Using deep eutectic solvents to improve the biocatalytic reduction of 2-hydroxyacetophenone to (R)-1-phenyl-1,2-ethanediol by Kurthia gibsonii SC0312

Abstract

The effects of five deep eutectic solvents (DESs) on the production of (R)-1-phenyl-1,2-ethanediol from 2-hydroxyacetophenone catalyzed by Kurthia gibsonii SC0312 were investigated in this study. Of these, choline chloride/1,4-butanediol (ChCl/Bd) showed excellent biocompatibility and suitably increased the cell membrane permeability while having a little impact on the structure of DNA. Indeed, ChCl/Bd at the concentration of 2 % increased the catalytic rate of the cells by 22 %. The other DESs did not stimulate the catalytic capacity of the cells, despite some increases in the cell membrane permeability. Additionally, the conformation of DNA was visibly changed when adding the other examined DESs except for choline chloride/triethylene glycol. The DESs modified the fatty acid composition of cellular membrane, decreased the relative amount of iso-C14:0 and increased the relative amount of normal C15:0. Meanwhile, the DESs were able to improve the relative ratio of normal fatty acids to branched fatty acids. Finally, a highly efficient reduction of 80 mM 2-hydroxyacetophenone by K. gibsonii SC0312 in the ChCl/Bd-containing system was established, affording (R)-1-phenyl-1,2-ethanediol in 80 % yield and optical purity >99 % at 30 mg/mL wet cells. This work offers a promising approach for the preparation of (R)-1-phenyl-1,2-ethanediol from 2-hydroxyacetophenone using K. gibsonii SC0312.