摘要
      由于大坝的广泛建设，河流水库系统在现代全球水环境中变得无处不在。然而，人们对抗生素耐药性基因（ARG）在经历不同程度的人为影响的水库河流系统中的分布知之甚少。本文利用高通量定量PCR技术，对中国东南部典型的亚热带水库-河流系统岷江干流ARGs的多样性、丰度和空间分布进行了综合表征。从12个采样点共检测到252种ARG亚型，这些采样点以aac（3）-Via为主，其次是czcA、blaTEM和sul1。城市河水（站点S9–S12）比水库水（站点S1–S7）含有更多样化的ARG，这表明在人口密度较大的地区，抗生素耐药性污染更严重。大坝建设可能会降低从上游（站点S7）到下游（站点S8）ARG的丰富度和绝对丰度。城市河水中也含有更高比例的流动遗传元素（MGE），这表明密集的人类活动可能促进ARG水平基因转移。能够促进微生物群落中抗生素耐药性的变形杆菌的平均相对丰度在城市河水中也最高。方差划分分析表明，MGE和细菌群落可以分别解释整个流域、水产养殖水域和城市河水中选定ARGs的67.33%、44.7%和90.29%的变化。这些结果进一步表明，城市河流是获取和传播ARGs的理想介质。这些发现为确定水库-河流系统中ARGs分布的发生和潜在机制提供了新的见解，该系统在流域尺度上经历了各种人为干扰。
Abstract
River-reservoir systems have become ubiquitous among modern global aquatic environments due to the widespread construction of dams. However, little is known of antibiotic resistance gene (ARG) distributions in reservoir-river systems experiencing varying degrees of anthropogenic impacts. Here, the diversity, abundance, and spatial distribution of ARGs were comprehensively characterized along the main stem of the Minjiang River, a typical subtropic reservoir-river system in Southeast China using high-throughput quantitative PCR. A total of 252 ARG subtypes were detected from twelve sampling sites that were dominated by aac(3)-Via, followed by czcA, blaTEM, and sul1. Urban river waters (sites S9–S12) harbored more diverse ARGs than did the reservoir waters (sites S1–S7), indicating more serious antibiotic resistance pollution in areas with larger population densities. Dam construction could reduce the richness and absolute abundance of ARGs from upstream (site S7) to downstream (site S8). Urban river waters also harbored a higher proportion of mobile genetic elements (MGEs), suggesting that intensive human activities may promote ARG horizontal gene transfers. The mean relative abundance of Proteobacteria that could promote antibiotic resistance within microbial communities was also highest in urban river waters. Variance partitioning analysis indicated that MGEs and bacterial communities could explain 67.33%, 44.7%, and 90.29% of variation in selected ARGs for the entire watershed, aquaculture waters, and urban river waters, respectively. These results further suggest that urban rivers are ideal media for the acquisition and spread of ARGs. These findings provide new insights into the occurrence and potential mechanisms determining the distributions of ARGs in a reservoir-river system experiencing various anthropogenic disturbances at the watershed scale.

https://www.sciencedirect.com/science/article/abs/pii/S0301479722017273