摘要

    环境中的抗生素抗性基因（ARG）对人类和动物具有暴露风险，并且正在成为全球公共卫生关注的焦点。在这项研究中，在受控条件下，在两种pH值不同的澳大利亚非农业土壤中，研究了汞（Hg）驱动的ARG的共选择。在土壤中掺入增加浓度的无机汞，并放置5年。两种土壤都含有赋予四环素（tetA，tetB），磺酰胺（sul1），甲氧苄啶（dfrA1）和ARG指示剂1类整合素整合酶基因intI1抗性的ARG，通过qPCR测定。没有检测到最后的抗生素万古霉素抗性基因vanB和喹诺酮抗性基因qnrS。在测试的汞浓度范围内，在碱性土壤中观察到了汞驱动的几种ARG的共选择，即intI1，tetA和tetB。在中性pH值土壤中未观察到实验性ARG的共选。 16S rRNA测序揭示了分别在汞污染的中性和碱性土壤中变形杆菌和细菌的增殖。多变量分析显示，汞，土壤pH值和有机碳含量对实验土壤中ARGs的共选具有强烈影响。另外，尽管衰老导致汞含量显着降低，但是农业上重要的细菌门如硝化螺旋藻并没有在受污染的土壤中重新生长。结果表明，汞可以驱动受污染的非农业土壤经过5年的老化而共同选择ARG，这与土壤微生物群的移动和土壤中的金属化学有关。

    Antibiotic resistance genes (ARGs) in the environment are an exposure risk to humans and animals and is emerging as a global public health concern. In this study, mercury (Hg) driven co-selection of ARGs was investigated under controlled conditions in two Australian non-agricultural soils with differing pH. Soils were spiked with increasing concentrations of inorganic Hg and left to age for 5 years. Both soils contained ARGs conferring resistance to tetracycline (tetA, tetB), sulphonamides (sul1), trimethoprim (dfrA1) and the ARG indicator class 1 integron-integrase gene, intI1, as measured by qPCR. The last resort antibiotic vancomycin resistance gene, vanB and quinolone resistance gene, qnrS were not detected. Hg driven co-selection of several ARGs namely intI1, tetA and tetB were observed in the alkaline soil within the tested Hg concentrations. No co-selection of the experimental ARGs was observed in the neutral pH soil. 16S rRNA sequencing revealed proliferation of Proteobacteria and Bacteriodetes in Hg contaminated neutral and alkaline soils respectively. Multivariate analyses revealed a strong effect of Hg, soil pH and organic carbon content on the co-selection of ARGs in the experimental soils. Additionally, although aging caused a significant reduction in Hg content, agriculturally important bacterial phyla such as Nitrospirae did not regrow in the contaminated soils. The results suggest that mercury can drive co-selection of ARGs in contaminated non-agricultural soils over five years of aging which is linked to soil microbiota shift and metal chemistry in the soil.

    https://www.sciencedirect.com/science/article/abs/pii/S0269749120305133