Hydrophobic cell surface display system of PETase as a sustainable biocatalyst for PET degradation

Remarkably, a hydrolase from Ideonella sakaiensis 201-F6, termed PETase, exhibits great potential in polyethylene terephthalate (PET) waste management due to it can efficiently degrade PET under moderate conditions. However, its low yield and poor accessibility to bulky substrates hamper its further industrial application. Herein a multigene fusion strategy is introduced for constructing a hydrophobic cell surface display (HCSD) system in Escherichia coli as a robust, recyclable, and sustainable whole-cell catalyst. The truncated outer membrane hybrid protein FadL exposed the PETase and hydrophobic protein HFBII on the surface of E. coli with efficient PET accessibility and degradation performance. E. coli containing the HCSD system changed the surface tension of the bacterial solution, resulting in a smaller contact angle (83.9 +/- 2 degrees vs. 58.5 +/- 1 degrees) of the system on the PET surface, thus giving a better opportunity for PETase to interact with PET. Furthermore, pretreatment of PET with HCSD showed rougher surfaces with greater hydrophilicity (water contact angle of 68.4 +/- 1 degrees vs. 106.1 +/- 2 degrees) than the non-pretreated ones. Moreover, the HCSD system showed excellent sustainable degradation performance for PET bottles with a higher degradation rate than free PETase. The HCSD degradation system also had excellent stability, maintaining 73% of its initial activity after 7 days of incubation at 40 degrees C and retaining 70% activity after seven cycles. This study indicates that the HCSD system could be used as a novel catalyst for efficiently accelerating PET biodegradation.