Synergistic promotion for microbial asymmetric preparation of (R)-2-chloro-1-(2,4-dichlorophenyl)ethanol by NADES and cyclodextrin

Abstract

Microbial whole-cell catalysis has been a popular method for chiral alcohols preparation. In this study, Cyberlindnera saturnus ZJPH1807 was successfully employed as a biocatalyst to reduce 2-chloro-1-(2,4-dichlorophenyl)ethanone (CPE) to (R)-2-chloro-1-(2,4-dichlorophenyl)ethanol ((R)-CPEO), a key chiral intermediate of antifungal drug miconazole. In order to further improve the bioprocess yield, natural deep eutectic solvent and cyclodextrin were introduced into the reaction system as additives. It was found that carnitine/trehalose (C/Tre, 1:1 mol/mol) could increase the permeability of cell membrane appropriately and improve the mass transfer rate. And the addition of methyl-β-cyclodextrin (MCD) could improve the solubility of CPE in buffer solution, simultaneously promoting cofactor recycling. Furthermore, MCD and C/Tre exerted a synergistic effect on the acceleration of CPE bioreduction, producing 91.0% yield in 1.5 h at 35.8 mM CPE in a C/Tre-MCD-containing system, with a 12.4-fold increase in productivity compared to neat buffer solution only. When the substrate loading was increased to 67.1 mM, the yield could also achieve 84.2%. The established bioreduction process was also feasible at 100 mL preparation scale with a 88.5% (R)-CPEO yield. The integration of C/Tre and MCD can significantly improve catalytic efficiency for hydrophobic substrates and be applied in biocatalysis.