Cell Surface Display of Poly(3-hydroxybutyrate) Depolymerase and its Application

We have expressed extracellular poly(3-hydroxybutyrate) (PHB) depolymerase of Ralstonia pickettii T1 on the Escherichia coli surface using Pseudomonas OprF protein as a fusion partner by C-terminal deletion-fusion strategy. Surface display of depolymerase was confirmed by flow cytometry, immunofluorescence microscopy and whole cell hydrolase activity. For the application, depolymerase was used as an immobilized catalyst of enantioselective hydrolysis reaction for the first time. After 48 h, (R)-methyl mandelate was completely hydrolyzed, and (S)-mandelic acid was produced with over 99% enantiomeric excess. Our findings suggest that surface displayed depolymerase on E. coli can be used as an enantioselective biocatalyst.