Unraveling Microplastic-Biofilm Nexus in Aquaculture: Diversity and Functionality of Microbial Communities and Their Effect on Plastic Traits

Microplastics (MPs) serve as unconventional platforms for microorganisms and vectors for pollutants and pathogens in aquatic ecosystems. This study explored the dynamics of microbial colonization and biofilm formation on MPs, a key factor in their ecological impact, using five common MP types─poly(ethylene terephthalate) (PET), poly(vinyl chloride) (PVC), polyethylene (PE), polylactic acid (PLA), and polypropylene (PP)─incubated in an aquaculture pond for 128 days. The biofilm biomass increased by 173–617% compared with original samples, especially PP- and PE-MPs (OD 595 nm = 0.30 and 0.28, respectively). Driven by the inherent properties of MPs, biofilm biomass and microbial community structure differed significantly across the MP types, leading to varied changes in hydrophobicity and surface morphology. Differences in physicochemical properties cause each MP type to selectively enrich specific microbes, profoundly influencing biofilm formation and MP degradation potential. Notably, PP- and PE-MPs supported rich, mature biofilms conducive to carbon cycling and biofilm development, while PET-MPs attracted more abundant plastic degraders, like Pseudomonas. The study also highlighted the enrichment of pathogens on MPs, indicating potential environmental and human health risk. These findings illuminate the complex interactions between MP characteristics and biofilm dynamics, enhancing understanding of MPs' environmental behaviors and fates in aquatic settings.