Abstract
Effects of 2-amino-4-methyl-6-trichloromethyl-s-triazine (s-triazine) and nitrapyrin on ammonia oxidizing activity by Nitrosomonas europaea ATCC 25978 and N. sp. TK 794 which was recently isolated from soil, and nitrite oxidizing activity by Nitrobacter agilis ATCC 14123 were investigated by determining nitrite amount and their growth in the medium. One and 10.0μg/ml of the s-triazine and nitrapyrin significantly inhibited nitrite production by N. europaea ATCC 25978 and N. sp. TK 794 and simultaneously suppressed their growth, although N. sp. TK 794 was affected more strongly than N. europaea ATCC 25978. However, both the s-triazine and nitrapyrin did not inhibit nitrite oxidation by N. agilis ATCC 14123 at any concentrations tested (0.1 to 10.0μg/ml). These results suggest that Nitrosomonas may be one of the target bacteria of these inhibitors. In other words, the inhibitors may suppress the growth of Nitrosomonas, resulting in decreasing the ammonia-oxidizing activity.
