Optimization of the asymmetric synthesis of (S)-1-phenylethanol using Ispir bean as whole-cell biocatalyst

Abstract

Abstract In this study, enantiomerically pure (S)-1-phenylethanol was produced via asymmetric bioreduction of acetophenone. Ispir bean (Phaseolus vulgaris) was used as an alcohol dehydrogenase (ADH) source since whole cells are cheaper than isolated enzymes. Acetone powder methodology was applied for biocatalyst. Glucose was used as a cosubstrate in-order to regenerate cofactor (NADPH). The reactions were carried out in an orbital shaker whose temperature and agitation rate can be controlled. (S)-1-phenylethanol concentration was analyzed by HPLC using a Chiralcel OB column. Effects of the reaction time, substrate concentration, cosubstrate concentration and biocatalyst concentration on the (S)-1-phenylethanol production were investigated using Response Surface Methodology (RSM). 36 h bioreduction time, 6 mM acetophenone concentration, 25.15 mM glucose concentration, and 175 mg/mL biocatalyst concentration were determined as optimum values. In these conditions, 2.4 mM (S)-1-phenylethanol was obtained in phosphate buffer (pH=7.0) at 30°C with >99% enantiomeric excess.