| 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 |
| analysis of bacterial communities in the rhizosphere of chrysanthemum via denaturing gradient gel electrophoresis of pcr-amplified 16s rrna as well as dna fragments coding for 16s rrna. | the effect of developing chrysanthemum roots on the presence and activity of bacterial populations in the rhizosphere was examined by using culture-independent methods. nucleic acids were extracted from rhizosphere soil samples associated with the bases of roots or root tips of plants harvested at different stages of development. pcr and reverse transcriptase (rt) pcr were used to amplify 16s ribosomal dna (rdna) and 16s rrna, respectively, and the products were subjected to denaturing gradient ... | 2001 | 11133442 |
| 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 |
| effect of p(ii) and its homolog glnk on reversible adp-ribosylation of dinitrogenase reductase by heterologous expression of the rhodospirillum rubrum dinitrogenase reductase adp-ribosyl transferase-dinitrogenase reductase-activating glycohydrolase regulatory system in klebsiella pneumoniae. | reversible adp-ribosylation of dinitrogenase reductase, catalyzed by the dinitrogenase reductase adp-ribosyl transferase-dinitrogenase reductase-activating glycohydrolase (drat-drag) regulatory system, has been characterized in rhodospirillum rubrum and other nitrogen-fixing bacteria. to investigate the mechanisms for the regulation of drat and drag activities, we studied the heterologous expression of r. rubrum dratg in klebsiella pneumoniae glnb and glnk mutants. in k. pneumoniae wild type, th ... | 2001 | 11160092 |
| conserved gene cluster at replication origins of the alpha-proteobacteria caulobacter crescentus and rickettsia prowazekii. | a 30-kb region surrounding the replication origin in caulobacter crescentus was analyzed. comparison to the genome sequence of another alpha-proteobacterium, rickettsia prowazekii, revealed a conserved cluster of genes (rp001, heme, hemh, and rp883) that overlaps the established origin of replication in c. crescentus and the putative origin of replication in r. prowazekii. the genes flanking this cluster differ between these two organisms. we therefore propose that this conserved gene cluster ca ... | 2001 | 11160121 |
| an atp-binding cassette transporter and two rrna methyltransferases are involved in resistance to avilamycin in the producer organism streptomyces viridochromogenes tü57. | three different resistance factors from the avilamycin biosynthetic gene cluster of streptomyces viridochromogenes tü57, which confer avilamycin resistance when expressed in streptomyces lividans tk66, were isolated. analysis of the deduced amino acid sequences showed that aviabc1 is similar to a large family of atp-binding transporter proteins and that aviabc2 resembles hydrophobic transmembrane proteins known to act jointly with the atp-binding proteins. the deduced amino acid sequence of avir ... | 2001 | 11181344 |
| [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 |
| ammonia switch-off of nitrogen fixation in the methanogenic archaeon methanococcus maripaludis: mechanistic features and requirement for the novel glnb homologues, nifi(1) and nifi(2). | ammonia switch-off is the immediate inactivation of nitrogen fixation that occurs when a superior nitrogen source is encountered. in certain bacteria switch-off occurs by reversible covalent adp-ribosylation of the dinitrogenase reductase protein, nifh. ammonia switch-off occurs in diazotrophic species of the methanogenic archaea as well. we showed previously that in methanococcus maripaludis switch-off requires at least one of two novel homologues of glnb, a family of genes whose products play ... | 2001 | 11208785 |
| novel lysophospholipase a secreted by legionella pneumophila. | we show that legionella pneumophila possesses lysophospholipase a activity, which releases fatty acids from lysophosphatidylcholine. the nh2-terminal sequence of the enzyme contained fgdsls, corresponding to a catalytic domain in a recently described group of lipolytic enzymes. culture supernatants of a l. pneumophila pild mutant lost the ability to cleave lysophosphatidylcholine. | 2001 | 11222614 |
| bacterial populations colonizing and degrading rice straw in anoxic paddy soil. | rice straw is a major substrate for the production of methane, a greenhouse gas, in flooded rice fields. the bacterial community degrading rice straw under anoxic conditions was investigated with molecular methods. rice straw was incubated in paddy soil anaerobically for 71 days. denaturing gradient gel electrophoresis (dgge) of the amplified bacterial 16s rrna genes showed that the composition of the bacterial community changed during the first 15 days but then was stable until the end of incub ... | 2001 | 11229927 |
| 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 |
| p(ii) signal transduction proteins, pivotal players in microbial nitrogen control. | the p(ii) family of signal transduction proteins are among the most widely distributed signal proteins in the bacterial world. first identified in 1969 as a component of the glutamine synthetase regulatory apparatus, p(ii) proteins have since been recognized as playing a pivotal role in control of prokaryotic nitrogen metabolism. more recently, members of the family have been found in higher plants, where they also potentially play a role in nitrogen control. the p(ii) proteins can function in t ... | 2001 | 11238986 |
| [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 |
| 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 |
| rhesus factors and ammonium: a function in efflux? | completion of fungal, plant and human genomes paved the way to the identification of erythrocytic rhesus proteins and their kidney homologs as ammonium transporters. | 2001 | 11276430 |
| streptococcus salivarius fimbriae are composed of a glycoprotein containing a repeated motif assembled into a filamentous nondissociable structure. | streptococcus salivarius, a gram-positive bacterium found in the human oral cavity, expresses flexible peritrichous fimbriae. in this paper, we report purification and partial characterization of s. salivarius fimbriae. fimbriae were extracted by shearing the cell surface of hyperfimbriated mutant a37 (a spontaneous mutant of s. salivarius atcc 25975) with glass beads. preliminary experiments showed that s. salivarius fimbriae did not dissociate when they were incubated at 100 degrees c in the p ... | 2001 | 11292790 |
| 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 |
| 16s ribosomal dna characterization of nitrogen-fixing bacteria isolated from banana (musa spp.) and pineapple (ananas comosus (l.) merril). | nitrogen-fixing bacteria isolated from banana (musa spp.) and pineapple (ananas comosus (l.) merril) were characterized by amplified 16s ribosomal dna restriction analysis and 16s rrna sequence analysis. herbaspirillum seropedicae, herbaspirillum rubrisubalbicans, burkholderia brasilensis, and burkholderia tropicalis were identified. eight other types were placed in close proximity to these genera and other alpha and beta proteobacteria. | 2001 | 11319127 |
| 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 |
| effects of mutations in the pseudomonas putida miaa gene: regulation of the trpe and trpgdc operons in p. putida by attenuation. | tn5 insertion mutants defective in regulation of the pseudomonas putida trpe and trpgdc operons by tryptophan were found to contain insertions in the p. putida miaa gene, whose product (in escherichia coli) modifies trna(trp) and is required for attenuation. nucleotide sequences upstream of trpe and trpg encode putative leader peptides similar in sequence to leader peptides found in other bacterial species, and the phenotypes of the mutants strongly suggest that transcription of these operons is ... | 2001 | 11325956 |
| [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 |
| 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 |
| ralstonia solanacearum needs motility for invasive virulence on tomato. | ralstonia solanacearum, a widely distributed and economically important plant pathogen, invades the roots of diverse plant hosts from the soil and aggressively colonizes the xylem vessels, causing a lethal wilting known as bacterial wilt disease. by examining bacteria from the xylem vessels of infected plants, we found that r. solanacearum is essentially nonmotile in planta, although it can be highly motile in culture. to determine the role of pathogen motility in this disease, we cloned, charac ... | 2001 | 11371523 |
| genetic characterization and evolutionary implications of a car gene cluster in the carbazole degrader pseudomonas sp. strain ca10. | the nucleotide sequences of the 27,939-bp-long upstream and 9,448-bp-long downstream regions of the caraaaababbcac(orf7)ad genes of carbazole-degrading pseudomonas sp. strain ca10 were determined. thirty-two open reading frames (orfs) were identified, and the car gene cluster was consequently revealed to consist of 10 genes (caraaaababbcacaddfe) encoding the enzymes for the three-step conversion of carbazole to anthranilate and the degradation of 2-hydroxypenta-2,4-dienoate. the high identities ... | 2001 | 11371531 |
| role of a ferredoxin gene cotranscribed with the nifhdk operon in n(2) fixation and nitrogenase "switch-off" of azoarcus sp. strain bh72. | the endophytic diazotroph azoarcus sp. strain bh72 is capable of infecting rice roots and of expressing the nitrogenase (nif) genes there. in order to study the genetic background for nitrogen fixation in strain bh72, the structural genes of nitrogenase (nifhdk) were cloned and sequenced. the sequence analysis revealed an unusual gene organization: downstream of nifhdk, a ferredoxin gene (fdxn; 59% amino acid sequence identity to r. capsulatus fdxn) and open reading frames showing 52 and 36% ami ... | 2001 | 11371540 |
| changes in activity and community structure of methane-oxidizing bacteria over the growth period of rice. | the activity and community structure of methanotrophs in compartmented microcosms were investigated over the growth period of rice plants. in situ methane oxidation was important only during the vegetative growth phase of the plants and later became negligible. the in situ activity was not directly correlated with methanotrophic cell counts, which increased even after the decrease in in situ activity, possibly due to the presence of both vegetative cells and resting stages. by dividing the micro ... | 2001 | 11375143 |
| 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 |
| 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 |
| extracellular polysaccharides are involved in the attachment of azospirillum brasilense and rhizobium leguminosarum to arbuscular mycorrhizal structures. | arbuscular mycorrhizal (am) fungi, one of the most important component of the soil microbial community, establish physical interactions with naturally occurring and genetically modified bacterial biofertilizers and biopesticides, commonly referred to as plant growth-promoting rhizobacteria (pgpr). we have used a genetic approach to investigate the bacterial components possibly involved in the attachment of two pgpr (azospirillum and rhizobium) to am roots and am fungal structures. mutants affect ... | 2001 | 11411863 |
| isolation and characterization of a soluble nadph-dependent fe(iii) reductase from geobacter sulfurreducens. | nadph is an intermediate in the oxidation of organic compounds coupled to fe(iii) reduction in geobacter species, but fe(iii) reduction with nadph as the electron donor has not been studied in these organisms. crude extracts of geobacter sulfurreducens catalyzed the nadph-dependent reduction of fe(iii)-nitrilotriacetic acid (nta). the responsible enzyme, which was recovered in the soluble protein fraction, was purified to apparent homogeneity in a four-step procedure. its specific activity for f ... | 2001 | 11443080 |
| [participation of azospirillium polysaccharides in interaction with wheat root surface]. | the present study was undertaken to comparatively investigate the attachment capacities of azospirillum brasilense sp245 and its lipopolysaccharide-defective omegon-km mutants km018 and km252, as well as their activities with respect to the alteration of the morphology of wheat seedling root hairs. the adsorption dynamics of the parent sp245 and mutant km252 strains of azospirilla on the seedling roots of the soft spring wheat cv. saratovskaya 29 were similar; however, the attachment capacity of ... | 2001 | 11450462 |
| more than one way to sense chemicals. | | 2001 | 11466269 |
| genetic studies of mrp, a locus essential for cellular aggregation and sporulation of myxococcus xanthus. | under starvation conditions, myxococcus xanthus undergoes a complex developmental process which includes cellular aggregation and sporulation. a transposon insertion mutant (the tn5-omega280 mutant) with defects in both aggregation and sporulation was analyzed in this study. the tn5-omega280 mutant was found to have a disrupted ntrc-like response regulator designated myxococcus regulatory protein b (mrpb). further sequencing analyses revealed a histidine kinase homolog (mrpa) immediately upstrea ... | 2001 | 11466282 |
| potential roles for the glnb and ntryx genes in azospirillum brasilense. | three azospirillum brasilense mutants constitutive for nitrogen fixation (nif(c)) in the presence of nh4(+) and deficient in nitrate-dependent growth were used as tools to define the roles of the glnb and ntryx genes in this organism. mutant hm14 was complemented for nitrate-dependent growth and nh4(+) regulation of nitrogenase by plasmid pl46 which contains the ntryx genes of a. brasilense. mutant hm26 was restored for nh4(+) regulation and nitrate-dependent growth by plasmid pjc1, carrying the ... | 2001 | 11470362 |
| quantitative analysis of bacterial gene expression by using the gusa reporter gene system. | an azospirillum brasilense sp7 strain containing a plasmid-borne translational cytn-gusa fusion was grown in a continuous culture to quantitatively evaluate the influence of extracellular signals (such as o(2)) on expression of the cytnoqp operon. the dissolved oxygen concentration was shifted at regular time intervals before the steady state was reached. the measured beta-glucuronidase activity was used to monitor cytn gene expression. however, as the beta-glucuronidase activity in the experime ... | 2001 | 11472903 |
| expression of horizontally transferred gene clusters: activation by promoter-generating mutations. | the occurrence of promoter-generating mutations allowing the transcription of heterologous genes has been studied in a system based on the plasmid-mediated conjugal transfer of histidine biosynthetic genes from a donor bacterium (azospirillum brasilense) into a heterologous escherichia coli mutant population lacking histidine biosynthetic ability and initially unable to recognize the transcriptional signal of the introgressed gene(s). under selective stressful conditions, his+ revertants accumul ... | 2001 | 11501672 |
| the brucella suis homologue of the agrobacterium tumefaciens chromosomal virulence operon chve is essential for sugar utilization but not for survival in macrophages. | brucella strains possess an operon encoding type iv secretion machinery very similar to that coded by the agrobacterium tumefaciens virb operon. here we describe cloning of the brucella suis homologue of the chve-ggua-ggub operon of a. tumefaciens and characterize the sugar binding protein chve (78% identity), which in a. tumefaciens is involved in virulence gene expression. b. suis chve is upstream of the putative sugar transporter-encoding genes ggua and ggub, also present in a. tumefaciens, b ... | 2001 | 11514518 |
| sodium ion cycle in bacterial pathogens: evidence from cross-genome comparisons. | analysis of the bacterial genome sequences shows that many human and animal pathogens encode primary membrane na+ pumps, na+-transporting dicarboxylate decarboxylases or na+ translocating nadh:ubiquinone oxidoreductase, and a number of na+ -dependent permeases. this indicates that these bacteria can utilize na+ as a coupling ion instead of or in addition to the h+ cycle. this capability to use a na+ cycle might be an important virulence factor for such pathogens as vibrio cholerae, neisseria men ... | 2001 | 11528000 |
| polar flagellar motility of the vibrionaceae. | polar flagella of vibrio species can rotate at speeds as high as 100,000 rpm and effectively propel the bacteria in liquid as fast as 60 microm/s. the sodium motive force powers rotation of the filament, which acts as a propeller. the filament is complex, composed of multiple subunits, and sheathed by an extension of the cell outer membrane. the regulatory circuitry controlling expression of the polar flagellar genes of members of the vibrionaceae is different from the peritrichous system of ent ... | 2001 | 11528005 |
| effects of specific amino acid substitutions on activities of dinitrogenase reductase-activating glycohydrolase from rhodospirillum rubrum. | site-directed mutagenesis of the drag gene was used to generate altered forms of dinitrogenase reductase-activating glycohydrolase (drag) with d123a, h142l, h158n, d243g, and e279r substitutions. the amino acid residues h142 and e279 are not required either for the coordination to the metal center or for catalysis since the variants h142l and e279r retained both catalytic and electron paramagnetic resonance spectral properties similar to those of the wild-type enzyme. since drag-h158n and drag-d ... | 2001 | 11544238 |
| [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 |
| response of the endophytic diazotroph gluconacetobacter diazotrophicus on solid media to changes in atmospheric partial o(2) pressure. | gluconacetobacter diazotrophicus is an n(2)-fixing endophyte isolated from sugarcane. g. diazotrophicus was grown on solid medium at atmospheric partial o(2) pressures (po(2)) of 10, 20, and 30 kpa for 5 to 6 days. using a flowthrough gas exchange system, nitrogenase activity and respiration rate were then measured at a range of atmospheric po(2) (5 to 60 kpa). nitrogenase activity was measured by h(2) evolution in n(2)-o(2) and in ar-o(2), and respiration rate was measured by co(2) evolution in ... | 2001 | 11571174 |
| 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 |
| functional characterization of three glnb homologs in the photosynthetic bacterium rhodospirillum rubrum: roles in sensing ammonium and energy status. | the glnb (p(ii)) protein, the product of glnb, has been characterized previously in the photosynthetic bacterium rhodospirillum rubrum. here we describe identification of two other p(ii) homologs in this organism, glnk and glnj. although the sequences of these three homologs are very similar, the molecules have both distinct and overlapping functions in the cell. while glnb is required for activation of nifa activity in r. rubrum, glnk and glnj do not appear to be involved in this process. in co ... | 2001 | 11591658 |
| 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 |
| dna sequence and mutational analysis of rhizobitoxine biosynthesis genes in bradyrhizobium elkanii. | we cloned and sequenced a cluster of genes involved in the biosynthesis of rhizobitoxine, a nodulation enhancer produced by bradyrhizobium elkanii. the nucleotide sequence of the cloned 28.4-kb dna region encompassing rtxa showed that several open reading frames (orfs) were located downstream of rtxa. a large-deletion mutant of b. elkanii, usda94 delta rtx::omega 1, which lacks rtxa, orf1 (rtxc), orf2, and orf3, did not produce rhizobitoxine, dihydrorhizobitoxine, or serinol. the broad-host-rang ... | 2001 | 11679318 |
| expression of a pseudomonas putida aminotransferase involved in lysine catabolism is induced in the rhizosphere. | using a transposon carrying a promoterless lux operon to generate transcriptional fusions by insertional mutagenesis, we have identified a pseudomonas putida gene with increased expression in the presence of corn root exudates. expression of the transcriptional fusion, induced by the amino acid lysine, was detected in p. putida in the rhizosphere of plants as well as in response to seed exudates. the mutant was unable to grow on lysine or delta-aminovalerate as carbon sources, which indicates th ... | 2001 | 11679348 |
| 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 |
| the atp-dependent lon protease of salmonella enterica serovar typhimurium regulates invasion and expression of genes carried on salmonella pathogenicity island 1. | an early step in the pathogenesis of salmonella enterica serovar typhimurium infection is bacterial penetration of the intestinal epithelium. penetration requires the expression of invasion genes found in salmonella pathogenicity island 1 (spi1). these genes are controlled in a complex manner by regulators in spi1, including hila and invf, and those outside spi1, such as two-component regulatory systems and small dna-binding proteins. we report here that the expression of invasion genes and the ... | 2002 | 11741864 |
| [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 |
| cloning and characterisation of the azospirillum brasilense glnd gene and analysis of a glnd mutant. | nitrogen regulation in bacteria involves the capacity to sense the availability of fixed nitrogen and to translate a signal indicating nitrogen deficiency or nitrogen excess into a cellular response. one of the key enzymes in this complex regulation process, the uridylyltransferase/uridylyl-removing (utase) enzyme, encoded by the glnd gene, was characterised in the diazotroph azospirillum brasilense, which promotes plant growth. the glnd gene product is responsible for the uridylylation of both ... | 2002 | 11810255 |
| involvement of glnb, glnz, and glnd genes in the regulation of poly-3-hydroxybutyrate biosynthesis by ammonia in azospirillum brasilense sp7. | the role of three key nitrogen regulatory genes, glnb (encoding the p(ii) protein), glnz (encoding the p(z) protein), and glnd (encoding the glnd protein), in regulation of poly-3-hydroxybutyrate (phb) biosynthesis by ammonia in azospirillum brasilense sp7 was investigated. it was observed that glnb glnz and glnd mutants produce substantially higher amounts of phb than the wild type produces during the active growth phase. glnb and glnz mutants have phb production phenotypes similar to that of t ... | 2002 | 11823250 |
| 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 |
| membrane sequestration of the signal transduction protein glnk by the ammonium transporter amtb. | the amt proteins are ammonium transporters that are conserved throughout all domains of life, being found in bacteria, archaea and eukarya. in bacteria and archaea, the amt structural genes (amtb) are invariably linked to glnk, which encodes a member of the p(ii) signal transduction protein family, proteins that regulate enzyme activity and gene expression in response to the intracellular nitrogen status. we have now shown that in escherichia coli and azotobacter vinelandii, glnk binds to the me ... | 2002 | 11847102 |
| [characteristics of genes identified in the 120 mda plasmid dna in a mutant of azospirillum brasilense sp245 bacteria, defective in polar flagellation and swarming]. | the sequencing data were analyzed for two regions of the 120-mda plasmid (p120) of azospirillum brasilense sp245. the 2420-bp region i, which flanks the omegon insertion in the sk048 mutant defective in production of the polar flagellum (fla-) and swarming (swa-), was shown to contain a cluster of two open reading frames (orf) that possess properties of coding sequences (cdss). the ntra (sigma 54) boxes were found in their upstream regions. the products of orf1 and orf2 are 16.5 and 15.5 kda in ... | 2002 | 11852790 |
| [the use of fragments of the 85- and 120-mda plasmids of azospirillum brasilense sp245 to study the plasmid rearrangement in this bacterium and to search for homologous sequences in plasmids of azospirillum brasilense sp7]. | a spontaneous loss of the 85- (p85) and 120-mda (p120) replicons and simultaneous generation of a plasmid of more than 300 mda were associated with defects in synthesis of o-specific and calcofluor-binding polysaccharides and had no effect on flagellation and motility of the azospirillum brasilense sp245.5 mutant. the plasmid rearrangement was studied by hybridization of dnas from the wild-type sp245 strain and the sp245.5 mutant with p85 and p120 fragments that contained loci involved in format ... | 2002 | 11898609 |
| distinct roles of p(ii)-like signal transmitter proteins and amtb in regulation of nif gene expression, nitrogenase activity, and posttranslational modification of nifh in azoarcus sp. strain bh72. | p(ii)-like signal transmitter proteins, found in bacteria, archaea, and plants, are known to mediate control of carbon and nitrogen assimilation. they indirectly regulate the activity of key metabolic enzymes and transcription factors by protein-protein interactions with signal transduction proteins. many proteobacteria harbor two paralogous p(ii)-like proteins, glnb and glnk, whereas a novel third p(ii) paralogue (glny) was recently identified in azoarcus sp. strain bh72, a diazotrophic endophy ... | 2002 | 11914357 |
| towards growth of arbuscular mycorrhizal fungi independent of a plant host. | when surface-sterilized spores of the arbuscular mycorrhizal fungus (amf) glomus intraradices sy167 were germinated on agar plates in the slightly modified minimum mineral medium described by g. bécard and j. a. fortin (new phytol. 108:211-218, 1988), slime-forming bacteria, identified as paenibacillus validus, frequently grew up. these bacteria were able to support growth of the fungus on the agar plates. in the presence of p. validus, hyphae branched profusely and formed coiled structures. the ... | 2002 | 11916713 |
| inhibition of biosynthesis and activity of nitrogenase in azospirillum brasilense sp7 under salinity stress. | azospirillum brasilense is a microaerophilic, plant growth-promoting bacterium, whose nitrogenase activity has been shown to be sensitive to salinity stress. growth of a. brasilense in semi-solid medium showed that diazotrophic growth in n-free medium was relatively less sensitive to high nacl concentrations (200-400 mm) than that in presence of nh4+. increase in salinity stress to diazotrophic a. brasilense in the semi-solid medium led to the migration of the pellicle to deeper anaerobic zones. ... | 2002 | 11927988 |
| a major chemotaxis gene cluster in azospirillum brasilense and relationships between chemotaxis operons in alpha-proteobacteria. | azospirillum brasilense shows chemotaxis to a variety of nutrients and oxygen. genes encoding the central signal transduction pathway in chemotaxis were identified by phenotypic complementation of generally non-chemotactic mutants. sequencing of a dna fragment, which complemented two different mutants, revealed a region of five open reading frames translated in one direction and encoding homologs of known genes comprising excitation and adaptation pathways for chemotaxis in other bacterial speci ... | 2002 | 11934495 |
| trace cobalt speciation in bacteria and at enzymic active sites using emission mössbauer spectroscopy. | 57co emission mössbauer spectroscopy (ems) allows the chemical state of cobalt, as influenced by its coordination environment, to be monitored in biological samples at its physiological (trace) concentrations. to draw attention to ems as a valuable tool for speciation of cobalt in biocomplexes, the process of cobalt(ii) metabolism in cells of the plant growth-promoting rhizobacterium azospirillum brasilense sp245 was investigated using ems of 57coii-doped bacterial cells. ems measurements also s ... | 2002 | 11939529 |
| [effect of azospirillum brasilense lectin on the kinetics of lymph nodes cell populations and cytokine status in experimental animals]. | the complex study of the influence of a. brasilense sp 7 lectin with carbohydrate specificity to l-fucose and d-galactose on the dynamics of cell populations in different structural functional zones of the white mice mesentery, as well as on the capacity of immunocompetent cells of mesenterial lymph nodes for synthesizing cytokines (interleukin-1, interleukin-6 and tumor necrosis factor), was carried out. a single oral administration of bacterial lectin in a dose of 4.5 micrograms produced a pro ... | 2002 | 11949252 |
| structure of the o-specific polysaccharide of the lipopolysaccharide of azospirillum brasilense sp245. | an o-specific polysaccharide was isolated from the lipopolysaccharide of a plant-growth-promoting bacterium azospirillum brasilense sp245 and studied by sugar analyses along with one- and two-dimensional 1h and 13c nmr spectroscopy, including noesy. the polysaccharide was found to be a new rhamnan with a pentasaccharide repeating unit having the following structure:-->2)-beta-d-rhap-(1-->3)-alpha-d-rhap-(1-->3)-alpha-d-rhap-(1-->2)-alpha-d-rhap-(1-->2)-alpha-d-rhap-(1--> | 2002 | 11996841 |
| laccase activity in melanin-producing strains of sinorhizobium meliloti. | laccase-like activity was detected in melanin-producing strains of sinorhizobium meliloti mainly in cells at the stationary growth phase when copper was added to the medium. the laccase showed both syringaldazine and abts (2,2'-azino-bis-ethylbenzthiazoline-6-sulfonic acid) oxidase activities and was activated by the addition of 1.7 mm sodium dodecyl sulfate. activity was totally inhibited by the addition of 1.0 mm edta, suggesting that the enzyme is a metal-dependent one. the enzyme was found t ... | 2002 | 12007664 |
| [antigenic identity of the capsule lipopolysaccharides, exopolysaccharides, and o-specific polysaccharides in azospirillum brasilense]. | the antigenic identity (and close values of electrophoretic mobility) of capsular polysaccharides, exopolysaccharides, and o-specific polysaccharides was revealed in the azospirillum brasilense strains sp7 and sp245 by the immunodiffusion and immunoelectrophoretic methods. together with the literature data on the identity of the monosaccharides composition of these polymers, this gives evidence of the absence of a specific capsular antigen in the bacteria studied. thus, extracellular azospirillu ... | 2002 | 12024821 |
| 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 |
| protection of tomato seedlings against infection by pseudomonas syringae pv. tomato by using the plant growth-promoting bacterium azospirillum brasilense. | pseudomonas syringae pv. tomato, the causal agent of bacterial speck of tomato, and the plant growth-promoting bacterium azospirillum brasilense were inoculated onto tomato plants, either alone, as a mixed culture, or consecutively. the population dynamics in the rhizosphere and foliage, the development of bacterial speck disease, and their effects on plant growth were monitored. when inoculated onto separate plants, the a. brasilense population in the rhizosphere of tomato plants was 2 orders o ... | 2002 | 12039714 |
| identification and isolation of genes involved in poly(beta-hydroxybutyrate) biosynthesis in azospirillum brasilense and characterization of a phbc mutant. | like many other prokaryotes, rhizobacteria of the genus azospirillum produce high levels of poly(beta-hydroxybutyrate) (phb) under suboptimal growth conditions. utilization of phb by bacteria under stress has been proposed as a mechanism that favors their compatible establishment in competitive environments, thus showing great potential for the improvement of bacterial inoculants for plants and soils. the three genes that are considered to be essential in the phb biosynthetic pathway, phba (beta ... | 2002 | 12039753 |
| key role of bacterial nh(4)(+) metabolism in rhizobium-plant symbiosis. | symbiotic nitrogen fixation is carried out in specialized organs, the nodules, whose formation is induced on leguminous host plants by bacteria belonging to the family rhizobiaceae: nodule development is a complex multistep process, which requires continued interaction between the two partners and thus the exchange of different signals and metabolites. nh(4)(+) is not only the primary product but also the main regulator of the symbiosis: either as ammonium and after conversion into organic compo ... | 2002 | 12040124 |
| identification and characterization of the two-component ntry/ntrx regulatory system in azospirillum brasilense. | two azospirillum brasilense open reading frames (orfs) exhibited homology with the two-component ntry/ntrx regulatory system from azorhizobium caulinodans. these a. brasilense orfs, located downstream to the nifr3ntrbc operon, were isolated, sequenced and characterized. the present study suggests that orf1 and orf2 correspond to the a. brasilense ntry and ntrx genes, respectively. the amino acid sequences of a. brasilense ntry and ntrx proteins showed high similarity to sensor/kinase and regulat ... | 2002 | 12045829 |
| oviposition attractancy of bacterial culture filtrates: response of culex quinquefasciatus. | oviposition attractants could be used for monitoring as well as controlling mosquitoes by attracting them to lay eggs at chosen sites. in the present study, culture filtrates of seven bacterial species were tested for their attractancy against gravid females of culex quinquefasciatus. when their oviposition active indices (oai) were studied, the culture filtrates of bacillus cereus and pseudomonas fluorescens exhibited oviposition attractancy (oai = > 0.3) at 100 ppm and the oai were respectivel ... | 2002 | 12048566 |
| [changes in the antigenic properties of azospirillum brasilense lipopolysaccharide on addition of tris(hydroxymethyl)-aminomethane into the culture medium]. | addition of tris(hydroxymethyl)-aminomethane (tris) into the culture medium of azospirillum brasilense sp245 changes the antigenic properties of the lipopolysaccharide (lps) isolated from the external membrane of the bacteria. lps preparations from the bacteria grown in the presence of tris have been analyzed by immunodiffusion, using monospecific antibodies. the disappearance of the precipitation band corresponding to one of the two o-specific polysaccharides of the lps (o-ps1) and changes in t ... | 2002 | 12068582 |
| properties of the recombinant ferredoxin-dependent glutamate synthase of synechocystis pcc6803. comparison with the azospirillum brasilense nadph-dependent enzyme and its isolated alpha subunit. | the properties of the recombinant ferredoxin-dependent glutamate synthase of synechocystis pcc6803 were determined by means of kinetic and spectroscopic approaches in comparison to those exhibited by the bacterial nadph-dependent enzyme form. the ferredoxin-dependent enzyme was found to be similar to the bacterial glutamate synthase alpha subunit with respect to cofactor content (one fmn cofactor and one [3fe-4s] cluster per enzyme subunit), overall absorbance properties, and reactivity of the f ... | 2002 | 12069605 |
| monitoring azospirillum-wheat interactions using the gfp and gusa genes constitutively expressed from a new broad-host range vector. | to monitor the colonization of wheat roots by azospirillum brasilense, we constructed several plasmids based on the pbbr1 replicon expressing the gfp and gusa genes constitutively. both genes were placed under control of the gentamycin resistance gene promoter resulting in high levels of expression in escherichia coli and a. brasilense. the constructed plasmids were stably maintained in a. brasilense strains even in the absence of selective pressure. the colonization of wheat plants grown under ... | 2002 | 12084480 |
| amtb is necessary for nh(4)(+)-induced nitrogenase switch-off and adp-ribosylation in rhodobacter capsulatus. | rhodobacter capsulatus possesses two genes potentially coding for ammonia transporters, amtb and amty. in order to better understand their role in the physiology of this bacterium and their possible significance in nitrogen fixation, we created single-knockout mutants. strains mutated in either amtb or amty did not show a growth defect under any condition tested and were still capable of taking up ammonia at nearly wild-type rates, but an amtb mutant was no longer capable of transporting methyla ... | 2002 | 12107124 |
| expression of the nh(+)(4)-transporter gene leamt1;2 is induced in tomato roots upon association with n(2)-fixing bacteria. | plants growing in close association with n(2)-fixing bacteria are able to overcome growth limitations in n-depleted soils. the molecular mechanism by which free-living, n(2)-fixing bacteria promote plant growth is still a matter of debate. by inoculating n-depleted tomato (lycopersicon esculentum mill.) plants with azospirillum brasilense or azoarcus sp. we could demonstrate the induction of the root nh(+)(4)-transporter gene, leamt1;2 (l. esculentum ammonium transporter 1;2), indicating that ba ... | 2002 | 12111224 |
| degeneracy of antigen recognition as the molecular basis for the high frequency of naive a2/melan-a peptide multimer(+) cd8(+) t cells in humans. | in contrast with the low frequency of most single epitope reactive t cells in the preimmune repertoire, up to 1 of 1,000 naive cd8(+) t cells from a2(+) individuals specifically bind fluorescent a2/peptide multimers incorporating the a27l analogue of the immunodominant 26-35 peptide from the melanocyte differentiation and melanoma associated antigen melan-a. this represents the only naive antigen-specific t cell repertoire accessible to direct analysis in humans up to date. to get insight into t ... | 2002 | 12119345 |
| role of pseudomonas putida indoleacetic acid in development of the host plant root system. | many plant-associated bacteria synthesize the phytohormone indoleacetic acid (iaa). while iaa produced by phytopathogenic bacteria, mainly by the indoleacetamide pathway, has been implicated in the induction of plant tumors, it is not clear whether iaa synthesized by beneficial bacteria, usually via the indolepyruvic acid pathway, is involved in plant growth promotion. to determine whether bacterial iaa enhances root development in host plants, the ipdc gene that encodes indolepyruvate decarboxy ... | 2002 | 12147474 |
| biodiversity of denitrifying and dinitrogen-fixing bacteria in an acid forest soil. | isolated soil dna from an oak-hornbeam forest close to cologne, germany, was suitable for pcr amplification of gene segments coding for the 16s rrna and nitrogenase reductase (nifh), nitrous oxide reductase (nosz), cytochrome cd(1)-containing nitrite reductase (nirs), and cu-containing nitrite reductase (nirk) of denitrification. for each gene segment, diverse pcr products were characterized by cloning and sequencing. none of the 16s rrna gene sequences was identical to any deposited in the data ... | 2002 | 12147477 |
| increased pigment and lipid content, lipid variety, and cell and population size of the microalgae chlorella spp. when co-immobilized in alginate beads with the microalgae-growth-promoting bacterium azospirillum brasilense. | three strains of the freshwater microalgae used for wastewater treatment, chlorella vulgaris and chlorella sorokiniana co-immobilized separately in alginate beads with the microalgae-growth-promoting bacterium azospirillum brasilense cd, resulted in significant changes in microalgal-population size, cell size, cell cytology, pigment, lipid content, and the variety of fatty acids produced in comparison with microalgae immobilized in alginate without the bacterium. cells of c. vulgaris utex 2714 d ... | 2002 | 12166678 |
| removal of ammonium and phosphorus ions from synthetic wastewater by the microalgae chlorella vulgaris coimmobilized in alginate beads with the microalgae growth-promoting bacterium azospirillum brasilense. | coimmobilization of the freshwater microalga chlorella vulgaris in alginate beads with the microalgae growth-promoting bacterium azospirillum brasilense under semi-continuous synthetic wastewater culture conditions significantly increased the removal of ammonium and soluble phosphorus ions compared to immobilization of the microalgae alone. in continuous or batch cultures removal of these ions followed a similar trend but was less efficient than in semi-continuous culture. it is proposed that co ... | 2002 | 12171390 |
| sensitivity function-based model reduction: a bacterial gene expression case study. | mathematical models used to predict the behavior of genetically modified organisms require 1). a (rather) large number of state variables, and 2). complicated kinetic expressions containing a large number of parameters. since these models are hardly identifiable and of limited use in model-based optimization and control strategies, a generic methodology based on sensitivity function analysis is presented to reduce the model complexity at the level of the kinetics, while maintaining high predicti ... | 2002 | 12209775 |
| 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 |
| characterization of pigmented methylotrophic bacteria which nodulate lotononis bainesii. | root nodule isolates from a shrubby legume, lotononis bainesii, were characterized by 16s rrna gene sequencing and morphologically by substrate utilization patterns. the symbiotic genome of these isolates was analysed by partial sequencing of the nifh gene. based on the results of numerical taxonomy, the isolates formed a closely related cluster, showing no correspondence to any of the known rhizobial clusters. analysis of nearly full-length 16s rdna sequences demonstrated that these isolates we ... | 2002 | 12421082 |
| increased acidification in the rhizosphere of cactus seedlings induced by azospirillum brasilense. | acidification of the rhizosphere of cactus seedlings (giant cardon, pachycereus pringlei) after inoculation with the plant growth-promoting bacterium azospirillum brasilense cd, in the presence or absence of ammonium and nitrate, was studied to understand how to increase growth of cardon seedlings in poor desert soils. while ammonium enhanced rhizosphere and liquid culture acidification, inoculation with the bacteria enhanced it further. on the other hand, nitrate increased ph of the rhizosphere ... | 2002 | 12435098 |
| different evolutionary constraints on chemotaxis proteins chew and chey revealed by heterologous expression studies and protein sequence analysis. | chew and chey are single-domain proteins from a signal transduction pathway that transmits information from transmembrane receptors to flagellar motors in bacterial chemotaxis. in various bacterial and archaeal species, the chew and chey genes are usually encoded within homologous chemotaxis operons. we examined evolutionary changes in these two proteins from distantly related proteobacterial species, escherichia coli and azospirillum brasilense. we analyzed the functions of divergent chew and c ... | 2003 | 12511501 |
| [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 |
| characterization of the nodulation plasmid encoded chemoreceptor gene mcpg from rhizobium leguminosarum. | in general, chemotaxis in rhizobium has not been well characterized. methyl accepting chemotaxis proteins are sensory proteins important in chemotaxis of numerous bacteria, but their involvement in rhizobium chemotaxis is unclear and merits further investigation. | 2003 | 12553885 |
| effect of root exudates on the exopolysaccharide composition and the lipopolysaccharide profile of azospirillum brasilense cd under saline stress. | the effect of wheat root exudates on the exopolysaccharide (eps) composition and the lipopolysaccharide (lps) profile of azospirillum brasilense cd under saline stress was studied. eps of a. brasilense cd was composed of glucose (47%), mannose (3%), xylose (4%), fucose (28%), rhamnose (6%), arabinose (1%) and galactose (11%). under saline stress, a. brasilense produced a totally different eps, composed mainly of galactose. root exudates induced changes in a. brasilense eps composition only under ... | 2003 | 12594023 |
| lateral gene transfer and ancient paralogy of operons containing redundant copies of tryptophan-pathway genes in xylella species and in heterocystous cyanobacteria. | tryptophan-pathway genes that exist within an apparent operon-like organization were evaluated as examples of multi-genic genomic regions that contain phylogenetically incongruous genes and coexist with genes outside the operon that are congruous. a seven-gene cluster in xylella fastidiosa includes genes encoding the two subunits of anthranilate synthase, an aryl-coa synthetase, and trpr. a second gene block, present in the anabaena/nostoc lineage, but not in other cyanobacteria, contains a near ... | 2003 | 12620124 |