摘要

       湖泊是环境中抗生素抗性基因 (ARG) 的天然储存库之一。在湖泊中较长的保留时间可能会使 ARG 持续存在，并可能为出现抗性病原体的机会增加。在这项研究中，我们调查了典型城市湖泊太湖（中国）沉积物中 ARGs 的流行、来源和传播风险，太湖因其大量蓝藻水华而成为世界上富营养化水污染的一个严重例子。太湖沉积物中ARGs的高通量分析以宏基因组组装为特征，并与来自澳大利亚、加拿大、印度尼西亚、卢旺达和美国的其他全球湖泊进行了比较。基于携带ARG的contigs的分类注释和网络分析，探索了太湖沉积物中ARGs的宿主，并利用新发现的crAssphage对耐药菌进行溯源。同时，通过将获得性 ARG、移动遗传元件 (MGE) 和人类细菌病原体的共存投射到三维暴露空间中，确定了潜在的耐药风险。结果表明，在太湖沉积物中检测到321个ARG亚型，属于21个ARG类型，以多药、大环内酯-林可酰胺-链霉菌素、杆菌肽、喹诺酮、莫匹罗星和甲氧苄啶耐药基因为主。相对而言，太湖沉积物中ARG水平明显高于全球其他湖泊。源头追踪显示太湖沉积物中检测到的crAssphage的覆盖率与总ARG覆盖率呈正相关，表明人类粪便污染对该湖中ARGs的流行有贡献。需要指出的是，太湖沉积物中ARGs、MGEs和人类病原体的共生率高于全球其他湖泊，可能表明中国第三大淡水湖中耐药性传播的风险更高。

       Lakes are one of the natural reservoirs of antibiotic resistance genes (ARGs) in environments. Long retention times in lakes potentially allow ARGs to persist and may create increased opportunities for the emergence of resistant pathogens. In this study, we investigated the prevalence, source and dissemination risk of ARGs in the sediments of a typical urban lake, Lake Tai (China) which has been a drastic example of water pollution with eutrophication in the world due to its proliferated cyanobacterial blooms. High-throughput profilings of ARGs in the sediments of Lake Tai were characterized with metagenomic assembly, and were compared with those in other global lakes from Australia, Canada, Indonesia, Rwanda and the United States of America. The hosts of ARGs in the sediments of Lake Tai were explored based on the taxonomic annotation of ARG-carrying contigs and network analysis, and a novel recently-discovered crAssphage was employed for source tracking of resistance bacteria. Meanwhile, the potential resistome risk was identified by projecting the co-occurrence of acquired ARGs, mobile genetic elements (MGEs) and human bacterial pathogens into a three-dimensional exposure space. Results showed 321 ARG subtypes belonging to 21 ARG types were detected in the sediments of Lake Tai, dominated by multidrug, macrolide-lincosamide-streptogramin, bacitracin, quinolone, mupirocin and trimethoprim resistance genes. Relatively, the ARG levels in the sediments of Lake Tai were significantly higher than those in other global lakes. Source tracking showed the coverages of detected crAssphage in the sediments of Lake Tai were positively correlated with the total ARG coverage, suggesting the contribution of human fecal contamination to the prevalence of ARGs in this lake. It should be noted that the co-occurrence ratio of ARGs, MGEs and human pathogens in the sediments of Lake Tai was higher than that in other global lakes, likely indicating a higher risk for the resistance dissemination in the China's third largest freshwater lake.

https://www.sciencedirect.com/science/article/pii/S016041201930501X