摘要

已知废水处理厂（WWTP）具有通过流出物传播到环境中的抗生素抗性基因（ARG）。然而，很少有研究将废水处理厂的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技术对ARG组成，与移动遗传元件的关系以及与两个全面市政污水处理厂中抗生素生产基因（APG）的共生现象进行综合分析，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，ARGs的丰度均降低了90％以上。然而，与移动遗传因子（MGEs）相关的ARGs部分在每个植物的进水和出水之间大幅增加，这表明ARG在整个两个处理过程中都有显着的动员。在悬浮生长系统中氨基糖苷类抗生素类和生物膜系统中链霉抗生素类发现了ARG和APG之间强烈的正相关性。生物膜和悬浮生长污水处理厂在ARG丰度，成分和动员趋势方面表现出相似之处。然而，对于植物内ARG持久性观察到明显的差异。这些发现表明生物膜和基于悬浮生长的废水处理厂都可以促进遗传动员持续性ARGs，然后将这些ARGs在污水中传播到接受水体中。

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 antibioticproduction 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 (MGEs) 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 wastewater treatment plants may promote genetic mobilization of persistent ARGs that are then disseminated in effluent to receiving water bodies.

https://www.ncbi.nlm.nih.gov/pubmed/29534199