Distribution and role of nitrifying bacteria in the sediments of Xihu Lake in Quanzhou

Abstract:

The distribution of ammonia oxidizing bacteria (AOB) and nitrite oxidizing bacteria (NOB) and the potentials of ammonia and nitrite (NO2?) oxidation were studied in the sediments of Xihu Lake in Quanzhou. The high concentrations of organic matter (OM), total nitrogen (TN) and ammonia existed in the sediments of Xihu Lake. The number of AOB were 1.1×106?6.4×106 cells per g of dry sediment which were higher than 4.2×105?7.4×105 cells per g of dry sediment of NOB (Paired t-test, P<0.05). With regard to NOB, the two genera of Nitrobacter and Nitrospira coexisted in the sediments of Xihu Lake, and Nitrobacter were the dominant NOB. The difference of AOB and NOB number resulted to some extent in that ammonia oxidation potentials were significantly higher than NO2? oxidation poten-tials (Paired t-test, P<0.05), indicating that NO2? oxidation was the rate-limiting step in nitrification. In addition, the high ammonia concentrations in sediment of Xihu Lake which accelerated ammonia oxi-dation but selectively inhibited NO2? oxidation, also lead to low NO2? oxidation potentials.