Asymmetric reduction of substituted acetophenones using once immobilized Rhodotorula glutinis cells

The asymmetric reductions of acetophenone and its analogues using once immobilized Rhodotorula glutinis cells were studied. The performance and reaction parameters of the immobilized cells were also investigated and it was determined that the cells could be used 15 times in batch processes. All chiral alcohols obtained using purification procedures were of sufficient enantiopurity (>99%) of the (S)-enantiomer. The applicability of the optimized process for a preparative scale bioreduction was shown. Under the optimum conditions, 35 mM (4.3 g) of the product ((S)-1-phenylethanol) was produced from 45 mM (5.4 g) of the substrate (acetophenone) with one time immobilized R. glutinis EBK-2 cells (6 g wet weight). The yield was calculated as 77%. In this study, it was found that the buffer level had a very significant effect on the reaction activity. Our results demonstrate that the optimized process can be implemented on a preparative scale.