Microplastics Exacerbated\nConjugative Transfer of\nAntibiotic Resistance Genes during Ultraviolet Disinfection: Highlighting\nDifference between Conventional and Biodegradable Ones

Microplastics (MPs) have been confirmed as a hotspot\nfor antibiotic\nresistance genes (ARGs) in wastewater. However, the impact of MPs\non the transfer of ARGs in wastewater treatment remains unclear. This\nstudy investigated the roles and mechanisms of conventional (polystyrene,\nPS) and biodegradable (polylactic acid, PLA) MPs in the conjugative\ntransfer of ARGs during ultraviolet disinfection. The results showed\nthat MPs significantly facilitated the conjugative transfer of ARGs\ncompared with individual ultraviolet disinfection, and PSMPs exhibited\nhigher facilitation than PLAMPs. The facilitation effects were attributed\nto light shielding and the production of reactive oxygen species (ROS)\nand nanoplastics from ultraviolet irradiation of MPs. The light shielding\nof MPs protected the bacteria and ARGs from ultraviolet inactivation.\nMore importantly, ROS and nanoplastics generated from irradiated MPs\ninduced intracellular oxidative stress on bacteria and further increased\nthe cell membrane permeability and intercellular contact, ultimately\nenhancing the ARG exchange. The greater fragmentation of PSMPs than\nPLAMPs resulted in a higher intracellular oxidative stress and a stronger\nenhancement. This study highlights the concerns of conventional and\nbiodegradable MPs associated with the transfer of ARGs during wastewater\ntreatment, which provides new insights into the combined risks of\nMPs and ARGs in the environment.