Message in a Bottle: the Expression and Confirmation of ISF6_4831, a Polyethylene Terephthalate Hydrolase

Polyethylene terephthalate (PET), the polyester used to make plastic bottles for soft drinks, is one of the top five sources of plastic waste in the world. Its abundance represents significant problems for municipalities and environments. Recycling PET polymers by traditional methods is possible, but success has been limited due to poor compliance, liability, cost, and other factors. Fortunately, a PET degradation pathway has been identified in Ideonella sakaiensis. Research on this pathway is still nascent and has not yet explored the PET hydrolase gene (ISF6_4831, or PETase) with its leading signal peptide intact. For this reason, the gene was transferred into Escherichia coli with subsequent expression and confirmation by PCR, SDS PAGE, Sanger sequencing, and Western blot. Apparent striking pink hues in the resultant growth media suggest that the secretion signal found in the gene is functional in E. coli and that the protein may hydrolyze some similar non-native substrates. This is noteworthy because it implies the potential for the gene moving laterally through environments rich in plastic waste without human intervention. We follow up by discussing some of the environmental and ecological implications of this and reviewing future directions for exploring this largely undocumented phenomenon.