摘要

        污水处理厂（WWTPs）中的细胞相关ARGs一直备受关注，但对其无细胞ARGs的研究却很少。本研究以大型城市污水处理厂为研究对象，研究了四种具有代表性的ARGs，sulII，tetC，blaPSE-1和ermB在细胞相关组分和无细胞组分中的丰度。细胞相关ARGs是原水中主要的ARGs组分。经过生物处理、污泥沉降、膜过滤和消毒后，细胞相关的ARGs显著减少，但ARG/16srrna基因的比例随着消毒的进行而增加。无单元ARGs在污水处理厂中持续存在，从0.36个日志删除到2.68个日志，这远远低于删除与单元相关的ARGs（从3.21个日志删除到4.14个日志）。因此，在处理过程中，无细胞ARGs与细胞相关ARGs的丰度比从0.04-1.59%增加到2.00-1895.08%。经过25天的贮存，生物出水和消毒出水中的无细胞ARGs分别增加了0.14log 1.99log 0.12log1.77log0，反映了出水中无细胞ARGs的持久性和低衰减率。因此，无细胞ARGs可能是污水处理厂一种重要但被忽视的污染物，给污水接收环境增加了潜在的风险。

        Cell-associated ARGs in wastewater treatment plants (WWTPs) has been concerned, however, cell-free ARGs in WWTPs was rarely studied. In this study, the abundances of four representative ARGs, sulII, tetC, bla_PSE-1, and ermB, in a large municipal WWTP were investigated in both cell-associated and cell-free fractions. Cell-associated ARGs was the dominant ARGs fraction in the raw wastewater. After biological treatment, sludge settling, membrane filtration, and disinfection, cell-associated ARGs were substantially reduced, though the ratios of ARG/16S rRNA gene were increased with disinfection. Cell-free ARGs persisted in the WWTP with a removal of 0.36 log to 2.68 logs, which was much lower than the removal of cell-associated ARGs (3.21 logs to 4.14 logs). Therefore, the abundance ratio of cell-free ARGs to cell-associated ARGs increased from 0.04-1.59% to 2.00-1895.08% along the treatment processes. After 25-day-storage, cell-free ARGs in both biological effluent and disinfection effluent increased by 0.14 log to 1.99 logs and 0.12 log to 1.77 logs respectively, reflecting the persistence and low decay rate of cell-free ARGs in the discharge water. Therefore, cell-free ARGs might be a kind of important but previously neglected pollutant from WWTPs, which added potential risks to the effluent receiving environments.

        https://pubs.acs.org/doi/10.1021/acs.est.7b04283