| fnr is involved in oxygen control of herbaspirillum seropedicae n-truncated nifa protein activity in escherichia coli. | herbaspirillum seropedicae is an endophytic diazotroph belonging to the beta-subclass of the class proteobacteria, which colonizes many members of the gramineae. the activity of the nifa protein, a transcriptional activator of nif genes in h. seropedicae, is controlled by ammonium ions through its n-terminal domain and by oxygen through mechanisms that are not well understood. here we report that the nifa protein of h. seropedicae is inactive and more susceptible to degradation in an fnr escheri ... | 2003 | 12620839 |
| paracoccus yeeii sp. nov. (formerly cdc group eo-2), a novel bacterial species associated with human infection. | cdc eugonic oxidizer group 2 (eo-2) is a group of unclassified gram-negative bacterial strains isolated from various human sources. as determined by biochemical tests and analyses of fatty acid compositions, these organisms form a homogeneous group that appears to be distinct from but related to other paracoccus species. molecular studies were performed on a set of 13 eo-2 strains from various clinical sources and geographic locations in the united states and canada to determine their relationsh ... | 2003 | 12624070 |
| identification of a third sulfate activation system in sinorhizobium sp. strain br816: the cysdn sulfate activation complex. | sinorhizobium sp. strain br816 possesses two nodpq copies, providing activated sulfate (3'-phosphoadenosine-5'-phosphosulfate [paps]) needed for the biosynthesis of sulfated nod factors. it was previously shown that the nod factors synthesized by a nodpq double mutant are not structurally different from those of the wild-type strain. in this study, we describe the characterization of a third sulfate activation locus. two open reading frames were fully characterized and displayed the highest simi ... | 2003 | 12676676 |
| [atypical r-s dissociation in azospirillum brasilense]. | it was found that atypical r-s dissociation in the type strain a. brasilense sp7 is not accompanied by drastic changes in the carbohydrate moieties of bacterial lipopolysaccharides but is rather due to different contributions of two o-specific polysaccharides (found in both r and s dissociants) to the age-dependent architectonics of the cell surface. | 2003 | 12698793 |
| characterization of the chlorate reductase from pseudomonas chloritidismutans. | a chlorate reductase has been purified from the chlorate-reducing strain pseudomonas chloritidismutans. comparison with the periplasmic (per)chlorate reductase of strain gr-1 showed that the cytoplasmic chlorate reductase of p. chloritidismutans reduced only chlorate and bromate. differences were also found in n-terminal sequences, molecular weight, and subunit composition. metal analysis and electron paramagnetic resonance measurements showed the presence of iron and molybdenum, which are also ... | 2003 | 12730181 |
| transformation of azospirillum brasilense cd with an acc deaminase gene from enterobacter cloacae uw4 fused to the tet r gene promoter improves its fitness and plant growth promoting ability. | it has been reported that pgpb, containing acc deaminase, can cleave the plant ethylene precursor acc and thereby lower ethylene concentration in a developing or stressed plant, protecting it against the deleterious effects of stress ethylene and facilitating the formation of longer roots. in a previous work we have demonstrated expression of the acc deaminase gene ( acds) from enterobacter cloacae uw4 under the control of the lac promoter in azospirillum brasilense cd. with the inference that a ... | 2003 | 12739073 |
| an azospirillum brasilense tn5 mutant with modified stress response and impaired in flocculation. | the analysis of an a. brasilense tn5 mutant shows significant phenotypic differences compared to the wild type isogenic strain. the transposon was located disrupting an open reading frame of 840 bp (orf280) which exhibits similarity to the universal stress protein (usp) family. the usp family encompasses proteins that are expressed as a response to cell growth arrest. the mutant revealed a pleiotrophic phenotype with respect to different stress conditions. the orf mutation results in an increase ... | 2003 | 12755478 |
| quaternary structure of azospirillum brasilense nadph-dependent glutamate synthase in solution as revealed by synchrotron radiation x-ray scattering. | azospirillum brasilense glutamate synthase (glts) is the prototype of bacterial nadph-dependent enzymes, a class of complex iron-sulfur flavoproteins essential in ammonia assimilation processes. the catalytically active glts alpha beta holoenzyme and its isolated alpha and beta subunits (162 and 52 kda, respectively) were analyzed using synchrotron radiation x-ray solution scattering. the glts alpha subunit and alpha beta holoenzyme were found to be tetrameric in solution, whereas the beta subun ... | 2003 | 12777402 |
| involvement of the reserve material poly-beta-hydroxybutyrate in azospirillum brasilense stress endurance and root colonization. | when grown under suboptimal conditions, rhizobacteria of the genus azospirillum produce high levels of poly-beta-hydroxybutyrate (phb). azospirillum brasilense strain sp7 and a phbc (phb synthase) mutant strain in which phb production is impaired were evaluated for metabolic versatility, for the ability to endure various stress conditions, for survival in soil inoculants, and for the potential to promote plant growth. the carbon source utilization data were similar for the wild-type and mutant s ... | 2003 | 12788722 |
| phylogeny and characterization of three nifh-homologous genes from paenibacillus azotofixans. | in this paper, we report the cloning and characterization of three paenibacillus azotofixans dna regions containing genes involved in nitrogen fixation. sequencing analysis revealed the presence of nifb1h1d1k1 gene organization in the 4,607-bp saci dna fragment. this is the first report of linkage of a nifb open reading frame upstream of the structural nif genes. the second (nifb2h2) and third (nifh3) nif homologues are confined within the 6,350-bp hindiii and 2,840-bp ecori dna fragments, respe ... | 2003 | 12788777 |
| regulation of glnb gene promoter expression in azospirillum brasilense by the ntrc protein. | in azospirillum brasilense the glnb and glna genes are clustered in an operon regulated by three different promoters: two located upstream of glnb (glnbp1-sigma(70), and glnbp2-sigma(n)) and one as yet unidentified promoter, in the glnba intergenic region. we have investigated the expression of the glnb gene promoter using glnb-lacz gene fusions, mutation analysis, heterologous expression and dna band-shift assays. deletion of the glnb promoter region showed that ntrc-binding sequences were esse ... | 2003 | 12798997 |
| gene function analysis in environmental isolates: the nif regulon of the strict iron oxidizing bacterium leptospirillum ferrooxidans. | a random genomic library from an environmental isolate of the gram-negative bacterium leptospirillum ferrooxidans has been printed on a microarray. gene expression analysis was carried out with total rna extracted from l. ferrooxidans cultures in the presence or absence of ammonium as nitrogen source under aerobic conditions. although practically nothing is known about the genome sequence of this bacterium, this approach allowed us the selection and sequencing of only those clones bearing genes ... | 2003 | 12808145 |
| wheat germ agglutinin is a growth factor for the bacterium azospirillum brasilense. | | 2003 | 12856415 |
| novel psychrophilic and thermolabile l-threonine dehydrogenase from psychrophilic cytophaga sp. strain kuc-1. | a psychrophilic bacterium, cytophaga sp. strain kuc-1, that abundantly produces a nad(+)-dependent l-threonine dehydrogenase was isolated from antarctic seawater, and the enzyme was purified. the molecular weight of the enzyme was estimated to be 139,000, and that of the subunit was determined to be 35,000. the enzyme is a homotetramer. atomic absorption analysis showed that the enzyme contains no metals. in these respects, the cytophaga enzyme is distinct from other l-threonine dehydrogenases t ... | 2003 | 12867457 |
| poly beta-hydroxybutyrate depolymerase (phaz) in azospirillum brasilense and characterization of a phaz mutant. | like many other prokaryotes, rhizobacteria of the genus azospirillum produce high levels of poly-beta-hydroxybutyrate (phb) under sub-optimal growth conditions. utilization of phb by bacteria under stress has been proposed as a mechanism that favors their compatible establishment in competitive environments. phb depolymerase (phaz) is an essential enzyme in phb degradation. the phaz gene was identified in azospirillum brasilense, cloned, sequenced, and shown to be located on the chromosome. inse ... | 2003 | 12898135 |
| [the bactericidal activity of lectins from nitrogen-fixing bacilli]. | lectins i and ii isolated from the nitrogen-fixing soil bacterium paenibacillus polymyxa 1460 were found to be able to suppress the growth of rhizobium leguminosarum 252 and bacillus subtilis 36 at nearly all the concentrations tested (from 1 to 10 micrograms/ml). lectin i was also inhibitory to azospirillum brasilense 245 and erwinia carotovora subsp. citrulis 603, while lectin ii exerted bactericidal activity against xanthomonas campestris b-610 and b-611 and a. brasilense 245. the bacillar le ... | 2003 | 12901008 |
| yeast two-hybrid studies on interaction of proteins involved in regulation of nitrogen fixation in the phototrophic bacterium rhodobacter capsulatus. | rhodobacter capsulatus contains two pii-like proteins, glnb and glnk, which play central roles in controlling the synthesis and activity of nitrogenase in response to ammonium availability. here we used the yeast two-hybrid system to probe interactions between these pii-like proteins and proteins known to be involved in regulating nitrogen fixation. analysis of defined protein pairs demonstrated the following interactions: glnb-ntrb, glnb-nifa1, glnb-nifa2, glnb-drat, glnk-nifa1, glnk-nifa2, and ... | 2003 | 12923097 |
| [effect of cultivation parameters on the composition of extracellular polysaccharide containing substances in bacterium azospirillum brasilense]. | maintenance of ph 7.0 during the fermentation period favors accumulation of high-molecular polysaccharide-containing components, the so-called lipopolysaccharide-protein and polysaccharide-lipid complexes, in the capsules and culture medium. increased ph of the culture medium to 8.0 reduced the period of exponential growth and the yield of polysaccharide-containing complexes as compared to the optimal conditions. maintenance of ph 5.5 suppressed the culture growth and polysaccharide production. ... | 2003 | 12942749 |
| phenotypic changes resulting from distinct point mutations in the azospirillum brasilense glna gene, encoding glutamine synthetase. | sequencing the glna genes of two chemically induced azospirillum brasilense glutamine synthetase mutants revealed an arg-->cys mutation, corresponding to the glutamate binding site, in one mutant and an asp-->asn mutation, corresponding to the ammonium binding site, in the second mutant. the phenotypic changes in these mutants are discussed in relation to their genotypes. | 2003 | 12957965 |
| identification of three genes encoding p(ii)-like proteins in gluconacetobacter diazotrophicus: studies of their role(s) in the control of nitrogen fixation. | in our studies on the regulation of nitrogen metabolism in gluconacetobacter diazotrophicus, an endophytic diazotroph of sugarcane, three glnb-like genes were identified and their role(s) in the control of nitrogen fixation was studied. sequence analysis revealed that one p(ii) protein-encoding gene, glnb, was adjacent to a glna gene (encoding glutamine synthetase) and that two other p(ii) protein-encoding genes, identified as glnk1 and glnk2, were located upstream of amtb1 and amtb2, respective ... | 2003 | 13129958 |
| synthesis and biological evaluation of new amino acids structurally related to the antitumor agent acivicin. | a set of racemic conformationally constrained analogues of the antitumor antibiotic acivicin (+)-1 has been prepared through a strategy based on 1,3-dipolar cycloaddition of bromonitrile oxide to suitable dipolarophiles. the bromo analogue (2) of acivicin was also synthesized and tested as a reference compound, together with its stereoisomer 3. the antitumor properties of novel amino acids 4-7 were evaluated in vitro against human tumor cell lines. their efficacy to inhibit glutamate synthase (g ... | 2003 | 13679161 |
| indole-3-butyric acid (iba) production in culture medium by wild strain azospirillum brasilense. | some microorganisms found in the soil are able to produce substances which regulate plant growth. in this study, we show the presence of a substance associated with auxin activity, identified as indole-3-butyric acid (iba), in azospirillum brasilense uap 154 growth medium. a. brasilense was grown and indolic compounds were extracted from the supernatant. these were then analyzed by high performance liquid chromatography (hplc), gas chromatography and gas chromatography mass spectrometry. the ret ... | 2003 | 14638420 |
| model of bacterial band formation in aerotaxis. | aerotaxis is a particular form of "energy taxis". it is based on a largely elusive signal transduction machinery. in aerotaxis, oxygen dissolved in water plays the role of both attractant (at moderate concentrations) and repellent (at high and low concentrations). cells swimming from favorable oxygen concentrations into regions with unfavorable concentrations increase the frequency of reversals, turn back into the favorable domain, and become effectively trapped there. at the same time, bacteria ... | 2003 | 14645050 |
| microalgae growth-promoting bacteria as "helpers" for microalgae: a novel approach for removing ammonium and phosphorus from municipal wastewater. | a combination of microalgae (chlorella vulgaris or c. sorokiniana) and a microalgae growth-promoting bacterium (mgpb, azospirillum brasilense strain cd), co-immobilized in small alginate beads, was developed to remove nutrients (p and n) from municipal wastewater. this paper describes the most recent technical details necessary for successful co-immobilization of the two microorganisms, and the usefulness of the approach in cleaning the municipal wastewater of the city of la paz, mexico. a. bras ... | 2004 | 14675659 |
| in vitro uridylylation of the azospirillum brasilense n-signal transducing glnz protein. | azospirillum brasilense is a diazotroph which associates with important agricultural crops. the nitrogen fixation process in this organism is highly regulated by ammonium and oxygen, and involves several proteins including the two pii-like proteins, glnb and glnz. although these proteins are structurally very similar, they play different roles in the control of nitrogen fixation. in this work, we describe the expression, purification, and uridylylation of the glnz protein of a. brasilense strain ... | 2004 | 14680957 |
| identification of critical residues in glnb for its activation of nifa activity in the photosynthetic bacterium rhodospirillum rubrum. | the p(ii) regulatory protein family is unusually widely distributed, being found in all three domains of life. three p(ii) homologs called glnb, glnk, and glnj have been identified in the photosynthetic bacterium rhodospirillum rubrum. these have roles in at least four distinct functions, one of which is activation of the nitrogen fixation-specific regulatory protein nifa. the activation of nifa requires only the covalently modified (uridylylated) form of glnb. glnk and glnj are not involved. ho ... | 2004 | 14970346 |
| a method for studying insoluble immune complexes. | two variants of a method for determining the average composition of insoluble immune complex particles (iicp) are described. the first variant is based on measuring the specific turbidity (the turbidity per unit mass concentration of the dispersed substance) and the average size of iicp determined from dynamic light scattering (dls). in the second variant, the slope of the logarithmic turbidity spectrum (wavelength exponent) is used instead of dls particle size. both variants allow the average b ... | 2004 | 14980446 |
| disruption of dtdp-rhamnose biosynthesis modifies lipopolysaccharide core, exopolysaccharide production, and root colonization in azospirillum brasilense. | the interaction between azospirillum brasilense and plants is not fully understood, although several bacterial surface components like exopolysaccharides (eps), flagella, and capsular polysaccharides are required for attachment and colonization. while in other plant-bacteria associations (rhizobium-legume, pseudomonas-potato), lipopolysaccharides (lps) play a key role in the establishment of an effective association, their role in the root colonization by azospirillum had not been determined. in ... | 2004 | 14987774 |
| the fixabcx genes in rhodospirillum rubrum encode a putative membrane complex participating in electron transfer to nitrogenase. | in our efforts to identify the components participating in electron transport to nitrogenase in rhodospirillum rubrum, we used mini-tn5 mutagenesis followed by metronidazole selection. one of the mutants isolated, snt-1, exhibited a decreased growth rate and about 25% of the in vivo nitrogenase activity compared to the wild-type values. the in vitro nitrogenase activity was essentially wild type, indicating that the mutation affects electron transport to nitrogenase. sequencing showed that the t ... | 2004 | 15028689 |
| annotation of the prhico plasmid of azospirillum brasilense reveals its role in determining the outer surface composition. | the plant growth-promoting soil bacterium azospirillum brasilense enhances growth of economically important crops, such as wheat, corn and rice. in order to improve plant growth, a close bacterial association with the plant roots is needed. genes encoded on a 90-mda plasmid, denoted prhico plasmid, present in a. brasilense sp7, play an important role in plant root interaction. sequencing, annotation and in silico analysis of this 90-mda plasmid revealed the presence of a large collection of gene ... | 2004 | 15033235 |
| the spatial orientation of helicobacter pylori in the gastric mucus. | the highly motile human pathogen helicobacter pylori lives deep in the gastric mucus layer. to identify which chemical gradient guides the bacteria within the mucus layer, combinations of luminal perfusion, dialysis, and ventilation were used to modify or invert transmucus gradients in anaesthetized helicobacter-infected mice and mongolian gerbils. neither changes in lumen or arterial ph nor inversion of bicarbonate/co2 or urea/ammonium gradients disturbed helicobacter orientation. however, elim ... | 2004 | 15044704 |
| 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 |
| ultrastructure of interaction in alginate beads between the microalga chlorella vulgaris with its natural associative bacterium phyllobacterium myrsinacearum and with the plant growth-promoting bacterium azospirillum brasilense. | chlorella vulgaris, a microalga often used in wastewater treatment, was coimmobilized and coincubated either with the plant growth-promoting bacterium azospirillum brasilense, or with its natural associative bacterium phyllobacterium myrsinacearum, in alginate beads designed for advanced wastewater treatment. interactions between the microalga and each of the bacterial species were followed using transmission electron microscopy for 10 days. initially, most of the small cavities within the beads ... | 2001 | 15049443 |
| metalloregulation of yeast membrane steroid receptor homologs. | zinc is an essential micronutrient that can also be toxic. an intricate mechanism exists in yeast that maintains cellular zinc within an optimal range. the centerpiece of this mechanism is the zap1p protein, a transcription factor that senses zinc deficiency and responds by up-regulating genes involved in zinc metabolism. a microarray screen for novel zap1p target genes suggested a role in zinc homeostasis for four homologous yeast genes. the expression of two of these genes, ydr492w and yol002c ... | 2004 | 15060275 |
| genetic evidence that the vibrio cholerae monolayer is a distinct stage in biofilm development. | biofilm development is conceived as a developmental process in which free swimming cells attach to a surface, first transiently and then permanently, as a single layer. this monolayer of immobilized cells gives rise to larger cell clusters that eventually develop into the biofilm, a three-dimensional structure consisting of large pillars of bacteria interspersed with water channels. previous studies have shown that efficient development of the vibrio cholerae biofilm requires a combination of pi ... | 2004 | 15066042 |
| electrooptical analysis of the escherichia coli-phage interaction. | this article describes electrooptical (eo) characterization of biospecific binding between the bacterium escherichia coli xl-1 and the phage m13k07. the electrooptical analyzer (elus eo), which has been developed at the state research center for applied microbiology, obolensk, russia, was used as the basic instrument for eo measurements. the operating principle of the analyzer is based on the polarizability of microorganisms, which depends strongly on their composition, morphology, and phenotype ... | 2004 | 15113695 |
| structural characterization of glutamine synthetase from azospirillum brasilense. | cd spectroscopic study of the secondary structure of partly adenylylated glutamine synthetase (gs) of the bacterium azospirillum brasilense showed both the native and cation-free (edta-treated) enzyme to be highly structured (58 and 49% as alpha-helices, 10 and 20% as beta-structure, respectively). mg(2+), mn(2+), or co(2+), when added to the native gs, had little effect on its cd spectrum, whereas their effects on the cation-free gs were more pronounced. emission ((57)co) mössbauer spectroscopi ... | 2004 | 15137096 |
| studies of listeria monocytogenes-antibody binding using electro-orientation. | an electro-optical (eo) approach has been used for studies of listeria monocytogenes-antibody binding. the eo analyzer, which has been developed at the state research center for applied microbiology, obolensk, was used as a basic instrument for eo measurements. ac electro-kinetic effects depend on dielectric properties of bioparticles, their composition, morphology, the medium, and the frequency of applied electrical field. electro-orientational spectra were used for discrimination of bacteria b ... | 2004 | 15142611 |
| diversity in chemotaxis mechanisms among the bacteria and archaea. | the study of chemotaxis describes the cellular processes that control the movement of organisms toward favorable environments. in bacteria and archaea, motility is controlled by a two-component system involving a histidine kinase that senses the environment and a response regulator, a very common type of signal transduction in prokaryotes. most insights into the processes involved have come from studies of escherichia coli over the last three decades. however, in the last 10 years, with the sequ ... | 2004 | 15187186 |
| [a comparison of the lipopolysaccharides and o-specific polysaccharides of azospirillum brasilense sp245 and its omegon-km mutants km018 and km252]. | the lipopolysaccharides (lpss) extracted from the outer membrane of azospirillum brasilense sp245 and its omegon-km mutants km018 and km252 with a hot aqueous solution of phenol were found to differ in the content of carbohydrates, glucosamine, and total phosphorus and in the proportion of octadecenoic and hexadecanoic acids in the lipid moieties of the lpss. the carbohydrate moieties of the lpss were heterogeneous in charge. the analysis of the o-specific polysaccharides (o-pss) of the mutants ... | 2004 | 15198028 |
| anaplasma phagocytophilum has a functional msp2 gene that is distinct from p44. | the msp2 and p44 genes encode polymorphic major outer membrane proteins that are considered unique to the intraerythrocytic agent of anaplasma marginale and the intragranulocytic agent of anaplasma phagocytophilum, respectively. in the present study, however, we found an msp2 gene in a. phagocytophilum that was remarkably conserved among a. phagocytophilum strains from human granulocytic anaplasmosis (hga) patients, ticks, and a horse from various regions in the united states, but the gene was d ... | 2004 | 15213131 |
| contribution of gene loss to the pathogenic evolution of burkholderia pseudomallei and burkholderia mallei. | burkholderia pseudomallei is the causative agent of melioidosis. burkholderia thailandensis is a closely related species that can readily utilize l-arabinose as a sole carbon source, whereas b. pseudomallei cannot. we used tn5-ot182 mutagenesis to isolate an arabinose-negative mutant of b. thailandensis. sequence analysis of regions flanking the transposon insertion revealed the presence of an arabinose assimilation operon consisting of nine genes. analysis of the b. pseudomallei chromosome show ... | 2004 | 15213162 |
| molecular and physiological comparison of azospirillum spp. isolated from rhizoctonia solani mycelia, wheat rhizosphere, and human skin wounds. | four phenotypically similar bacterial strains isolated from fungal, plant, and human sources were identified as azospirillum species. strains rc1 and lod4 were isolated from the mycelium of the apple root pathogen rhizoctonia solani ag 5 and from the rhizosphere of wheat grown in apple orchard soil, respectively. strains c610 and f4626 isolated from human wounds were previously misclassified as roseomonas genomospecies 3 and 6. all four strains demonstrated close similarities in 16s rrna gene se ... | 2004 | 15213753 |
| evaluation of fly ash as a carrier for diazotrophs and phosphobacteria. | fly ash and its different combinations with soil (w/w) were tested to explore its possible use as a potential carrier for diazotrophs and phosphobacteria. azotobacter chroococcum, azospirillum brasilense and bacillus circulans showed their maximum viability in fly ash alone whereas pseudomonas striata proliferated most in soil:fly ash (1:1) combination. | 2004 | 15246443 |
| effects of plant growth promoting bacteria and composed organic fertilizers on the reproduction of meloidogyne incognita and tomato growth. | glasshouse experiments were conducted to assess the influence of pseudomonas fluorescens, azotobacter chroococcum, azospirillum brasilense and composted organic fertilizers (cow dung, horse dung, goat dung and poultry manure) alone and in combination on the multiplication of meloidogyne incognita and growth of tomato. p. fluorescens was better at improving tomato growth and reducing galling and nematode multiplication than a. chroococcum or a. brasilense. among composted organic fertilizers, pou ... | 2004 | 15246448 |
| glnb is specifically required for azospirillum brasilense nifa activity in escherichia coli. | the azospirillum brasilense transcription regulator nifa and the nitrogen-status signaling proteins glnb, glnz and glnk were expressed in escherichia coli and analyzed for their ability to activate nif gene expression. when expressed separately, none of the proteins were able to activate nifh promoter expression in any tested conditions; in contrast, nifh expression was observed in cells grown in the absence of ammonium and oxygen and when expressing simultaneously nifa and glnb proteins, but no ... | 2004 | 15249067 |
| extended phenotype of an mreb-like mutant in azospirillum brasilense. | tn5 mutagenesis was used to generate an azospirillum brasilense spf94 mutant. genetic analysis of this mutant revealed that a homologue of the mreb gene, which controls cell shape in bacillus subtilis and escherichia coli, was inactivated. the cell-surface properties of the mutant were different from those of the parental strain. the mutant colonies were highly fluorescent when grown on plates containing calcofluor white. light and electron microscopy revealed that the mutant cells were round an ... | 2004 | 15256588 |
| monitoring of cobalt(ii) uptake and transformation in cells of the plant-associated soil bacterium azospirillum brasilense using emission mössbauer spectroscopy. | interaction of cobalt(ii) at micromolar concentrations with live cells of the plant-growth-promoting rhizobacterium azospirillum brasilense (strain sp245) and further transformations of the metal cation were monitored using 57co emission mössbauer spectroscopy (ems). cell suspensions of the bacterial culture (2.4 x 10(8) cells ml(-1)) were doped with radioactive 57cocl2 (1 mci; final concentration 2 x 10(-6) m 57co2+), kept under physiological conditions for various periods of time (from 2 min u ... | 2004 | 15259367 |
| hypercyst mutants in rhodospirillum centenum identify regulatory loci involved in cyst cell differentiation. | rhodospirillum centenum is a purple photosynthetic bacterium that forms resting cyst cells when starved for nutrients. in this study, we demonstrate that chalcone synthase gene (chsa) expression is developmentally regulated, with expression of chsa increasing up to 86-fold upon induction of the cyst developmental cycle. screening for mini-tn5-induced mutants that exhibit elevated chsa::lacz expression has led to the isolation of a set of r. centenum mutants that display increased chsa gene expre ... | 2004 | 15317789 |
| arabinose content of extracellular polysaccharide plays a role in cell aggregation of azospirillum brasilense. | extracellular polysaccharides play an important role in aggregation and surface colonization of plant-associated bacteria. in this work, we report the time course production and monomer composition of the exopolysaccharide (eps) produced by wild type strain and several mutants of the plant growth promoting rhizobacterium (pgpr) azospirillum brasilense. in a fructose synthetic medium, wild type strain sp7 produced a glucose-rich eps during exponential phase growth and an arabinose-rich eps during ... | 2004 | 15321662 |
| [single insertions of omegon into azospirillum brasilense dna result in defects in the bacterial mobility of several types]. | | 2004 | 15354940 |
| an energy taxis transducer promotes root colonization by azospirillum brasilense. | motility responses triggered by changes in the electron transport system are collectively known as energy taxis. in azospirillum brasilense, energy taxis was shown to be the principal form of locomotor control. in the present study, we have identified a novel chemoreceptor-like protein, named tlp1, which serves as an energy taxis transducer. the tlp1 protein is predicted to have an n-terminal periplasmic region and a cytoplasmic c-terminal signaling module homologous to those of other chemorecep ... | 2004 | 15375141 |
| transfer of a plant chitinase gene into a nitrogen-fixing azospirillum and study of its expression. | azospirillum is used extensively in rice and other cereal crops as a biofertilizer. there is a substantial opportunity to improve the efficiency of this bacterium through the transfer of genes of agricultural importance from other organisms. chitinases are antifungal proteins, and expression of chitinase genes in azospirillum would help to develop strains with potential antifungal activities. so far there are no reports about transfer of plant genes into azospirillum and their expression. the pr ... | 2004 | 15381976 |
| the electron transfer flavoprotein fixabcx gene products from azospirillum brasilense show a nifa-dependent promoter regulation. | the complete nucleotide sequence of the a. brasilense fixa, fixb, fixc, and fixx genes is reported here. sequence similarities between the protein sequences deduced from fixabcx genes and many electron transfer flavoproteins (etfs) have been noted. comparison of the amino acid sequences of both subunits of etf with the a. brasilense fixa and fixb gene products exhibits an identity of 30%. the amino acid sequence of the other two genes, fixc and fixx, revealed similarity with the membrane-bound e ... | 2004 | 15386115 |
| flagellin from listeria monocytogenes is glycosylated with beta-o-linked n-acetylglucosamine. | glycan staining of purified flagellin from listeria monocytogenes serotypes 1/2a, 1/2b, 1/2c, and 4b suggested that the flagellin protein from this organism is glycosylated. mass spectrometry analysis demonstrated that the flagellin protein of l. monocytogenes is posttranslationally modified with o-linked n-acetylglucosamine (glcnac) at up to six sites/monomer. the sites of glycosylation are all located in the central, surface-exposed region of the protein monomer. immunoblotting with a monoclon ... | 2004 | 15466023 |
| repressor mutant forms of the azospirillum brasilense ntrc protein. | the azospirillum brasilense mutant strains fp8 and fp9, after treatment with nitrosoguanidine, showed a null nif phenotype and were unable to use nitrate as their sole nitrogen source. sequencing of the ntrc genes revealed single nucleotide mutations in the ntrc nucleotide-binding site. the phenotypes of these strains are discussed in relation to their genotypes. | 2004 | 15466584 |
| molecular dynamics simulation of the interaction between the complex iron-sulfur flavoprotein glutamate synthase and its substrates. | glutamate synthase (glts) is a complex iron-sulfur flavoprotein that catalyzes the reductive transfer of l-glutamine amide group to the c2 carbon of 2-oxoglutarate yielding two molecules of l-glutamate. molecular dynamics calculations in explicit solvent were carried out to gain insight into the conformational flexibility of glts and into the role played by the enzyme substrates in regulating the catalytic cycle. we have modelled the free (unliganded) form of azospirillum brasilense glts alpha s ... | 2004 | 15498940 |
| diversity of green-like and red-like ribulose-1,5-bisphosphate carboxylase/oxygenase large-subunit genes (cbbl) in differently managed agricultural soils. | a pcr-based approach was developed to detect ribulose-1,5-bisphosphate carboxylase/oxygenase (rubisco) form i large-subunit genes (cbbl) as a functional marker of autotrophic bacteria that fix carbon dioxide via the calvin-benson-bassham cycle. we constructed two different primer sets, targeting the green-like and red-like phylogenetic groups of cbbl genes. the diversity of these cbbl genes was analyzed by the use of three differently managed agricultural soils from a long-term field experiment. ... | 2005 | 15640185 |
| influence of substrate composition and flow rate on growth of azospirillum brasilense cd in a co-culture with 3 sorghum rhizobacteria. | the ability of azospirillum brasilense cd to colonize the niche occupied by 3 bacterial strains previously isolated from sorghum rhizosphere was studied by means of the biolog system. the isolates were identified by different methods as strains belonging to pseudomonas putida, stenotrophomonas maltophilia, and klebsiella terrigena species. several c sources, also chosen among the constituents of sorghum root exudates, were used to evaluate the metabolic profiles of azospirillum and the sorghum r ... | 2004 | 15644901 |
| glnd is essential for nifa activation, ntrb/ntrc-regulated gene expression, and posttranslational regulation of nitrogenase activity in the photosynthetic, nitrogen-fixing bacterium rhodospirillum rubrum. | glnd is a bifunctional uridylyltransferase/uridylyl-removing enzyme and is thought to be the primary sensor of nitrogen status in the cell. it plays an important role in nitrogen assimilation and metabolism by reversibly regulating the modification of p(ii) proteins, which in turn regulate a variety of other proteins. we report here the characterization of glnd mutants from the photosynthetic, nitrogen-fixing bacterium rhodospirillum rubrum and the analysis of the roles of glnd in the regulation ... | 2005 | 15687189 |
| [a comparative study of the effect of the lectins of azospirillum brasilense sp7 and its mutant on the activity of some enzymes in plant cells]. | | 2004 | 15688946 |
| effects of over-expression of the regulatory enzymes drat and drag on the ammonium-dependent post-translational regulation of nitrogenase reductase in azospirillum brasilense. | nitrogen fixation in azospirillum brasilense is regulated at transcriptional and post-translational levels. post-translational control occurs through the reversible adp-ribosylation of dinitrogenase reductase (fe protein), mediated by the dinitrogenase reductase adp-ribosyltransferase (drat) and dinitrogenase reductase glycohydrolase (drag). although the drat and drag activities are regulated in vivo, the molecules responsible for such regulation remain unknown. we have constructed broad-host-ra ... | 2005 | 15723223 |
| biosynthesis of auxin by the gram-positive phytopathogen rhodococcus fascians is controlled by compounds specific to infected plant tissues. | the role and metabolism of indole-3-acetic acid in gram-negative bacteria is well documented, but little is known about indole-3-acetic acid biosynthesis and regulation in gram-positive bacteria. the phytopathogen rhodococcus fascians, a gram-positive organism, incites diverse developmental alterations, such as leafy galls, on a wide range of plants. phenotypic analysis of a leafy gall suggests that auxin may play an important role in the development of the symptoms. we show here for the first t ... | 2005 | 15746315 |
| detection of and response to signals involved in host-microbe interactions by plant-associated bacteria. | diverse interactions between hosts and microbes are initiated by the detection of host-released chemical signals. detection of these signals leads to altered patterns of gene expression that culminate in specific and adaptive changes in bacterial physiology that are required for these associations. this concept was first demonstrated for the members of the family rhizobiaceae and was later found to apply to many other plant-associated bacteria as well as to microbes that colonize human and anima ... | 2005 | 15755957 |
| transcriptome analysis of shewanella oneidensis mr-1 in response to elevated salt conditions. | whole-genomic expression patterns were examined in shewanella oneidensis cells exposed to elevated sodium chloride. genes involved in na(+) extrusion and glutamate biosynthesis were significantly up-regulated, and the majority of chemotaxis/motility-related genes were significantly down-regulated. the data also suggested an important role for metabolic adjustment in salt stress adaptation in s. oneidensis. | 2005 | 15774893 |
| the unexpected structural role of glutamate synthase [4fe-4s](+1,+2) clusters as demonstrated by site-directed mutagenesis of conserved c residues at the n-terminus of the enzyme beta subunit. | azospirillum brasilense glutamate synthase (glts) is a complex iron-sulfur flavoprotein whose catalytically active alphabeta protomer (alpha subunit, 162kda; beta subunit, 52.3 kda) contains one fad, one fmn, one [3fe-4s](0,+1), and two [4fe-4s](+1,+2) clusters. the structure of the alpha subunit has been determined providing information on the mechanism of ammonia transfer from l-glutamine to 2-oxoglutarate through a 30 a-long intramolecular tunnel. on the contrary, details of the electron tran ... | 2005 | 15797248 |
| azospirillum brasilense produces the auxin-like phenylacetic acid by using the key enzyme for indole-3-acetic acid biosynthesis. | an antimicrobial compound was isolated from azospirillum brasilense culture extracts by high-performance liquid chromatography and further identified by gas chromatography-mass spectrometry as the auxin-like molecule, phenylacetic acid (paa). paa synthesis was found to be mediated by the indole-3-pyruvate decarboxylase, previously identified as a key enzyme in indole-3-acetic acid (iaa) production in a. brasilense. in minimal growth medium, paa biosynthesis by a. brasilense was only observed in ... | 2005 | 15812004 |
| enhanced swarming of bacteria on agar plates containing the surfactant tween 80. | a widely used method for quantifying swarming motility is the swarm plate assay. a significant increase in the motility halo size formed by escherichia coli or azospirillum brasilense was measured on tween 80-containing agar relative to untreated agar. this improvement could benefit the identification of mutants in swarming motility. | 2005 | 15823402 |
| nitric oxide is involved in the azospirillum brasilense-induced lateral root formation in tomato. | azospirillum spp. is a well known plant-growth-promoting rhizobacterium. azospirillum-inoculated plants have shown to display enhanced lateral root and root hair development. these promoting effects have been attributed mainly to the production of hormone-like substances. nitric oxide (no) has recently been described to act as a signal molecule in the hormonal cascade leading to root formation. however, data on the possible role of no in free-living diazotrophs associated to plant roots, is unav ... | 2005 | 15824907 |
| transcriptional analysis of the azospirillum brasilense indole-3-pyruvate decarboxylase gene and identification of a cis-acting sequence involved in auxin responsive expression. | expression of the azospirillum brasilense ipdc gene, encoding an indole-3-pyruvate decarboxylase, a key enzyme in the production of indole-3-acetic acid (iaa) in this bacterium, is upregulated by iaa. here, we demonstrate that the ipdc gene is the promoter proximal gene in a bicistronic operon. database searches revealed that the second gene of this operon, named iaac, is well conserved evolutionarily and that the encoded protein is homologous to the escherichia coli protein scrp-27a, the zebraf ... | 2005 | 15828683 |
| growth and indole-3-acetic acid biosynthesis of azospirillum brasilense sp245 is environmentally controlled. | batch and fed batch cultures of azospirillum brasilense sp245 were conducted in a bioreactor. growth response, iaa biosynthesis and the expression of the ipdc gene were monitored in relation to the environmental conditions (temperature, availability of a carbon source and aeration). a. brasilense can grow and produce iaa in batch cultures between 20 and 38 degrees c in a standard minimal medium (mmab) containing 2.5 gl(-1)l-malate and 50 microgml(-1) tryptophan. iaa synthesis requires depletion ... | 2005 | 15869971 |
| functional analysis of the gaf domain of nifa in azospirillum brasilense: effects of tyr-->phe mutations on nifa and its interaction with glnb. | regulation of nifa activity in azospirillum brasilense depends on glnb (a pii protein), and it was previously reported that the target of glnb activity is the n-terminal domain of nifa. furthermore, mutation of the tyr residue at position 18 in the n-terminal domain resulted in a nifa protein that did not require glnb for activity under nitrogen fixation conditions. we report here that a nifa double mutant in which the tyr residues at positions 18 and 53 of nifa n-were simultaneously replaced by ... | 2005 | 15887032 |
| [the electrooptical parameters of suspensions of escherichia coli xl-1 cells interacting with helper phage m13k07]. | the electrophysical properties of escherichia coli xl-1 cells interacting with helper phage m13k07 were studied as a function of the phage-to-cell ratio and the contact time. the electro-optical signal of bacterial cells changed considerably as soon as 10 min after the onset of their incubation with phage particles, presumably due to phage adsorption on the cell surface. the maximum changes in the orientational spectra of cell suspensions were observed when the phage-to-cell ratio was 20. select ... | 2005 | 15938396 |
| [analysis of dna, lipopolysaccharide structure, and some cultural and morphological properties in closely related strains of azospirillum brasilense]. | we studied closely related azospirillum brasilense strains sp7 and cd. for probing of their genomes, the fragments of 85-mda (p85) and 120-mda (p120) from a. brasilense sp245 plasmids were hybridized with 115-mda (p115) and 90-mda (p90) plasmids of strain sp7, respectively. strain cd was found to lose the 115-mda plasmid and one of the two ecori restriction fragments of the total dna (localized within p115 and the chromosome) that was homologous to an ecori-generated p85 fragment of 2.4 kb. on t ... | 2005 | 15938399 |
| isolation of transposon mutants from azospirillum brasilense yu62 and characterization of genes involved in indole-3-acetic acid biosynthesis. | the molecular genetics of indole-3-acetic (iaa) synthesis and regulation in azospirillum brasilense was investigated in this study. tn5 mutagenesis was performed and five mutants with decreased iaa production were isolated. five tn5-inserted genes from these mutants were cloned and sequenced. four genes were reported for the first time to be involved in iaa production, namely, atra, ftsa, omaa and alda that code for gntr-family transcriptional regulator, iron-binding protein component of abc-typ ... | 2005 | 15961260 |
| image analysis for quantification of bacterial rock weathering. | a fast, quantitative image analysis technique was developed to assess potential rock weathering by bacteria. the technique is based on reduction in the surface area of rock particles and counting the relative increase in the number of small particles in ground rock slurries. this was done by recording changes in ground rock samples with an electronic image analyzing process. the slurries were previously amended with three carbon sources, ground to a uniform particle size and incubated with rock ... | 2006 | 15982765 |
| the effect of native and acc deaminase-containing azospirillum brasilense cd1843 on the rooting of carnation cuttings. | carnation cuttings treated with non-transformed and 1-aminocyclopropane (acc) deaminase-containing azospirillum brasilense cd1843 produced significantly more roots than untreated controls and fewer roots than cuttings treated with 0.1% indolebutyric acid (iba). the roots produced by cuttings treated with acc deaminase-containing azospirillum brasilense cd1843 were the longest roots resulting from any of the treatments, followed by non-transformed azospirillum brasilense cd1843, 0.1% iba, and tre ... | 2005 | 16121231 |
| novel lectin-like bacteriocins of biocontrol strain pseudomonas fluorescens pf-5. | bacteriocin llpa, produced by pseudomonas sp. strain bw11m1, is a peculiar antibacterial protein due to its homology to mannose-binding lectins mostly found in monocots (a. h. a. parret, g. schoofs, p. proost, and r. de mot, j. bacteriol. 185:897-908, 2003). biocontrol strain pseudomonas fluorescens pf-5 contains two llpa-like genes, named llpa1(pf-5) and llpa2(pf-5). recombinant escherichia coli cells expressing llpa1(pf-5) or llpa2(pf-5) acquired bacteriocin activity and secreted a 31-kda prot ... | 2005 | 16151105 |
| structure and sequence conservation of hao cluster genes of autotrophic ammonia-oxidizing bacteria: evidence for their evolutionary history. | comparison of the organization and sequence of the hao (hydroxylamine oxidoreductase) gene clusters from the gammaproteobacterial autotrophic ammonia-oxidizing bacterium (aaob) nitrosococcus oceani and the betaproteobacterial aaob nitrosospira multiformis and nitrosomonas europaea revealed a highly conserved gene cluster encoding the following proteins: hao, hydroxylamine oxidoreductase; orf2, a putative protein; cyca, cytochrome c(554); and cycb, cytochrome c(m)(552). the deduced protein sequen ... | 2005 | 16151127 |
| nitrogenase switch-off by ammonium ions in azospirillum brasilense requires the glnb nitrogen signal-transducing protein. | nitrogenase activity in several diazotrophs is switched off by ammonium and reactivated after consumption. the signaling pathway to this system in azospirillum brasilense is not understood. we show that ammonium-dependent switch-off through adp-ribosylation of fe protein was partial in a glnb mutant of a. brasilense but absent in a glnb glnz double mutant. triggering of inactivation by anaerobic conditions was not affected in either mutant. the results suggest that glnb is necessary for full amm ... | 2005 | 16151168 |
| differential roles of the universal stress proteins of escherichia coli in oxidative stress resistance, adhesion, and motility. | the universal stress protein (uspa) superfamily encompasses a conserved group of proteins that are found in bacteria, archaea, and eukaryotes. escherichia coli harbors six usp genes--uspa, -c, -d, -e, -f, and -g--the expression of which is triggered by a large variety of environmental insults. the uspa gene is important for survival during cellular growth arrest, but the exact physiological role of the usp proteins is not known. in this work we have performed phenotypic characterization of mutan ... | 2005 | 16159758 |
| restoration of gibberellin production in fusarium proliferatum by functional complementation of enzymatic blocks. | nine biological species, or mating populations (mps), denoted by letters a to i, and at least 29 anamorphic fusarium species have been identified within the gibberella fujikuroi species complex. members of this species complex are the only species of the genus fusarium that contain the gibberellin (ga) biosynthetic gene cluster or at least parts of it. however, the ability of fusaria to produce gas is so far restricted to fusarium fujikuroi, although at least six other mps contain all the genes ... | 2005 | 16204516 |
| inoculation with the plant-growth-promoting rhizobacterium azospirillum brasilense causes little disturbance in the rhizosphere and rhizoplane of maize (zea mays). | inoculation with azospirillum brasilense exerts beneficial effects on plant growth and crop yields. in this study, a comparative analysis of maize (zea mays) root inoculated or not inoculated with a. brasilense strains was performed in two soils. colonization dynamics of the rhizobacteria were tracked in various root compartments using 16s rrna-targeted probes and 4',6'diamidino-2-phenylindole staining, and the structure of bacterial populations in the same samples was analyzed by denaturing gra ... | 2005 | 16211327 |
| [plasmid rearrangements in azospirillum brasilense]. | | 2005 | 16211863 |
| the nodpq genes in azospirillum brasilense sp7 are involved in sulfation of lipopolysaccharides. | here we report on the presence of sulfated lipopolysaccharide molecules in azospirillum brasilense, a plant growth-promoting rhizosphere bacterium. chemical analysis provided structural data on the o-antigen composition and demonstrated the possible involvement of the nodpq genes in o-antigen sulfation. | 2005 | 16232291 |
| comparative in situ analysis of ipdc-gfpmut3 promoter fusions of azospirillum brasilense strains sp7 and sp245. | inoculation of wheat roots with azospirillum brasilense results in an increase of plant growth and yield, which is proposed to be mainly due to the bacterial production of indole-3-acetic acid in the rhizosphere. field inoculation experiments had revealed more consistent plant growth stimulation using a. brasilense strain sp245 as compared with the strain sp7. therefore, the in situ expression of the key gene ipdc (indole-3-pyruvate decarboxylase) was examined in these two strains. within the ip ... | 2005 | 16232298 |
| azospirillum brasilense does not affect population structure of specific rhizobacterial communities of inoculated maize (zea mays). | positive response of plant species to plant growth-promoting rhizobacteria have led to an increased interest in their use as bacterial inoculants. however, the introduction of exogenous bacteria into natural ecosystems may perturb bacterial populations within the microbial community and lead to the disruption of indigenous populations performing key functional roles. in this study the effect of azospirillum brasilense inoculation on maize (zea mays) rhizosphere actinobacteria, bacteroidetes, alp ... | 2005 | 16232299 |
| effect of the over-expression of pii and pz proteins on the nitrogenase activity of azospirillum brasilense. | the azospirillum brasilense pii and pz proteins, encoded by the glnb and glnz genes respectively, are intracellular transducers of nitrogen levels with distinct functions. the pii protein participates in nif regulation by controlling the activity of the transcriptional regulator nifa. pii is also involved in transducing the prevailing nitrogen levels to the fe-protein adp-ribosylation system. pz regulates negatively ammonium transport and is involved in nitrogenase reactivation. to further inves ... | 2005 | 16239079 |
| effects of heavy metals on plant-associated rhizobacteria: comparison of endophytic and non-endophytic strains of azospirillum brasilense. | the plant-associated nitrogen-fixing rhizobacterium azospirillum brasilense attracts world-wide attention owing to its plant growth-promoting activities. among hundreds of its strains known up to date, wild-type strain sp245 has been proved to be capable of colonising both the plant-root interior and exterior (i.e. a facultative endophyte), whereas others are non-endophytes colonising the root surface only. thus, the different ecological niches occupied by these strains in the rhizosphere sugges ... | 2005 | 16240678 |
| evidence for horizontal transfer of 1-aminocyclopropane-1-carboxylate deaminase genes. | pcr was used to rapidly identify and isolate 1-aminocyclopropane-1-carboxylate (acc) deaminase genes from bacteria. the shimodaira-hasegawa test was used to assess whether phylogenetically anomalous gene placements suggestive of horizontal gene transfer (hgt) were significantly favored over vertical transmission. the best maximum likelihood (ml) acc deaminase tree was significantly more likely than four alternative ml trees, suggesting hgt. | 2005 | 16269802 |
| [determination of the structure of the repeated unit of the azospirillum brasilense sr75 o-specific polysaccharide and homology of the lps loci in the plasmids of azospirillum brasilense strains sr75 and sp245]. | the structural identity of the repeated unit in o-specific polysaccharides (opss) present in the outer membrane of strain sr75 of the bacterium azospirillum brasilense, isolated from wheat rhizosphere in saratov oblast, and the opss of previously studied a. brasilense strain sp245, isolated from surface-sterilized wheat roots in brazil, has been demonstrated. plasmid profiles, dna restriction, and hybridization assays suggested that a. brasilense strains sr75 and sp245 have different genomic str ... | 2005 | 16315981 |
| cloning, expression, and characterization of bacterial l-arabinose 1-dehydrogenase involved in an alternative pathway of l-arabinose metabolism. | azospirillum brasiliense converts l-arabinose to alpha-ketoglutarate via five hypothetical enzymatic steps. we purified and characterized l-arabinose 1-dehydrogenase (ec 1.1.1.46), catalyzing the conversion of l-arabinose to l-arabino-gamma-lactone as an enzyme responsible for the first step of this alternative pathway of l-arabinose metabolism. the purified enzyme preferred nadp+ to nad+ as a coenzyme. kinetic analysis revealed that the enzyme had high catalytic efficiency for both l-arabinose ... | 2006 | 16326697 |
| cultivation factors and population size control the uptake of nitrogen by the microalgae chlorella vulgaris when interacting with the microalgae growth-promoting bacterium azospirillum brasilense. | growth of and the capacity to take up nitrogen in the freshwater microalgae chlorella vulgaris were studied while varying the concentrations of ammonium and nitrate, the ph and the source of carbon in a synthetic wastewater growth medium when co-immobilized in alginate beads with the microalgae growth-promoting bacterium azospirillum brasilense. analyses of 29 independent experiments showed that co-immobilization of the microalgae with a. brasilense could result in two independent phenomena dire ... | 2005 | 16332319 |
| methods for growing spirillum lipoferum and for counting it in pure culture and in association with plants. | methods are described for growing spirillum lipoferum in quantities sufficient to serve as inoculant in field trials of its associative n(2)-fixing ability with higher plants and as a source of cells for the preparation of nitrogenase, cytochromes, respiratory enzymes, etc. a heavy inoculum of s. lipoferum grown on nh(4) was transferred to a medium of minimal nitrogen content, and initial rapid growth at the expense of residual combined nitrogen was replaced later by slower growth on n(2). conve ... | 1977 | 16345192 |
| plant growth substances produced by azospirillum brasilense and their effect on the growth of pearl millet (pennisetum americanum l.). | azospirillum brasilense, a nitrogen-fixing bacterium found in the rhizosphere of various grass species, was investigated to establish the effect on plant growth of growth substances produced by the bacteria. thin-layer chromatography, high-pressure liquid chromatography, and bioassay were used to separate and identify plant growth substances produced by the bacteria in liquid culture. indole acetic acid and indole lactic acid were produced by a. brasilense from tryptophan. indole acetic acid pro ... | 1979 | 16345372 |
| characterization of azospirillum isolated from nitrogen-fixing roots of harvested sorghum plants. | root segments of harvested sorghum plants had acetylene reduction activity ranging from 11 to 61 nmol of ethylene formed per h per g (dry weight). five strains of azospirillum brasilense sp. nov. were isolated from root segments. | 1979 | 16345484 |
| association of azospirillum with grass roots. | the association between grass roots and azospirillum brasilense sp 7 was investigated by the fahraeus slide technique, using nitrogen-free medium. young inoculated roots of pearl millet and guinea grass produced more mucilaginous sheath (mucigel), root hairs, and lateral roots than did uninoculated sterile controls. the bacteria were found within the mucigel that accumulated on the root cap and along the root axes. adherent bacteria were associated with granular material on root hairs and fibril ... | 1980 | 16345490 |
| biology of azospirillum-sugarcane association: enhancement of nitrogenase activity. | azospirillum brasilense was reisolated from associations with callus tissue cultures of sugarcane and compared with stock cultures of the inoculated bacterium and related strains. although the reisolate had a growth rate similar to stock cultures, it exhibited a severalfold increase in maximum specific activity of nitrogenase. the reisolate and the parent culture had similar ultrastructure. the general ultrastructure of azospirillum is described. the bacterium was capsulated when grown on nitrog ... | 1980 | 16345531 |
| plant yield and nitrogen content of a digitgrass in response to azospirillum inoculation. | two australian soils, a vertisol (ph 6.8, 0.299% n) and a sandy yellow podzol (ph 6.2, 0.042% n), were used with digitgrass, digitaria sp. x46-2 (pi 421785), in a growth room experiment. comparisons were made between plants inoculated with live and autoclaved bacterial suspensions of australian and brazilian isolates of azospirillum brasilense. seedlings were inoculated on days 10 and 35. acetylene-reducing activity was measured five times during the experiment. dry matter yields of the digitgra ... | 1981 | 16345707 |
| enhanced mineral uptake by zea mays and sorghum bicolor roots inoculated with azospirillum brasilense. | inoculation of corn (zea mays) seeds with azospirillum brasilense strain cd or sp 7 significantly enhanced (30 to 50% over controls) the uptake of no(3), k, and h(2)po(4) into 3- to 4-day- and 2-week-old root segments. no gross changes in root morphology were observed; altered cell arrangement in the outer four or five layers of the cortex was seen in photomicrographs of cross sections of inoculated corn roots. the surface activity involved in ion uptake probably increased, as shown by the darke ... | 1983 | 16346311 |