Wickerhamomyces subpelliculosus as whole-cell biocatalyst for stereoselective bioreduction of ketones

Newly isolated strains of Wickerhamomyces subpelliculosus were recognized as excellent whole-cell biocatalyst for bioreduction of various ketones. The biocatalytic properties of the new strains were demonstrated in this study by stereoselective bioreduction of acetophenone 1a, 2-heptanone 1b, phenylacetone 1c, 3,4-dimethoxyphenylacetone 1d and 1-cyclopropyl-2-(2-methoxy-4-nitrophenoxy)ethanone 1e. Our study is the first report on application of W. subpelliculosus as whole-cell biocatalyst for stereoselective bioreduction of prochiral ketones. In these processes, both the freshly harvested cell paste and the lyophilized cell powder were tested as biocatalyst using glucose or 2-propanol at various concentrations as cosubstrates for cofactor regeneration. The newly isolated strains of W. subpelliculosus showed diverse characteristics, including optimal pH, temperature and organic solvent tolerance. Bioreductions of phenylacetone 1c applying glucose as cosubstrate under various mild conditions resulted (S)-1-phenylpropanol [(S)-2c] in good to excellent conversion (c = 63.4%–99.9%) with excellent enantiomeric excess [ee_(S)-2c = 98.7%–99.8%].