Enzymatic degradation of plastic

Enzymatic degradation of plastic: Identification of polyethylene-degrading enzymes in Bacillus sp. YP1 and evolution of PET hydrolase for more efficient degradation of PET plastic

This project focused on investigating laccase from Bacillus subtilis subsp. subtilis str. 168 and PETase from Ideonella sakaiensis. Tania and Luba successfully cloned and expressed the laccase enzyme, confirming its activity in preliminary assays with syringaldazine and bromophenol blue. In parallel, they attempted to express Ideonella PETase.

As part of the funded project, the researchers cloned the copper-binding laccase from Bacillus subtilis subsp. subtilis str. 168, expressed the enzyme, and conducted activity assays. Copper-binding laccase enzymes are particularly valued for their role in the oxidation and degradation of polymers under mild conditions, making them promising candidates for sustainable plastic recycling. Concurrently, the researchers worked with PETase, a widely studied PET-degrading enzyme from Ideonella sakaiensis - known for its specificity in breaking down polyethylene terephthalate (PET) plastics into their monomer components. They obtained the PETase sequence from the Addgene database and attempted to express it. 

Although PETase was not detected on SDS-PAGE (suggesting low levels or the need for an alternative expression system), the team conducted activity assays using p-nitrophenyl acetate with clarified lysate and pellet fractions of the cell culture. These assays demonstrated an increase in hydrolase activity compared to controls, indicating the presence of active enzyme despite its low detectability on SDS-PAGE.