Bio-upcycling PET waste: Advances in enzymatic hydrolysis and biosynthesis of value-added products.

With excellent mechanical properties and chemical stability, poly (ethylene terephthalate) (PET), an engineering plastic, is widely applied in textiles and packaging. However, the widespread use and low biodegradability of PET have resulted in significant environmental pollution. Recent advances in PET hydrolase discovery and engineering have driven the rapid advancement of PET bio-recycling, while efficient PET hydrolases can depolymerize PET into monomers under mild conditions, providing a sustainable approach to potentially addressing the plastic pollution issue. However, PET enzymatic hydrolysis still faces some technical challenges, such as poor stability of the hydrolases and low efficiency in degrading high-crystalline PET. Thus, this review summarizes recent advances in strategies to enhance the efficiency of PET enzymatic hydrolysis and explores the interplay of factors affecting PET hydrolysis efficiency. Furthermore, we highlight the progress in metabolic engineering approaches for the biotransformation of PET degradation products into higher value chemicals, providing insights into achieving efficient PET bio-recycling. This review systematically integrates key factors for enhancing the PET enzymatic hydrolysis efficiency and showcases successful examples of PET waste further valorization, providing valuable references and insights for the industrialization of PET bio-upcycling.