ABSTRACT
As a widespread pollutant in the environment, research on microplastics have attracted much attention. This review systematically analyzed the interaction between microplastics and soil microorganisms based on existing literatures. Microplastics can change the structure and diversity of soil microbial communities directly or indirectly. The magnitude of these effects depends on the type, dose and shape of microplastics. Meanwhile, soil microorganisms can adapt to the changes caused by microplastics through forming surface biofilm and selecting population. This review also summarized the biodegradation mechanism of microplastics, and explored the factors affecting this process. Microorganisms will firstly colonize the surface of microplastics, and then secrete a variety of extracellular enzymes to function at specific sites, converting polymers into lower polymers or monomers. Finally, the depolymerized small molecules enter the cell for further catabolism. The factors affecting this degradation process are not only the physical and chemical properties of the microplastics, such as molecular weight, density and crystallinity, but also some biological and abiotic factors that affect the growth and metabolism of related microorganisms and the enzymatic activities. Future studies should focus on the connection with the actual environment, and develop new technologies of microplastics biodegradation to solve the problem of microplastic pollution.
Subject(s)
Microplastics , Plastics , Soil , Polymers , Biodegradation, EnvironmentalABSTRACT
Sulfonamides (SAs) are a kind of antibiotics widely used in medical treatment and livestock breeding. However, they have poor degradability in human and animal intestines, and will enter the sewage treatment system through the discharge of feces and urine. The aerobic activated sludge (AAS) in wastewater treatment plant was found to be able to effectively transform SAs. This article summarizes the advances in biodegradation of SAs in aerobic activated sludge system, which includes the biodegradation mechanisms, the main biodegradation pathways, and the environmental factors affecting the degradation efficiency. Challenges encountered in the current research were discussed, with the aim to provide scientific basis for optimizing the biodegradation of SAs in wastewater treatment process.