of nolx is required. ...200010975657
the lipid a region of lipopolysaccharides from rhizobiaceae activates bone marrow granulocytes from lipopolysaccharide-hyporesponsive c3h/hej and c57bl/10sccr mice.we established in previous studies that the binding of salmonella lipopolysaccharide (lps) to constitutive receptors of low affinity triggers the expression of the inducible lps-binding molecule cd14 in bone marrow cells (bmc) of c3h/heou mice, but not in bmc from c3h/hej mice. we show in this study that bmc from c3h/hej and c57bl/10sccr mice do not express cd14 after exposure to lpss from salmonella enterica and bordetella pertussis, but do express this marker when treated with several lpss fro ...200011012780
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 ...200011055970
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 ...200111114919
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.200111157280
genetic characterization of a sinorhizobium meliloti chromosomal region in lipopolysaccharide biosynthesis.the genetic characterization of a 5.5-kb chromosomal region of sinorhizobium meliloti 2011 that contains lpsb, a gene required for the normal development of symbiosis with medicago spp., is presented. the nucleotide sequence of this dna fragment revealed the presence of six genes: grea and lpsb, transcribed in the forward direction; and lpse, lpsd, lpsc, and lrp, transcribed in the reverse direction. except for lpsb, none of the lps genes were relevant for nodulation and nitrogen fixation. analy ...200111157937
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 ...200111344149
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 ...200111425750
[cloning of gene related to salt tolerance from sinorhizobium fredii rt19 and its expression in escherichia coli].a 4.4 kb dna fragment related to salt tolerance containing three open reading frames was isolated from the gene library of s. fredii strain rt19. by subcloning and functional analysis, only orf2 related to salt tolerance was obtained. the orf2 was ligated to expression vectors pthiohisa, b and c, respectively, and recombinant expression vectors pga, pgb and pgc containing 1.5 kb dna fragment related to salt tolerance were constructed. these recombinant expression vectors were transformed into e. ...200111431992
specific detection of bradyrhizobium and rhizobium strains colonizing rice (oryza sativa) roots by 16s-23s ribosomal dna intergenic spacer-targeted pcr.in addition to forming symbiotic nodules on legumes, rhizobial strains are members of soil or rhizosphere communities or occur as endophytes, e.g., in rice. two rhizobial strains which have been isolated from root nodules of the aquatic legumes aeschynomene fluminensis (irbg271) and sesbania aculeata (irbg74) were previously found to promote rice growth. in addition to analyzing their phylogenetic positions, we assessed the suitability of the 16s-23s ribosomal dna (rdna) intergenic spacer (igs) ...200111472944
a genomic island in pseudomonas aeruginosa carries the determinants of flagellin glycosylation.protein glycosylation has been long recognized as an important posttranslational modification process in eukaryotic cells. glycoproteins, predominantly secreted or surface localized, have also been identified in bacteria. we have identified a cluster of 14 genes, encoding the determinants of the flagellin glycosylation machinery in pseudomonas aeruginosa pak, which we called the flagellin glycosylation island. flagellin glycosylation can be detected only in bacteria expressing the a-type flagell ...200111481492
the diversity of rhizobia nodulating beans in northwest argentina as a source of more efficient inoculant strains.the common bean (phaseolus vulgaris l.) is cultivated widely in central and south america and particularly in the northwest of argentina. in order to describe the diversity of the common bean nodulating rhizobial population from the bean producing area in northwest argentina (nwa), a collection of about 400 isolates of common beans recovered from nodules and soil samples from nwa were characterized by using nifh-pcr, analysis of genes coding for 16s rrna and nodc, and rep-fingerprinting, respect ...200111566389
characterization of a family of arabidopsis genes related to xyloglucan fucosyltransferase1.to understand primary cell wall assembly in arabidopsis, we have focused on identifying and characterizing enzymes involved in xyloglucan biosynthesis. nine genes (atfut2-10) were identified that share between 47% and 62% amino acid similarity with the xyloglucan-specific fucosyltransferase atfut1. reverse transcriptase-pcr analysis indicates that all these genes are expressed. bioinformatic analysis predicts that these family members are fucosyltransferases, and we first hypothesized that some ...200111743104
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 ...199910585971
identification of a plasmid-borne locus in rhizobium etli kim5s involved in lipopolysaccharide o-chain biosynthesis and nodulation of phaseolus vulgaris.screening of derivatives of rhizobium etli kim5s randomly mutagenized with mtn5ssgusa30 resulted in the identification of strain kim-g1. its rough colony appearance, flocculation in liquid culture, and ndv(-) fix(-) phenotype were indicative of a lipopolysaccharide (lps) defect. electrophoretic analysis of cell-associated polysaccharides showed that kim-g1 produces only rough lps. composition analysis of purified lps oligosaccharides from kim-g1 indicated that it produces an intact lps core tris ...199910482500
characterization of a sinorhizobium isolate and its extracellular polymer implicated in pollutant transport in soil.a bacterium isolated from soil (designated 9702-m4) synthesizes an extracellular polymer that facilitates the transport of such hydrophobic pollutants as polynuclear aromatic hydrocarbons, as well as the toxic metals lead and cadmium in soil. biolog analysis, growth rate determinations, and percent g+c content identify 9702-m4 as a strain of sinorhizobium meliloti. sequence analysis of a 16s rdna fragment gives 9702-m4 a phylogenetic designation most closely related to sinorhizobium fredii. the ...200211772656
nolx of sinorhizobium fredii usda257, a type iii-secreted protein involved in host range determination, iis localized in the infection threads of cowpea (vigna unguiculata [l.] walp) and soybean (glycine max [l.] merr.) nodules.sinorhizobium fredii usda257 forms nitrogen-fixing nodules on soybean (glycine max [l.] merr.) in a cultivar-specific manner. this strain forms nodules on primitive soybean cultivars but fails to nodulate agronomically improved north american cultivars. soybean cultivar specificity is regulated by the nolxwbtuv locus, which encodes part of a type iii secretion system (ttss). nolx, a soybean cultivar specificity protein, is secreted by ttss and shows homology to hrpf of the plant pathogen xanthom ...200211790754
identification of two myo-inositol transporter genes of bacillus subtilis.among hundreds of mutants constructed systematically by the japanese groups participating in the functional analysis of the bacillus subtilis genome project, we found that a mutant with inactivation of iolt (ydjk) exhibited a growth defect on myo-inositol as the sole carbon source. the putative product of iolt exhibits significant similarity with many bacterial sugar transporters in the databases. in b. subtilis, the iolabcdefghij and iolrs operons are known to be involved in inositol utilizatio ...200211807058
further studies of the role of cyclic beta-glucans in symbiosis. an ndvc mutant of bradyrhizobium japonicum synthesizes cyclodecakis-(1-->3)-beta-glucosyl.the cyclic beta-(1-->3),beta-(1-->6)-d-glucan synthesis locus of bradyrhizobium japonicum is composed of at least two genes, ndvb and ndvc. mutation in either gene affects glucan synthesis, as well as the ability of the bacterium to establish a successful symbiotic interaction with the legume host soybean (glycine max). b. japonicum strain ab-14 (ndvb::tn5) does not synthesize beta-glucans, and strain ab-1 (ndvc::tn5) synthesizes a cyclic beta-glucan lacking beta-(1-->6)-glycosidic bonds. we det ...199910069844
structural determination of a 5-o-methyl-deaminated neuraminic acid (kdn)-containing polysaccharide isolated from sinorhizobium fredii.the structure of a polysaccharide from sinorhizobium fredii svq293, a thiamine auxotrophic mutant of s. fredii hh103, has been determined. this polysaccharide was isolated following the protocol for lipopolysaccharide extraction. on the basis of monosaccharide analysis, methylation analysis, fast atom bombardment ms, collision-induced dissociation tandem ms, one-dimensional 1h and 13c nmr and two-dimensional nmr experiments, the structure was shown to consist of the following trisaccharide repea ...19989729466
the succinyl and acetyl modifications of succinoglycan influence susceptibility of succinoglycan to cleavage by the rhizobium meliloti glycanases exok and exsh.in rhizobium meliloti (sinorhizobium meliloti) cultures, the endo-1, 3-1,4-beta-glycanases exok and exsh depolymerize nascent high-molecular-weight (hmw) succinoglycan to yield low-molecular-weight (lmw) succinoglycan. we report here that the succinyl and acetyl modifications of succinoglycan influence the susceptibility of succinoglycan to cleavage by these glycanases. it was previously shown that exoh mutants, which are blocked in the succinylation of succinoglycan, exhibit a defect in the pro ...19989696768
functional analysis of hrpf, a putative type iii translocon protein from xanthomonas campestris pv. vesicatoria.type iii secretion systems (ttsss) are specialized protein transport systems in gram-negative bacteria which target effector proteins into the host cell. the ttss of the plant pathogen xanthomonas campestris pv. vesicatoria, encoded by the hrp (hypersensitive reaction and pathogenicity) gene cluster, is essential for the interaction with the plant. one of the secreted proteins is hrpf, which is required for pathogenicity but dispensable for type iii secretion of effector proteins in vitro, sugge ...200211948151
conservation of plasmid-encoded traits among bean-nodulating rhizobium species.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 organizat ...200211976134
key role of bacterial nh(4)(+) metabolism in rhizobium-plant symbiosis.symbiotic nitrogen fixation is carried out in specialized organs, the nodules, whose formation is induced on leguminous host plants by bacteria belonging to the family rhizobiaceae: nodule development is a complex multistep process, which requires continued interaction between the two partners and thus the exchange of different signals and metabolites. nh(4)(+) is not only the primary product but also the main regulator of the symbiosis: either as ammonium and after conversion into organic compo ...200212040124
expression of a serratia marcescens chitinase gene in sinorhizobium fredii usda191 and sinorhizobium meliloti rcr2011 impedes soybean and alfalfa nodulation.a gene encoding chitinase from serratia marcescens bjl200 was cloned into a broad-host-range vector (prk415) and mobilized into sinorhizobium fredii usda191. chitinolytic activity was detected in s. fredii usda191 transconjugants that carried the s. marcescens chib gene. chitinase-producing s. fredii usda191 formed nodules on soybean cultivar mccall. however, there was a delay in nodule formation and a marked decrease in the total number of nodules formed by the chitinase-producing s. fredii in ...199910432638
the diversity of phaseolus-nodulating rhizobial populations is altered by liming of acid soils planted with phaseolus vulgaris l. in brazil.pcr-mediated restriction fragment length polymorphism (rflp) analysis of the 16s-23s rrna internally transcribed spacer (its) region and the 16s rrna gene indicated that the rhizobial populations isolated from common bean (phaseolus vulgaris l.) nodules in the unlimed soil from a series of five lime rates applied 6 years previously to plots of an acidic oxisol had less diversity than those from plots with higher rates of liming. isolates affiliated with rhizobium tropici iib and rhizobium legumi ...200212147504
[study on the improvement of plasmid stability in soybean rhizobia].by using luxab as the report genes, 3.2 kb parcba/de gene fragment from ptr102 was inserted into plafr3 which contained a 3.7 kb enhancing fragment and deleted its cos site. recombinant plasmids phn155 and phn156 were obtained. contrasted plasmids phn157 and phn158 which contained cos site were also constructed. these four plasmids were transferred into sinorhizobium fredii hn01 by tri-parental mating, and plasmid phn155 and phn158 were introduced into bradyrhizobium japonicum ta11 by two-parent ...200012548995
[a sinorhizobium fredll strain that effectively nodulate medicago sativa].sinorhizobium fredii 042bs was isolated from root nodules of alfalfa (medicago sativa) from xinjiang region. nodulation experiments showed that both soybean and alfalfa were nodulated by 042bs effectively. the 16s rdna pcr-rflp analysis was carried out by four restriction endonucleases, and the restriction maps of strain 042bs were identical with those of s. fredii usda205. the dna g + c mol% of strain 042bs was 60.0. the dna homology between 042bs and s. fredii usda205 and usda191 were 84.9% an ...200112549015
[incompatibility among indigenous plasmids of sinorhizobium fredii strains and its application for plasmid curing].the indigenous plasmids of s. frediii hn01 and wwg18 were labeled with tn5-mobsacb. those plasmids were cured on ty medium containing 10% sucrose to identify its function. the psymhn01b of hn01 was transferred into wwg18sr and c361sr. the results of plasmid detection, curing and pot plant experiment revealed that the incompatibility was existed between psym-hn01b and symbiotic plasmid of wwg18sr or the third plasmid of c361sr. but it was compatible with the nonsymbiotic plasmid of wwg18sr and sy ...200112552908
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 ...199910318686
[the cloning and functional analysis of sinorhizobium fredii 042bs regulatory modulation genes].the total dna of sinorhizobium fredii 042bs was digested by ecori for southern blotting with probes of nodd1 and nodd2 from s. fredii usda257. the 3 kb positive band hybrided with nodd1 probe and 6 kb positive band with nodd2 probe were found, respectively. partial gene library were constructed using puc18 as vector, and the clones with the nodd1 and nodd2 genes were obtained. the sequence of nodd1 and nodd2 of 042b showed that they are highly homologous with nodd1 and nodd2 of s. fredii. the fr ...200212557345
soils of the chinese hubei province show a very high diversity of sinorhizobium fredii strains.biodiversity studies of native soybean-nodulating rhizobia in soils from the chinese hubei province (honghu county; ph 8, alluvial soil) have been carried out. inoculation of an american (williams) and an asiatic (peking) soybean cultivar with eleven soil samples led to the isolation of 167 rhizobia strains. the ratio (%) of slow-/fast-growing isolates was different depending on the trap plant used. all isolates were able to nodulate both cultivars, although the n2-fixation efficiency (measured ...200212583720
in silico pattern-based analysis of the human cytomegalovirus genome.more than 200 open reading frames (orfs) from the human cytomegalovirus genome have been reported as potentially coding for proteins. we have used two pattern-based in silico approaches to analyze this set of putative viral genes. with the help of an objective annotation method that is based on the bio-dictionary, a comprehensive collection of amino acid patterns that describes the currently known natural sequence space of proteins, we have reannotated all of the previously reported putative gen ...200312634390
discordant phylogenies within the rrn loci of rhizobia.it is evident from complete genome sequencing results that lateral gene transfer and recombination are essential components in the evolutionary process of bacterial genomes. since this has important implications for bacterial systematics, the primary objective of this study was to compare estimated evolutionary relationships among a representative set of alpha-proteobacteria by sequencing analysis of three loci within their rrn operons. tree topologies generated with 16s rrna gene sequences were ...200312730157
molecular diversity of rhizobia occurring on native shrubby legumes in southeastern australiathe 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 ...19989758831
a new genetic locus in sinorhizobium meliloti is involved in stachydrine utilizationstachydrine, a betaine released by germinating alfalfa seeds, functions as an inducer of nodulation genes, a catabolite, and an osmoprotectant in sinorhizobium meliloti. two stachydrine-inducible genes were found in s. meliloti 1021 by mutation with a tn5-luxab promoter probe. both mutant strains (s10 and s11) formed effective alfalfa root nodules, but neither grew on stachydrine as the sole carbon and nitrogen source. when grown in the absence or presence of salt stress, s10 and s11 took up [14 ...19989758825
genetic diversity of fast-growing rhizobia that nodulate soybean ( glycine max l. merr).the fast-growing rhizobium sp. strain ngr234, isolated from papua new guinea, and 13 strains of sinorhizobium fredii, isolated from china and vietnam, were fingerprinted by means of rapd, rep, eric and ardra. eric, rep and rapd markers revealed a considerable genetic diversity among fast-growing rhizobia. chinese isolates showed higher levels of diversity than those strains isolated from vietnam. ardra analysis revealed three different genotypes among fast-growing rhizobia that nodulate soybean, ...200312802480
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