摘要

       众所周知，污水处理厂 (WWTP) 含有通过污水传播到环境中的抗生素抗性基因 (ARG)。然而，很少有研究将污水处理厂中 ARG 的丰度、动员和选择压力作为二级处理生物过程变化的函数进行比较。我们使用鸟枪宏基因组学对两个全面的市政污水处理厂中的 ARG 组成、与移动遗传元件的关系以及与抗生素生产基因 (APG) 的共存进行了全面分析，其中一个采用基于生物膜的二级处理，另一个使用悬浮生长系统。结果表明，在两种类型的废水处理过程中，每个基因组当量的 ARG 丰度下降了 90% 以上。然而，在每个工厂的进水和出水之间，与移动遗传元件相关的 ARGs 的比例显着增加，表明 ARGs 在两个处理过程中都有显着的动员。对于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球菌素类抗生素，发现 ARG 和 APG 之间存在很强的正相关。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性。然而，观察到植物内 ARG 持久性的明显差异。这些发现表明，生物膜和基于悬浮生长的污水处理厂都可能促进持久性 ARGs 的遗传动员，然后这些 ARGs 在污水中传播到接收水体。

       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?login=true