The Aquatic Plastisphere: Methodology, Biofilm Formation Mechanism, and Microbial Diversity

From 2019 to 2060, the amount of plastic accumulated in the aquatic environment is expected to increase from 140 million tons to 493 million tons. The continuous release of microplastics (MPs) into the environment has negatively impacted aquatic ecosystems. MPs tend to develop biofilms on their surface in natural waters, and this new micro-ecosystem created by man-made plastic pollution is called plastisphere. The biofilm modifies the migration, transformation and fate, biological effects, and degradation processes of MPs. Although there have been numerous studies on MP biofilm, most focus on microbial diversity and structure. In addition, there are relatively few comprehensive descriptions of biofilm formation and research methods. In this paper, we review the recent works on microbes in the plastisphere, describe microbial interactions in the plastisphere, and examine the research methods, their benefits, and drawbacks concerning MP biofilms, and the four primary environmental factors (nutrient conditions, water temperature, the flow state of water, salinity) that influence microbial colonization. Next, we illustrate the whole process of how microorganisms colonize the MP surface. Finally, we study the microbial community of plastisphere in freshwater, marine, and wetland environments, and provide an outlook for future biofilm research on MPs.