Micro- and nanoplastics facilitate the propagation of antimicrobial resistance in mixed microbial consortia

Navigating the emerging pollutant crisis appears increasingly daunting, with the interaction between micro- and nanoplastics (M/NPs) and antimicrobial resistance (AMR) in complex microbial consortia remaining poorly understood. Here, mixed-culture microcosms are subjected to polymer- and size-resolved plastic exposures, and resistome and mobilome dynamics are quantified using phenotyping and multi-omics. M/NP exposure increases AMR gene abundance and reshapes resistance profiles in a polymer-dependent manner, dominated by efflux and target alteration. Particle miniaturization amplifies resistome diversity and gene mobility, and nanoplastics show the highest horizontal gene transfer activity and strongest co-localization of AMR genes with mobile genetic elements, forming dense cross-phylum transfer networks. Mechanistically, nanoplastics elevate ROS and membrane damage, activate the SOS response, and upregulate conjugation, competence, and transposase functions. Increased ATP generation and efflux activity sustain stress tolerance and energy-intensive DNA exchange, turning nanoplastics into hotspots of transferable resistance with implications for microbial evolution and ecological resilience.