Microbial Diversity of the Surface of Polypropylene and Low Density Polyethylene-Based Materials (Plastisphere) From an Area Subjected to Intensive Agriculture

Abstract

Accumulation of synthetic plastics in the biosphere has led to global pollution, provoking serious consequences for the environment and human health. Uncontrolled agricultural plastic landfills have the risk of becoming a source of agrochemicals and microplastics. Biotechnological approaches to solve plastic pollution include the removal of these polymers through biological degradation, which is a friendly environmental method. The microbial communities colonizing plastic debris (plastisphere) are considered as a potential source of plastic-degrading microorganisms. In this study, a bacterial biodiversity analysis, based on 16S rRNA gene-targeted metagenomic sequencing, was achieved in the plastisphere of low-density polyethylene (LDPE) and polypropylene (PP) polymers from an agricultural landfill. The α-diversity analysis did not show significant differences between LDPE and PP plastispheres and the plastic-free bulk soil, while LDPE and PP bacterial communities clustered close, but separately from the bulk soil in a β-diversity analysis. Although the taxonomic composition of both plastispheres was different, they shared a significantly higher proportion of Cyanobacteria and Deinococcota than the bulk soil. Additional analyses showed different indicator families, genera and species that can be associated with plastispheres. A predictive functional analysis suggests that degradation of plastic additives in both plastispheres is probably occurring. In addition, the existence of degradation processes for specific herbicides in each plastisphere is highlighted, and the possible exposure of LDPE to both physical and biological degradation processes is also described. These results will contribute to characterize the soil plastisphere exposed to different environmental conditions, and to understand the specific biological niches where plastic-degrading microorganisms could survive.