摘要

       人类活动对环境中抗生素耐药性的传播和持续存在的影响仍远未了解。耐药性的自然背景受人类活动的影响，污水处理厂 (WWTP) 是抗生素耐药性释放到环境中的主要来源之一。污水处理厂的各种处理提供了许多不同的环境条件，可能有利于抗生素抗性基因 (ARG) 的选择，从而有利于它们在环境中的广泛传播。尽管已经深入研究了污水处理厂中不同 ARG 的分布，但对生态学和特定 ARG 选择的分子机制知之甚少。本研究调查了三个污水处理厂中不同 ARG、重金属抗性基因 (HMRG) 和移动元素（I 类整合子）的命运。不同遗传标记的丰度相互关联，它们与影响不同处理阶段微生物群落的生物和非生物因素（总有机碳、总氮、原核细胞丰度及其在单细胞和聚集体中的相对分布）的关系三个污水处理厂，进行了调查。分析了水样中六个 ARG（tetA、sulII、blaTEM、blaCTXM、ermB 和 qnrS）、两个 HMRG（czcA 和 arsB）和 I 类整合子 (int1) 的丰度。测量变量聚集在两个明确定义的组中，第一组包括 tetA、ermB、qnrS 以及不同的生物和非生物因素，第二组围绕基因 sulII、czcA、arsB 和 int1。此外，sulII、HMRGs 和 int1 的动态相关性很强。我们的结果表明 HMRG 在一些 ARG（即 sulII）的传播中发挥着潜在的关键作用，由移动元件介导。污水处理厂中重金属污染与 ARGs 扩散之间可能存在关系，需要进一步研究以阐明共选择机制及其生态，以实现应用处理的去除效率。

       The impact of human activities on the spread and on the persistence of antibiotic resistances in the environment is still far from being understood. The natural background of resistances is influenced by human activities, and the wastewater treatment plants (WWTPs) are among the main sources of the release of antibiotic resistance into the environment. The various treatments of WWTPs provide a number of different environmental conditions potentially favoring the selection of antibiotic resistance genes (ARGs) and thereby their well-documented spread in the environment. Although the distribution of different ARGs in WWTPs has been deeply investigated, very little is known on the ecology and on the molecular mechanisms underlying the selection of specific ARGs. This study investigates the fate of diverse ARGs, heavy metal resistance genes (HMRGs) and of a mobile element (the class I integron) in three WWTPs. Abundances of the different genetic markers were correlated to each other and their relation to biotic and abiotic factors (total organic carbon, total nitrogen, prokaryotic cell abundance and its relative distribution in single cells and aggregates) influencing the microbial communities in the different treatment phases in three WWTPs, were investigated. Water samples were analyzed for the abundance of six ARGs (tetA, sulII, blaTEM, blaCTXM, ermB, and qnrS), two HMRGs (czcA and arsB), and of the class I integron (int1). The measured variables clustered in two well-defined groups, the first including tetA, ermB, qnrS and the different biotic and abiotic factors, and a second group around the genes sulII, czcA, arsB and int1. Moreover, the dynamics of sulII, HMRGs, and int1 correlated strongly. Our results suggest a potentially crucial role of HMRGs in the spread, mediated by mobile elements, of some ARGs, i.e. sulII. The possibility of a relation between heavy metal contamination and the spread of ARGs in WWTPs calls for further research to clarify the mechanisms of co-selection and their ecology, in order to implement the removal efficiency of the applied treatments.

https://www.sciencedirect.com/science/article/pii/S0043135416301087