Deterministic assembly processes in the plastisphere community of biodegradable microplastics in farmland soil (PRJCA017428)

Biodegradable plastic (BP) is anticipated to become one of the most important strategies to alleviate plastic pollution. However, the colonization and assemblage of the bacterial communities on biodegradable microplastics (BMPs) surfaces in farming soil ecosystems are still little understood. Here, 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 biofilms. It was revealed that substrate type was the key factor determining the diversity and structure of bacterial community in biofilms, compared with fertilization practice. The bacterial alpha diversity of BMP biofilms were significantly lower than those of non-BMP biofilms (p < 0.05). Deterministic processes dominated the bacterial community assembly of microplastic biofilms in farmland soil. Higher contributions of deterministic processes were observed in BMP biofilms than in non-BMP biofilms. 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 shed insight on the peculiarities of bacterial community assembly mechanism on BMPs and have crucial implications for expediting the degradation of BMPs in soil ecosystems.