Comparing the bacterial composition, succession and assembly patterns in plastisphere and kitchen waste composting with PLA/PBAT blends

Biodegradable plastics has aroused increasing concern due to the negative environmental impact of plastic waste, however, the impact of biodegradable plastics mixed into kitchen waste (KW) on composting remains poorly understood, especially focusing on bacterial communities in the unique “plastisphere”. Here, KW composting for 120 days with adding poly lactic acid / poly butylene adipate-co-terephthalate (PLA/PBAT) plastics were conducted to reveal the dynamics of bacterial composition, succession, and assembly process in different ecological niches (compost and plastisphere). Results showed that the existence of PLA/PBAT plastics in composting would not significantly affect the safety and maturation of composts. After composting, 80% PLA/PBAT were degraded and there were prominent divergences of bacterial compositions between plastisphere, composts with PLA/PBAT and control. Co-occurrence network suggested that PLA/PBAT plastisphere exhibited higher network complexity and cohesion than that in compost, and PLA/PBAT increased bacterial module hubs, network hubs, and connectors in composting compared to control, but might enrich pathogens. Phylogenetic bin-based null model analysis indicated that stochastic processes obviously shaped the communities on PLA/PBAT plastisphere, but compare to control, PLA/PBAT plastics enhanced the contribution of deterministic processes on composting bacterial community assembly. These findings deeply understood the assembly patterns and diversity of plastisphere and composting processes, laying down a foundation on applying biodegradable plastics under the classification of domestic garbage.