摘要

        生物膜在整个水生环境中都是普遍存在的，它们被认为能促进抗药性基因（ARGs）的获取和传播。本研究以上海为中心城市，以长江口为研究对象，通过与相关沉积物和水样的对比，研究了自然生物膜中五种ARG的发生和分布。大多数ARGs的检测频率和丰度依次为：生物膜>沉积物>水，这可能是由于高水平的抗生素和金属能促进ARGs在生物膜中的生成和繁殖。生物膜和沉积物样品中的细胞外DNA（eDNA）是ARG丰度的主要来源。eDNA中的ARGs（sul1、sul2、tetA和tetW）与生物膜和沉积物样品中的TOC显著相关。此外，每克微生物生物量碳（MBC）的细胞内DNA相关ARGs和每克非MBC的eDNA相关ARGs均高于沉积物，且eDNA中ARGs在生物膜与水之间的分配系数高于沉积物与水之间的分配系数。研究结果为评价水生环境中ARGs的发生和丰度提供了新的思路，证实生物膜是河口环境中ARGs的重要汇。

          Biofilms are ubiquitous throughout aquatic environments and they are thought to promote the acquisition and dissemination of antibiotic resistant genes (ARGs). This study focused on the occurrence and distribution of five types of ARG in naturally-occurring biofilms, in comparison to associated sediment and water samples, from the Yangtze Estuary, which borders the meta-city of Shanghai, China. The detection frequency and abundances of most ARGs showed the following order: biofilm > sediment > water, which can be attributed to a high level of antibiotics and metals that can accelerate the generation and propagation of ARGs in biofilms. Most of ARG abundances were contributed by extracellular DNA (eDNA) in biofilm and sediment samples. ARGs (sul1, sul2, tetA and tetW) in eDNA were significantly correlated with TOC in both biofilm and sediment samples. Furthermore, both intracellular DNA-associated ARGs per gram of microbial biomass carbon (MBC) and eDNA-associated ARGs per gram of non-MBC and were higher in biofilms than sediments, and the partitioning coefficients of ARGs in eDNA between biofilm and water were higher than those between sediment and water. Our results provide new insight for evaluating the occurrence and abundance of ARGs in aquatic environments, confirming that biofilms are a significant sink for ARGs in the estuarine environment.

        https://linkinghub.elsevier.com/retrieve/pii/S0043-1354(17)30946-6