| 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 ... | 1992 | 1371066 |
| 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. ... | 1992 | 1622264 |
| 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 ... | 1991 | 2007543 |
| 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 ... | 1991 | 2045365 |
| 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 ... | 1988 | 2447061 |
| 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-( ... | 1989 | 2669634 |
| 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 ... | 1985 | 2992376 |
| 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. ... | 1985 | 2999080 |
| 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. | 1986 | 3015025 |
| 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 ... | 1987 | 3025184 |
| 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 ... | 1986 | 3782034 |
| 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) ... | 1986 | 3941043 |
| 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 ... | 1995 | 7635814 |
| 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 ... | 1994 | 8071218 |
| 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 ... | 1994 | 8195084 |
| 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 ... | 1993 | 8382462 |
| 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 ... | 1993 | 8501061 |
| 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 |
| 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 ... | 1996 | 8863426 |
| 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 ... | 1997 | 9141700 |
| 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 ... | 1997 | 9286989 |
| 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 ... | 1997 | 9336948 |
| 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 ... | 1997 | 9434166 |
| 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 |
| 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 ... | 1998 | 9501442 |
| 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 ... | 1998 | 9537364 |
| 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 ... | 1998 | 9573163 |
| 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 ... | 1998 | 9618447 |
| 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 ... | 1998 | 9658006 |
| 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 ... | 1998 | 9696768 |
| 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 ... | 1998 | 9721291 |
| 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 ... | 1998 | 9729466 |
| 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 ... | 1998 | 9733701 |
| 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 |
| 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 ... | 1998 | 9765575 |
| 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 ... | 1998 | 9765576 |
| 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 |
| 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 ... | 1998 | 9835585 |
| 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 ... | 1998 | 9841674 |
| 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 |
| 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 ... | 1999 | 10024556 |
| mutation in gdp-fucose synthesis genes of sinorhizobium fredii alters nod factors and significantly decreases competitiveness to nodulate soybeans. | we mutagenized sinorhizobium fredii hh103-1 with tn5-b20 and screened about 2,000 colonies for increased beta-galactosidase activity in the presence of the flavonoid naringenin. one mutant, designated svq287, produces lipochitooligosaccharide nod factors (lcos) that differ from those of the parental strain. the nonreducing n-acetylglucosamine residues of all of the lcos of mutant svq287 lack fucose and 2-o-methylfucose substituents. in addition, svq287 synthesizes an lco with an unusually long, ... | 1999 | 10065558 |
| 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 ... | 1999 | 10069844 |
| 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, ... | 1999 | 10103242 |
| 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 |
| 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 ... | 1999 | 10388682 |
| 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 ... | 1999 | 10432638 |
| 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 ... | 1999 | 10456941 |
| structural determination of a 5-acetamido-3,5,7, 9-tetradeoxy-7-(3-hydroxybutyramido)-l-glycero-l-manno-nonulos onic acid-containing homopolysaccharide isolated from sinorhizobium fredii hh103. | the structure of a polysaccharide from sinorhizobium fredii hh103 has been determined. this polysaccharide was isolated by following the protocol for lipopolysaccharide extraction. on the basis of monosaccharide analysis, methylation analysis, fast atom bombardment ms, matrix-assisted laser desorption ionization ms, electron-impact high-resolution ms, one-dimensional (1)h-nmr and (13)c-nmr and two-dimensional nmr experiments, the structure was shown to consist of a homopolymer of a 3:1 mixture o ... | 1999 | 10477263 |
| 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 ... | 1999 | 10543844 |
| 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 |
| 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 |
| structural characterization of the released polysaccharide of desiccation-tolerant nostoc commune drh-1. | the structure of the viscous extracellular polysaccharide (glycan) of desiccation-tolerant nostoc commune drh-1 was determined through chromatographic and spectroscopic methods. the polysaccharide is novel in that it possesses a 1-4-linked xylogalactoglucan backbone with d-ribofuranose and 3-o-[(r)-1-carboxyethyl]-d-glucuronic acid (nosturonic acid) pendant groups. the presence of d-ribose and nosturonic acid as peripheral groups is unusual, and their potential roles in modulating the rheologica ... | 2000 | 10648523 |
| 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 |
| 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 ... | 2000 | 10714988 |
| 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 |
| 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 ... | 2000 | 10762258 |
| characterization of an atrazine-degrading pseudaminobacter sp. isolated from canadian and french agricultural soils. | atrazine, a herbicide widely used in corn production, is a frequently detected groundwater contaminant. fourteen bacterial strains able to use this herbicide as a sole source of nitrogen were isolated from soils obtained from two farms in canada and two farms in france. these strains were indistinguishable from each other based on repetitive extragenic palindromic pcr genomic fingerprinting performed with primers eric1r, eric2, and boxa1r. based on 16s rrna sequence analysis of one representativ ... | 2000 | 10877767 |
| 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 ... | 2000 | 10877782 |
| 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 |
| 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. | 2000 | 10919829 |
| 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 ... | 2000 | 10940010 |
| 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. ... | 2000 | 10975657 |
| keys to symbiotic harmony. | | 2000 | 11004160 |
| 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 |
| 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 |
| 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 |
| 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 ... | 2001 | 11157937 |
| potential symbiosis-specific genes uncovered by sequencing a 410-kilobase dna region of the bradyrhizobium japonicum chromosome. | the physical and genetic map of the bradyrhizobium japonicum chromosome revealed that nitrogen fixation and nodulation genes are clustered. because of the complex interactions between the bacterium and the plant, we expected this chromosomal sector to contain additional genes that are involved in the maintenance of an efficient symbiosis. therefore, we determined the nucleotide sequence of a 410-kb region. the overall g+c nucleotide content was 59.1%. using a minimum gene length of 150 nucleotid ... | 2001 | 11157954 |
| 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 |
| 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 |
| determination of the chemical structure of the capsular polysaccharide of strain b33, a fast-growing soya bean-nodulating bacterium isolated from an arid region of china. | we have determined the structure of a polysaccharide from strain b33, a fast-growing bacterium that forms nitrogen-fixing nodules with asiatic and american soya bean cultivars. on the basis of monosaccharide analysis, methylation analysis, one-dimensional 1h- and 13c-nmr and two-dimensional nmr experiments, the structure was shown to consist of a polymer having the repeating unit -->6)-4-o-methyl-alpha-d-glcp-(1-->4)-3-o-methyl-beta-d-glcpa-(1--> (where glcpa is glucopyranuronic acid and glcp is ... | 2001 | 11439101 |
| 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) ... | 2001 | 11472944 |
| 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 ... | 2001 | 11481492 |
| 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 ... | 2001 | 11566389 |
| site-specific integrative elements of rhizobiophage 16-3 can integrate into proline trna (cgg) genes in different bacterial genera. | the integrase protein of the rhizobium meliloti 41 phage 16-3 has been classified as a member of the int family of tyrosine recombinases. the site-specific recombination system of the phage belongs to the group in which the target site of integration (attb) is within a trna gene. since trna genes are conserved, we expected that the target sequence of the site-specific recombination system of the 16-3 phage could occur in other species and integration could take place if the required putative hos ... | 2002 | 11741858 |
| 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 ... | 2001 | 11743104 |
| [diversity of sinorhizobium fredii strains]. | rhizobial strains were isolated from soils growing with soybean cultivar heilong 33 and willimas. fifty sinorhizobium fredii strains were chosen, and their biological characteristics including growth velocity, acid-alkali endurance, resistance of intrinsic antibiotics, utilization of carbon and nitrogen sources, absorption of congo red, ability of melanin production, and plasmid profiles were comparatively researched. the dendrogram was described using the method of cluster analysis, and the bio ... | 2001 | 11758392 |
| 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 ... | 2002 | 11790754 |
| sinorhizobium fredii hh103 has a truncated nolo gene due to a -1 frameshift mutation that is conserved among other geographically distant s. fredii strains. | strain svq121 is a mutant derivative of sinorhizobium fredii hh103 carrying a transposon tn5-lacz insertion into the nolo-coding region. sequence analysis of the wild-type gene revealed that it is homologous to that of rhizobium sp. ngr234, which is involved in the 3 (or 4)-o-carbamoylation of the nonreducing terminus of nod factors. downstream of nolo, as in rhizobium sp. ngr234, the noei gene responsible for methylation of the fucose moiety of nod factors was found. svq121 nod factors showed l ... | 2002 | 11878319 |
| [a study of the effects on the symbiotic nitrogen fixation of sinorhizobium fredii with the introduction of dctabd and nifa genes]. | a recombinant plasmid phn307 containing c4-dicarboxylic acid transport genes (dctabd) from sinorhizobium meliloti, nifa genes from klebsiella pneumoniae and reporter genes luxab from pdb30 was constructed by using ptr102 as the vector. the phn307 was then introduced into the s. fredii hn01, yc4 and gr3 by tri-parental mating, and the stability of phn307 in the transconjugants under free-living and symbiotic condition was also investigated. the results of plant pot experiment indicated that the i ... | 2002 | 11902003 |
| 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 ... | 2002 | 11807058 |
| 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 ... | 2002 | 11948151 |
| 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 ... | 2002 | 11976134 |
| 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 ... | 2002 | 12040124 |
| [effect of ph on nodulation of soybean rhizobia from weifang and huayuankou soils]. | the effect of ph on the nodulation of sinorhizobium fredii and bradyrhizobium japonicum was examined by analyzing the indigent soybean rhizobia, predominant indigent rhizobia, and specific rhizobia, respectively. the results showed that very acid and very alkaline environment could retard the nodulation and inhibit the growth of the rhizobia. sinorhizohium fredii could endure environment more strongly than bradyrhizobium japonicum, and had a high competitive nodulation capacity. bradyhizobium ja ... | 2001 | 11758403 |
| 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 ... | 2002 | 12147504 |
| improved soybean root association of n-starved bradyrhizobium japonicum. | in this study, we addressed the effects of n limitation in bradyrhizobium japonicum for its association with soybean roots. the wild-type strain lp 3001 grew for six generations with a growth rate of 1.2 day(-1) in a minimal medium with 28 mm mannitol as the carbon source and with the n source [(nh(4))(2)so(4)] limited to only 20 microm. under these conditions, the glutamine synthetase (gs) activity was five to six times higher than in similar cultures grown with 1 or 0.1 mm (nh(4))(2)so(4). the ... | 2001 | 11717284 |
| [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. ... | 2001 | 11431992 |
| [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 ... | 2001 | 12552908 |
| [construction of a gfp broad-host-range promoter-probe vector and its application]. | the 0.9 kb dna fragment was obtained by pcr and using a pair of special designed primers from the green fluorescent protein gene(gfp). it was then cloned into an expression vector pet-11c and named as phn115. a promoferless gfp vector with sd fragment was obtained from phn115 and subcloned into sk(+), pij 2925 and finally into ptr102. a broad-hast-range and visible promoter-probe vector, phn127 was constructed and used successfully for the identification of constitutive and inducible promoters f ... | 1999 | 12555521 |
| preparation, immunogenicity, and protective efficacy, in a murine model, of a conjugate vaccine composed of the polysaccharide moiety of the lipopolysaccharide of vibrio cholerae o139 bound to tetanus toxoid. | the epidemic and pandemic potential of vibrio cholerae o139 is such that a vaccine against this newly emerged serogroup of v. cholerae is required. a conjugate made of the polysaccharide moiety (o-specific polysaccharide plus core) of the lipopolysaccharide (lps) of v. cholerae o139 (pmlps) was prepared by derivatization of the pmlps with adipic acid dihydrazide and coupling to tetanus toxoid (tt) by carbodiimide-mediated condensation. the immunologic properties of the conjugate were tested usin ... | 2001 | 11292781 |
| 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 ... | 2002 | 12583720 |
| [subcloning and sequencing of dna fragment related to salt tolerance in sinorhizobium fredii rt19]. | a 23 kb dna fragment related to salt tolerance was obtained from the gene library of s. fredii strain rt19. in this study, bamh i was selected to digest 23 kb dna fragment into different length of dna fragments. the resulting fragments were ligated with plasmid pml122, then the recombinant plasmids were transformed to competent cells of e. coli s17-1 on selective medium and three transformants tr were obtained. two-parental mating experiments were carried out with these transformants as donor an ... | 2000 | 11192438 |
| 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 ... | 2003 | 12730157 |
| 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 ... | 2000 | 11012780 |
| citrate synthase mutants of sinorhizobium fredii usda257 form ineffective nodules with aberrant ultrastructure. | the tricarboxylic acid (tca) cycle plays an important role in generating the energy required by bacteroids to fix atmospheric nitrogen. citrate synthase is the first enzyme that controls the entry of carbon into the tca cycle. we cloned and determined the nucleotide sequence of the glta gene that encodes citrate synthase in sinorhizobium fredii usda257, a symbiont of soybeans (glycine max [l.] merr.) and several other legumes. the deduced citrate synthase protein has a molecular weight of 48,198 ... | 2003 | 12788763 |
| studies on the solution conformation and dynamics of a polysaccharide from sinorhizobium fredii hh103 and its monosaccharide repeating unit. | the conformational behavior of the homopolysaccharide isolated from sinorhizobium fredii hh103 and its monosaccharide repeating unit (5-acetamido-3,5,7,9-tetradeoxy-7-(3-hydroxybutyramido)-l-glycero- l- manno-nonulosonic acid) was analyzed by nuclear magnetic resonance (nmr) spectroscopy and extensive molecular dynamics simulations (md). the results indicate that the glycosidic linkages and lateral chains may adopt a variety of conformations. md simulations using the generalized born solvent-acc ... | 2000 | 10994517 |