Microbial Ecology Group, National Research Council - Institute of Ecosystem Study (CNR-ISE), Largo Tonolli 50, 28922, Verbania, Italy.
Proteomics and Microbiology Lab, Mons University, 5 av du Champ de Mars, B-7000, Mons, Belgium.
Water Res. 2016 May 1;94:208-214. doi: 10.1016/j.watres.2016.02.049. Epub 2016 Feb 23.
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.
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被理解。耐药性的自然背景受到人类活动的影响，而废水处理厂 (WWTP) 是抗生素耐药性向环境释放的主要来源之一。WWTP 的各种处理方法提供了许多不同的环境条件，可能有利于选择抗生素耐药基因 (ARGs)，从而记录了它们在环境中的广泛传播。尽管已经深入研究了 WWTP 中不同 ARGs 的分布情况，但对于特定 ARGs 选择的生态学和分子机制却知之甚少。本研究调查了三种 WWTP 中多种 ARGs、重金属耐药基因 (HMRGs) 和一个移动元件（I 类整合子）的命运。不同遗传标记的丰度相互关联，并调查了它们与影响三个 WWTP 中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）之间的关系。对水样中的六种 ARGs（tetA、sulII、blaTEM、blaCTX-M、ermB 和 qnrS）、两种 HMRGs（czcA 和 arsB）和 I 类整合子（int1）的丰度进行了分析。所测变量聚类为两个定义明确的组，第一组包括 tetA、ermB、qnrS 和不同的生物和非生物因素，第二组包括 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，重金属污染与 WWTP 中 ARGs 传播之间存在潜在的关键联系，这种传播是由移动元件介导的，例如 sulII。需要进一步的研究来阐明共选择的机制及其生态学，以便提高应用处理方法的去除效率，以澄清重金属污染与 WWTP 中 ARGs 传播之间的关系。
