Chemical stressors shape bacterial and antibiotic resistance gene (ARG) composition in microplastic-associated biofilms

We examined how polymer type, particle size, and exposure to bisphenol A (BPA) or heavy metals influence biofilm development, microbial community structure, pathogen presence, and antibiotic resistance gene (ARG) enrichment on microplastic and nanoplastic particles (MNPs). Four polymers (PP, PVC, PA, PET) in two size classes were incubated for eight weeks in freshwater mixed with treated wastewater, with or without BPA or metal mixtures. Over time, we quantified the bacterial abundance, the community composition (by 16S rRNA amplicon sequencing, and determined the presence of ARG and the opportunistic pathogens Legionella pneumophila, Mycobacterium avium, and Pseudomonas aeruginosa by qPCR.