Showing papers on "Nitrite published in 1970"
TL;DR: In this article, the AutoAnalyzer is used for determining nitrate and nitrite in fresh and sea water and in soil extracts with the help of a modified manual procedure by Wood, Armstrong and Richards, which consists in reduction of nitrate with copperised cadmium and, with the nitrite thus produced, diazotisation of sulphanilamide, the product being coupled with N-1-naphthylethylenediamine to form a highly coloured azo dye, which is measured at 520 nm.
Abstract: Automatic methods for determining nitrate and nitrite in fresh and sea water and in soil extracts with the AutoAnalyzer are described, together with details of the analytical systems. The methods are based on a modification of the manual procedure by Wood, Armstrong and Richards, which consists in reduction of nitrate with copperised cadmium and, with the nitrite thus produced, diazotisation of sulphanilamide, the product being coupled with N-1-naphthylethylenediamine to form a highly coloured azo dye, which is measured at 520 nm. The methods are capable of analysing twenty samples per hour.
551 citations
TL;DR: It is suggested that the production of nitrous oxide by the autotrophic nitrifier, Nitrosomonas, and by such heterotrophic organisms may be of biogeochemical importance.
Abstract: Nitrosomonas europaea oxidizes ammonium to nitrous oxide, a reaction that is enhanced by storing the bacteria at low temperature and by phosphate and high pH. Nitrous oxide is also formed from hydroxylamine by the autotroph. Nitrous oxide is apparently generated from an intermediate in nitrification, and the data suggest that the conversion of this intermediate to nitrite is inhibited by ammonium, hydrazine, or high temperature. Nitrous oxide is also formed during nitrate reduction by Bacillus subtilis, Escherichia coli, and Aerobacter aerogenes and during nitrite reduction by Aspergillus flavus and Penicillium atrocenetum. It is suggested that the production of nitrous oxide by the autotrophic nitrifier, Nitrosomonas, and by such heterotrophic organisms may be of biogeochemical importance.
171 citations
TL;DR: The in vivo and in vitro reactivation of nitrate reductase and the derepression of all the enzymes of the nitrate reducing system are also described.
146 citations
TL;DR: In this paper, it was shown that organic soil constituents are responsible for the reduction of nitrite to N 2 and N 2 O and for the fixation of Nitrite N observed on treatment of soils with nitrite and that inorganic soil constituents were not involved in these reactions.
Abstract: Studies of the gaseous products formed by chemical decomposition of nitrite in soils showed that substantial amounts of N 2 and NO 2 and small amounts of N 2 O were evolved on treatment of neutral and acidic soils with nitrite, the largest amount of N 2 being formed in an acidic soil having a high organic matter content. The amount of NO 2 produced was inversely related to soil pH, but significant amounts of NO 2 were evolved from soils having pH values above 7. The failure of some investigators to detect NO 2 as a product of nitrite decomposition in acidic soils can be attributed to use of closed experimental systems that promoted sorption of this gas by moist soil and conversion of NO 2 to nitrate. A study of the selfdecomposition reaction of nitrous acid showed that this reaction does not proceed according to the classical equation 3HNO 2 = HNO 3 + 2NO + H 2 O and is better represented by the equation 2HNO 2 = NO + NO 2 + H 2 O. Evidence was obtained that organic soil constituents are responsible for the reduction of nitrite to N 2 and N 2 O and for the fixation of nitrite N observed on treatment of soils with nitrite and that inorganic soil constituents are not involved in these reactions. Several experiments indicated that most of the NO 2 evolved on treatment of soils with nitrite is formed by self-decomposition of nitrous acid and by atmospheric oxidation of NO produced by this reaction.
133 citations
TL;DR: In nature, the nitrogen atom exists in the following oxidation states: N205 or HNOa (+5), N02 (+4), N20a or HN02 (+3), NO or H2N20a (+2), NOzNH2; Nz(O)NHzOH (-1), NHzNH2 ( 2), and finally the most reduced state of nitrogen, NHa (-3) as discussed by the authors.
Abstract: Nitrogen plays an integral part in life processes of a biological cell since the synthesis of cellular proteins, amino acids, purines, pyrimidines, nucleic acids, and enzymes is dependent on this essential element. The biological conversion of the oxidized inorganic nitrogen compounds to the ammonia or amino level appears to be an essential metabolic aspect of almost all plants and many microogranisms. They play a vital role in providing nitrogen to many forms of life, including some particular microorganisms and virtually all animals as well as man ; the latter systems lack the ability to reduce more oxidized states of nitrogen and, therefore, they fulfill their obligate nitrogen requirements from the exogenous supply of organic nitrogen and ammonia. It is obvious , therefore, that the inorganic nitrogen is the ultimate nitrogen source for all forms of life on this earth. In nature the nitrogen atom exists in the following oxidation states: N205 or HNOa (+5), N02 (+4), N20a or HN02 (+3), NO or H2N20a (+2), the (+1) oxidation states as represented by N20, HNO, H2N202 and NOzNH2; Nz(O)NHzOH (-1), NHzNH2 ( 2), and finally the most reduced state of nitrogen, NHa (-3). Each of these compounds has been implicated in the inorganic nitrogen metabolism of either intact organisms or their cell-free preparation (51). Although the (+6) oxidation state as represented by NOa, a short-lived compound, has been reported (74), its metabolic role if any is unknown at present. The biological oxidation of reduced inorganic nitrogen compounds is catalyzed predominantly by the bacterial genera Nitrosomonas and Nitro bacter, which oxidize ammonia to nitrite and nitrite to nitrate respectively, a process commonly known as nitrification. These bacteria are obligate chemoautotrophs which derive their energy from the respective primary inorganic oxidations that are coupled to the cellular biosynthetic reactions involving the reduction of carbon dioxide by mechanisms very similar to those of the carbon reduction cycle in photosynthetic organisms. The basic mechanisms of the respiratory and intermediary metabolism of the nitrifying bacteria have been reviewed previously by Lees (44, 45) and by Aleem & Nason (13), and very recently in excellent review articles by Peck (55) and by Wallace & Nicholas (73).
116 citations
TL;DR: Ammonium and nitrate are accumulated in the vacuolated cells of the diatom and these intracellular pools serve as substrate for the assimilatory enzymes, while nitrite is either not accumulated or is concentrated, in a very small cellular compartment.
Abstract: SUMMARY
Apparent Km values for nitrite reductase, glutamic dehydrogenase, and nitrate reductase are of the order 10−4 molar for nitrite, ammonia, and nitrate, respectively while half-saturation constants for the corresponding uptake mechanisms approximate 10−6 molar. Ammonium and nitrate are accumulated in the vacuolated cells of the diatom (about 10 and 40 mmoles/liter cell volume, respectively) and these intracellular pools serve as substrate for the assimilatory enzymes. Nitrite is either not accumulated or is concentrated, in a very small cellular compartment.
Ammonium and nitrate in the external medium exert modifying effects on uptake and assimilatory mechanisms which can be distinguished from effects of the ions accumulated within the cells. Several of these effects are described and fitted into a general scheme of nitrogen assimilation by D. brightwellii.
107 citations
TL;DR: Oxygen inhibited nitrite release in the anaerobic intact-tissue assay, but under aerobic conditions and in the presence of 2-heptyl-4-hydroxyquinoline-N-oxide or antimycin A, nitrate reduction increased to rates comparable to those observed under anaerobiosis.
Abstract: Nitrate reductase activity in barley (Hordeum vulgare L cv Himalaya) aleurone layers has been determined in the intact tissue, using two different methods The first method measures the rate of appearance of H(2) (18)O produced during the reduction of KN(18)O(3) The second assay measures excreted nitrite resulting from nitrate reduction under anaerobic conditions Nitrite production in this anaerobic, intact-tissue assay was dependent upon the presence of phosphate (pH 75) and was increased by ethanol and bisulfiteAfter ten hours of nitrate induction, nitrate reductase activities measured by the KN(18)O(3) assay are one-sixth, and those measured by the anaerobic intact-tissue assay are one-third, of those observed in cell-free extracts of aleurone layers Addition of ethanol to the anaerobic intact-tissue medium increased the rate of nitrate reduction to a level greater than that found in the cell-free assayOxygen inhibited nitrite release in the anaerobic intact-tissue assay However, under aerobic conditions and in the presence of 2-heptyl-4-hydroxyquinoline-N-oxide or antimycin A, nitrate reduction increased to rates comparable to those observed under anaerobiosis Neither of these electron transport inhibitors affected anaerobic nitrate reduction, though they were effective in inhibiting oxygen uptake in separate experiments
86 citations
TL;DR: Resting cells of Corynebacterium nephridii reduce nitrate, nitrite, and nitric oxide to nitrous oxide under anaerobic conditions and hydroxylamine increases gas evolution from nitrite but inhibits the reduction of nitricoxide toNitrous oxide.
Abstract: Resting cells of Corynebacterium nephridii reduce nitrate, nitrite, and nitric oxide to nitrous oxide under anaerobic conditions. Nitrous oxide production from nitrite was optimal from pH 7.0 to 7.4. The stoichiometry of nitrous oxide production from nitrite was 99% of the theoretical-two moles of nitrite was used for each mole of nitrous oxide detected. Hydroxylamine increases gas evolution from nitrite but inhibits the reduction of nitric oxide to nitrous oxide. Hydroxylamine is converted to nitrogenous gas(es) by resting cells only in the presence of nitrite. Under certain conditions nitric oxide, as well as nitrous oxide, was detected.
75 citations
TL;DR: The separation of an autoxidizable brown pigment, P582, from Desulfotomaculum nigrificans is described, which was characterized by absorption maxima in the oxidized state at 392, 582, and 700 nm and was unaffected by chelating agents.
Abstract: The separation of an autoxidizable brown pigment, P582, from Desulfotomaculum nigrificans is described. It reacted with Na2S2O4 and was characterized by absorption maxima in the oxidized state at 392, 582, and 700 nm. In the presence of Na2S2O4, P582 formed complexes with CO and, under alkaline conditions, pyridine. There was no reaction with cyanide. The molecular weight of P582 was approximately 145,000, and the purest preparations contained Fe, Zn, and acid-labile sulfide but not Cu, Mo, or Mn. Preparations of P582 catalyzed the reduced methyl viologen (MVH)-linked reduction of sulfite, hydroxylamine, and nitrite but not of sulfate, thiosulfate, or nitrate. Reduced pyridine nucleotides did not substitute for MVH. A major product of the MVH-sulfite reaction was sulfide. CO partially inhibited the enzymatic activities. Sulfite, hydroxylamine, and nitrite and CO caused changes in the spectrum of Na2S2O4-reduced P582. Fe2+-chelating reagents reacted with part of the Fe of P582 and caused partial losses of labile sulfide and enzymatic activity. The spectral and CO-reacting properties of P582 were, however, unaffected by chelating agents. The reaction between P582 and chelating agents was stimulated by reducing agents.
73 citations
71 citations
TL;DR: In this paper, it was shown that soil minerals and metallic cations do not promote chemical decomposition of nitrite in soils and do not play a significant role in the processes leading to gaseous loss of nitrogen from soils through chemodenitrification.
Abstract: Work reported indicates that soil minerals and metallic cations do not promote chemical decomposition of nitrite in soils and do not play a significant role in the processes leading to gaseous loss of nitrogen from soils through chemodenitrification. No reactions promoting nitrite decomposition were observed in studies of the effects of soil minerals on the decomposition of nitrite in pH 5 buffer solution, and investigations of the reactions of nitrite with metallic cations provided no indications that chemodenitrification in soils is promoted by metallic cations. Of various metallic cations tested, only ferrous, cuprous and stannous ions promoted nitrite decomposition, and soils normally do not contain sufficient amounts of these cations to promote nitrite decomposition under the conditions known to be suitable for chemodenitrification.
TL;DR: Spectrophotometric and fluorometric procedures have been developed for the analysis of nitrite ion based upon 2,3-naphthotriazole formation with the reagent 2, 3-diaminonaphthalene.
Abstract: Spectrophotometric and fluorometric procedures have been developed for the analysis of nitrite ion based upon 2,3-naphthotriazole formation with the reagent 2,3-diaminonaphthalene. Reaction conditions, interferences, solvent extraction, and sensitivity of the procedures are discussed.
TL;DR: In the sea, it appears that, in certain micro-environments, decomposition of particulate matter releases ammonia with its subsequent oxidation to nitrite, which is a major source of nitrite in certain areas of the sea.
Abstract: The relative importance of 3 different sources for biological production of nitrite in seawater was studied. Decomposition of fecal pellets of the copepod Calanus helgolandicus (at a concentration of approximately 12 μg-at N/l), in seawater medium, released small amounts of ammonia over a 6 week period. It nitrifying bacteria were added to the fecal pellets nitrite was barely detectable over the same period. Decomposition of phytoplankton (present at a concentration of about 8 μg-at particulate plant N/l) with added heterotrophic bacteria, released moderate amounts of ammonia over a 12 week period. If the ammonia-oxidizing bacterium Nitrosocystis oceanus was added to the decomposing algae, nitrite was produced at a rate of 0.2 μg-at N/l/week. Heterotrophic nitrification was not observed when 7 open-ocean bacteria were tested for their ability to oxidize ammonia. The diatom Skeletonema costatum, either non-starved or starved of nitrogen, produced nitrite when growing with 150 or 50 μg-at NO2--N/l at a light intensity of about 0.01 ly/min. When nitrate in the medium was exhausted, S. costatum assimilated nitrite. If starved of vitamin B12, both non-N-starved and N-starved cells of S. costatum produced nitrite in the medium with 150 μg-at NO3--N/l. Nitrate was not exhausted and cell densities reached 2x105/ml due to vitamin B12 deficiency. If light intensity was reduced to 0.003 ly/min under otherwise similar conditions, cells did not grow due to insufficient light, and nitrite was not produced. In the sea, it appears that, in certain micro-environments, decomposition of particulate matter releases ammonia with its subsequent oxidation to nitrite. The amounts of these nutrients and the rate at which they are produced are dependent upon the nature of the materials undergoing decomposition and the associated bacteria. In certain other areas of the sea, where phytoplankton standing stock is high and nitrate is non-limiting, excretion by these organisms is a major source of nitrite.
TL;DR: Calculations on the distribution of these enzymes, when compared with the Distribution of pyruvate kinase and cytochrome c oxidase activity, demonstrate that the larger part of both nitrate and nitrite reductase is located outside of the chloroplast.
Abstract: Chloroplasts have been isolated from spinach and from sunflower which retain their outer membrane and their stroma protein as determined both by ability to fix CO2 and evolve O2 at high rates, and by appearance under the phase contrast microscope. Such chloroplasts contain both nitrate and nitrite reductase activity. However, calculations on the distribution of these enzymes, when compared with the distribution of pyruvate kinase and cytochrome c oxidase activity, demonstrate that the larger part of both nitrate and nitrite reductase is located outside of the chloroplast.
Journal Article•
TL;DR: The intensity of the abnormal electron spin resonance signal previously observed in the livers of rats which were fed various chemical carcinogens is found to depend on the intake of the carcinogen, protein, and nitrate or nitrite.
Abstract: The intensity of the abnormal electron spin resonance signal previously observed in the livers of rats which were fed various chemical carcinogens is found to depend on the intake of the carcinogen, protein, and nitrate or nitrite. Nitrite enhances the intensity of the abnormal electron spin resonance signal and inhibits the carcinogenicity of 2-acetyl-aminofluorene. The appearance of the signal-bearing complex and the possible mechanism of its anticarcinogenic activity are discussed.
TL;DR: Isolates of heterotrophic organisms from a Teak soil were tested for their ability to produce nitrite and/or nitrate in a glucose-peptone medium, soil organic matter extract, and in sterilized soils as mentioned in this paper.
Abstract: Isolates of heterotrophic organisms from a Teak soil were tested for their ability to produce nitrite and/or nitrate in a glucose-peptone medium, soil organic matter extract, and in sterilized soils. The amounts of nitrite and nitrate formed varied with the medium used. The ability to produce nitrite and/or nitrate was more common and more efficient among the fungi where up to 4.76 ppm nitrite-nitrogen and 12.88 ppm nitrate-nitrogen were obtained after 14 days incubation.
TL;DR: Different spectra, at room and liquid N2 temperatures, of S2O42−-, and NO2−-reduced intact cells and cell-free preparations of Nitrobacter agilis demonstrated the presence of cytochromes of the c- and a-types, suggesting a metal component in the electron transport chain at the site prior to cytochrome c.
TL;DR: In this article, it is suggested that the nitrous oxide is formed by the decomposition of cis-hyponitrite, which, in turn, is produced by the dimerisation of nitroxyl, NO−, one of the initial products of the reaction.
Abstract: Hydroxylamine and peroxonitrite react in alkaline solution in the absence of oxygen, in a metal-ion catalysed reaction, giving nitrite and nitrous oxide. It is suggested that the nitrous oxide is formed by the decomposition of cis-hyponitrite, which, in turn, is produced by the dimerisation of nitroxyl, NO–, one of the initial products of the reaction. Evidence is presented to show the presence of NO– as an intermediate and the instability of cis-hyponitrite under the conditions of the reaction. A little trans-hyponitrite is probably formed in this reaction, presumably also by NO– dimerisation. In the presence of oxygen, the stoicheiometry is changed, hydroxylamine being oxidised to nitrite with apparently no loss of peroxonitrite. It is suggested that this is due to the reformation of peroxonitrite by the addition of oxygen to NO–. The stability of Angeli's salt has been re-investigated while we have been unable to prepare sodium β-oxohyponitrite by the N2O4 oxidation of hyponitrite. Both these were considered as intermediates.
TL;DR: In this paper, an investigation of the formation of nitrosamines from the naturally occurring amines in fish and added nitrite (sometimes used as a preservative) was carried out, and the results indicate that certain kinds of fish, especially those rich in amines, can form dimethylnitrosamine (DMN) during cooking with nitrite.
TL;DR: Cell-free extracts of Nitrosomonas europaea prepared by a French Pressure Cell actively oxidized ammonia to nitrite only when protected or activated by bovine serum albumin, Mg2+ or polyamines such as spermine.
TL;DR: No activity with hyponitrite or sulphite was observed with reduced benzyl viologen as electron donor in either the nitrite reduct enzyme or the hydroxylamine reductase systems, but pyruvic oxime produced about 4% of the activity of hydroxyamine.
Abstract: Nitrite reductase was purified between 760- and 1300-fold from vegetable marrow (Cucurbita pepo L.) and residual hydroxylamine reductase activity was low or negligible by comparison. With ferredoxin as electron donor, nitrite loss and ammonia formation at pH7.5 were stoicheiometrically equivalent. Crude nitrite reductase preparations showed negligible activity with NADPH as electron donor maintained in the reduced state by glucose 6-phosphate, whereas by comparison, activity was high when either ferredoxin or benzyl viologen were also present and reduced by the NADPH–glucose 6-phosphate system, whereas FMNH2 produced variable and relatively low activity under the same conditions. At pH values below 7, non-enzymic reactions occurred between reduced benzyl viologen and nitrite, and intermediate reduction products were inferred to be produced instead of ammonia. Activity with ferredoxin (0.1mm), reduced by chloroplast grana in the light, was 25 times that produced with ferredoxin (40μm) reduced with NADPH and glucose 6-phosphate. For an approximate molecular weight 61000–63000 derived by chromatography on Sephadex G-100 and G-200, and a specific activity of 46μmol of nitrite reduced/min per mg of protein with light and chloroplast grana, a minimum turnover number of 3×103mol of nitrite reduced/min per mol of enzyme was found. Two hydroxylamine reductases were separated on Sephadex gels. One (HR1) was initially associated with nitrite reductase during gel filtration but disappeared during later fractionation. This HR1 fraction showed nearly comparable activity with reduced benzyl viologen, ferredoxin or FMNH2. The other (HR2), of molecular weight approx. 35000, reacted with reduced benzyl viologen but showed negligible activity with ferredoxin or NADPH. Activity with FMNH2 was associated with an irregular trailing boundary during gel filtration, with much diminished activity in the HR2 region. Activity with NADPH was about 30% of that with FMNH2, reduced benzyl viologen or ferredoxin and was considered to reside in fraction HR1. Hydroxylamine yielded ammonia under all assay conditions. No activity with hyponitrite or sulphite was observed with reduced benzyl viologen as electron donor in either the nitrite reductase or the hydroxylamine reductase systems, but pyruvic oxime produced about 4% of the activity of hydroxylamine.
TL;DR: In this paper, the mechanism of denitrification was studied in raw seawater collected from the oxygen minimum layer of the northeast tropical Pacific Ocean and two separate and not simultaneous stages were evident.
Abstract: The mechanism of denitrification was studied in raw seawater collected from the oxygen minimum layer of the northeast tropical Pacific Ocean. Two separate and not simultaneous stages in the denitrification process were evident. During the first stage, nitrate was reduced to nitrite. Thereafter, an additional reaction occurred in which nitrite was further reduced. The rates of reduction appear to be independent of nitrate concentration. Ammonia and nitrous oxide were not significant products of nitrate reduction.
TL;DR: The nitrite yields from alpha irradiation were appreciably lower than the yields from gamma and beta irradiations at lower acid concentrations but continually increased with increasing acid concentration, while similarity of the Gamma and beta yields substantiated this unusual trend.
Abstract: The radiolysis of nitric acid solutions was investigated using gamma, beta and alpha radiation. Solutions were gamma-irradiated under various conditions and analyzed for all stable products. Solutions that were alpha- or beta-irradiated were analyzed for nitrite ion only.
Nitrite ion, the major radiolysis product, was determined as a function of nitric acid concentration. A nitrite scavenger, p-nitroaniline, was added to prevent the nitrite ion from reacting prior to analysis. The nitrite yields from alpha irradiation were appreciably lower than the yields from gamma and beta irradiations at lower acid concentrations but continually increased with increasing acid concentration. The nitrite yields from gamma or beta irradiation increased with increasing acid concentration up to about 1 M but then decreased. Similarity of the gamma and beta yields substantiated this unusual trend. Previous investigations of neutral nitrate solutions have always shown an increase in yields at the higher nitrate concentrations. A mechanism, based on L.E.T. effects on three radiolytic reactions, has been postulated to explain the differences in yields between alpha and gamma (or beta) irradiation.
TL;DR: The second-phase changes can be accounted for by the energy-dependent accumulation in an osmotically active form of K(+) and other metabolites by cells depleted of intracellular solutes.
Abstract: The addition of nitrate to cultures of Spirillum itersonii incubated under low aeration produced a diauxic growth pattern in which the second exponential phase was preceded by the appearance of nitrite in the medium. The organism also grew anaerobically in the presence of nitrate. Nitrate reductase activity could be demonstrated in cell-free extracts by use of reduced methyl viologen as the electron donor. The enzyme was located in the supernatant fraction after centrifugation of extracts for 2 hr at 40,000 × g, and it sedimented as a single peak when centrifuged in a sucrose gradient. Nitrate reductase activity was found in cells grown with low aeration without nitrate, but was increased about twofold by addition of nitrate. Enzyme activity was negligible in cells grown with high aeration. The proportion of soluble cytochrome c was increased two- to threefold in cells grown with nitrate. The specific activities of nitrate reductase and soluble cytochrome c rose when nitrate or nitrite was added to cell suspensions incubated with low aeration; nitrite was more effective than nitrate during the early stages of incubation. A nitrate reductase-negative mutant synthesized increased amounts of soluble cytochrome c in response to nitrate or to nitrite in the cell suspension system. It is concluded that enhanced synthesis of soluble cytochrome c does not require the presence of a functional nitrate reductase.
TL;DR: The rapid hydrolysis of polyphosphate after the transfer of stationary-phase cells into new growth solution was found to be triggered primarily by the higher pH of the fresh growth solution, and the efflux of orthophosphate during culture growth was not associated with a decrease in the pH ofthe growth solution.
Abstract: After inoculation of a stationary-phase culture of Nitrosomonas europaea into fresh growth solution, the cell-associated orthophosphate increased rapidly to 800 mumoles/g (wet weight), whereas the acid-insoluble long-chain polyphosphate content decreased rapidly to 22 mumoles/g. As growth proceeded, the orthophosphate content decreased rapidly to a level of 15 mumoles/g and the long-chain polyphosphate content gradually increased to 60 to 90 mumoles/g. When the pH of a culture of Nitrosomonas decreased during growth below approximately 7.4, the rate of nitrite and polyphosphate synthesis increased and the ratio of change in protein to change in nitrite decreased. When the pH of the culture was maintained above 7.6 throughout growth, polyphosphate accumulation, an increased rate of nitrite and polyphosphate synthesis, and a decreased ratio of change in protein to change in nitrite were not observed. Cells of Nitrosomonas apparently accumulated polyphosphate when adenosine triphosphate generated during the oxidation of ammonia to nitrite was not efficiently used to promote an increase in cell mass. The rapid hydrolysis of polyphosphate after the transfer of stationary-phase cells into fresh growth solution was found to be triggered primarily by the higher pH of the fresh growth solution. The efflux of orthophosphate during culture growth was not associated with a decrease in the pH of the growth solution. Data on the chemical composition of Nitrosomonas are presented.
TL;DR: In this paper, the Ap horizons of three Chernozemic Black soils of acid, neutral and alkaline pH were incubated with the addition of ammonium sulfate and urea in order to trace the formation and/or disappearance of ammonIUM, nitrite and nitrate.
Abstract: Samples of the Ap horizons of three Chernozemic Black soils of acid, neutral and alkaline pH were incubated with the addition of ammonium sulfate and urea in order to trace the formation and/or disappearance of ammonium, nitrite and nitrate. A nitrogen concentration of 50 ppm N (air-dry basis) resulted in little difference of nitrification rate in 12 days between ammonium sulfate and urea, although considerable differences existed between soils. At high nitrogen concentrations (200, 400, and 800 ppm N), urea led to high nitrite concentrations in the neutral Wellwood soil, as well as showing a higher rate of ammonium oxidation in all soils, particularly the acid Holland soil. Expressed as the difference between initial total mineral N and total mineral N after incubation, nitrogen showed a loss at the higher fertilizer rates with the Wellwood and Holland soils. This was greatest in the ammonium sulfate treatment with the initially most acid soil.
TL;DR: It is concluded that while intact chloroplasts do have the ability to reduce both NO3- and NO2- at low rates, they do not synthesize appreciable amounts of amino acid directly, and this fact must be considered when formulating any pathways for nitrogen metabolism during photosynthesis.
Abstract: Intact chloroplasts isolated from spinach reduced NO3- and NO2- in the light without the addition of either co-factors or added enzymes The maximum rate observed, however, for the reduction of NO3- was approximately 3μMoles hr-1 mg-1 (chlorophyll) and for NO2- 6 μMoles hr-1 mg-1 (chlorophyll) These rates were consistent with the enzyme content of whole chloroplasts, but much lower than those found in whole leaf extracts
TL;DR: A cell free, particulate extract of barley roots has been shown to be capable of producing ammonia from nitrate solely in the presence of compounds known to be in the root, dependent on added ATP and to a lesser extent on electron donors.
TL;DR: The data are interpreted as indicating that the de-esterification of nitroglycerin by serum is enzymatic and involves the reduction of organic nitrate to organic nitrite followed by the hydrolysis of nitrite ester to inorganic nitrite.