Enhanced Biodegradation of Waste Poly (Ethylene Terephthalate) Exploiting Carboxylesterases Complex

다국어 초록 (Multilingual Abstract)

Polyethylene terephthalate (PET) triggers environmental issues since it is hard to degrade due to its recalcitrant and hydrophobic properties. In this study, we suggest a novel PET degrading complex that possesses improved stability and binding ability toward PET for continuous degradation of PET. The complex is composed of PETase, lipase B (CALB), and mini cellulosome (mCbpA). First, the mode of reaction toward PET and bis(2-hydroxyethyl) terephthalate (BHET) by single enzymes confirmed that the PETase produced intermediate containing BHET and mono (2-hydroxyethyl terephthalate) (MHET), but CALB produced terephthalate (TPA). These results demonstrated that there are two enzymes available for sequential degradation. Second, the complex containing the carbohydrate binding module (CBM) showed 68% enhanced binding ability towards PET. Third, the enzymatic degradation of PET is a prolonged process. Afterwards, we observed long-term stability at 30℃ using BHET and confirmed the improvement in stability. Lastly, it was confirmed that the PET weight was decreased to 0.005g and 0.039mM of TPA was accumulated. This result showed approx. 4.5-fold of improvement compared to control. Taken together, this complex enhancing long-term enzymatic stability and binding affinity would be versatile to produce reusable TPA, upcycling, and reducing waste plastic in industry and environment.