Engineered Yeasts Displaying PETase and MHETase as Whole-Cell Biocatalysts for the Degradation of Polyethylene Terephthalate (PET).

Due to its low cost of manufacturing, poly(ethylene terephthalate) (PET, a polyester plastic) has been the most widely used plastic material for food packaging. However, PET is nonbiodegradable. It can take years to degrade when it is discarded into the environment. In recent years, plastic pollution has received much attention and has become a major environmental issue. In this study, we engineered yeast surfaces to display two PET-degrading enzymes (PETase and MHETase) to degrade PET plastics. The enzymes displayed on the yeast surface were characterized by using confocal microscopy and flow cytometry. The reaction conditions to degrade PET plastics using the engineered yeasts were optimal at pH 9 and 30 °C. In addition, the engineered yeasts showed great stability and reusability to degrade PET films. Furthermore, we demonstrated that the engineered yeasts as whole-cell catalysts can be used to degrade drinking water bottles into value-added products. This study provides a novel whole-cell biocatalyst using engineered yeasts to degrade plastic waste, offering a new strategy to solve plastic pollution and recycling challenges.