Growth of lithotrophic ammonia-oxidizing bacteria on hydroxylamine

Nitrosomonas europaea, Nitrosomonas nitrosa and Nitrosococcus oceanus were successfully grown on hydroxylamine. Significant cell yields were obtained in media containing ammonia supplemented with successive small additions of hydroxylamine. The molar growth yield on hydroxylamine, measured as formation of cell protein per unit of substrate oxidized, was found to be approximately twice that on ammonia. In respiration experiments, the oxygen consumption was 1.5 mol O2 per mol ammonia and 1.0 mol O2 per mol hydroxylamine oxidized to nitrite.