污水处理系统中质粒介导的抗生素抗性基因的扩散机制

The rapid dissemination of antibiotic resistance is threatening human health worldwide. Plasmid-mediated horizontal gene transfer is one of the major molecular mechanisms for spread and dissemination of antibiotic resistance to environments. Wastewater treatment plants can act as reservoirs and environmental suppliers of antibiotic resistance. However, knowledges about the mechanisms underlying the spread of antibiotic resistance in wastewater treatment plants are limited, e.g. diversity and abundance of plasmids, antibiotic resistant plasmids with the capacity of horizontal gene transfer as well as their transfer frequencies and potential hosts. In this proposal, samples will be collected from wastewater treatment plants. By applying the high-throughput sequencing for plasmid metagenome, we will characterize the diversity, abundance and distribution of plasmids and antibiotic resistance genes residing on plasmids during wastewater treatment process. By combining filter mating assay with high-throughput sequencing, we will isolate and identify conjugative plasmids with antibiotic resistance and determine their conjugative frequencies. The resistant plasmids with higher transfer frequencies will be then chosen for microcosm experiments and their potential hosts will be identified. Taken together, this project will illustrate the mechanisms for plasmid-mediated dissemination of antibiotic resistance genes in wastewater treatment systems and provide basis for developing management strategies to improve antibiotic resistance mitigation, with the ultimate goal of protecting human health.

抗生素抗性在全球范围内的快速传播与扩散严重威胁了人类健康。质粒介导的抗生素抗性基因（简称抗性基因）的水平基因转移是环境中抗性基因传播与扩散的重要分子机制。污水处理厂是人为来源的抗性基因排放到环境中的重要热区。但是，目前对于污水处理厂中质粒介导的抗性基因水平转移机制尚不清楚，如质粒的多样性和丰度，具有水平转移潜力的抗性质粒库以及它们的转移频率和宿主范围等。本项目将以污水处理厂为研究对象，首先采用质粒宏基因组测序，解析污水处理系统中的质粒及其携带的抗性基因多样性、丰度与分布。进一步采用滤膜接合法筛选和鉴定发生水平转移的抗性质粒并量化其转移频率。针对高频转移的抗性质粒，结合微宇宙培养实验，研究其可能的宿主范围，从而阐明污水处理系统中质粒介导的抗性基因的传播机制。这一研究将为制定相关管理措施遏制抗生素抗性在环境中的蔓延，保护人类健康提供依据。

抗生素抗性在全球范围内的快速传播与扩散严重威胁了人类健康。质粒介导的抗生素抗性基因（简称抗性基因）的水平基因转移是环境中抗性基因传播与扩散的重要分子机制。污水处理厂是人为来源的抗性基因排放到环境中的重要热区。但是，目前对于污水处理厂中质粒介导的抗性基因水平转移机制尚不清楚，如质粒的多样性和丰度，具有水平转移潜力的抗性质粒库以及它们的转移频率和宿主范围等。本项目以污水处理厂为研究对象，首先采用质粒宏基因组测序，解析污水处理系统中的质粒及其携带的抗性基因多样性、丰度与分布。进一步采用滤膜接合法筛选和鉴定发生水平转移的抗性质粒并量化其转移频率。针对高频转移的抗性质粒，结合微宇宙培养实验，研究其可能的宿主范围。本项目研究揭示了污水处理厂及其下游环境微生物污染的多样性和丰度，探明了整合子和噬菌体携带的抗性基因的分布规律，阐明了纳米铁和镉共暴露协同促进质粒介导的抗性质粒水平转移频率。研究成果为阐明抗性基因水平转移过程和传播规律，尽早制定针对性措施，解决日趋严重的细菌耐药问题提供数据。