Showing papers on "Nitrite published in 1985"

Mammalian nitrate biosynthesis: mouse macrophages produce nitrite and nitrate in response to Escherichia coli lipopolysaccharide.

Abstract: Escherichia coli lipopolysaccharide (LPS)-induced nitrate biosynthesis was studied in LPS-sensitive C3H/He and LPS-resistant C3H/HeJ mice. Intraperitoneal injection of 15 micrograms of LPS led to a temporary 5- to 6-fold increase in blood nitrate concentration in the C3H/He strain. Levels of nitrate excreted in the urine were also increased. In contrast, no increase was observed in the C3H/HeJ strain with LPS injections up to 175 micrograms. Furthermore, thioglycolate-elicited peritoneal macrophages from C3H/He, but not from C3H/HeJ mice, produced nitrite (60%) and nitrate (40%) when cultured with LPS (10 micrograms/ml). T-lymphocyte addition/depletion experiments showed the presence of T cells enhanced this response. However, LPS did not cause nitrite or nitrate production in cultures of spleen lymphocytes from either strain. LPS-induced nitrate synthesis was also observed with nude mice and CBA/N mice, indicating that neither functional T lymphocytes nor LPS-responsive B lymphocytes were required for the response in vivo. This was consistent with the in vitro results showing macrophages alone were competent. Mycobacterium bovis infection of C3H/He and C3H/HeJ mice resulted in a large increase in nitrate production over the course of the infection for both strains, suggesting T-lymphocyte-mediated activation of macrophages as a potent stimulus for nitrate biosynthesis. The synthesis of nitrite is significant in that it can directly participate in the endogenous formation of nitrosamines and may also be involved in some aspect of the chemistry of cytotoxicity.

15N Kinetic Analysis of N2O Production by Nitrosomonas europaea: an Examination of Nitrifier Denitrification

Abstract: A series of 15N isotope tracer experiments showed that Nitrosomonas europaea produces nitrous oxide only under oxygen-limiting conditions and that the labeled N from nitrite, but not nitrate, is incorporated into nitrous oxide, indicating the presence of the “denitrifying enzyme” nitrite reductase. A kinetic analysis of the m/z 44, 45, and 46 nitrous oxide produced by washed cell suspensions of N. europaea when incubated with 4 mM ammonium (99% 14N) and 0.4 mM nitrite (99% 15N) was performed. No labeled nitrite was reduced to ammonium. All labeled material added was accounted for as either nitrite or nitrous oxide. The hypothesis that nitrous oxide is produced directly from nitrification was rejected since (i) it does not allow for the large amounts of double-labeled (m/z 46) nitrous oxide observed; (ii) the observed patterns of m/z 44, 45, and 46 nitrous oxide were completely consistent with a kinetic analysis based on denitrification as the sole mechanism of nitrous oxide production but not with a kinetic analysis based on both mechanisms; (iii) the asymptotic ratio of m/z 45 to m/z 46 nitrous oxide was consistent with denitrification kinetics but inconsistent with nitrification kinetics, which predicted no limit to m/z 45 production. It is concluded that N. europaea is a denitrifier which, under conditions of oxygen stress, uses nitrite as a terminal electron acceptor and produces nitrous oxide.

Nitrate Inhibition of Legume Nodule Growth and Activity: I. Long Term Studies with a Continuous Supply of Nitrate

Abstract: The synthesis and accumulation of nitrite has been suggested as a causative factor in the inhibition of legume nodules supplied with nitrate. Plants were grown in sand culture with a moderate level of nitrate (2.1 to 6.4 millimolar) supplied continuously from seed germination to 30 to 50 days after planting. In a comparison of nitrate treatments, a highly significant negative correlation between nitrite concentration in soybean (Glycine max [L.] Merr.) nodules and nodule fresh weight per shoot dry weight was found even when bacteroids lacked nitrate reductase (NR). However, in a comparison of two Rhizobium japonicum strains, there was only 12% as much nitrite in nodules formed by NR−R. japonicum as in nodules formed by NR+R. japonicum, and growth and acetylene reduction activity of both types of nodules was about equally inhibited. In a comparison of eight other NR+ and NR−R. japonicum strains, and a comparison of G. max, Phaseolus vulgaris, and Pisum sativum, the concentration of nitrite in nodules was unrelated to nodule weight per plant or to specific acetylene reduction activity. The very small concentration of nitrite found in P. vulgaris nodules (0.05 micrograms NO2−-N per gram fresh weight) was probably below that required for the inhibition of nitrogenase based on published in vitro experiments, and yet the specific acetylene reduction activity was inhibited 83% by nitrate. The overall results do not support the idea that nitrite plays a role in the inhibition of nodule growth and nitrogenase activity by nitrate.

The influence of nitrate concentration upon the end-products of nitrate dissimilation by bacteria in anaerobic salt marsh sediment

Abstract: Experiments were carried out with slurries of saltmarsh sediment to which varying concentrations of nitrate were added. The acetylene blocking technique was used to measure denitrification by accumulation of nitrous oxide, while reduction of nitrate to nitrite and ammonium was also measured. There was good recovery of reduced nitrate and at the smallest concentration of nitrate used (250 μM) there was approximately equal reduction to either ammonium or nitrous oxide (denitrification). Nitrite was only a minor end-product of nitrate reduction. As the nitrate concentration was increased the proportion of the nitrate which was denitrified to nitrous oxide increased, to 83% at the greatest nitrate concentration used (2 mM), while reduction to ammonium correspondingly decreased. This change was attributed either to a greater competitiveness by the denitrifiers for nitrate as the ratio of electron donor to electron acceptor decreased; or to the increased production of nitrite rather than ammonium by fermentative bacteria under high nitrate, the nitrite then being reduced to nitrous oxide by denitrifying bacteria.

Evidence from the reaction between trioxodinitrate(II) and nitrogen-15-labeled nitric oxide that trioxodinitrate(II) decomposes into nitrosyl hydride and nitrite in neutral aqueous solution

Abstract: Les produits finaux sont N 2 O et nitrite; leurs rendements supposent que le trioxodinitrate se decompose en nitroxyle et nitrite. La reaction est controlee par la diffusion

Absorption of NOx gases

Abstract: Oxidation of nitric oxide is an important step in NOx absorption. Recent advances namely catalytic oxidation and the use of slrong oxidizing agents have been reviewed. The refinements which have been made in the kinetics of NO oxidation have been discussed. Several liquid phase absorbents have been suggested for the NO removal, particularly for the purpose of pollution abatement. Different models for NO oxidation using nitric acid have been analysed and the limitations of published information have been brought out. Absorption of tetravalent nitrogen oxide (NO2 and N2O4) has received considerable attention. The absorbents include water, nitric and sulfuric acids, sodium hydroxide, sodium sulfite and sodium chlorite. Absorption in water and nitric acid is important in the manufacture of nitric acid. The published information on the mechanism of NO2 and N2O4 absorption in water has been critically analysed. The problem of nitrous acid decomposition has been analysed on the basis of film theory. The predicti...

Nitrate in silage

Abstract: Due to intensive Fertilizer application most silage crops contain appreciable amounts of nitrate. During silage fermentation the nitrate is completely or partially degraded. End-products are ammonia and nitrous oxide with nitrite and nitric oxide occurring as intermediates. Factors that influence nitrate degradation and the levels of end products and intermediates found in silages are reviewed. The role of plant nitrate reductase and of enterobacteria, Clostridia and lactobacilli in nitrate catabolism and the significance for silage quality are discussed. Attention is paid to silo-filler's disease, an illness of farm workers that is caused by inhalation of oxides of nitrogen, and to the occurrence of nitrosamines in silages.

Differentiation of c,d1 cytochrome and copper nitrite reductase production in denitrifiers

Abstract: Gas chromatographic analyses revealed that rates of release of nitrous oxide from nitrite or nitric oxide in extracts of the c , d 1 cytochrome nitrite reductase-producing denitrifiers, Paracoccus denitrificans and Pseudomonas perfectomarina , were unaffected by preincubation with the metal chelator, diethyldithiocarbamate (DDC). In contrast, preincubation with DDC completely inhibited generation of nitrous oxide from nitrite in extracts of copper protein nitrite reductase-producing denitrifiers, “ Achromobacter cycloclastes ” and Rhodopseudomonas sphaeroides forma species denitrificans . Pre-exposure to DDC lessened but did not completely inhibit nitric oxide reduction in extracts of the copper protein nitrite reductase-producing denitrifiers. Proton consumption values resulting from pulsing with nitrite were similarly completely inhibited by preincubation with DDC of extracts of the two copper protein-producing denitrifiers. Uptake values related to pulsing with nitric oxide were also lessened but not completely inhibited by prior exposure to DDC. As anticipated, proton consumption was not affected by preincubation with DDC in extracts of P. denitrificans pulsed with nitrite or nitric oxide. Differential sensitivity of copper protein nitrite reductase activity to DDC could provide the simple assay method needed for determination of the distribution of two types of nitrite reductase producers among populations of denitrifiers in nature.

Molybdate reduction by Escherichia coli K-12 and its chl mutants

Abstract: During anaerobic growth, Escherichia coli can reduce phosphomolybdate. The reduction can also be carried out by washed cells suspended in buffer at pH 5.7. Phosphate, molybdate, glucose, cells, and anaerobic conditions are required. Reduction is inhibited by 200 microM chromate, 290 microM nitrite, 10 mM tungstate, or 20 mM cysteine. Wild-type (chl+) cells are inhibited by addition of 200 microM nitrate, but chlA, chlB, and chlE mutants are not. The inhibition of chl+ cells results from reduction of nitrate to nitrite. This nitrate reduction is not catalyzed by nitrate reductase. Wild-type cells are more sensitive than chl mutants to inhibition by nitrite and cysteine but more resistant to chromate. Pregrowth of chlD cells in 1 mM Na2MoO4 increases their sensitivity to nitrite and cysteine, and pregrowth of chl+ cells in 1 mM Na2MoO4 increases their resistance to these agents. Assays of biotin sulfoxide reductase show that the tightness of the chlD block depends on growth conditions; chlD cells grown aerobically in tryptone broth make about 50% as much active enzyme as chl+ cells, whereas chlD cells grown anaerobically with tryptone plus glucose make less than 10%. The effect of anaerobic pregrowth on the inhibition of molybdate reduction by added nitrate indicates that in vivo nitrate reduction responds to growth conditions in the same manner as biotin sulfoxide reductase does.

Isotopic Fractionation During Reduction of Nitrate and Nitrite by Extracts of Spinach Leaves

Abstract: The isotopic fractionations of nitrogen during the reduction of NO3- and NO2- in a cytosolic fraction and in a chloroplast preparation from spinach (Spinacia oleracea L.) leaves were determined. The reduction of NO3- to NH3 was studied using a reconstituted system containing cytosolic extract and intact chloroplasts, while a chloroplast system was used for NO2- reduction. In the reconstituted systems the ratio of nitrate reductase activity to nitrite reductase activity had a large effect on the relative amounts of NO2- and NH3 formed. Ammonia predominated when the nitrate reductase to nitrite reductase activity ratio was 1 : 5 and this ratio was used in the isotopic fractionation studies. Significant isotopic fractionation of N was observed in the reconstituted system but not in the chloroplast system. This indicates that the observed isotopic fractionation was associated with the reduction of NO3- to NO2- by nitrate reductase. The isotopic fractionation (i.e. δ15Nproduct - δ15Nsubstrate) for this reaction was - 15‰.

Nitrite and nitrous oxide production by Methylosinus trichosporium.

Abstract: Conditions for the production of nitrite and nitrous oxide by an obligate methanotroph, Methylosinus trichosporium (OB 3b), were studied. The rate of nitrite production was correlated with the concentration of ammonia up to 20 mM in the presence of sufficient amounts of oxygen and inversely correlated with the amounts of methane in the system. The rate of nitrous oxide (N2O) production was correlated positively with and the amount of nitrite produced and inversely with the oxygen concentration in the system. Nitrite started to disappear when either oxygen or methane or both were depleted, but only a part of the loss could be accounted for by an increase in N2O. Maximum rates of nitrite and N2O production by Ms. trichosporium were 6.9 ×5 1016 and 2.2 × 10−17 mol∙cell−1∙day−1, respectively. These values are about 0.2 and 1.6% of the values for Nitrosomonas europaea. Therefore, production of nitrite and N2O by methanotrophs in aquatic environments may not be as significant as that of Nitrosomonas.

Dissimilatory nitrate reduction to nitrate, nitrous oxide, and ammonium by Pseudomonas putrefaciens.

Abstract: The influence of redox potential on dissimilatory nitrate reduction to ammonium was investigated on a marine bacterium, Pseudomonas putrefaciens. Nitrate was consumed (3.1 mmol liter-1), and ammonium was produced in cultures with glucose and without sodium thioglycolate. When sodium thioglycolate was added, nitrate was consumed at a lower rate (1.1 mmol liter-1), and no significant amounts of nitrite or ammonium were produced. No growth was detected in glucose media either with or without sodium thioglycolate. When grown on tryptic soy broth, the production of nitrous oxide paralleled growth. In the same medium, but with sodium thioglycolate, nitrous oxide was first produced during growth and then consumed. Acetylene caused the nitrous oxide to accumulate. These results and the mass balance calculations for different nitrogen components indicate that P. putrefaciens has the capacity to dissimilate nitrate to ammonium as well as to dinitrogen gas and nitrous oxide (denitrification). The dissimilatory pathway to ammonium dominates except when sodium thioglycolate is added to the medium.

A review of nitrite and chloride chemistry: Interactions and implications for cured meats

Abstract: Concerns for the health-related implications of sodium nitrite and sodium chloride in cured meats have lead to reductions in use of both ingredients and there is evidence of chemical interaction between nitrite and chloride in food systems which have implications for cured meats. This review considers the role of chloride in nitrite chemistry and extends this consideration to evaluation of potential changes in cured meat products. Microbiological control depends on nitrite reactivity and a chloride effect has been demonstrated in Clostridium botulinum spore outgrowth and toxin formation. Changes in flavour of cured meats or in development of cured colour are of lesser concern but may take place. More information on specific inhibitory mechanisms by nitrite is needed.

Nitrite-Induced Predisposition of Channel Catfish to Bacterial Diseases

Abstract: Channel catfish, Ictalurus punctatus, continuously exposed to 6 mg/L (ppm) nitrite and intraperitoneally injected with Aeromonas hydrophila had lower bacterial median lethal doses (LD50) than control fish. The clearance rate of injected A. hydrophila was reduced in fish chronically exposed to 5 mg/L (ppm) nitrite. Flexibacter columnaris infections occurred spontaneously in channel catfish exposed to 5 mg/L (ppm) nitrite for 7 days. None of the control fish became infected with F. columnaris.

Amperometric determination of nitrite by oxidation at a glassy carbon electrode

Abstract: Nitrite ion has been determined amperometrically by oxidation at a glassy carbon electrode. A flow injection analysis procedure using this detector has been constructed and some interferences assessed. One of the interfering species was found to be ascorbic acid, and the analysis of an extract of a cooked meat was found to give satisfactory results when ion-interaction chromatography, with amperometric detection, was used.

Nitrite reduction in barley-root plastids: Dependence on NADPH coupled with glucose-6-phosphate and 6-phosphogluconate dehydrogenases, and possible involvement of an electron carrier and a diaphorase

Abstract: Plastids from roots of barley (Hordeum vulgare L.) seedlings were isolated by discontinuous Percoll-gradient centrifugation. Coinciding with the peak of nitrite reductase (NiR; EC 1.7.7.1, a marker enzyme for plastids) in the gradients was a peak of a glucose-6-phosphate (Glc6P) and NADP+-linked nitrite-reductase system. High activities of phosphohexose isomerase (EC 5.3.1.9) and phosphoglucomutase (EC 2.7.5.1) as well as glucose-6-phosphate dehydrogenase (Glc6PDH; EC 1.1.1.49) and 6-phosphogluconate dehydrogenase (6PGDH; EC 1.1.1.44) were also present in the isolated plastids. Thus, the plastids contained an overall electron-transport system from NADPH coupled with Glc6PDH and 6PGDH to nitrite, from which ammonium is formed stoichiometrically. However, NADPH alone did not serve as an electron donor for nitrite reduction, although NADPH with Glc6P added was effective. Benzyl and methyl viologens were enzymatically reduced by plastid extract in the presence of Glc6P+ NADP+. When the plastids were incubated with dithionite, nitrite reduction took place, and ammonium was formed stoichiometrically. The results indicate that both an electron carrier and a diaphorase having ferredoxin-NADP+ reductase activity are involved in the electron-transport system of root plastids from NADPH, coupled with Glc6PDH and 6PGDH, to nitrite.

Nitrate respiration by protozoa (Loxodes spp.) in the hypolimnetic nitrite maximum of a productive freshwater pond

Abstract: SUMMARY. 1 The ciliated protozoon Loxodes dominated the microfaunal community living in the anoxic hypolimnion of Priest Pot, a small productive pond. Its peak abundance close to the oxic-anoxic boundary was always associated with a peak in nitrite (NO2) concentration. Both peaks were usually found in water containing μ1 μmol O2 1-1. 2 The microfauna were concentrated on a 30 μim sieve. The number of Loxodes in the sieve retentate correlated well with the activity of nitrate reductase in the same material, implying that the enzyme was located in Loxodes. It is unlikely that residual bacterial contamination could have accounted for the activity. 3 A doubling of specific electron transport system activity was associated with the transition across the oxic–anoxic boundary. This is consistent with the switch to nitrate respiration and the lower energy yield it provides. 4 Dissimilatory nitrate reduction was deduced to be the source of the nitrite peak. Nitrate was supplied by both run-off and nitrification. 5 It is suggested that Loxodes participates in the dissimilatory sequence of a condensed nitrogen cycle functioning across the oxic—anoxic boundary.

Use of nitrite and hypochlorite treatments in determination of the contributions of IQ-type and non-IQ-type heterocyclic amines to the mutagenicities in crude pyrolyzed materials.

Abstract: The mutagenic heterocyclic amines Glu-P-2, MeA alpha C and Phe-P-1, which possess a 2-aminopyridine structure in their molecule (non-IQ-type mutagens), were found to be inactivated by nitrite treatment under acidic conditions, as observed previously with Trp-P-1, Trp-P-2, Glu-P-1 and A alpha C. In contrast, MeIQx, 4,8- and 7,8-DiMeIQx, which were originally isolated from fried beef or heated model mixtures of creatinine, amino acids and glucose, and which have a 2-aminoimidazole moiety in their molecules (IQ-type mutagens), were very resistant to nitrite treatment like IQ and MeIQ. Both types of mutagenic heterocyclic amines were completely inactivated by treatment with hypochlorite. This differential inactivation of mutagenic heterocyclic amines by nitrite and hypochlorite was used in determination of the contributions of IQ-type and non-IQ-type mutagens to the total mutagenicities of various pyrolyzed materials. The percentage contributions of IQ-type mutagens to the mutagenicities of broiled sardine, fried beef, broiled horse mackerel, cigarette smoke condensate and albumin tar were 88, 75, 48, 6 and 4, respectively.