摘要

    饮用水中经常检测到抗生素抗性基因（ARG），这是一个重大的公共卫生问题。作为典型的饮用水处理过程，由于在过滤过程中建立了过滤器生物膜，因此生物过滤器可能带有各种ARG。这项研究的目的是调查ARGs（blaCTX-M，blaOXA-1，blaTEM，ermB，tetA，tetG，tetQ，tetW，tetX，sul 1，sul 2，dfrA1和dfrA12的行为）及其可能的关联台式生物滤池系统中的细菌。还使用模型结合质粒RP1探索了滤料对水平基因转移（HGT）的影响。生物过滤系统包括四种类型的生物过滤器，包括沙子，颗粒活性炭（GAC），GAC三明治和无烟煤沙生物过滤器。结果表明，尽管ARGs的绝对丰度降低了（平均降低了0.97个对数），但归一化为细菌数量的ARGs的丰度却显示出了滤过水的增加趋势。与深层生物膜相比，从表层收集的生物膜显示出最低的ARG相对丰度（p <0.01），表明在较低位置携带ARG的细菌比例更大。大多数选择的ARG数量与变形杆菌，酸性细菌和硝化螺旋藻相关，分别占生物膜群落的51.9％，5.2％和2.0％。 GAC介质显示出最高的转移频率（2.60×10-5），其次是无烟煤（5.31×10-6）和沙子（2.47×10-6）。反洗可以显着降低RP1质粒在生物膜中的转移能力，但会在浮游生物相中引入更多的共轭结合物。总体而言，这项研究的结果可以增强我们对饮用水生物滤池处理中ARGs患病率的了解。

    Antibiotic resistance genes (ARGs) are being detected in drinking water frequently, constituting a major public health issue. As a typical drinking water treatment process, the biofilter may harbour various ARGs due to the filter biofilms established during the filtration process. The objective of this study was to investigate the behaviour of ARGs (blaCTX-M, blaOXA-1, blaTEM, ermB, tetA, tetG, tetQ, tetW, tetX, sul 1, sul 2, dfrA1 and dfrA12) and their possible association with bacteria in a bench-scale biofiltration system. The impact of filter media on horizontal gene transfer (HGT) was also explored using a model conjugative plasmid, RP1. The biofiltration system comprised four types of biofilters, including sand, granular activated carbon (GAC), GAC sandwich, and anthracite-sand biofilters. Results showed that although the absolute abundance of ARGs decreased (0.97-log reduction on average), the ARGs’ abundance normalised to bacterial numbers showed an increasing trend in the filtered water. Biofilms collected from the surface layer revealed the lowest relative abundance of ARGs (p < 0.01) compared to the deeper layer biofilms, indicating that the proportion of ARG-carrying bacteria was greater in the lower position. Most chosen ARG numbers correlated to Proteobacteria, Acidobacteria and Nitrospirae phyla, which accounted for 51.9%, 5.2% and 2.0% of the biofilm communities, respectively. GAC media revealed the highest transfer frequency (2.60 × 10−5), followed by anthracite (5.31 × 10−6) and sand (2.47 × 10−6). Backwashing can reduce the transferability of RP1 plasmid significantly in biofilms but introduces more transconjugants into the planktonic phase. Overall, the results of this study could enhance our understanding of the prevalence of ARGs in drinking water biofiltration treatment.

    https://www.sciencedirect.com/science/article/abs/pii/S0043135420304917