Advancing PET-Degrading Enzymes through Directed Evolution to Combat Plastic Pollution

Plastic pollution poses a significant environmental challenge due to its persistence and widespread distribution. Among various types of plastic, polyethylene terephthalate (PET) is especially problematic due to its resistance to natural degradation. PET-degrading enzymes, particularly PETases and cutinases, have emerged as promising solutions for enzymatic plastic recycling. However, their native catalytic efficiency and thermostability are limited. Directed evolution has enabled the development of improved enzyme variants through techniques such as error-prone PCR, DNA shuffling, and saturation mutagenesis. This review highlights recent advances in engineering Cutinase and PETases, focusing on enhancing catalytic efficiency and thermostability for PET plastic degradation by directed evolution. Key engineered variants, including HotPETase and optimized leaf-branch compost cutinase (LCC) mutants, demonstrate significant progress toward sustainable plastic recycling through enzymatic means.