摘要

       抗生素耐药基因（ARGs）是一类新兴的环境污染物，对公众健康构成威胁。众所周知，在金属污染的土壤中，有毒金属可以作为耐金属细菌的选择，但人们越来越担心，金属污染物也可以作为共选择剂，从而导致环境中抗生素耐药性的扩散。在这项研究中，我们使用高通量qPCR-ARG芯片对贝尔法斯特都市区50个存档城市和郊区土壤中的ARGs和已知的构成潜在ARG宿主的移动遗传元素（MGE）进行了量化。ARG的患病率与单个金属的浓度有关，并根据不同金属对土壤微生物过程的相对毒性计算土壤金属毒性指数。在分析的50种土壤中，共检测到164个ARGs，平均绝对丰度为每克土壤3.4×107个ARGs基因拷贝。ARGs和MGEs的丰度之间存在显著的相关性，表明水平基因转移对ARG的传播具有重要意义。网络分析显示特定金属（砷、镉、钴、铬、铜）之间存在显著的共生模式。汞、镍和锌）以及相关的ARGs。通径分析进一步表明，土壤金属毒性指数通过对MGEs的影响，显著影响了土壤中检测到的ARGs（λ = 0.32，P <0.001）的数量和金属共生ARGs（λ = 0.612，P <0.001）的丰度。总之，我们的结果表明土壤金属在城市和半城市土壤中ARGs和MGEs的共同选择中起作用，并提示通过水平基因转移存在环境ARG传播的风险。

        Antibiotic resistance genes (ARGs) constitute emerging environmental pollutants and pose risks to public health. Toxic metals are known to select for metal-resistant bacteria in metal-contaminated soils, but there is growing concern that metal contaminants can also act as co-selective agents thereby causing environmental proliferation of antibiotic resistance. In this study, we quantified ARGs and selected mobile genetic elements (MGEs) known to constitute potential ARG hosts in 50 archived urban and suburban soils from the Belfast metropolitan area using a high-throughput qPCR ARG chip. ARG prevalence was linked to concentrations of individual metals and a soil metal toxicity index calculated based on the relative toxicity of different metals to soil microbial processes. A total of 164 ARGs were detected across the 50 soils analyzed with an average absolute abundance of 3.4 × 10⁷ ARG gene copies per gram of soil. A significant correlation between abundance of ARGs and MGEs was observed, suggesting the importance of horizontal gene transfer for ARG dissemination. Network analysis revealed significant co-occurrence patterns between specific metals (As, Cd, Co, Cr, Cu. Hg, Ni and Zn) and associated ARGs. Path analysis further indicated that the soil metal toxicity index significantly affected the number of detected ARGs (λ = 0.32, P < 0.001) and the abundance of metal co-occurring ARGs (λ = 0.612, P < 0.001) via effects on MGEs. Collectively, our results indicate a role of soil metals in co-selection of ARGs and MGEs in urban and semi-urban soils and suggest a risk for environmental ARG dissemination via horizontal gene transfer.

        https://www.sciencedirect.com/science/article/pii/S0048969718347284?via%3Dihub