共查询到20条相似文献,搜索用时 15 毫秒
1.
The perchlorate (ClO4−)-respiring organism, strain perc1ace, can grow using nitrate (NO3−) as a terminal electron acceptor. In resting cell suspensions, NO3− grown cells reduced ClO4−, and ClO4− grown cells reduced NO3−. Activity assays showed that nitrate reductase (NR) activity was 1.31 μmol min−1 (mg protein)−1 in ClO4− grown cells, and perchlorate reductase (PR) activity was 4.24 μmol min−1 (mg protein)−1 in NO3− grown cells. PR activity was detected within the periplasmic space, with activities as high as 14 μmol min−1 (mg protein)−1. The NR had a pH optimum of 9.0 while the PR had an optimum of 8.0. This study suggests that separate terminal reductases are present in strain perclace to reduce NO3− and ClO4−. 相似文献
2.
Nitrate-limited batch cultures, incorporating 20 different fermentation substrates and inoculated with human faeces, mainly selected for the growth of enterobacteria. The microbial diversity involved was determined by a combination of phenotypic and genotypic procedures. Continuous culture with lactate as the sole electron donor selected for similar micro-organisms, but when antibiotics were incorporated to inhibit Escherichia coli and lactate was replaced with choline, there was a wider microbial diversity recovered. Clostridium ramosum and Bacteroides vulgatus were then isolated as well as enterobacteriaceae. 相似文献
3.
Kassem Alef 《FEMS microbiology letters》1987,48(1-2):11-14
Abstract The interaction between nitrate- and dimethyl-sulphoxide (DMSO)-reducing pathways was demonstrated in intact cells of Rhodobacter capsulatus AD2 removed from cultures grown under different conditions. The results provide evidence of competition between the DMSO and nitrate reductases for a common electron pool. Furthermore, strong inhibition was observed of the anaerobic dark DMSO-dependent growth of R. capsulatus by nitrate in the growth medium. This phenomenon is also discussed. 相似文献
4.
A miniaturized nitrate reduction test (MNRT) for oral bacteria was developed and its reliability compared with a conventional nitrate reduction test (CNRT). In the MNRT 100 μl aliquots of freshly grown heavy suspension of various oral bacterial species, in physiological saline, were added to equal volumes of 0.1% filter-sterilized KNO3 solution in distilled water in wells of transparent plastic plates. Duplicate plates were incubated aerobically or anaerobically at 35°C for 12–15 h. At the end of the incubation period the test was performed by adding either a trace amount of a non-liquid reagent (mixture of l-(+)-tartaric acid, sulfanilic acid and 1-naphthylenediamine dihydrochloride, 10:1:1, wt/wt) or conventional liquid reagents A and B (sulfanilic acid and N,N-dimethyl-1-naphthylamine). In the conventional nitrate reduction test (CNRT), tubes of a basal anaerobic broth were inoculated with the same bacterial species used for MNRT, and the nitrate reduction tests performed after anaerobic incubation of the cultures for 4–6 days. Several hundred anaerobic and facultative bacterial isolates belonging to genera Veillonella, Bacteroides, Fusobacterium, Selenomonas, Actinomyces and Capnocytophaga were characterized by MNRT and CNRT. Analysis of the data showed that MNRT and CNRT systems were comparable. In the MNRT system Veillonella parvula and Selenomonas sputigena were capable of reducing nitrate only under anaerobic conditions. Actinomycetes reduced the nitrates under aerobic and anaerobic conditions, while all black-pigmented Bacteroides, Fusobacterium and Capnocytophaga species did not reduce nitrate. These findings suggest that the MNRT is reliable, rapid and may be conveniently used in clinical or research laboratories with a heavy microbiological work load. 相似文献
5.
Abstract The electron flow to the dissimilatory nitrate reductase (NRII), and dimethylsulphoxide (DMSO) oxidoreductase in Rhodopseudomonas capsulata strains was studied. Our results support the view that DMSO reduction, like dissimilatory nitrate reduction was linked to the electron transfer chain and probably coupled to energy conservation. 相似文献
6.
In the presence of purified nitrate reductase (NR) and 1 mM NADH, illuminated pea chloroplasts catalysed reduction of NO3? to NH3 with the concomitant evolution of O2. The rates were slightly less than those for reduction of NO2? to NH3 and O2, evolution by chloroplasts in the absence of NR and NADH (ca 6 μg atoms N/mg Chl/hr). Illuminated chloroplasts quantitatively reduced 0.2 mM oxaloacetate (OAA) to malate. In the presence of an extrachloroplast malate-oxidizing system comprised of NAD-specific malate dehydrogenase (NAD-MDH), NAD, NR and NO3?, illuminated chloroplasts supported OAA-dependent reduction of NO3? to NH3 with the evolution of O2. The reaction did not proceed in the absence of any of these supplements or in the dark but malate could replace OAA. The results are consistent with the reduction of NO3?by reducing equivalents from H2O involving a malate/OAA shuttle. The ratios for O2, evolved: C4-acid supplied and N reduced: C4-acid supplied in certain experiments imply recycling of the C4-acids. 相似文献
7.
J. L. WRAY 《Plant, cell & environment》1988,11(5):369-382
Abstract. The application of molecular approaches such as mutant analysis and recombinant DNA technology, in conjunction with immunology, are set to revolutionize our understanding of the nitrate assimilation pathway. Mutant analysis has already led to the identification of genetic loci encoding a functional nitrate reduction step and is expected to lead ultimately to the identification of genes encoding nitrate uptake and nitrite reduction. Of particular significance would be identification of genes whose products contribute to regulatory networks controlling nitrogen metabolism. Recombinant DNA techniques are particularly powerful and have already allowed the molecular cloning of the genes encoding the apoprotein of nitrate reductase and nitrite reductase. These successes allow for the first lime the possibility to study directly the role of environmental factors such as type of nitrogen source (NO3 − or NH4 + ) available to the plant, light, temperature water potential and CO2 and O2 tensions on nitrate assimilation gene expression and its regulation at the molecular level. This is an important advance since our current understanding of the regulation of nitrate assimilation is based largely on changes of activity of the component steps. The availability of mutants, cloned genes, and gene transfer systems will permit attempts to manipulate the nitrate assimilation pathway. 相似文献
8.
Summary Reported non-stoichiometry in the reduction of nitrate to nitrite was investigated in leaves ofZea mays L.. The nitrogen balance sheet forin vitro nitrate assimilation was influenced by enzyme protectants in the extraction media and by the method employed to terminate the reaction. A number of limitations were found in the generally acceptedin vitro nitrate reductase assay, in particular the presence of endogenous components which interfered with the assay of nitrite were considered. A stoichiometric balance for thein vitro reduction of nitrate to nitrite was obtained when interfering factors were minimized. The absence of back reactions from ammonia in the assay was confirmed. 相似文献
9.
Potter LC Millington PD Thomas GH Rothery RA Giordano G Cole JA 《FEMS microbiology letters》2000,185(1):51-57
Escherichia coli strain LCB2048 is a double mutant defective in the synthesis of the two membrane-associated nitrate reductases A and Z. This strain can grow anaerobically on a non-fermentable carbon source, glycerol, in the presence of nitrate even in media supplemented with high concentrations of tungstate. This growth was totally dependent upon a highly active, periplasmic nitrate reductase (Nap). Due to the presence of a previously unreported narL mutation, synthesis of the periplasmic nitrate reductase by this strain was induced during anaerobic growth by nitrate. We have also demonstrated that methyl viologen is an ineffective electron donor to Nap: its use leads to an underestimation of the contribution of Nap activity to the rate of nitrate reduction in vivo. 相似文献
10.
11.
A freshwater sediment from a ditch of a peat grassland near Zegveld (Province of Utrecht, The Netherlands) was investigated for its potential methanogenic and syntrophic activity and the influence of sulfate and nitrate on these potential activities. Methanogenesis started after a 10 days lagphase. After 35–40 days aceticlastic methanogens were sufficiently enriched to cause a net decrease of acetate. In the presence of sulfate methane formation was only slightly affected. The addition of nitrate led to an outcompetion of aceticlastic methanogens by nitrate reducers. When inorganic electron acceptors were absent, substrates like propionate and butyrate were converted by syntrophic methanogenic consortia. Addition of inorganic electron acceptors resulted in an outcompetition of the syntrophic propionate and butyrate degrading consortia by the sulfate and nitrate reducers. 相似文献
12.
Wheat leaves exposed to 710 nm monochromatic light, when only photosystem 1 operates, reduced small but significant amount
of nitrate to nitrite. This could be due to partial inhibition of mitochondrial oxidation of NADH, brought about by cyclic
photo-phosphorylation. Under dark aerobic conditions, citric acid cycle intermediates only slightly stimulated nitrate reduction.
Under dark anaerobic conditions, when maximum reduction of nitrate occurred, the time course showed a 1:1 stoichiometry between
nitrite and CO2. It is suggested that for maximum reduction of nitrate under physiological conditions, CO2 fixation and export of ATP via triose phosphate shuttle is essential. 相似文献
13.
Hans J. Brons Wilfred R. Hagen Alexander J. B. Zehnder 《Archives of microbiology》1991,155(4):341-347
l-Lactate-driven ferric and nitrate reduction was studied in Escherichia coli E4. Ferric iron reduction activity in E. coli E4 was found to be constitutive. Contrary to nitrate, ferric iron could not be used as electron acceptor for growth. Ferric iron reductase activity of 9 nmol Fe2+ mg-1 protein min-1 could not be inhibited by inhibitors for the respiratory chain, like Rotenone, quinacrine, Actinomycin A, or potassium cyanide. Active cells and l-lactate-driven nitrate respiration in E. coli E4 leading to the production of nitrite, was reduced to about 20% of its maximum activity with 5 mM ferric iron, or to about 50% in presence of 5 mM ferrous iron. The inhibition was caused by nitric oxide formed by a purely chemical reduction of nitrite by ferrous iron. Nitric oxide was further chemically reduced by ferrous iron to nitrous oxide. With electron paramagnetic resonance spectroscopy, the presence of a free [Fe2+-NO] complex was shown. In presence of ferrous or ferric iron and l-lactate, nitrate was anaerobically converted to nitric oxide and nitrous oxide by the combined action of E. coli E4 and chemical reduction reactions (chemodenitrification). 相似文献
14.
Activities of nitrate reduction enzymes, nitrate reductase activity (NRA) and nitrite reductase activity (NiRA) from roots and nodules of 5 mutant genotypes and one commercial cultivar (Alameda) of faba bean ( Vicia faba L. var. minor) grown in the presence of N2 alone or with additional NO− 3 in the medium have been studied. A naturally occurring mutant (VFM109) with impaired ability to reduce nitrate in its nodules is described. All the other cultivars of V. faba showed nodule NRA, although the range was very wide, from almost negligible (VFM72) up to 2 μmol h−1 (g FW)−1 . This activity was entirely of plant origin. Root NRA also ranged widely accross cultivars. However, the level of activity expressed as well as the response of NRA to nitrate followed a pattern opposite to that observed in nodules. Roots and nodules of all cultivars showed very high rates of NiRA, respectively 50 and 150-fold higher than NRA, thus precluding accumulation of nitrite in these tissues. Root enzymes were significantly stimulated by nitrate while negative (NRA) or little effect (NiRA) was found for nodules. Nitrate and nitrite reduction are carried out by inducible enzymes in roots of V. faba and by constitutive enzymes in nodules, indicating that there may be different forms of these enzymes in each tissue. Differences in the plant genotype were a major cause of the variability in nitrate and nitrite reduction by nodulated root systems of V. faba . 相似文献
15.
Ammonia at concentrations above 1×10-5 M inhibits uptake of nitrate in the nitrogen-fixing blue-green alga, Anabaena cylindrica. This inhibition takes place both in the light and in the dark. The rate of nitrate uptake is stimulated by light. Addition of relatively high concentrations of nitrate (1–10 mM) reversibly inhibits ammonia uptake. FCCP, an uncoupler of phosphorylation, inhibits both nitrate and ammonia uptake. Ammonia may inhibit nitrate uptake by reducing the supply of energy (ATP) for active nitrate transport.Abbreviations FCCP
carbonyl cyanide p-trifluoromethoxy-phenylhydrazone
- CCCP
carbonyl cyanide m-chlorophenyl-hydrazone 相似文献
16.
Batch cultures of Chlorella fusca excreted nitrite into the medium if gassed with air (0.03% CO2), but they did not if supplied with air containing 5% CO2. After a change from high to low CO2 concentration in the gas stream, nitrite excretion started immediately. After an increase in CO2 concentration to 5%, nitrite uptake started within only 30 min. Changes of in-vitro activities of nitrate reductase, nitrite reductase and glutamine synthetase did not correspond to changes of nitrite concentration in the medium and therefore could not explain these observations. A nitrite-binding site, whose activity corresponded with both nitrite excretion and uptake, was detected at the chloroplast envelope. From these data an additional regulatory step in the assimilatory nitrate-reduction sequence is suggested. This includes an envelopeprotein fraction probably regulating the availability of nitrite within the chloroplast.Abbreviations FMN
riboflavin 5-phosphate
- GS
glutamine synthetase
- NIR
nitrite reductase
- NR
nitrate reductase 相似文献
17.
Beggiatoa alba B18LD utilizes both nitrate and nitrite as sole nitrogen sources, although nitrite was toxic above 1 mM.B. alba coupledin vivo acetate oxidation, but not sulfide oxidation, with nitrate and nitrite reduction.B. alba could not, however, grow anaerobically with nitrate as the sole electron acceptor. Furthermore, the incorporation of acetate into macromolecules under anaerobic conditions with nitrate as the sole electron acceptor was less 10% of the incorporation with oxygen as the electron acceptor. The product of nitrate reduction byB. alba was ammonia; N2 or N2O were not produced. The nitrate reductase activity inB. alba was soluble and it utilized reduced flavins or methyl viologen and dithionite as electron donors. Pyrimidine nucleotides were not used as in vitro electron donors, either alone or with flavins in coupled assays. TheB. alba nitrate reductase activity was competitively inhibited with chlorate and was only mildly inhibited by azide and cyanide. Nitrate was not required for induction of theB. alba nitrate reductase, and neither oxygen nor ammonia repressed its activity. Thus,B. alba nitrate reductase appears to be an assimilatory nitrate reductase with unusual regulatory properties.Non-standard abbreviations MV
Methyl viologen
- DT
dithionite
- GS
glutamine synthetase
- GOGAT
glutamine 2-oxoglutarate aminotransferase
- PPO
2-diphenyloxazole
- POPOP
1,4-(bis)-[2-(5-phenyloxazolyl)] benzene
- TCA
trichloroacetic acid
- CCCP
carbonylcyanidem-chlorophenylhydrazone
- FCCP
carbonylcyanidep-trifluoromethoxyphenylhydrazone
- TTFA
thenoyltrifluoroacetone
- PHEN
1,10-phenanthroline
- HOQNO
2-heptyl 4-hydroxyquinoline-n-oxide
- 8HQ
8-hydroxyquinoline 相似文献
18.
Konovalova V Nigmatullin R Dmytrenko G Pobigay G 《Bioprocess and biosystems engineering》2008,31(6):647-653
Sequential reduction of chromate and nitrate, two competitive electron acceptors, has been demonstrated for strains of Pseudomonas genus for both planktonic cells and cells immobilised in agar layers on the surface of synthetic membrane. Denitrification occurs practically after chromate depletion. This order of reduction process is consistent with redox potentials of the respective reactions. In a membrane bioreactor, competitive inhibition results in nitrate transfer through the membrane without transformation. Thus the receiving phase is contaminated with nitrate. To address this problem, a membrane has been used for spatial sequencing of chromate and nitrate reduction. Bacterial cells were immobilised in two layers with each layer placed on opposing sides of the membrane. By this means, chromate reduction is localised into the layer contacting the feed phase while nitrate reduction occurs in the layer facing the receiving phase. As a result, only traces of the pollutants are detected in the receiving phase. 相似文献
19.
Francisco Martínez Murillo Theresa Gugliuzza John Senko Partha Basu J. F. Stolz 《Archives of microbiology》1999,172(5):313-320
Nitrate reduction in the dissimilatory iron-reducing bacterium Geobacter metallireducens was investigated. Nitrate reductase and nitrite reductase activities in nitrate-grown cells were detected only in the membrane
fraction. The apparent K
m values for nitrate and nitrite were determined to be 32 and 10 μM, respectively. Growth on nitrate was not inhibited by either
tungstate or molybdate at concentrations of 1 mM or less, but was inhibited by both at 10 and 20 mM. Nitrate and nitrite reductase
activity in the membrane fraction was not, however, affected by dialysis with 20 mM tungstate. An enzyme complex that exhibited
both nitrate and nitrite reductase activity was solubilized from membrane fractions with CHAPS and was partially purified
by preparative gel electrophoresis. It was found to be composed of four different polypeptides with molecular masses of 62,
52, 36, and 16 kDa. The 62-kDa polypeptide [a low-midpoint potential (–207 mV), multiheme cytochrome c] exhibited nitrite reductase activity under denaturing conditions. No molybdenum was detected in the complex by plasma-emission
mass spectrometry.
Received: 26 March 1999 / Accepted: 16 August 1999 相似文献
20.