Stronger deterministic processes shape the plastisphere microbiota of biodegradable microplastics compared to non-biodegradable microplastics in farmland soil

Abstract

Biodegradable plastic (BP) is anticipated to become one of the most important strategies to alleviate plastic pollution. However, the colonization and assemblage of bacterial communities in biodegradable microplastic (BMP) plastisphere in farming soil ecosystems is still little understood. We carried out a field experiment in farmland soil with three fertilization practices to ascertain the differences in the bacterial community assembly between BMP and non-BMP plastispheres. We found that substrate type was the key factor determining the diversity and structure of bacterial communities in biofilms, in comparison with fertilization practice. The bacterial alpha diversity of BMP plastispheres was significantly lower than those of non-BMP plastispheres (p < 0.05). Deterministic processes dominated the bacterial community assembly of microplastic plastispheres in the farmland soil. Higher contributions of deterministic processes were observed in BMP plastispheres than in non-BMP plastispheres. Additionally, bacterial co-occurrence networks on BMPs were simpler and more unstable than those on non-BMPs, and some microorganisms with potential for degradation were identified as key taxa in bacterial co-occurrence networks of microplastics. Together, our findings provide insight on the peculiarities of bacterial community assembly mechanism on BMPs and a scientific basis for the application and management of biodegradable plastics in the future.