Incubation habitats and aging treatments affect the formation of biofilms on polypropylene microplastics

Microbial colonization and biofilm formation associated with microplastics (MPs) have recently attracted wide attention. However, little is known about the effect of MP aging and different exposed habitats on biofilm formation and associated microbial community characteristics. To obtain a comprehensive understanding, virgin and aged polypropylene MPs were selected as attachment substrates and exposed to different aquatic habitats (marine, estuary, and river). The results showed that the aging process could destroy surface structure and increase oxygen-containing groups of MPs. The total biomass of the biofilms, attached-bacterial OTU numbers, and alpha diversities increased with exposure time. The biofilms biomass and alpha diversity of MPs in the river were significantly higher than those in the marine and estuary habitats, and temperature and salinity were primary factors affecting microbial colonization. Bacterial communities in MP-attached biofilms were significantly different from those in surrounding water. Microorganisms tend to adhere to aged MPs, and especially, genes related to human pathogens were significantly expressed on aged MPs, suggesting a potential ecological and health risk of aged MPs in aquatic ecosystems. Our results showed that aged MPs and different habitats have an important influence on microbial colonization, and the weathering process can accelerate biofilm formation on MPs.

Automated summary

This study explores the effects of microplastic aging and different aquatic habitats on biofilm formation and microbial community characteristics. The results indicate that aging can alter the surface structure and increase oxygen-containing groups of microplastics. The total biomass and alpha diversity of biofilms increase with exposure time. Microbes tend to adhere to aged microplastics, and genes related to human pathogens are expressed on aged microplastics. The study highlights the importance of aged microplastics and different habitats in microbial colonization and suggests potential ecological and health risks.