The Behavior Of Antibiotic Resistome In Activated Carbon Drinking Water Purifiers

The problem of microbial resistance caused by antibiotic abuse is becoming increasingly serious.The drinking water treatment plant is an important part of guaranteeing drinking water quality,but the existing drinking water treatment systems have limited ability to control new pollutants such as antibiotic resistance genes(ARGs).More and more consumers choose to use household water purifiers as an expedient measure to guarantee the drinking water quality.Activated carbon water purifiers are widely used.Scientific evaluation of ARGs behavior in activated carbon water purifiers is of great significance for drinking water safety.In this study,six domestic and foreign brands of household activated carbon drinking water purifiers with different filter structures were purchased.The purification capacities were evaluated,and the dynamic changes of ARGs were tracked by real-time PCR.The comprehensive analysis of antibiotic resistome and bacterial communities in tap water,activated carbon biofilms and filtered water was conducted by metagenomics.Indicator bacteria and key ARGs were screened.“Source Tracker” method was used for traceability analysis to determine the contribution ratio of tap water and activated carbon biofilm to filtered water.The effects of mobile genetic elements(MGEs)on ARGs were explored.It showed that activated carbon drinking water purifiers could effectively remove residual chlorine for a long period of time.The removal effect of organic matter deteriorated with time.The physical properties of activated carbon had a greater impact on water purification performance.Large surface area and high micropore content helped to remove organics.Sintered activated carbon with rigid pores and progressively tight filter structure could play a certain control effect on ARGs.The absolute abundance of ARGs in filtered water reached a high level at 48~80 days in general.A total of 121 subtypes belonging to 13 major types of ARGs were detected in activated carbon drinking water purifiers by metagenomic analysis,and multidrug resistance genes were the most common ARGs.The most influential biomarker in tap water was Mycobacterium,which mainly included Mycobacterium mucogenicum(43% ~ 47%)and Mycobacterium gordonae.Pseudonocardia and Rhodococcus were biomarkers in filtered water and significantly related to several ARGs,which could be used as indicator bacteria for filtered water.Analyses using Source Tracker estimated that the average contribution of activated carbon biofilm to the bacterial community structure of filtered water was 49%,and the average contribution of activated carbon biofilm to the ARGs of filtered water was 34%.The p BBta01,p MKMS02 and p MFLV01 plasmids,and ISMysp3 insertion sequence had significant co-occurrence relationships with ARGs,and played an important role in the proliferation and spread of ARGs in activated carbon biofilms.