摘要

       湖泊是环境中抗生素耐药基因（ARGs）的自然库之一。在湖泊中长时间的滞留可能会使ARG持续存在，并可能增加出现抗药性病原体的机会。本研究调查了典型城市湖泊太湖（中国）沉积物中ARGs的分布、来源和传播风险，太湖是全球水体富营养化的一个典型例子。利用宏基因组组装技术对太湖沉积物中ARGs的高通量分析进行了表征，并与澳大利亚、加拿大、印度尼西亚、卢旺达和美利坚合众国等全球湖泊中ARGs的高通量分析进行了比较。通过对太湖沉积物中ARG携带菌的分类注释和网络分析，探讨了沉积物中ARGs的寄主，并利用新近发现的crAssphage对耐药菌进行了来源追踪。同时，通过将获得性抗性基因（ARGs）、可移动基因元件（MGEs）和人类细菌病原体的共现投影到三维暴露空间，识别潜在的抗性风险。结果表明，太湖底泥中共检测到321个ARG亚型，隶属于21个ARG亚型，以多药、大环内酯类林可酰胺链霉素、杆菌肽、喹诺酮类、莫匹罗星和甲氧苄啶耐药基因为主。相对而言，太湖沉积物中的ARG含量明显高于其他全球湖泊。污染源追踪显示，太湖沉积物中检测到的碰撞物覆盖率与总ARG覆盖率呈正相关，表明人类粪便污染对该湖ARGs的影响。值得注意的是，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，这可能表明中国第三大淡水湖的抗药性传播风险较高。

       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?via%3Dihub