摘要
There is a need to improve understanding of the effect of chlorine disinfection on antibiotic resistance genes (ARGs) in order to advance relevant drinking water, wastewater, and reuse treatments. However, few studies have explicitly assessed the physical effects on the DNA. Here we examined the effects of free chlorine (1-20 mg CI2/L) on extracellular genomic, plasmid DNA and select ARGs. Chlorination was found to decrease the fluorometric signal of extracellular genomic and plasmid DNA (ranging from 0.005 to 0.05 μg/mL) by 70%, relative to a no-chlorine control. Resulting DNA was further subject to a fragment analysis using a Bioanalyzer, indicating that chlorination resulted in fragmentation. Moreover, chlorine also effectively deactivated both chromosomal- and plasmidborne ARGs, mecK and tetA., respectively. For concentrations >2 mg CI2//L× 30 min, chlorine efficiently reduced the qPCR signal when the initial concentration of ARGs was 10^5 copies/μL or less. Notably, genomic DNA and mecA gene signals were more readily reduced by chlorine than the plasmid-bome tetK gene (by ~2 fold). Based on the results of qPCR with short (~200 bps) and long amplicons (-1200 bps), chlorination could destroy the integrity of ARGs, which likely reduces the possibility of natural transformation. Overall, our findings strongly illustrate that chlorination could be an effective method for inactivating extracellular chromosomal- and plasmid-bome DNA and ARGs.
基金
the National Science Foundation Partnership in International Research and Education (PIRE): OISE Award # 1545756,“Halting Environmental Antimicrobial Resistance Dissemination”
National Key Research and Development Program of China-International collaborative project from Ministry of Science and Technology (No. 2017YFE0107300)
Virginia Tech ICTAS Center for Science and Engineering of the Exposome (SEE)
The Virginia Tech National Center for Earth and Environmental Nanotechnology National Science Foundation Grant (NNCI-1542100).