摘要

    抗菌素耐药性一直是全球公共卫生关注的焦点。河湖系统是紧密联系的陆地生态系统之一，并且似乎是抗生素抗性基因（ARG）的库和抗性病原体的传播途径，因为它们很容易受到人类活动的影响。目前，在河床系统中，关于ARGs的流行，转移风险和来源的系统知识十分缺乏。在这项研究中，我们专注于在相互联系的河湖系统（中国北部的富河及其接收白洋湖）的沉积物中对ARGs进行高通量分析和源库关系分解。为此，收集了40个表面沉积物用于宏基因组shot弹枪测序。全面表征了ARGs在河湖系统沉积物中的分布和共存特征，以及携带ARGs的移动遗传元件（MGEs）及其潜在的抗虫基因组传播风险。 CrAssphage是一种最近发现的噬菌体，用于追踪人类粪便污染对ARGs的影响。同时，将一种新颖的快速期望最大化微生物源跟踪（FEAST）方法与线性判别分析效果大小方法（LEfSe）相结合，定量分摊了河流沉积物对接收湖中ARGs的贡献。结果表明，在河湖系统的沉积物中检测到丰富多样的ARG（24种类型，由510个亚型组成），包括一些新兴的ARG，例如mcr-1，tetX和碳青霉烯酶类型。网络分析表明，在同一类型和不同类型之间，ARG的非随机共现模式。重要的是，已鉴定出许多携带MGE的重叠群共同含有一个或多个ARG，因此白洋湖的抵抗力风险潜力要高于世界上许多湖泊。来源跟踪表明，河床系统沉积物中ARGs的流行可能在很大程度上由人类粪便污染的程度来解释，并且按分摊估算，从抚河的载运向接收白洋湖贡献了80％以上的ARGs。

    Antimicrobial resistance has been a global public health concern. The river-lake systems are one of the tightly connected terrestrial ecosystems and, appear to be reservoirs of antibiotic resistant genes (ARGs) and dispersal routes of resistant pathogens because they are easily impacted by human activities. Currently, systematic knowledge on the prevalence, transfer risk and source of ARGs in river-lake systems is largely lacking. In this study, we focused on the high-throughput profiling and source-sink relationship disentangling of ARGs in the sediments of an interconnected river-lake system (Fuhe River and its receiving Lake Baiyang in northern China). To this end, 40 surface sediments were collected for metagenomic shotgun sequencing. The profile and co-occurrence of ARGs in the sediments of the river-lake system were comprehensively characterized, as well as the mobile genetic elements (MGEs) carrying ARGs and their potential resistome dissemination risk. CrAssphage, a recently-discovered bacteriophage, was used to track human fecal pollution on the prevalence of ARGs. Meanwhile, a novel fast expectation-maximization microbial source tracking (FEAST) method was combined with linear discriminant analysis effect size method (LEfSe) for quantitatively apportioning the contribution of river sediment to the presence of ARGs in the receiving lake. Results showed abundant and diverse ARGs (24 types consisting of 510 subtypes) were detected in the sediments of the river-lake system, including some emerging ARGs such as mcr-1, tetX and carbapenemases types. Network analysis suggested non-random co-occurrence patterns of ARGs within the same type and among different types. Importantly, a number of MGE-carrying contigs were identified with jointly containing one or more ARGs, resulting in higher resistome risk potential in Lake Baiyang than many worldwide lakes. Source tracking indicated the prevalence of ARGs in the sediments of the river-lake system might be largely explained by the extent of human fecal contamination, and apportionment estimates the load transport from Fuhe River contributed more than 80% of ARGs to the receiving Lake Baiyang.

    https://www.sciencedirect.com/science/article/pii/S0160412019337845