Genetically engineered Escherichia coli: The new recyclers of PET plastic waste

Polyethylene terephthalate (PET) pollution is a significant environmental concern due to the polymer's widespread application, pronounced crystallinity, and intrinsic resistance to biodegradation. Although certain wild-type microorganisms demonstrate PET-hydrolyzing capabilities, their industrial applicability is constrained by slow proliferation, suboptimal catalytic performance, and limited resilience under environmental stress. These challenges highlight the imperative for engineered microbial platforms mediating robust, in situ PET depolymerization. This review discusses the emergence of genetically engineered Escherichia coli (E. coli) as a promising and versatile chassis for PET bioconversion. PETases and related hydrolases have been heterologously expressed and subjected to iterative protein engineering in E. coli to improve thermal stability, catalytic turnover rates, and substrate selectivity. In parallel, synthetic biology strategies have enabled the modular assembly of multi-enzyme cascades and surface display systems to enhance microbe-PET interfacial interactions and catalytic efficiency. Furthermore, integration of native and synthetic metabolic circuits within E. coli enables the biotransformation of ethylene glycol (EG) and terephthalic acid (TPA) into central metabolites, which are subsequently directed toward the biosynthesis of a diverse array of high-value bioproducts.