Synergistic biodegradation of poly(ethylene terephthalate) using Microbacterium oleivorans and Thermobifida fusca cutinase.

Abstract

Poly(ethylene terephthalate) (PET) is a major source of plastic pollution. Biodegradation technologies are of paramount interest in reducing or recycling PET waste. In particular, a synergistic microbe-enzyme treatment may prove to be a promising approach. In this study, a synergistic system composed of Microbacterium oleivorans JWG-G2 and Thermobifida fusca cutinase (referred to as TfC) was employed to degrade bis(hydroxyethyl) terephthalate (BHET) oligomers and a high crystalline PET film. A novel degradation product that was obtained by M. oleivorans JWG-G2 treatment alone was identified as ethylene glycol terephthalate (EGT). With the addition of TfC as a second biocatalyst, the highest synergy degrees for BHET oligomers and PET film degradation were 2.79 and 2.26, respectively. The largest amounts of terephthalic acid (TPA) and mono(2-hydroxyethyl) terephthalate (MHET) (47 nM and 330 nM, respectively) were detected after combined treatment of PET film with M. oleivorans JWG-G2 at 5 × 103 μL/cm2 and TfC at 120 μg/cm2, and the degree of PET film surface destruction was more significant than those produced by each treatment alone. The presence of extracellular PET hydrolases in M. oleivorans JWG-G2, including three carboxylesterases, an esterase and a lipase, was predicted by whole genome sequencing analysis, and a predicted PET degradation pathway was proposed for the synergistic microbe-enzyme treatment. The results indicated that synergistic microbe-enzyme treatment may serve as a potentially promising tool for the future development of effective PET degradation. KEY POINTS: • An ecofriendly synergistic microbe-enzyme PET degradation system operating at room temperature was first introduced for degrading PET. • A novel product (EGT) was first identified during PET degradation. • Potential PET hydrolases in M. oleivorans JWG-G2 were predicted by whole genome sequencing analysis.