| infection and invasion of roots by symbiotic, nitrogen-fixing rhizobia during nodulation of temperate legumes. | bacteria belonging to the genera rhizobium, mesorhizobium, sinorhizobium, bradyrhizobium, and azorhizobium (collectively referred to as rhizobia) grow in the soil as free-living organisms but can also live as nitrogen-fixing symbionts inside root nodule cells of legume plants. the interactions between several rhizobial species and their host plants have become models for this type of nitrogen-fixing symbiosis. temperate legumes such as alfalfa, pea, and vetch form indeterminate nodules that aris ... | 2004 | 15187185 |
| integrative plasmid vector for constructing single-copy reporter systems to study gene regulation in rhizobium meliloti and related species. | the integrative system of phage 16-3 of rhizobium meliloti 41 was shown to function in several bacterial species belonging to the rhizobium, bradyrhizobium, azorhizobium, and agrobacterium genera. it might also function in many other bacterial species provided that both the target site (attb) and the required host factor(s) are present. here we report on the construction of a new integrative vector that can be utilized in gene regulation studies. it provides an opportunity to create a single-cop ... | 2004 | 15212892 |
| membrane association of klebsiella pneumoniae nifl is affected by molecular oxygen and combined nitrogen. | in the diazotroph klebsiella pneumoniae, nifl and nifa regulate transcription of the nitrogen fixation genes in response to molecular oxygen and combined nitrogen. we recently showed that fnr is the primary oxygen sensor. fnr transduces the oxygen signal towards the negative regulator nifl by activating genes whose products reduce the fad moiety of nifl under anoxic conditions. these fnr-dependent gene products could be membrane-bound components of the anaerobic electron transport chain. consequ ... | 2002 | 11907678 |
| azide-resistant mutants of azorhizobium caulinodans with enhanced symbiotic effectiveness. | azide-resistant mutants of azorhizobium caulinodans strains sb3, s78, srr13 and srs8 were isolated and screened for nitrate reductase activity. selected nitrate reductase negative mutants were inoculated on sesbania bispinosa and s. rostrata under sterile conditions in chillum jars to study their symbiotic behavior. azide-resistant mutants exhibited either similar or higher symbiotic effectiveness than the parent strain after 30 d of plant growth. nodule mass, nitrogenase activity and uptake hyd ... | 2001 | 11702406 |
| molecular and functional characterization of the azorhizobium caulinodans ors571 hydrogenase gene cluster. | in this work, we report the cloning and sequencing of the azorhizobium caulinodans ors571 hydrogenase gene cluster. sequence analysis revealed the presence of 20 open reading frames huptuvhypfhupslcdfghjk hypabhuprhypcdehupe. the physical and genetic organization of a. caulinodans ors571 hydrogenase system suggests a close relatedness to that of rhodobacter capsulatus. in contrast to the latter species, a gene homologous to rhizobium leguminosarum hupe was identified downstream of the hyp operon ... | 2004 | 15321689 |
| regulation of glnk activity: modification, membrane sequestration and proteolysis as regulatory principles in the network of nitrogen control in corynebacterium glutamicum. | p(ii)-type signal transduction proteins play a central role in nitrogen regulation in many bacteria. in response to the intracellular nitrogen status, these proteins are rendered in their function and interaction with other proteins by modification/demodification events, e.g. by phosphorylation or uridylylation. in this study, we show that glnk, the only p(ii)-type protein in corynebacterium glutamicum, is adenylylated in response to nitrogen starvation and deadenylylated when the nitrogen suppl ... | 2004 | 15458411 |
| diversity in a promiscuous group of rhizobia from three sesbania spp. colonizing ecologically distinct habitats of the semi-arid delhi region. | sesbania-rhizobia associations have immense significance in soil amelioration programs for diverse habitats. diversity in symbiotic properties, lps profiles, sym plasmid and rhizobiophage sensitivity of 28 root- and stem-nodulating bacterial isolates of three sesbania species (s. sesban, s. aegyptica and s. rostrata) inhabiting six ecologically distinct sites of semi-arid delhi region was analyzed. the isolates were highly promiscuous among the symbiotic partners (sesbania spp.). the root nodule ... | 2005 | 15636748 |
| biodiversity of uptake hydrogenase systems from legume endosymbiotic bacteria. | uptake hydrogenases in legume endosymbiotic bacteria recycle hydrogen produced during the nitrogen fixation process in legume nodules. despite the described beneficial effect on plant productivity, the hydrogen oxidation capability is not widespread in the rhizobiaceae family. characterization of hydrogenase gene clusters in strains belonging to rhizobium, bradyrhizobium and azorhizobium reveals a similar overall genetic organization along with important differences in gene regulation. in additi ... | 2005 | 15667257 |
| complex formation between amtb and glnk: an ancestral role in prokaryotic nitrogen control. | ammonium transport proteins belonging to the amt family are ubiquitous in prokaryotes. in escherichia coli, the amtb protein and the associated p(ii) signal transduction protein (glnk) have recently been recognized as an ammonium sensory system that effectively couples the intracellular nitrogen regulation (ntr) system to external changes in ammonium availability. given the almost invariant coupling of amtb and glnk in bacteria and archaea it seems probable that these two proteins may constitute ... | 2005 | 15667297 |
| lipopolysaccharides as a communication signal for progression of legume endosymbiosis. | establishment of a successful symbiosis between rhizobia and legumes results from an elaborate molecular dialogue between both partners. bacterial nodulation (nod) factors are indispensable for initiating plant responses, whereas bacterial surface polysaccharides are important for infection progression and nodule development. the mutant ors571-oac2 of azorhizobium caulinodans, affected in its surface polysaccharides, provokes a defective interaction with its host sesbania rostrata. ors571-oac2 i ... | 2005 | 15699329 |
| identification and active expression of the mycobacterium tuberculosis gene encoding 5-phospho-{alpha}-d-ribose-1-diphosphate: decaprenyl-phosphate 5-phosphoribosyltransferase, the first enzyme committed to decaprenylphosphoryl-d-arabinose synthesis. | decaprenylphosphoryl-d-arabinose, the lipid donor of mycobacterial d-arabinofuranosyl residues, is synthesized from phosphoribose diphosphate rather than from a sugar nucleotide. the first committed step in the process is the transfer of a 5-phosphoribosyl residue from phosphoribose diphosphate to decaprenyl phosphate to form decaprenylphosphoryl-5-phosphoribose via a 5-phospho-alpha-d-ribose-1-diphosphate:decaprenyl-phosphate 5-phospho-ribosyltransferase. a candidate for the gene encoding this ... | 2005 | 15878857 |
| the hierarchical system of the 'alphaproteobacteria': description of hyphomonadaceae fam. nov., xanthobacteraceae fam. nov. and erythrobacteraceae fam. nov. | phylogenetic analysis of the class 'alphaproteobacteria', including physiologically diverse species, was conducted by using small-subunit rrna gene sequences. the 16s rrna gene sequences of 261 species in the class 'alphaproteobacteria' were obtained from genbank/embl/ddbj for constructing a phylogenetic tree by using maximum-likelihood analysis. in the resulting tree, members of the class 'alphaproteobacteria' were subdivided into five major clusters, which were compared with the taxonomic outl ... | 2005 | 16166687 |
| regulation of amtr-controlled gene expression in corynebacterium glutamicum: mechanism and characterization of the amtr regulon. | amtr, the master regulator of nitrogen control in corynebacterium glutamicum, represses transcription of a number of genes during nitrogen surplus. repression is released by an interaction of amtr with signal transduction protein glnk. as shown by pull-down assays and gel retardation experiments, only adenylylated glnk, which is present in the cells during nitrogen limitation, is able to bind to amtr. the amtr regulon was characterized in this study by a combination of bioinformatics, transcript ... | 2005 | 16194241 |
| gibberellins are involved in nodulation of sesbania rostrata. | upon submergence, azorhizobium caulinodans infects the semiaquatic legume sesbania rostrata via the intercellular crack entry process, resulting in lateral root-based nodules. a gene encoding a gibberellin (ga) 20-oxidase, srga20ox1, involved in ga biosynthesis, was transiently up-regulated during lateral root base nodulation. two srga20ox1 expression patterns were identified, one related to intercellular infection and a second observed in nodule meristem descendants. the infection-related expre ... | 2005 | 16258018 |
| nitrogen-fixing nodules from rose wood legume trees (dalbergia spp.) endemic to madagascar host seven different genera belonging to alpha- and beta-proteobacteria. | although legume biodiversity is concentrated in tropical regions, the majority of studies on legume nodulating bacteria (lnb) are focused on cultivated leguminous plants from temperate regions. however, recent works on tropical regions tend to indicate that the actual diversity of lnb is largely underestimated. in this study, we report the isolation and characterization of 68 nitrogen-fixing root nodule bacteria collected from eight endemic tree species of dalbergia in madagascar. the isolates w ... | 2005 | 16262864 |
| decaprenylphosphoryl arabinofuranose, the donor of the d-arabinofuranosyl residues of mycobacterial arabinan, is formed via a two-step epimerization of decaprenylphosphoryl ribose. | the major cell wall polysaccharide of mycobacteria is a branched-chain arabinogalactan in which arabinan chains are attached to the 5 carbon of some of the 6-linked galactofuranose residues; these arabinan chains are composed exclusively of d-arabinofuranose (araf) residues. the immediate precursor of the polymerized araf is decaprenylphosphoryl-d-araf, which is derived from 5-phosphoribose 1-diphosphate (prpp) in an undefined manner. on the basis of time course, feedback, and chemical reduction ... | 2005 | 16291675 |
| responses of azorhizobium caulinodans to cadmium stress. | the symbiosis of azorhizobium caulinodans and an annul legume sesbania rostrata was recently found to be tolerant to cadmium pollution by an unknown mechanism. in this study, a. caulinodans ors571 and zy-20 showed much stronger tolerance to cadmium than a mutant ors571-x15 and a common rhizobium sp., with minimum inhibitory concentration values as high as 4 and 5 mm (versus 1 and 0.1 mm) on yeast extract mannitol agar medium, respectively. although cd uptake by all three strains of a. caulinodan ... | 2005 | 16332342 |
| survival of azorhizobium caulinodans in the soil and rhizosphere of wetland rice under sesbania rostrata-rice rotation. | the survival of indigenous and introduced strains of azorhizobium caulinodans in flooded soil and in the rice rhizosphere, where in situ sesbania rostrata was incorporated before the rice crop, is reported. the azorhizobia studied were both root and stem nodulating. in a pot experiment, two crop cycles each of inoculated and noninoculated sesbania-rice were compared with two crop cycles of flooded fallow-rice. in a field experiment, the effect of repeated incorporation of in situ s. rostrata in ... | 1989 | 16347853 |
| epiphytic occurrence of azorhizobium caulinodans and other rhizobia on host and nonhost legumes. | a large population of azorhizobium caulinodans was present on sesbania rostrata; up to 5 x 10 cm were found on leaves and fewer were found on flowers. although a. caulinodans was also present on the leaves of sesbania aculeata (nonhost), the populations were much smaller than that observed on s. rostrata. the population of s. aculeata rhizobia on host leaves was less than 30 cm, and their presence on host flowers was sporadic. aeschynomene afraspera and aeschynomene aspera rhizobia, which are pr ... | 1989 | 16348019 |
| epiphytic occurrence of azorhizobium caulinodans and other rhizobia on host and nonhost legumes. | [this corrects the article on p. 2407 in vol. 55.]. | 1989 | 16348065 |
| oxygen uptake and hydrogen-stimulated nitrogenase activity from azorhizobium caulinodans ors571 grown in a succinate-limited chemostat. | succinate-limited continuous cultures of an azorhizobium caulinodans strain were grown on ammonia or nitrogen gas as a nitrogen source. ammonia-grown cells became oxygen limited at 1.7 mum dissolved oxygen, whereas nitrogen-fixing cells remained succinate limited even at dissolved oxygen concentrations as low as 0.9 mum. nitrogen-fixing cells tolerated dissolved oxygen concentrations as high as 41 mum. succinate-dependent oxygen uptake rates of cells from the different steady states ranged from ... | 1991 | 16348585 |
| nitrogen fixation and hydrogen metabolism in relation to the dissolved oxygen tension in chemostat cultures of the wild type and a hydrogenase-negative mutant of azorhizobium caulinodans. | both the wild type and an isogenic hydrogenase-negative mutant of azorhizobium caulinodans growing ex planta on n(2) as the n source were studied in succinate-limited steady-state chemostat cultures under 0.2 to 3.0% dissolved o(2) tension. production or consumption of o(2), h(2), and co(2) was measured with an on-line-connected mass spectrometer. in the range of 0.2 to 3.0%, growth of both the wild type and the mutant was equally dependent on the dissolved o(2) tension: the growth yield decreas ... | 1994 | 16349280 |
| chemo-enzymatic synthesis of allyl penta-n-acetyl-chitopentaose. | cell density cultivation of recombinant escherichia coli strains harboring the nodc gene (encoding chitooligosaccharide synthase) from azorhizobium caulinodans has been previously described as a practical method for the preparation of gram-scale quantities of penta-n-acetyl-chitopentaose. we have now extended this method to the production of allylated derivative of penta-n-acetyl-chitopentaose by using allyl 2-acetamido-2-deoxy-beta-d-glucopyranoside (2) as the initial acceptor for the synthesis ... | 2006 | 16403625 |
| molecular phylogeny based on the 16s rrna gene of elite rhizobial strains used in brazilian commercial inoculants. | nitrogen is often a limiting nutrient, therefore the sustainability of food crops, forages and green manure legumes is mainly associated with their ability to establish symbiotic associations with stem and root-nodulating n2-fixing rhizobia. the selection, identification and maintenance of elite strains for each host are critical. decades of research in brazil resulted in a list of strains officially recommended for several legumes, but their genetic diversity is poorly known. this study aimed a ... | 2006 | 16442259 |
| rhizobial exopolysaccharides: genetic control and symbiotic functions. | specific complex interactions between soil bacteria belonging to rhizobium, sinorhizobium, mesorhizobium, phylorhizobium, bradyrhizobium and azorhizobium commonly known as rhizobia, and their host leguminous plants result in development of root nodules. nodules are new organs that consist mainly of plant cells infected with bacteroids that provide the host plant with fixed nitrogen. proper nodule development requires the synthesis and perception of signal molecules such as lipochitooligosacchari ... | 2006 | 16483356 |
| ameba-associated microorganisms and diagnosis of nosocomial pneumonia. | to elucidate the role of ameba-associated microorganisms (aams) as etiologic agents of pneumonia, we screened for legionella spp., parachlamydia acanthamoeba, afipia sp., bosea spp., bradyrhizobium spp., mesorhizobium amorphae, rasbo bacterium, azorhizobium caulinodans, acanthamoeba polyphaga mimivirus, and conventional microorganisms in 210 pneumonia patients in intensive-care units by using culture, polymerase chain reaction, and serologic testing. these resulted in 59 diagnoses in 40 patients ... | 2006 | 16494750 |
| metabolic changes of rhizobia in legume nodules. | bacteria have evolved a wide variety of metabolic strategies to cope with varied environments. some are specialists and only able to survive in restricted environments; others are generalists and able to cope with diverse environmental conditions. rhizobia (e.g. rhizobium, sinorhizobium, bradyrhizobium, mesorhizobium and azorhizobium species) can survive and compete for nutrients in soil and the plant rhizosphere but can also form a beneficial symbiosis with legumes in a highly specialized plant ... | 2006 | 16520035 |
| diversity of bacteria contaminating paper machines. | formation of microbial biofilms and slimes is a general and serious problem in the operation of paper machines. studies of microbial populations in paper machine-derived biofilms have been conducted using standard microbiological procedures; however, the bacterial genera present in this type of samples as well as their diversity are quite poorly known. here, the bacterial diversity of 38 process water and 22 biofilm samples from four different finnish paper machines were analyzed by length heter ... | 2006 | 16520979 |
| the sesbania root symbionts sinorhizobium saheli and s. teranga bv. sesbaniae can form stem nodules on sesbania rostrata, although they are less adapted to stem nodulation than azorhizobium caulinodans. | sesbania species can establish symbiotic interactions with rhizobia from two taxonomically distant genera, including the sesbania rostrata stem-nodulating azorhizobium sp. and azorhizobium caulinodans and the newly described sinorhizobium saheli and sinorhizobium teranga bv. sesbaniae, isolated from the roots of various sesbania species. a collection of strains from both groups were analyzed for their symbiotic properties with different sesbania species. s. saheli and s. teranga bv. sesbaniae st ... | 1997 | 16535538 |
| azorhizobium doebereinerae sp. nov. microsymbiont of sesbania virgata (caz.) pers. | thirty-four rhizobium strains were isolated from root nodules of the fast-growing woody native species sesbania virgata in different regions of southeast brazil (minas gerais and rio de janeiro states). these isolates had cultural characteristics on yma quite similar to azorhizobium caulinodans (alkalinization, scant extracellular polysaccharide production, fast or intermediate growth rate). they exhibited a high similarity of phenotypic and genotypic characteristics among themselves and to a le ... | 2006 | 16564956 |
| the ntrc gene of agrobacterium tumefaciens c58 controls glutamine synthetase (gsii) activity, growth on nitrate and chromosomal but not ti-encoded arginine catabolism pathways. | the ntrc locus of agrobacterium tumefaciens c58 has been cloned using the azorhizobium sesbaniae ors571 ntrc gene as a dna hybridization probe. transposon tn5 mutagenesis of the cloned ntrc locus was carried out and one tn5 insertion within the region of highest dna homology with a. sesbaniae ors571 ntrc was used for gene replacement of the wild-type c58 ntrc gene. the a. tumefaciens ntrc::tn5 mutant was found to be unable to grow on nitrate as sole nitrogen (n) source, to lack glutamine synthet ... | 1987 | 17193704 |
| evaluation of nutrient limitation in aquatic ecosystems with nitrogen fixing bacteria. | there has always been a great need for simple and accurate bioassays for evaluating nutrient limitation in aquatic ecosystems. whereas organic carbon is usually considered to be the limiting nutrient for microbial growth in many aquatic ecosystems, there are, however, many water sources that are limited by phosphorus or nitrogen. a method named "nitrogen fixing bacterial growth potential" (nfbgp) test, which is based on pre-culturing of autochthonous (target) microorganisms was described. the me ... | 2006 | 17294653 |
| nod factor perception during infection thread growth fine-tunes nodulation. | bacterial nodulation factors (nfs) are essential signaling molecules for the initiation of a nitrogen-fixing symbiosis in legumes. nfs are perceived by the plant and trigger both local and distant responses, such as curling of root hairs and cortical cell divisions. in addition to their requirement at the start, nfs are produced by bacteria that reside within infection threads. to analyze the role of nfs at later infection stages, several phases of nodulation were studied by detailed light and e ... | 2007 | 17313164 |
| a symbiotic plant peroxidase involved in bacterial invasion of the tropical legume sesbania rostrata. | aquatic nodulation on the tropical legume sesbania rostrata occurs at lateral root bases via intercellular crack-entry invasion. a gene was identified (srprx1) that is transiently up-regulated during the nodulation process and codes for a functional class iii plant peroxidase. the expression strictly depended on bacterial nodulation factors (nfs) and could be modulated by hydrogen peroxide, a downstream signal for crack-entry invasion. expression was not induced after wounding or pathogen attack ... | 2007 | 17384158 |
| production and chitinase-binding ability of lipo-chitopentaose nodulation factor. | the penta-n-acetyl-chitopentaose 2 has been prepared by using recombinant e. coli strains harboring the nodc gene (encoding chitooligosaccharide synthase) from azorhizobium caulinodans. then, the deacetylase nodb removed the n-acetyl moiety from the nonreducing terminus of 2 to give tetra-n-acetyl-chitopentaose 3. n-acylation of 3 with stearyl chloride was performed in dmf containing water and provided the corresponding lipo-chitopentaose nodulation factor 4. a binding chitinase assay indicated ... | 2007 | 17518353 |
| comparative transcriptome analysis reveals common and specific tags for root hair and crack-entry invasion in sesbania rostrata. | the tropical legume sesbania rostrata provides its microsymbiont azorhizobium caulinodans with versatile invasion strategies to allow nodule formation in temporarily flooded habitats. in aerated soils, the bacteria enter via the root hair curling mechanism. submergence prevents this epidermal invasion by accumulation of inhibiting concentrations of ethylene and, under these conditions, the bacterial colonization occurs via intercellular cortical infection at lateral root bases. the transcriptome ... | 2007 | 17600136 |
| evidence for functional differentiation of duplicated nifh genes in azorhizobium caulinodans. | azorhizobium caulinodans is a symbiotic diazotroph that contains duplicated nifh genes. this study focused on the biological sense behind the duplication. in-frame deletion mutants of nifh1 and nifh2 were constructed in order to analyze nitrogen fixation activity, both in symbiosis and in free-living conditions. symbiotic nitrogen fixation activity was not affected by deletion of nifh1 or nifh2, while free-living nitrogen fixation activity was significantly decreased. deletion of nifh1 had a sig ... | 2007 | 17651409 |
| rhizobial factors required for stem nodule maturation and maintenance in sesbania rostrata-azorhizobium caulinodans ors571 symbiosis. | the molecular and physiological mechanisms behind the maturation and maintenance of n(2)-fixing nodules during development of symbiosis between rhizobia and legumes still remain unclear, although the early events of symbiosis are relatively well understood. azorhizobium caulinodans ors571 is a microsymbiont of the tropical legume sesbania rostrata, forming n(2)-fixing nodules not only on the roots but also on the stems. in this study, 10,080 transposon-inserted mutants of a. caulinodans ors571 w ... | 2007 | 17720818 |
| phage specificity and lipopolysaccarides of stem- and root-nodulating bacteria (azorhizobium caulinodans, sinorhizobium spp., and rhizobium spp.) of sesbania spp. | phage susceptibility pattern and its correlation with lipopolysaccharide (lps) and plasmid profiles may help in understanding the phenotypic and genotypic diversity among highly promiscuous group of rhizobia nodulating sesbania spp.; 43 phages were from two stem-nodulating bacteria of s. rostrata and 16 phages were from root-nodulating bacteria of s. sesban, s. aegyptica and s. rostrata. phage susceptibility pattern of 38 sesbania nodulating bacteria was correlated with their lps rather than pla ... | 2008 | 17989956 |
| induction of endophytic colonization in rice (oryza sativa l.) tissue culture plants by azorhizobium caulinodans. | endophytic colonization in rice was induced using rhizobia. dehusked seeds of rice hybrid, corh2, were used as explants for induction of calli. ms medium was modified with 2,4-d (2.5 mg l(-1)) and kinetin (0.2 mg l(-1)) for callus induction. well-developed calli were inoculated with azorhizobium caulinodans strains ors 571 and aa-sk-5 by means of imbibition. all treated calli had significant increases in protein content, total nitrogen and nitrogenase activity. imbibition of ors 571 had signific ... | 2008 | 18379880 |
| the genome of the versatile nitrogen fixer azorhizobium caulinodans ors571. | biological nitrogen fixation is a prokaryotic process that plays an essential role in the global nitrogen cycle. azorhizobium caulinodans ors571 has the dual capacity to fix nitrogen both as free-living organism and in a symbiotic interaction with sesbania rostrata. the host is a fast-growing, submergence-tolerant tropical legume on which a. caulinodans can efficiently induce nodule formation on the root system and on adventitious rootlets located on the stem. | 2008 | 18522759 |
| an outer membrane autotransporter, aoaa, of azorhizobium caulinodans is required for sustaining high n2-fixing activity of stem nodules. | in this study, we investigated the function of a putative high-molecular-weight outer membrane protein, azorhizobial outer membrane autotransporter a (aoaa), of azorhizobium caulinodans ors571. sequence analysis revealed that aoaa was an autotransporter protein belonging to the type v protein secretion system. azorhizobium caulinodans forms n(2)-fixing nodules on the stems and roots of sesbania rostrata. the sizes of stem nodules formed by an aoaa mutant having transposon insertion within this o ... | 2008 | 18557786 |
| a novel endo-hydrogenase activity recycles hydrogen produced by nitrogen fixation. | nitrogen (n(2)) fixation also yields hydrogen (h(2)) at 1:1 stoichiometric amounts. in aerobic diazotrophic (able to grow on n(2) as sole n-source) bacteria, orthodox respiratory hupsl-encoded hydrogenase activity, associated with the cell membrane but facing the periplasm (exo-hydrogenase), has nevertheless been presumed responsible for recycling such endogenous hydrogen. | 2009 | 19277114 |
| genetic diversity and distribution of bradyrhizobium and azorhizobium strains associated with the herb legume zornia glochidiata sampled from across senegal. | herb legumes have great potential for rehabilitation of semi-arid degraded soils in sahelian ecosystems as they establish mutualistic symbiosis with n(2)-fixing rhizobia. a phylogenetic analysis was performed for 78 root nodule bacteria associated with the common sahelian herb legume zornia glochidiata reichb ex dc in senegal. based on its (rdna16s-23s) and reca sequences, these strains were shown to belong to the two genera bradyrhizobium and azorhizobium. strains of this latter, although frequ ... | 2009 | 19493641 |
| comparative genome-wide transcriptional profiling of azorhizobium caulinodans ors571 grown under free-living and symbiotic conditions. | the whole-genome sequence of the endosymbiotic bacterium azorhizobium caulinodans ors571, which forms nitrogen-fixing nodules on the stems and roots of sesbania rostrata, was recently determined. the sizes of the genome and symbiosis island are 5.4 mb and 86.7 kb, respectively, and these sizes are the smallest among the sequenced rhizobia. in the present study, a whole-genome microarray of a. caulinodans was constructed, and transcriptomic analyses were performed on free-living cells grown in ri ... | 2009 | 19542345 |
| nodulation of sesbania species by rhizobium (agrobacterium) strain irbg74 and other rhizobia. | concatenated sequence analysis with 16s rrna, rpob and fusa genes identified a bacterial strain (irbg74) isolated from root nodules of the aquatic legume sesbania cannabina as a close relative of the plant pathogen rhizobium radiobacter (syn. agrobacterium tumefaciens). however, dna:dna hybridization with r. radiobacter, r. rubi, r. vitis and r. huautlense gave only 44%, 5%, 8% and 8% similarity respectively, suggesting that irbg74 is potentially a new species. additionally, it contained no vir ... | 2009 | 19555380 |
| enhanced adaptability of sesbania rostrata to pb/zn tailings via stem nodulation. | sesbania rostrata is wellknown for its stem nodulation, but the roles of stem nodulation in root nodulation and adaptation of s. rostrata to pb/zn-enriched tailings environment has been poorly understood. we investigated the effects of inoculating (with stem nodule treatment) and non-inoculating (without stem nodule treatment) azorhizobium caulinodans on the growth, root nodulation, and n fixation of s. rostrata grown on three different types of soil substrata: pb/zn tailings, garden soil amende ... | 2009 | 19862929 |
| [identification and functional characterization of genes induced by seed exudates in azorhizobium caulinodans ors571]. | to identify genes induced by plant seed exudates in azorhizobium caulinodans ors571. | 2009 | 20030054 |
| phrr-like gene prar of azorhizobium caulinodans ors571 is essential for symbiosis with sesbania rostrata and is involved in expression of reb genes. | this study focuses on the function of the gene prar that encodes a putative transcription factor in azorhizobium caulinodans ors571, a microsymbiont of sesbania rostrata. the prar gene is a homolog of the phrr gene of sinorhizobium medicae wsm419, and the prar and phrr homologs are distributed throughout the class alphaproteobacteria. the growth and nitrogen fixation activity of an a. caulinodans prar deletion mutant in the free-living state were not significantly different from those of the wil ... | 2010 | 20382809 |
| bathy phytochromes in rhizobial soil bacteria. | phytochromes are biliprotein photoreceptors that are found in plants, bacteria, and fungi. prototypical phytochromes have a pr ground state that absorbs in the red spectral range and is converted by light into the pfr form, which absorbs longer-wavelength, far-red light. recently, some bacterial phytochromes have been described that undergo dark conversion of pr to pfr and thus have a pfr ground state. we show here that such so-called bathy phytochromes are widely distributed among bacteria that ... | 2010 | 20675484 |
| symbiotic legume nodules employ both rhizobial exo- and endo-hydrogenases to recycle hydrogen produced by nitrogen fixation. | in symbiotic legume nodules, endosymbiotic rhizobia (bacteroids) fix atmospheric n(2), an atp-dependent catalytic process yielding stoichiometric ammonium and hydrogen gas (h(2)). while in most legume nodules this h(2) is quantitatively evolved, which loss drains metabolic energy, certain bacteroid strains employ uptake hydrogenase activity and thus evolve little or no h(2). rather, endogenous h(2) is efficiently respired at the expense of o(2), driving oxidative phosphorylation, recouping atp u ... | 2010 | 20838423 |
| electrokinetic remediation and microbial community shift of β-cyclodextrin-dissolved petroleum hydrocarbon-contaminated soil. | electrokinetic (ek) migration of β-cyclodextrin (β-cd), which is inclusive of total petroleum hydrocarbon (tph), is an economically beneficial and environmentally friendly remediation process for oil-contaminated soils. remediation studies of oil-contaminated soils generally prepared samples using particular tphs. this study investigates the removal of tphs from, and electromigration of microbial cells in field samples via ek remediation. both tph content and soil respiration declined after the ... | 2010 | 21052991 |
| azorhirobial chromosome partition gene (para) is involved in the onset of bacteroid differentiation in sesbania rostrata stem-nodule development. | a para gene in-frame deletion mutant of azorhizobium caulinodans ors571 (ors571-δpara) was constructed to evaluate the roles of the chromosome partitioning gene on various bacterial traits and on the development of stem-positioned nodules. the δpara mutant showed a pleiomorphic cell shape phenotype, and was polyploidy with differences in nucleoid sizes due to dramatic defects in chromosome partitioning. upon inoculating the δpara mutant onto the stem of sesbania rostrata, three types of immature ... | 2011 | 21571889 |
| identification of hammerhead ribozymes in all domains of life reveals novel structural variations. | hammerhead ribozymes are small self-cleaving rnas that promote strand scission by internal phosphoester transfer. comparative sequence analysis was used to identify numerous additional representatives of this ribozyme class than were previously known, including the first representatives in fungi and archaea. moreover, we have uncovered the first natural examples of "type ii" hammerheads, and our findings reveal that this permuted form occurs in bacteria as frequently as type i and iii architectu ... | 2011 | 21573207 |
| variations in outer-membrane characteristics of two stem-nodulating bacteria of sesbania rostrata and its role in tolerance towards diverse stress. | outer-membrane characteristics may determine the survivability of rhizobia under diverse abiotic and biotic stresses. therefore, the role of lipopolysaccharides (lps) and membrane proteins of two stem-nodulating bacteria of sesbania rostrata (azorhizobium caulinodans ors571 and rhizobium sp. we7) in determining tolerance towards abiotic and biotic stresses (hydrophobics and phages) was investigated. outer-membrane characteristics (lps and membrane-protein profiles) of ors571, we7 and thirteen st ... | 2011 | 21573832 |
| tonb-dependent receptors in nitrogen-fixing nodulating bacteria. | tonb-dependent receptors (tbdrs) allow gram-negative bacteria to uptake scarce resources from competitive environments with very high affinity. early reports on tbdrs focused on the uptake of siderophore-iron complexes but recent studies have showed that the spectrum of ligands includes sugars, vitamins, heme, and other non-ferrous cations. to investigate the possible roles of tbdrs in nitrogen-fixing, nodulating bacteria, a bioinformatics approach was adopted to identify their presence in the g ... | 2010 | 21576856 |
| characterization of cyclic ╬▓-glucans of bradyrhizobium by maldi-tof mass spectrometry. | periplasmic, cyclic ╬▓-glucans isolated from bradyrhizobium elkanii, bradyrhizobium liaoningense, and bradyrhizobium yuanmingense strains have been investigated by means of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (maldi-tof ms), 1d and 2d nuclear magnetic resonance (nmr), as well as standard chemical methods. these compounds are built of 10-13 d-glucose residues. the main fractions contain molecules assembled of 12 hexose units (m(w)=1945.363da). glucose mono ... | 2011 | 21665197 |