Discovery of a polyesterase from Deinococcus maricopensis and comparison to the benchmark LCCICCG suggests high potential for semi- crystalline post-consumer PET degradation

Plastic pollution remains a significant environmental challenge, with conventional waste management strategies proving insufficient in addressing the problem. Enzymatic degradation has emerged as a promising alternative, with LCC^ICCG, an engineered metagenome-derived cutinase, being the most effective in degrading polyethylene terephthalate (PET), the most commonly produced and discarded polyester. However, more efficient PET-hydrolases are needed for the upscaling of a PET-waste biorefinery. In this regard, the study reports the characterization of a novel, phylogenetically distinct, thermophilic polyesterase from Deinococcus maricopensis (DmPETase) and its comparison to LCCICCG. DmPETase is capable of degrading various synthetic polymers, including PET, polyurethane, as well as four semi- crystalline aliphatic polyesters. DmPETase was found to be comparable to LCC^ICCG at 50 °C in degrading semi-crystalline sections of post-consumer PET bottles, but it appeared to be less sensitive to crystallinity degree increase. This property makes DmPETase a new template for protein engineering endeavors to create an efficient biocatalyst to be integrated into the bio-recycling process of PET waste, without the need for amorphization of the materials.