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Showing papers on "Nitrite published in 1974"



Journal ArticleDOI
01 Sep 1974-Planta
TL;DR: The assimilation of nitrate, nitrite and ammonia in barley, wheat, corn and bean leaves was studied using 15N-labelled molecules and either leaf chamber experiments with the uptake of the nitrogen species in the transpiration stream, or vacuum-infiltration experiments.
Abstract: The assimilation of nitrate, nitrite and ammonia in barley, wheat, corn and bean leaves was studied using 15N-labelled molecules and either leaf chamber experiments with the uptake of the nitrogen species in the transpiration stream, or vacuum-infiltration experiments. The assimilation of 15NO3− into amino nitrogen was strictly dependent on light and ceased abruptly when the light was extinguished. If the leaves were exposed to air, CO2-free air or N2 there was no effect on the rate of NO3− assimilation over 0.5 h. After 1.25 h of CO2-free air, NO3− assimilation into amino acids was sharply reduced. Resupply of air at this time stimulated NO3− assimilation and restored it to the rate observed in leaves exposed to air only. There was no recovery by tissue pretreated for 1.25 h in N2 and subsequently resupplied with air. Incorporation of 15NO2− was also markedly dependent on light with little reduction occurring in the dark. Incorporation of 15NH4+ into amino acids was stimulated 5 fold by light but considerable incorporation occurred in the dark. The presence of 100 mM NO3− had no effect on the rate of incorporation of 15NO2− or 15NH4+. Nitrite at 1 mM had no effect on 15NO3− incorporation but at 10 mM inhibited it completely after 0.5 h. Ammonia at 1 mM had no effect on 15NO3− or 15NO2− incorporation and while 10 mM inhibited incorporation for 0.5 h this inhibition did not persist.

152 citations


01 Jan 1974
TL;DR: In this article, two postassay treatments were found that markedly enhanced the extent of nitrite color formation and apparent nitrate reductase activity and showed that the zinc acetate removes extract factor(s) that interfere with color development, because it does not remove the NADH.
Abstract: Nitrate reductase activity is most commonly assayed by measurement of product formation. Excess NADH and factor(s) present in the enzyme extract that interfere with the diazotization and azo color complex of nitrite cause a depression of apparent nitrate reductase activity. Two postassay treatments were found that markedly enhanced the extent of nitrite color formation and apparent nitrate reductase activity. The procedure involves stopping the reaction with zinc acetate (50 ,umoles per ml of reaction mix), followed by removal of the precipitate by centrifugation. Presumably the zinc acetate removes extract factor(s) that interfere with color development, because it does not remove the NADH. Phenazine methosulfate (15 nmoles per ml of reaction mix) is added to aliquots of the supernatant and allowed to stand for 20 min at 30 C to oxidize the residual NADH before color development.

127 citations


Journal ArticleDOI
TL;DR: Two postassay treatments were found that markedly enhanced the extent of nitrite color formation and apparent nitrate reductase activity.
Abstract: Nitrate reductase activity is most commonly assayed by measurement of product formation. Excess NADH and factor(s) present in the enzyme extract that interfere with the diazotization and azo color complex of nitrite cause a depression of apparent nitrate reductase activity. Two postassay treatments were found that markedly enhanced the extent of nitrite color formation and apparent nitrate reductase activity. The procedure involves stopping the reaction with zinc acetate (50 μmoles per ml of reaction mix), followed by removal of the precipitate by centrifugation. Presumably the zinc acetate removes extract factor(s) that interfere with color development, because it does not remove the NADH. Phenazine methosulfate (15 nmoles per ml of reaction mix) is added to aliquots of the supernatant and allowed to stand for 20 min at 30 C to oxidize the residual NADH before color development.

121 citations


Journal Article
TL;DR: Twelve common drugs that are tertiary amines react with nitrite in aqueous solution at ph 3 to 4 to form dialkylnitrosamines that are known carcinogens.
Abstract: Summary Twelve common drugs that are tertiary amines react with nitrite in aqueous solution at ph 3 to 4 to form dialkylnitrosamines that are known carcinogens. Aminopyrine gave dimethylnitrosamine in 30% yield or higher at all concentrations down to 50 ppm (with 25 ppm nitrite); the other product of this reaction was the nitrite salt of 4-hydroxyantipyrine. The other drugs, when present at 0.01 m with 0.04 m nitrite, formed nitrosamines in yields ranging from 0.03% from dextropoxyphene to 2.4% from lucanthone in 4 hr at 37°.

116 citations


Journal ArticleDOI
TL;DR: In this paper, the free radicals NO, NO2, and O− are destroyed by solar photolysis, and the nitrite reactions sum to a photocatalyzed conversion of dissolved oxygen and water to OH radicals.
Abstract: Nitrate and nitrite ions are destroyed by solar photolysis. Rate estimates for these processes in tropical surface waters imply relatively rapid reaction of both ions and yield minimum production rates for the reactive products. Products include the free radicals NO, NO2, and O−; at pH 8, O− yields OH radical. If NO is converted to nitrite by dark reactions, the nitrite reactions sum to a photocatalyzed conversion of dissolved oxygen and water to OH radicals. Kinetic calculations and flash photolysis experiments both indicate that in seawater, OH reacts rapidly and semiquantitatively with bromide to yield dissolved bromine atoms, which complex with halide ions. Subsequent reactions of potential geochemical significance include recombinations, heavy metal redox processes, and selective oxidation of organic matter. These processes may affect marine aerosols as well as surface seawater.

113 citations


Journal ArticleDOI
TL;DR: Photoinactivation of ammonia oxidation in cells of Nitrosomonas was shown to follow first-order kinetics with a rate constant proportional to incident light intensity, and the amount per cell of the following constituents was not measurably altered by photoinactivation.
Abstract: Photoinactivation of ammonia oxidation in cells of Nitrosomonas was shown to follow first-order kinetics with a rate constant proportional to incident light intensity. The action spectrum for photoinactivation consisted of a broad peak in the ultraviolet range, where both hydroxylamine and ammonia oxidation were affected, and a shoulder at approximately 410 nm where only ammonia oxidation was affected. In photoinactivated cells, hydroxylamine but not ammonia was oxidized to nitrite and hydroxylamine but not ammonia caused reduction of cytochromes in vivo. The amount per cell of the following constituents was not measurably altered by photoinactivation: cytochromes b, c, a, and P460; ubiquinone; phospholipid; free amino acids; hydroxylamine-dependent nitrite synthetase; nitrite reductase; p-phenylenediamine oxidase; and cytochrome c oxidase. Malonaldehyde or lipid peroxides were not detected in photoinactivated cells. Photoinactivation was prevented (i) under anaerobic conditions, (ii) in the presence of methanol, allylthiourea, thiosemicarbazide, hydroxylamine, ethylxanthate, or CO at concentrations wich caused 100% inhibition of ammonia oxidation, and (iii) at concentrations of ammonia or hydroxylamine which gave a rapid rate of nitrite production. Recovery of ammonia oxidation activity in 90% inactivated cells took place in 6 h, required an energy and/or nitrogen source, and was inhibited by 400 mug of chloramphenicol per ml.

101 citations


Journal ArticleDOI
TL;DR: The Progressive Fish-Culturist: Vol. 36, No. 2, pp. 86-89 as discussed by the authors, discusses Nitrate and Nitrite Toxicity to Salmonoid Fishes.
Abstract: (1974). Nitrate and Nitrite Toxicity to Salmonoid Fishes. The Progressive Fish-Culturist: Vol. 36, No. 2, pp. 86-89.

98 citations


Journal ArticleDOI
12 Apr 1974-Nature
TL;DR: In the absence of catalyst the nitrosation of N-methylaniline and some other secondary amines is maximal at pH 3, but in the presence of thiocyanate the reaction proceeds much more rapidly in acid conditions, such as in gastric juice, between pH 1 and 2.
Abstract: CARCINOGENIC nitrosamines are formed by chemical reaction between nitrous acid and secondary and some tertiary amines in the stomachs of rodents1–3. Nitrosamines could be formed similarly in the human stomach and so present a carcinogenic hazard to man. The nitrosation reaction is catalysed by some anions4 particularly thiocyanate5,6. Thiocyanate is secreted in saliva which in non-smokers normally contains about 50 mg l−1 (approximately 1 mM) but in smokers contains three to four times this concentration7. In the absence of catalyst the nitrosation of N-methylaniline and some other secondary amines is maximal at pH 3, but in the presence of thiocyanate the reaction proceeds much more rapidly in acid conditions, such as in gastric juice, between pH 1 and 2 (Fig. 1). At pH 1.5, 1.0 mM thiocyanate increases the rate of reaction about 550 times. Under these acid conditions below pH 2 the nitrosation reaction rate is proportional to the concentrations of (1), nitrite; (2), thiocyanate; and (3), amine8. At pH 3.5 and greater thiocyanate has less catalytic action and the predominant reaction is proportional to the square of the nitrite concentration, but is slow.

85 citations


Journal ArticleDOI
TL;DR: The findings suggest that nitrate transport is not dependent upon nitrate reduction and that these two processes are separate events in the assimilation of nitrate.
Abstract: Nitrate uptake in Neurospora crassa has been investigated under various conditions of nitrogen nutrition by measuring the rate of disappearance of nitrate from the medium and by determining mycelial nitrate accumulation. The nitrate transport system is induced by either nitrate or nitrite, but is not present in mycelia grown on ammonia or Casamino Acids. The appearance of nitrate uptake activity is prevented by cycloheximide, puromycin, or 6-methyl purine. The induced nitrate transport system displays a Km for nitrate of 0.25 mM. Nitrate uptake is inhibited by metabolic poisons such as 2,4-dinitrophenol, cyanide, and antimycin A. Furthermore, mycelia can concentrate nitrate 50-fold. Ammonia and nitrite are non-competitive inhibitors with respect to nitrate, with Ki values of 0.13 and 0.17 mM, respectively. Ammonia does not repress the formation of the nitrate transport system. In contrast, the nitrate uptake system is repressed by Casamino Acids. All amino acids individually prevent nitrate accumulation, with the exception of methionine, glutamine, and alanine. The influence of nitrate reduction and the nitrate reductase protein on nitrate transport was investigated in wild-type Neurospora lacking a functional nitrate reductase and in nitrate non-utilizing mutants, nit-1, nit-2, and nit-3. These mycelia contain an inducible nitrate transport system which displays the same characteristics as those found in the wild-type mycelia having the functional nitrate reductase. These findings suggest that nitrate transport is not dependent upon nitrate reduction and that these two processes are separate events in the assimilation of nitrate.

82 citations


Journal ArticleDOI
01 Feb 1974-Nature
TL;DR: The current investigations concern the possibility that interactions of nitrite with certain food components could result in the formation of C-nitroso compounds whose biological behaviour is largely unknown but from the few reports in the literature are much weaker carcinogens than the corresponding N- Nitroso derivatives.
Abstract: THE discovery of volatile N-nitroso compounds1 in certain foodstuffs2 treated with nitrite and/or nitrate has prompted investigation into the conditions likely to give rise to them in food processing and also during digestion. Although other reactions of food components with nitrate and nitrite under physiological conditions are known3, the fate of the total nitrate and nitrite added to foodstuffs as preservatives and that ingested with food has not been established. Our current investigations concern the possibility that interactions of nitrite with certain food components could result in the formation of C-nitroso compounds whose biological behaviour is largely unknown but from the few reports in the literature4–7 are much weaker carcinogens than the corresponding N-nitroso derivatives. The nitrophenols, however, produced by oxidation of the corresponding nitrosophenol, could affect the energy-yielding processes of the cell by uncoupling oxidative phosphorylation6.

Journal ArticleDOI
TL;DR: Chloroplasts are functionally able and contain the enzyme complement necessary to utilize light energy for the reduction of nitrite to amino nitrogen, and should be considered as a major site for in vivo amino-nitrogen synthesis in green plants.
Abstract: The assimilation of nitrite leading to de novo synthesis of amino nitrogen in a chloroplast-enriched fraction isolated from freshly harvested young spinach ( Spinacia oleracea L.) leaves was demonstrated. The preparations showed approximately 55% intact chloroplasts as determined by light scattering properties and fixed CO 2 at rates of approximately 100 μmoles hr −1 mg chlorophyll −1 . The chloroplast-enriched fraction contained the enzymes, nitrite reductase and NADPH-glutamate dehydrogenase, needed for the reduction of nitrite and incorporation of ammonia into glutamate. Kinetic studies showed that the reduction of nitrite by the chloroplast-enriched fraction is light-dependent, and the process proceeds at rates of 6 to 12 μmoles hr −1 mg chlorophyll −1 . The addition of nitrite to the chloroplast preparation caused a 3-fold increase in the production of α-amino nitrogen when compared with the control without nitrite. There was a stoichiometric relation between amino-nitrogen synthesis and nitrite disappearance from the medium. The ratio of amino-nitrogen: NO 2 − ranged from 0.6 to 0.9. The initial rate of amino-nitrogen production was faster when α -ketoglutarate was added to the nitrite reducing chloroplast medium than when it was omitted. However, these high rates were not sustained and the total amino-nitrogen production at the end of a 30-minute period was only slightly higher. These data show that chloroplasts are functionally able and contain the enzyme complement necessary to utilize light energy for the reduction of nitrite to amino nitrogen. Thus, chloroplasts should be considered as a major site for in vivo amino-nitrogen synthesis in green plants.

Journal ArticleDOI
TL;DR: Two groups of 20 yearling rainbow trout were exposed continuously to inflowing water containing 0.15 and 0.55 mg/liter nitrite as nitrite nitrogen (NO2N) for 48 and 24 hr, respectively and developed methemoglobinemia.
Abstract: Two groups of 20 yearling rainbow trout were exposed continuously to inflowing water containing 0.15 and 0.55 mg/liter nitrite as nitrite nitrogen (NO2N), for 48 and 24 hr, respectively. Both groups developed methemoglobinemia but mortality occurred only at the highest concentration (55%). Salmon exposed to 0.50 mg/liter NO2N for 24 hr developed methemoglobinemia and suffered a 40% mortality. Fingerling trout were less sensitive to nitrite than yearlings.


Journal ArticleDOI
TL;DR: In this article, the detection of dimethylnitrosamine was verified by thin-layer and gas chromatography, ultraviolet and infrared spectrometry, and combined gas chromatrophy-mass spectrometer.
Abstract: Added trimethylamine is converted to dimethylamine in samples of raw sewage and lake water, and the secondary amine thus formed or added dimethylamine disappears with time. The rates of formation and disappearance of dimethylamine are governed by the pH and the type and amount of inorganic N present. Ammonium is generated from both of the amines. Dimethylnitrosamine, a potent carcinogen, is formed in small amounts in samples of sewage and lake water receiving dimethylamine and nitrite, the maximum nitrosamine level detected rising with increasing acidity and increasing dimethylamine and nitrite concentrations. Dimethylnitrosamine also appears in sewage and lake water samples receiving trimethylamine. Microorganisms are involved in some stage of the conversion of the tertiary amine to the secondary amine and dimethylnitrosamine in sewage because these products are not found in sterilized sewage. The fungicide thiram (tetramethylthiuram disulfide) is converted to dimethylamine in sterilized sewage at pH 4.0, and small amounts of dimethylnitrosamine are also produced in the presence of nitrite; the yields of both products are far greater in nonsterile, thiram-amended sewage. The identification of dimethylnitrosamine was verified by thin-layer and gas chromatography, ultraviolet and infrared spectrometry, and combined gas chromatrophy-mass spectrometry.

Journal ArticleDOI
TL;DR: In this paper, the reduction of nitrite at platinum electrode in 0.1 M HClO 4 leads to a number of products including 60.7% NH 2 OH, 18.8% N 2 O and 21.6% NH 3.

Journal ArticleDOI
01 Sep 1974-Planta
TL;DR: Chloroplast preparations from spinach leaves containing a high percentage of intact chloroplasts were capable of light dependent nitrite reduction at rates around 9 μmol/mg chlorophyll/h for at least 50 min, inhibited by DCMU but unaffected by uncouplers of photosynthetic phosphorylation.
Abstract: Chloroplast preparations from spinach leaves containing a high percentage of intact chloroplasts were capable of light dependent nitrite reduction at rates around 9 μmol/mg chlorophyll/h for at least 50 min. This reduction was inhibited by DCMU but unaffected by uncouplers of photosynthetic phosphorylation. Nitrite reduction was not accompanied by a stoichiometric evolution of oxygen evolution. The disappearance of nitrite was accompanied by an approximately stoichiometric formation of reduced nitrogen.

Journal ArticleDOI
TL;DR: The effects of three patented nitrification inhibitors on transformations of urea N in soils were studied by determining the effects of these compounds (10 μg/g of soil) on urea hydrolysis, ammonia volatilization, and production of ammonium, nitrite, and nitrate in soils incubated under aerobic conditions (30°C, 60% WHC) after treatment with urea (400 μg of Urea N/g).
Abstract: The effects of three patented nitrification inhibitors on transformations of urea N in soils were studied by determining the effects of these compounds (10 μg/g of soil) on urea hydrolysis, ammonia volatilization. and production of ammonium, nitrite, and nitrate in soils incubated under aerobic conditions (30°C, 60% WHC) after treatment with urea (400 μg of urea N/g of soil). The inhibitors used (N-Serve, ATC, and CL-1580) had little, if any, effect on urea hydrolysis, but they retarded nitrification of the ammonium formed by urea hydrolysis and increased gaseous loss of urea N as ammonia. They also decreased the amount of (urea + exchangeable ammonium + nitrite + nitrate) — N found in urea-treated soils after various times. Two of the soils used accumulated substantial amounts of nitrite(> 160 μg of nitrite N/g of soil) when incubated under aerobic conditions after treatment with urea. Addition of nitrification inhibitors to these soils eliminated or substantially reduced nitrite accumulation and greatly retarded nitrate formation, but had little, if any, effect on the recovery of urea N as (urea + exchangeable ammonium + nitrite + nitrate + ammonia) — N after various times. This finding and other observations reported indicate that the “nitrogen deficits” observed in studies of urea N transformations in soils may not largely be due to gaseous loss of urea N through chemodenitrification and are at least partly due to volatilization and fixation of the ammonium formed by urea hydrolysis in soils. The work reported also indicates that N-Serve and other nitrification inhibitors may prove useful for reduction of the nitrite toxicity problems associated with the use of urea as a fertilizer but that application of such inhibitors in conjunction with fertilizer urea, when surface applied, may promote gaseous loss of urea N as ammonia.

Journal ArticleDOI
TL;DR: It is concluded that nitrite reduction is functionally associated with the electron transport arising from the light reactions of the chloroplast and this provides additional support for the localization of nitrite reductase in the chloroplasts.
Abstract: Methyl viologen and phenazine methosulfate (photosystem I electron acceptors), 3-(3,4-dichlorophenyl)-1, 1-dimethylurea (DCMU, electron-transport inhibitor), and methylamine (photophosphorylation uncoupler) were used to study the dependence of nitrite reduction on electron transport in chloroplasts.DCMU, methyl viologen, and phenazine methosulfate markedly inhibited, whereas methylamine stimulated NO(2) (-) reduction in isolated, intact spinach (Spinacia oleracea L.) chloroplasts. The addition of DCMU to leaf sections of spinach and corn, (Zea mays L. var. XL81), incubated with No(3) (-), caused no inhibition of nitrate reduction but inhibited nitrite reduction leading to the accumulation of NO(2) (-) in the light. The addition of methylamine to comparable leaf sections did not affect either nitrate or nitrite reduction.WE CONCLUDED THAT: (a) nitrite reduction is functionally associated with the electron transport arising from the light reactions of the chloroplast and this provides additional support for the localization of nitrite reductase in the chloroplast; (b) nitrite reduction is associated with photosystem I and ferredoxin is the most likely donor in leaf tissue; and (c) ATP is not involved directly in nitrite reduction. However, ATP synthesis, by regulating electron flow to photosystem I, can affect nitrite reduction in the light.


Journal ArticleDOI
TL;DR: In this paper, pork bellies were formulated to 0, 30, 60, 120, 170, or 340 mug of nitrite per g of meat and inoculated with Clostridium botulinum via pickle or after processing and slicing.
Abstract: Pork bellies were formulated to 0, 30, 60, 120, 170, or 340 mug of nitrite per g of meat and inoculated with Clostridium botulinum via pickle or after processing and slicing. Processed bacon was stored at 7 or 27 C and assayed for nitrite, nitrate, and botulinal toxin at different intervals. Nitrite levels declined during processing and storage. The rate of decrease was more rapid at 27 than at 7 C. Although not added to the system, nitrate was detected in samples during processing and storage at 7 and 27 C. The amount of nitrate found was related to formulated nitrite levels. No toxin was found in samples incubated at 7 C throughout the 84-day test period. At 27 C, via pickle, inoculated samples with low inoculum (210 C. botulinum per g before processing and 52 per g after processing) became toxic if formulated with 120 mug of nitrite per g of meat or less. Toxin was not detected in bacon formulated with 170 or 340 mug of nitrite per g of meat under these same conditions. Toxin was detected at all formulated nitrite levels in bacon inoculated via the pickle with 19,000 C. botulinum per g (4,300 per g after processing) and in samples inoculated after slicing. However, increased levels of formulated nitrite decreased the probability of botulinal toxin formation in bacon inoculated by both methods.

Journal ArticleDOI
TL;DR: The postulated intermediate of nitrite-myoglobin reaction, cysteine-nitrosothiol, was prepared and its antibacterial effect was tested on Salmonella strains, Streptococcus faecium, and spores and vegetative cells of Clostridium sporogenes.
Abstract: The postulated intermediate of nitrite-myoglobin reaction, cysteine-nitrosothiol, was prepared and its antibacterial effect was tested on Salmonella strains, Streptococcus faecium, and spores and vegetative cells of Clostridium sporogenes. Cysteine-nitrosothiol showed a higher inhibitory effect than nitrite. Preliminary results on the effect of simultaneous use of nitrite and cysteine on Clostridium sporogenes spores were also presented.

Journal ArticleDOI
08 Mar 1974-Nature
TL;DR: It has been suggested that co-administration of ascorbic acid with potentially nitrosatable drugs, and foods containing nitrite, may reduce the hazards associated with ingestion of these substances.
Abstract: THE dangers to health from nitrite in the environment generally, and its use in meat processing in particular, have been pointed out by several groups1–3. These dangers are associated with the production of nitrous acid in the acid environment of the stomach and the further reaction of this substance with naturally occurring and synthetic secondary and tertiary amines to form nitroso compounds which may be carcinogenic, mutagenic and cytotoxic. Ascorbic acid has been shown to effectively compete with amines for nitrous acid in vitro4 and it has been suggested that co-administration of ascorbic acid with potentially nitrosatable drugs, and foods containing nitrite, may reduce the hazards associated with ingestion of these substances4.

Journal ArticleDOI
TL;DR: The German sodium salicylate method for nitrate determination has been modified and improved by utilizing flocculating effect of the preservative HgCl 2 (1000 mg 1 −1 ) as discussed by the authors.

Journal ArticleDOI
TL;DR: The enzyme activities are inhibited on preincubation with either reduced pyridine nucleotide electron donor (NADPH or NADH), provided FAD is present, and the electron acceptors, nitrite and hydroxylamine, protect against this inactivation.

Journal ArticleDOI
TL;DR: In this paper, Nacyltryptophan derivatives with sodium nitrite under mildly acidic conditions were treated with the nitroso-group located at the indolic nitrogen, and the results showed that the nitrosamine with the group was replaced by the nitric acid.
Abstract: Treatment of N-acyltryptophan derivatives with sodium nitrite under mildly acidic conditions furnishes the nitrosamine with the nitroso-group located at the indolic nitrogen.

Journal ArticleDOI
TL;DR: It is concluded that E. coli K12 has alternative pathways for synthesizing glutamate, and because the K m of glutamate dehydrogenase for NH3 is 1·6 mM, a growth-limiting concentration of an inorganic nitrogen compound in the reservoir would be assimilated predominantly by the glutamine synthetase-glutamate synthase pathway.
Abstract: SUMMARY: Anaerobic continuous cultures of Escherichia coli strains Hfrc and K12-OR75 assimilated nitrite to produce 63·7 g dry mass/g-atom N. Washout occurred when these cultures were aerated, or when the dilution rate was above 0·05 h-1. Nitrite reductase, glutamate dehydrogenase and glutamine synthetase activities and cytochrome c 552 synthesis were derepressed when growth of strain OR75 was limited by the concentration of either nitrite or ammonia in the reservoir. Glutamate synthase activity was far less than glutamate dehydrogenase, but was highest when nitrite limited growth. These results indicate that enzymes which catalyse glutamate synthesis from inorganic nitrogen compounds are regulated in an interdependent manner, but that glutamine synthetase protein is unlikely to be the aporepressor for glutamate dehydrogenase synthesis in this organism. Possible reasons for apparently opposite regulatory mechanisms in E. coli and Klebsiella aerogenes are discussed in the context of the selective pressures which are applied to bacteria in continuous culture. We conclude that E. coli K12 has alternative pathways for synthesizing glutamate, and because the K m of glutamate dehydrogenase for NH3 is 1·6 mM, a growth-limiting concentration of an inorganic nitrogen compound in the reservoir would be assimilated predominantly by the glutamine synthetase-glutamate synthase pathway.

Journal ArticleDOI
TL;DR: In this article, the authors present evidence concerning the control of nitrate reductase in AQ-6 mutants and develop elements of an hypothesis relating the effects of blue light and ammonia.


Journal ArticleDOI
TL;DR: Effect of nitrate reduction on fermentation products of Clostridium perfringens was investigated in nutrient media containing glucose, and formation of hydrogen, equimolar to carbon dioxide, was ceased by nitrates reduction.
Abstract: Effect of nitrate reduction on fermentation products of Clostridium perfringens was investigated in nutrient media containing glucose. Butyrate, acetate, lactate, and ethanol were produced in the absence of nitrate. Addition of nitrate caused disappearance of butyrate and marked decrease in ethanol amounts as well as nitrite accumulation. Acetate was the main product in this case. Formation of hydrogen, equimolar to carbon dioxide, was ceased by nitrate reduction. Molar growth yield and growing rate of cells were not changed in nitrate reduction.