High-Efficiency Biocatalytic Degradation of Polyethylene Terephthalate via Engineered Biopolymer-Immobilized Enzymes for Sustainable Plastic Recycling

The accumulation of polyethylene terephthalate (PET) plastic waste presents a pressing global challenge to environmental sustainability, demanding innovative treatment strategies. Enzyme-enabled PET degradation and recycling have emerged as a promising eco-friendly and cost-effective alternative to conventional methods. In this study, we developed a one-pot biosynthetic approach to engineer Escherichia coli for in vivo immobilization of PET-hydrolyzing enzymes (PHEs), FAST-PETase, TurboPETase, and LCCICCG, onto biopolymeric polyhydroxyalkanoate (PHA) granules, constructing three corresponding PHE–PHA biocatalysts: FAST-PETase-PHA, TurboPETase-PHA, and LCCICCG-PHA. Among them, TurboPETase-PHA and LCCICCG-PHA exhibited superior PET degradation performance under mild conditions (60–65 °C, pH 8), along with notable thermostability, excellent storage stability, and reusability across multiple PET depolymerization cycles. These biocatalysts achieved near-complete depolymerization of various postconsumer PET products. Remarkably, gram-scale recovery of high-purity terephthalic acid with ∼90% yield was demonstrated through postconsumer PET waste depolymerization by LCCICCG-PHA. Techno-economic analysis and life cycle assessment further indicated the economic feasibility and environmental advantages of this biocatalytic platform compared to existing PET treatment technologies. This work underscores the potential of synthetic biotechnology to enable sustainable high-performance solutions for plastic waste management and to advance a circular plastic economy.