Biochemical Characterisation of Sis: A Distinct Thermophilic PETase with Enhanced NanoPET Substrate Hydrolysis and Thermal Stability.

Polyethylene terephthalate (PET) degradation by enzymatic hydrolysis is significant for addressing plastic pollution and fostering sustainable waste management practices. Identifying thermophilic and thermostable PET hydrolases is particularly crucial for industrial bioprocesses, where elevated temperatures may enhance enzymatic efficiency and process kinetics. In this study, we present the discovery of a novel thermophilic and thermostable PETase enzyme named Sis, obtained through metagenomic sequence-based analysis. Sis exhibits robust activity on nanoPET substrates, demonstrating effectiveness at temperatures up to 70 °C and displaying exceptional thermal stability with a melting temperature (T m ) of 82 °C. Phylogenetically distinct from previously characterised PET hydrolases, Sis represents a valuable addition to the repertoire of enzymes suitable for PET degradation.