Complete decomposition of poly(ethylene terephthalate) by crude PET hydrolytic enzyme produced in Pichia pastoris

Using enzymes to decompose poly(ethylene terephthalate) (PET) is an attractive strategy to the sustainable utilization of PET, and an effective production platform of PET degrading enzyme is a prerequisite to achieve this goal. Here, we exploited the industrial yeast strain Pichia pastoris to produce a potent PET hydrolase termed FAST-PETase, whose performance was further elevated by removing two N-linked glycosylations through molecular engineering. The expression of the yielded variant, FAST-PETase-212/277, was elevated by antibiotics selection and chaperon co-expression to exceed 3 g/L in a 30-L fermenter. Notably, the crude fermentation product can be directly applied to decompose PET without purification. More than 95 % postconsumer PET can be achieved by 0.5 mgenzyme gPET-1 in 24 h in a 10-L reaction system in a reactor. These results demonstrate the economic viability of producing PET hydrolytic enzyme with modern fermentation facilities for large scale PET decomposition.