The Spatiotemporal Successions of Bacterial and Fungal Plastisphere Communities and Their Effects on Microplastic Degradation in Soil Ecosystems

The succession and assembly processes of plastisphere microbiomes and their potential for the degradation of microplastics (MPs) in soil ecosystems are still unclear. We explored the variation of plastisphere microbiomes on three MPs over three time periods in three types of soil. Continuous alterations in the composition of plastisphere microbiomes were observed during incubation, and the successions of plastisphere microbiomes were significantly influenced by the colonization environment, followed by the polymer type and incubation time. The assembly of plastisphere microbiomes was dominated by stochastic processes; however, determinism contributed more to the assembly of plastisphere bacterial communities than to fungal communities, suggesting that the filtering effects of MPs on bacteria were stronger than those on fungi. The microbial communities in plastispheres exhibited networks of lower complexity and stability, as well as lower functional diversity, than the networks within bulk soils. Bacterial communities played a greater role in plastisphere microbial network formation and MP degradation than fungal communities. The MPs attracted and retained key microbes with a significantly higher organic carbon degradation capacity than soil microbes, causing plastispheres to become hotspots of organic carbon metabolism in soil. This study deepens our understanding of the mechanisms of the formation and succession of soil plastispheres.