Degradation Kinetics of Antibiotic Resistance Gene mecA of Methicillin-Resistant Staphylococcus aureus (MRSA) during Water Disinfection with Chlorine, Ozone, and Ultraviolet Light
Degradation Kinetics of Antibiotic Resistance Gene mecA of Methicillin-Resistant Staphylococcus aureus (MRSA) during Water Disinfection with Chlorine, Ozone, and Ultraviolet Light
复制标题
DOI：
10.1021/acs.est.0c05274
复制
发表时间：
2021-02-16
影响因子：
11.4
通讯作者：
Lee, Yunho
中科院分区：
文献类型：
--
作者：
Choi, Yegyun;He, Huan;Lee, Yunho
利用耐甲氧西林金黄色葡萄球菌（MRSA）的染色体ARG（mecA），研究了游离有效氯（FAC）、臭氧（O-3）和UV 254光（UV）在pH 7的磷酸盐缓冲溶液中对抗生素耐药基因（ARG）的降解动力学。对于FAC，胞外mecA（extra-mecA）的降解速率随着FAC暴露量的增加而加快，这可以用两步FAC反应模型来解释。O-3对extra-mecA的降解符合二级反应动力学。紫外光降解extra-mecA的拖尾动力学，这可以描述一个新提出的动力学模型，考虑环丁烷嘧啶二聚体（CPD）的形成，其光逆转，和不可逆的（6-4）光产物的形成。测得的速率常数extra-mecA增加与扩增子长度的FAC和O-3，或与数量的链内嘧啶双峰UV，这使得预测的降解速率常数extra-mecA扩增子的序列长度和/或组成的基础上。与extra-mecA相比，在低氧化剂暴露下，FAC和O-3的细胞内mecA（intra-mecA）降解速率更快，但在FAC和UV的高暴露下，降解速率明显较慢。观察到的细胞外和细胞内动力学的差异可能是由于DNA回收效率降低和/或MRSA聚集体的存在而免受消毒剂的影响。
Degradation kinetics of antibiotic resistance genes (ARGs) by free available chlorine (FAC), ozone (O-3), and UV254 light (UV) were investigated in phosphate buffered solutions at pH 7 using a chromosomal ARG (mecA) of methicillin-resistant Staphylococcus aureus (MRSA). For FAC, the degradation rates of extracellular mecA (extra-mecA) were accelerated with increasing FAC exposure, which could be explained by a two-step FAC reaction model. The degradation of extra-mecA by O-3 followed second-order reaction kinetics. The degradation of extra-mecA by UV exhibited tailing kinetics, which could be described by a newly proposed kinetic model considering cyclobutane pyrimidine dimer (CPD) formation, its photoreversal, and irreversible (6-4) photoproduct formation. Measured rate constants for extra-mecA increased linearly with amplicon length for FAC and O-3, or with number of intrastrand pyrimidine doublets for UV, which enabled prediction of degradation rate constants of extra-mecA amplicons based on sequence length and/or composition. In comparison to those of extra-mecA, the observed degradation rates of intracellular mecA (intra-mecA) were faster for FAC and O-3 at low oxidant exposures but significantly slower at high exposures for FAC and UV. Differences in observed extra- and intracellular kinetics could be due to decreased DNA recovery efficiency and/or the presence of MRSA aggregates protected from disinfectants.