Ammonia stimulates growth and nitrite-oxidizing activity of .

The aim of this study was to obtain a nitrite-oxidizing bacterium with high nitrite oxidation activity for controlling nitrite levels. A nitrite-oxidizing bacterium, ZS-1, was isolated from the water of a coastal -rearing pond. The strain was identified as based on the phylogenetic analyses of the 16S ribosomal ribonucleic acid gene and sequence of ZS-1. Under aerobic condition, the nitrite-oxidizing activity of ZS-1 did not change considerably in the range of pH 7-9, but was strongly inhibited by lower (pH = 6) and higher (pH = 10) pH values. The optimum temperature range is 25-32 °C. Lower temperature made the adaptive phase of ZS-1 longer but did not affect its maximum nitrite oxidization rate. The nitrite-oxidizing activity of ZS-1 started to be inhibited by ammonia and nitrate when the concentrations of ammonia and nitrate reached 25 mg L and 100 mg L, respectively. The inhibition was stronger with higher concentration of ammonia or nitrate. The nitrite-oxidizing activity of ZS-1, however, was not inhibited by high concentration of nitrite (500 mg L). The nitrite-oxidizing activity of ZS-1 was increased by low ammonia concentration (1 mg L to 10 mg L).