Functional potential of plastic-associated microorganisms

Plastics exposed to the marine environment are rapidly colonised by diverse microbial communities, which can potentially influence the biological and physicochemical interaction of plastics with the surroundings and their ecotoxicological properties. Factors affecting the composition and metabolic functioning of plastic-associated microbial communities (plastisphere) are poorly understood, especially with regard to whether different microbial communities systematically colonize different plastics. In this study, we employed a shotgun metagenomics approach to investigate the role of substrate type on plastisphere composition and functional role. Microbes associated with plastics were taxonomically distinct from the surrounding picoplankton. Genes required to adapt to a surface-associated lifestyle were enriched on the surface: functional analysis revealed a higher abundance of antibiotic and metal resistance genes associated with different plastics, and genes associated with horizontal gene transfer, quorum sensing, responses to oxidative stress and xenobiotic degradation were enriched on all plastics. Our results therefore indicate that plastisphere communities have the potential to influence the fate of marine plastics by harbouring specific microorganisms and genes that alter biodegradation. The selective enrichment of antimicrobial and toxic compound resistance genes on plastics also raises concern for unexpected impacts of plastics on the marine ecosystem.