J. Groeneweg et al., AMMONIA OXIDATION IN NITROSOMONAS AT NH3 CONCENTRATIONS NEAR K-M - EFFECTS OF PH AND TEMPERATURE, Water research, 28(12), 1994, pp. 2561-2566
Nitrosomonas europaea from continuous pure cultures was incubated with
26.4 mu M NH3 (= 0.37 mg NH3-N l(-1)) at various NH4+ concentrations,
pH values and temperatures. Measured rates of nitrite formation were
significantly influenced by pH. Likewise unexpectedly, the maximum amm
onia oxidation rate occurred between pH 6.7 and 7.0. Temperature had a
n even stronger effect on the rate of ammonia oxidation than the avail
ability of NH3. It is concluded that the assumption of a strict depend
ence of the rate of ammonia oxidation on substrate concentration is an
unjustified oversimplification. Among the mechanisms which could expl
ain ammonium uptake and oxidation near or below pH 7.0, the formation
of NO from HNO2 is considered.