Biofilm formation and its implications on the properties and fate of microplastics in aquatic environments: A review

Particulate plastic fragments (micro and nano-plastics) in aquatic environments provide abundant solid substrates, which serve as an important habitat for a variety of microorganisms. Surfaces of microplastics (MPs) exhibit hydrophobicity that facilitate the adsorption of dissolved organic carbon (DOC) in the aquatic environment. Furthermore, MPs act as substrata, as well as a carbon source including the readily bioavailable DOC, which promote the formation of microbial biofilms. These biofilms have varied metabolic actions that govern the subsequent succession of micro- and meso-organisms habitation of MPs. The assemblage of ecosystems colonising the plastic environment is often referred to as the “plastisphere”. Polymer type, environmental conditions, including nutrient status, salinity, and season, affect the microbial composition of the biofilm. Microbial habitation accelerated by biofilm formation on particulate plastics enables the movement of microorganisms, especially in the aquatic environment, and impacts the transport and toxicity of contaminants associated with these particulate plastic fragments. This review paper describes the processes of microbial habitation and subsequent biofilm formation, the factors affecting biofilm formation, and the implications of biofilm formation on the mobility of microorganisms, degradation of MPs, and the bioavailability of contaminants associated with MPs.