摘要

       本文研究了游离氯（FAC）、NH2Cl、O3、ClO2和紫外光（254nm）对细胞外和细胞内抗药性基因（eARGs和iARGs）的降解（用qPCR测定）和生物失活（用基于培养的自然转化法测定）以及对eARGs的降解，使用多重耐药枯草芽孢杆菌1A189的染色体ARG（blt）。降解四个266-1017bp扩增子的速率常数，这些扩增子与acfA突变相邻或围绕acfA突变，使blt过度表达，其比例增加至#AT+GC bp s/扩增子，或与#5'-GG-3'或5'-TT-3'双/扩增子成比例，其各自的值在0.59到2.3（×1011 M-1 s-1）之间，用于•OH，O3为1.8-6.9（×104m-1s-1），FAC为3.9-9.2（×103m-1s-1），ClO2为0.35-1.2（×101m-1s-1），pH为7时紫外线为2.0-8.8（×10-2cm2/mJ），pH为8时NH2Cl为1.7-4.4m-1s-1。对于FAC、NH2Cl、O3、ClO2和UV，ARG失活平行降解扩增子，近似于枯草杆菌自然转化所需的800-1000bp acfA侧翼序列，而对于•OH，失活超过降解。在实际的消毒剂暴露条件下，FAC、O3和UV对耳垢和iARGs的降解/失活率均大于90%，但对NH2Cl和ClO2不敏感。iARG的降解/失活总是滞后于细胞的失活。这些发现为评估精氨酸在消毒/氧化过程中的去向提供了一个定量框架，并支持在仔细选择的情况下使用qPCR作为跟踪精氨酸失活的代理。

        This work investigated degradation (measured by qPCR) and biological deactivation (measured by culture-based natural transformation) of extra- and intracellular antibiotic resistance genes (eARGs and iARGs) by free available chlorine (FAC), NH₂Cl, O₃, ClO₂, and UV light (254 nm), and of eARGs by ^•OH, using a chromosomal ARG ( blt) of multidrug-resistant Bacillus subtilis 1A189. Rate constants for degradation of four 266-1017 bp amplicons adjacent to or encompassing the acfA mutation enabling blt overexpression increased in proportion to #AT+GC bps/amplicon, or in proportion to #5'-GG-3' or 5'-TT-3' doublets/amplicon, with respective values ranging from 0.59 to 2.3 (×10¹¹ M^-1 s^-1) for ^•OH, 1.8-6.9 (×10⁴ M^-1 s^-1) for O₃, 3.9-9.2 (×10³ M^-1 s^-1) for FAC, 0.35-1.2(×10¹ M^-1 s^-1) for ClO₂, and 2.0-8.8 (×10^-2 cm²/mJ) for UV at pH 7, and from 1.7-4.4 M^-1 s^-1 for NH₂Cl at pH 8. For FAC, NH₂Cl, O₃, ClO₂, and UV, ARG deactivation paralleled degradation of amplicons approximating a ∼800-1000 bp acfA-flanking sequence required for natural transformation in B. subtilis, whereas deactivation outpaced degradation for ^•OH. At practical disinfectant exposures, eARGs and iARGs were ≥90% degraded/deactivated by FAC, O₃, and UV, but recalcitrant to NH₂Cl and ClO₂. iARG degradation/ deactivation always lagged cell inactivation. These findings provide a quantitative framework for evaluating ARG fate during disinfection/oxidation, and support using qPCR as a proxy for tracking ARG deactivation under carefully selected circumstances.

         https://pubs.acs.org/doi/10.1021/acs.est.8b04393