Activated sludge plays a central role in reducing potentially pathogenic bacteria and high-risk antimicrobial resistance genes by investigating intra- and extracellular DNA

Wastewater treatment plants are widely recognized as hotspots for antimicrobial resistance. Although activated sludge processes are not designed to lower the abundance of pathogens or antimicrobial resistance genes (ARGs), their effects on the pathobiome and antimicrobial resistome require in-depth investigation. We collected wastewater samples before and after activated sludge process from five municipal wastewater treatment plants and extracted both intracellular and extracellular DNA. Shotgun sequencing was performed to characterize the bacterial community, pathobiome, and antimicrobial resistome. Our results showed that activated sludge processes significantly reduced the abundance of both potentially pathogenic bacteria and high-risk ARGs. However, viral particles carrying ARGs resulted enriched, highlighting a potential risk for ARG spreading during these processes.