摘要
      河流是抗生素抗性基因（ARGs）的重要载体和宿主。关于ARGs在河流交汇处的传播和健康风险的信息仍然缺乏。在本研究中，宏基因组学用于区分人类活动对汾河、渭河和黄河汇流处ARGs和人类致病菌（HPB）的贡献。杆菌肽抗性基因和bacA在所有河流中最高，分别为1.86×10−2-7.26×10–2和1.79×10−2-9.12×10−2拷贝/16S rRNA拷贝。河流汇流显著增加了ARG的丰度，尤其是在三条河流汇流处，ARG的拷贝数最高为1.53×10−1个/16S rRNA拷贝数。抗生素外排和抗生素靶点改变是三条河流的主要耐药机制。ARGs谱受到多种因素的影响，各种因素的贡献依次为微生物群落>物理化学因素>人类活动>移动遗传元素（MGE）。值得注意的是，人类活动和动物粪便是渭河和黄河ARGs的重要潜在贡献者。Transposons作为三条河流中的主要MGE，在ARGs的转移中发挥了重要作用。三条河流交汇处的MGE丰度最高，具有最大的转移潜力，因此表现出最大的ARGs暴露风险，为232.4拷贝/cap·d。此外，通过共生模式构建了不同河流中ARGs、MGE和HPB的相关性，以系统地说明ARGs的健康风险。本研究首次揭示了河流汇流处ARGs的传播和健康风险，为流域ARGs控制提供了支持。
Abstract
Rivers are important vectors and reservoirs of antibiotics resistance genes (ARGs). Information regarding transmission and health risk of ARGs in river confluence is still lacking. In this study, metagenomics was used to distinguish contributions of human activities on ARGs and human pathogenic bacteria (HPB) in confluence of Fenhe, Weihe, and Yellow Rivers. Bacitracin resistance gene and bacA were the highest in all rivers, with 1.86 × 10−2-7.26 × 10−2 and 1.79 × 10−2-9.12 × 10−2 copies/16S rRNA copies, respectively. River confluence significantly increased the abundance of ARGs, especially at the confluence of three rivers with the highest 1.53 × 10−1 copies/16S rRNA copies. Antibiotic efflux and antibiotic target alteration were the dominant resistant mechanisms in three rivers. ARGs profiles were influenced by multiple factors, with the contributions of various factors ranked as microbial communities > physicochemical factors > human activities > mobile genetic elements (MGEs). Notably, human activities and animal feces were important potential contributors of ARGs in the Weihe River and Yellow River. Transposons, as the main MGEs in three rivers, played important roles in ARGs transfer. The confluence of three rivers had the highest abundance of MGEs with the greatest transfer potentials, and therefore exhibiting the largest exposure risk of ARGs with 232.4 copies/cap·d. Furthermore, correlations of ARGs, MGEs, and HPB in different rivers were constructed via co-occurrence modes to systematically illustrate the health risks of ARGs. This study firstly unveiled the transmission and health risk of ARGs in river confluence, providing supports for ARGs control in watershed.

https://www.sciencedirect.com/science/article/abs/pii/S0048969722070139