Publications
| Title | Abstract | Year(sorted ascending) Filter | PMID Filter |
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| molecular cloning and sequence analysis of an azospirillum brasilense indole-3-pyruvate decarboxylase gene. | azospirillum brasilense isolated from the rhizosphere of different plants has the ability to excrete indole-3-acetic acid (iaa) into the culture media. cosmid p0.2, isolated from an a. brasilense sp245 genome library in plafr1, complements the tn5-induced mutant spm7918 of a. brasilense sp6 which excretes reduced amounts of iaa. restriction mapping and gene expression studies identified a bglii-ecori 4.3 kb fragment of p0.2 sufficient for the restoration of high levels of iaa production in mutan ... | 1994 | 8202090 |
| control of nifh transcription in azospirillum brasilense: involvement of nifa and of cis-acting sequences. | the regulatory sequences of azospirillum brasilense sp7 nifh gene were fused with the cam reporter gene and used for studying the factors controlling nifh transcription. a dna sequence, downstream the atg codon of nifh, that could be involved in the negative regulation of nifh transcription, was identified. the effect of 1 and 2 mm of ammonium on the transcription of the a. brasilense nifh gene and on the nitrogenase activity, in the presence of the klebsiella pneumoniae nifa protein, was examin ... | 1994 | 8125248 |
| the ph-dependent behavior of catalytic activities of azospirillum brasilense glutamate synthase and iodoacetamide modification of the enzyme provide evidence for a catalytic cys-his ion pair. | the ph dependence of the kinetic parameters of the glutamine- and ammonia-dependent reactions of azospirillum brasilense glutamate synthase revealed the presence of ionizable groups with pka values between 6 and 10 involved in the binding of the substrates and in catalytic steps. the v profile of the glutamine-dependent reaction is complicated by a deviation from a simple bell-shaped curve between ph 8 and ph 10, which may suggest that deprotonation of a group with pka value in this region decre ... | 1994 | 8135531 |
| identification and sequencing of pyrg, the ctp synthetase gene of azospirillum brasilense sp7. | an 18.5-kb dna fragment carrying the trpgdc cluster of azospirillum brasilense sp7 was previously cloned, yielding cosmid pab1005. attempts to identify trpa in the vicinity of trpgdc failed but led to the detection of a locus strongly homologous to pyrg, the structural gene for the ctp synthetase. the function of the a. brasilense pyrg gene was verified by complementation of the cytidine-requiring pyrg-deficient mutant jf646 of escherichia coli. a second open reading frame was identified downstr ... | 1994 | 8138139 |
| influence of ammonium and 2,4-dichlorophenoxy acetic acid on nitrogenase activity in azospirillum species from rice rhizosphere. | the influence of 2,4-dichlorophenoxy acetic acid (2,4-d) and ammonium on the nitrogenase activity of azospirillum sp. under normal fixing and low-fixing conditions was evaluated. nitrogenase activity was substantially stimulated following exposure to 2,4-d at various concentrations up to 5 ppm under normal fixing conditions. a pronounced enhancement in activity occurred with incubation. significant reduction of the nitrogenase activity occurred in the presence of nh(4+)-n at almost all concentra ... | 1994 | 7854195 |
| molecular relationship of an atypical azospirillum strain 4t to other azospirillum species. | dna/dna hybridization, plasmid content and partial 16s rdna sequence were determined to confirm the relationship between two azospirillum strains, 4b and 4t, isolated from the same rice rhizosphere. the partial 16s rdna sequence was determined for 9 strains belonging to 5 azospirillum species which included azospirillum lipoferum strains 4b and 4t, and was compared to a set of ribosomal sequences from other bacteria of the alpha subdivision of the proteobacteria. four azospirillum species sequen ... | 1994 | 7871242 |
| differences in the levels of aminoacylation and contents of modified nucleotides between total trnas from n2- and nh4(+)-grown azospirillum lipoferum cells. | total trnas isolated from n2- and nh4(+)-grown azospirillum lipoferum cells were compared with respect to amino acid acceptance, isoacceptor trna species levels and extent of nucleotide modifications. amino-acylation of these two trna preparations with ten different amino acids indicated differences in the relative acceptor activities. comparison of aminoacyl-trna patterns by rpc-5 column chromatography revealed no qualitative differences in the elution profiles. however, quantitative difference ... | 1994 | 7875713 |
| posttranslational regulation of nitrogenase activity in azospirillum brasilense ntrbc mutants: ammonium and anaerobic switch-off occurs through independent signal transduction pathways. | nitrogenase activity is regulated by reversible adp-ribosylation in response to nh4+ and anaerobic conditions in azospirillum brasilense. the effect of mutations in ntrbc on this regulation was examined. while nh4+ addition to ntrbc mutants caused a partial loss of nitrogenase activity, the effect was substantially smaller than that seen in ntr+ strains. in contrast, nitrogenase activity in these mutants was normally regulated in response to anaerobic conditions. the analysis of mutants lacking ... | 1994 | 7916012 |
| interdomain loops and conformational changes of glutamate synthase as detected by limited proteolysis. | azospirillum brasilense glutamate synthase, a complex iron-sulfur flavoprotein, was subjected to limited proteolysis using trypsin and chymotrypsin, in the absence or presence of its substrates or their analogs. time-dependent degradation of glutamate synthase alpha and beta subunits, to yield several fragments of different stability, was observed, the alpha subunit being more sensitive than the beta to proteolytic attack. the main sites of proteolytic cleavage were determined by densitometric a ... | 1994 | 8001567 |
| molecular cloning and sequencing of an operon, carrs of azospirillum brasilense, that codes for a novel two-component regulatory system: demonstration of a positive regulatory role of carr for global control of carbohydrate catabolism. | a pleiotropic carbohydrate mutant, cr17, of azospirillum brasilense rg (wild type) that assimilates c4 dicarboxylates (succinate and malate) but not carbohydrate (fructose, arabinose, galactose, glycerol, and gluconate) as c sources for growth was used to identify the car (carbohydrate regulation) locus by complementation analysis. the 2.8-kb genomic fragment that complemented the car- defect of cr17 and overlapped the fru operon (s. chattopadhyay, a. mukherjee, and s. ghosh, j. bacteriol. 175:3 ... | 1994 | 8002571 |
| sequence analysis of the azospirillum brasilense exob gene, encoding udp-glucose 4'-epimerase. | the nucleotide sequence of the azospirillum brasilense exob gene, located on plasmid prhico, has been determined. the a. brasilense exob protein shows significant homology with other prokaryotic udp-glucose 4'-epimerases (ec 5.1.3.2). | 1994 | 8026752 |
| a cdna for adenylyl sulphate (aps)-kinase from arabidopsis thaliana. | a cdna clone with an open reading frame of 831 nucleotides was isolated from a lambda zapii-library of arabidopsis thaliana. the nucleotide sequence of the cdna is homologous to the aps-kinase genes from enterobacteria, diazotrophic bacteria, and yeast: escherichia coli (cys c: 53.2%), rhizobium meliloti (nod q: 52.6%), and saccharomyces cerevisiae (met 14:57.1%). the polypeptide deduced from the plant aps-kinase cdna is comprised of 276 amino acid residues with a molecular weight of 29,790. it ... | 1994 | 8049272 |
| new osmoregulated beta(1-3),beta(1-6) glucosyltransferase(s) in azospirillum brasilense. | a linear beta(1-3),beta(1-6) glucan was detected in the periplasm of azospirillum brasilense cells growing in a medium of low osmotic strength. this glucan was produced in vitro by purified bacterial inner membranes with udp-glucose as the sugar donor in the presence of mg2+. growth in a high-osmotic-strength medium strongly reduced the amount of this glucan accumulated in the periplasmic space, and the inhibition was associated with a reduction in the enzymatic activity of the beta(1-3),beta(1- ... | 1994 | 8051002 |
| [properties of polysaccharide complexes produced by azospirillum brasilense and polysaccharides isolated from these complexes]. | azospirillum brasilense strains sp7, sp7 (s-form), sp107, sp245, sp246, s17, and 15 when cultivated in a liquid synthetic malate medium up to the end of the logarithmic phase of growth were shown to produce at least two complex polysaccharide-containing components. the components were arbitrarily called lipopolysaccharide-protein complex (lppc) and polysaccharide-lipid complex (pslc). the lppcs and pslcs from the strains sp7, sp107, sp245, sp246, and s17 were shown to interact with a wheat germ ... | 1994 | 7760764 |
| cloning and characterization of a cluster of genes coding for 5s rrna and three trnas from azospirillum lipoferum. | a genomic library was constructed from a hindiii digest of azospirillum lipoferum chromosomal dna in the hindiii site of puc19. from the library, a clone, palh64, which showed strong hybridization with 3' end labeled a. lipoferum total trnas and which contains a 2.9 kb insert was isolated and restriction map of the insert established. the nucleotide sequence of a 490 bp hindiii-hincii subfragment containing a cluster of genes coding for 5s rrna, trna(val)(uac), trna(thr)(uga) and trna(lys)(uuu) ... | 1994 | 7526923 |
| the ntrbc genes of azospirillum brasilense are part of a nifr3-like-ntrb-ntrc operon and are negatively regulated. | a cosmid able to complement the nif- and nitrate-dependent growth phenotypes of the azospirillum brasilense mutant fp9 was isolated from a genomic library of the wild-type strain fp2. a 6-kb dna region was sequenced and showed two open reading frames (orfs) identified as the ntrb and ntrc genes. an orf1 located upstream from the ntrb gene and coding for a 36-kda polypeptide showed similarity to the nifr3 gene of rhodobacter capsulatus and the orf1 of rhizobium leguminosarum, both located upstrea ... | 1995 | 7553451 |
| cloning, sequencing, and phenotypic analysis of laf1, encoding the flagellin of the lateral flagella of azospirillum brasilense sp7. | azospirillum brasilense can display a single polar flagellum and several lateral flagella. the a. brasilense sp7 gene laf1, encoding the flagellin of the lateral flagella, was isolated and sequenced. the derived protein sequence is extensively similar to those of the flagellins of rhizobium meliloti, agrobacterium tumefaciens, bartonella bacilliformis, and caulobacter crescentus. an amino acid alignment shows that the flagellins of these bacteria are clustered and are clearly different from othe ... | 1995 | 7559324 |
| synthesis of phytohormones by plant-associated bacteria. | the plant hormones, auxins and cytokinins, are involved in several stages of plant growth and development such as cell elongation, cell division, tissue differentiation, and apical dominance. the biosynthesis and the underlying mechanism of auxins and cytokinins action are subjects of intense investigation. not only plants but also microorganisms can synthesize auxins and cytokinins. the role of phytohormone biosynthesis by microorganisms is not fully elucidated: in several cases of pathogenic f ... | 1995 | 7576148 |
| the two overlapping azospirillum brasilense upstream activator sequences have differential effects on nifh promoter activity. | the azospirillum brasilense nifh promoter is positively controlled by the nifa protein bound to the upstream activator sequences (uass). two overlapping uass located at -191 and -182 were identified with the consensus tgt-n10-aca motif. the role of the two uass of azospirillum brasilense nifh promoter was examined by introducing base substitutions in the nifa binding sites. both the promoter down phenotype of a mutation in uas2 and increased activation when uas1 was mutated reveal that the integ ... | 1995 | 7585362 |
| phylogeny of the genus azospirillum based on 16s rdna sequence. | the 16s rdna of 17 strains of azospirillum, 14 assigned to one of the known species a. amazonense, a. brasilense, a. halopraeferens, a. irakense and a. lipoferum, and the other three of uncertain taxonomic position, was sequenced after polymerase chain reaction amplification and analysed in order to investigate the phylogenetic relationships at the intra-generic and super-generic level. the phylogenetic analysis confirms that the genus azospirillum constitutes a phylogenetically separate entity ... | 1995 | 7607400 |
| a mutant of azospirillum brasilense sp7 impaired in flocculation with a modified colonization pattern and superior nitrogen fixation in association with wheat. | we report here significant phenotypic and genetic differences between azospirillum brasilense sp7 and spontaneous mutant sp7-s and their related properties in association with wheat. in contrast to the wild-type strain of sp7, colonies of sp7-s stained weakly with congo red when grown on agar media containing the dye and did not flocculate in the presence of fructose and nitrate. scanning and transmission electron micrographs showed clearly that the sp7-s strain lacked surface materials present ... | 1995 | 7646034 |
| carbapenem antibiotic production in erwinia carotovora is regulated by carr, a homologue of the luxr transcriptional activator. | strain gs101 of erwinia carotovora makes the carbapenem antibiotic, 1-carbapen-2-em-3-carboxylic acid. mutants defective in antibiotic production can be assigned to two groups, group 1 and group 2. group 2 mutants are defective in the carl gene encoding a protein responsible for synthesis of the lux autoinducer n-(3-oxohexanoyl)-l-homoserine lactone (ohhl), which is required to induce carbapenem synthesis in strain gs101. in this paper we describe the molecular genetic analysis of the group 1 mu ... | 1995 | 7711893 |
| existence of two ferredoxin-glutamate synthases in the cyanobacterium synechocystis sp. pcc 6803. isolation and insertional inactivation of gltb and glts genes. | the first two genes of ferredoxin-dependent glutamate synthase (fd-gogat) from a prokaryotic organism, the cyanobacterium synechocystis sp. pcc 6803, were cloned in escherichia coli. partial sequencing of the cloned genomic dna, of the 6.3 kb hind iii and 9.3 kb cla i fragments, confirmed the existence of two different genes coding for glutamate synthases, named gltb and glts. the gltb gene was completely sequenced and encodes for a polypeptide of 1550 amino acid residues (m(r) 168,964). compara ... | 1995 | 7727752 |
| comparison studies of dinitrogenase reductase adp-ribosyl transferase/dinitrogenase reductase activating glycohydrolase regulatory systems in rhodospirillum rubrum and azospirillum brasilense. | reversible adp ribosylation of dinitrogenase reductase, catalyzed by the dinitrogenase reductase adp-ribosyl transferase (drat)/dinitrogenase reductase activating glycohydrolase (drag) regulatory system, has been characterized in both rhodospirillum rubrum and azospirillum brasilense. although the general functions of drat and drag are very similar in these two organisms, there are a number of interesting differences, e.g., in the timing and extent of the regulatory response to different stimuli ... | 1995 | 7730264 |
| genetic diversity of n2-fixing bacteria associated with rice roots by molecular evolutionary analysis of a nifd library. | the rhizosphere of wetland rice has significant n2-fixing activity. it has been suggested that n2 fixation in the rice root zone is associated with the activity of various n2-fixing heterotrophic bacteria that inhabit the rice rhizosphere. because of the generic diversity, many different isolation media and conditions are required to count and isolate these bacteria. in an attempt to overcome any bias from culture-dependent methods we amplified nifd segments from crude rice root dna by the polym ... | 1995 | 7736355 |
| identification of azospirillum strains by restriction fragment length polymorphism of the 16s rdna and of the histidine operon. | dna fingerprints of several azospirillum strains, belonging to the five known species a. amazonense, a. brasilense, a. halopraeferens, a. irakense and a. lipoferum, were obtained by restriction analysis of the amplified 16s rdna and by restriction fragment length polymorphism of the histidine biosynthetic genes. data obtained showed that amplified rdna restriction analysis is an easy, fast, reproducible and reliable tool for identification of azospirillum strains, mainly at the species level, wh ... | 1995 | 7737487 |
| effects of 2,4-dichlorophenoxyacetic acid on polyamine transport and metabolism in azospirillum brasilense cd. | we had previously demonstrated that 1 mm 2,4-d inhibited cell growth, nucleic acid synthesis and protein synthesis (at the ribosomal level) of azospirillum brasilense. these alterations were prevented by the presence of polyamines in the culture medium. on the other hand, polyamines did not affect the 2,4-d uptake. in this paper we demonstrate that 2,4-d alters the metabolism of polyamines and increases their uptake. | 1995 | 7740550 |
| isolation and characterization of a locus from azospirillum brasilense sp7 that complements the tumorigenic defect of agrobacterium tumefaciens chvb mutant. | the chromosomal virulence gene chvb of agrobacterium tumefaciens is required for pathogenesis. a dna fragment from the chvb locus can hybridize to dna from azospirillum brasilense sp7. this dna fragment could restore the tumorigenic activity of the chvb mutant strain a. tumefaciens a1011 towards leaf disks of nicotiana tabacum. an nh2-terminal open reading frame, 480 codons long, was most likely responsible for the restoration of the tumorigenic activity. the a. brasilense sequence showed good h ... | 1995 | 7756697 |
| pulsed-field gel electrophoresis fingerprinting for identification of azospirillum species. | pulsed-field gel electrophoresis (pfge) was used to obtain macrorestriction fingerprints of restriction enzyme-cut dna of natural isolates of azospirillum spp. metabolic profiles, along with other phenotypic characteristics, were compared with these fingerprints to differentiate among the azospirilla isolates. a wide diversity of phenotypes (e.g., colony color, motility, and accumulation of poly-beta-hydroxybutyrate granules) was observed among the natural isolates of azospirilla. pfge revealed ... | 1995 | 7765845 |
| cloning wild-type chromosomal genes using transposon mutagenized dna in gram-negative bacteria. | 1995 | 7482783 | |
| [cloning and sequencing of ntrbc genes from azospirillum brasilense]. | a gene library of azospirillum brasilense yu62 was constructed in embl3. the library was screened with pcr amplified fragment as a special probe. ten positive plaques (ea1-ea10) were selected. detection results showed they contained two different types of clones, representing as ea4 and ea9 respectively. southern hybridization of ea4 displayed that target gene was located in a 2.9kb ecori fragment. sequence of this fragment had allowed the position and identification of ntrc gene, which encoding ... | 1995 | 7483580 |
| cloning and sequencing of the putative azospirillum brasilense gene encoding gtp cyclohydrolase ii. | sequence analysis of a fragment of azospirillum brasilense dna revealed the presence of a riba homologue, of which the 3' portion encodes a putative gtp cyclohydrolase ii. the 5' portion (approx. half of the orf) does not show homology to any other sequence from the databases. | 1995 | 7883178 |
| effect of herbicides on nitrogen fixation (c2h2 reduction) associated with rice rhizosphere. | in a field study nitrogenase activity associated with rice rhizosphere was differently influenced by the applied herbicides. pretilachlor at two application levels had no effect on nitrogenase activity while butachlor and benthiocarb exerted marginal stimulation. cinmethylin consistently stimulated nitrogenase activity throughout the plant growth period. anilofos when applied singly had no substantial effect on nitrogenase activity but in combination with 2,4-d the activity was enhanced. populat ... | 1995 | 7874477 |
| carrs of azospirillum brasilense is homologous to a large family of aldehyde dehydrogenases rather than to two-component regulators. | 1995 | 8525059 | |
| oligonucleotide probes based on 16s rrna sequences for the identification of four azospirillum species. | partial sequences of the 16s rrna molecules of nine strains belonging to four azospirillum species were used to design species-specific oligonucleotide probes. azospirillum strains sequences were analyzed and three homologous fragments containing 16 nucleotides were determined. these three probes were found to be characteristic of a. lipoferum (al), a. irakense (ai), and a. brasilense/amazonense species (aba) and of few nontarget organisms. the specificity of these three probes was tested both a ... | 1995 | 8542552 |
| [growth and survival of azospirillum in roots and maize rhizospheres with different levels of acidity]. | an experiment was carried out in order to evaluate the effect of ph on azospirillum sp. growth and survival in maize rhizosphere. sterilized maize seeds were sown in a perlite substratum with addition of a nutritive medium. the pots were buffered at two different phs: 5.8 (group one) and 7.0 (group two). each group was divided in two treatments: inoculated with azospirillum sp. az-39 and non-inoculated. experimental pots were incubated at 20 degrees c with a 14 hour photoperiod. growth of non-in ... | 1995 | 8552763 |
| molecular characterization of rhizosphere and clinical isolates of burkholderia cepacia. | four burkholderia cepacia strains isolated from the rhizosphere and pathological samples of infected human patients were characterized at the molecular level by different methodologies, including the determination of 16s ribosomal rdna sequence, restriction endonuclease analysis of total dna, random amplified polymorphic dna fingerprinting and southern hybridization with gene probes for nitrogen fixation and siderophore synthesis. the results indicate that the four strains cluster together withi ... | 1995 | 8577994 |
| in situ localization of azospirillum brasilense in the rhizosphere of wheat with fluorescently labeled, rrna-targeted oligonucleotide probes and scanning confocal laser microscopy. | the colonization of wheat roots by azospirillum brasilense was used as a model system to evaluate the utility of whole-cell hybridization with fluorescently labeled, rrna-targeted oligonucleotide probes for the in situ monitoring of rhizosphere microbial communities. root samples of agar- or soil-grown 10- and 30-day-old wheat seedlings inoculated with different strains of a. brasilense were hybridized with a species-specific probe for a. brasilense, a probe hybridizing to alpha subclass proteob ... | 1995 | 16534951 |
| comparative study of substrates and inhibitors of azospirillum lipoferum and pyricularia oryzae laccases. | azospirillum lipoferum and pyricularia oryzae laccases were compared, using several substrates and inhibitors. sixteen phenolic or nonphenolic compounds were found to be substrates of both fungal and bacterial laccases. in the presence of different phenol oxidase inhibitors, p. oryzae and a. lipoferum laccase activities had similar properties. | 1995 | 16534964 |
| survival of azospirillum brasilense in the bulk soil and rhizosphere of 23 soil types. | the survival of azospirillum brasilense cd and sp-245 in the rhizosphere of wheat and tomato plants and in 23 types of plant-free sterilized soils obtained from a wide range of environments in israel and mexico was evaluated. large numbers of a. brasilense cells were detected in all the rhizospheres tested, regardless of soil type, bacterial strain, the origin of the soil, or the amount of rainfall each soil type received prior to sampling. survival of a. brasilense in soils without plants diffe ... | 1995 | 16535030 |
| the development of azospirillum as a commercial inoculant for improving crop yields. | bacteria of the genus azospirillum are nitrogen-fixing organisms that live in close association with plants in the rhizosphere. the azospirillum-plant association leads to the enhanced development and yield of different host plants under appropriate growth conditions. this increase in yield is attributed mainly to an improvement in root development, an increase in the rate of water and mineral uptake by roots, and to a lesser extent, biological n(2) fixation. worldwide data accumulated in the fi ... | 1995 | 14536095 |
| spectroscopic characterization of mineral crystals produced by the bacterium azospirillum brasilense. | the results of spectroscopic structural and trace elemental analyses of mineral crystals produced by the soil nitrogen-fixing bacterium azospirillum brasilense cultivated in a synthetic medium are presented and discussed. the mineral formed is shown to have a structure close to struvite (mgnh(4)po(4) x 6h(2)o; astm file no. 15-762) with some differences which may be attributed to the presence of isomorphic admixtures of other cations (struvite is known to have a variety of forms). aas/aes and io ... | 1996 | 15045359 |
| promotion of nod gene inducers and nodulation in common bean (phaseolus vulgaris) roots inoculated with azospirillum brasilense cd. | inoculation of phaseolus vulgaris with azospirillum brasilense cd promoted root hair formation in seedling roots and significantly increased total and upper nodule numbers at different concentrations of rhizobium inoculum. in experiments carried out in a hydroponic system, a. brasilense caused an increase in the secretion of nod gene-inducing flavonoids, as was observed by nod gene induction assays of root exudates fractionated by high-performance liquid chromatography. possible mechanisms invol ... | 1996 | 16535388 |
| 2,4-dichlorophenoxyacetic acid affects the attachment of azospirillum brasilense cd to maize roots. | 2.4-dichlorophenoxyacetic acid (2,4-d) is a herbicide widely applied to forage, grain and cereals. we previously determined that 1 mm 2,4-d diminished cell growth and cellular activity of azospirillum brasilense cd. the present work was designed to determine the possible effect of this herbicide--at concentrations used on crops--on the attachment of the bacteria to maize roots, since this step is of prime importance for the growth stimulation of the plant obtained with azospirillum brasilense. i ... | 1996 | 8597034 |
| characterization of 2,4-dichlorophenoxyacetic acid transport and its relationship with polyamines in azospirillum brasilense. | we have previously shown that 2,4-dichlorophenoxyacetic acid (2,4-d) inhibits azospirillum brasilense growth, the synthesis of dna, rna and proteins. these toxic effects are prevented when polyamines are added to the culture medium. the purposes of our research were to determine the effects of the herbicide on the number of viable azospirillum brasilense cells, characterize the 2,4-d transport system and to study the effects of polyamines upon the latter in this microorganism. we found that 2,4- ... | 1996 | 8597175 |
| cloning, sequencing and transcriptional regulation of the drat and drag genes of azospirillum lipoferum fs. | from azospirillum lipoferum (al) fs, a nitrogen-fixing bacterium isolated from the rhizosphere of rice, we cloned and sequenced drat, encoding dinitrogenase reductase adp-ribosyltransferase, and drag, encoding dinitrogenase reductase-activating glycohydrolase. the nucleotide sequences of dratg showed extensive similarity to the same genes from azospirillum brasilense, rhodospirillum rubrum and rhodobacter capsulatus, and they are assumed to be co-transcribed as a single operon. when this dratg o ... | 1996 | 8621068 |
| presence of a second mechanism for the posttranslational regulation of nitrogenase activity in azospirillum brasilense in response to ammonium. | although adp-ribosylation of dinitrogenase reductase plays a significant role in the regulation of nitrogenase activity in azospirillum brasilense, it is not the only mechanism of that regulation. the replacement of an arginine residue at position 101 in the dinitrogenase reductase eliminated this adp-ribosylation and revealed another regulatory system. while the constructed mutants had a low nitrogenase activity, nh4+ still partially inhibited their nitrogenase activity, independent of the dini ... | 1996 | 8631686 |
| the azospirillum brasilense rpon gene is involved in nitrogen fixation, nitrate assimilation, ammonium uptake, and flagellar biosynthesis. | the rpon (ntra) gene (encoding sigma 54) of azospirillum brasilense sp7 was isolated by using conserved rpon primers and the polymerase chain reaction, and its nucleotide sequence was determined. the deduced amino acid sequence of the rpon protein was found to share a high degree of homology with other members of the sigma 54 family. two additional open reading frames were found in the azospirillum brasilense rpon region, with significant similarity to equivalent regions surrounding the rpon loc ... | 1996 | 8640606 |
| isolation and characterization of azospirillum lipoferum locus that complements rhizobium meliloti dcta and dctb mutations. | a dna probe containing the structural gene for dicarboxylate transport (dct a) of rhizobium meliloti hybridized strongly with the fragments of azospirillum lipoferum genomic dna. a genomic library of a. lipoferum was screened for the dct a gene by complementation of a dct a mutant of rhizobium meliloti. a recombinant cosmid, p37d, capable of restoring growth of the dct a mutant on dicarboxylates was isolated and found to hybridize to the dcta probe. the ability of p37d to complement the dct b mu ... | 1996 | 8640608 |
| cloning, nucleotide sequencing, and expression of the azospirillum brasilense lon gene: involvement in iron uptake. | the lon gene of escherichia coli encodes the lon (la) protease, which is associated with cellular protein degradation. a lon gene homolog from azospirillum brasilense, a nitrogen-fixing soil bacterium which lives in association with the roots of cereal grasses, was cloned and characterized. the nucleotide sequence of the a. brasilense lon gene was determined. it contains an open reading frame that encodes a protein of 810 amino acids with a predicted molecular mass of about 90 kda. the deduced a ... | 1996 | 8655539 |
| properties of the recombinant beta subunit of glutamate synthase. | glutamate synthase is a complex iron-sulfur flavoprotein containing one molecule each of fad and fmn and three distinct iron-sulfur centers/alpha beta protomer. production of the beta subunit was observed in total extracts of escherichia coli bl21 (de) cells harbouring a pt7-7 derivative carrying gltd, the gene encoding the azospirillum brasilense glutamate synthase beta subunit. the protein was soluble, and the identity of the purified protein with the azospirillum glutamate synthase beta subun ... | 1996 | 8665916 |
| glutamate synthase: a complex iron-sulphur flavoprotein. | 1996 | 8674779 | |
| surface properties and motility of rhizobium and azospirillum in relation to plant root attachment | plant growth promotion by rhizobacteria is a widely spread phenomenon. however only a few rhizobacteria have been studied thoroughly. rhizobium is the best-studied rhizobacterium. it forms a symbiosis with a restricted host range. azospirillum is another plant-growth-promoting rhizobacterium which forms rhizocoenoses with a wide range of plants. in both bacteria, the interaction with the plant involves the attraction toward the host plant and the attachment to the surface of the root. both bacte ... | 1996 | 8688006 |
| oxygen taxis and proton motive force in azospirillum brasilense. | the microaerophilic nitrogen-fixing bacterium azospirillum brasilense formed a sharply defined band in a spatial gradient of oxygen. as a result of aerotaxis, the bacteria were attracted to a specific low concentration of oxygen (3 to 5 microm). bacteria swimming away from the aerotactic band were repelled by the higher or lower concentration of oxygen that they encountered and returned to the band. this behavior was confirmed by using temporal gradients of oxygen. the cellular energy level in a ... | 1996 | 8752338 |
| modulation of nifa activity by pii in azospirillum brasilense: evidence for a regulatory role of the nifa n-terminal domain. | azospirillum brasilense nifa, which is synthesized under all physiological conditions, exists in an active or inactive from depending on the availability of ammonia. the activity also depends on the presence of pii, as nifa is inactive in a glnb mutant. to investigate further the mechanism that regulates nifa activity, several deletions of the nifa coding sequence covering the amino-terminal domain of nifa were constructed. the ability of these truncated nifa proteins to activate the nifh promot ... | 1996 | 8759845 |
| expression of the structural gene, laf1, encoding the flagellin of the lateral flagella in azospirillum brasilense sp7. | the induction of the lateral flagella of azospirillum brasilense sp7 was studied by using a translational fusion between the laf1 promoter and gusa. the fusion was induced when cells were grown on solid media but not when they were grown in broth. the fusion was also induced by incubation of liquid-grown cells with an anti-polar flagellum polyclonal antiserum. hindrance of polar-flagellum rotation is suggested to be the signal for this induction. | 1996 | 8759869 |
| acyl carrier protein of azospirillum brasilense: properties of the purified protein and sequencing of the corresponding gene, acpp. | acyl carrier protein (acp) plays a crucial role in bacterial fatty acid synthesis. cloning genes encoding acps from gram-negative bacteria in escherichia coli is difficult due to adverse effects of the cloned gene on host cell viability, and we were unsuccessful in cloning the full length acp gene (acpp) from azospirillum brasilense using conventional methods. therefore, acp from a. brasilense was purified to homogeneity and a part of the acpp gene was cloned using the polymerase chain reaction ... | 1996 | 8760922 |
| coexistence of two structurally similar but functionally different pii proteins in azospirillum brasilense. | the coexistence of two different pii, proteins in azospirillum brasilense was established by comparing proteins synthesized by the wild-type strain and two null mutants of the characterized glnb gene (encoding pii) adjacent to glna. strains were grown under conditions of nitrogen limitation or nitrogen excess. the proteins were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (sds-page) or isoelectric focusing gel electrophoresis and revealed either by [32p]phosphate or [3h] ... | 1996 | 8763942 |
| cloning and functional analysis of the pmma gene encoding phosphomannomutase from the photosynthetic prokaryote prochlorothrix hollandica. | the pmma gene encoding a bifunctional phosphomannomutase/phosphoglucomutase (pmm/pgm) from the photosynthetic prokaryote, prochlorothrix hollandica has been cloned and sequenced. the gene encodes a 51827 da polypeptide 48% identical to the pmm of azospirillum brasilense, 37% identical to the pgms of pathogenic neisseria sp. and 37% identical to the bifunctional algc pgm/pmm of pseudomonas aeruginosa. the pmma gene encodes an enzyme having both pgm and pmm activities as judged by both enzyme assa ... | 1996 | 8765122 |
| the sodium-driven polar flagellar motor of marine vibrio as the mechanosensor that regulates lateral flagellar expression. | certain marine vibrio species swim in sea water, propelled by a polar flagellum, and swarm over surfaces using numerous lateral flagella. the polar and the lateral flagellar motors are powered by sodium- and proton-motive forces, respectively. the lateral flagella are produced in media of high viscosity, and the relevant viscosity sensor is the polar flagellum. the cell might monitor either the rotation rate of the flagellar motor or the mechanical force applied against the flagellum. to test th ... | 1996 | 8793868 |
| production and characterization of strain-specific monoclonal antibodies against outer membrane components of azospirillum brasilense sp245. | several hybridoma cell lines producing murine monoclonal antibodies (mabs) directed against outer membrane components of the gram-negative rhizosphere bacterium azospirillum brasilense sp245 have been established and characterized. whole bacterial cells were used as immunogens. among the clones obtained, 14 hybridoma cell lines were selected for further characterization. eight mabs were strain-specific and 6 mabs showed cross-reactivity with a closely related strain azospirillum brasilense sp246 ... | 1996 | 8823621 |
| purification and properties of aromatic amino acid aminotransferases from azospirillum brasilense uap 14 strain. | the purification and characterization of aat1, one of two aromatic amino acid aminotransferase (ec 2.6.1.57) in azospirillum brasilense, is described. purified aat1 had a subunit mass of 33 kda and a nondenatured molecular mass of 66 kda, suggesting a dimeric structure. other properties include a pi of 5.04, an optimum temperature of 45 degrees c, and optimum ph of 8.5. aat1 utilized all aromatic amino acids, the l-tryptophan derivatives such as l-5-methyl tryptophan and l-flour-tryptophan, and ... | 1996 | 8868238 |
| osmoadaptation by rhizosphere bacteria. | the osmolality of rhizosphere soil water is expected to be elevated in relation to bulk-soil water osmolality as a result of the exclusion of solutes by plant roots during water uptake, the release of plant root exudates, and the production of exopolymers by plant roots and rhizobacteria. in contrast, the osmolality of water within highly hydrated bulk soil is low (less than 50 osm/kg); thus the ability to adapt to elevated osmolality is likely to be important for successful rhizosphere coloniza ... | 1996 | 8905077 |
| characterization of a novel spirillum-like bacterium that degrades ferrioxamine-type siderophores. | a novel gram-negative spirillum-like bacterium (asp-1) was isolated from lake water by enrichment culture on desferrioxamine b as sole source of carbon and energy. asp-1 was able to degrade the siderophores desferrioxamine b and e. the property of siderophore degradation was inducible in the presence of desferrioxamine b. the ferric complexes, however, were not measurably degraded but served as an iron source. degradation of desferrioxamines in culture was followed by measuring the residual ferr ... | 1996 | 8574095 |
| azospirillum lipoferum trnas: fractionation and identification of trna species and the nucleotide sequence of trna(asn) (quu). | transfer rnas of azospirillum lipoferum were separated by two-dimensional gel electrophoresis and identified by aminoacylation. thirty-six trna spots were resolved by this technique and twenty-six trna species have been identified. there are five trnas for leu, four for val, three for pro, two each for arg, ile, lys and tyr, and one each for ala, asp, his, phe, ser and thr. the trna (asn) (quu) was purified and its nucleotide sequence was determined. the a. lipoferum trna (asn) (quu) is 92% simi ... | 1996 | 8988334 |
| cloning and sequencing of the nitrogenase structural genes nifhdk of herbaspirillum seropedicae. | the nitrogenase structural genes (nifhdk) of the endophytic diazotroph herbaspirillum seropedicae were isolated from a genomic bank by plate hybridization. sequence analysis of the dna showed a consensus promoter region upstream for the nifh gene containing a -24/-12 type promoter together with nifa- and integration host factor (ihf)- binding sites. the derived protein sequences of nifh, nifd and nifk contained conserved cysteine residues for binding iron-sulfur clusters and the iron-molybdenum ... | 1996 | 9222418 |
| regulation of nitrogen fixation in azospirillum brasilense. | the regulation of nitrogen fixation in azospirillum brasilense is very complicated, and it responds to exogenous fixed nitrogen or a change of oxygen concentration. this regulation occurs at both transcriptional and posttranslational levels. unlike regulation seen in klebsiella pneumoniae, transcription of nifa does not require ntrb/ntrc in a. brasilense and the expression of nifhdk is controlled by posttranslational regulation of nifa activity. addition of nh4+ or a shift from microaerobic to a ... | 1997 | 9231412 |
| site-specific endonuclease abai from azospirillum brasilense uq 1796 is an isoschizomer of endonuclease bcli. | the site-specific endonuclease abai was isolated and purified to functional purity from the soil nitrogen-fixing bacterium azospirillum brasilense uq 1796. purification included successive chromatography on columns with phosphocellulose, heparin-sepharose, and hydroxyapatite. the purified enzyme recognizes the palindromic dna sequence 5'-t decreases atca-3' and cleaves it as shown by the arrow. the isolated enzyme belongs to class ii restriction endonuclease and is an isoschizomer of endonucleas ... | 1997 | 9275272 |
| how do bacteria avoid high oxygen concentrations? | bacteria, such as escherichia coli and azospirillum brasilense, avoid microenvironments with elevated oxygen concentrations, not by sensing reactive oxygen derivatives, but by sensing a metabolic down-shift that results from elevated oxygen levels. a novel protein, aer, and the chemotaxis serine receptor, tsr, have recently been identified as transducers for aerotaxis which monitor internal energy levels in the bacteria. | 1997 | 9337487 |
| [effect of the fungicide captan on azospirillum brasilense cd in pure culture and associated with setaria italica]. | the effect of fungicide captan on growth and nitrogenase activity of azospirillum brasilense cd was studied in pure cultures and in association with foxtail millet (setaria italica) cultivar carapé under laboratory conditions. the 8 h growth in rotary shaker of a. brasilense was inhibited with 1 mg/l pure captan; however, after 4 days the differences diminished compared with the control without captan. nitrogenase activity was affected with 10 mg/l but the differences were negligible after 48 h ... | 1997 | 9411490 |
| [effect of inoculation with azospirillum spp on forage grasses in highland pastures of the sierras de córdoba, argentian]. | a field assay was performed in an impoverished hill grassland of the sierras of córdoba, with the objective of evaluating the effects of azospirillum spp on gramineous plants. native grasses were inoculated with different strains of azospirillum lipoferum and azospirillum brasilense, during two consecutive years. the inoculation effect on yield, nitrogen content and number of azospirillum spp was evaluated in three annual harvests. the first and the second inoculation increased significantly the ... | 1997 | 9424624 |
| cloning and sequencing of dratg genes and their downstream region of azospirillum brasilense yu62. | an 8-kb fragment was cloned by probing the gene library of azospirillum brasilense yu62 with the 4.0-kb dratg fragment of a. brasilense sp7. dna hybridization of this fragment demonstrated that dratg genes were located in a 3.0-kb ecor i-kpn i fragment, and were contiguous to the nifh gene. this 3.0-kb fragment was completely sequenced on both strands. sequence analysis of the fragment revealed that it included the full-length dratg genes and two orfs downstream of drag (orf3 and incomplete orf4 ... | 1997 | 9429775 |
| spectroscopic characterization of the uptake of essential and xenobiotic metal cations in cells of the soil bacterium azospirillum brasilense. | the results of flame (faas) or graphite furnace atomic absorption spectrometric (gfaas) analyses are presented and discussed on the accumulation of essential metals (mg, ca, mn and fe contained in the cultivation medium) and traces of each one of the conventionally xenobiotic elements from the group v, co, ni, cu, zn or pb, added to the medium in concentrations (0.2 mm) which do not essentially suppress growth of the bacterial culture, in cells of the plant root-associated nitrogen-fixing bacter ... | 1997 | 9043641 |
| characterization and application of a strain-specific monoclonal antibody against the rhizosphere bacterium azospirillum brasilense wa5. | a hybridoma cell line producing a rat monoclonal antibody (mab bo-33) directed against lipopolysaccharide of azospirillum brasilense wa5 has been established and characterized. whole bacteria were used as immunogens. the number of antigens per cell was about 1500. the number of antigens per cell of reisolates from the rhizosphere of what was similar to the number of antigens of bacteria cultivated in rich medium. the sensitivity of detection using mab bo-33 was about 100 bacteria/ml. therefore, ... | 1997 | 9145321 |
| oxygen sensitivity of nifa protein of azospirillum lipoferum fs as suggested by gene cloning and expression in escherichia coli. | we cloned and sequenced a 2.8-kb sali fragment of azospirillum lipoferum fs as a homologue of the klebsiella oxytoca nifa gene. the amino acid sequence deduced from an open reading frame of 1872 bases showed 91% identity to that of the a. brasilense nifa, and the putative central sigma54 interaction domain was conserved as well as the c-terminal dna-binding domain. the nifa function on the nifh promoter was examined in escherichia coli using a combination of a nifa driver plasmid and a nifh-lacz ... | 1997 | 9178550 |
| [nucleotide sequence of gltb gene encoding the large subunit of rhodobacter sphaeroides glutamate synthase]. | the complete nucleotide sequence of a 5.4-kb chromosomal ecori-sali fragment was determined, which contains the structural gene (gltb) for the large subunit of rhodobacter sphaeroides glutamate synthase, as well as the 5'- and 3'- flanking regions. a open reading frame of 4636 base pairs was identified as r. sphaeroides gltb gene. the mw of the large subunit, as deduced from the nucleotide sequence, was estimated as 164kd. comparision of the nucleotide sequences revealed a high similarity among ... | 1997 | 9863198 |
| sequencing and analysis of function of the promoter region of dratg genes from azospirillum brasilense yu62. | from azospirillum brasilense yu62, we cloned and sequenced the upstream region of dratg. no identified genes were found in this region except for portion of nifh, which is transcribed divergently from dratg. however, some potential regulatory elements were found, which include downstream promoter elements (dpe), upstream activator sequences (uas), and a + t-rich regions. this suggests that the region between drat and nifh might be a regulatory region rather than an encoding region, and the promo ... | 1997 | 9631255 |
| isolation and characterization of the azospirillum brasilense trpe(g) gene, encoding anthranilate synthase. | the azospirillum brasilense trpe gene has been isolated by dna hybridization and by genetic complementation of an escherichia coli trpe deletion mutant. dna sequence analysis of a 3.1-kb psti restriction fragment of a. brasilense revealed the presence of an open reading frame encoding a putative trpe(g) fusion protein. previously an a. brasilense clone containing trpgdc was identified (zimmer et al. mol gen genet 229:41-51, 1991). it can, therefore, be concluded that a. brasilense contains two t ... | 1997 | 8939798 |
| phylogenetic relationships of the helical-shaped bacteria in the alpha proteobacteria inferred from 16s rdna sequences. | 16s ribosomal rna gene sequences from seven strains of aquaspirillum peregrinum, aqu. itersonii, aqu. polymorphum, and oceanospirillum pusillum were compared with homologous sequences from other members of helical-shaped bacteria. the bootstrapped neighbor-joining tree, inferred from 887 aligned sites, placed the spirillum taxa assigned to aquaspirillum, oceanospirillum, azospirillum, magnetospirillum, rhodospirillum, and rhodocista of the proteobacteria in seven clusters of alpha proteobacteria ... | 1997 | 12501339 |
| biodegradation and plant protection from the herbicide 2,4-d by plant-microbial associations in cotton production systems. | a significant "biosafening" protection of plants from the effect of 2,4-d in plant-microbial associations has been demonstrated in this study. the 2,4-d-degrading plasmid, pjp4 was transferred into rhizobium sp. cb1024, which nodulates dolichos lablab, and azospirillum brasilense sp7 carrying a nifa-lacz gene marker, which can colonize cotton roots. both transconjugants degraded 2,4-d in pure culture via cometabolism up to 50 microg ml(-1). when the transconjugants were inoculated onto dolichos ... | 1997 | 18636407 |
| the nucleotide sequence of gltd gene encoding the small subunit of rhodobacter sphaeroides glutamate synthase. | we have determined the complete nucleotide sequence of a 2 387 bp chromosomal sali-ecori fragment, which contains the structural gene (gltd) for the small subunit of rhodobacter sphaeroides glutamate synthase, as well as the 5'- and 3'-flanking regions. an open reading frame of 1 242 base pairs was identified as the r. sphaeroides gltd gene. the mw of the small subunit, as deduced from the nucleotide sequence, was estimated to be 44 kd. a comparison of the nucleotide sequence revealed a high sim ... | 1997 | 12219208 |
| dinitrogen fixation of microbe-plant associations as affected by nitrate and ammonium supply. | abstract the dinitrogen fixation activity of azospirillum sp., and pantoea agglomerans strains was determined by (15)n(2) incorporation after incubation with (15)n(2) labeled air or/and by acetylene reduction. these bacterial strains were able to fix n(2) both in pure culture and in association with wheat plants in hydroponics. nitrogenase activity of azospirillum sp., in pure culture was more rapidly inhibited by the addition of nh(4) (+) than no(3) (-). the n(2) fixation of p. agglomerans de ... | 1997 | 22087483 |
| involvement of a 120-mda plasmid of azospirillum brasilense sp245 in the production of lipopolysaccharides. | using omegon-km mutagenesis, six azospirillum brasilense sp245 mutant derivatives lacking the capability to synthesize either one of the two major o-specific polysaccharides (o-pss) were constructed in vivo. in all of the lps mutants obtained, single omegon-km insertions were shown to be located on an indigenous plasmid dna with molecular weight 120 mda (p120). physical and immunochemical analyses revealed two p120 loci coding for o-psi and two p120 loci involved in the production of o-psii. one ... | 1998 | 9657936 |
| variation in nitrogen fixing ability among natural isolates of azospirillum | 1998 | 9688781 | |
| aggregation in azospirillum brasilense: effects of chemical and physical factors and involvement of extracellular components. | a medium for consistent induction of aggregation of azospirillum brasilense cells was developed and used to study the effects of chemical and physical factors as well as extracellular components involved in this phenomenon. growth of a. brasilense strain cd in a high c:n medium using fructose and ammonium chloride as c and n sources, respectively, resulted in flocculation visible to the naked eye after 24 h. no cell aggregates were formed after 72 h growth in low c:n medium. aggregating cells, b ... | 1998 | 9695932 |
| structural homologues p(ii) and p(z) of azospirillum brasilense provide intracellular signalling for selective regulation of various nitrogen-dependent functions. | p(ii) (glnb) is a signal transduction protein that in azospirillum brasilense is specifically required for nitrogen fixation. little is known about whether and how its homologue p(z) (glnz) participates in the regulation of cellular functions. in this study, we have shown the regulatory action of the two proteins by analysing the relevant single and double null-mutant strains. the transcription of glnz is monocistronic, and it starts mainly from a sigma54-dependent promoter, activated by ntrc. g ... | 1998 | 9720864 |
| heterologous gene expression in an escherichia coli population under starvation stress conditions. | a novel system to study the evolution of transcription signals in heterologous systems under selective starvation conditions is described. it is based on the plasmid-mediated transfer of his biosynthetic genes from azospirillum brasilense into a heterologous escherichia coli mutant population lacking histidine biosynthetic ability. we show that under highly selective stressful conditions, genetic changes in the donor plasmid lead to mutated sequences that are efficiently recognized as promoters ... | 1998 | 9732463 |
| extracellular polysaccharides and polysaccharide-containing biopolymers from azospirillum species: properties and the possible role in interaction with plant roots. | this paper reviews the results obtained in studies of the extracellular polysaccharides, lipopolysaccharide-protein complexes, polysaccharide-lipid complexes, lipopolysaccharides, and o-specific polysaccharides from bacteria of the genus azospirillum. on the basis of present knowledge, the possible roles of the extracellular polysaccharides and polysaccharide-containing complexes of azospirilla in interaction with the roots of plants are discussed. some pieces of evidence are considered in light ... | 1998 | 9742692 |
| development of pcr primer systems for amplification of nitrite reductase genes (nirk and nirs) to detect denitrifying bacteria in environmental samples. | a system was developed for the detection of denitrifying bacteria by the amplification of specific nitrite reductase gene fragments with pcr. primer sequences were found for the amplification of fragments from both nitrite reductase genes (nirk and nirs) after comparative sequence analysis. whenever amplification was tried with these primers, the known nir type of denitrifying laboratory cultures could be confirmed. likewise, the method allowed a determination of the nir type of five laboratory ... | 1998 | 9758798 |
| bacterial chemotactic motility is important for the initiation of wheat root colonization by azospirillum brasilense. | bacteria of the genus azospirillum are able to colonize plant roots. using the beta-glucuronidase (gus) reporter system, various azospirillum mutants, including mutants affected in chemotactic motility or extracellular polysaccharide biosynthesis, were investigated for their capacity to initiate wheat root colonization at the root hair zones. only non-flagellated mutants and a generally non-chemotactic mutant exhibited a strongly reduced colonization ability as compared to the wild-type. no role ... | 1998 | 9782509 |
| a cytochrome cbb3 (cytochrome c) terminal oxidase in azospirillum brasilense sp7 supports microaerobic growth. | spectral analysis indicated the presence of a cytochrome cbb3 oxidase under microaerobic conditions in azospirillum brasilense sp7 cells. the corresponding genes (cytnoqp) were isolated by using pcr. these genes are organized in an operon, preceded by a putative anaerobox. the phenotype of an a. brasilense cytn mutant was analyzed. under aerobic conditions, the specific growth rate during exponential phase (mu(e)) of the a. brasilense cytn mutant was comparable to the wild-type specific growth r ... | 1998 | 9791120 |
| response of azospirillum brasilense cd to sodium chloride stress. | growth of azospirillum brasilense cd in the presence of different nacl concentrations showed that it tolerates up to 200 mm nacl in the medium, without appreciable decline in growth rate. at 300 mm nacl, a decrease of 66% in growth was observed at 24 h of culture. at 48 h of culture, bacteria in the presence of 300 mm nacl reached the maximum optical density value that was attained at 12 h by control cultures. this investigation was designed to elucidate the effect of saline stress on azospirill ... | 1998 | 9801770 |
| a pheromone-independent carr protein controls carbapenem antibiotic synthesis in the opportunistic human pathogen serratia marcescens. | strain atcc 39006 of serratia marcescens makes the same carbapenem, (5r)-carbapen-2-em-3-carboxylic acid (car), as the erwinia carotovora strain gs101. unlike e. carotovora, where the onset of production occurs in the late-exponential phase of growth in response to the accumulation of the small diffusible pheromone n-(3-oxohexanoyl)-l-homoserine lactone (ohhl), in s. marcescens carbapenem is produced throughout the growth phase and does not appear to involve any diffusible pheromone molecule. tw ... | 1998 | 9467912 |
| the recombinant alpha subunit of glutamate synthase: spectroscopic and catalytic properties. | as part of our studies of azospirillum brasilense glutamate synthase, a complex iron-sulfur flavoprotein, we have overproduced the two enzyme subunits separately in escherichia coli. the beta subunit (53.2 kda) was demonstrated to contain the site of nadph oxidation of glutamate synthase and the fad cofactor, which was identified as flavin 1 of glutamate synthase, the flavin located at the site of nadph oxidation. we now report the overproduction of the glutamate synthase alpha subunit (162 kda) ... | 1998 | 9485308 |
| a transcriptional regulator of the luxr-uhpa family, flca, controls flocculation and wheat root surface colonization by azospirillum brasilense sp7. | genetic complementation of a spontaneous mutant, impaired in flocculation, congo red binding, and colonization of root surface, led to the identification of a new regulatory gene in azospirillum brasilense sp7, designated flca. the deduced amino acid sequence of flca shared high similarity with a family of transcriptional activators of the luxr-upha family. the most significant match was with the agmr protein, an activator for glycerol metabolism in pseudomonas aeruginosa. derivatives of sp7 res ... | 1998 | 9487693 |
| nucleotide sequence of the nifh gene coding for nitrogen reductase in the acetic acid bacterium acetobacter diazotrophicus. | the nifh gene sequence of the nitrogen-fixing bacterium acetobacter diazotrophicus was determined with the use of the polymerase chain reaction and universal degenerate oligonucleotide primers. the gene shows highest pair-wise similarity to the nifh gene of azospirillum brasilense. the phylogenetic relationships of the nifh gene sequences were compared with those inferred from 16s rrna gene sequences. knowledge of the sequence of the nifh gene contributes to the growing database of nifh gene seq ... | 1998 | 9489028 |
| sequencing and complementation analysis of the nifusv genes from azospirillum brasilense. | the functionality of nitrogenase in diazotrophic bacteria is dependent upon nif genes other than the structural nifh, d, and k genes which encode the enzyme subunit proteins. such genes are involved in the activation of nif gene expression, maturation of subunit proteins, cofactor biosynthesis, and electron transport. in this work, approximately 5500 base pairs located within the major nif gene cluster of azospirillum brasilense sp7 have been sequenced. the deduced open reading frames were compa ... | 1998 | 9503607 |
| cell-surface lectins of azospirillum spp. | cell-surface lectins were screened in seven strains of azospirillum brasilense and a. lipoferum. the presence of lectins was determined by particle agglutination assays employing latex beads coated with neoglycoproteins and by western blot with neoglycoproteins labeled with horseradish peroxidase as a probe. seven strains were agglutinated with the assayed sugar residues. the highest agglutination was with fucose and glucose and to a lesser extent with mannose residues. cell-wall proteins extrac ... | 1998 | 9504993 |
| (methyl)ammonium transport in the nitrogen-fixing bacterium azospirillum brasilense. | an ammonium transporter of azospirillum brasilense was characterized. in contrast to most previously reported putative prokaryotic nh4+ transporter genes, a. brasilense amtb is not part of an operon with glnb or glnz which, in a. brasilense, encode nitrogen regulatory proteins pii and pz, respectively. sequence analysis predicts the presence of 12 transmembrane domains in the deduced amtb protein and classifies amtb as an integral membrane protein. nitrogen regulates the transcription of the amt ... | 1998 | 9573149 |
| identification and isolation of the indole-3-pyruvate decarboxylase gene from azospirillum brasilense sp7: sequencing and functional analysis of the gene locus. | the root-associated bacterium azospirillum brasilense sp7 produces the growth-stimulating phytohormone indole-3-acetic acid (= iaa) via the indole-3-pyruvate pathway. the dna region containing ipdc, the structural gene for indole-3-pyruvate decarboxylase, was identified in a cosmid gene library of strain sp7 by hybridization and has been sequenced. upstream of the gene, two other orf homologous to gltx and cyss were sequenced that are transcribed in the opposite direction. a functional analysis ... | 1998 | 9608743 |