Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.7.1.2 (nitrate reductase)
 3,861 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The present study confirms that chlorate is toxic only to brown algae and not to species of other ecologically relevant taxa. The brown alga Ectocarpus variabilis exhibited a LOEC of 0.005 mM (0.4 mg ClO3-/liter) and an LC50 of 0.012 mM, when cultured with nitrate as a sole source of nitrogen. The toxicity to species other than brown algae as measured in growth inhibition tests ranged from 0.75 mM (96-h NOEC) for Selenastrum capricornutum to > or = 7.48 mM (48-h NOEC) for the fungus Trichoderma hamatum. The nitrogen source, nitrate or ammonium, did not significantly influence the toxicity to the nonsensitive species. The tests on brown algae found that as compared with ammonium, the toxicity to nitrate-grown cultures is higher by a factor of about 10. This confirms the hypothesis that nitrate reductase is involved in the toxic effects of chlorate on brown algae. Chlorite, tested as a potential toxic metabolite of chlorate, demonstrated high toxicity to many of the taxa tested and only low toxicity to E. variabilis. It may be concluded that brown algae are exceptionally sensitive to chlorate. It may also be concluded that various nitrogen sources could not induce toxicity in nonsensitive species. From these experiments no conclusions could be drawn as to the potential role of chlorite in chlorate toxicity. Furthermore it may be concluded that E. variabilis is a suitable laboratory test species for further investigations into the mechanism of chlorate toxicity to brown algae.
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PMID:Toxicity of chlorate and chlorite to selected species of algae, bacteria, and fungi. 967 83

A Gram-negative, facultatively anaerobic, rod-shaped, dissimilatory chlorate-reducing bacterium, strain AW-1(T), was isolated from biomass of an anaerobic chlorate-reducing bioreactor. Phylogenetic analysis of the 16S rDNA sequence showed 100% sequence similarity to Pseudomonas stutzeri DSM 50227 and 98.6% sequence similarity to the type strain of P. stutzeri (DSM 5190(T)). The species P. stutzeri possesses a high degree of genotypic and phenotypic heterogeneity. Therefore, eight genomic groups, termed genomovars, have been proposed based upon deltaTm values, which were used to evaluate the quality of the pairing within heteroduplexes formed by DNA-DNA hybridization. In this study, DNA-DNA hybridization between strain AW-1(T) and P. stutzeri strains DSM 50227 and DSM 5190(T) revealed respectively 80.5 and 56.5% similarity. DNA-DNA hybridization between P. stutzeri strains DSM 50227 and DSM 5190(T) revealed 48.4% similarity. DNA-DNA hybridization indicated that strain AW-1(T) is not related at the species level to the type strain of P. stutzeri. However, strain AW-1(T) and P. stutzeri DSM 50227 are related at the species level. The physiological and biochemical properties of strain AW-1(T) and the two P. stutzeri strains were compared. A common characteristic of P. stutzeri strains is the ability to denitrify. However, in growth experiments, strain AW-1(T) could use only chlorate or oxygen as an electron acceptor and not nitrate, perchlorate or bromate. Strain AW-1(T) is the first chlorate-reducing bacterium described that does not possess another oxyanion-reduction pathway. Cell extracts of strain AW-1(T) showed chlorate and bromate reductase activities but not nitrate reductase activity. P. stutzeri strains DSM 50227 and DSM 5190(T) could use nitrate or oxygen as an electron acceptor, but not chlorate. Chlorate reductase activity, in addition to nitrate reductase activity, was detected in cell extracts of both P. stutzeri strains. Chlorite dismutase activity was absent in extracts of both P. stutzeri strains but was present in extracts of strain AW-1(T). Based on the hybridization experiments and the physiological and biochemical data, it is proposed that strain AW-1(T) be classified as a novel species of Pseudomonas, Pseudomonas chloritidismutans sp. nov. The type strain is strain AW-1(T) (= DSM 13592(T) = ATCC BAA-443(T)).
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PMID:Pseudomonas chloritidismutans sp. nov., a non-denitrifying, chlorate-reducing bacterium. 1250 87

The use of chlorate as a selective inhibitor of dissimilative nitrate reduction was studied using pure cultures of Comamonas testosteroni (a denitrifier) and Klebsiella pneumoniae (a nitrate-ammonifier) isolated from estuarine sediment, and in sediment slurry. Pure culture experiments demonstrated that chlorate selectively inhibited membrane-bound nitrate reductase (Nar) activity, probably by blocking nitrate transporters (NarK). Sediment slurry experiments showed that chlorate inhibited nitrate reduction and N(2)O formation, but did not inhibit nitrite reduction and its N(2)O formation, indicating that chlorate selectively inhibited only the first step of nitrate reduction. Chlorite chemically oxidized nitrite to nitrate and could not be used as a selective inhibitor of nitrite metabolism, although chlorite apparently selectively inhibited formation of N(2)O from nitrite. Chlorate can be used as a specific inhibitor to distinguish between nitrate reduction by Nap or Nar in natural communities of microorganisms.
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PMID:Use of chlorate as a selective inhibitor to distinguish membrane-bound nitrate reductase (Nar) and periplasmic nitrate reductase (Nap) of dissimilative nitrate reducing bacteria in sediment. 1971 7