Influence of chlorinated disinfection by-products on transmission of antibiotic resistance genes in biofilms and water of a simulated drinking water distribution system

Abstract

The spread of antibiotic resistance genes (ARGs) caused by biofilm growth in drinking water distribution systems (DWDSs) poses a serious threat to human health. The influence of disinfection by-products (DBPs) on the distribution of ARGs and mobile genetic elements (MGEs) in different phases (biofilms and water) of DWDSs is unclear. In this study, the characteristics of microbial indices, trihalomethanes (THMs), haloacetic acids (HAAs), ARGs and MGEs in biofilms and effluents of simulated DWDS reactors were detected during 150 d of operation. During the mature biofilm periods of 90 d or 120 d, for both biofilms and effluents, seven categories of ARGs (except tetracycline) and MGEs were at their highest and lowest relative abundance in the entire operation cycle, respectively. The influence of DBPs on ARGs and MGEs in the DWDS was different in different phases. In effluents, DBPs showed a stronger relationship with ARGs compared with MGEs. THMs and HAAs had positive correlations with various ARGs, which indicated that DBPs affected the distribution of resistance genes. In biofilms, the influence of MGEs on ARGs was stronger than that of DBPs on ARGs. Thus, DBPs might be an important contributor to the enrichment and spread of ARGs in water.

Beyond cyanotoxins: increased Legionella, antibiotic resistance genes in western Lake Erie water and disinfection-byproducts in their finished water

“…While this study illustrated that chlorine-related DBPs (THMs and HAA5) were elevated during bloom conditions, yet meeting regulatory thresholds, we suggest to characterize other DBPs that are likely elevated in cyanobacteria-impacted waters. Since there is considerable evidence that THMs and HAAs are linked to ARGs in the finished water and distribution system ( Lv et al, 2014 ; Li and Gu, 2019 ; Zhang et al, 2023 ), we recommend to assess unregulated N-DBPs which likely are less abundant than THMs and HAAs, but are more common in bloom-impacted waters, and able to elicit greater cytotoxicity ( Fang et al, 2010 ; Liu et al, 2020 ) in a future study. In addition, emerging literature indicates that future studies on DBPs ought to consider a broader range of DBPs for also assessing potential human health risks ( Li and Mitch, 2018 ; Kali et al, 2021 ).…”

Ecology and molecular biology of bloom-forming cyanobacteria

“…While this study illustrated that chlorinerelated DBPs (THMs and HAA5) were elevated during bloom conditions, yet meeting regulatory thresholds, we suggest to characterize other DBPs that are likely elevated in cyanobacteriaimpacted waters. Since there is considerable evidence that THMs and HAAs are linked to ARGs in the finished water and distribution system (Lv et al, 2014;Li and Gu, 2019;Zhang et al, 2023), we recommend to assess unregulated N-DBPs which likely are less abundant than THMs and HAAs, but are more common in bloomimpacted waters, and able to elicit greater cytotoxicity (Fang et al, 2010;Liu et al, 2020) in a future study. In addition, emerging literature indicates that future studies on DBPs ought to consider a broader range of DBPs for also assessing potential human health risks (Li and Mitch, 2018;Kali et al, 2021).…”