Acceleration a Yeast-based Biodegradation Process of Polyethylene Terephthalate Microplastics by Tween 20: Efficiency, By-Product Analysis, and Metabolic Pathway Prediction

Polyethylene terephthalate is a widely produced plastic polymer that exhibits considerable biodegradation resistance, making its derived microplastics ubiquitous environmental pollutants. In this study, a new yeast strain (Vanrija sp. SlgEBL5) was isolated and found to have lipase and esterase-positive capabilities for degrading polyethylene terephthalate microplastics. This isolate changed the microplastic surface charge from -19.3 to +31.0 mV and reduced more than 150 μm of its size in addition to reducing the intensity of the terephthalate, methylene, and ester bond functional groups of the polymer. Tween 20 as a chemical auxiliary treatment combined with biodegradation increased the microplastic degradation rate from 10 to 16.6% and the thermal degradation rate from 85 to 89%. Releasing less potentially hazardous by-products like 1,2 diethyl-benzene despite the higher abundance of long-chain n-alkanes, including octadecane and tetracosane was also the result of the bio+chemical treatment. Altogether, the findings showed that Vanrija sp. SlgEBL5 has potential as a biological treating agent for polyethylene terephthalate microplastics, and the simultaneous bio+chemical treatment enhanced the biodegradation rate and efficiency.