摘要

       抗生素抗性细菌从人为来源传播到环境中，构成了新出现的公共卫生威胁。抗生素抗性基因 (ARG) 和整合子相关整合酶基因 (intI) 等基因捕获系统在微生物群落的改变和抗生素抗性细菌向环境中的传播方面发挥着关键作用。为了评估人为活动对不列颠哥伦比亚省西南部流域的影响，在农业、受城市影响和受保护流域的微生物组中分析了假定的抗生素抗性和整合酶基因的存在。宏基因组学方法和高通量定量 PCR (HT qPCR) 用于筛选包括 ARGs 和 intI 在内的抗性元素。细菌基因组 DNA 的宏基因组测序用于表征 1 年内流域中存在的微生物群落的抗性组。相对于微生物种群，ARG 的流行率较低（<1%）。宏基因组序列分析共检测到 60 个抗性元素，包括 46 个 ARG、intI1 和 groEL/intI1 基因以及所有流域位置的 12 个季铵化合物 (qac) 抗性基因。与城市和受保护的流域相比，受农业影响的流域中 ARG 的相对丰度和丰富度最高。在干旱月份，在受影响的流域（城市和农业）中观察到下游运输模式。与其他报告类似，本研究发现 intI1 和 ARG（例如 sul1）之间存在很强的关联，这种关联可用作人为活动的代理。水样中三大类抗生素的化学分析均低于检测限。然而，受影响地点 ARG 的高丰度和基因拷贝数 (GCN) 表明，即使在水体中的抗菌剂浓度较低的情况下，流出物对微生物群落的影响也会发生。一项为期一年的宏基因组研究中的抗生素抗性和整合酶基因表明，ARGs 主要由来自农业和城市流域中人为化地点的环境因素驱动。土地利用和水质参数等环境因素占流域位置观察到的变异性的 45%。

       The dissemination of antibiotic resistant bacteria from anthropogenic sources into the environment poses an emerging public health threat. Antibiotic resistance genes (ARGs) and gene-capturing systems such as integron-associated integrase genes (intI) play a key role in alterations of microbial communities and the spread of antibiotic resistant bacteria into the environment. In order to assess the effect of anthropogenic activities on watersheds in southwestern British Columbia, the presence of putative antibiotic resistance and integrase genes was analyzed in the microbiome of agricultural, urban influenced, and protected watersheds. A metagenomics approach and high-throughput quantitative PCR (HT qPCR) were used to screen for elements of resistance including ARGs and intI. Metagenomic sequencing of bacterial genomic DNA was used to characterize the resistome of microbial communities present in watersheds over a 1-year period. There was a low prevalence of ARGs relative to the microbial population (<1%). Analysis of the metagenomic sequences detected a total of 60 elements of resistance including 46 ARGs, intI1, and groEL/intI1 genes and 12 quaternary ammonium compounds (qac) resistance genes across all watershed locations. The relative abundance and richness of ARGs was found to be highest in agriculture impacted watersheds compared to urban and protected watersheds. A downstream transport pattern was observed in the impacted watersheds (urban and agricultural) during dry months. Similar to other reports, this study found a strong association between intI1 and ARGs (e.g., sul1), an association which may be used as a proxy for anthropogenic activities. Chemical analysis of water samples for three major groups of antibiotics was below the detection limit. However, the high richness and gene copy numbers (GCNs) of ARGs in impacted sites suggest that the effects of effluents on microbial communities are occurring even at low concentrations of antimicrobials in the water column. Antibiotic resistance and integrase genes in a year-long metagenomic study showed that ARGs were driven mainly by environmental factors from anthropogenized sites in agriculture and urban watersheds. Environmental factors such as land-use and water quality parameters accounted for 45% of the variability observed in watershed locations.

https://www.frontiersin.org/articles/10.3389/fmicb.2018.00852/full