摘要

       本研究评估了质粒编码的抗生素耐药基因（ARGs）在氯水、UV（254nm）和UV/H2O2水处理过程中的灭活效率。采用定量实时PCR（qPCR）方法，对位于pUC4K质粒中的ampR（850bp）和kanR（806bp）扩增子的ARG损伤进行了定量研究。用平板计数法和流式细胞仪分别测定细菌的培养能力和细胞膜损伤等灭活参数。第一部分研究了磷酸盐缓冲液中大肠杆菌失活和ARG损伤的动力学。在所有病例中，ARG损伤的发生比大肠杆菌灭活慢得多。为了在pH 7下实现ARG浓度的4-log降低，所需的氯暴露量和紫外线通量分别为33-72（mg×min）/L和50-130mj/cm~2。当pH值从7增加到8时，氯的ARG损伤率降低，而UV和UV/H2O2的ARG损伤率没有变化。由于细胞成分对氧化剂和紫外线的保护作用，与e-ARGs相比，i-ARGs大多表现出较低的损伤率。在UV/H2O2中，OH自由基对i-ARG损伤的贡献可忽略不计，这是由于细胞组分对OH自由基具有明显的清除作用。在所有情况下，ampR和kanR的ARG损伤率相似，除了e-ARGs的氯化作用，其中ampR的损伤比kanR发生得快。从磷酸盐缓冲溶液中获得的动力学数据和水基质组分预期的氧化剂（氯和OH自由基）需求可以合理解释废水基质中测定的氯和紫外剂量依赖的ARG失活水平。这些结果对优化氯和紫外消毒系统，实现ARGs的灭活具有一定的参考价值。

       This study assessed the inactivation efficiency of plasmid-encoded antibiotic resistance genes (ARGs) both in extracellular form (e-ARG) and present within Escherichia coli (intracellular form, i-ARG) during water treatment with chlorine, UV (254 nm), and UV/H₂O₂. A quantitative real-time PCR (qPCR) method was used to quantify the ARG damage to amp^R (850 bp) and kan^R (806 bp) amplicons, both of which are located in the pUC4K plasmid. The plate count and flow cytometry methods were also used to determine the bacterial inactivation parameters, such as culturability and membrane damage, respectively. In the first part of the study, the kinetics of E. coli inactivation and ARG damage were determined in phosphate buffered solutions. The ARG damage occurred much more slowly than E. coli inactivation in all cases. To achieve 4-log reduction of ARG concentration at pH 7, the required chlorine exposure and UV fluence were 33-72 (mg × min)/L for chlorine and 50-130 mJ/cm² for UV and UV/H₂O₂. After increasing pH from 7 to 8, the rates of ARG damage decreased for chlorine, while they did not vary for UV and UV/H₂O₂. The i-ARGs mostly showed lower rates of damage compared to the e-ARGs due to the protective roles of cellular components against oxidants and UV. The contribution of OH radicals to i-ARG damage was negligible in UV/H₂O₂ due to significant OH radical scavenging by cellular components. In all cases, the ARG damage rates were similar for amp^R versus kan^R, except for the chlorination of e-ARGs, in which the damage to amp^R occurred faster than that to kan^R. Chlorine and UV dose-dependent ARG inactivation levels determined in a wastewater effluent matrix could be reasonably explained by the kinetic data obtained from the phosphate buffered solutions and the expected oxidant (chlorine and OH radicals) demands by water matrix components. These results can be useful in optimizing chlorine and UV-based disinfection systems to achieve ARG inactivation.

       https://www.sciencedirect.com/science/article/abs/pii/S0043135417305328?via%3Dihub