Polyethylene microplastics alter soil microbial community assembly and ecosystem multifunctionality

Although pervasive microplastics (MPs) pollution in terrestrial ecosystems invites increasing concern, impact of MPs on soil microbial community assembly, and ecosystem functions and multifunctionality received relatively little attention. Here, we manipulated a mesocosm experiment to investigate how polyethylene MPs (PE MPs; 0, 1%, and 5%, w/w) influence plant production, soil quality, microbial community diversity and assembly, enzymology in carbon (C), nitrogen (N) and phosphorus (P) cycling, and ecosystem multifunctionality in maize–soil continuum. Results showed that PE MPs exerted negligible effect on plant biomass (dry weight). The 5% PE MPs caused declines in the availability of soil water, C and P, whereas enhanced soil pH and C storage. The activity of C-cycling enzymes (α/β-1, 4-glucosidase, β-D-cellobiohydrolase) was promoted by 1% PE MPs, while that of β-1, 4-glucosidase was inhibited by 5% PE MPs. The 5% PE MPs reduced activity of N-cycling enzymes (protease and urease), whereas increased that of P-cycling enzyme (alkaline phosphatase). The 5% PE MPs shifted microbial community composition, and increased the number of specialist species, microbial community stability and networks resistance. PE MPs altered microbial community assembly, with 5% concentration decreasing dispersal limitation proportion (from 13.66 to 9.96%). Overall, soil ecosystem multifunctionality was improved by 1% concentration, while reduced by 5% concentration of PE MPs. The activity of α/β-1, 4-glucosidase, urease, and protease, and ammonium-N content were the most important predictors of soil ecosystem multifunctionality. These results underscore that PE MPs can alter soil microbial community assembly and ecosystem multifunctionality, thus development and implement of scalable solutions controlling soil MPs pollution become increasingly imperative in sustainable agricultural production.