摘要

    最近有报道称，生物活性炭（BAC）过滤是饮用水处理中广泛使用的一种方法，它具有抗生素抗性基因（ARG）。人们对这种新出现的污染了解甚少。使用高通量qPCR和高通量测序进行了这项研究，以研究反洗循环过程中全尺寸BAC过滤器中ARG和细菌群落的发生。在所有生物膜样品中共检测到178个ARG，相对丰度范围为每16S rRNA 0.1至1.37拷贝，绝对丰度范围为4.48×107至3.09×109拷贝/ g碳。从不同滤膜上取样的生物膜共享大多数检测到的ARG和优势属，包括杆菌属（Bryobacter），Pedomicrobium，Reyranella和Terrimonas，尽管它们的细菌群落结构差异很大。反冲洗后，在滤膜成熟期间，所有生物膜样品的相对ARGs丰度提高了1.5倍至3.8倍，绝对ARGs丰度提高了0.90至1.12个对数，表明在此期间ARGs累积在滤膜中。冗余分析表明，此类ARGs的积累主要由冬季的水平基因转移驱动，但与夏季苔藓杆菌和嗜酸杆菌属的相对丰度的增加高度相关。观察到，尽管进行了反冲洗，但仍有80.6％-89.3％的检测到的ARG保留在过滤器中。鉴于BAC过滤器中ARG的丰富度和相对丰度，以及ARG去除中反冲洗的无效性，应采用更严格的下游消毒策略，并且由于饮用水中ARG的持续存在，需要进行更多的研究以评估潜在的人类健康风险。

    Biological activated carbon (BAC) filtration, a process widely used in drinking water treatment, was recently reported to harbor antibiotic resistance genes (ARGs). This emerging contamination is poorly understood. This study was conducted to investigate the occurrence of ARGs and bacterial community in full-scale BAC filters during the backwash cycle using high-throughput qPCR and high-throughput sequencing. A total of 178 ARGs were detected in all biofilm samples, with relative abundance ranging from 0.1 to 1.37 copies per 16S rRNA and absolute abundance ranging from 4.48 × 107 to 3.09 × 109 copies/g carbon. Biofilms sampled from different filters shared most detected ARGs and dominant genera including Bryobacter, Pedomicrobium, Reyranella, and Terrimonas, though their bacterial community structure differed significantly. After backwashing, the relative ARGs abundance increased by 1.5- to 3.8-folds and the absolute ARGs abundance increased by 0.90- to 1.12-logs in all biofilm samples during filter ripening, indicating that ARGs accumulated in filters during this period. Redundancy analysis suggested that such ARGs accumulation was mainly driven by horizontal gene transfer in winter, but highly correlated with the increasing relative abundance of genera Bryobacter and Acidibacter in summer. It was observed that 80.6 %-89.3% of the detected ARGs persisted in the filters despite of the backwashing. Given the high richness and relative abundance of ARGs in BAC filter and the ineffectiveness of backwashing in ARG removal, more stringent downstream disinfection strategies are deserved and more research is necessary to assess potential human health risks due to the persistence of ARGs in drinking water.

    https://www.sciencedirect.com/science/article/abs/pii/S004313542031277X