摘要

这项工作通过游离有效氯（FAC），NH2Cl，O3，ClO2和UV研究了细胞外和细胞内抗生素抗性基因（eARGs和iARGs）的降解（通过qPCR测量）和生物失活（通过基于培养的自然转化测量）。使用多药耐药性枯草芽孢杆菌1A189的染色体ARG（blt），通过•OH，轻（254nm）和eARG。与#fcA突变相邻或包含acfA突变的四个266-1017bp扩增子的降解速率常数使得blt过表达与#AT + GC bps /扩增子成比例增加，或与＃5'-GG-3'或5'-TT成比例增加-3'双峰/扩增子，相应的值范围为0.59至2.3（×1011 M-1 s-1）•OH，1.8-6.9（×104 M-1 s-1）O3,3.9-9.2（× FAC为103 M-1 s-1），ClO 2为0.35-1.2（×101 M-1 s-1），pH为7时为2.0-8.8（×10 -2 cm 2 / mJ），1.7- 4.4在pH8下对于NH2Cl的M-1s-1。对于FAC，NH2Cl，O3，ClO2和UV，ARG失活平行于扩增子的降解，接近于枯草芽孢杆菌自然转化所需的~800-1000bp acfA-侧翼序列。 ，而去激活超过了•OH的退化。在实际的消毒剂暴露中，eARG和iARGs被FAC，O3和UV降解/失活≥90％，但对NH2Cl和ClO2不敏感。 iARG降解/失活总是滞后细胞失活。这些发现为评估消毒/氧化期间的ARG命运提供了定量框架，并支持使用qPCR作为在精心选择的情况下跟踪ARG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/abs/10.1021/acs.est.8b04393