Surface display of (R)-carbonyl reductase on Escherichia coli as biocatalyst for recycling biotransformation of 2-hydroxyacetophenone

Abstract

The purified (R)-Carbonyl reductase (RCR) is widely applied in the synthesis of chiral compounds, but often involves tedious procedures and high production costs of protein separation and purification. A surface immobilization of biocatalyst on cell surface for biotransformation is an option for ease enzyme separation and recycling. In this study, the RCR from Candida parapsilosis was immobilized on the surface of E. coli using the Lpp–OmpA and EhaA anchors, showing that the Lpp–OmpA is better for displaying the target molecules in terms of enzyme activities, product formation, and display efficiency. By deleting the NAD+ degrading enzyme UshA, the whole-cell biocatalytic activity was two-fold higher than that of the original strain. The created biocatalyst can retain about 80% of its catalytic activity after four rounds of recycling, reached the conversion rate of 83.5% within 30 mins with the substrate (R)-PED concentration of 1 mM. This study provides a novel strategy for 2-hydroxy acetophenone synthesis using the surface display of the enzyme on the cell while avoiding enzyme purification and side reactions from the host.