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Updated: Aug 14, 2026

Measurement of the Potential Rates of Dissimilatory Nitrate Reduction to Ammonium Based on 14NH4+/15NH4+ Analyses via Sequential Conversion to N2O
Published on: October 7, 2020
Inhibition of chemoautotrophic nitrification by sodium chlorate and sodium chlorite: a reexamination
1Department of Microbiology, Macdonald Campus, McGill University, Ste. Anne de Bellevue, Quebec, Canada H9X IC0.
Abstract:
The oxidation of NH(4) by Nitrosomonas europaea was insensitive to 10 mM NaClO(3) (sodium chlorate) but was strongly inhibited by NaClO(2) (sodium chlorite; K(i), 2 muM). The oxidation of NO(2) by Nitrobacter winogradskyi was inhibited by both ClO(3) and ClO(2) (K(i) for ClO(2), 100 muM). N. winogradskyi reduced ClO(3) to ClO(2) under both aerobic and anaerobic conditions, and as much as 0.25 mM ClO(2) was detected in the culture filtrate. In mixed N. europaea-N. winogradskyi cell suspensions, the oxidation of both NH(4) and NO(2) was inhibited in the presence of 10 mM ClO(3) after a 2-h lag period, despite the fact that, under these conditions, ClO(2) was not detected in the filtrate. The data are consistent with the hypothesis that, in mixed culture, NH(4) oxidation is inhibited by ClO(2) produced by reduction of ClO(3) by the NO(2) oxidizer. The use of ClO(3) inhibition of NO(2) oxidation in assays of nitrification by mixed populations necessitates cautious interpretation unless it can be shown that the oxidation of NH(4) is not affected.
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