Publications

continuous monitoring of nitrogenase activity in azotobacter vinelandii fermentation using off-gas mass spectrometry.	this study evaluated the feasibility of monitoring nitro-genase activity in situ through measurement of n(2) uptake rate (nur) using off-gas mass spectrometry. four 50-l cultures of azotobacter vinelandii were grown aer-obically in nitrogen-free medium to cell densities of 1.0-1.3gl(-1) magnetic-sector mass spectrometer was used to monitor nur along with other gas exchange rates. the small specific uptake rate (1.2 mmol g(-1) h(-1)) and low cell density were found to lead to a nur below the meas ...	1995	18623412
stabilization of fully reduced iron-sulfur clusters by carbene ligation: the [fensn]0 oxidation levels (n = 4, 8).	the all-ferrous [fe4s4](0) state has been demonstrated in the fully reduced fe protein of the azotobacter vinelandii nitrogenase complex. we seek synthetic analogues of this state more tractable than the recently prepared but highly unstable cluster [fe4s4(cn)4](4-) (scott, berlinguette, holm, and zhou, proc. natl. acad. sci. u.s.a. 2005, 102, 9741). the n-heterocyclic carbene 1,3-diisopropyl-4,5-dimethylimidazol-2-ylidene (pr(i)2nhcme2) has been found to stabilize the fully reduced clusters [fe ...	2008	18593124
structural and mutational characterization of the catalytic a-module of the mannuronan c-5-epimerase alge4 from azotobacter vinelandii.	alginate is a family of linear copolymers of (1-->4)-linked beta-d-mannuronic acid and its c-5 epimer alpha-l-guluronic acid. the polymer is first produced as polymannuronic acid and the guluronic acid residues are then introduced at the polymer level by mannuronan c-5-epimerases. the structure of the catalytic a-module of the azotobacter vinelandii mannuronan c-5-epimerase alge4 has been determined by x-ray crystallography at 2.1-a resolution. alge4a folds into a right-handed parallel beta-heli ...	2008	18574239
in vivo iron-sulfur cluster formation.	it has been proposed that iron-sulfur [fe-s] clusters destined for the maturation of [fe-s] proteins can be preassembled on a molecular scaffold designated iscu. in the present article, it is shown that production of the intact azotobacter vinelandii [fe-s] cluster biosynthetic machinery at levels exceeding the amount required for cellular maturation of [fe-s] proteins results in the accumulation of: (i) apo-iscu, (ii) an oxygen-labile [2fe-2s] cluster-loaded form of iscu, and (iii) iscu complex ...	2008	18562278
effect of dissolved oxygen on nitrogen fixation by a. vinelandii. ii. ionically adsorbed cells.	continuous culture studies of azotobacter vinelandii cells immobilized by ionic adsorption to cellex e anion exchange resin were conducted under oxygen-limited conditions for comparison to free-cell cultures. immobilization had little effect upon the specific respiration and sucrose consumption rates as compared to free cells. however, maxima in specific nitrogen fixation rate and nitrogenase activity as a function of dissolved oxygen occurred at a c(o(2) ) value of approximately 0.005 mm as opp ...	1984	18551591
effect of dissolved oxygen on nitrogen fixation by a. vinelandii. i. free cell cultures.	as part of an investigation into the use of biological nitrogen fixation for fertilizer ammonia production, continuous culture studies of respiration and nitrogen fixation in the aerobic bacteria azotobacter vinelandii under oxygen-limited conditions were conducted. respiration and growth rates followed monod forms with respect to dissolved oxygen concentration. however, specific nitrogen fixation rate and nitrogenase activity exhibited maximum values at dissolved oxygen concentrations of ca. 0. ...	1984	18551590
flhdc, but not fleq, regulates flagella biogenesis in azotobacter vinelandii, and is under algu and cydr negative control.	azotobacter vinelandii is a nitrogen-fixing soil bacterium that undergoes differentiation to form cysts resistant to desiccation. upon encystment, this bacterium becomes non-motile. as in enteric bacteria, motility in a. vinelandii occurs through the use of peritrichous flagella. pseudomonas aeruginosa, a phylogenetically close relative of a. vinelandii, possesses a single polar flagellum. the flhdc proteins are the master regulators of flagella and motility in enterobacteria, whereas fleq is th ...	2008	18524926
eukaryotic and bacterial gene clusters related to an alternative pathway of nonphosphorylated l-rhamnose metabolism.	the entner-doudoroff (ed) pathway is a classic central pathway of d-glucose metabolism in all three phylogenetic domains. on the other hand, archaea and/or bacteria possess several modified versions of the ed pathway, in which nonphosphorylated intermediates are involved. several fungi, including pichia stipitis and debaryomyces hansenii, possess an alternative pathway of l-rhamnose metabolism, which is different from the known bacterial pathway. gene cluster related to this hypothetical pathway ...	2008	18505728
catechol siderophores control tungsten uptake and toxicity in the nitrogen-fixing bacterium azotobacter vinelandii.	molybdenum (mo) and tungsten (w), which have similar chemistry, are present at roughly the same concentration in the earth's continental crust, and both are present in oxic systems as oxoanions, molybdate and tungstate. molybdenum is a cofactor in the molybdenum-nitrogenase enzyme and is thus an important micronutrient for n2-fixing bacteria such as azotobacter vinelandii (a. vinelandii). tungsten is known to be toxic to n2-fixing bacteria, partly by substituting for mo in nitrogenase. we showth ...	2008	18504973
semi-continuum electrostatic calculations of redox potentials in photosystem i.	the midpoint redox potentials (e(m)) of all cofactors in photosystem i from synechococcus elongatus as well as of the iron-sulfur (fe(4)s(4)) clusters in two soluble ferredoxins from azotobacter vinelandii and clostridium acidiurici were calculated within the framework of a semi-continuum dielectric approach. the widely used treatment of proteins as uniform media with single dielectric permittivity is oversimplified, particularly, because permanent charges are considered both as a source for int ...	2008	18483776
structural insights into biosynthesis of resorcinolic lipids by a type iii polyketide synthase in neurospora crassa.	microbial type iii polyketide synthases (pkss) have revealed remarkable mechanistic as well as functional versatility. recently, a type iii pks homolog from azotobacter has been implicated in the biosynthesis of resorcinolic lipids, thus adding a new functional significance to this class of proteins. here, we report the structural and mutational investigations of a novel type iii pks protein from neurospora crassa involved in the biosynthesis of resorcinolic metabolites by utilizing long chain f ...	2008	18462950
distribution of bacteria and fungi in the earthworm libyodrillus violaceous (annelida: oligochaeta), a native earthworm from nigeria.	earthworms are soil invertebrates that play a key role in recycling organic matter in soils. in nigeria, earthworms include libyodrillus violaceous. aerobic and anaerobic bacterial counts, as well as fungal counts of viable microorganisms in soils and gut sections, were made on twenty l. violaceous collected from different sites on the campus of the university of agriculture, abeokuta, nigeria. the samples were collected between april and november, 2002. numbers of microorganisms were higher in ...	2006	18457174
extended x-ray absorption fine structure and nuclear resonance vibrational spectroscopy reveal that nifb-co, a femo-co precursor, comprises a 6fe core with an interstitial light atom.	nifb-co, an fe-s cluster produced by the enzyme nifb, is an intermediate on the biosynthetic pathway to the iron molybdenum cofactor (femo-co) of nitrogenase. we have used fe k-edge extended x-ray absorption fine structure (exafs) spectroscopy together with (57)fe nuclear resonance vibrational spectroscopy (nrvs) to probe the structure of nifb-co while bound to the nifx protein from azotobacter vinelandii. the spectra have been interpreted in part by comparison with data for the completed femo-c ...	2008	18386899
growth of avicennia marina and ceriops decandra seedlings inoculated with halophilic azotobacters.	inoculation of azotobacter has significant positive effects on the growth characteristics and pigments in mangrove seedlings of avicennia marina and ceriops decandra. the bacterial inoculation significantly increased the root dry biomass at the maximum of 75.8% at 30 gl(-1) salinity in ceriops decandra. but in avicennia marina, the shoot dry biomass was increased significantly at the maximum of 56.12% at 30 gl(-1) salinity in general, the azotobacter beijerinkii improved the growth characteristi ...	2007	18380082
characterization of diazotrophs containing mo-independent nitrogenases, isolated from diverse natural environments.	molybdenum-independent nitrogenases were first described in the nitrogen-fixing bacterium azotobacter vinelandii and have since been described in other diazotrophic bacteria. previously, we reported the isolation of seven diazotrophs with mo-independent nitrogenases from aquatic environments. in the present study, we extend these results to include diazotrophs isolated from wood chip mulch, soil, "paraffin dirt," and sediments from mangrove swamps. mo-deficient, n-free media under both aerobic a ...	2008	18378646
the azotobacter vinelandii alge mannuronan c-5-epimerase family is essential for the in vivo control of alginate monomer composition and for functional cyst formation.	the industrially widely used polysaccharide alginate is a co-polymer of beta-d-mannuronic acid and alpha-l-guluronic acid (g), and the g residues originate from a polymer-level epimerization process catalysed by mannuronan c-5-epimerases. in the genome of the alginate-producing bacterium azotobacter vinelandii genes encoding one periplasmic (algg) and seven secreted such epimerases (alge1-7) have been identified. here we report the generation of a strain (ms163171) in which all the alge genes we ...	2008	18373676
phylogenetic diversity of nitrogen-fixing bacteria in mangrove sediments assessed by pcr-denaturing gradient gel electrophoresis.	culture-independent pcr-denaturing gradient gel electrophoresis (dgge) was employed to assess the composition of diazotroph species from the sediments of three mangrove ecosystem sites in sanya, hainan island, china. a strategy of removing humic acids prior to dna extraction was conducted, then total community dna was extracted using the soil dna kit successfully for nifh pcr amplification, which simplified the current procedure and resulted in good dgge profiles. the results revealed a novel ni ...	2008	18347779
a proposed role for the azotobacter vinelandii nfua protein as an intermediate iron-sulfur cluster carrier.	iron-sulfur clusters ([fe-s] clusters) are assembled on molecular scaffolds and subsequently used for maturation of proteins that require [fe-s] clusters for their functions. previous studies have shown that azotobacter vinelandii produces at least two [fe-s] cluster assembly scaffolds: nifu, required for the maturation of nitrogenase, and iscu, required for the general maturation of other [fe-s] proteins. a. vinelandii also encodes a protein designated nfua, which shares amino acid sequence sim ...	2008	18339629
[effects of successive cropping rehmannia glutinosa on rhizosphere soil microbial flora and enzyme activities].	with the soils cropped rehmannia glutinosa for one and two years as test materials, this paper studied the variations of microbial flora and enzyme activities in rhizosphere. the results showed that with increasing year of cropping, the numbers of bacteria and fungi in rihzosphere had a slight decrease. in the soil successively cropped r. glutinosa for two years, the number of actinomycetes in rihzosphere was 4 times higher, the ammonifier, aerobic azotobacter, sulphate reducer, denitrifier, and ...	2007	18333450
is vanadium a more versatile target in the activity of primordial life forms than hitherto anticipated?	the two predominant forms of vanadium occurring in the geo-, aqua- and biosphere, soluble vanadate(v) and insoluble oxovanadium(iv) (vanadyl), are subject to bacterial activity and transformation. bacteria belonging to genera such as shewanella, pseudomonas and geobacter can use vanadate as a primary electron acceptor in dissimilation or respiration, an important issue in the context of biomineralisation and soil detoxification. azotobacter, which can employ vanadium as an essential element in n ...	2008	18327316
catalytic properties of na+-translocating nadh:quinone oxidoreductases from vibrio harveyi, klebsiella pneumoniae, and azotobacter vinelandii.	the catalytic properties of sodium-translocating nadh:quinone oxidoreductases (na+-nqrs) from the marine bacterium vibrio harveyi, the enterobacterium klebsiella pneumoniae, and the soil microorganism azotobacter vinelandii have been comparatively analyzed. it is shown that these enzymes drastically differ in their affinity to sodium ions. the enzymes also possess different sensitivity to inhibitors. na+-nqr from a. vinelandii is not sensitive to low 2-n-heptyl-4-hydroxyquinoline n-oxide (hqno) ...	2008	18300384
azotobacter vinelandii metal storage protein: "classical" inorganic chemistry involved in mo/w uptake and release processes.	the release of mo (as molybdate) from the mo storage protein (mosto), which is unique among all existing metalloproteins, is strongly influenced by temperature and ph value; other factors (incubation time, protein concentration, degree of purity) have minor, though significant effects. a detailed ph titration at 12 degrees c revealed that three different steps can be distinguished for the mo-release process. a proportion of approximately 15% at ph 6.8-7.0, an additional 25% at ph 7.2-7.5 and ca. ...	2008	18273850
biological removal of cr (vi) by bacterial isolates obtained from metal contaminated sites.	present study demonstrates the application of indigenous bacteria and pure culture of azotobacter for removal of cr (vi) from the aqueous solution and industrial effluent. minimum inhibitory concentration (mic) was determined for 3 bacterial isolates (b1, b2, b3) and pure culture of azotobacter. the effect of various parameters such as effect of initial cr (vi) concentration, biomass dose, and time were examined to study the biosorption and bioaccumulation separately using live and dead cells, r ...	2008	18273748
functional participation of a nifh-arsa2 chimeric fusion gene in arsenic reduction by escherichia coli.	the nifh (dimer) and arsa proteins are structural homologs and share common motifs like nucleotide-binding domains, signal transduction domains and also possible similar metal center ligands. given the similarity between two proteins, we investigated if the nifh protein from azotobacter vinelandii could functionally substitute for the arsa1 half of the arsa protein of escherichia coli. the chimeric nifh-arsa2 protein was expressed and detected in the e. coli strain by western blotting. growth co ...	2008	18230343
direct transfer of starter substrates from type i fatty acid synthase to type iii polyketide synthases in phenolic lipid synthesis.	alkylresorcinols and alkylpyrones, which have a polar aromatic ring and a hydrophobic alkyl chain, are phenolic lipids found in plants, fungi, and bacteria. in the gram-negative bacterium azotobacter vinelandii, phenolic lipids in the membrane of dormant cysts are essential for encystment. the aromatic moieties of the phenolic lipids in a. vinelandii are synthesized by two type iii polyketide synthases (pkss), arsb and arsc, which are encoded by the ars operon. however, details of the synthesis ...	2008	18199837
vanadium requirements and uptake kinetics in the dinitrogen-fixing bacterium azotobacter vinelandii.	vanadium is a cofactor in the alternative v-nitrogenase that is expressed by some n(2)-fixing bacteria when mo is not available. we investigated the v requirements, the kinetics of v uptake, and the production of catechol compounds across a range of concentrations of vanadium in diazotrophic cultures of the soil bacterium azotobacter vinelandii. in strain ca11.70, a mutant that expresses only the v-nitrogenase, v concentrations in the medium between 10(-8) and 10(-6) m sustain maximum growth rat ...	2008	18192412
recent advances in nitrogen-fixing acetic acid bacteria.	nitrogen is an essential plant nutrient, widely applied as n-fertilizer to improve yield of agriculturally important crops. an interesting alternative to avoid or reduce the use of n-fertilizers could be the exploitation of plant growth-promoting bacteria (pgpb), capable of enhancing growth and yield of many plant species, several of agronomic and ecological significance. pgpb belong to diverse genera, including azospirillum, azotobacter, herbaspirillum, bacillus, burkholderia, pseudomonas, rhiz ...	2008	18177965
[antibacterial activity of polyphenolic compounds isolated from plants of geraniaceae and rosaceae families].	polyphenolic compounds present in extracts of plants belonging to the families geraniaceae (blood-red cranesbill, wood cranesbill, meadow cranesbill, and alfilaria) and rosaceae (red raspberry, european dewberry, and tormentil) have been tested for their activity against gram-positive and gram-negative bacteria of the genera azotobacter, bacillus, and pseudomonas. the bacteriostatic activity exhibited some species-related features and depended on the polarity of the extracting agent. the bacteri ...	2007	18173115
the influence of process parameters on the characteristics of polyhydroxyalkanoates produced by mixed cultures.	the characterization of polyhydroxyalkanoates (pha) produced by mixed cultures is fundamental for foreseeing the possible final applications of the polymer. in this study pha produced under aerobic dynamic feeding (adf) conditions are characterized. the pha produced shows a stable average molecular weight ([symbol: see text]) in the range (1.0-3.0) x 10(6), along three years of reactor operation. attempts to improve the amount of pha produced did not introduce significant variations on the value ...	2008	18157852
the oxalacetate decarboxylase of azotobacter vinelandii.		1949	18146549
hydroxylamine as a source of nitrogen for azotobacter vinelandii.		1949	18108880
rpos expression and the general stress response in azotobacter vinelandii during carbon and nitrogen diauxic shifts.	the general stress response mediated by the sigma factor rpos is important for survival of bacteria in adverse environments. a mutant unable to produce rpos was constructed using the diazotrophic bacterium azotobacter vinelandii strain uw. under nondesiccating, solid-medium growth conditions the wild type was culturable for 16.5 years, while the rpos mutant remained viable for only 10 months. the rpos mutant exhibited reduced survival compared to the wild type following hydrogen peroxide stress, ...	2008	18055600
identification of two catalases in azotobacter vinelandii: a katg homologue and a novel bacterial cytochrome c catalase, cccav.	azotobacter vinelandii produces two detectable catalases during growth on minimal medium. the heat-labile catalase expressed during exponential growth phase was identified as a katg homologue by liquid chromatography-tandem mass spectrometry (lc-ms/ms) using a mixed protein sample. the second catalase was heat resistant and had substantial residual activity after treatment at 90 degrees c. this enzyme was purified by anion-exchange and size exclusion chromatography and was found to exhibit stron ...	2008	18055590
microcosm study for revegetation of barren land with wild plants by some plant growth-promoting rhizobacteria.	growth promotion of wild plants by some plant growth-promoting rhizobacteria (pgpr) was examined in the microcosms composed of soils collected separately from a grass-covered site and a nongrass-covered site in a lakeside barren area at lake paro, korea. after sowing the seeds of eight kinds of wild plants and inoculation of several strains of pgpr, the total bacterial number and microbial activity were measured during 5 months of study period, and the plant biomasses grown were compared at the ...	2007	18051353
probable synonymy of the nitrogen-fixing genus azotobacter and the genus pseudomonas.	the relationships of the genus azotobacter, azomonas macrocytogenes and the genus pseudomonas were revealed by comparative analysis of partial 16s rrna and atpd, cara and reca gene sequences and as concatenated nucleotide and peptide sequences. sequence similarities of azotobacter species and azomonas macrocytogenes indicated that these may be considered to be synonyms at the molecular level. in addition, these species show an intimate relationship with species of pseudomonas, especially p. aeru ...	2007	18048745
probing the mgatp-bound conformation of the nitrogenase fe protein by solution small-angle x-ray scattering.	the mgatp-bound conformation of the fe protein of nitrogenase from azotobacter vinelandii has been examined in solution by small-angle x-ray scattering (saxs) and compared to existing crystallographically characterized fe protein conformations. the results of the analysis of the crystal structure of an fe protein variant with a switch ii single-amino acid deletion recently suggested that the mgatp-bound state of the fe protein may exist in a conformation that involves a large-scale reorientation ...	2007	18001132
phytoremediation of coal mine spoil dump through integrated biotechnological approach.	field experiment was conducted on mine spoil dump on an area of 10 ha, to restore the fertility and productivity of the coal mine spoil dump using integrated biotechnological approach. the approach involves use of effluent treatment plant sludge (etp sludge), as an organic amendment, biofertilizers and mycorrihzal fungi along with suitable plant species. the results of the study indicated that amendment with effluent treatment plant sludge (etp sludge), @ 50 ton/ha improved the physico-chemical ...	2008	17980580
in vitro synthesis of the iron-molybdenum cofactor of nitrogenase from iron, sulfur, molybdenum, and homocitrate using purified proteins.	biological nitrogen fixation, the conversion of atmospheric n2 to nh3, is an essential process in the global biogeochemical cycle of nitrogen that supports life on earth. most of the biological nitrogen fixation is catalyzed by the molybdenum nitrogenase, which contains at its active site one of the most complex metal cofactors known to date, the iron-molybdenum cofactor (femo-co). femo-co is composed of 7fe, 9s, mo, r-homocitrate, and one unidentified light atom. here we demonstrate the complet ...	2007	17978192
effect of biosludge and biofertilizer amendment on growth of jatropha curcas in heavy metal contaminated soils.	the pot experiments were conducted to evaluate the effect of different concentrations of arsenic, chromium and zinc contaminated soils, amended with biosludge and biofertilizer on the growth of jatropha curcas which is a biodiesel crop. the results further showed that biosludge alone and in combination with biofertilizer significantly improved the survival rates and enhanced the growth of the plant. with the amendments, the plant was able to grow and survive upto 500, 250 and 4,000 mg kg(-1) of ...	2008	17973198
effects of granule-associated protein phap on glycerol-dependent growth and polymer production in poly(3-hydroxybutyrate)-producing escherichia coli.	polyhydroxyalkanoates (phas) are accumulated as intracellular granules by many bacteria under unfavorable conditions, enhancing their fitness and stress resistance. poly(3-hydroxybutyrate) (phb) is the most widespread and best-known pha. apart from the genes that catalyze polymer biosynthesis, natural pha producers have several genes for proteins involved in granule formation and/or with regulatory functions, such as phasins, that have been shown to affect polymer synthesis. this study evaluates ...	2007	17965215
studies on rhizosphere microbial diversity of some commercially important medicinal plants.	a preliminary study was made on four medicinal plants viz., ocimum sanctum l., coleus forskholii briq, catharanthus roseus (l.) g. don. and aloe vera in order to identify and enumerate the rhizosphere, non-rhizosphere and diazotrophic microorganisms in soil. the diazotrophic bacterial population studied includes azospirillum, azotobacter and pseudomonas. the rhizosphere bacterial populations were 23.33 x 10(6)g(-1) in o. sanctum followed by c. roseus (20.46 x 10(6)g(-1)), a. vera (18.44 x 10(6)g ...	2008	17951032
[biological fixation of nitrogen and growth of bacteria of the genus azotobacter in liquid media in the presence of perfluorocarbons].	the addition of perfluorocarbons (perfluorodecalin, carbogal, and perfluoromethyldecalin) to nitrogen-free liquid media during the submerged cultivation of bacteria of the genus azotobacter was followed by (1) increases in biomass accumulation and nitrogenase activity and (2) fixation of molecular nitrogen. addition of perfluorodecalin (5 vol %) to the culture medium of a. chroococcum acb 121 contributed to increases in biomass accumulation, cell concentration (of more than by five times), nitro ...	2007	17929572
characterization of a globin-coupled oxygen sensor with a gene-regulating function.	globin-coupled sensors (gcss) are multiple-domain transducers, consisting of a regulatory globin-like heme-binding domain and a linked transducer domain(s). gcss have been described in both archaea and bacteria. they are generally assumed to bind o(2) (and perhaps other gaseous ligands) and to transmit a conformational change signal through the transducer domain in response to fluctuating o(2) levels. in this study, the heme-binding domain, avgreg178, and the full protein, avgreg of the azotobac ...	2007	17925395
biochemical and structural characterization of pseudomonas aeruginosa bfd and fpr: ferredoxin nadp+ reductase and not ferredoxin is the redox partner of heme oxygenase under iron-starvation conditions.	among the 118 genes upregulated by pseudomonas aeruginosa in response to iron starvation [ochsner, u. a., wilderman, p. j., vasil, a. i., and vasil, m. l. (2002) mol. microbiol. 45, 1277-1287], we focused on the products of the two genes encoding electron transfer proteins, as a means of identifying the redox partners of the heme oxygenase (pa-ho) expressed under low-iron stress conditions. biochemical and spectroscopic investigations demonstrated that the bfd gene encodes a 73-amino acid protei ...	2007	17915950
establishment of azotobacter on plant roots: chemotactic response, development and analysis of root exudates of cotton (gossypium hirsutum l.) and wheat (triticum aestivum l.).	biofertilizers contribute in n(2) fixation, p solubilization, phytohormone production and thus enhance plant growth. beneficial plant-microbe interactions and the stability and effectiveness of biofertilizer depend upon the establishment of bacterial strains in the rhizosphere of the plant. this interaction depends upon many factors, one of them being plant exudates. root exudates are composed of small organic molecules like carbonic acids, amino acids or sugars etc., which are released into the ...	2007	17910096
enzyme i npr, npr and iia ntr are involved in regulation of the poly-beta-hydroxybutyrate biosynthetic genes in azotobacter vinelandii.	the ptsp, ptso, and ptsn genes encode enzyme i(ntr), npr, and enzyme iia(ntr) (iia(ntr)) proteins of the nitrogen-related phosphotransferase system. these proteins participate in a phosphoryl transfer chain in several bacteria, where iia(ntr) appears to be the terminal phosphoryl acceptor. inactivation of the ptsp gene in azotobacter vinelandii was previously shown to reduce poly-beta-hydroxybutyrate (phb) production. therefore, the question of a role of the ptso and ptsn gene products in phb sy ...	2008	17878711
conformations generated during turnover of the azotobacter vinelandii nitrogenase mofe protein and their relationship to physiological function.	various s=3/2 epr signals elicited from wild-type and variant azotobacter vinelandii nitrogenase mofe proteins appear to reflect different conformations assumed by the femo-cofactor with different protonation states. to determine whether these presumed changes in protonation and conformation reflect catalytic capacity, the responses (particularly to changes in electron flux) of the alphah195q, alphah195n, and alphaq191k variant mofe proteins (where his at position 195 in the alpha subunit is rep ...	2007	17845818
do azotobacter nitrify?		1914	17841435
soil reaction and the presence of azotobacter.		1918	17841424
uptake and continued metabolic activity of azotobacter within fungal protoplasts.	uptake of vegetative cells of azotobacter vinelandii into protoplasts of the mycorrhizal fungus rhizopogon sp. can be induced by treatment with polyethylene glycol (molecular weight, 6000). an l-form of the bacteria has been selected for within the differentiated fungal mycelium which is capable of acetylene reduction and nitrogen fixation, as confirmed by nitrogen-15 assays; this allows the fungus to grow on media lacking any combined nitrogen. the fungus grows and reduces acetylene on concentr ...	1976	17792751
cytochrome bd from azotobacter vinelandii: evidence for high-affinity oxygen binding.	cytochrome bd from azotobacter vinelandii is a respiratory quinol oxidase that is highly efficient in reducing intracellular oxygen concentration, thus enabling nitrogen fixation under ambient aerobic conditions. equilibrium measurements of o2 binding to ferrous heme d in the one-electron-reduced form of the a. vinelandii enzyme give kd(o2) = 0.5 microm, close to the value for the escherichia coli cytochrome bd (ca. 0.3 microm); thus, both enzymes have similar, high affinity for oxygen. the reac ...	2007	17784736
the occurrence of azotobacter in cranberry soils.		1918	17781964
respiration studies on azotobacter under controlled conditions.		1931	17778408
cell inclusions in azotobacter chroococcum bej.		1937	17777204
cell inclusions and the life cycle of azotobacter chroococcum.		1937	17775696
nitrogen fixation by azotobacter vinelandii strains having deletions in structural genes for nitrogenase.	phenotypic reversal of nif(-) mutant strains to nif(+) under molybdenum-deficient conditions has been cited as evidence that azotobacter vinelandii possesses two nitrogen fixation systems: the conventional molybdenum-enzyme system and an alternative nitrogen-fixation system. since explanations other than the existence of an alternative system were possible, deletion strains of a. vinelandii lacking the structural genes for conventional nitrogenase (nifhdk) were constructed. these strains were fo ...	1986	17774003
a species of azotobacter tolerant to high acidity.		1939	17758512
azotobacter in soils.		1922	17756805
the occurrence and isolation of azotobacter in chinese soils.		1940	17754411
on the presence of azotobacter agilis in america.		1939	17741475
observations on azotobacter.		1915	17737330
influence of h-ion on growth of azotobacter.		1922	17731117
survival of bio-inoculants on fungicides-treated seeds of wheat, pea and chickpea and subsequent effect on chickpea yield.	survival of mesorhizobium ciceri (sp(4)) and azotobacter chroococcum (cbd-15 and m(4)) was tested on chickpea (cicer arietinum) seeds treated with fungicides bavistin [methyl n-(1h-benzimidazol-2yl) carbamate] and thiram (tetramethyl-thiuram disulfide), whereas survival of phosphate solubilizing bacteria (psb), pseudomonas striata (27) and bacillus polymyxa (h(5)) was examined on two cultivars (arkel and bv) of pea (pisum sativum) seeds treated with thiram. viability of azotobacter chroococcum ( ...	2007	17701702
discovery of the true peroxy intermediate in the catalytic cycle of terminal oxidases by real-time measurement.	the sequence of the catalytic intermediates in the reaction of cytochrome bd terminal oxidases from escherichia coli and azotobacter vinelandii with oxygen was monitored in real time by absorption spectroscopy and electrometry. the initial binding of o(2) to the fully reduced enzyme is followed by the fast (5 micros) conversion of the oxy complex to a novel, previously unresolved intermediate. in this transition, low spin heme b(558) remains reduced while high spin heme b(595) is oxidized with f ...	2007	17690093
the polyhydroxyalkanoate genes of a stress resistant antarctic pseudomonas are situated within a genomic island.	pseudomonas sp. 14-3 is an antarctic bacterium that shows high stress resistance in association with high polyhydroxybutyrate (phb) production. in this paper genes involved in phb biosynthesis (pharbac) were found within a genomic island named pha-gi. numerous mobile elements or proteins associated with them, such as an integrase, insertion sequences, a bacterial group ii intron, a complete type i protein secretion system and incp plasmid-related proteins were detected among the 28 orfs identifi ...	2007	17629557
gas chromatographic-mass spectrometric study of the degradation of phenolic compounds in wastewater olive oil by azotobacter chroococcum.	compounds present in wastewater olive oil (wwoo) which can be used in metabolic pathways of azotobacter chroococcum (a. chroococcum) have been investigated. some compounds such as syringic acid, p-coumaric acid and syringaldehyde do not favour microorganism growing up. however, it has been shown that in batch culture, polyphenolic compounds (pcs) such as protocatetic acid and p-hydroxybenzoic acid do facilitate the growing up of microorganism. what is more, the maximum concentration in which bac ...	2008	17624767
restoration of fly ash dump through biological interventions.	field experiment on 10 ha area of fly ash dump was conducted to restore and revegetate it using biological interventions, which involves use of organic amendment, selection of suitable plant species along with specialized nitrogen fixing strains of biofertilizer. the results of the study indicated that amendment with farm yard manure at 50 t/ha improved the physical properties of fly ash such as maximum water holding capacity from 40.0 to 62.42% while porosity improved from 56.78 to 58.45%. the ...	2008	17624598
alkyne substrate interaction within the nitrogenase mofe protein.	nitrogenase catalyzes the biological reduction of n(2) to ammonia (nitrogen fixation), as well as the two-electron reduction of the non-physiological alkyne substrate acetylene (hc triple bond ch). a complex metallo-organic species called femo-cofactor provides the site of substrate reduction within the mofe protein, but exactly where and how substrates interact with femo-cofactor remains unknown. recent results have shown that the mofe protein alpha-70(val) residue, whose side chain approaches ...	2007	17610955
alterations in seedling vigour and antioxidant enzyme activities in catharanthus roseus under seed priming with native diazotrophs.	an experiment was conducted on catharanthus roseus to study the effect of seed treatments with native diazotrophs on its seedling growth and antioxidant enzyme activities. the treatments had significant influence on various seedling parameters. there is no significant influence on dry matter production with the diazotrophs, azospirillum and azotobacter. however, the vital seedling parameters such as germination percentage and vigour index were improved. azotobacter treatment influenced maximum o ...	2007	17610323
the oxygen transfer rate influences the molecular mass of the alginate produced by azotobacter vinelandii.	the influence of oxygen transfer rate (otr) on the molecular mass of alginate was studied. in batch cultures without dissolved oxygen tension (dot) control and at different agitation rates, the dot was nearly zero and the otr was constant during biomass growth, hence the cultures were oxygen-limited. the otr reached different maximum levels (otr(max)) and enabled to establish various relative respiration rates. overall, the findings showed that otr influences alginate molecular mass. the mean mo ...	2007	17598106
[biotechnology].		2006	17578084
production of natural fiber reinforced thermoplastic composites through the use of polyhydroxybutyrate-rich biomass.	previous research has demonstrated that production of natural fiber reinforced thermoplastic composites (nfrtcs) utilizing bacterially-derived pure polyhydroxybutyrate (phb) does not yield a product that is cost competitive with synthetic plastic-based nfrtcs. moreover, the commercial production of pure phb is not without environmental impacts. to address these issues, we integrated unpurified phb in nfrtc construction, thereby eliminating a significant energy and cost sink (ca. 30-40%) while co ...	2008	17574844
e1 component of pyruvate dehydrogenase complex does not regulate the expression of nadph-ferredoxin reductase in azotobacter vinelandii.	in azotobacter vinelandii, the e1 component of pyruvate dehydrogenase complex (pdhe1) is proposed to be a key regulatory protein in an oxidative stress management system that responds to superoxide. this proposal was tested by constructing an a. vinelandii mutant that had a disruption of acee gene encoding pdhe1. this mutant exhibited wild-type exponential growth and a normal response to oxidative stress induced by paraquat. electrophoretic mobility-shift assays revealed that a protein previousl ...	2007	17573932
conformational differences between azotobacter vinelandii nitrogenase mofe proteins as studied by small-angle x-ray scattering.	the nitrogenase mofe protein is a heterotetramer containing two unique high-nuclearity metalloclusters, femoco and the p-cluster. femoco is assembled outside the mofe protein, whereas the p-cluster is assembled directly on the mofe protein polypeptides. mofe proteins isolated from different genetic backgrounds have been analyzed using biochemical and spectroscopic techniques in attempting to elucidate the pathway of p-cluster biosynthesis. the deltanifh mofe protein is less stable than other mof ...	2007	17567155
expression, purification, crystallization and preliminary x-ray analysis of pseudomonas fluorescens algk.	algk is an outer-membrane lipoprotein involved in the biosynthesis of alginate in pseudomonads and azotobacter vinelandii. a recombinant form of pseudomonas fluorescens algk with a c-terminal polyhistidine affinity tag has been expressed and purified from the periplasm of escherichia coli cells and diffraction-quality crystals of algk have been grown using the hanging-drop vapour-diffusion method. the crystals grow as flat plates with unit-cell parameters a = 79.09, b = 107.85, c = 119.15 a, bet ...	2007	17565185
p-cluster maturation on nitrogenase mofe protein.	biosynthesis of nitrogenase p-cluster has attracted considerable attention because it is biologically important and chemically unprecedented. previous studies suggest that p-cluster is formed from a precursor consisting of paired [4fe-4s]-like clusters and that p-cluster is assembled stepwise on mofe protein, i.e., one cluster is assembled before the other. here, we specifically tackle the assembly of the second p-cluster by combined biochemical and spectroscopic approaches. by using a p-cluster ...	2007	17563349
studies on intracellular degradation of polyhydroxyalkanoic acid-polyethylene glycol copolymer accumulated by azotobacter chroococcum mal-201.	azotobacter chroococcum mal-201 accumulates poly(3-hydroxybutyric acid) [phb] when grown in glucose containing nitrogen-free stockdale medium. the same medium supplemented with valerate alone and valerate plus polyethylene glycol (peg) leads to the accumulation of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) [phbv] and peg containing phbv-peg polymers, respectively. the intracellular degradation of these polymers as studied in carbon-free stockdale medium showed a rapid degradation of phb follow ...	2007	17543409
molecular insights into nitrogenase femoco insertion--the role of his 274 and his 451 of mofe protein alpha subunit.	the final step of femo cofactor (femoco) assembly involves the insertion of femoco into its binding site in the molybdenum-iron (mofe) protein of nitrogenase. here we examine the role of his alpha274 and his alpha451 of azotobacter vinelandii mofe protein in this process. our results from combined metal, activity, epr, stability and insertion analyses show that mutations of his alpha274 and/or his alpha451, two of the histidines that belong to a so-called his triad, to small uncharged ala specif ...	2007	17521738
in vitro activation of apo-aconitase using a [4fe-4s] cluster-loaded form of the iscu [fe-s] cluster scaffolding protein.	genetic experiments have established that iscu is involved in maturation of [fe-s] proteins that require either [2fe-2s] or [4fe-4s] clusters for their biological activities. biochemical studies have also shown that one [2fe-2s] cluster can be assembled in vitro within each subunit of the iscu homodimer and that these clusters can be reductively coupled to form a single [4fe-4s] cluster. in the present work, it is shown that the [4fe-4s] cluster-loaded form of a. vinelandii iscu, but not the [2f ...	2007	17506526
[change of the wheat lectin activity and degree of its interaction with different components of compositions of lectin nature].	the wheat lectin hemagglutination activity and degree of its interaction with the bacterium azotobacter chroococcum t79 and aminosaccharide n-acetyl-d-glucosamin hapten of wheat lectin was studied in laboratory experiments with the purpose of creation of biologic activity compositions of lectin nature for plant growing. it was shown that plant-bacterial compositions encloses the "bacteria+lectin" complex, free lectin and bacterial cells. the addition of aminosaccharide n-acetyl-d-glucosamin to w ...	2006	17494326
growth of jatropha curcas on heavy metal contaminated soil amended with industrial wastes and azotobacter. a greenhouse study.	the aims of the study were to evaluate the effect of organic wastes (biosludge and dairy sludge) and biofertilizer (azotobacter chroococcum) on the planting conditions of jatropha curcas in metal contaminated soils. results showed that the plants survival rate in heavy metal contaminated soil increased with addition of amendments. treatment t6 (heavy metal contaminated soils+dairy sludge+biofertilizer) observed to be the best treatment for growth (height and biomass) as compared with the treatme ...	2008	17482809
intracellular degradation of poly(3-hydroxybutyric acid) accumulated by azotobacter chroococcum mal-201.	azotobacter chroococcum mal-201 accumulates poly(3-hydroxybutyric acid) [p(3hb)] accounting 69% of cell dry weight (cdw) from glucose during growth in nitrogen-free stockdale medium. degradation of the accumulated polymer by the organism was studied under carbon-free medium following two-step cultivation method. p(3hb) content of cells decreased rapidly from 69% to 4.8% of cdw after 35 h under carbon-deprived condition. autodigestion of p(3hb) was evident from the estimation of intracellular p(3 ...	2005	17405315
specialized lineages of bacterial group ii introns.	the avi.groel intron of azotobacter vinelandii, which interrupts the termination codon of the groel gene, is shown to belong to a monophyletic subset of bacterial group ii introns that share a large insertion at their 5' extremity and a peculiar genetic localization. some of these introns are inserted within, right next to, or very close to, a stop codon while others are located immediately 3' of, or close to, an initiation codon. after subgroup iic introns, which target rho-independent transcri ...	2007	17391829
effects of the deficiency of the rhodanese-like protein rhda in azotobacter vinelandii.	in azotobacter vinelandii the rhda gene codes for a protein (rhda) of the rhodanese-homology superfamily. by combining proteomics, enzymic profiles and ultrastructural observations, the phenotype of an a. vinelandii rhda mutant was analyzed. we found that the a. vinelandii rhda mutant, and not the wild-type strain, accumulated polyhydroxybutyrate. rhda deficiency enhanced the expression of enzymes of the polyhydroxybutyrate biosynthetic operon, and affected the activity of specific tricarboxylic ...	2007	17383639
genes involved in sec-independent membrane targeting of hydrogenase in azotobacter chroococcum.	sec-independent translocation systems have been characterised in escherichia coli and other bacteria and differ from the sec-dependent system by transporting fully folded proteins using the transmembrane proton electrochemical gradient. proteins transported by this system bear a twin-arginine motif (tat) in the n-terminal signal peptide and include several cofactor-containing proteins. azotobacter chroococcum strain (mcd124) has a soluble hydrogenase, which exhibited low o(2)-dependent h(2) upta ...	2007	17368855
role of the h domain of the histidine kinase-like protein nifl in signal transmission.	the nifl protein from azotobacter vinelandii senses both the redox and fixed nitrogen status to regulate nitrogen fixation by controlling the activity of the transcriptional activator nifa. nifl has a domain architecture similar to that of the cytoplasmic histidine protein kinases. it contains two n-terminal pas domains and a c-terminal transmitter region containing a conserved histidine residue (h domain) and a nucleotide binding ghkl domain corresponding to the catalytic core of the histidine ...	2007	17355964
characterization of selected groups of microorganisms occurring in soil rhizosphere and phyllosphere of oats.	studies were carried out on the microflora of phyllosphere and soil rhizosphere of hulled (chwat variety) and naked (akt variety) oats. the material taken for study embraced samples of leaves and soil rhizosphere taken from cultivations differing in extent of nitrogen fertilization. the studies involved determination of total number of aerobic heterotrophic bacteria belonging to the genus pseudomonas and microscopic hyphal fungi. qualitative determinations focused on bacteria belonging to the ge ...	2006	17338275
structure of the redox sensor domain of azotobacter vinelandii nifl at atomic resolution: signaling, dimerization, and mechanism.	nifl is a multidomain sensor protein responsible for the transcriptional regulation of genes involved in response to changes in cellular redox state and adp concentration. cellular redox is monitored by the n-terminal pas domain of nifl which contains an fad cofactor. flavin-based pas domains of this type have also been referred to as lov domains. to explore the mechanism of signal recognition and transduction in nifl, we determined the crystal structure of the fad-bound pas domain of nifl from ...	2007	17319691
physicochemical and biological characteristics of deae-derivatized ps7 biopolymer of beijerinckia indica.	physicochemical and biological characteristics of the exopolysaccharide, ps7, produced from beijerinckia indica were investigated. the ps7 weight fractions of glc and glcua were 0.45 and 0.25, respectively, and the molar ratio of glc:rha:galua was approximately 5:1:1.3. the ps7 was chemically derivatized with diethylaminoethyl chloride-hcl (deae-hcl), and the resulting modified ps7 contained both positive and negative charges. the elemental and ir analyses were conducted to confirm the successfu ...	2007	17316786
molecular and bioengineering strategies to improve alginate and polydydroxyalkanoate production by azotobacter vinelandii.	several aspects of alginate and phb synthesis in azotobacter vinelandii at a molecular level have been elucidated in articles published during the last ten years. it is now clear that alginate and phb synthesis are under a very complex genetic control. genetic modification of a. vinelandii has produced a number of very interesting mutants which have particular traits for alginate production. one of these mutants has been shown to produce the alginate with the highest mean molecular mass so far r ...	2007	17306024
towards biological supramolecular chemistry: a variety of pocket-templated, individual metal oxide cluster nucleations in the cavity of a mo/w-storage protein.		2007	17304608
soil microorganisms in cotton fields sequentially treated with insecticides.	a crop protection system consisting of sequential treatments by six insecticides--dimethoate, monocrotophos, deltamethrin, endosulfan, cypermethrin, and triazophos--at recommended dosages in cotton fields in punjab, india was investigated for its effects on nontarget soil microorganisms and their activities. successive applications of the insecticides caused only short-lived adverse effects on the soil microorganisms. none of the insecticides used had any adverse effects on soil fungi as reflect ...	2008	17298846
connecting nitrogenase intermediates with the kinetic scheme for n2 reduction by a relaxation protocol and identification of the n2 binding state.	a major obstacle to understanding the reduction of n2 to nh3 by nitrogenase has been the impossibility of synchronizing electron delivery to the mofe protein for generation of specific enzymatic intermediates. when an intermediate is trapped without synchronous electron delivery, the number of electrons, n, it has accumulated is unknown. consequently, the intermediate is untethered from kinetic schemes for reduction, which are indexed by n. we show that a trapped intermediate itself provides a " ...	2007	17251348
controlled expression of nif and isc iron-sulfur protein maturation components reveals target specificity and limited functional replacement between the two systems.	the nitrogen-fixing organism azotobacter vinelandii contains at least two systems that catalyze formation of [fe-s] clusters. one of these systems is encoded by nif genes, whose products supply [fe-s] clusters required for maturation of nitrogenase. the other system is encoded by isc genes, whose products are required for maturation of [fe-s] proteins that participate in general metabolic processes. the two systems are similar in that they include an enzyme for the mobilization of sulfur (nifs o ...	2007	17237162
structure-based evaluation of in silico predictions of protein-protein interactions using comparative docking.	due to the limitations in experimental methods for determining binary interactions and structure determination of protein complexes, the need exists for computational models to fill the increasing gap between genome sequence information and protein annotation. here we describe a novel method that uses structural models to reduce a large number of in silico predictions to a high confidence subset that is amenable to experimental validation.	2007	17237047
microscopical investigation of poly(3-hydroxybutyrate) granule formation in azotobacter vinelandii.	poly(3-hydroxybutyrate) (phb) granule formation in azotobacter vinelandii was investigated by laser scanning fluorescence microscopy after staining the cells with nilered and baclight. cells that had been starved for a carbon source for > or =3 days were almost free of phb granules. formation of visible phb granules started within 1-2 h after transfer of the cells to a medium permissive for phb accumulation. fluorescent phb granules at the early stages of formation were exclusively found in the ...	2007	17233718
novel bioconversion of wheat straw to bio-organic fertilizer in a solid-state bioreactor.	in order to increase the eco-efficiency and overall availability of naturally renewable resource, the novel bioconversion of steam-exploded wheat straw to bio-organic fertilizer containing n(2)-fixer, p and k solubilizers was investigated. the conversion was performed in solid-state fermentation (ssf) with periodic air-forced pressure oscillation (papo). the results showed that ssf-papo was competitive with the conventional solid-state fermentation (cssf) in biomass accumulation and wheat straw ...	2007	17225993
micropropagation of photinia employing rhizobacteria to promote root development.	an alternative protocol was developed for in vitro propagation of photinia (photinia x fraseri dress), an ornamental shrub, using the plant growth-promoting rhizobacteria (pgpr) azospirillum brasilense and azotobacter chroococcum during rhizogenesis. shoot tips from four-year-old mature plants, cut in spring and summer, were used as initial explants. they were cultured on murashige-skoog (ms) medium with gamborg's vitamins, n(6)-benzyladenine (ba: 11.1 microm) and gibberellic acid (ga(3): 1.3 mi ...	2007	17205338
molecular insights into nitrogenase femo cofactor insertion: the role of his 362 of the mofe protein alpha subunit in femo cofactor incorporation.	the assembly of the complex iron-molybdenum cofactor (femoco) of nitrogenase molybdenum-iron (mofe) protein has served as one of the central topics in the field of bioinorganic chemistry for decades. here we examine the role of a mofe protein residue (his alpha362) in femoco insertion, the final step of femoco biosynthesis where femoco is incorporated into its binding site in the mofe protein. our data from combined metal, activity and electron paramagnetic resonance analyses show that mutations ...	2007	17203313
tn10 mutagenesis in azotobacter vinelandii.	the tetracycline-resistant transposon tn10 and its "high-hopper" derivative tn10hh104 were introduced into the azotobacter vinelandii genome using suicide conjugative plasmids derived from prk2013. several types of mutants induced by either of these elements are described. nif- mutants (deficient in nitrogen fixation) were easily isolated, whereas the isolation of other mutant types (auxotrophs, sugar non-users) required special selection conditions. the characterization of the mutations as tran ...	1987	17191343