Polyester-degrading enzymes in a circular economy of plastics

With only a fraction of plastic waste being recovered and the majority incinerated, landfilled or released into the environment, plastic is increasingly accumulating in aquatic and terrestrial ecosystems, leading to widespread pollution. Biocatalysis offers a route to the sustainable recycling of synthetic polyesters, such as polyethylene terephthalate (PET), which is commonly used in textiles, food and beverage packaging, representing a major source of plastic waste. In particular, polyester hydrolases can deconstruct recalcitrant synthetic polymers at scale. This Review discusses the role of biocatalysis in a circular economy of plastics, outlining enzymatic modification and deconstruction strategies for synthetic polyesters. Moreover, protein engineering and computational approaches are examined to design and optimize polyester hydrolases for large-scale recycling in key industrial applications. Finally, the importance of economic viability is highlighted, including strategies to make biocatalysis a cost-effective and sustainable plastics recycling strategy. Plastic pollution could be partly addressed through the biocatalytic recycling of plastic waste streams. This Review discusses the identification and optimization of polyester-degrading enzymes for the large-scale recycling of plastic waste.