Showing papers on "Nitrite published in 1968"

Acetate Assimilation by Nitrobacter agilis in Relation to Its “Obligate Autotrophy”

Abstract: Acetate (1 to 10 mm) had no effect on the rate of nitrite oxidation or exponential growth by Nitrobacter agilis. However, acetate-1-(14)C and -2-(14)C were both assimilated by growing cultures, and acetate carbon contributed 33 to 39% of newly synthesized cell carbon. Carbon from acetate was incorporated into all of the major cell constituents, including most of the amino acids of cell protein and poly-beta-hydroxybutyrate (PHB). Cultures grown in the presence of acetate showed a significant increase in turbidity, attributable in part to protein synthesis and the accumulation of PHB in the "post-exponential phase," when the supply of nitrite was completely exhausted. Cell suspensons of N. agilis assimilated acetate in the absence of bicarbonate and even in the absence of nitrite. However, the addition of nitrite increased the rate of acetate assimilation by cell suspensions. The distribution of (14)C-acetate incorporated by cell suspensions was qualitatively similar to that found with growing cultures. Cell suspensions of N. agilis slowly oxidized acetate to CO(2). Addition of nitrite suppressed CO(2) production from acetate but increased the assimilation of acetate carbon into cell material. N. agilis contained all the enzymes of the tricarboxylic acid cycle. Growth of N. agilis in the presence of acetate did not significantly affect the levels of the enzymes of the tricarboxylic acid cycle, but did result in a 100-fold increase in the specific activity of isocitratase. In contrast, carboxydismutase was partially repressed. N. agilis was grown heterotrophically through seven transfers on a medium containing acetate and casein hydrolysate. The addition of nitrite increased the rate of heterotrophic growth. Heterotrophically grown organisms still retained their ability to grow autotrophically with nitrite. However, these organisms oxidized nitrite at a slower rate. Organisms from autotrophic and heterotrophic cultures were analyzed to determine the mean guanine plus cytosine content of their deoxyribonucleic acid; in both cases this mean was 61.2 +/- 1%. We concluded that N. agilis is not an obligate autotroph; it appears to be a facultative autotroph which resembles the novel facultative autotroph, Thiobacillus intermedius, very closely.

Nitrogen-15: microbiological alteration of abundance.

Abstract: The abundance of N15 relative to N14 is significantly altered during experiments in vitro in which nitrate and nitrite are microbiologically reduced to nitrogen gas. In all studies to date, N14O3-and N14O2-species have been preferentially reduced. This selectivity has a complex dependence on conditions in the medium. The results are not only relevant to natural variations in N15 relative to N14 but should be seriously considered during N15 tracer studies in soils.

Effect of Sodium Nitrite, Sodium Chloride, and Sodium Nitrate on Germination and Outgrowth of Anaerobic Spores

Abstract: The effects of meat-curing agents on germination and outgrowth of putrefactive anaerobe 3679h (PA 3679h) spores were studied in microcultures. Nitrite concentrations up to 0.06% at p H 6.0 or between 0.8 and 1% at p H 7.0 allowed emergence and elongation of vegetative cells but blocked cell division. The newly emerged cells then lysed. With more than 0.06% nitrite at p H 6.0 or more than 0.8 to 1% at p H 7.0, the spores lost refractility and swelled, but vegetative cells did not emerge. Even as much as 4% nitrite failed to prevent germination (complete loss of refractility) and swelling of the spores. Sodium chloride concentrations above 6% prevented complete germination (i.e., the spores retained a refractile core). In the presence of 3 to 6% sodium chloride, most of the spores germinated and produced vegetative cells, but cell division was often blocked. Sodium nitrate had no apparent effect on germination and outgrowth at concentrations up to 2%. Images

Formation of Nitric Oxide Myoglobin: Mechanisms of the Reaction with Various Reductants

Abstract: SUMMARY– The concentration, temperature and pH dependences of the formation of nitric oxide myoglobin (NOMb) from metmyoglobin nitrite (MetMb·NO2) were determined for nitrite and the reductants, ascorbic acid, cysteine, hydro-quinone, nicotinamide adenine dinucleotide (NADH) and glyceraldehyde. The reaction for all reductants except glyceraldehyde involves the production of a nitroso-reductant intermediate which breaks down to release nitric oxide. The latter forms a nitric oxide metheme complex (Fe+++) which is then reduced to the ferrous state (Fe++). With cysteine and NADH there is a second pathway which probably involves the direct reduction of MetMb NO2. Ascorbate and hydro-quinone form nitroso intermediates that are stabilized in alkali. The effects of oxygen, ethylenediaminetetraacetic acid and cytochrome c on the reaction were determined. Oxygen slows or inhibits the reaction, while the latter two have no effect on the reaction as studied.

Role of Curing Agents in the Preservation of Shelf-stable Canned Meat Products

Abstract: Experiments were conducted to gain a better understanding of the mechanism by which sodium chloride, sodium nitrate, and sodium nitrite supplement the action of heat in preserving canned cured meat products. Heated spores of putrefactive anaerobe 3679h were less tolerant of all three curing agents in the outgrowth medium than were unheated spores. When the curing agents were added to the heating menstruum, but not to the outgrowth medium, sodium chloride and sodium nitrate tended to protect the spores against heat injury, but sodium nitrite did not. When the spores were both heated and cultured in the presence of the curing agents: (i) nitrate and salt increased the apparent heat resistance at low concentrations (0.5 to 1%) but decreased it at concentrations of 2 to 4%; (ii) nitrite was markedly inhibitory, especially at pH 6.0. At the normal pH of canned luncheon meats (approximately 6.0), nitrite appears to be the chief preservative agent against spoilage by putrefactive anaerobes.

Comparative Study of Factors Influencing the Action of Corrosion Inhibitors for Mild Steel in Neutral Solution: III. Sodium Nitrite

Abstract: The action of sodium nitrite as a corrosion inhibitor for mild steel in neutral aqueous solution has been studied in relation to the surface preparation of the steel, the presence of aggressive salts in the solution, and temperature.Surface preparation of mild steel has little effect on the minimum concentration of nitrite required for protection in distilled water. In solutions containing aggressive anions a linear relation exists between the logarithm of the nitrite concentration and the logarithm of the maximum concentration of aggressive anion that will permit inhibition. In solutions of low nitrite concentration the order of aggressiveness of anions is sulphate > chloride > nitrate; the order changes with increase in nitrite concentration. Corrosion in non-inhibiting nitrite/aggressive anion solutions is frequently of a severely localised form. A 5-fold increase in nitrite requirement for inhibition of abraded mild steel in distilled water is found between 5° and 70°, with a further large, ra...

The Effect of Carbon Dioxide Concentration and Buffer System on Nitrate and Nitrite Assimilation by Dunaliella tertiolecta

Abstract: SUMMARY: Dunaliella tertiolecta required carbon dioxide in substrate concentrations (1.75%, v/v) to assimilate either nitrate or nitrite at maximum rates in light. The addition of glucose, glycerol, acetate, pyruvate or α-ketoglutarate did not remove the requirement for carbon dioxide. The rates of nitrate and nitrite assimilation in light depended upon the buffer system used. The lowest rates of nitrate assimilation, 1.3 μmoles/hr/mg. chlorophyll, were observed in 0.05 M-phosphate buffer (pH 7.6) and the highest, 13.7 μmoles/hr/mg. chlorophyll, in 0.05 M-Tricine buffer (pH 7.6). Nitrite assimilation was lowest, 7.5 μmoles/hr/mg. chlorophyll, in 0.05 M-phosphate (pH 7.6) while the highest rates, 18.7 μmoles/hr/mg. chlorophyll, were observed in 0.05 M-Tricine (pH 8.6). The low rate of assimilation of nitrate and nitrite in 0.05 M-phosphate buffer (pH 7.6) was increased by diluting the buffer to 0.005 M, at this concentration the rate in phosphate buffer was comparable to that in tris or Tricine buffers at the same pH values. Buffer type had little effect on either nitrate or nitrite assimilation in the dark. There was no evidence with any buffer system used for the evolution of extra oxygen associated with nitrate or nitrite assimilation in the light. These results provide further evidence for the existence of two independent systems of nitrate reduction, one within and the other without the chloroplast. In addition, they indicate that in Dunaliella tertiolecta the enzyme system which fixes carbon dioxide is unlikely to be the rate-limiting step in photosynthesis.

Nitrite Formation from Hydroxylamine and Oximes by Pseudomonas aeruginosa

Abstract: Nitrite was formed from hydroxylamine and several oximes by intact cells and extracts of Pseudomonas aeruginosa The activity was induced by the presence of oximes in the culture medium Nitroalkanes were not intermediates in the conversion of acetaldoxime, acetone oxime, or butanone oxime to nitrite, since nitromethane inhibited the formation of nitrite from the nitro compounds but not from the corresponding oximes The oxime apparently functions as a constant source of hydroxylamine during growth of the bacterium Hydroxylamine at low concentration was converted stoichiometrically to nitrite by extracts of the bacterium; high concentrations were inhibitory Nicotinamide adenine dinucleotide phosphate, oxygen, and other unidentified cofactors were necessary for the reaction Actively nitrifying extracts possessed no hydroxylamine-cytochrome c reductase activity Hyponitrite, nitrous oxide, and nitric oxide were not metabolized

Evidence for a Role of Calcium in Nitrate Assimilation in Wheat Seedlings

Abstract: Severely Ca-deficient Triticum aestivum L. seedlings accumulated high levels of nitrite and moderate levels of nitrate and organic nitrogen, but contained unaltered levels of hydroxylamine. Nitrite accumulation was not related to molybdenum deficiency, or altered cellular pH. Nitrate reductase was decreased by Ca deficiency, apparently by repression of enzyme synthesis from accumulated nitrite and not by inhibition of enzyme activity. Nitrite reductase and NADP diaphorase activities were not affected by Ca deficiency, and Ca did not restore activity to nitrite reductase inactivated by cyanide. The results indicated that the role of Ca is in intracellular transport of nitrite and not in induction or activity of enzymes.

Nitrite-induced Germination ofPutrefactive Anaerobe 3679hSpores1

Abstract: Sodium nitrite alone has been shown to stimulate germination of PA 3679h spores. The process was accelerated by using increased concentrations of sodium nitrite, a low pH, and a high temperature of incubation. At low concentrations of nitrite (0.01 to 0.2%), the delay of 36 to 48 hr occurred before germination commenced at 37 C. However, with 3.45% nitrite at 45 C and pH 6.0, most of the spores germinated within 1 hr. At pH 7.0, the germination rate decreased markedly, and at pH 8.0 it was nil. The greatest acceleration in germination rate occurred near 60 C. Hydroxylamine was completely inhibitory to nitrite-induced germination. Sodium nitrite, in turn, inhibited germination by l-alanine, the degree of inhibition being influenced by nitrite concentration and pH.

Heterotrophic nitrification by Pseudomonas aeurginosa.

Abstract: Several soil bacteria and fungi produce nitrite when provided with acetaldoxime. Nitrite formation by one isolate, identified as a strain of Pseudomonas aeruginosa, is not directly linked to growth but rather proceeds mainly after the active growth period. The added oxime-nitrogen is converted completely to nitrite, and nitrate is not formed. Extracts of the bacterium generate nitrite, but not nitrate, more rapidly from nitroethane than from the added oxime. The enzyme system catalyzing the formation of nitrite in oxime solutions is soluble and inducible, whereas the enzyme catalyzing the release of equimolar quantities of nitrite and acetaldehyde from nitroethane is constitutive. The slow rate of nitrite production when the enzyme preparation is provided with acetaldoxime is not markedly increased by added cofactors. The soluble enzymes also generate nitrite when incubated with several aliphatic and alicyclic oximes and nitro compounds. Nitroethane is not formed from acetaldoxime. The possible mechanism of this nitrification reaction catalyzed by a heterotrophic microorganism is discussed.

Triplet State of the Nitrite Molecule–Ion

Abstract: The absorption spectra of aqueous solutions of a number of nitrite complexes exhibit a common absorption band at ∼ 23 kK. This absorption band is responsible for the color of those metal nitrites in which the cation is colorless. This band is assigned as the T1 ← S0 transition of the nitrite molecule–ion. The intensification of the T1 ← S0 transition in the heavier‐metal nitrites is a spin–orbit enhancement brought about by the heavy‐metal cation. Equilibrium constants for Cd(II), Pb(II), and Tl(I) nitrite complexes‐ and extinction coefficients for the 23‐kK band have been elicited. The 23‐kK band is the reverse absorption to the phosphorescence emission; the T1 → S0 radiative lifetimes correlate with those calculated from oscillator strengths of the 23‐kK absorption band.

Nitrite-induced Germination of Putrefactive Anaerobe 3679h Spores

Abstract: Sodium nitrite alone has been shown to stimulate germination of PA 3679h spores. The process was accelerated by using increased concentrations of sodium nitrite, a low pH, and a high temperature of incubation. At low concentrations of nitrite (0.01 to 0.2%), the delay of 36 to 48 hr occurred before germination commenced at 37 C. However, with 3.45% nitrite at 45 C and pH 6.0, most of the spores germinated within 1 hr. At pH 7.0, the germination rate decreased markedly, and at pH 8.0 it was nil. The greatest acceleration in germination rate occurred near 60 C. Hydroxylamine was completely inhibitory to nitrite-induced germination. Sodium nitrite, in turn, inhibited germination by l-alanine, the degree of inhibition being influenced by nitrite concentration and pH.

Fine structure and the localization of the nitrite oxidizing system inNitrobacter winogradskyl

Abstract: The existence of a membrane system located at one of the poles of the cell is confirmed in the case ofNitrobacter winogradskyi. Additional information on the structure of this system is presented. Elementary particles with diameters of 90 – 100 A are embedded on a layer of membrane protein. Identification of the membrane system as the location of nitrite oxidation was achieved by a combination of differential spectrophotometry and electron microscopic study of membrane fragments separated by density gradient centrifugation. The cytochrome chain responsible for nitrite oxidation appears to be located in fragments of the membrane system.

The effect of iron supply on the activity of nitrate and nitrite reduction in green algae

Abstract: An improved supply of iron, produced by an addition of EDTA to the culture medium, specifically increases the reduction of nitrite by green algae, whereas it has no influence on the reduction of nitrate to nitrite. Correspondingly, growth of the algae under iron-deficient conditions results in an inhibition of only nitrite reduction.

Charge Distribution of the NO2‐ Radical in Ferroelectric Sodium Nitrite

Abstract: The 14N nuclear quadrupole resonance spectrum of ferroelectric sodium nitrite is interpreted to yield the charge distribution of the nitrite radical. Contributions to the electric field gradient due to lattice changes are estimated by performing a lattice sum, while the local electrons are treated using the approximations of the Townes and Dailey theory. Occupation numbers for the N–O sigma‐ and pi‐bond wavefunctions are obtained, and the effective charge on the nitrogen is deduced. The latter quantity is found to be very close to zero.

Purification and Properties of Peroxidase from Nitrosomonas europaea

Abstract: Peroxidase from the obligate chemosynthetic bacterium Nitrosomonas europaea was purified 1,500-fold, and its properties were examined. The enzyme had a molecular weight of 53,000 and exhibited characteristic absorption maxima at 410, 524, and 558 mμ. The optimal pH and temperature were 7.5 and 44 C, respectively. The peroxidase reaction had an energy of activation of 5,850 cal/mole and required a primary substrate (H2O2) concentration of 7 × 10−6m to proceed at half maximal velocity (Km). Reduced cytochrome, c,p-phenylenediamine and pyrogallol acted as hydrogen donors to the purified peroxidase-H2O2 complex. Conditions most suitable for the chemical oxidation of ammonium by H2O2 were determined. The reaction was rapid and produced nitrite but no nitrate. Hydroxylamine was not detected as an intermediate, but it could substitute for ammonium in the system. Neither the rate nor the extent of these reactions was influenced by purified peroxidase, and no evidence was obtained to support a conclusion that the enzyme performs a vital role in the transformation of ammonium to nitrite by N. europaea.