Soil Type Governs the Degradation Dynamics and Microbial Assimilation of Biodegradable Plastic Polybutylene Adipate Terephthalate.

Biodegradable plastics like polybutylene adipate terephthalate (PBAT) are increasingly marketed as alternatives to conventional plastics, yet how soil properties regulate degradation kinetics, how intact films and microplastic fragments differentially affect microbial communities, and which metabolic pathways and functional genes govern mineralization remain unclear. The present study investigated PBAT degradation mechanisms in 10 distinct agricultural soils by integrating metagenomics, microbial community analysis, and strain isolation. The results revealed that the environmental fate of PBAT is critically modulated by soil properties. Neutral-alkaline powdery loam soils exhibited the highest degradation efficiency. Soil physicochemical properties indirectly modulate PBAT weight loss by altering the gene abundance of hydrolases and aromatic-degrading enzymes, with soil nitrogen content serving as a key regulatory factor. Metagenomic correlation analysis suggests that PBAT degradation is associated with specific microbial consortia, including Hydrogenophaga and Ascomycota fungi. Microplastic particles of PBAT induced greater disturbances than intact films, as evidenced by significant reductions in microbial diversity, altered community structure, and shifts in functional gene composition. A complete degradation pathway, including initial polymer cleavage followed by terephthalic acid assimilation via the β-ketoadipate pathway, was elucidated. These results provide mechanistic insights into soil-specific PBAT degradation and facilitate risk assessment and sustainable management of biodegradable plastics.