Effects of sulfide and acetylene on nitrous oxide reduction by soil and by Pseudomonas aeruginosa

1979 ◽  
Vol 25 (10) ◽  
pp. 1133-1138 ◽  
Author(s):  
Tat-Yee Tam ◽  
Roger Knowles
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Nitrous Oxide ◽  
Sodium Sulfide ◽  
Sodium Thiosulfate ◽  
Cell Suspensions ◽  
Inhibition Assay ◽  
Sterile Soil ◽  
Washed Cell ◽  
Complete Reduction ◽  
Nitrous Oxide Reduction

The production and reduction of nitrous oxide (N2O) after the addition of N2O, nitrite (NO2−), or nitrate (NO3−) was studied in non-sterile soil, in sterilized soil inoculated with Pseudomonas aeruginosa, and in washed cell suspensions of this organism. Sodium sulfide (8 μmol S2− mL−1 or g−1) inhibited N2O reduction markedly in cell suspensions and also in soil, an effect which may cause sulfidic habitats to act as sources of N2O. Sodium thiosulfate (up to 64 μmol S2O32− g−1) showed no such effect. Acetylene (0.02 atm C2H2) completely inhibited the reduction of N2O by soil, but the combination of C2H2 with 8 μmol S2− g−1 permitted the complete reduction of 2 μmol added N2O g−1 within 3 days under the most favourable conditions. Under the same conditions, 8 μmol S2O32− g−1 permitted complete reduction of the N2O within 6 days. The rate of such reduction of N2O was decreased, but not inhibited completely, by raising the C2H2 concentration to 0.11 atm. The data have important implications for the effectiveness of the C2H2 inhibition assay of denitrification in highly anaerobic environments.

Denitrifïcation in Flexibacter canadensis

1990 ◽  
Vol 36 (6) ◽  
pp. 430-434 ◽  
Author(s):  
Alison M. Jones ◽  
Roger Knowles
Keyword(s):  
Nitrous Oxide ◽  
Sodium Sulfide ◽  
Electron Acceptors ◽  
Inhibition Assay ◽  
Oxide Reduction ◽  
Acetylene Inhibition ◽  
Gram Negative ◽  
Nitrous Oxide Reduction ◽  
Pure Cultures ◽  
Gliding Bacterium

Denitrifïcation was studied in pure cultures of Flexibacter canadensis (ATCC 29591), a Gram-negative gliding bacterium found in soil. Flexibacter canadensis was capable of using nitrate, nitrite, and nitrous oxide as terminal electron acceptors for growth. Sodium sulfide (200 μM) inhibited all of the nitrogen oxide reductases, but only temporarily. Acetylene (4 kPa) inhibited nitrous oxide reduction but did not affect the reduction of either nitrate or nitrite. However, sulfide (100 and 200 μM) alleviated the acetylene block and permitted reduction of nitrous oxide in the presence of 4 kPa acetylene. These data may have important implications regarding the use of the acetylene inhibition assay for measuring denitrifïcation rates in highly anaerobic, sulfidic environments. Key words: Flexibacter canadensis, denitrification, N2O reductase, sulfide, acetylene.

Production of nitrous oxide by Nitrosomonas europaea: effects of acetylene, pH, and oxygen

1984 ◽  
Vol 30 (11) ◽  
pp. 1397-1404 ◽  
Author(s):  
Russell K. Hynes ◽  
Roger Knowles
Keyword(s):  
Nitrous Oxide ◽  
Liquid Culture ◽  
Nitrosomonas Europaea ◽  
Cell Suspensions ◽  
Similar Response ◽  
Sterile Soil ◽  
Total N ◽  
Aerobic Conditions ◽  
Liquid Suspension ◽  
Aerobic Cell

Aerobic cell suspensions of Nitrosomonas europaea oxidized ammonium [Formula: see text] to nitrous oxide (N2O) and nitrite [Formula: see text], and exogenous [Formula: see text] in the presence or absence of [Formula: see text] did not stimulate N2O formation. Acetylene (C2H2) inhibited the production of [Formula: see text] and N2O from [Formula: see text] but not from hydroxylamine (NH2OH). The total amount of N2O formed in air was proportional to the amount of [Formula: see text] oxidized; however, the total N2O N formed as a percentage of [Formula: see text] N formed varied very little (0.05–0.15%) over the range of [Formula: see text] concentrations examined (0.05–20.4 mM). Rates of production of N2O and [Formula: see text] showed similar response to pH over the range of 5.4–9.5, with maxima at pH 8.5. Anaerobically, five times more N2O was formed than under aerobic conditions. The highest rates of anaerobic N2O formation were observed in the presence of [Formula: see text] and [Formula: see text] combined (2 and 1 mM, respectively) and C2H2 reduced this rate of N2O formation to that observed with 1 mM[Formula: see text] alone in the presence or absence of C2H2. The presence of the [Formula: see text] oxidizer Nitrobacter winogradskyi had no effect on the formation of N2O by Ns. europaea either in liquid culture or in sterile soil. However, the presence of sterile soil as a suspending matrix increased by 10-fold the production of N2O, and broadened the range of O2 concentrations under which relatively high rates of N2O production occurred. Maximum N2O production by Ns. europaea occurred at 0.75 kPa O2 in liquid suspension and at 2.5 kPa O2 in sterile soil.

DENITRIFICATION, DENITRIFYING BACTERIA, AND IRON REDUCTION IN A SOIL SUPPLEMENTED WITH SULFIDE AND ACETYLENE

1986 ◽  
Vol 66 (4) ◽  
pp. 633-639 ◽  
Author(s):  
ANNE M. ADKINS ◽  
ROGER KNOWLES
Keyword(s):  
Nitrous Oxide ◽  
Iron Reduction ◽  
Enrichment Culture ◽  
Denitrifying Bacteria ◽  
Sterile Soil ◽  
Culture Methods ◽  
Untreated Soil ◽  
Nitrous Oxide Reduction ◽  
Key Words Denitrification ◽  
Nitrate And Nitrite

Populations of denitrifying bacteria were estimated using MPN enrichment culture methods with nitrate, nitrite, and nitrous oxide (N2O) as electron acceptors. Nitrate and nitrite respirers predominated in untreated soil, and anaerobic preincubation with glucose and nitrate stimulated nitrate respirers 10-fold. During subsequent incubation with N2O and various combinations of acetylene (C2H2) and sulfide the numbers of nitrate and nitrite reducers decreased, and N2O reducers increased in treatments in which N2O reduction occurred. In the presence of N2O and C2H2 without sulfide there was no reduction of N2O and no change in the N2O-utilizing population. Incubation with N2O, C2H2, and sulfide caused a marked enrichment of N2O reducers in the denitrifying population. The addition of sulfide to anaerobic non-sterile or sterile soil caused an increase in reduced iron (Fe2+) and there was a relatively rapid conversion of free to acid-soluble sulfide. Key words: Denitrification, denitrifiers, sulfide, iron reduction, nitrous oxide reduction

Absence of storage products in cultures of Pseudomonas aeruginosa grown with excess carbon or nitrogen

1968 ◽  
Vol 14 (6) ◽  
pp. 627-631 ◽  
Author(s):  
R. M. MacKelvie ◽  
J. J. R. Campbell ◽  
Audrey F. Gronlund
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Nitrogen Source ◽  
Cell Suspensions ◽  
Excess Carbon ◽  
Washed Cell ◽  
Keto Acids ◽  
Limiting Nutrient ◽  
Storage Products ◽  
Production Of Ammonia

Pseudomonas aeruginosa failed to accumulate carbohydrate, lipid, including poly-β-hydroxybutyrate, or polyphosphate when grown under conditions normally favorable for the deposition of these reserve materials. Washed cell suspensions prepared from cultures grown under conditions of limiting nitrogen, limiting carbon, or excess of both exhibited immediate and linear production of ammonia when starved. When glucose-U-14C was added to a 24-h-culture, growing in a nitrogen-limited medium, the radioactivity was largely recovered in keto acids which accumulated in the growth supernatant. Exhaustion of the limiting nutrient during growth resulted in the degradation of ribosomes regardless of whether the nutrient was the carbon or nitrogen source.

Reversal of succinate-mediated catabolite repression of alkylsulfatase in Pseudomonas aeruginosa by 2,4-dinitrophenol and by sodium malonate

1978 ◽  
Vol 24 (12) ◽  
pp. 1567-1573 ◽  
Author(s):  
J. W. Fitzgerald ◽  
L. C. Kight-Olliff ◽  
G. J. Stewart ◽  
N. F. Beauchamp
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Induction Period ◽  
Sodium Succinate ◽  
Cell Suspensions ◽  
Atp Content ◽  
Succinate Oxidation ◽  
Sodium Malonate ◽  
Atp Levels ◽  
Sodium Malate ◽  
Stimulation Of

The Kreb's cycle intermediates and related metabolites (e.g., acetate) repressed the induced synthesis of alkylsulfatase in resting cell suspensions of Pseudomonas aeruginosa. At concentrations which caused substantial repression, sodium succinate as well as sodium malate, fumarate, and α-ketoglutarate were oxidized to yield consistently high levels of ATP throughout the induction period. Sodium oxalacetate which was markedly less effective as a metabolite repressor generated high ATP levels only during the first 2 h of the induction period. The addition of 2,4-dinitrophenol or sodium malonate to cell suspensions containing the inducer (sodium hexan-1-yl sulfate) and succinate overcame repression of alkylsulfatase formation and resulted in a reduction in the ATP content to levels found in cells exposed only to inducer. An apparent stimulation of alkylsulfatase induction occurred in the absence of succinate when cells were incubated with 2,4-dinitrophenol and inducer. In this case, the ATP content of the cell suspension fell to levels substantially below those occurring as a result of inducer catabolism. Collectively, these data suggest that the effectiveness of succinate as a metabolite repressor is related to the ATP levels generated as a consequence of succinate oxidation.

Release of nitrous oxide (N2O) from denitrifying activated sludge caused by H2S-containing wastewater: quantification and application of a new mathematical model

1998 ◽  
Vol 38 (1) ◽  
pp. 237-246 ◽  
Author(s):  
Barbara Schönharting ◽  
Ruxandra Rehner ◽  
Jörg W. Metzger ◽  
Karlheinz Krauth ◽  
Manfred Rizzi
Keyword(s):  
Mathematical Model ◽  
Nitrous Oxide ◽  
Hydrogen Sulfide ◽  
Activated Sludge ◽  
Sulfide Concentration ◽  
Oxide Reduction ◽  
Strong Inhibition ◽  
Wide Range ◽  
Nitrous Oxide Reduction ◽  
Denitrification Process

A new mathematical model is presented which describes the denitrification process by dynamic material balance equations. In this approach the kinetic rate expressions of the single denitrification steps and the observed strong inhibition of nitrate on nitrite and nitrous oxide reduction are based exclusively on fundamental enzyme kinetics. This allows a prediction of the denitrification process in a wide range of wastewater-relevant nitrate concentrations. The model was successfully applied to the description of the kinetic behavior of a standardized denitrifying activated sludge system. Furthermore the experimentally investigated influence of hydrogen sulfide was quantified by extending the model with a non-competitive inhibition mechanism involving all steps of the denitrification process. The inhibitory effect was related to the free membrane-permeable hydrogen sulfide concentration. This means that the extent of its inhibition depends additionally on the pH-value. Even very low hydrogen sulfide concentrations lead to a strong inhibition of nitrous oxide reduction and therefore to a high release of nitrous oxide from wastewater treatment plants.

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