Enhanced biodegradation of waste poly(ethylene terephthalate) using a reinforced plastic degrading enzyme complex

• Published in: The Science of the total environment 2022-10, Vol.842, p.156890-156890, Article 156890
• Main Authors: Hwang, Dong-Hyeok, Lee, Myeong-Eun, Cho, Byeong-Hyeon, Oh, Jun Won, You, Seung Kyou, Ko, Young Jin, Hyeon, Jeong Eun, Han, Sung Ok
• Format: Article
• Language: English
• Subjects: Binding affinity; Carboxylic ester hydrolases complex; Enzyme stability; Sequential degradation; Waste poly (ethylene terephthalate)
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2022.156890

Poly(ethylene terephthalate) (PET) is synthesized via a rich ester bond between terephthalate (TPA) and ethylene glycol (EG). Because of this, PET degradation takes a long time and PET accumulates in the environment. Many studies have been conducted to improve PET degrading enzyme to increase the efficiency of PET depolymerization. However, enzymatic PET decomposition is still restricted, making upcycling and recycling difficult. Here, we report a novel PET degrading complex composed of Ideonella sakaiensis PETase and Candida antarctica lipase B (CALB) that improves degradability, binding ability and enzyme stability. The reaction mechanism of chimeric PETase (cPETase) and chimeric CALB (cCALB) was confirmed by PET and bis (2-hydroxyethyl terephthalate) (BHET). cPETase generated BHET and mono (2-hydroxyethyl terephthalate (MHET) and cCALB produced terephthalate (TPA). Carbohydrate binding module 3 (CBM3) in the scaffolding protein greatly improved PET film binding affinity. Finally, the final enzyme complex demonstrated a 6.5-fold and 8.0-fold increase in the efficiency of hydrolysis from PET with either high crystalline or waste to TPA than single enzymes, respectively. This complex could effectively break down waste PET while maintaining enzyme stability and would be applied for biological upcycling of TPA. [Display omitted] •The novel poly (ethylene terephthalate) (PET) hydrolytic complex was developed for waste PET degradation.•PET degradation complexes were better binding ability with PET than free enzymes.•This complex retained enzyme activity and stability during PET depolymerization.•The combined complex could degrade high crystalline PET and waste PET.