Enzyme-Assisted Depolymerization of Polymers

With the ever-increasing global demand for sustainable resources, the degradation of polymers, including synthetic plastics (e.g., polyethylene terephthalate (PET), polylactic acid (PLA)) and biomass (e.g., polysaccharides and lignin) has become a prominent issue. The stability of these materials in the natural environment makes them difficult to degrade, resulting in environmental pollution and/or resource wastage. To address this challenge, researchers have explored the use of enzymes as biocatalysts to facilitate the depolymerization of polymers. Enzymatic-assisted depolymerization has garnered attention due to its efficiency, specificity, and mild reaction conditions. This chapter reviews the latest advancements in enzymatic-assisted polymer depolymerization, focusing on the mechanisms and application potentials of various enzymes such as lipases, esterases, cellulases, lignin peroxidases, and chitosanase. It reveals the efficiency and selectivity of different enzymes in depolymerizing various types of polymers and evaluates their industrial application prospects. Moreover, the importance of enzymatic-assisted depolymerization in biomass-transforming agricultural waste and fishery by-products is discussed. Particularly, the paper discusses the engineering of enzymes to enhance enzyme stability and activity, highlighting its advantages in degrading microplastics. Finally, the paper emphasizes the importance of interdisciplinary technological innovations in promoting the commercialization of enzymatic-assisted depolymerization to achieve the sustainable circular utilization of polymer resources.