Publications
| Title | Abstract | Year(sorted descending) Filter | PMID Filter |
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| role of pili (fimbriae) in attachment of bradyrhizobium japonicum to soybean roots. | pili (fimbriae) were observed on cells of each of the five strains of bradyrhizobium japonicum and the one strain of rhizobium trifolii examined. pili on b. japonicum were about 4 nm in diameter and polarly expressed. piliated cells were estimated by transmission electron microscopy and hydrophobic attachment to polystyrene to constitute only a small percentage of the total population. the proportion of piliated cells in these populations was dependent on culture age in some strains. piliated b. ... | 1986 | 16347100 |
| autecology in rhizospheres and nodulating behavior of indigenous rhizobium trifolii. | indigenous serotype 1-01 of rhizobium trifolii occupied significantly fewer nodules (6%) on plants of soil-grown noninoculated subterranean clover (trifolium subterraneum l.) cv. woogenellup than on cv. mt. barker (36%) sampled at the flowering stage of growth. occupancy by indigenous serotype 2-01, was not significantly different on the two cultivars (16 and 26%). serotype-specific, fluorescent-antibody conjugates were synthesized and used to enumerate the indigenous serotypes in host (clovers) ... | 1986 | 16347198 |
| interstrain competition between representatives of indigenous serotypes of rhizobium trifolii. | the symbiotic characteristics of rhizobium trifolii strains 1-01 and 2-01 were evaluated both individually and in various combinations on two cultivars (mt. barker and woogenellup) of subterranean clover (trifolium subterraneum l.). nodules were observed on day 8 independent of cultivar or strain. cultivar differences were measured in nodulating efficiency by 1-01 since 54% of the primary nodules were formed on cv. mt. barker and only 15% were formed on cv. woogenellup in the zone above, or 1 cm ... | 1986 | 16347199 |
| rhizobium trifolii 0403 is capable of growth in the absence of combined nitrogen. | rhizobium trifolii 0403 was treated with 16.6 mm succinate and other nutrients and thereby induced to grow in nitrogen-free medium. the organism grew microaerophilically on either semisolid or liquid medium, fixing atmospheric nitrogen to meet metabolic needs. nitrogen fixation was measured via n incorporation (18% n enrichment in 1.5 doublings) and acetylene reduction. nitrogen-fixing cells had a k(m) for acetylene of 0.07 atm (ca. 7.09 kpa), required about 3% oxygen for optimum growth in liqui ... | 1986 | 16347203 |
| dna sequence of rhizobium trifolii nodulation genes reveals a reiterated and potentially regulatory sequence preceding nodabc and nodfe. | the rhizobium trifolii nod genes required for host-specific nodulation of clovers are located on 14 kb of sym (symbiotic) plasmid dna. analysis of the nucleotide sequence of a 3.7 kb portion of this region has revealed open reading frames corresponding to the nodabcdef genes. a dna sequencing technique, using primer extension from within tn5, has been used to determine the precise locations of tn5 mutations within the nod genes and the phenotypes of the corresponding mutants correlate with their ... | 1986 | 3008100 |
| nodulation inhibition by rhizobium leguminosarum multicopy nodabc genes and analysis of early stages of plant infection. | during analysis of early events in the infection and nodulation of vicia hirsuta roots inoculated with normal and mutant strains of rhizobium leguminosarum and strains containing cloned nodulation (nod) genes, a number of novel observations were made. (i) alternating zones of curled and straight root hairs were seen on roots of v. hirsuta inoculated with the wild-type strain of r. leguminosarum. this phasing of root hair curling was not seen if plants were grown under continuous light or continu ... | 1986 | 3009408 |
| the nodi gene product of rhizobium leguminosarum is closely related to atp-binding bacterial transport proteins; nucleotide sequence analysis of the nodi and nodj genes. | the nucleotide sequence of a 2-kb fragment immediately downstream of the nodabc genes of the rhizobium leguminosarum symbiotic plasmid prl1ji has been determined. genes corresponding to the two open reading frames identified are named nodi and nodj. tn 5 insertions into these genes result in a "nodulation-delayed" phenotype. the predicted amino acid sequence of the nodi gene shows considerable homology to inner-membrane-located gene products involved in active transport systems in escherichia co ... | 1986 | 3019841 |
| construction of a tn5 derivative determining resistance to gentamicin and spectinomycin using a fragment cloned from r1033. | a physical and genetic map of the incp plasmid r1033 was constructed: restriction fragments were subcloned and antibiotic resistance genes were located. the map is consistent with previous reports that r1033 is a derivative of rp4 carrying a 16-kb transposon tn1696 which contains the antibiotic-resistance determinants present on r1033 but not on rp4. a bamhi fragment from r1033, determining resistance to gentamicin, spectinomycin and streptomycin, was cloned into tn5, replacing the central bg/ii ... | 1986 | 3030896 |
| characterization and cloning of two rhizobium leguminosarum genes coding for glutamine synthetase activities. | we have demonstrated that rhizobium leguminosarum strain lpr1105 contains a heat stable and a heat labile glutamine synthetase (ec 6.3.1.2) activity similar to those described for other rhizobiaceae. most of the activity is heat stable when this strain is grown on glutamine as sole nitrogen source, but most is heat labile when grown on nitrate. using a gene bank of r. leguminosarum dna we have isolated two clones, which code for heat stable (p7d9) and heat labile (p4f7) glutamine synthetase acti ... | 1986 | 2878969 |
| iron requirement of rhizobium leguminosarum and secretion of anthranilic acid during growth on an iron-deficient medium. | rhizobium leguminosarum gf160 required iron for growth under aerobic conditions in a chemically defined medium. maximal growth of bacteria previously depleted in iron was obtained with approximately 50 microm unchelated ferric iron and with glucose as the only carbon source. growth under iron deficiency did not result in the production of detectable levels of siderophores of either the catechol or hydroxamate types. growing cells released a fe3+-reducing agent that was identified as anthranilic ... | 1986 | 3729413 |
| anthranilate-promoted iron uptake in rhizobium leguminosarum. | anthranilate promoted the uptake of ferric iron into iron-starved cells of rhizobium leguminosarum gf160. the uptake system was a saturable function of the concentration of ferric anthranilate. it was characterized by an apparent km of 6 microm and a vmax of 1.6 nmol/min/mg cell protein. uptake was temperature dependent and inhibited by the metabolic poisons arsenate and iodoacetate. the proton motive force may not be involved since no effect was demonstrated by the respiratory inhibitor sodium ... | 1986 | 3729414 |
| fractionation of rhizobium leguminosarum cells into outer membrane, cytoplasmic membrane, periplasmic, and cytoplasmic components. | rhizobium leguminosarum cells were separated into four distinct fractions by using density gradient centrifugation for the separation of the outer and cytoplasmic membranes and lysozyme-edta treatment of whole cells for the isolation of the periplasmic and cytoplasmic fractions. these methods allowed the subcellular localization of r. leguminosarum proteins. | 1986 | 3745116 |
| correlation between extracellular fibrils and attachment of rhizobium leguminosarum to pea root hair tips. | as part of a project meant to characterize molecules involved in nodulation, a semiquantitative microscopic assay was developed for measuring attachment of rhizobium leguminosarum cells to pea root hair tips, i.e., the site at which r. leguminosarum initiates nodulation. this form of attachment, designated as cap formation, was dependent on the incubation ph and growth phase, with optimal attachment at ph 7.5 and with bacteria in the early stationary phase of growth. addition of glucose to the g ... | 1986 | 3782027 |
| biosynthesis of rhizobium trifolii capsular polysaccharide: enzymatic transfer of pyruvate substitutions into lipid-bound saccharide intermediates. | the activity of capsular polysaccharide pyruvyltransferase catalyzing the pyruvylation of acidic heteropolysaccharide was measured in rhizobium trifolii 843 and 0403 rif. this enzyme activity was determined with edta-treated cells, uridine diphosphate-sugar precursors, and phosphoenol [1-14c]pyruvate. activity was measured by the incorporation of radioactivity into organic solvent-soluble glycoconjugates. enzymatic pyruvylation of capsular polysaccharide occurred from phosphoenolpyruvate at the ... | 1986 | 3782043 |
| [nitrogenase, hydrogenase and nitrate reductase activities, oxygen consumption, and atp content in nodules formed by strains of rhizobium leguminosarum 128c53 and 300 in symbiosis with pea plants]. | the nitrogenase activity, nitrate reductase activity and oxygen uptake as well as the hydrogen incorporation and atp content were examined in the root nodules and bacteroids, respectively, formed by rhizobium leguminosarum strains 128c53 (hydrogenase positive) and 300 (hydrogenase negative) in symbiosis with pisum sativum plants grown in the presence of 2 mm kno3. the strain 128c53 showed the greatest values for all parameters analyzed, except for the nitrate reductase activity, which was higher ... | 1986 | 3078142 |
| 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 |
| role of plant root exudate and sym plasmid-localized nodulation genes in the synthesis by rhizobium leguminosarum of tsr factor, which causes thick and short roots on common vetch. | in a previous paper it was shown that cocultivation of rhizobium leguminosarum with the plant vicia sativa subsp. nigra on solid medium causes a changed mode of growth of the plant roots, resulting in thick and short roots (tsr). the sym plasmid present in the bacterium appeared to be essential for causing tsr (a. a. n. van brussel, t. tak, a. wetselaar, e. pees, and c. a. wijffelman, plant sci. lett. 27:317-325, 1982). in the present paper, we show that a role in causing tsr is general for sym ... | 1986 | 3944060 |
| location and identity of the acyl substituents on the extracellular polysaccharides of rhizobium trifolii and rhizobium leguminosarum. | the basic structures of the extracellular polysaccharides of rhizobium leguminosarum and rhizobium trifolii were found to be identical, but their acylation patterns differ. liquid hydrogen fluoride at -40 degrees degrades the two polysaccharides to a series of oligosaccharides representing the repeating units of the polysaccharides and their higher homologs. at -23 degrees, it degrades the polymers to a mixture of oligosaccharides from which a tetrasaccharide constituting a unit of the backbone ... | 1986 | 3955563 |
| conserved nodulation genes from the non-legume symbiont bradyrhizobium sp. (parasponia). | a nodulation locus from the broad-host-range, non-legume symbiont bradyrhizobium sp. (parasponia) strain anu289, has been identified by hybridisation to cloned rhizobium trifolii nodulation (nod) genes. transfer of cloned anu289 nod genes to r.trifolii nodulation-deficient mutants showed that the locus contains a functional homologue of the r. trifolii nodd gene. dna sequence analysis revealed the presence of three additional genes noda, nodb and nodc clustered adjacent to nodd. the four genes f ... | 1986 | 3960737 |
| rhizobium meliloti genes required for nodule development are related to chromosomal virulence genes in agrobacterium tumefaciens. | symbiotically essential genes have been identified in rhizobium meliloti that are structurally and functionally related to chromosomal virulence (chv) genes of agrobacterium tumefaciens. homologous sequences also exist in the genomes of other fast-growing rhizobia including rhizobium trifolii, rhizobium leguminosarum, and rhizobium phaseoli. in agrobacterium, the chva and chvb loci are known to be essential for oncogenic transformation of dicotyledonous plants and for attachment to plant cells [ ... | 1986 | 16593714 |
| a structural comparison of the acidic extracellular polysaccharides from rhizobium trifolii mutants affected in root hair infection. | the structures of the acidic extracellular polysaccharides (epss) from several r. trifolii mutants were compared by examining their compositions and their sugar linkages as determined by methylation analysis. these mutant strains were derived from the wild-type r. trifolii anu843 and were unable to induce normal root hair curling (hac- phenotype) or nodulation response (nod- phenotype) in clover plants. these strains included several transposon tn5-induced nod-mutants, strain anu871, which posse ... | 1986 | 16664568 |
| stimulation of nodulation in the clover-rhizobium trifolii 0403 system by penicillin and mecillinam. | the number of nodules produced per clover seedling inoculated with rhizobium trifolii 0403 can be increased almost 2-fold by the addition of penicillin or mecillinam. two-day-old dutch white clover seedlings grown in 250 milliliter boston round jars containing agar-solidified plant growth medium were inoculated with exponentially growing rhizobium trifolii 0403 cells. penicillin or mecillinam (100 micrograms per milliliter) were added immediately or after 24 hours. following 42 days growth, 10 r ... | 1986 | 16664802 |
| the relationship between h(2) evolution and acetylene reduction in pisum sativum-rhizobium leguminosarum symbioses differing in uptake hydrogenase activity. | peas (pisum sativum l.) were inoculated with strains of rhizobium leguminosarum having different levels of uptake hydrogenase (hup) activity and were grown in sterile leonard jars under controlled conditions. rates of h(2) evolution and acetylene reduction were determined for intact nodulated roots at intervals after the onset of darkness or after removal of the shoots. hup activity was estimated using treatment plants or equivalent plants from the growth chamber, by measuring the uptake of h(2) ... | 1986 | 16664984 |
| sodium stimulation of uptake hydrogenase activity in symbiotic rhizobium. | initial observations showed a 100% increase in h(2)-uptake (hup) activity of rhizobium leguminosarum strain 3855 in pea root nodules (pisum sativum l. cv alaska) on plants growing in a baked clay substrate relative to those growing in vermiculite, and an investigation of nutrient factors responsible for the phenomenon was initiated. significantly greater hup activity was first measured in the clay-grown plants 24 days after germination, and higher activity was maintained relative to the vermicul ... | 1986 | 16665057 |
| the rhizobium leguminosarum nodulation gene nodf encodes a polypeptide similar to acyl-carrier protein and is regulated by nodd plus a factor in pea root exudate. | the dna sequence of approximately 3.5 kb of the nodulation (nod) region of the rhizobium leguminosarum symbiotic plasmid prl1ji was determined. three open reading frames were identified; genes corresponding to these have been called nodd, node and nodf.nodd is adjacent to noda and is transcribed in the opposite direction. the nodf and node genes are downstream of, and transcribed in the same direction as, nodd with 667 nucleotides between nodd and nodf and three nucleotides separating nodf and n ... | 1986 | 16453679 |
| the nodd gene of rhizobium leguminosarum is autoregulatory and in the presence of plant exudate induces the noda,b,c genes. | to analyse nod gene expression in rhizobium leguminosarum, a broad host-range lacz protein fusion vector was constructed. two protein fusions, nodc-lacz and nodd-lacz, were used to measure the regulation of expression of the promoters of the noda,b,c and the nodd transcripts by measuring the induced levels of beta-galactosidase activity in r. leguminosarum. in the absence of plant root exudate the nodd-lacz hybrid was expressed but the nodc-lacz hybrid was not. the expression of the nodd-lacz hy ... | 1985 | 16453650 |
| intra- and interspecies transfer and expression of rhizobium japonicum hydrogen uptake genes and autotrophic growth capability. | cosmids containing hydrogen uptake genes have previously been isolated in this laboratory. four new cosmids that contain additional hup gene(s) have now been identified by conjugal transfer of a rhizobium japonicum 122des gene bank into a tn5-generated hup(-) mutant and screening for the acquisition of hup activity. the newly isolated cosmids, phu50-phu53, contain part of the previously isolated phu1 but extend as far as 20 kilobases beyond its border. phu52 complements five of six hup(-) mutant ... | 1985 | 16578786 |
| effect of temperature on h(2) evolution and acetylene reduction in pea nodules and in isolated bacteroids. | nitrogenase (ec 1.7.99.2) activity in pea (pisum savitum) nodules formed after infection with rhizobium leguminosarum (lacking uptake hydrogenase) was measured as acetylene reduction, h(2) evolution in air and h(2) evolution in ar:o(2). with detached roots the relative efficiency, calculated from acetylene reduction, showed a decrease (from 55 to below 0%) with increasing temperature. with excised nodules and isolated bacteroids similar results were obtained. however, the relative efficiency cal ... | 1985 | 16664054 |
| nodules are induced on alfalfa roots by agrobacterium tumefaciens and rhizobium trifolii containing small segments of the rhizobium meliloti nodulation region. | regions of the rhizobium meliloti nodulation genes from the symbiotic plasmid were transferred to agrobacterium tumefaciens and rhizobium trifolii by conjugation. the a. tumefaciens and r. trifolii transconjugants were unable to elicit curling of alfalfa root hairs, but were able to induce nodule development at a low frequency. these were judged to be genuine nodules on the basis of cytological and developmental criteria. like genuine alfalfa nodules, the nodules were initiated from divisions of ... | 1985 | 3968028 |
| sym plasmid genes of rhizobium trifolii expressed in lignobacter and pseudomonas strains. | a 14-kilobase (kb) fragment of rhizobium trifolii sym plasmid containing nodulation (nod) genes or the psym plasmid of r. trifolii cointegrated with a broad-host-range vector r68.45 (ppn1) were transferred to lignobacter strain k17 and pseudomonas aeruginosa strain pao5 by conjugation. lignobacter transconjugants carrying sym plasmid ppn1 formed nodules on white, red, and subterranean clover plants. lignobacter transconjugants containing a 14-kb fragment of nod genes cloned into a multicopy plas ... | 1985 | 3997778 |
| chemotaxis to aromatic and hydroaromatic acids: comparison of bradyrhizobium japonicum and rhizobium trifolii. | rhizobia are bacteria well known for their ability to fix nitrogen in symbiosis with leguminous plants. members of diverse rhizobial species grow at the expense of hydroaromatic and aromatic compounds commonly found in plant cells and plant litter. using a quantitative capillary assay to measure chemotaxis, we tested the ability of hydroaromatic acids, selected aromatic acids, and their metabolites to serve as chemoattractants for two distantly related rhizobial species, bradyrhizobium japonicum ... | 1985 | 4019407 |
| expression of rhizobium trifolii early nodulation genes on maize and rice plants. | an incq multicopy vector (pkt230) and an incp1 low-copy-number vector (prk290), both carrying rhizobium trifolii root hair curling (hac) genes, were transferred to a sym plasmid-cured derivative of r. trifolii anu843. the resulting transconjugants were used to inoculate the monocotyledonous plants sorghum, maize, rice, and wheat. transconjugants carrying the hac genes on the multicopy vector caused a root hair curling response on maize and rice plants 14 days after inoculation. | 1985 | 4019418 |
| characterization and primary structures of dna-binding hu-type proteins from rhizobiaceae. | the dna-binding hu-type proteins from several species of rhizobiaceae including rhizobium meliloti, two strains of rhizobium leguminosarum with highly different phenotypic characters and agrobacterium tumefaciens, were characterized and their amino acid sequences were determined. hu-type proteins isolated from r. leguminosarum l18 and a. tumefaciens are identical and show slight differences with the r. meliloti hu-type protein. on the other hand the r. leguminosarum l53 hu-type protein is quite ... | 1985 | 4038648 |
| isolation and partial characterization of the extracellular polysaccharides and lipopolysaccharides from fast-growing rhizobium japonicum usda 205 and its nod- mutant, hc205, which lacks the symbiotic plasmid. | the extracellular polysaccharides and lipopolysaccharides (lpss) from two fast-growing rhizobium japonicum strains, usda 205 and hc205, were isolated and partially characterized. strain hc205 is a nod- mutant of usda 205 which lacks the symbiotic plasmid. the extracellular polysaccharides from both strains are very similar in composition, having galactose, glucose, glucuronic acid, and acyl groups. the extracellular polysaccharides do not contain detectable levels of pyruvate. methylation analys ... | 1985 | 4091554 |
| characterization of the anomalous infection and nodulation of subterranean clover roots by rhizobium leguminosarum 1020. | anomalous nodulation of trifolium subterraneum (subterranean clover) roots by rhizobium leguminosarum 1020 was examined as a model of modified host-specificity in a rhizobium-legume symbiosis. consistent with previous reports, these nodules (i) appeared most often at sites of secondary root emergence, (ii) were ineffective in nitrogen fixation and (iii) were as numerous as nodules formed by an effective rhizobium trifolii strain. r. leguminosarum 1020, grown on agar plates or in the clover root ... | 1985 | 3831234 |
| rhizobium leguminosarum genes involved in early stages of nodulation. | nodulation genes from rhizobium leguminosarum have been subcloned and transferred to a strain of r. phaseoli with its symbiotic plasmid deleted (and therefore its nodulation and nitrogen fixation genes). normal infection and nodule development occurred when these strains were added to the roots of pisum sativum (peas) and vicia hirsuta. the pea nodules were examined by electron microscopy; bacteroid forms were seen surrounded by peribacteroid membranes and using immuno-gold labelling it was show ... | 1985 | 3867677 |
| 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 |
| root hair deformations associated with fractionated extracts from rhizobium trifolii. | components from culture fluid and whole cells of rhizobium trifolii were examined for effects on root hair morphology of white clover seedlings (trifolium repens var. ladino). cell-free culture fluid, exopolysaccharides, supernatant fluid from the precipitation of the exopolysaccharides, capsular polysaccharides, lipopolysaccharides, and a protein fraction from culture fluids were assayed for morphogenetic effects on the root hairs of axenically grown clover seedlings. crude fractions were chrom ... | 1985 | 16346709 |
| possible involvement of phage-like structures in antagonism of cowpea rhizobia by rhizobium trifolii. | a reduction in the viability of cowpea rhizobia was observed when rhizobium trifolii iari and cowpea rhizobium strain 3824 were inoculated together in soil. the reduction in number of cowpea rhizobia in soil was found to be associated with the reduction in number of nodules per plant and retardation in plant growth. an antimicrobial substance was isolated from r. trifolii which, on electron microscopic investigation, demonstrated the presence of several phage-like structures. | 1985 | 16346736 |
| inoculant maturity influences survival of rhizobia on seed. | survival of rhizobium trifolii on seeds of arrowleaf clover (trifolium versiculosum savi) and subclover (trifolium subterraneum l.) was affected by the maturity of peat-, vermiculite-, and charcoal-based inoculants. ten times more rhizobia survived on seed 4 days after inoculation when inoculants were stored (cured) before being utilized as compared with uncured inoculants. increasing the curing time of inoculants beyond 4 weeks had little effect on increasing survival of seed-applied rhizobia. | 1985 | 16346738 |
| studies on the inoculation and competitiveness of a rhizobium leguminosarum strain in soils containing indigenous rhizobia. | the competitiveness of a rhizobium leguminosarum strain was investigated at two separate locations in field inoculation studies on commercially grown peas. the soil at each location (sites i and ii) contained an indigenous r. leguminosarum population of ca. 3 x 10 rhizobia per g of soil. at site i it was necessary to use an inoculum concentration as large as 4 x 10 cfu ml (2 x 10 bacteria seed) to establish the inoculum strain in the majority of nodules (73%). however, at site ii the inoculum st ... | 1985 | 16346769 |
| influence of azospirillum strains on the nodulation of clovers by rhizobium strains. | mixed cultures of several azospirillum and rhizobium trifolii strains caused either an inhibition or stimulation of nodule formation on plant hosts as compared with nodulation of plants inoculated with r. trifolii alone. azospirillum strains affected the nodulation process at a precise cell ratio (r. trifolii/azospirillum cells) and time of inoculation. all azospirillum strains used showed a variation in their ability to inhibit or enhance nodulation by r. trifolii strains. when nonviable cell p ... | 1985 | 16346772 |
| interaction of azospirillum and rhizobium strains leading to inhibition of nodulation. | rhizobium-azospirillum interactions during establishment of rhizobium-clover symbiosis were studied. when mixed cultures of azospirillum and rhizobium trifolii strains were simultaneously inoculated onto clover plants, no nodulation by r. trifolii was observed. r. trifolii anu1030, which nodulated clover plants without attacking root hairs, i.e., does not cause root hair curling (hac), did not show inhibition of nodulation when inoculated together with azospirillum strains. isolation of bacteria ... | 1985 | 16346773 |
| conserved nodulation genes in rhizobium meliloti and rhizobium trifolii. | plasmids which contained wild-type or mutated rhizobium meliloti nodulation (nod) genes were introduced into nodr. trifolii mutants anu453 and anu851 and tested for their ability to nodulate clover. cloned wild-type and mutated r. meliloti nod gene segments restored anu851 to nod, with the exception of nodd mutants. similarly, wild-type and mutant r. meliloti nod genes complemented anu453 to nod, except for nodcii mutants. thus, anu851 identifies the equivalent of the r. meliloti nodd genes, and ... | 1985 | 16346809 |
| association of rhizobium strains with roots of trifolium repens. | two techniques were used to assess the binding of rhizobia to clover roots: indirect counting after radiolabeling the bacteria and direct counting by using phase-contrast microscopy. microscopic observations revealed a large variability in the number of bacteria associated with individual root hairs. this variability made unbiased counting by microscopy difficult. systematic examination of all visible root hairs and "blind" counting of coded strains and treatments were adopted to minimize observ ... | 1985 | 16346819 |
| uptake hydrogenase activity determined by plasmid prl6ji in rhizobium leguminosarum does not increase symbiotic nitrogen fixation. | six mutants of rhizobium leguminosarum 3855 lacking uptake hydrogenase activity (hup phenotype) as a result of tn5-mob mutagenesis of the hup-containing plasmid prl6ji were tested for symbiotic performance on pisum sativum l. and vicia benghalensis l. three pea cultivars and one vetch line, which induce four different levels of hup activity in strain 3855, were grown to flowering under microbiologically controlled conditions in the absence of combined n. direct kjeldahl n measurements showed tha ... | 1985 | 16346912 |
| effect of plasmid pij1008 from rhizobium leguminosarum on symbiotic function of rhizobium meliloti. | plasmid pij1008, which carries determinants for uptake hydrogenase (hup) activity, was transferred from rhizobium leguminosarum to rhizobium meliloti without impairing the capacity of the latter species to form root nodules on alfalfa. the plasmid was still present in rhizobia reisolated from the root nodules of 12 different alfalfa cultivars, but only low levels of hup activity were detected in alfalfa. | 1984 | 16346527 |
| fine structure of succinate-swollen rhizobium trifolii 0403. | transmission electron micrographs of glutaraldehyde- oso(4)-fixed rhizobium trifolii 0403 before and after cells were treated with 16.6 mm succinate showed that treated cells increased in mass by increasing cytoplasmic volume. the morphology of succinate-treated cells was identical to that of bacteroids, and the appearances of the envelope and periplasmic space were similar. the primary difference was in inclusion number and type. | 1984 | 16346547 |
| root hair deformation, bacterial attachment, and plant growth in wheat-azospirillum associations. | seven azospirillum strains induced more deformation of root hairs of wheat than did strains of rhizobium leguminosarum, azotobacter chroococcum, or escherichia coli. azospirillum sp. strain sp245 caused the most deformation. strain sp245 (isolated from surface sterile roots of wheat) and strain sp7 (isolated from the rhizosphere of a forage grass) were compared with regard to their effects on root hair deformation, their attachment to roots, and their effects on the growth of four wheat cultivar ... | 1984 | 16346680 |
| underexpression of ap from r-plasmids in fast-growing rhizobium species. | the presence of the plasmid rp1 in the cells of rhizobium leguminosarum strains rld1, 300, and 248, r. phaseoli 1233, r. trifolii strains t1 and 6661, and r. meliloti 4013 was found to appreciably increase bacterial resistance toward kanamycin and tetracycline but not toward ampicillin. the presence of 16 other r-plasmids in r. leguminosarum was also found to either not increase or only marginally increase bacterial resistance toward ampicillin. it appears now that underexpression of the plasmid ... | 1984 | 16346686 |
| genetic and molecular characterization of the pseudomonas plasmid pvs1. | a restriction map of the 30-kb nonconjugative pseudomonas plasmid pvs1 was constructed. derivatives of pvs1 obtained in vitro by successive deletions were used to localize on the physical map the determinant for resistance to mercuric ions (carried by transposon tn501), the gene(s) encoding sulfonamide resistance, a 1.6-kb region affecting plasmid stability and establishment in p. fluorescens atcc 13525, and a segment required for mobilization of pvs1 by plasmid rp1. the sulfonamide resistance d ... | 1984 | 6087391 |
| identification and dna sequence of fixz, a nifb-like gene from rhizobium leguminosarum. | previously, several mutants which nodulated peas but which failed to fix nitrogen were isolated following tn5 mutagenesis of prl 1ji, a symbiotic plasmid of rhizobium leguminosarum. two of these alleles, fix52::tn5 and fix137::tn5 were in a region of prl 1ji which hybridized to a probe that contained the nifa gene and the amino-terminal region of the nifb gene of klebsiella pneumoniae. the nitrogen fixation defect of the fix52::tn5 mutant strain was corrected by a 2.0kb fragment of the correspon ... | 1984 | 6091056 |
| molecular cloning and genetic organization of c4-dicarboxylate transport genes from rhizobium leguminosarum. | cosmids containing c4-dicarboxylate transport (dct) genes were identified from a gene bank of rhizobium leguminosarum dna made in the broad-host-range vector plafr1 by their ability to complement r. trifolii dct mutants. the dct genes were further characterized by subcloning, restriction site mapping, and transposon tn5 and tn7 mutageneses. three dct loci were identified within a 5.5-kilobase region of dna, in the order dcta-dctb-dctc. the results suggested that dcta encoded a structural compone ... | 1984 | 6094513 |
| transposon tn5 specifies streptomycin resistance in rhizobium spp. | transposon tn5 conferred streptomycin resistance on different strains of rhizobium meliloti, rhizobium leguminosarum, and rhizobium trifolii but not on escherichia coli. a gene (str) specifying this phenotype has been identified and localized on the physical and genetic map of tn5. it is transcribed from the promoter of neo, the gene that encodes neomycin phosphotransferase. the str gene is downstream from neo in a single transcriptional unit, as revealed by molecular cloning of different segmen ... | 1984 | 6327612 |
| identification of a rhizosphere protein encoded by the symbiotic plasmid of rhizobium leguminosarum. | a protein was identified which was made by wild-type strains of rhizobium leguminosarum but not by nodulation-deficient derivatives which had deletions of their symbiotic plasmids. the protein, which had a subunit molecular weight of ca. 24,000 ( 24k ), was found to be present in large amounts within bacteria that had been reisolated from the surface of inoculated pea roots but was not detected in bacteroids isolated from nodules. the protein could also be induced during growth of r. leguminosar ... | 1984 | 6327615 |
| molecular cloning and functional characterization of rhizobium leguminosarum structural nif-genes by site-directed transposon mutagenesis and expression in escherichia coli minicells. | in order to study the structural organization and regulation of the expression of the nitrogenase gene cluster in rhizobium leguminosarum pre we selected relevant subfragments of the sym-plasmid from clone banks by homology with r. meliloti nif-genes. site-directed tn5 mutagenesis was applied to a nif dh-specific clone and subsequently the transposon insertions were transferred back into the wild-type rhizobial genome by homologous recombination. phenotypic effects of tn5 mutations in the region ... | 1984 | 6330264 |
| development and trifoliin a-binding ability of the capsule of rhizobium trifolii. | the age-dependent lectin-binding ability of rhizobium trifolii 0403 capsular polysaccharide (cps) was examined by following the development of the capsule and its ability to interact with the white clover lectin trifoliin a. bacteria grown on agar plates for 3, 5, 7, 14, and 21 days were examined by electron microscopy and immunofluorescence microscopy with antibodies prepared against either r. trifolii 0403 cps or trifoliin a after pretreatment with the lectin. the capsule began to develop at o ... | 1984 | 6376470 |
| [degradation and utilization of 2,4-dioxohexahydro-1,3,5-triazine (dht) by soil microorganisms]. | the biodegradation and utilization of the antiphytoviral substance 2,4-dioxohexahydro-1,3,5-triazine (dht) by soil microorganisms was investigated. mixed cultures of microorganisms deriving from different soils diminish in nutrient broth the content of dht with increasing duration of culture. microorganisms from an egyptian garden soil fully degrade 10(-3) mol/1 dht in a culture without additional aeration within 28 days. also in deficient media the mixed microorganisms reduce the amount of dht, ... | 1984 | 6388190 |
| specific phases of root hair attachment in the rhizobium trifolii-clover symbiosis. | the time course and orientation of attachment of rhizobium trifolii 0403 to white clover root hairs was examined in slide cultures by light and electron microscopy. inocula were grown for 5 days on defined biii agar medium and represented the large subpopulation of fully encapsulated single cells which uniformly bind the clover lectin trifoliin a. when 10(7) cells or more were added per seedling, bacteria attached within minutes, forming randomly oriented clumps at the root hair tips. several ho ... | 1984 | 6393874 |
| natural variation in symbiotic nitrogen-fixing rhizobium and frankia spp. | a description is given of the natural variation in nitrogen-fixing rhizobium and frankia spp. strains and the ability to form root nodules on compatible host plants. arguments are given for the hypothesis that co-evolution has taken place through mutual interaction of host plants and indigenous rhizobium and frankia populations in the soil leading to most efficient symbiotic associations. the significance of root nodules as selective enrichment cultures of particular strains in natural and culti ... | 1984 | 6397130 |
| role of resistance to starvation in bacterial survival in sewage and lake water. | a study was conducted to determine the significance of starvation resistance to the ability of a species to survive in sewage and lake water. tests were conducted for periods of up to 14 days. rhizobium meliloti and one fluorescent and one nonfluorescent strain of pseudomonas were resistant to starvation because their population sizes did not fall appreciably in buffer and sterile lake water, and the first two maintained high numbers after being added to sterile sewage. cell densities of these b ... | 1984 | 6435525 |
| bacteriophage-induced acidic heteropolysaccharide lyases that convert the acidic heteropolysaccharides of rhizobium trifolii into oligosaccharide units. | acidic heteropolysaccharide lyases from lysates of phages 4s and by15 grown on rhizobium trifolii 4s and r. trifolii 0403, respectively, were used to analyze the capsular and excreted extracellular acidic polysaccharides of r. trifolii 0403. the activities of the enzymes as measured by viscometry were enhanced by the addition of calcium. the oligosaccharide products obtained by depolymerase digestion of the polysaccharides isolated from cells grown on agar plates for 5 days were isolated by gel ... | 1984 | 6501212 |
| stimulation of clover root hair infection by lectin-binding oligosaccharides from the capsular and extracellular polysaccharides of rhizobium trifolii. | a polysaccharide depolymerase isolated from the phage lysate of rhizobium trifolii 4s was used to fragment capsular polysaccharides (cps) and extracellular polysaccharides (eps) of r. trifolii 0403 into oligosaccharides. these products were analyzed for clover lectin (trifoliin a)-binding ability, effect on infection of white clover root hairs, and changes in glycosyl and noncarbohydrate composition with culture age. the oligosaccharides from cps of cultures grown on agar plates for 3, 5, and 7 ... | 1984 | 6501213 |
| dna sequence of the rhizobium leguminosarum nodulation genes nodab and c required for root hair curling. | a 3.2kb fragment of dna cloned from rhizobium leguminosarum has been shown to contain the genes necessary for the induction of root hair curling, the first observed step in the infection of leguminous plants by r. leguminosarum. the dna sequence of this region has been determined and three open reading frames were identified: genes corresponding to these open reading frames have been called noda, nodb and nodc and are transcribed in that order. mutations within the nodc gene completely blocked r ... | 1984 | 6514582 |
| electron allocation to h+ and n2 by nitrogenase in rhizobium leguminosarum bacteroids. | electron allocation to h+ and n2 by nitrogenase in intact rhizobium leguminosarum bacteroids has been studied. nitrogenase activity was measured in intact cells with succinate and oxygen substrates. when whole cell nitrogenase activity was inhibited by oxygen-limitation or by the addition of the h+-conducting ionophore carbonylcyanide m-chlorophenylhydrazone, both inducing a low intracellular atp/adp ratio, the electron allocation to h+ was favoured over that to n2. when whole cell nitrogenase a ... | 1984 | 6589160 |
| heterogeneity of rhizobium lipopolysaccharides. | the lipopolysaccharides ( lpss ) from strains of rhizobium leguminosarum, rhizobium trifolii, and rhizobium phaseoli were isolated and partially characterized by mild acid hydrolysis and by polyacrylamide gel electrophoresis. mild acid hydrolysis results in a precipitate which can be removed by centrifugation or extraction with chloroform. the supernatant contains polysaccharides which, in general, are separated into two fractions ( lps1 and lps2 ) by sephadex g-50 gel filtration chromatography. ... | 1984 | 6725208 |
| role of lectins in the specific recognition of rhizobium by lotononis bainesii. | fluorescein isothiocyanate (fitc)-labeled lectin purified from the root of lotononis bainesii baker was bound by cells of five out of seven l. bainesii-nodulating strains of rhizobium under culture conditions. with the exception of a strain of rhizobium leguminosarum, strains of noninfective rhizobia failed to bind the root lectin under these conditions. the two nonlectin binding l. bainesii-specific strains did not bind root lectin on the l. bainesii rhizoplane although this was observed with t ... | 1984 | 16663509 |
| the effect of high concentrations of glucose and fructose on the respiration rate of isolated rhizobium leguminosarum bacteroids. | the effect of high concentrations of glucose and fructose on the respiration rate of rhizobium leguminosarum bacteroids isolated from nodules of pisum sativum was investigated. high concentrations of glucose and fructose stimulated the respiration rate of the bacteroids. fructose stimulated the respiration rate to a higher extent than glucose. malate in a concentration of 1 mm increased the respiration rate of bacteroids to a high level. with bacteroids suspended in a medium with a high concentr ... | 1984 | 23195155 |
| a comparison of the surface polysaccharides from rhizobium leguminosarum 128c53 smrif with the surface polysaccharides from its exo mutant. | the surface polysaccharides of rhizobium leguminosarum 128c53 sm(r)rif(r) (parent) and its exo(-1) mutant were isolated and characterized. the parent carries out normal symbiosis with its host, pea, while the exo(-1) mutant does not nodulate the pea. the following observations were made. (a) the parent produces lipopolysaccharide (lps), typical acidic extracellular polysaccharide (eps), and three additional polysaccharides, ps1, ps2, and ps3. the ps1 and ps2 fractions are likely to be the capsul ... | 1983 | 16662808 |
| host plant cultivar effects on hydrogen evolution by rhizobium leguminosarum. | the effect of host plant cultivar on h(2) evolution by root nodules was examined in symbioses between pisum sativum l. and selected strains of rhizobium leguminosarum. hydrogen evolution from root nodules containing rhizobium represents the sum of h(2) produced by the nitrogenase enzyme complex and h(2) oxidized by any uptake hydrogenase present in those bacterial cells. relative efficiency (re) calculated as re = 1 - (h(2) evolved in air/c(2) h(2) reduced) did not vary significantly among ;felt ... | 1983 | 16663112 |
| cloning of the symbiotic region of rhizobium leguminosarum: the nodulation genes are between the nitrogenase genes and a nifa-like gene. | the region of the rhizobium leguminosarum plasmid prl1ji involved in nodulation and nitrogen fixation has been cloned on a series of four overlapping cosmid clones. these clones represent 60 kb of prl1ji dna on which a series of tn5-induced fix and nod alleles have been identified, with the two most distant alleles being separated by 45 kb of dna. the mutant alleles fell into three groups, two clusters of fix alleles separated by one cluster of nod alleles. within one group of fix alleles, dna h ... | 1983 | 16453461 |
| plasmid visualization and nif gene location in nitrogen-fixing azospirillum strains. | a modified gel electrophoresis technique provided a reproducible way of detecting and isolating plasmids with molecular weights ranging from 12 x 10(6) to 370 x 10(6) for azospirillum species. analysis with the nifhd region of rhizobium trifolii showed that the azospirillum nif genes were chromosomally located in all eight strains investigated and not on endogenous plasmids. | 1983 | 6309750 |
| sym plasmid transfer to various symbiotic mutants of rhizobium trifolii, r. leguminosarum, and r. meliloti. | two self-transmissible sym(biosis) plasmids, one encoding pea-specific nodulation and nitrogen-fixation functions (plasmid pjb5ji) and the other encoding clover-specific nodulation and nitrogen-fixation functions (plasmid pbr1an) were used to determine whether the symbiotic genes encoded on these plasmids are expressed in various members of the rhizobiaceae. the host specificity of rhizobium trifolii and r. leguminosarum sym plasmid-cured strains could be directly determined by the transfer to t ... | 1983 | 6315675 |
| symbiotic properties of c4-dicarboxylic acid transport mutants of rhizobium leguminosarum. | the transport of succinate was studied in bacteroids of an effective, streptomycin-resistant strain (gf160) of rhizobium leguminosarum. high levels of succinate transport occurred, and the kinetics, specificity, and sensitivity to metabolic inhibitors were similar to those previously described for free-living cells. the symbiotic properties of two transposon (tn5)-mediated c4-dicarboxylate transport mutants (strains gf31 and gf252) were determined. strain gf31 formed ineffective nodules, and bac ... | 1983 | 6853448 |
| identification of a rhizobium trifolii plasmid coding for nitrogen fixation and nodulation genes and its interaction with pjb5ji, a rhizobium leguminosarum plasmid. | rhizobium trifolii t37 contains at least three plasmids with sizes of greater than 250 megadaltons. southern blots of agarose gels of these plasmids probed with rhizobium meliloti nif dna indicated that the smallest plasmid, prtt37a, contains the nif genes. transfer of the rhizobium leguminosarum plasmid pjb5ji, which codes for pea nodulation and the nif genes and is genetically marked with tn5, into r. trifolii t37 generated transconjugants containing a variety of plasmid profiles. the plasmid ... | 1983 | 6630147 |
| congo red absorption by rhizobium leguminosarum. | congo red absorption is generally considered a contraindication of rhizobium. however, r. leguminosarum takes up the dye on yeast extract-mannitol agar. the uptake of congo red varies among strains of r. leguminosarum, as shown elsewhere with strains of r. trifolii and r. meliloti. congo red absorption does not distinguish rhizobia from other bacteria, but may be useful as a strain marker. | 1983 | 16346177 |
| production of antimicrobial and bacteriocin-like substances by rhizobium trifolii. | rhizobium trifolii strains iari and rel-1 produced substances with broad and narrow activity spectra, respectively. reproducible inhibitory zones of various sizes produced by r. trifolii iari (2 to 14 mm) and r. trifolii rel-1 (2 to 6 mm) were detected, depending upon the indicator organism used. the maximum production of these substances by both strains of r. trifolii was observed on l-arabinose agar. a preliminary characterization of the antimicrobial substance produced by strain iari showed r ... | 1983 | 16346202 |
| hydrogen recycling by rhizobium leguminosarum isolates and growth and nitrogen contents of pea plants (pisum sativum l.). | the ability to recycle h(2) evolved by nitrogenase is thought to be of importance in increasing the efficiency of n(2) fixation and to be a factor in increasing plant yield in symbiotic systems. to determine whether this ability is a significant factor in the rhizobium leguminosarum-pisum sativum l. system, plants were inoculated with r. leguminosarum isolates which differed in their ability to oxidize h(2) and in their relative efficiency of n(2) fixation. these plants were grown at three level ... | 1983 | 16346248 |
| competition among rhizobium leguminosarum strains for nodulation of lentils (lens esculenta). | thirty-one cultures of rhizobium leguminosarum were screened for effectiveness (c(2)h(2) reduction) on lentils (lens esculenta). fluorescent antibodies prepared against three of the most effective strains (hawaii 5-0, nitragin 92a3, and nitragin 128a12) exhibited a high degree of strain specificity; the antibodies reacted strongly with their homologous rhizobia in culture and with bacteroids in nodules. they did not cross-react with one another, and only weakly with 5 of the 47 other r. legumino ... | 1983 | 16346257 |
| interaction of agromyces ramosus with other bacteria in soil. | agromyces ramosus occurs in very high numbers in most soils and, based on studies of laboratory isolates, does not require host cells for growth. nevertheless, it attacked and destroyed most of the gram-positive and gram-negative bacterial species tested as possible host organisms. a. ramosus also attacked and destroyed saccharomyces cerevisiae. the possibility of attack on fungi was unclear. among the bacteria serving as hosts were the important soil species azotobacter vinelandii, rhizobium le ... | 1983 | 16346402 |
| effect of acidity on the composition of an indigenous soil population of rhizobium trifolii found in nodules of trifolium subterraneum l. | acidity affected which members of an indigenous soil population of rhizobium trifolii nodulated trifolium subterraneum l. cv. mt. barker. in three experiments involving plants grown either in mineral salts agar adjusted to ph 4.8 or 6.8 and inoculated with a soil suspension or grown directly in samples of unamended soil (ph 4.8) or soil amended with caco(3) (ph 6.4), 121 of 151 isolates of r. trifolii were placed into four serogroups. seventy-nine of these isolates were placed into two serogroup ... | 1983 | 16346425 |
| succinate-induced morphology of rhizobium trifolii 0403 resembles that of bacteroids in clover nodules. | morphological changes which accompany nutrient enrichment of rhizobium trifolii 0403 were studied. assays of cell number and size coupled with scanning electron microscopy and immunofluorescence microscopy showed that succinate induces cells to stop dividing in vitro and to swell either in the cell center or at one cell pole. the extent and frequency of in vitro cell swelling were in direct relation to the concentration of succinate added to the enrichment medium. the in vitro swelling of cells ... | 1982 | 16346058 |
| growth-related substituent changes in exopolysaccharides of fast-growing rhizobia. | pyruvic acid and o-acetyl groups are the major noncarbohydrate substituents in exopolysaccharides (eps) produced by fast-growing species of rhizobium. eps substituent variations were observed among strains of the same species. the amounts of these substituents also varied with culture age; pyruvic acid increased in the eps of all four species, whereas o-acetyl increased in rhizobium trifolii and r. leguminosarum eps, decreased in r. meliloti eps, and remained constant in r. phaseoli eps. the use ... | 1982 | 16346062 |
| alteration of the trifoliin a-binding capsule of rhizobium trifolii 0403 by enzymes released from clover roots. | the effect of white clover root exudate on capsules of rhizobium trifolii 0403 was examined. the clover lectin trifoliin a was detected in root exudate of two clover varieties by indirect immunofluorescence with antibody against this lectin purified from clover seed. trifoliin a bound uniformly to encapsulated, heat-fixed cells during 1 h of incubation with root exudate. after 4 to 8 h of incubation, trifoliin a was only bound to one pole of the cells. transmission electron microscopy showed tha ... | 1982 | 16346081 |
| quantitative study of nodulation competitiveness in rhizobium strains. | we compared the nodulation competitiveness of three strains of rhizobium leguminosarum by counting the number of nodules formed on faba bean plants after the application at sowing time of different concentrations of the strains to soils already containing rhizobium strains of the same species. a relationship of type y = ax was found to exist between the ratio of the nodules formed by the applied inoculum strain to the nodules formed by the soil strains and the ratio of rhizobium cells in the ino ... | 1982 | 16346089 |
| competitiveness of rhizobium trifolii strains associated with red clover (trifolium pratense l.) in mississippi soils. | five strains of rhizobium trifolii were evaluated in competition with indigenous populations in nodulating red clover (trifolium pratense l.) cv. kenland in two different soils in mississippi. double antibiotic resistance acquisition was used to measure the proportion of nodules occupied by the introduced mutant strains. in vertisol soil, strains rp113-7, 162bb1, lm1, and 162p17 were recovered in at least 94% of the assayed nodules, whereas ta1 was found in 83.8% of the nodules. at an ultisol lo ... | 1982 | 16346130 |
| the map position of sym-plasmid regions expressed in the bacterial and endosymbiotic form of rhizobium leguminosarum. | 1982 | 6179109 | |
| restriction endonuclease mapping of a rhizobium leguminosarum sym plasmid. | 1982 | 6285400 | |
| on the operon structure of the nitrogenase genes of rhizobium leguminosarum and azotobacter vinelandii. | the transcription of the nitrogenase genes in rhizobium leguminosarum was studied by analysing total cellular rna from bacteroids for the presence of nitrogenase messenger rna. the rna was separated by agarose gel electrophoresis and blotted onto nitrocellulose filters. messenger rna for nitrogenase was detected by hybridization with probes derived from plasmid psa30, a recombinant plasmid carrying the nitrogenase genes of klebsiella pneumoniae. in the same way nitrogenase mrna was detected in r ... | 1982 | 6289264 |
| use of plasmid r68.45 for constructing a circular linkage map of the rhizobium trifolii chromosome. | plasmid r68.45 was used to promote conjugal transfer of chromosomal markers in rhizobium trifolii rs55. analysis of two-factor and three-factor crosses among r. trifolii strains enabled construction of a circular linkage map of the r. trifolii chromosome, containing 17 nutritional and resistance markers. | 1982 | 6947977 |
| uptake hydrogenase activity and atp formation in rhizobium leguminosarum bacteroids. | the role of uptake hydrogenase was studied in rhizobium leguminosarum bacteroids from the nodules of pisum sativum l. cv. homesteader. uptake hydrogenase activity, measured by the 3h2 uptake method, was dependent on o-consumption and was similar to h2 uptake measured by gas chromatography. km for o2 of 0.0007 atm (0.0709 kpa) and a km for h2 of 0.0074 atm (0.7498, kpa) were determined. h2 increased the rate of endogenous respiration by isolates with uptake hydrogenase (hup+) but had no effect on ... | 1982 | 7047503 |
| regulation of tryptophan genes in rhizobium leguminosarum. | twelve tryptophan auxotrophs of rhizobium leguminosarum were characterized biochemically. they were grown in complex and minimal media with several carbon sources, in both limiting and excess tryptophan. missing enzyme activities allowed assignment of all mutant to the trpe, trpd, trpb, or trpa gene, confirming earlier results with the same mutants (johnston et al., mol. gen. genet. 165:323-330, 1978). in regulatory experiments, only the first enzyme of the pathway, anthranilate synthase, respon ... | 1982 | 7061383 |
| mechanism of regulation of glucose transport in rhizobium leguminosarum. | multiple glucose transport systems were distinguished in rhizobium leguminosarum. we found nonlinear lineweaver-burk plots for the uptake of glucose, 2-deoxy-d-glucose, and alpha-methyl-d-glucoside, and this implied the existence of at least two uptake mechanisms. different patterns of inhibition of 2-deoxy-d-glucose uptake and alpha-methyl-d-glucoside uptake at 0.1 mm by various carbohydrates revealed differences in the stereospecificities of the transport systems. osmotic shock treatment aboli ... | 1982 | 7061388 |
| genetic transformation of rhizobium leguminosarum by plasmid dna. | we demonstrated the genetic transformation of rhizobium leguminosarum by r68.45 plasmid dna by freezing and thawing cell suspensions in the presence of r68.45 plasmid dna and 20 mm mgcl2. clones resistant to kanamycin and tetracycline were recovered at a frequency of 10(-8) per recipient cell. no colonies that were doubly drug resistant were recovered in parallel control experiments. | 1982 | 7061403 |
| molecular mechanism for loss of nodulation properties of rhizobium trifolii. | of 18 rhizobium trifolii strains tested, 12 showed a high frequency of loss of nodulation ability after incubation in cultures at elevated temperatures. a correlation between loss of nodulation ability and loss of a large plasmid was demonstrated for r. trifolii. in some nonnodulating (nod-) mutants, deletions occurred instead of total elimination of the plasmid molecule. the maximum curing effect was observed in bacteria incubated at 35 degrees c. after 4 or more days of incubation at this temp ... | 1982 | 7076625 |
| identification and mobilization by cointegrate formation of a nodulation plasmid in rhizobium trifolii. | a nodulation plasmid, prtr-514a, of molecular size 180 megadaltons (mdal) was identified in rhizobium trifolii strain nzp514. this plasmid was absent in both spontaneous and heat-cured nod- derivatives of nzp514, and these strains were unable to induce root hair curling. the ability to nodulate clover was transferred from the wild-type strain to a nod- derivatives, pn104, with the broad-host-range plasmid r68.45 (39 megadaltons) at a cotransfer frequency of about 4 x 10(-3). most of the nod+ tra ... | 1982 | 7085562 |
| plasmids and stability of symbiotic properties of rhizobium trifolii. | a conjugal plasmid which encodes both peak nodulation genes and nitrogenase genes, and which is labeled with the transposon tn5, was transferred to a wild-type rhizobium trifolii strain to examine the stability and expression of the host range and fixation (fix+) phenotypes. transconjugates were isolated which were shown to initially form nitrogen-fixing nodules (nod+ fix+) on both clovers and peas. these hybrid strains were then repeatedly passaged through either pea or clover nodules or onto a ... | 1982 | 7096265 |
| properties of rhizobium leguminosarum isolated from various regions of morocco. | twenty-eight isolates of rhizobium leguminosarum capable of nodulating broad-bean (vicia faba l. var. major) were collected throughout morocco and characterized by using morphological, physiological, biochemical and serological tests. the properties of isolates from within a given climatic zone varied as much as the properties of isolates from different zones. the isolates were adapted to desiccation, but were not adapted to temperatures higher than 37 degrees c. a high degree of heterogeneity w ... | 1982 | 7103311 |
| identification of the sym plasmid of rhizobium leguminosarum strain 1001 and its transfer to and expression in other rhizobia and agrobacterium tumefaciens. | 1982 | 7146147 | |
| growth regulators, rhizobium and nodulation in peas : the cytokinin content of a wild-type and a ti-plasmid-containing strain of r. leguminosarum. | the cytokinin content of roots and nodules of pea and the culture supernatants from two strains of rhizobium leguminosarum has been examined. roots, nodules and wild-type rhizobium culture medium contained very little cytokinin as indicated by bioassay. chemical ionisation gas chromatography-mass spectrometric analysis of the isopentenyladenine content of the culture medium from the rhizobium strains confirmed that the content of the wild-type was low (approx. 1 ng dm(-3)) but that it was increa ... | 1982 | 24271872 |