Metagenomics analysis of antibiotic resistance genes, the bacterial community and virulence factor genes of fouled filters and effluents from household water purifiers in drinking water.

The aim of this study was to explore the influence and removal of household water purifiers (HWPs) on emerging contaminants in drinking water, and their distribution characteristics. The antibiotic resistance genes (ARGs), mobile genetic elements (MGEs), virulence factor genes (VFGs) and bacterial communities were profiled in the fouled filters, influents, and effluents from HWPs with five steps of filtration after 150 days operation, using metagenomics. The results showed that the diversity of dominant species in Poly Propylene 1 μm (PP1) and nanofiltration membrane (NM) was significantly higher than that in other filters. Post-activated carbon (AC) was used to detect low species richness or diversity, and the highest proportion of dominant species, which contributes to the greater microbial risk of HWPs effluents in drinking water. The number of dominant bacterial genera in the filters disinfected with chloramine was higher than that in the same group disinfected with chlorine. The bacterial species richness or diversity in water was reduced by the purification of HWPs because the filter elements effectively trapped a variety of microorganisms. The relative abundance of Antibiotic efflux in the effluents of chlorinated and chloraminated HWPs was 5.58 × 10-3 and 4.60 × 10-3, respectively, which was the main resistance mechanism. High abundance of VFGs was found in HWPs effluents and the relative abundance of aggressive VFGs was significantly higher than those of defensive VFGs. Based on the co-occurrence results, 243 subtypes of ARGs co-occurred with VFGs, and a variety of bacteria were thought to be possible ARGs hosts, which indicated that the host bacteria of VFGs in HWP effluents had a stronger attack ability. The effluent of HWPs with only filtration processes is exposed to the risk of ARGs and VFGs. This study helps to understand the actual purification effect of HWPs and provides a theoretical reference for the management and control of ARGs pollution in domestic drinking water.