摘要

已知废水处理厂（WWTP）具有抗生素抗性基因（ARG），其通过流出物传播到环境中。然而，很少有研究比较污水处理厂中ARG的丰度，动员和选择压力，作为二级处理生物过程中变化的函数。我们使用猎枪宏基因组学提供ARG组成的综合分析，与移动遗传元素的关系以及与两个全面的城市污水处理厂的抗生素生产基因（APG）的共同发生，其中一个采用基于生物膜的二级处理，另一个使用暂停的增长系统。结果显示，在两种类型的废水处理过程中，每个基因组当量的ARG的丰度下降超过90％。然而，与移动遗传元件相关的ARG的比例在每个植物的进水和出水之间显着增加，表明在两个处理过程中ARG的显着动员。在悬浮生长系统中的氨基糖苷类抗生素类和生物膜系统中的链霉素抗生素类中发现了ARG和APG之间的强正相关性。生物膜和悬浮生长的污水处理厂在ARG丰度，组成和动员趋势方面表现出相似之处。然而，观察到植物内ARG持久性的明显差异。这些研究结果表明，生物膜和基于悬浮生长的污水处理厂可以促进持久性ARG的遗传动员，然后ARG在流出物中传播到接收水体。

Wastewater treatment plants (WWTPs) are known to harbor antibiotic resistance genes (ARGs) that are disseminated into the environment via effluent. However, few studies have compared abundance, mobilization and selective pressures for ARGs in WWTPs as a function of variations in secondary treatment bioprocesses. We used shotgun metagenomics to provide a comprehensive analysis of ARG composition, relationship to mobile genetic elements and co-occurrences with antibiotic production genes (APGs) throughout two full-scale municipal WWTPs, one of which employs biofilm-based secondary treatment and another that uses a suspended growth system. Results showed that abundances of ARGs declined by over 90% per genome equivalent in both types of wastewater treatment processes. However, the fractions of ARGs associated with mobile genetic elements increased substantially between influent and effluent in each plant, indicating significant mobilization of ARGs throughout both treatment processes. Strong positive correlations between ARGs and APGs were found for the aminoglycoside antibiotic class in the suspended growth system and for the streptogramin antibiotic class in the biofilm system. The biofilm and suspended growth WWTPs exhibited similarities in ARG abundances, composition and mobilization trends. However, clear differences were observed for within-plant ARG persistence. These findings suggest that both biofilm and suspended growth-based WWTPs may promote genetic mobilization of persistent ARGs that are then disseminated in effluent to receiving water bodies.

https://academic.oup.com/femsec/article/94/5/fiy041/4925569