摘要

       众所周知，废水处理厂（WWTPs）含有抗生素抗性基因（ARG），这些基因通过废水传播到环境中。然而，很少有研究将污水处理厂中精氨酸的丰度、动员和选择性压力作为二级处理生物过程变化的函数进行比较。我们利用鸟枪基因组学对两个完整的城市污水处理厂的精氨酸组成、与移动遗传元素的关系以及与抗生素生产基因（APG）的共现进行了全面分析，其中一个污水处理厂采用基于生物膜的二次处理，另一个污水处理厂采用悬浮生长系统。结果表明，在两种污水处理工艺中，ARGs的丰度每基因组减少90%以上。然而，与流动基因元件相关的精氨酸组分在每种植物的进水和出水之间显著增加，表明精氨酸在两种处理过程中都有显著的迁移。悬浮生长系统中氨基糖苷类抗生素和生物膜系统中链霉素类抗生素的ARGs与APGs呈极显著正相关。生物膜和悬浮生长污水处理厂的ARG丰度、组成和迁移趋势相似。然而，在植物内ARG的持久性方面观察到了明显的差异。这些发现表明，生物膜和悬浮生长型污水处理厂都可能促进持久性精氨酸的遗传动员，这些精氨酸随后在污水中传播到受纳水体。

        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