Core Viewpoint - The article discusses advancements in enzymatic hydrolysis and biosynthesis of value-added products from PET waste, highlighting the importance of biological recycling methods in addressing global plastic pollution and enhancing the economic viability of PET recycling [2][4][27]. Group 1: PET Waste and Environmental Impact - The global production of PET reached 88.1 million tons in 2022, with significant waste accumulation due to its non-biodegradable nature and inefficient recycling methods [3]. - Traditional mechanical and chemical recycling methods face limitations, while biological recycling offers a more environmentally friendly and energy-efficient alternative [4][16]. Group 2: Enzymatic Hydrolysis Mechanism - PET is hydrolyzed into its monomers, ethylene glycol (EG) and terephthalic acid (TPA), through the action of specific enzymes, primarily carboxylesterases [5][7]. - The hydrolysis process involves two main steps: acylation and deacylation, facilitated by the enzyme Is PETase, which has gained attention for its efficiency at ambient temperatures [5][7]. Group 3: Enhancing Enzymatic Efficiency - Strategies to improve PET hydrolysis efficiency include enzyme engineering, substrate pretreatment, and optimization of reaction conditions [8][14]. - Enhancing the thermal stability of PET hydrolases allows for more effective catalysis near PET's glass transition temperature, which is crucial for improving substrate accessibility [9][11]. Group 4: High-Value Conversion of PET Products - The hydrolysis products TPA and EG can be converted into high-value chemicals through metabolic engineering, significantly increasing the economic feasibility of PET recycling [17][20]. - Various microorganisms can metabolize TPA into valuable products such as polyhydroxyalkanoates (PHA) and vanillin, while EG can be assimilated into central metabolic pathways for the production of various chemicals [18][20]. Group 5: Economic and Process Considerations - The economic viability of enzymatic PET recycling is influenced by factors such as degradation efficiency, substrate load, and enzyme costs, which directly affect product yield and purity [16][28]. - A comprehensive optimization approach that includes both enzyme performance and process system improvements is essential for achieving sustainable and efficient PET recycling [16][27].