Improved (<Emphasis Type="Italic">R</Emphasis>)-phenylacetylcarbinol production with <Emphasis Type="Italic">Candida utilis</Emphasis> pyruvate decarboxylase at decreased organic to aqueous phase volume ratios

The effect of decreasing the organic (octanol) to aqueous phase volume ratio was evaluated in a two-phase enzymatic process for (R)-phenylacetylcarbinol (PAC) production. Decreasing the ratio from 1:1 to 0.43:1 at 4°C increased PAC in the organic phase from 112 g/l to 183 g/l with a 10% improvement in overall productivity. Interestingly, the rate of enzyme (pyruvate decarboxylase) activity loss was unaffected by the reduced phase ratio over the reaction period (48 h). At 20°C and 0.43:1 phase ratio the organic phase PAC concentration increased to 212 g/l and the overall productivity increased by 30% although the PAC yield (based on pyruvate) declined by about 10% due to greater byproduct acetoin formation at the higher temperature. Product recovery in such a system is facilitated both by the higher PAC concentration and the reduced organic phase volume.