Streamlining biological recycling of poly(ethylene terephthalate) via pre-treatment methods

In this study, we validated various methods of pre-treatment of poly(ethylene terephthalate) (PET) by the engineered yeast Yarrowia lipolytica. This research compares both the effect of the type of plastic used, the processing method and enzymes with different mechanisms of action (PETase and cutinase). The investigation demonstrated that the degradation efficiency varies depending on the type of plastic used, the processing methods and the applied enzyme. Moreover, it indicated that during prolonged yeast culture under the applied conditions, enzyme activity is not impaired. Among all the methods tested, the artificial aging process had the greatest impact on the degradation level by PETase, where the amount of TPA released from commercial PET film was the highest, and yielded over 2 gL^-1. The maximum yield of TPA (0.59 gL^-1), for the Y. lipolytica strain overexpressing cutinase, was observed during the process with recycled PET bottles shredded into 1 mm fragments. The maximum recorded weight loss of plastic film is over 70% for commercial PET film subjected to artificial ageing process.