摘要
      地下水是一项重要的公共和饮用水供应，其保护是全球政策的一个目标。在这里，我们调查了城市地区不同距离的地下水环境中抗生素残留，抗生素抗性基因（ARG），移动遗传因子（MGE）和微生物污染的存在和流行情况。抗生素浓度范围从低于检测限度到917ng / L，是甲氧苄啶，大环内酯类和磺胺类抗生素类最丰富的类别。通过qPCR检测，共检测到11种ARGs（氨基糖苷类，β-内酰胺类，氯霉素，大环内酯类，林可酰胺类，Streptogramin B-MLSB，磺胺类，四环素类），一种防腐剂基因和两种MGEs，相对丰度范围为6.61×10- 7至2.30×10-1拷贝/ 16S rRNA基因拷贝。 ARG和MGE在调查的地下水环境中广泛存在，不仅在城市而且在偏远地区的丰度也有所增加。观察到不同的细菌群落特征，受影响较小区域的Betaproteobacteria和Bacteroidetes以及受污染的地下水中的Firmicutes的流行率较高。物种多样性增加，系统发育成分不同以及粪便和/或致病菌可能存在的综合特征可能表明不同类型的污染。确定了地下水细菌群落内ARG，MGEs和特定分类群之间的显着相关性，揭示了潜在的抗性类型宿主。虽然没有通用标记基因可以确定，但是确定了具有tetC，tetO，tetW抗性基因的int1，qacEΔ1和sulI基因（人为污染的替代组）的共同选择。由于tet组被观察到遵循本研究中调查的地下水样本的环境污染模式，我们的结果强烈支持这组基因作为人类影响的环境示踪剂的建议。总体而言，本研究调查了地下水生境中几种新出现的污染物，这些污染物可能包含在监测计划中，以实现进一步的监管和保护措施。

Groundwater is an essential public and drinking water supply and its protection is a goal for global policies. Here, we investigated the presence and prevalence of antibiotic residues, antibiotic resistance genes (ARGs), mobile genetic elements (MGEs), and microbial contamination in groundwater environments at various distances from urban areas. Antibiotic concentrations ranged from below detection limit to 917 ng/L, being trimethoprim, macrolide, and sulfonamide the most abundant antibiotic classes. A total of eleven ARGs (aminoglycoside, β-lactam, chloramphenicol, Macrolide-Lincosamide-Streptogramin B - MLSB, sulfonamide, and tetracycline), one antiseptic resistance gene, and two MGEs were detected by qPCR with relative abundances ranging from 6.61 × 10−7 to 2.30 × 10−1copies/16S rRNA gene copies. ARGs and MGEs were widespread in the investigated groundwater environments, with increased abundances not only in urban, but also in remote areas. Distinct bacterial community profiles were observed, with a higher prevalence of Betaproteobacteria and Bacteroidetes in the less-impacted areas, and that of Firmicutes in the contaminated groundwater. The combined characteristics of increased species diversity, distinct phylogenetic composition, and the possible presence of fecal and/or pathogenic bacteria could indicate different types of contamination. Significant correlations between ARGs, MGEs and specific taxa within the groundwater bacterial community were identified, revealing the potential hosts of resistance types. Although no universal marker gene could be determined, a co-selection of int1, qacEΔ1 and sulI genes, a proxy group for anthropogenic pollution, with the tetC, tetO, tetW resistance genes was identified. As the tetgroup was observed to follow the pattern of environmental contamination for the groundwater samples investigated in this study, our results strongly support the proposal of this group of genes as an environmental tracer of human impact. Overall, the present study investigated several emerging contaminants in groundwater habitats that may be included in monitoring programs to enable further regulatory and protection measures.

https://www.sciencedirect.com/science/article/pii/S0269749117343543