摘要

       人类活动在一个地区的迅速扩展会加剧由抗生素耐药基因（ARGs）引起的人类健康风险。城郊生态系统服务于城乡生态系统之间的共生界面，对城郊地区ARGs传播的调查为跟踪ARGs的传播和潜在的缓解措施提供了基本框架。本研究利用高通量定量PCR和16srrna基因高通量测序技术，对城郊河流中ARGs及其宿主菌群的季节分布和地理分布进行了研究。下游ARGs的含量是上游的5.2-33.9倍，表明人类生活区存在明显的耐药性污染。根据附近土地利用分类比较，农田和村庄附近的样品中ARGs的丰度高于背景（3.47-5.58倍），说明近郊地区农业和其他人类活动造成的河流高负荷。利用网络分析揭示的共生模式，提出blaVEB和tetM是ARGs在同一模块中聚集的指标。此外，还观察到ARGs的季节变化和细菌群落的迁移。同时还研究了季节性温度对ARGs沿流域扩散的影响。ARGs绝对丰度最高出现在夏季（平均2.81 × 109 份/L），四季ARG丰度变化趋势与当地气温相似。线性判别分析效应大小（LEfSe）表明，9个细菌属为相应季节的生物标志物。移动遗传因子（MGEs）与ARGs呈显著正相关（P<0.01），MGEs也被认为是导致ARG改变的关键因素。这项研究概述了城市周边河流中ARGs分布的季节和地理变化，并提请注意城市周边生态系统中的污染物控制。

        The rapid expansion of human activity in a region can exacerbate human health risks induced by antibiotic resistance genes (ARGs). Peri-urban ecosystems serve at the symbiotic interface between urban and rural ecosystems, and investigations into the dissemination of ARGs in peri-urban areas provide a basic framework for tracking the spread of ARGs and potential mitigations. In this study, through the use of high-throughput quantitative PCR and 16S rRNA gene high-throughput sequencing, seasonal and geographical distributions of ARGs and their host bacterial communities were characterized in a peri-urban river. The abundance of ARGs in downstream was 5.2-33.9 times higher than upstream, which indicated distinct antibiotic resistance pollution in the areas where human lives. With the comparison classified based on land use nearby, the abundance of ARGs in samples near farmland and villages was higher than in the background (3.47-5.58 times), pointing to the high load in the river caused by farming and other human activities in the peri-urban areas. With the co-occurrence pattern revealed by network analysis, blaVEB and tetM were proposed to be indicators of ARGs which get together in the same module. Furthermore, seasonal variations in ARGs and the transport of bacterial communities were observed. The effects of seasonal temperature on the dissemination of ARGs along the watershed was also evaluated. The highest absolute abundance of ARGs occurred in summer (2.81 × 10⁹ copies/L on average), the trends of ARG abundances in four seasons were similar with local air temperature. The Linear discriminant analysis effect size (LEfSe) suggested that nine bacterial genera were implicated as biomarkers for the corresponding season. Mobile genetic elements (MGEs) showed significant positive correlation with ARGs (P < 0.01) and MGEs were also identified as the key-contributing factor driving ARG alteration. This study provides an overview of seasonal and geographical variations in ARGs distribution in a peri-urban river and draws attention to controlling pollutants in peri-urban ecosystems.

        https://linkinghub.elsevier.com/retrieve/pii/S0160-4120(17)31942-6