Nitrate requirement for acetylene inhibition of nitrous oxide reduction in marine sediments

1989 ◽  
Vol 17 (2) ◽  
pp. 143-157 ◽  
Author(s):  
Jennifer M. Slater ◽  
Douglas G. Capone
Keyword(s):  
Nitrous Oxide ◽  
Marine Sediments ◽  
Oxide Reduction ◽  
Acetylene Inhibition ◽  
Nitrous Oxide Reduction

scholarly journals Effects of Specific Inhibitors on Anammox and Denitrification in Marine Sediments

2007 ◽  
Vol 73 (10) ◽  
pp. 3151-3158 ◽  
Author(s):  
Marlene Mark Jensen ◽  
Bo Thamdrup ◽  
Tage Dalsgaard
Keyword(s):  
Nitrous Oxide ◽  
Marine Sediments ◽  
Decay Constant ◽  
Metabolic Inhibitors ◽  
Anammox Bacteria ◽  
Natural Environments ◽  
Ammonium Oxidation ◽  
Oxide Reduction ◽  
Nitrous Oxide Reduction ◽  
Isotope Technique

ABSTRACT The effects of three metabolic inhibitors (acetylene, methanol, and allylthiourea [ATU]) on the pathways of N2 production were investigated by using short anoxic incubations of marine sediment with a 15N isotope technique. Acetylene inhibited ammonium oxidation through the anammox pathway as the oxidation rate decreased exponentially with increasing acetylene concentration; the rate decay constant was 0.10 ± 0.02 μM−1, and there was 95% inhibition at ∼30 μM. Nitrous oxide reduction, the final step of denitrification, was not sensitive to acetylene concentrations below 10 μM. However, nitrous oxide reduction was inhibited by higher concentrations, and the sensitivity was approximately one-half the sensitivity of anammox (decay constant, 0.049 ± 0.004 μM−1; 95% inhibition at ∼70 μM). Methanol specifically inhibited anammox with a decay constant of 0.79 ± 0.12 mM−1, and thus 3 to 4 mM methanol was required for nearly complete inhibition. This level of methanol stimulated denitrification by ∼50%. ATU did not have marked effects on the rates of anammox and denitrification. The profile of inhibitor effects on anammox agreed with the results of studies of the process in wastewater bioreactors, which confirmed the similarity between the anammox bacteria in bioreactors and natural environments. Acetylene and methanol can be used to separate anammox and denitrification, but the effects of these compounds on nitrification limits their use in studies of these processes in systems where nitrification is an important source of nitrate. The observed differential effects of acetylene and methanol on anammox and denitrification support our current understanding of the two main pathways of N2 production in marine sediments and the use of 15N isotope methods for their quantification.

Sulfide alleviation of acetylene inhibition of nitrous oxide reduction by Flexibacter Canadensis

1992 ◽  
Vol 38 (2) ◽  
pp. 143-148 ◽  
Author(s):  
Alison M. Jones ◽  
Roger Knowles
Keyword(s):  
Nitrous Oxide ◽  
Pseudomonas Stutzeri ◽  
Sulfide Concentration ◽  
Oxide Reduction ◽  
Acetylene Inhibition ◽  
Experimental Conditions ◽  
Nitrous Oxide Reduction ◽  
Pure Cultures ◽  
Dissolved Sulfide ◽  
Key Words Denitrification

The role of sulfide in the relief of acetylene inhibition of nitrous oxide reduction by Flexibacter canadensis was studied. In this organism, the reversal of acetylene inhibition of nitrous oxide reduction is correlated with a 90% decrease in the dissolved sulfide concentration. The fate of this sulfide is not known, since there was no concomitant increase in acid-soluble sulfide and volatile sulfur compounds were not detectable by flame photometric gas chromatography. Of the other sulfur-containing compounds tested (sulfate, sulfite, thiosulfate, cysteine, methionine, dithionite, dithionate, and glutathione), only cysteine relieved the acetylene block of nitrous oxide reduction by F. canadensis. Under similar experimental conditions, other denitrifiers tested (Azospirillum brasilense, Pseudomonas stutzeri, and a Flavobacterium isolate) failed to reduce nitrous oxide in the presence of sulfide and an inhibitory concentration of acetylene. It is concluded that both biological and abiological factors contribute to the sulfide relief of acetylene inhibition of nitrous oxide by pure cultures of F. canadensis. Key words: denitrification, nitrous oxide, acetylene, sulfide, Flexibacter canadensis.

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.

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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