Improving Pseudomonas sp. esterase performance by engineering approaches for kinetic resolution of 2-acetoxyphenylacetic acids

Abstract

The catalytic performance of Pseudomonas sp. ECU1011 esterase (PsE) in the kinetic resolution of ( R, S)-2-acetoxyphenylacetic acid (APA) was significantly improved by substrate modification, biocatalyst permeabilization and immobilization. The reaction system was modified, and the sodium salt of the substrate (APA Na), instead of APA, was hydrolyzed in aqueous phase without buffer. Considering the improved substrate solubility and the decreased biocatalyst inactivation, the reaction rate increased 3.7-folds and the spontaneous hydrolysis of the substrate reduced by 48%. During the cell permeabilization, the hydrolytic activity of the whole-cell biocatalyst was increased by 2.3-fold after 2 h of pretreatment with 10% (v/v) toluene. The permeabilized cells were further entrapped in calcium alginate, resulting in 171% activity recovery with a half-life of 123 h at 30 °C. Using the modified reaction system with high reaction rates and the modified biocatalyst with high activity and stability, this biocatalytic process can be transformed into a practical and environmentally friendly bioprocess for the efficient production of ( S)-mandelic acid and ( S)- o-chloromandelic acid.