Cultivation of Pichia capsulata as a whole-cell biocatalyst with NADH-dependent alcohol dehydrogenase activity for R-1-phenylethanol production

• Cultivation process for the production of alcohol dehydrogenase was developed.
• NADH-dependent enzyme from P. capsulata converted acetophenone to R-1-phenylethanol.
• Optimal conditions for the production of whole-cell biocatalyst were found.

The aim of this work was to develop a cultivation process for the production of NADH-dependent alcohol dehydrogenase catalyzing a less common reduction of acetophenone to R-1-phenylethanol, an important compound for fragrance and flavor industry. Screening of 23 yeast strains showed that Pichia capsulata ATCC 16753 cells possess high catalytic activity for acetophenone reduction to R-1-phenylethanol. This high alcohol dehydrogenase activity was observed not only for whole cells but also for a raw enzyme solution using NADH as the cofactor. R-1-phenylethanol was produced in enantiomeric excess values of over 99% for the raw enzyme solution and of over 90% for the whole-cell biocatalyst cultivated at optimal conditions. The key factors for achieving high yield and selectivity were: proper cultivation time, glucose concentration and dissolved oxygen control.