Confirmation of ‘aerobic denitrification’ in batch cultures, using gas chromatography and 15N mass spectrometry

Abstract

Because of a revival in the controversy surrounding [`]aerobic denitrification', especially in relation to Thiosphaera pantotropha, activity in aerobic batch cultures was evaluated using gas chromatography and mass spectrometry after the addition of 15N-labelled NH4+ and NO2-. Aerobic denitrifying activity in T. pantotropha was present, but only at about 10% of the originally-reported levels. The activity of [`]Pseudomonas denitrificans' was similar to previously-reported values. Alcaligenes faecalis showed significant aerobic denitrifying activity, producing almost equivalent amounts of N2 and N2O. An unidentified pseudomonad, isolate G4, presumably requires anoxia for enzyme activity as it did not denitrify aerobically, even though it has a constitutive denitrifying pathway.