Wastewater treatment plants (WWTPs) have been suggested as reservoirs and sources of antibiotic resistance genes (ARGs) in the environment. In a WWTP ecosystem, human enteric and environmental bacteria are mixed and exposed to pharmaceutical residues, potentially favoring genetic exchange and thus ARG transmission. However, the contribution of microbial communities in WWTPs to ARG dissemination remains poorly understood. Here, we examined for the first time plasmid permissiveness of an activated sludge microbial community by utilizing an established fluorescent bioreporter system. The activated sludge microbial community was challenged in standardized filter matings with one of three multidrug resistance plasmids (pKJK5, pB10, and RP4) harbored by Escherichia coli or Pseudomonas putida. Different donor–plasmid combinations had distinct transfer frequencies, ranging from 3 to 50 conjugation events per 100000 cells of the WWTP microbial community. In addition, transfer was observed to a broad phylogenetic range of 13 bacterial phyla with several taxa containing potentially pathogenic species. Preferential transfer to taxa belonging to the predicted evolutionary host range of the plasmids was not observed. Overall, the ARG dissemination potential uncovered in WWTP communities calls for a thorough risk assessment of ARG transmission across the wastewater system, before identification of possible mitigation strategies.

中文翻译：

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估计在污水处理厂微生物群落中编码抗药性的质粒的转移范围

有人建议将废水处理厂（WWTP）用作环境中抗生素抗性基因（ARG）的储存库和来源。在污水处理厂生态系统中，人类的肠道细菌和环境细菌混合在一起并暴露于药物残留物中，从而可能有利于基因交换，进而促进ARG的传播。然而，人们对污水处理厂中微生物群落对ARG传播的贡献知之甚少。在这里，我们通过利用已建立的荧光生物报告系统，第一次检查了活性污泥微生物群落的质粒容许性。活性污泥微生物群落在标准滤器交配中受到大肠杆菌或恶臭假单胞菌（Pseudomonas putida）携带的三种多重耐药质粒（pKJK5，pB10和RP4）之一的挑战。不同的供体-质粒组合具有不同的转移频率，每10万个WWTP微生物群落细胞发生3至50个结合事件。另外，观察到转移到13种细菌门的宽大的系统发育范围，其中几个类群含有潜在的病原体。没有观察到属于质粒的预测进化宿主范围的优先转移至分类单元。总体而言，在污水处理厂社区中发现的ARG传播潜力要求在确定可能的缓解策略之前，对整个废水系统中ARG的传播进行全面的风险评估。