LDPE microplastics affect soil microbial community and form a unique plastisphere on microplastics

As emerging contaminants, the ecological impact of microplastics has attracted worldwide attention because of the limitations of recycling technology and their long durability, leading to their accumulation in the environment and the potential risk to human health. In this study, we investigated the effects of PE microplastics (1 % and 5 % w/w) on soil physicochemical properties, enzyme activity, and microbial community. The addition of PE microplastics pollution promoted the activities of urease and fluorescein diacetate hydrolase (FDAse), whilst the activity of neutral phosphatase was inhibited. The addition of PE microplastics did not significantly affect soil microbial community alpha diversity, however, soil microbial community composition was altered. The 1 % (w/w) PE microplastics significantly influenced the relative abundance of Arthrobacter and norank_f_Gemmatimonadaceae, and 5 % (w/w) PE microplastics significantly reduced the relative abundance of Arthrobacter, Nocardia, Bacillus and Blastococcus. The environmental factor correlation analysis revealed that pH as well as soil organic carbon and total nitrogen significantly affected the structure of soil bacterial communities at the phylum and genus level, respectively. Particularly, the dominant species on the surface of the microplastics were Nocardia, Aeromicrobium, Amycolatopsis and Rhodococcus, which were remarkably different from those in soils. These bacterial taxa were related to the degradation of microplastics, as well as transmission of diseases and resistance genes. This work demonstrated the influence of PE microplastics on soil ecology, suggesting that microplastics in soils can act as a distinct microbial habitat which can potentially alter the ecological functions of soils.