Engineered FAST-PETase Variants for Accelerated Enzymatic Depolymerization of Post-Consumer Polyethylene Terephthalate

This study investigates engineered PETase enzyme variants for accelerated enzymatic depolymerization of post-consumer PET plastic within the context of enzyme engineering and polymer bioprocessing, an area of growing scientific importance given its implications for industrial-scale enzymatic PET recycling as part of closed-loop plastic circular economy systems. Using high-throughput colorimetric assay screening of 1,400 variants followed by HPLC-quantified depolymerization kinetics at 50 C, we examine serine hydrolase active site ester bond cleavage releasing TPA and EG monomers from the PET polymer chain in 12 PETase variants (from 1,400 screened) characterized by full kinetic and stability profiling drawn from controlled enzymatic reaction conditions at pH 7.2, 50 C with amorphous PET film substrate. Results indicate that lead variant FPv-11 achieves 99.4% amorphous PET depolymerization within 24 hours at 50 C and retains 78.4% activity on post-consumer bottle PET after a 72-hour incubation (p < 0.001), with 99.4% depolymerization within 24 hours as the primary quantitative benchmark. Concordance between primary and confirmatory measurement approaches exceeded 93%, validating the analytical framework. These findings contribute empirically to enzyme engineering and polymer bioprocessing and carry actionable implications for the design of programs and policies targeting industrial-scale enzymatic PET recycling as part of closed-loop plastic circular economy systems.