Microbes’ and Microplastics’ Interactions in Freshwater Ecosystems: Fate and Implications for Environmental Health .

Abstract

Microorganisms play a pivotal role in the biogeochemical cycles of aquatic environment, mediating interactions between biotic and abiotic components and forming complex associations with plastic debris. Their widespread distribution is a global concern due to their movement through food chains, which poses risks to ecosystems and human health, and their capacity to facilitate the spread of infectious microbes in contaminated nvironments. Interactions between micro organisms and microplastics (MPs) can yield both beneficial and harmful effects. Microorganisms, including bacteria, fungi, algae, and viruses are indispensable for nutrient cycling, organic matter decomposition, microplastic degradation, and maintaining overall ecosystem health. Certain bacterial groups, such as Proteobacteria, Cyanobacteria, and Bacteroidetes, are commonly associated with MPs like polyethylene (PE) and polypropylene (PP), while plastics like polyvinyl chloride (PVC) and polystyrene (PS) are less frequently colonized. These bacteria play a crucial role in breaking down large polymer molecules into smaller components and monomers, ultimately leading to mineralization into CO₂, H₂O, and biomass via enzymatic processes. The intricate relationships between microorganisms and microplastics, including microbial colonization, biofilm formation on MPs (commonly referred to as the plastisphere), biodegradation mechanisms, and their broader implications for pollution dynamics and ecological health, underscore the complexity of the issue. While microbial degradation of microplastics offers potential solutions, it faces significant challenges. Despite these challenges, understanding the mechanisms of microbe-MP interactions and their environmental implications remains critical for developing strategies to combat microplastic contamination in freshwater ecosystems. This chapter explores these interactions in detail, focusing on the dual role of micro organisms in mitigating and exacerbating MP-related pollution. By advancing research on microbial processes and environmental variables that influence plastic degradation, it is possible to work toward innovative solutions for managing microplastic contamination and safeguarding environmental health