Transition of antimicrobial resistome in wastewater treatment plants: impact of process configuration, geographical location and season

Abstract

Antimicrobial resistome in wastewater treatment plants was investigated via shotgun metagenomic analysis over a variety of geographical locations, seasons, and biological treatment configurations. The results revealed that the transition of the antimicrobial resistome occurred at two locations during wastewater treatment, which resulted in a distinctive antimicrobial resistome in influent wastewater, activated sludge, and treated effluent. The antimicrobial resistome in influent wastewater was characterized by a high abundance of antibiotic resistance genes (ARGs) on clinically important drugs, whereas sludge retained a higher abundance of multidrug ARGs associated with efflux pump. Seasonality was the primary factor affecting antimicrobial resistome in influent wastewater, which partially succeeded to the subsequent resistome of activated sludge and treated effluent. Importantly, some ARGs on clinically important drugs in influent wastewater passed through the biological treatment to be discharged in the treated effluent, except in the membrane bioreactor process.

Seasonal Patterns in Mobile Colistin Resistance Gene Variants in Wastewater Bioaerosols and Liquid Sludge

“…Previous studies have examined seasonal differences in WWTP ARG profiles, with varying results showing increases, decreases, or no change in ARG abundance during warmer months compared to cooler months. − These studies found increased ARG abundance during low-rain seasons, fall and winter seasons coinciding with prescription rates, and summer seasons . In this study, while WWTP 1 and 2 are located in different geographic regions with distinct meteorological patterns (Figures S1 and S4), similar seasonal patterns were observed in liquid sludge, with lower ARG and mcr relative abundances occurring during the cooler winter sampling period and increasing throughout the seasons.…”

“…43−45 These studies found increased ARG abundance during low-rain seasons, 43 fall and winter seasons coinciding with prescription rates, 44 and summer seasons. 45 In this study, while WWTP 1 and 2 are located in different geographic regions with distinct meteorological patterns (Figures S1 and S4), similar seasonal patterns were observed in liquid sludge, with lower ARG and mcr relative abundances occurring during the cooler winter sampling period and increasing throughout the seasons. Interestingly, WWTP 3 is in close proximity to WWTP 2 and experiences similar meteorological patterns; however, the liquid sludge at this site showed no seasonal differences in ARG abundance and decreasing mcr abundance from winter to fall seasons.…”

“…While studies have examined factors influencing ARG abundance in WWTP influent, activated sludge, and effluent, − much less is known about the factors influencing ARG abundance in bioaerosols generated during wastewater treatment. Few studies have investigated the impacts of environmental parameters such as temperature and humidity on bioaerosolized ARGs. , In this study, significant spatial and temporal variations in the relative abundances of ARGs and mcr genes were observed in air samples collected from different WWTPs (Figure ; Table S4).…”

ROS-Induced Oxidative Stress Causes Enrichment and Emergence of Antibacterial Resistance in Conventional Activated Sludge Process

“…Moreover, recent studies reported that different WWTP treatment processes could exhibit varying impacts on ARG and ARB dynamics [21][22][23] . Interestingly, the authors identified significant alteration in the ARGs composition in the sludge compared to the of the influent resistome and suggested seasonality in antimicrobial use to be key influencing factor behind this transition 21 .…”

“…Moreover, recent studies reported that different WWTP treatment processes could exhibit varying impacts on ARG and ARB dynamics [21][22][23] . Interestingly, the authors identified significant alteration in the ARGs composition in the sludge compared to the of the influent resistome and suggested seasonality in antimicrobial use to be key influencing factor behind this transition 21 . Another study combining multi-omics approach also revealed that both absolute and relative ARG transcript abundance of the conventional activated sludge (CAS) resistome were significantly enriched with specific ARGs drug classes (multidrug, beta-lactam, aminoglycoside, tetracycline, vancomycin etc.)…”