Impact of Microplastics on Microbial Diversity in Riparian Soils and on Microplastic Surfaces

The effects of microplastics (MP) on microbial community diversity in non-agricultural, terrestrial environments are uncertain, particularly in riparian soils. This experimental study is focused on microbiome community structure in riparian soils in North American—particularly north-central Illinois—freshwater wetlands and prairie biomes, both affected and unaffected by MP, as well as community structure on MP particles. The MP studied are widely used plastics, including polyester microfiber (MF), polyethylene (PE), polypropylene (PP), and polystyrene (PS). The presence of MP altered the diversity of the soil microbial community, including the relative abundance of key taxa involved in methane and nitrogen cycling, and increased the abundance of possible plastic degrading taxa. Taxa involved in methane and nitrogen cycling also colonized MP surfaces under experimental conditions, varying by the MP type and across sites from which the soil was extracted. Understanding the trends in taxa that colonize the MPs as opposed to those in the soils is useful in determining the impact MP pollution might have on the various biogeochemical cycles in this terrestrial environment.