The Impact of Protein Content and Fouling on Enzymatic Degradation of Polyethylene Terephthalate

Enzymatic and microbial depolymerization of plastic is emerging as a promising method for recycling plastics. This paper looks into the effects of household and laboratory contamination on waste plastic and the implications these have on the enzymatic degradation of PET. Specifically, we find that exogenous protein, whether initially contaminating the surface of the plastic substrate or present in the enzymatic hydrolysis reaction buffer, can substantially inhibit the degradation of PET. The degree of inhibition varied based on the type of protein as well as the type of PET hydrolyzing enzyme used. Several wash solutions were applied after surface fouling and shown to improve degradation and in some cases, restoring levels to that of unfouled plastics. Collectively, these findings can enable a better understanding of factors that influence enzymatic depolymerization including industrial pre-processing as well as have implications for in situ degradation.