Asymmetric reduction of 2-octanone in water/organic solvent biphasic system with Baker's yeast FD-12

In the aqueous medium the asymmetric reduction of 2-octanone with Baker's yeast FD-12 was inhibited severely by the substrate and the product at higher concentrations, which resulted in a low yield and a low e.e. value of the object product (S)-2-octanol. Seven water/organic solvent biphasic systems were assayed in this work. FD-12 showed the best tolerance, catalytic activity and enantioselectivity in the water/n-dodecane system among the biphasic systems assayed. The metabolic activity retention (MAR) and viability of FD-12 in the n-dodecane containing system were 98% and 91.6%, respectively. The influence of the volume ratio Vaq/Vorg, temperature, pH value and the substrate concentration on the yield of 2-octanol and the e.e.(S) value was investigated. Under the optimum conditions (in the water/n-dodecane biphasic system, Vaq/Vorg 20/5, pH 8.0, 32 °C, 2-octanone concentration 500 mM), the final concentration of 2-octanol and the e.e.(S) value reached 105.60 mM and 89.38%, respectively, after 96 h reduction. The water/n-dodecane biphasic system with FD-12 was advantageous for the production of (S)-2-octanol of high final concentration and high e.e.(S) value.