摘要
      抗生素耐药性基因（ARGs）已成为一个重要的公共卫生问题。特别是，尽管已经在废水处理厂（WWTP）中发现了几种ARG，但很少有研究表明它们对反应器性能的影响。因此，我们的研究试图研究编码多药耐药基因的代表性偶联转移质粒（RP4）对氨氧化的影响。为了实现这一点，我们建立了测序分批反应器（SBRs）和偶联模型，以携带RP4质粒的大肠杆菌供体菌株和典型的氨氧化（AOB）菌株（欧洲硝化单胞菌ATCC 25978）为受体，研究质粒RP4的偶联转移对AOB的影响。我们的研究结果表明，供体菌株携带的RP4质粒可以转移到SBR中的AOB和欧洲硝化单胞菌ATCC 25978。在用携带RP4质粒的供体菌株处理的SBR中，氨去除效率持续下降到71%。一旦RP4质粒进入接合模型中的N.europaea ATCC 25978，氨的去除被显著抑制，亚硝酸盐的产生减少。此外，在转移RP4质粒后，AOB中与氨氧化相关的几个功能基因的表达受到抑制，包括amoA、amoC、hao、nirK和norB。相反，编码细胞色素P460的cytL基因被上调。这些结果表明了污水处理厂中ARGs的生态风险，因此必须采取措施避免其转移。
Abstract
Antibiotic resistance genes (ARGs) have become an important public health concern. Particularly, although several ARGs have been identified in wastewater treatment plants (WWTPs), very few studies have characterized their impacts on reactor performance. Therefore, our study sought to investigate the effect of a representative conjugative transfer plasmid (RP4) encoding multidrug resistance genes on ammonia oxidation. To achieve this, we established sequencing batch reactors (SBRs) and a conjugation model with E. coli donor strains carrying the RP4 plasmid and a typical ammonia-oxidating (AOB) bacterial strain (Nitrosomonas europaea ATCC 25978) as a recipient to investigate the effect of conjugative transfer of plasmid RP4 on AOB. Our findings demonstrated that the RP4 plasmid carried by the donor strains could be transferred to AOB in the SBR and to Nitrosomonas europaea ATCC 25978. In SBR treated with donor strains carrying the RP4 plasmid, ammonia removal efficiency continuously decreased to 71%. Once the RP4 plasmid entered N. europaea ATCC 25978 in the conjugation model, ammonia removal was significantly inhibited and nitrite generation was decreased. Furthermore, the expression of several functional genes related to ammonia oxidation in AOB was suppressed following the transfer of the RP4 plasmid, including amoA, amoC, hao, nirK, and norB. In contrast, the cytL gene encoding cytochrome P460 was upregulated. These results demonstrated the ecological risk of ARGs in WWTPs, and therefore measures must be taken to avoid their transfer.

https://www.sciencedirect.com/science/article/pii/S0043135422003888