摘要
      来自医院和其他来源的含有高浓度季铵化合物（QACs）的废水可能会对废水处理厂（WWTP）造成瞬态冲击负荷。反硝化是废水脱氮的关键部分，然而，QACs对反硝化作用的影响以及细胞内和细胞外抗性基因的传播模式仍然未知。本研究系统地研究了三种常见QAC对反硝化作用的短期胁迫。对硝酸盐去除的抑制作用有以下规律：BAC C12＞ATMAC C12＞DADMAC C12。QACs对反硝化性能的抑制作用与Thauera丰度的降低有关，且QACs浓度越高，抑制作用越强。此外，高浓度的QACs可导致活性氧物种的显著减少，抑制细胞活性和细胞外聚合物物质的分泌。此外，在污泥和水中的反硝化系统中，QACs刺激了细胞内和细胞外QACs抗性基因的总体增加。在QACs的冲击负荷下，抗性基因之间发生了共选择，特别是高浓度的BAC C12导致水中抗性基因的丰度显著增加。值得注意的是，污泥和水中的抗性基因主要由不同的细菌贡献。根瘤菌和假单胞菌可能是污泥中抗性基因的潜在宿主，而Thauera主要是水中抗性基因的宿主。
Abstract
The wastewater containing high quaternary ammonium compounds (QACs) concentrations from hospitals and other sources may cause the transient shock loads on the wastewater treatment plants (WWTPs). Denitrification is the key part of nitrogen removal from wastewater, however, the effects of QACs on the denitrification and the spread patterns of intracellular and extracellular resistance genes were still unknown. The short-term stress of three frequently detected QACs on denitrification were systematically investigated in this study. The inhibitory effect on nitrate removal had the following rules: BAC C12 > ATMAC C12 > DADMAC C12. The inhibition of QACs on denitrification performance was correlated with the reduction of Thauera abundance, and a higher QACs concentration made stronger inhibitory effect. Moreover, high concentrations of QACs could cause a significant decrease in reactive oxygen species, inhibit cell activity and extracellular polymeric substances secretion. Furthermore, QACs stimulated an overall increase of intracellular and extracellular QACs resistance genes in denitrification systems, both in sludge and in water. And co-selection among resistance genes occurred under shock loads of QACs, especially a high BAC C12 concentration caused a substantial raise in abundances of resistance genes in water. It was worth noting that resistance genes in sludge and water were mainly contributed by different bacteria. Rhizobium and Pseudomonas may be the potential hosts contributed to resistance genes in sludge while Thauera mainly contributed to that in water.

https://www.sciencedirect.com/science/article/abs/pii/S1385894722046459