Interactions between microplastics and microorganisms in the environment: Modes of action and influencing factors

The widespread presence of microplastics (MPs) in the environment has led to the rise of the study on the interaction between MPs and microorganisms. The variety and characteristics of MPs in the environment make their interaction with microorganisms more complex. Recent studies have found that MPs can also serve as an important carrier for microorganisms to form fully developed biofilms on the substrates. The emergence of new ecological sites will also affect the ecosystem of water and soil. We present the latest knowledge of MPs' interactions with microorganisms and summarize their respective potential impacts on the environment. It was found that the main factors affecting microbial colonization on MPs were the characteristics of MPs, exposure time and environmental factors. Furthermore, microbial colonization on MPs can affect the composition and distribution of the microbial community in the environment, as well as the migration and transformation of other contaminants which also occur in the animal guts. When it come to the toxicity of MPs to microorganisms, it has been found that the main effects of MPs on microorganisms are the effect on microbial growth, photosynthesis of microorganisms and some single cells. In addition, the combined effects of MPs with heavy metals and organic compounds on microorganisms can be divided into antagonistic effects, synergistic toxicity, promoting effects and non-effects. In turn, microbes will have impacts on MPs in terms of degradation, absorption, transfer and deposition. In practical application, MPs will affect the biological treatment stage of sewage treatment. This review discusses the interaction mechanism and influencing factors between microorganisms and MPs. It also called for active exploration of methods for treating MPs with microorganisms in the actual environment, providing a theoretical basis for the treatment of microorganisms, and a better understanding of the environmental behavior and ecological risk assessment of MPs.