Plastic residues alter soil microbial community compositions and metabolite profiles under realistic conditions

Abstract

Wide usage of plastic coupled with mismanagement has created a humongous environmental hazard threatening entire ecosystems. To date, the potential effects of plastic debris-induced soil nutrition substance changes and the relevant microbial metabolic behavior remain unclear. Here, we studied the effect of plastic films polyethylene and polylactic acid in differential soil environments (farmland, woodland, and wetland) for 120 days. Soil enzyme activities (urease, neutral phosphatase, and catalase) and nutrition substance (NH4+-N, available P, available K, and soil organic matter) present obvious variations in polylactic acid groups compared to polyethylene-treated samples. 16S rRNA gene sequencing indicates that several bacteria abundance such as Bacteroidales, Actinobacteriota, Nitrososphaeraceae, Pyrinomonadalcs, Muribaculaceae, exhibited obvious up-regulation or down-regulation, and simultaneously, the carbon, nitrogen, and phosphorus cycling relevant species Bryobacter, Bradyrhizobium, and Sphingomonas, expressed wider margin of down-regulation in abundance in plastic treatment soil samples. As a result, the abundance of metabolites including sugar, amino acid, and fatty acids, which may associated with nutrition substance metabolic pathways, were significantly altered in the stress of plastic. These findings provide valuable information on the environmental effects of plastics, and the relationships of subsequent nutrition substance changes and microbial metabolic behavior.