摘要
      原始河流和城市河流显示出由废水处理厂和生活污水排放等人为影响造成的环境梯度。在这里，宏基因组和装箱分析揭示了抗生素抗性基因（ARGs）的图谱，它们与金属抗性基因（MRGs）和可移动遗传元件（MGE）的共存，以及它们在水中的宿主细菌和河流的白细胞半培养物样本。结果表明，从原始区域到人为区域ARG丰度的降低归因于水微生物群中多药耐药基因的相对丰度沿着环境梯度的降低。而人为影响有助于ARGs在鱼类肠道微生物群中的富集。从原始水样到人为水样，主要宿主细菌从假单胞菌转移到放线菌。从灞河下游的鱼类肠道微生物中检索到具有多种ARGs的潜在病原体副溶血性弧菌、kobei肠杆菌、veronii气单胞菌和铜绿微囊藻_C。携带ARGs（ARC）的重叠群与质粒的比例沿着环境梯度呈上升趋势，这表明质粒在人为压力下起到了有效的流动载体的作用，以增强ARGs的传播。此外，ARGs和MRGs在质粒上的较高共现性表明，人为影响加速了ARGs与MRGs的共转移潜力和ARGs的富集。偏最小二乘路径模型显示，人为污染主要通过影响水中微生物群中的ARG宿主细菌，其次是肠道微生物群中ARG与MGE和MRG共存，从而形成鱼类肠道抗生素耐药性。这项研究增强了我们对人类活动在河流生态系统中传播抗生素耐药性的机制的理解，并强调了ARGs和病原体从水生环境转移到鱼肠的风险。
Abstract
The pristine river and urban river show an environmental gradient caused by anthropogenic impacts such as wastewater treatment plants and domestic wastewater discharges. Here, metagenomic and binning analyses unveiled antibiotic resistance genes (ARGs) profiles, their co-occurrence with metal resistance genes (MRGs) and mobile genetic elements (MGEs), and their host bacteria in water and Hemiculter leucisculus samples of the river. Results showed that the decrease of ARG abundances from pristine to anthropogenic regions was attributed to the reduction of the relative abundance of multidrug resistance genes in water microbiomes along the environmental gradient. Whereas anthropogenic impact contributed to the enrichment of ARGs in fish gut microbiomes. From pristine to anthropogenic water samples, the dominant host bacteria shifted from Pseudomonas to Actinobacteria. Potential pathogens Vibrio parahaemolyticus, Enterobacter kobei, Aeromonas veronii and Microcystis aeruginosa_C with multiple ARGs were retrieved from fish gut microbes in lower reach of Ba River. The increasing trends in the proportion of the contigs carrying ARGs (ARCs) concomitant with plasmids along environmental gradient indicated that plasmids act as efficient mobility vehicles to enhance the spread of ARGs under anthropogenic pressures. Moreover, the higher co-occurrence of ARGs and MRGs on plasmids revealed that anthropogenic impacts accelerated the co-transfer potential of ARGs and MRGs and the enrichment of ARGs. Partial least squares path modeling revealed anthropogenic contamination could shape fish gut antibiotic resistome mainly via affecting ARG host bacteria in water microbiomes, following by ARGs co-occurrence with MGEs and MRGs in gut microbiomes. This study enhanced our understanding of the mechanism of the anthropogenic activities on the transmission of antibiotic resistome in river ecosystem and emphasized the risk of ARGs and pathogens transferring from an aquatic environment to fish guts.

https://www.sciencedirect.com/science/article/abs/pii/S0301479722010945