摘要
      废水处理厂是抗生素抗性基因（ARGs）向环境中传播的热点。了解污水处理厂每个处理单元中ARG群落的行为和组装过程可以促进ARG的监测和控制。尽管如此，目前WWTP中的ARG监测缺乏对城市水平和短期日变化的全面评估。因此，在本研究中，通过高通量qPCR对厦门7个污水处理厂的285个ARGs和10个可移动基因元件（MGE）进行了为期7天的监测。结果表明，ARG对污水处理厂的平均日负荷约为1.21×1020拷贝/天，全市共向环境排放1.44×1018拷贝/天。对β-内酰胺、多药、氨基糖苷类和大环内酯林可酰胺链脲菌素B（MLSB）产生耐药性的基因占优势。有趣的是，ARG的丰富度和丰度以及ARG群落组成没有每日差异。随机过程是决定污水处理厂ARG群落聚集的主要力量。每个处理单元中随机过程的相对重要性按进水（INF）>出水（EFF）>活性污泥（AS）的顺序排列。SourceTracker、变异划分分析（VPA）和层次划分分析（HP）的结果表明，来自上游处理单元的细菌和ARG群落分别在AS和EFF中的ARG群落形成中发挥着越来越重要的作用，表明细菌和ARG从源头大规模迁移对废水处理单元中ARG运输的重要性。这强调了我们需要修改减少ARG污染的方法，但要关注城市废水中ARG的来源。
Abstract
Wastewater treatment plants (WWTPs) are the hotspots for the spread of antibiotic resistance genes (ARGs) into the environment. Understanding the behavior and assembly processes of ARG communities in each treatment unit in WWTPs can promote ARG surveillance and control. Despite this, current ARG surveillance in WWTPs lacks comprehensive assessments of the city-level and short-term daily variations. Thus, in this study, 285 ARGs and ten mobile gene elements (MGEs) were monitored in seven WWTPs in Xiamen via high-throughput qPCR for seven days. The results showed that the average daily load of ARG to WWTPs was about 1.21 × 1020 copies/d, and a total of 1.44 × 1018 copies/d was discharged to the environment across the entire city. Genes conferring resistance to beta-lactam, multidrug, aminoglycoside, and macrolide-lincosamide-streptogramin B (MLSB) were dominant. Interestingly, there was no daily difference in the richness and abundance of ARGs as well as ARG community composition. Stochastic processes were the main force determining the assembly of ARG communities in WWTPs. The relative importance of stochastic processes in each treatment unit ranked in the order of influent (INF) > effluent (EFF) > active sludge (AS). The results of SourceTracker, variation partitioning analysis (VPA) and hierarchical partitioning (HP) analysis indicated that bacterial and ARG communities from upstream treatment units played an increasing dominant role in shaping ARG communities in AS and EFF, respectively, suggesting the importance of mass-immigration of bacteria and ARGs from the source on ARG transport in wastewater treatment units. This emphasizes the need to revise the way we mitigate ARG contamination but focus on the source of ARGs in urban wastewater.

https://www.biorxiv.org/content/10.1101/2023.02.27.530348v1.abstract