三氯生及其降解中间产物对活性污泥中微生物群落变化和硝化反硝化功能基因的影响

三氯生（TCS）对活性污泥中氮循环和微生物群落的长期影响尚不清楚.在长期运行185 d的序批式反应器（SBR）进水中添加100 g·L^-1的TCS,探讨了TCS在活性污泥中的转化特性及其对活性污泥的生长、硝化反硝化性能及关键氮代谢功能基因和微生物群落结构的影响.添加TCS的反应器中硝酸盐浓度为3.80～9.11 mg·L^-1,略低于不添加TCS的空白组(6.66～9.72 mg·L^-1),说明其硝化作用被减弱.随着驯化时间的延长，硝化作用逐渐恢复. TCS在活性污泥迁移转化过程中总共检测出12种代谢中间产物，推导出4种迁移转化路径.添加TCS后，对TCS有潜在降解效能的细菌的相对丰度明显增加，如：Flavobacteriales和Myxococcales目，分别为2.95%～9.07%（第0～185 d）和2.01%～4.53%（第0～90 d）.与硝化作用有关的菌属，如：Nitrosovibrio、Nitrosomonas（氨氧化菌，AOB）和Nitrospira（亚硝酸盐氧化菌，NOB）的相对丰度急剧减少，分别为0....

Shifts in Microbial Community and Variation in Functional Genes for Nitrification and Denitrification in Activated Sludge Affected by Triclosan and Its Transformed Intermediates

Triclosan(TCS)is a typical pharmaceutical and personal care product (PPCPs), which widely exists in wastewater treatment plants (WWTPs). However, the long-term effects of TCS on the nitrogen cycle and microbial community in activated sludge remain clear. To examine the transformation characteristics of TCS in activated sludge and its effects on growth, nitrification, and denitrification performance, key nitrogen metabolism genes and the microbial community structure of activated sludge were studied by adding 100 g·L^-1 TCS to the influent of sequencing batch reactors (SBR) for 185 days. The concentration of nitrate in the reactor with TCS was 3.80-9.11 mg·L^-1, which was slightly lower than that of the control group without TCS (6.66-9.72 mg·L^-1), indicating that the nitrification was weakened. With the extension of domestication time, nitrification recovered gradually. A total of 12 metabolic intermediates were detected by TCS in the process of activated sludge migration and transformation, and four migration and transformation pathways were identified. After the addition of TCS, the relative abundances of bacteria with potential degradation of TCS, such as Flavobacteriales and Myxococcales, were 2.95%-9.07% (0-185 d) and 2.01%-4.53% (0-90 d), respectively. The relative abundances of bacteria related to nitrification, such as Nitrosovibrio, Nitrosomonas (ammonia-oxidizing bacteria, AOB), and Nitrospira (nitrite-oxidizing bacteria, NOB), decreased sharply to 0.80%-0.16% (0-35 d), 0.04%-0.00% (55-90 d), and 0.16%-0.01% (0-35 d), respectively. The relative abundances of denitrifiers, such as Rhodococcus, Stenotrophomonas, and Sphingomonas, did not change significantly. The results of quantitative PCR (qPCR) showed that the abundances of nitrification genes (i.e., amoA, hao, and nxrA) decreased rapidly after adding TCS, from 1.0×10⁶, 2.1×10⁵, and 1.1×10⁶copies·g^-1(on Day 0)to 1.0×10⁵, 8.0×10⁴, and 4.0×10⁵copies·g^-1(on Day 20), respectively. Conversely, the abundance of denitrification genes (i.e., nirK, norB, and nosZ) increased with time, from 5.8×10⁵, 9.8×10⁴, and 3.9×10⁵copies·g^-1 (on Day 0) to 8.2×10⁵, 1.6×10⁵, and 4.1×10⁵copies·g^-1 (on Day 20), respectively, indicating that some TCS-degrading bacteria may also have denitrification abilities. Overall, TCS inhibited the performance of biological nitrification and denitrification, reduced the abundance of nitrogen removal genes, and resulted in differences in microbial community structure, although the effects of TCS gradually weakened over time.