Publications
| Title | Abstract | Year(sorted ascending) Filter | PMID Filter |
|---|
| isolation and cloning of a azospirillum lipoferum locus that complements escherichia coli prou mutant. | glycine betaine relieved sodium chloride-mediated inhibition of growth in azospirillum lipoferum atcc 29708. 35s-methionine labelling of proteins after salinity up-shock revealed strong induction of a 30 kda protein which cross-reacted with the anti-glycine betaine binding protein antibody from escherichia coli. this suggested that a. lipoferum had a salinity-induced prou-like high-affinity glycine betaine transport system. a genomic library of a. lipoferum atcc 29708 was screened for the prou-l ... | 1998 | 9627959 |
| [immunochemical analysis of o-specific polysaccharides from the soil nitrogen-fixing bacteria azospirillum brasilense]. | immunochemical reactivity of o-specific polysaccharide and the monosaccharide composition of o-antigenic determinants of the lipopolysaccharide isolated from the type strain sp7 of azospirillum brasilense were studied. an original modification of the method of spectroturbidimetry for disperse biological systems and a nonstandard procedure for the preparation of monospecific antibodies against cell surface antigens were used. the polysaccharide fraction, which contained residues of galactose, rha ... | 1998 | 10234653 |
| the anti-sigma factors. | a mechanism for regulating gene expression at the level of transcription utilizes an antagonist of the sigma transcription factor known as the anti-sigma (anti-sigma) factor. the cytoplasmic class of anti-sigma factors has been well characterized. the class includes asia form bacteriophage t4, which inhibits escherichia coli sigma 70; flgm, present in both gram-positive and gram-negative bacteria, which inhibits the flagella sigma factor sigma 28; spoiiab, which inhibits the sporulation-specific ... | 1998 | 9891799 |
| purification and binding analysis of the nitrogen fixation regulatory nifa protein from azospirillum brasilense. | nifa protein activates transcription of nitrogen fixation operons by the alternative sigma 54 holoenzyme form of rna polymerase. this protein binds to a well-defined upstream activator sequence (uas) located at the -200/-100 position of nif promoters with the consensus motif tgt-n10-aca. nifa of azospirillum brasilense was purified in the form of a glutathione-s-transferase (gst)-nifa fusion protein and proteolytic release of gst yielded inactive and partially soluble nifa. however, the purified ... | 1998 | 9921270 |
| novel classes of azospirillum brasilense mutants with defects in the assembly and functioning of polar and lateral flagella. | azospirillum brasilense sp245 has a mixed type of flagellation: a single polar flagellum (fla) is synthesized constitutively, and abundant lateral flagella (laf) are produced only in solid and semisolid media. in the present study, omegon-km fla-laf-, fla-laf+, fla-/mot-laf-. fla-/mot-laf+, mot-laf-, and che- mutants of sp245 were constructed in vivo. in some of the mutants, a number of cells possessed from 1 to 5 subpolar long flagella (sfl). these sfl provided the host cells with unusual motil ... | 1998 | 9987751 |
| duplication of insertion element is50 associated with tn5 transposition in azospirillum brasilense. | the characterization of a dna fragment with a tn5 insertion in a regulatory nif gene of azospirillum brasilense is reported. restriction endonuclease mapping, southern hybridization with a tn5 probe, and nucleotide sequencing revealed that is50 had duplicated in tn5. the duplication of an is50 element suggests the occurrence of a replicative mechanism of transposition. a strategy, based on the bacterial ability of homologous recombination that was used to precisely eliminate tn5 along with the d ... | 1998 | 10030007 |
| bi-functional gfp- and gusa-containing mini-tn5 transposon derivatives for combined gene expression and bacterial localization studies. | the gfp gene, encoding the green fluorescent protein, was combined with the gusa gene, coding for the beta-glucuronidase enzyme, in mini-tn5 transposon derivatives for use in gram-negative bacteria. these mini-tn5 elements allow simultaneously monitoring of gene expression and localization of the marked bacteria. introduction of the resultant mini-tn5 transposons into rhizobium etli, azospirillum brasilense and pseudomonas stutzeri allowed us to visualise the interaction of these bacteria with t ... | 1999 | 10076635 |
| biosynthesis of indole-3-acetic acid in azospirillum brasilense. insights from quantum chemistry. | quantum chemical methods am1 and pm3 and chromatographic methods were used to qualitatively characterize pathways of bacterial production of indole-3-acetic acid (iaa). the standard free energy changes (delta g(o)'sum) for the synthesis of tryptophan (trp) from chorismic acid via anthranilic acid and indole were calculated, as were those for several possible pathways for the synthesis of iaa from trp, namely via indole-3-acetamide (iam), indole-3-pyruvic acid (ipya), and indole-3-acetonitrile (i ... | 1999 | 10092839 |
| azospirillum irakense produces a novel type of pectate lyase. | the pela gene from the n2-fixing plant-associated bacterium azospirillum irakense, encoding a pectate lyase, was isolated by heterologous expression in escherichia coli. nucleotide sequence analysis of the region containing pela indicated an open reading frame of 1,296 bp, coding for a preprotein of 432 amino acids with a typical amino-terminal signal peptide of 24 amino acids. n-terminal amino acid sequencing confirmed the processing of the protein in e. coli at the signal peptidase cleavage si ... | 1999 | 10198006 |
| sporadic distribution of trna(arg)ccu introns among alpha-purple bacteria: evidence for horizontal transmission and transposition of a group i intron. | a group i intron interrupts the trna(arg)ccu gene of the alpha-purple bacterium agrobacterium tumefaciens (b. reinhold-hurek and d. a. shub, nature [london] 357:173-176, 1992). in this study, we assess the distribution of the corresponding intron among 12 additional species of alpha-purple bacteria. of 10 newly identified trna(arg)ccu genes, we found only two that contained an intron homologous to that of the agrobacterium intron. this restricted and scattered distribution of the trna(arg)ccug i ... | 1999 | 9922276 |
| analysis of nifh gene pool complexity in soil and litter at a douglas fir forest site in the oregon cascade mountain range. | nitrogen-fixing microbial populations in a douglas fir forest on the western slope of the oregon cascade mountain range were analyzed. the complexity of the nifh gene pool (nifh is the marker gene which encodes nitrogenase reductase) was assessed by performing nested pcr with bulk dna extracted from plant litter and soil. the restriction fragment length polymorphisms (rflps) of pcr products obtained from litter were reproducibly different than the rflps of pcr products obtained from the underlyi ... | 1999 | 9925556 |
| auxins upregulate expression of the indole-3-pyruvate decarboxylase gene in azospirillum brasilense. | transcription of the azospirillum brasilense ipdc gene, encoding an indole-3-pyruvate decarboxylase involved in the biosynthesis of indole-3-acetic acid (iaa), is induced by iaa as determined by ipdc-gusa expression studies and northern analysis. besides iaa, exogenously added synthetic auxins such as 1-naphthaleneacetic acid, 2,4-dichlorophenoxypropionic acid, and p-chlorophenoxyacetic acid were also found to upregulate ipdc expression. no upregulation was observed with tryptophan, acetic acid, ... | 1999 | 9973364 |
| site-directed mutagenesis analysis of dratg genes and their downstream region from azospirillum brasilense yu62. | drat and drag genes are involved in posttranslational regulation of nitrogenase activity of azospirillum brasilense yu62. both genes and their downstream region were mutagenized by kmr cassette insertions. analysis of mutations introduced into the dratg region on the a. brasilense yu62 chromosome showed that mutants affected in drat were incapable of regulating nitrogenase activity in response to ammonium. in contrast, a mutant with an insertion in drag was still capable of adp-ribosylating dini ... | 1999 | 10935160 |
| isolation of a psychrotrophic azospirillum sp. and characterization of its extracellular protease. | a novel psychrotrophic bacterium secreting a protease was isolated from a mountain soil in korea. on the basis of a 16s rdna sequence analysis and physiological properties, the isolate was identified as an azospirillum sp. the protease purified from the culture supernatant was a monomer in its native form with an apparent molecular mass of 48.6 kda on sds-page. the protease was active in a broad ph range around 8.5 and at temperatures up to 40 degrees c and stable at temperatures below 30 degree ... | 1999 | 10234836 |
| growth of azospirillum irakense kbc1 on the aryl beta-glucoside salicin requires either sala or salb. | the rhizosphere nitrogen-fixing bacterium azospirillum irakense kbc1 is able to grow on pectin and beta-glucosides such as cellobiose, arbutin, and salicin. two adjacent genes, sala and salb, conferring beta-glucosidase activity to escherichia coli, have been identified in a cosmid library of a. irakense dna. the sala and salb enzymes preferentially hydrolyzed aryl beta-glucosides. a delta(sala-salb) a. irakense mutant was not able to grow on salicin but could still utilize arbutin, cellobiose, ... | 1999 | 10321999 |
| effect of azospirillum brasilense inoculation on urease activity in soil and gamma-sterilized soil. | azospirillum spp. is considered a pgpr (plant growth promoting rhyzobacteria) bacterium, besides this interest, there is little information about its effects on other functional microbial groups or on soil enzymes. in this paper, the impact that a. brasilense 7001 inoculation has on urease activity expression in a typic argiudoll was studied. evolution of urease activity of soil and of gamma-irradiation (25 kgy) sterilized soil, and the inoculated strain survival were tested. the relation betwee ... | 1999 | 10327459 |
| emergence of a laccase-positive variant of azospirillum lipoferum occurs via a two-step phenotypic switching process. | two variants have been isolated from the wild-type azospirillum lipoferum strain 4b. the first variant, 4v(i), spontaneously emerged from the wild-type at frequencies in the order of 10(-4) to 10(-3) per cell generation. compared to the wild-type, the 4v(i) variant gained (production of a carotenoid-like pigment, assimilation of certain carbohydrates) and lost (swimming motility, reduction of triphenyl tetrazolium chloride, acid production from certain sugars) apparently unrelated phenotypic cha ... | 1999 | 10339830 |
| glutamate synthase: a complex iron-sulfur flavoprotein. | glutamate synthase is a complex iron-sulfur flavoprotein that forms l-glutamate from l-glutamine and 2-oxoglutarate. it participates with glutamine synthetase in ammonia assimilation processes. the known structural and biochemical properties of glutamate synthase from azospirillum brasilense, a nitrogen-fixing bacterium, will be discussed in comparison to those of the ferredoxin-dependent enzyme from photosynthetic tissues and of the eukaryotic reduced pyridine nucleotide-dependent form of gluta ... | 1999 | 10357231 |
| characterization of a sugar-binding protein from azospirillum brasilense mediating chemotaxis to and uptake of sugars. | our approach to the isolation of plant-inducible bacterial genes of azospirillum brasilense, based on the analysis of protein patterns of bacteria grown in the presence and in the absence of plant root exudates, led to the identification of an acidic 40 kda protein. cloning and sequencing analysis of the corresponding coding dna region revealed the presence of two open reading frames transcribed in the same orientation. the deduced orf1 protein, which corresponds to the 40 kda protein, is very s ... | 1999 | 10361275 |
| the ipdc promoter auxin-responsive element of azospirillum brasilense, a prokaryotic ancestral form of the plant auxre? | 1999 | 10361293 | |
| involvement of outer-membrane proteins in the aggregation of azospirillum brasilense. | a bioassay was developed to investigate biological factors involved in the aggregation of azospirillum brasilense strain cd. cells were grown for 24 h under aggregation-inducing and non-aggregation-inducing conditions (high and low c:n, respectively) and sonicated for 20 s. the cells were washed by centrifugation and resuspended in potassium phosphate buffer containing the two types of sonication extract. a greater extent of aggregation and higher flocculation were observed after 2-3 h incubatio ... | 1999 | 10376830 |
| interaction of azospirillum lipoferum with wheat germ agglutinin stimulates nitrogen fixation. | in vitro, the nitrogen fixation capability of a. lipoferum is efficiently increased in the presence of wheat germ agglutinin (wga). a putative wga-binding receptor, a 32-kda protein, was detected in the cell capsule. the stimulatory effect required n-acetyl-d-glucosamine dimer (glcnacdi) terminated sugar side chains of the receptor and was dependent on the number of glcnacdi links involved in receptor-wga interface. binding to the primary sugar binding sites on wga had a larger stimulatory effec ... | 1999 | 10383962 |
| a phase variant of azospirillum lipoferum lacks a polar flagellum and constitutively expresses mechanosensing lateral flagella. | flagellation of a nonswimming variant of the mixed flagellated bacterium azospirillum lipoferum 4b was characterized by electron microscopy, and polyclonal antibodies were raised against polar and lateral flagellins. the variant cells lacked a polar flagellum due to a defect in flagellin synthesis and constitutively expressed lateral flagella. the variant cells were able to respond to conditions that restricted the rotation of lateral flagella by producing more lateral flagella, suggesting that ... | 1999 | 10508112 |
| regulation of azospirillum brasilense nifa gene expression by ammonium and oxygen. | the structure and activity of the nifa promoter of azospirillum brasilense was studied using deletion analysis. an essential region for nifa promoter activity was identified between nucleotides -67 and -47 from the identified transcription start site. a sequence resembling a sigma(70) recognition site occurs in this region and may constitute the nifa gene promoter. the regulation of the nifa gene was studied in plasmid and chromosomal nifa::lacz fusions. full expression was obtained under low ox ... | 1999 | 10518727 |
| control of azospirillum brasilense nifa activity by p(ii): effect of replacing tyr residues of the nifa n-terminal domain on nifa activity. | it was previously reported that the n-terminal domain of azospirillum brasilense nifa was a negative regulator of the nifa activity and that the p(ii) protein prevented this inhibition under nitrogen fixing conditions. here, we show that a mutation of a single tyr residue at position 18 of the n-terminal domain of nifa led to an active nifa protein that did not require p(ii) for activation under nitrogen fixation conditions. | 1999 | 10518735 |
| identification, sequencing and structural analysis of a nifa-like gene of acetobacter diazotrophicus. | a recombinant plasmid, pad101, containing a dna fragment of acetobacter diazotrophicus strain pal5 was isolated by its ability to restore nif+ phenotype to a nifa- ntrc- double mutant of azotobacter vinelandii. hybridization with the nifa genes of azospirillum brasilense located the nifa gene more precisely to specific fragments of pad101. dna sequencing of appropriate subclones of pad101 revealed that the nifa gene was adjacent to the nifb gene in a. diazotrophicus, and the 5' end of the nifb g ... | 1999 | 10530336 |
| loss of cytochrome c oxidase activity and acquisition of resistance to quinone analogs in a laccase-positive variant of azospirillum lipoferum. | laccase, a p-diphenol oxidase typical of plants and fungi, has been found recently in a proteobacterium, azospirillum lipoferum. laccase activity was detected in both a natural isolate and an in vitro-obtained phase variant that originated from the laccase-negative wild type. in this study, the electron transport systems of the laccase-positive variant and its parental laccase-negative forms were compared. during exponential (but not stationary) growth under fully aerobic (but not under microaer ... | 1999 | 10542175 |
| surface analysis by x-ray photoelectron spectroscopy in study of bioadhesion and biofilms. | 1999 | 10547806 | |
| degradation of desferrioxamines by azospirillum irakense: assignment of metabolites by hplc/electrospray mass spectrometry. | based on a recent finding that an azospirillum isolate asp-1 possessing high 16s rdna similarity to azospirillum irakense was able to degrade desferrioxamine type siderophores (winkelmann et al. biometals 9, 78-83, 1996), various members of the genus azospirillum were analyzed for their ability to degrade desferrioxamines. while the desferrioxamine-degrading activity was absent or scarcely detectable in strains of a. lipoferum, a. brasilense, a. amazonense, degradation activity seemed to be conf ... | 1999 | 10581690 |
| control of herbaspirillum seropedicae nifa activity by ammonium ions and oxygen. | the activity of a truncated form of herbaspirillum seropedicae nifa in different genetic backgrounds showed that its regulatory domain is involved in nitrogen control but not in o2 sensitivity or fe dependence. the model for nitrogen control involving pii could thus apply to the proteobacteria at large. nifa may have a role in controlling adp-ribosylation of nitrogenase in azospirillum brasilense. | 1999 | 9882688 |
| the ntrb and ntrc genes are involved in the regulation of poly-3-hydroxybutyrate biosynthesis by ammonia in azospirillum brasilense sp7. | azospirillum brasilense sp7 and its ntra (rpon), ntrbc, and ntrc mutants have been evaluated for their capabilities of poly-3-hydroxybutyrate (phb) accumulation in media with high and low ammonia concentrations. it was observed that the ntrbc and ntrc mutants can produce phb in both low- and high-c/n-ratio media, while no significant phb production was observed for the wild type or the ntra mutant in low-c/n-ratio media. further investigation by fermentation analysis indicated that the ntrbc and ... | 2000 | 10618211 |
| characterization of an azospirillum brasilense tn5 mutant with enhanced n(2) fixation: the effect of orf280 on nifh expression. | disruption of an open reading frame (orf) of 840 bp (280 amino acids; orf280) in an azospirillum brasilense tn5 mutant resulted in a pleiotrophic phenotype. besides an enhanced n(2)-fixing capacity and altered expression pattern of a nifh-gusa fusion, growth on the charged polar amino acids glutamate and arginine was severely affected. orf280, similar to previously identified orfs present in bradyrhizobium japonicum (orf277), paracoccus denitrificans (orf278) and rhodobacter capsulatus (orf277), ... | 2000 | 10650197 |
| glutamate synthase: identification of the nadph-binding site by site-directed mutagenesis. | to contribute to the understanding of glutamate synthase and of beta subunit-like proteins, which have been detected by sequence analyses, we identified the nadph-binding site out of the two potential adp-binding regions found in the beta subunit. the substitution of an alanyl residue for g298 of the beta subunit of azospirillum brasilense glutamate synthase (the second glycine in the gxgxxa fingerprint of the postulated nadph-binding site) yielded a protein species in which the flavin environme ... | 2000 | 10651638 |
| n-acyl homoserine lactone binding to the carr receptor determines quorum-sensing specificity in erwinia. | quorum sensing via an n-acyl homoserine lactone (hsl) pheromone controls the biosynthesis of a carbapenem antibiotic in erwinia carotovora. transcription of the carbapenem biosynthetic genes is dependent on the luxr-type activator protein, carr. equilibrium binding of a range of hsl molecules, which are thought to activate carr to bind to its dna target sequence, was examined using fluorescence quenching, dna bandshift analysis, limited proteolysis and reporter gene assays. carr bound the most p ... | 2000 | 10675332 |
| nucleotide and amino-acid sequences of a new-type pectate lyase from an alkaliphilic strain of bacillus. | a pectate lyase (pectate transeliminase; ec 4.2.2.2), designated pel-15e, was purified to homogeneity from a culture broth of alkaliphilic bacillus sp. strain ksm-p15. the purified enzyme had a molecular mass of approximately 33 kda, as determined by sds/page, and a pi of approximately ph 9.2. pel-15e exhibited optimum activity at ph 10.5 and 50-55 degrees c in glycine/naoh buffer. pel-15e had an absolute requirement for ca2+ ions for manifestation of the enzymatic activity and trans-eliminated ... | 2000 | 10691990 |
| increased growth of the microalga chlorella vulgaris when coimmobilized and cocultured in alginate beads with the plant-growth-promoting bacterium azospirillum brasilense. | coimmobilization of the freshwater microalga chlorella vulgaris and the plant-growth-promoting bacterium azospirillum brasilense in small alginate beads resulted in a significantly increased growth of the microalga. dry and fresh weight, total number of cells, size of the microalgal clusters (colonies) within the bead, number of microalgal cells per cluster, and the levels of microalgal pigments significantly increased. light microscopy revealed that both microorganisms colonized the same caviti ... | 2000 | 10742237 |
| functional properties of recombinant azospirillum brasilense glutamate synthase, a complex iron-sulfur flavoprotein. | azospirillum brasilense glutamate synthase is a complex iron-sulfur flavoprotein that catalyses the nadph-dependent reductive transfer of glutamine amide group to the c(2) carbon of 2-oxoglutarate to yield l-glutamate. its catalytically active alphabeta protomer is composed of two dissimilar subunits (alpha subunit, 164.2 kda; beta subunit, 52.3 kda) and contains one fad (at site 1, the pyridine nucleotide site within the beta subunit), one fmn (at site 2, the 2-oxoglutarate/l-glutamate site in ... | 2000 | 10785395 |
| mutants with enhanced nitrogenase activity in hydroponic azospirillum brasilense-wheat associations. | the effect of a mutation affecting flocculation, differentiation into cyst-like forms, and root colonization on nitrogenase expression by azospirillum brasilense is described. the gene flca of strain sp7 restored these phenotypes in spontaneous mutants of both strains sp7 and sp245. employing both constitutive pla-lacz and nifh-lacz reporter fusions expressed in situ, the colony morphology, colonization pattern, and potential for nitrogenase activity of spontaneous mutants and flca tn5-induced m ... | 2000 | 10788397 |
| [initial stages of interaction of azospirillum brasilense bacteria with wheat germ roots: adsorption, deformation of root hairs]. | the initial stages of colonization of wheat roots by cells of azospirillum brasilense strains 75 and 80 isolated from soils of the saratov oblast were studied. the adsorption of azospirilla on root hairs of soft spring wheats rapidly increased in the first hours of incubation, going then to a plateau phase. within the first 15 h of incubation, exponential-phase cells were adsorbed more intensively than stationary-phase cells. conversely, stationary-phase cells were adsorbed more intensively than ... | 2000 | 10808499 |
| genome structure of the genus azospirillum. | azospirillum species are plant-associated diazotrophs of the alpha subclass of proteobacteria. the genomes of five of the six azospirillum species were analyzed by pulsed-field gel electrophoresis. all strains possessed several megareplicons, some probably linear, and 16s ribosomal dna hybridization indicated multiple chromosomes in genomes ranging in size from 4.8 to 9.7 mbp. the nifhdk operon was identified in the largest replicon. | 2000 | 10869094 |
| indole-3-acetic acid: a reciprocal signalling molecule in bacteria-plant interactions. | 2000 | 10878760 | |
| surface characteristics of azospirillum brasilense in relation to cell aggregation and attachment to plant roots. | the free-living bacteria of the genus azospirillum live in close association with plant roots and represent one of the best-characterized plant growth promoting rhizobacteria (pgpr). the attachment of azospirillum to the roots is essential for the establishment of an efficient association with the host plant. azospirillum cells are able to aggregate under certain environmental conditions, leading to the formation of bacterial flocs. the bacterial surface plays an important role in the establishm ... | 2000 | 10890352 |
| isolation and sequence analysis of repa from the incurable 90 mda plasmid of azospirillum brasilense. | an open reading frame encoding a protein of 312 amino acids was identified in an essential region of the 90 mda plasmid of azospirillum brasilense. the putative protein shows similarity with repa proteins of plasmids of sphingomonas aromacitovorans, rhodotermus marinus, chlorobium limicola and bifidobacterium asteroides and with the repa protein of the broad host range plasmid psa. a putative helix-turn-helix motif was identified in the central part of the a. brasilense repa protein. analysis of ... | 2000 | 10902916 |
| unlabeled helper oligonucleotides increase the in situ accessibility to 16s rrna of fluorescently labeled oligonucleotide probes. | target site inaccessibility represents a significant problem for fluorescence in situ hybridization (fish) of 16s rrna with oligonucleotide probes. here, unlabeled oligonucleotides (helpers) that bind adjacent to the probe target site were evaluated for their potential to increase weak probe hybridization signals in escherichia coli dsm 30083(t). the use of helpers enhanced the fluorescence signal of all six probes examined at least fourfold. in one case, the signal of probe eco474 was increased ... | 2000 | 10919826 |
| starvation-induced changes in the cell surface of azospirillum lipoferum. | three starvation regimes (a deficient culture medium, a saline buffer solution and distilled water) were evaluated for their possible effect on cell surface characteristics of azospirillum lipoferum 1842 related to the initial adsorption of the bacterium to surfaces. the bacteria survived for 7 days in all media although they did not multiply. upon transfer from a rich growth medium (nutrient agar) to starvation conditions, cell surface hydrophobicity dropped sharply but recovered its initial va ... | 2000 | 10922497 |
| extracellular polysaccharide composition of azospirillum brasilense and its relation with cell aggregation. | the exopolysaccharide (eps) and capsular polysaccharide (cps) composition of four azospirillum brasilense strains differing in their aggregation capacity was analyzed by high performance anion exchange chromatography. when growing the different strains in an aggregation inducing medium containing a high carbon:nitrogen (c:n) ratio, both eps and cps showed a positive correlation between aggregation and the relative amount of arabinose. arabinose was not detected in polysaccharides from sp72002, a ... | 2000 | 10930748 |
| effect of associative bacteria on element composition of barley seedlings grown in solution culture at toxic cadmium concentrations. | the response of barley seedlings to inoculation with associative rhizobacteria azospirillum lipoferum 137, arthrobacter mysorens 7, agrobacterium radiobacter 10 and flavobacterium sp. l30 was studied in hydroponic and quartz sand cultures in the presence of 50 microm cdcl2. cadmium caused severe inhibition in the growth and uptake of nutrient elements by the plants. inoculation with the bacteria slightly stimulated root length and biomass of hydroponically grown cd-treated seedlings. the bacteri ... | 2000 | 10950194 |
| the salcab operon of azospirillum irakense, required for growth on salicin, is repressed by salr, a transcriptional regulator that belongs to the lacl/galr family. | the salab genes of azospirillum irakense kbc1, which encode two aryl-beta-glucosidases, are required for growth on salicin. in the 4-kb region upstream of the salab genes, two additional genes, salc and salr, were identified. salc shows characteristics of the outer membrane receptors in the fepa/fhua family. the salc ab genes are transcribed as a polycistronic mrna. the salr gene encodes a protein homologous to the laci/galr family of transcriptional repressors. expression of the sal operon, mea ... | 2000 | 10954090 |
| a broad-host-range plasmid for isolating mobile genetic elements in gram-negative bacteria. | plasmid pgbg1 was constructed to isolate mobile genetic elements in a wide variety of gram-negative bacteria. the mutation target, carried on a broad-host-range vector, allows positive selection for tetracycline resistance. in tests using several gram-negative bacteria we could detect transposition events of either insertion sequences or transposons. a new insertion sequence (is) element was identified in ralstonia eutropha. | 2000 | 10964631 |
| azospirillum, a free-living nitrogen-fixing bacterium closely associated with grasses: genetic, biochemical and ecological aspects. | azospirillum represents the best characterized genus of plant growth-promoting rhizobacteria. other free-living diazotrophs repeatedly detected in association with plant roots, include acetobacter diazotrophicus, herbaspirillum seropedicae, azoarcus spp. and azotobacter. four aspects of the azospirillum-plant root interaction are highlighted: natural habitat, plant root interaction, nitrogen fixation and biosynthesis of plant growth hormones. each of these aspects is dealt with in a comparative ... | 2000 | 10978548 |
| energy taxis is the dominant behavior in azospirillum brasilense. | energy taxis encompasses aerotaxis, phototaxis, redox taxis, taxis to alternative electron acceptors, and chemotaxis to oxidizable substrates. the signal for this type of behavior is originated within the electron transport system. energy taxis was demonstrated, as a part of an overall behavior, in several microbial species, but it did not appear as the dominant determinant in any of them. in this study, we show that most behavioral responses proceed through this mechanism in the alpha-proteobac ... | 2000 | 11029423 |
| effect of water-soluble vitamins on the production of indole-3-acetic acid by azospirillum brasilense. | the effects of six water-soluble vitamins on tryptophan-dependent synthesis of indole-3-acetic acid in azospirillum brasilense were investigated. a multifactorial regression analysis was employed to produce models of indole-3-acetic acid synthesis versus concentrations of tryptophan and the vitamins added to the growth medium. very low levels of the b-group vitamins added at 10 to 100 microg l(-1) affected production of indole-3-acetic acid in a. brasilense. the largest release of this phytohorm ... | 2000 | 11061189 |
| identification and characterization of the omaa gene encoding the major outer membrane protein of azospirillum brasilense. | the major outer membrane protein (momp) of azospirillum brasilense was purified and degenerate oligonucleotides were constructed on the basis of partial internal amino acid sequences. pcr products were obtained using total dna of a. brasilense as template. one of these, a 766-bp fragment, was dig-labelled and used in southern hybridization against a. brasilense dna and a genomic library of a. brasilense in escherichia coli. a clone containing a 20-kb ecori insert in plafr3 was identified by pcr ... | 2000 | 11092733 |
| isolation and sequence analysis of the trpba gene cluster, encoding tryptophan synthase, from azospirillum brasilense. | the trpba gene cluster of azospirillum brasilense sp7 was isolated by complementation of an escherichia coli trpba mutant. both genes code for the two subunits of tryptophan synthase, which catalyzes the last step in tryptophan biosynthesis. no structural features indicating transcriptional regulation could be identified. upstream of the trpba cluster an open reading frame encoding a putative periplasmic binding protein, involved in amino acid transport, was identified. analysis of the downstrea ... | 2000 | 11092742 |
| characterization of a major cluster of nif, fix, and associated genes in a sugarcane endophyte, acetobacter diazotrophicus. | a major 30.5-kb cluster of nif and associated genes of acetobacter diazotrophicus (syn. gluconacetobacter diazotrophicus), a nitrogen-fixing endophyte of sugarcane, was sequenced and analyzed. this cluster represents the largest assembly of contiguous nif-fix and associated genes so far characterized in any diazotrophic bacterial species. northern blots and promoter sequence analysis indicated that the genes are organized into eight transcriptional units. the overall arrangement of genes is most ... | 2000 | 11092875 |
| physiological evidence for differently regulated tryptophan-dependent pathways for indole-3-acetic acid synthesis in azospirillum brasilense. | disruption of ipdc, a gene involved in indole-3-acetic acid (iaa) production by the indole pyruvate pathway in azospirillum brasilense sp7, resulted in a mutant strain that was not impaired in iaa production with lactate or pyruvate as the carbon source. a tryptophan auxotroph that is unable to convert indole to tryptophan produced iaa if tryptophan was present but did not synthesise iaa from indole. similar results were obtained for a mutant strain with additional mutations in the genes ipdc an ... | 2000 | 11129057 |
| preferential occurrence of diazotrophic endophytes, azoarcus spp., in wild rice species and land races of oryza sativa in comparison with modern races. | several diazotrophic species of azoarcus spp. occur as endophytes in the pioneer plant kallar grass. the purpose of this study was to screen asian wild rice and cultivated oryza sativa varieties for natural association with these endophytes. populations of culturable diazotrophs in surface-sterilized roots were characterized by 16s rdna sequence analysis, and azoarcus species were identified by genomic fingerprints. a. indigens and azoarcus sp. group c were detected only rarely, whereas azoarcus ... | 2000 | 11220300 |
| enhancement of polygalacturonase activity during auxin induced para nodulation and endorhizosphere colonization of azospirillum in rice roots. | effect of different auxins, namely, 2,4-dichlorophenoxyacetic acid (2,4-d), naphthalene acetic acid (naa) and indole acetic acid (iaa) and azospirillum brasilense bioinoculation on the enhancement of polygalacturonase (pg) activity in rice roots during para nodulation and endorhizosphere colonization of azospirillum was studied under in vitro condition. it was observed that azospirillum bioinoculation could augment pg activity of rice roots to a lesser extent without any root morphogenesis where ... | 2000 | 11233091 |
| [azospirillum amazonense: its presence in the sugar cane area of the province of tucumán]. | we confirm the presence of azospirillum amazonense in the sugar cane area of the province of tucumán. several strains were isolated from sugar-cane roots in different places. phenotypic and genotypic characteristics coincided with those described for this species. this new one is being added to the other two species, a. brasilense and a. lipoferum, already reported. | 2000 | 11149152 |
| [transposon tnphoa mutagenesis as a method of obtaining mutants of azospirillum brasilense by motility and flagellation]. | three a. brasilense strains (s27, spbr14, and kr77) did not hydrolyze the chromogenic substrate of alkaline phosphatase (phoa), x-phosphate, in situ, and were used as recipients in experiments on tnphoa mutagenesis. kmr transconjugates were obtained only for a. brasilense s27, 85% of them were also phoa+. about 12% tnphoa mutants of a. brasilense s27 had reduces capacity to swarming and 3% of mutants neither swam nor swarmed. these totally immotile clones were examined under transmission electro ... | 2000 | 11186453 |
| cross-talk and ammonia channeling between active centers in the unexpected domain arrangement of glutamate synthase. | the complex iron-sulfur flavoprotein glutamate synthase catalyses the reductive synthesis of l-glutamate from 2-oxoglutarate and l-glutamine, a reaction in the plant and bacterial pathway for ammonia assimilation. the enzyme functions through three distinct active centers carrying out l-glutamine hydrolysis, conversion of 2-oxoglutarate into l-glutamate, and electron uptake from an electron donor. | 2000 | 11188694 |
| structure and colonization dynamics of epiphytic bacterial communities and of selected component strains on tomato (lycopersicon esculentum) leaves. | the sizes and compositions of bacterial populations found on leaves of greenhouse and field grown tomato plants were studied by dilution plating, fatty acid methyl ester analysis (fame), and biolog plates of isolates in pure cultures. in the greenhouse, overhead-irrigated plants sustained higher microbial populations (up to 105 cfu g-1) than soil-irrigated plants (103 cfu g-1). strains isolated from overhead-irrigated plants grown in a vegetable garden (n = 216) and from greenhouse-grown plants ... | 2000 | 12035088 |
| selection and evaluation of azospirillum brasilense strains growing at a sub-optimum temperature in rhizocoenosis with wheat. | fourteen azospirillum brasilense strains growing at a sub-optimum temperature were selected based on their ability to grow and carry out plant growth promoting activities at 22 degrees c. the strains were tested for their response to inoculation in wheat (two popular cultivars, hd2285 and wh547, under sterile conditions) crop using sterile and nonsterile rooting medium. significant increase in plant growth parameters was observed; the overall response to inoculation was better in cultivar hd2285 ... | 2001 | 11830945 |
| [the role of cell surface bacterial lectins in the aggregation of azospirilla]. | the mutant strain azospirillum brasilense sp7.2.3 with impaired lectin activity exhibited poorer cell aggregation than its parent strain a. brasilense sp7(s) both in the exponential and stationary growth phases. the pretreatment of bacterial cells with the specific haptens (l-fucose and d-galactose) of a lectin located at the cell surface of the mutant strain was found to inhibit the aggregation of azospirilla. the specific binding of the a. brasilense sp7(s) lectin to the extracellular polysacc ... | 2001 | 11558272 |
| [study of protective role of the polysaccharide-containing components of capsules of azospirillum brasilense]. | the involvement of the carbohydrate components of the azospirillum brasilense sp245 capsules in bacterial protection from the action of extreme factors was investigated. the survival of encapsulated and non-encapsulated azospirilla exposed to elevated (46-48 degrees c) and below-freezing (-20 and -70 degrees c) temperatures, extreme ph values (2 and 10), and to drying was studied. high-molecular-weight carbohydrate-containing complexes (lipopolysaccharide-protein complex and polysaccharide-lipid ... | 2001 | 11558276 |
| recent developments in the structural organization and regulation of nitrogen fixation genes in herbaspirillum seropedicae. | herbaspirillum seropedicae is a nitrogen-fixing bacterium found in association with economically important gramineae. regulation of nitrogen fixation involves the transcriptional activator nifa protein. the regulation of nifa protein and its truncated mutant proteins is described and compared with that of other nitrogen fixation bacteria. nitrogen fixation control in h. seropedicae, of the beta-subgroup of proteobacteria, has regulatory features in common with klebsiella pneumoniae, of the gamma ... | 2001 | 11566390 |
| improvement in bioavailability of tricalcium phosphate to cymbopogon martinii var. motia by rhizobacteria, amf and azospirillum inoculation. | the interactive effects of phosphate solubilizing bacteria, n2 fixing bacteria and arbuscular mycorrhizal fungi (amf) were studied in a low phosphate alkaline soil amended with tricalcium insoluble source of inorganic phosphate on the growth of an aromatic grass palmarosa (cymbopogon martinii). the microbial inocula consisted of the am fungus glomus aggregatum, phosphate solubilizing rhizobacteria bacillus polymyxa and n2 fixing bacteria azospirillum brasilense. these rhizobacteria behaved as "m ... | 2001 | 11572454 |
| sequencing and promoter analysis of the nifenxorf3orf5fdxanifq operon from azospirillum brasilense sp7. | a 40-kb dna region containing the major cluster of nif genes has been isolated from the azospirillum brasilense sp7 genome. in this region three nif operons have been identified: nifhdkorf1y, nifenxorf3orf5fdxanifq and orf2nifusvorf4. the operons containing nifenx and nifusv genes are separated from the structural nifhdkorf1y operon by about 5 kb and 10 kb, respectively. the present study shows the sequence analysis of the 6045-bp dna region containing the nifenx genes. the deduced amino acid se ... | 2001 | 11668346 |
| control of nitrogenase reactivation by the glnz protein in azospirillum brasilense. | the glnz mutant of azospirillum brasilense (strain 7611) showed only partial recovery (20 to 40%) after 80 min of ammonia-induced nitrogenase switch-off, whereas the wild type recovered totally within 10 min. in contrast, the two strains showed identical anoxic-induced switch-on/switch-off, indicating no cross talk between the two reactivation mechanisms. | 2001 | 11673445 |
| endophytic colonization and in planta nitrogen fixation by a herbaspirillum sp. isolated from wild rice species. | nitrogen-fixing bacteria were isolated from the stems of wild and cultivated rice on a modified rennie medium. based on 16s ribosomal dna (rdna) sequences, the diazotrophic isolates were phylogenetically close to four genera: herbaspirillum, ideonella, enterobacter, and azospirillum. phenotypic properties and signature sequences of 16s rdna indicated that three isolates (b65, b501, and b512) belong to the herbaspirillum genus. to examine whether herbaspirillum sp. strain b501 isolated from wild ... | 2001 | 11679357 |
| recovery and phylogenetic analysis of nifh sequences from diazotrophic bacteria associated with dead aboveground biomass of spartina alterniflora. | dna was extracted from dry standing dead spartina alterniflora stalks as well as dry spartina wrack from the north inlet (south carolina) and sapelo island (georgia) salt marshes. partial nifh sequences were pcr amplified, the products were separated by denaturing gradient gel electrophoresis (dgge), and the prominent dgge bands were sequenced. most sequences (109 of 121) clustered with those from alpha-proteobacteria, and 4 were very similar (>99%) to that of azospirillum brasilense. seven sequ ... | 2001 | 11679360 |
| [cloning and functional analysis of glnb from azospirillum brasilense yu62]. | the glnb gene of a. brasilense yu62 was determined in a 3.7 kb ecori + psti fragment. the glna is located downstream of glnb and an orf for hypothetical protein is on upstream of glnb. the deduced amino acid sequence of pii encoded by glnb is 71%, 77%, 79% and 69% identical to that of k. pneumoniae, bradyrhizobium japonicum, rhizobium leguninosarum and e. coli, respectively. a km-casette was inserted into bglii site of glnb coding region and glnb- mutant was obtained by homologous recombination. ... | 2001 | 11695269 |
| effect of some granular insecticides currently used for the treatment of maize crops (zea mays) on the survival of inoculated azospirillum lipoferum. | four insecticides, carbofuran, chlormephos, terbufos and benfuracarb, currently used on maize (zea mays) at sowing, were tested for their compatibility with azospirillum lipoferum strain crt1 used as an inoculant to improve maize growth and yield. the growth or survival of a lipoferum was studied in the presence of the insecticides: (1) in liquid and solid cultures of the bacteria, (2) when a commercial inoculant (azogreen-m, liphatech, meyzieu, france) was inoculated directly on insecticide gra ... | 2001 | 11721526 |
| structural effects of the azospirillum lipopolysaccharides in cell suspensions. | the structural influence of azospirillum lipopolysaccharides (lps) and lipopolysaccharide-protein complexes (lppc) on carrot, erythrocyte, and bacterial cell suspensions was explored. the structural potentialities of o-specific polysaccharide fragments of lps and protein fractions of lppc were also evaluated. an ability to induce the formation of three kinds of structures in the cell suspensions was revealed depending on the chemical composition of the preparations used. the first and the second ... | 2001 | 11749198 |
| [relationship between lectin, alpha-, beta-glucosidase, and beta-galactosidase activities of azospirillum]. | the activities of alpha-glucosidase, beta-glucosidase, and beta-galactosidase were studied during the isolation and purification of lectins from azospirillum brasilense sp7 and azospirillum lipoferum 59b cells. these enzymatic activities were revealed in crude extracts of surface proteins, protein fraction precipitated with ammonium sulfate or ethanol-acetone mixture, and protein fraction obtained by gel filtration on sephadex g-75. the distribution of the enzymes between different protein fract ... | 2001 | 11763784 |
| [formation of polar bundles of pili on a cell and the behavior of azospirillum brasilense in semiliquid agar]. | this paper describes the formation of single polar bundles of pili on azospirillum brasilense cells, the twitching motility of cell aggregates, and a new type of social behavior--the dispersal of bacterial cells in semiliquid agar associated with the formation of granular inclusions (the so-called gri+ phenotype)--which is an alternative to swarming (the swa+ phenotype). the wild-type a. brasilense cells occurring in a semiliquid agar may show either the swa+gri-, or swa-gri-, or swa-gri+ phenot ... | 2001 | 11763787 |
| azospirillum doebereinerae sp. nov., a nitrogen-fixing bacterium associated with the c4-grass miscanthus. | a new group of nitrogen-fixing azospirillum sp. bacteria was isolated from the roots of the c4-gramineous plant miscanthus. polyphasic taxonomy was performed, including auxanography using api galleries, physiological tests and 16s rrna sequence comparison. the ability of the isolates to fix dinitrogen was evaluated by amplification of the nifd gene, immunodetection of the dinitrogenase reductase and acetylene-reduction assay. on the basis of these results, the nitrogen-fixing isolates represent ... | 2001 | 11211255 |
| nitrogen fixation genes in an endosymbiotic burkholderia strain. | in this paper we report the identification and characterization of a dna region containing putative nif genes and belonging to a burkholderia endosymbiont of the arbuscular mycorrhizal fungus gigaspora margarita. a genomic library of total dna extracted from the fungal spores was also representative of the bacterial genome and was used to investigate the prokaryotic genome. screening of the library with azospirillum brasilense nifhdk genes as the prokaryotic probes led to the identification of a ... | 2001 | 11157237 |
| [the different functions of glnb and glnz from azospirillum brasilense yu62 in the control of nitrogen fixation]. | the glnb and glnz genes of a. brasilense have 70% homology at nucleotide sequence. glnb is located in a 3.7 kb eco ri+ psti fragment and glnz is located in a 3.7 kb sali fragment. both glnb and glnz genes were mutagenized by kmr cassette insertions and glnb- and glnz- mutants were obtained. glnb- mutant did not have any nitrogenase activity, while glnz- mutant still has nitrogenase activity. the coding regions of glnb and glnz were cloned into pvk100 vectors and recombinant plasmids pvk-ii and p ... | 2001 | 12552797 |
| [cloning sequencing and expression pattern, functional analysis of nifa gene in azospirillum brasilense yu62]. | the nifa gene of azospirillum brasilense yu62 was cloned and sequenced. the expression of nifa gene was investigated in wild type strain azospirillum brasilense yu62. the results show that expression of nifa gene is not repressed by ammounium and oxygen completely. but the expression of yu62 nifa gene is different from that of strain sp7 nifa gene. expression of yu62 nifa seems more sensitive to oxygen than that of sp7 nifa which shows the highest expression in condition of aerobic, while the yu ... | 2001 | 12552819 |
| ultrastructure of interaction in alginate beads between the microalga chlorella vulgaris with its natural associative bacterium phyllobacterium myrsinacearum and with the plant growth-promoting bacterium azospirillum brasilense. | chlorella vulgaris, a microalga often used in wastewater treatment, was coimmobilized and coincubated either with the plant growth-promoting bacterium azospirillum brasilense, or with its natural associative bacterium phyllobacterium myrsinacearum, in alginate beads designed for advanced wastewater treatment. interactions between the microalga and each of the bacterial species were followed using transmission electron microscopy for 10 days. initially, most of the small cavities within the beads ... | 2001 | 15049443 |
| [effect of integrating the pjff350 vector into the 85-mda plasmid of azospirillum brasilense sp245 on bacterial flagellation and mobility]. | results of genetic analysis of three derivatives of azospirillum brasilense sp245 (strains bk570, sk051, and sk248) carrying cointegrates of plasmids 85-mda and pjff350 (the vector for omegon mutagenesis), which manifest abnormalities in flagellation and motility, are presented. it was shown for the first time that the integration of the suicide vector into one of azospirillum resident plasmids is accompanied by the formation of various fusion products and changes in flagellation and motility of ... | 2001 | 11253424 |
| [complementation analysis of mutants of the associative bacteria azospirillum brasilense sp245 and s27, defective in mobility and flagellation]. | three mutants of azospirillum brasilense sp245 incapable of both formation of the polar flagellum (fla-phenotype) and swarming in semisolid media (swa-phenotype) were characterized. these mutants were shown to have lost the 85-mda plasmid and to carry the tn5-mob transposon and psup5011 vector in different regions of their genomes. with the use of a. brasilense sp245 gene bank, the capacity for both polar flagellum formation and swarming was restored in the above mutants and in the previously ge ... | 2001 | 11253425 |
| pectate lyase 10a from pseudomonas cellulosa is a modular enzyme containing a family 2a carbohydrate-binding module. | pectate lyase 10a (pel10a) enzyme from pseudomonas cellulosa is composed of 649 residues and has a molecular mass of 68.5 kda. sequence analysis revealed that pel10a contained a signal peptide and two serine-rich linker sequences that separate three modules. sequence similarity was seen between the 9.2 kda n-terminal module of pel10a and family 2a carbohydrate-binding modules (cbms). this n-terminal module of pel10a was shown to encode an independently functional module with affinity to crystall ... | 2001 | 11256960 |
| isolation and 16s rrna sequence analysis of the beneficial bacteria from the rhizosphere of rice. | the present study deals with the isolation of plant growth promoting rhizobacteria (pgpr) from rice (variety niab irri-9) and the beneficial effects of these inoculants on two basmati rice varieties. nitrogen-fixing activity (acetylene-reduction activity) was detected in the roots and submerged shoots of field-grown rice variety niab irri-9. estimation of the population size of diazotrophic bacteria by ara-based mpn (acetylene reduction assay-based most probable number) in roots and shoots indic ... | 2001 | 11261489 |
| stable rk2-derived cloning vectors for the analysis of gene expression and gene function in gram-negative bacteria. | the construction of several stable rk2-derived cloning vectors for the analysis of gene expression and function in gram-negative bacteria is reported. plasmid stability is conferred by the rk2 par locus or by insertion of the spsab or spscd symbiotic plasmid stability loci from pngr234a of rhizobium sp. ngr234. the vectors carry multiple cloning sites with protection against read-through transcriptional activity of vector sequences. vector derivatives with the constitutive nptii promoter or a pr ... | 2001 | 11277442 |
| bacterial diversity and community structure in an aerated lagoon revealed by ribosomal intergenic spacer analyses and 16s ribosomal dna sequencing. | we investigated the bacterial community structure in an aerated plug-flow lagoon treating pulp and paper mill effluent. for this investigation, we developed a composite method based on analyses of pcr amplicons containing the ribosomal intergenic spacer (ris) and its flanking partial 16s rrna gene. community percent similarity was determined on the basis of ris length polymorphism. a community succession was evident in the lagoon, indicated by a progressive community transition through seven sam ... | 2001 | 11282606 |
| azospirillum brasilense and azospirillum lipoferum hydrolyze conjugates of ga20 and metabolize the resultant aglycones to ga1 in seedlings of rice dwarf mutants. | azospirillum species are plant growth-promotive bacteria whose beneficial effects have been postulated to be partially due to production of phytohormones, including gibberellins (gas). in this work, azospirillum brasilense strain cd and azospirillum lipoferum strain usa 5b promoted sheath elongation growth of two single gene ga-deficient dwarf rice (oryza sativa) mutants, dy and dx, when the inoculated seedlings were supplied with [17,17-2h2]ga20-glucosyl ester or [17,17- 2h2]ga20-glucosyl ether ... | 2001 | 11299384 |
| purification of the major outer membrane protein of azospirillum brasilense, its affinity to plant roots, and its involvement in cell aggregation. | the major outer membrane protein (momp) of the nitrogen-fixing rhizobacterium azospirillum brasilense strain cd was purified and isolated by gel filtration, and antiserum against this protein was obtained. a screening of the binding of outer membrane proteins (omps) of a. brasilense to membrane-immobilized root extracts of various plant species revealed different affinities for the momp, with a stronger adhesion to extracts of cereals in comparison with legumes and tomatoes. moreover, this prote ... | 2001 | 11310743 |
| the cela gene, encoding a glycosyl hydrolase family 3 beta-glucosidase in azospirillum irakense, is required for optimal growth on cellobiosides. | the cela beta-glucosidase of azospirillum irakense, belonging to glycosyl hydrolase family 3 (ghf3), preferentially hydrolyzes cellobiose and releases glucose units from the c(3), c(4), and c(5) oligosaccharides. the growth of a deltacela mutant on these cellobiosides was affected. in a. irakense, the ghf3 beta-glucosidases appear to be functional alternatives for the ghf1 beta-glucosidases in the assimilation of beta-glucosides by other bacteria. | 2001 | 11319128 |
| determination of the midpoint potential of the fad and fmn flavin cofactors and of the 3fe-4s cluster of glutamate synthase. | glutamate synthase is a complex iron-sulfur flavoprotein that catalyzes the reductive transfer of the l-glutamine amide group to c(2) of 2-oxoglutarate, forming two molecules of l-glutamate. the bacterial enzyme is an alphabeta protomer, which contains one fad (on the beta subunit, approximately 50 kda), one fmn (on the alpha subunit, approximately 150 kda), and three different fe-s clusters (one 3fe-4s center on the alpha subunit and two 4fe-4s clusters at an unknown location). to address the p ... | 2001 | 11331018 |
| [the role of polysaccharide-containing components of the azospirillum brasilense capsule in adsorbing bacteria on wheat seedling roots]. | azospirillum brasilense cells deprived of capsular exopolysaccharides completely lost their ability to bind wheat germ agglutinin (wga) and much of their ability to attach to wheat seedling roots. the decapsulation of bacterial cells by washing them with a nacl solution led to an increase in the relative hydrophobicity of the cell surface. the pretreatment of wheat seedling roots with n-acetyl-d-glucosamine (glcnac) or the glcnac-containing polysaccharide complexes stripped from azospirillum cel ... | 2001 | 11338835 |
| [electrooptical properties of soil nitrogen-fixing bacterium azospirillum brasilense: effect of copper ions]. | the effects of copper ions on the uptake of some essential metals in the biomass and the electrooptical properties of cell suspensions of the nitrogen-fixing soil bacterium azospirillum brasilense sp. 245 were studied. copper cations were shown to be effectively taken up by the cell biomass from the culture medium. the addition of copper ions increased the rate of uptake of some other metals present in the culture medium. this was accompanied by changes in the electrooptical characteristics of c ... | 2001 | 11357434 |
| an evolutionary alternative system for aryl beta-glucosides assimilation in bacteria. | some bacteria of the soil microflora or of the digestive systems of mammals can grow on aryl beta-glucosides as sole carbon sources. the bgl operon of e. coli is the paradigm for such a catabolic pathway. in azospirillum irakense, the two adjacent genes salab encode beta-glucosidases which are required for salicin assimilation. in this report, we analyse the sequence of salc, the last gene to be identified in the salcab operon and investigate the phylogenetic origins of the sal and bgl genes. th ... | 2001 | 11361080 |
| influence of divalent cations on the catalytic properties and secondary structure of unadenylylated glutamine synthetase from azospirillum brasilense. | fully unadenylylated glutamine synthetase (gs) from the endophytic bacterium azospirillum brasilense sp245 was isolated and purified. the enzyme was electrophoretically homogeneous and contained strongly bound metal ions, which could not be removed by dialysis. mn2+, mg2+, and co2+ were found to be effective in supporting biosynthetic activity of the a. brasilense gs. some kinetic properties of mn2+-activated and mg2+-activated unadenylylated gs were characterized. circular dichroism analysis of ... | 2001 | 11368271 |
| transformation studies of bacillus thuringiensis cryic gene into a nitrogen-fixing azospirillum lipoferum. | a lepidopteran toxin gene, cryic (psb607) from entomopathogenic bacillus thuringiensis subsp. aizawai was introduced into nitrogen-fixing azospirillum lipoferum by transformation. regeneration of spheroplasts was achieved at 99% with 39% frequency of regeneration. transformants were screened on nb kanamycin with ampicillin plates and 4 transformants were selected after ten generations. sds-page and western blot analysis confirmed the presence of a 68 kda protein in the transformants. studies on ... | 2001 | 11371015 |
| expression of the acc deaminase gene fromenterobacter cloacae uw4 in azospirillum brasilense. | the acc deaminase structural gene (acds) from enterobacter cloacae uw4 was cloned in the broad host range plasmid prk415 under the control of the lac promoter and transferred into azospirillum brasilense cd and sp245. a. brasilensecd and sp245 transformants showed high acc deaminase activity, similar to that observed in enterobacter cloacae uw4. the expression of acc deaminase improved the existing growth promoting activity of azospirillum. the roots of tomato and canola seedlings were significa ... | 2001 | 11391466 |
| effects of rhizobacteria and root symbionts on the reproduction of meloidogyne javanica and growth of chickpea. | the effects of rhizobacteria, i.e. pseudomonas fluorescens, azotobacter chyroococcum and azospirillum brasilense, alone and in combination with root symbionts, rhizobium sp. and glomus mosseae, on the growth of chickpea, cicer arietinum, and reproduction of meloidogyne jaranica were studied. when added alone g. mosseae was better at improving plant growth and reducing galling and nematode reproduction than any other tested organism. application of p. fluorescens caused an almost similar increase ... | 2001 | 11396906 |
| design and application of new 16s rrna-targeted oligonucleotide probes for the azospirillum-skermanella-rhodocista-cluster. | the genera azospirillum, skermanella and rhodocista form a phylogenetic subgroup within the alfa subclass of proteobacteria. based on comparative 16s rrna sequence analysis a nested set of new oligonucleotide probes was designed. it comprises probes for the whole genus cluster azospirillum-skermanella-rhodocista, for the azospirilli subcluster i including a. lipoferum, a. doebereinerae, a. largimobile, a. brasilense and a. halopraeferens, for the azospirilli subcluster ii including a. amazonense ... | 2001 | 11403403 |
| identification and characterization of a periplasmic nitrate reductase in azospirillum brasilense sp245. | the azospirillum brasilense sp245 napabc genes, encoding nitrate reductase activity, were isolated and sequenced. the derived protein sequences are very similar throughout the whole nap segment to the napabc protein sequences of escherichia coli, pseudomonas sp. g-179, ralstonia eutropha, rhodobacter sphaeroides, and paracoccus denitrificans. based on whole-cell nitrate reductase assays with the artificial electron donors benzyl viologen and methyl viologen, and assays with periplasmic cell-free ... | 2001 | 11409544 |