Responses of bacterial communities to microplastics: More sensitive in less fertile soils

Recently, the potential impact of microplastics (MPs) on bacterial communities has risen enormously attention due to the increasing amount of plastic waste generated nowadays. However, there is a lack of clarity due to limited studies on the responses of bacterial communities to MPs exposures in various soil ecosystems. Here, we conducted a soil microcosm experiment to analyze the potential impact of MPs on bacterial communities in farmland soil, forest soil, and sandy soil. The changes in alpha/beta diversity and co-occurrence network of bacterial communities were more significant in farmland soil amended with PS MPs (5 g kg^-1), forest soil amended with PP MPs (5 g kg^-1), and sandy soil amended with PP MPs (1 g kg^-1). Particularly, the bacterial communities in sandy soil with the least soil organic carbon content were disturbed most significantly compared to other treatments. LEfSe analysis revealed that specific bacterial taxa such as phylum Proteobacteria, Actinobacteria, Firmicutes, and genus Sphingomonas, Candidatus Udaeobacter, Gemmatimonas, were sensitive to MPs exposures. Functional annotation showed that perturbation of bacterial communities was related to organic carbon decomposition, nitrogen fixation, nitrate reduction/respiration, etc. In sum, MPs may potentially affect bacterial community structure and functions relevant to carbon/nitrogen cycles at long-term realistic field exposure.