摘要

       抗生素抗性基因（ARGs）在城市水生态系统中的发生、传播和组装过程尚不清楚。在这里，我们通过高通量定量 PCR 检测了城市水生态系统中 ARG 的多样性和丰度，包括景观池塘、饮用水水库、中国沿海城市污水处理厂的进水 (IF) 和出水 (EF)。共鉴定出 237 个 ARG，其中多药、氨基糖苷类和 β-内酰胺酶抗性基因最为丰富。城市池塘具有相对较高的多样性和大量与 IF 和 EF 共享的 ARG。池塘中ARGs（1.38×107拷贝/mL）和移动遗传元件（MGEs）（4.19×106拷贝/mL）的平均绝对丰度仅比IFs低一个数量级，但高于EFs和水库。由于 MGE 引起的随机水平基因转移，随机过程主导了 IF 和池塘中的 ARG 群落组装。这些结果意味着城市池塘是 ARG 的热点。我们进一步确定了 25、3 和 11 个指标 ARG，分别用于追踪来自 IF、EF 和池塘的 ARG 污染。我们的研究首次强调了城市池塘在 ARG 传播中的作用。

       The occurrence, dissemination and assembly processes of antibiotic resistance genes (ARGs) in urban water ecosystems are far from being understood. Here, we examined the diversity and abundance of ARGs in urban water ecosystems including landscape ponds, drinking water reservoirs, influents (IFs) and effluents (EFs) of wastewater treatment plants of a coastal city, China through high-throughput quantitative PCR. A total of 237 ARGs were identified, where multidrug, aminoglycoside and beta-lactamase resistance genes were the most abundant. Urban ponds had a comparatively high diversity and large numbers of shared ARGs with IFs and EFs. The average absolute abundance of ARGs (1.38 × 107 copies/mL) and mobile genetic elements (MGEs) (4.19 × 106 copies/mL) in ponds were only one order of magnitude lower than those of IFs, but higher than those of EFs and reservoirs. Stochastic processes dominated the ARG community assembly in IFs and ponds due to the random horizontal gene transfer caused by MGEs. These results imply that urban ponds are hotspots of ARGs. We further identified 25, 3, and 11 indicator ARGs for tracing the ARG contamination from IFs, EFs and ponds, respectively. Our study represents the first to highlight the role of urban ponds in the dissemination of ARGs.

https://www.sciencedirect.com/science/article/abs/pii/S0304389420319981