Engineering material-binding peptides to accelerate enzymatic degradation of polylactic acid

The global demand for plastics continues to surge, driven primarily by population growth and urbanization. Modern lifestyles, characterized by convenience and time constraints, have led to an increased reliance on disposable items, many of which are made from plastics. Plastics can be broadly categorized into petrochemical-based and bio-based plastics. Among bioplastics, PolyLactic Acid (PLA), primarily derived from renewable resources like corn and starch, stands out. In 2022, the global demand for PLA exceeded 490 thousand tons, accounting for approximately 20-25% of the global bioplastics production capacity, making it the most widely produced bioplastic by volume. This project aims to develop a biological method for degrading PLA, leveraging the advantages of ambient temperature and pressure conditions, thereby eliminating the need for energy-intensive processes. The approach enhanced PLA degradation efficiency through the use of material binding peptides fused with degradation enzymes to increase its contact with PLA. Initially, the MBP Cg-Def was selected for its superior PLA binding performance. Molecular Dynamics Simulations identified beneficial variants with improved PLA binding, D26K and G23H. These variants were subsequently recombined to create a double-mutated peptide Cg-Def G23H/D26K, resulting in a 1.47-fold improvement in PLA binding. Following a thorough literature review, three enzymes, ICCG, FAST-PETase, and RPA1511, were chosen for their high polyester degradation efficacy in previous studies. These enzymes were fused with the Cg-Def variants to enhance their PLA degradation rates. Finally, their PLA degradation performance was compared using nanoparticles of the two PLA isomers, poly-L-lactic acid and poly-D-lactic acid. The combination of MBPs with enzymes demonstrated improved PLA degradation rate, highlighting the potential of this method as an environmentally friendly alternative to traditional plastic degradation techniques. This approach not only helps reduce the environmental impact of PLA waste but also offers a scalable solution for managing the growing volume of bioplastics in various industries. Future research will focus on optimizing the fusion proteins for large-scale applications and exploring their efficacy across different types of bioplastic materials, thereby broadening the scope of sustainable plastic degradation technologies.