Peroxygenase Engineering for Studies on Degradation of Complex Epoxy Materials

Abstract

Due to the current end-of-life of thermoset composites, which mainly comprises incineration and landfill storage, is of utmost necessity to find sustainable biodegradation methods. In the present work, we approach enzymatic degradation of epoxy resins by exploiting fungal peroxygenases’ (UPOs) versatility in terms of C-H oxyfunctionalization reactions. Aiming at engineering UPOs through directed evolution towards epoxy resins biodegradation, a colorimetric high-throughput screening assay was developed based on the hydroxylation of the model molecule 1-phenoxy-2- propanol; the main structural scaffold of Araldite/Aradur epoxy resin. Employing the evolved UPO variant GroGu as parental type, we were able to identify and characterized several mutants with improved activity in the degradation of the model compound. Further directed evolution rounds will be needed to obtain one final variant that will be subjected to lab-scale degradation studies with the real material, setting out the bases for a more sustainable end-of-life management of thermoset plastics.