Bacterial Colonization of Textile Microplastics in River Water and the Distribution of Antibiotic Resistance Genes

Microplastic fibers (MPFs) are a prevalent form of microplastics in aquatic environments, where they serve as substrates for bacterial colonization, including bacteria with antibiotic resistance genes (ARGs), which can then be spread throughout aquatic ecosystems. The present study investigates bacterial colonization on synthetic MPFs (Kevlar, acrylonitrile, polyester, nylon) and natural cotton fibers in river water. Bacterial attachment and taxonomic diversity were characterized using epifluorescence microscopy, scanning electron microscopy, and 16S rRNA sequencing. The presence and relative abundance of three common ARGs, blaNDM-1, blaKPC, and blaOXA-48, were assessed using quantitative PCR. Cotton exhibited highest levels of bacterial colonization and supported distinct taxonomic profiles compared to synthetic MPFs. Members of the families Saprospiraceae and Microscillaceae were significantly enriched on cotton fibers. ARGs were enriched in bacteria on all MPF types compared to cotton, with blaOXA-48, a widespread plasmid-associated gene, displaying highest relative abundance. Fluviicola, Sphingobium, Nitrospira, Schlesneria and TRA3-20 harbored blaNDM-1, blaKPC, and blaOXA-48 on all MPFs. These findings indicate that MPFs do indeed support bacteria with ARGs and thus may contribute to the environmental spread of antibiotic resistance within freshwaters.