Asymmetric reduction of prochiral aromatic ketones by a Lactobacillus paracasei strain

In recent years enantiomerically pure compounds have attracted great attention industrially. Enantiomerically pure chiral alcohols are important building blocks in various fields of industry. Because of the increasing interest in chiral compounds the studies on producing enantiomerically pure chiral compounds with bioreduction reactions have gained importance. In this study, enantiomerically pure 1-phenyl ethanol, a precursor of many pharmacological products, was produced via bioreduction of acetophenone. Seven strains of Lactobacillus paracasei were evaluated as biocatalyst in the asymmetric reduction of acetophenone to (R) or (S)-1-phenyl ethanol. Among these lactic acid bacteria (LAB) strains Lactobacillus paracasei BD87E6 was determined to be a biocatalyst that has the most efficient asymmetric reduction ability for the enantioselective reduction of acetophenone. Under the optimized reaction conditions, aromatic prochiral ketones were converted to the corresponding chiral secondary alcohols with the result of reaching up to 98% enantiomeric excess. This method enables for a promising and alternative approach to the synthesis of biologically important seconder alcohols by using an environmentally friendly and a light method.