Stereoselective Bioreduction of Acetophenone to (R)-1-Phenylethanol by Bacillus thuringiensis

Optically pure alcohols have a pivotal synthetic role, being key intermediates for numerous pharmaceutical agents. Therefore, the synthesis of optically pure alcohols is now becoming a foremost research field in both academia and industries. Herein, Bacillus thuringiensis has been described for the first time for the bioreduction of acetophenone to 1-phenylethanol. Five incubated bacillus species and a consortium were investigated for the reduction of acetophenone. Among them, Bacillus thuringiensis (growing cells) exhibited >99% conversion efficiency of acetophenone (40 mM). The biocatalyst produced (R)-1-phenyl ethanol with excellent stereoselection (99%) at pH 7.5 after 24 h reaction intervals. To enhance the solubility of substrate and cofactor regeneration, isopropanol (10% v/v) was found to be effective among different tested cosolvents. The biocatalyst displayed excellent stereoselectivity and provided R-enantiomer with 99% enantiomeric excess.