泉州西湖沉积物中硝化细菌的分布及其作用

摘要

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 l.lxl06-6.4×l06 cells per g of dry sediment which were higher than 4.2xl05-7.4xl05 cells per g of dry sediment of NOB (Paired Mest, 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 potentials (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.%比较研究泉州西湖沉积物中氨氧化细菌(AOB)和亚硝酸盐氧化细菌(NOB)的分布及氨氧化潜力和亚硝酸盐(NO2-)氧化潜力.结果表明:西湖沉积物中存在高浓度的有机质(OM)、总氮(TN)和氨氮.AOB生物量为1.1×106-6.4x 106个/g干土,显著高于NOB生物量4.2×105-7.4x 105个/g干土(配对t-检验,P＜0.05).对于NOB,硝化杆菌属(Nitrobacter)和硝化螺菌属(Nitrospira)同时存在于西湖沉积物中,以Nitrobacter为优势种群.AOB和NOB生物量的差异一定程度上导致西湖沉积物中氨氧化潜力显著高于NO2-氧化潜力(配对t-检验,P＜0.05),NO2-氧化过程成为硝化作用的限制步骤.另外,西湖沉积物中存在的较高浓度氨氮,一方面促进了AOB的生长和活性,导致较高速率的氨氧化过程,另一方面却对亚硝酸盐氧化过程产生选择性抑制,这也是导致NO2-氧化潜力较低的主要原因之一.