Development and characterization of a bacterial enzyme cascade reaction system for efficient and stable PET degradation

The widespread use of polyethylene terephthalate (PET) in various industries has led to a surge in microplastics (MPs) pollution, posing a significant threat to ecosystems and human health. To address this, we have developed a bacterial enzyme cascade reaction system (BECRS) that focuses on the efficient degradation of PET. This system harnesses the Escherichia coli (E. coli) surface to display CsgA protein, which forms curli fibers, along with the carbohydrate-binding module 3 (CBM3) and PETases, to enhance the adsorption and degradation of PET. The study demonstrated that the BECRS achieved a notable PET film degradation rate of 3437 ± 148μg/(d*cm²), with a degradation efficiency of 21.40% for crystalline PET MPs, and the degradation products were all converted to TPA. The stability of the system was evidenced by retaining over 80% of its original activity after multiple uses and during one month of storage. Molecular dynamics simulations confirmed that the presence of CsgA did not interfere with the enzymatic activity of PETases. This BECRS represents a significant step forward in the biodegradation of PET, particularly microplastics, offering a practical and sustainable solution for environmental pollution control. Environmental Implication Polyethylene terephthalate (PET) is a commonly utilized material in food packaging and various industries. Nevertheless, its disposal can have detrimental effects on the environment and human health as it transforms into microplastics in terrestrial and aquatic ecosystems. In response to the pressing global concern of PET pollution, we have introduced a novel whole-cell degradation system designed to effectively break down PET and its microplastics. This system involves the utilization of Escherichia coli that co-display binding and degradation modules on their surface while expressing a hydrolysis module internally. The strategy exhibits the robust repeatability and long-term storage stability of PET hydrolases.