Production of Ethyl (S)-(-)-4-Chloro-3-hydroxybutyrate by Asymmetrical Reduction of Ethyl 4-Chloroacetoacetate with Aureobasidium pullulans SW0202

Aureobasidium pullulans SW0202 with high enantioselectivity for asymmetric reduction of ethyl 4-chloroacetoacetate(COBE) to ethyl (S)-4-chloro-3-hydroxybutyrate (S-CHBE) was isolated. The asymmetric reduction of COBE to optically active CHBEcatalyzed by Aureobasidium pullulans SW0202 in aqueous phase was also investigated. The reduction was conducted inK2HPO4-KH2PO4 buffer, and the concentrations of COBE and CHBE as well as optical purity of the product were determined bycapillary gas chromatography (GC) and chiral capillary GC respectively. The results showed that the optimal conditions for theconversion were the initial cell concentration 0.32 g/mL(wet weight), the initial COBE concentration 20 g/L, pH 7.0 and the temperature30℃. The molar conversion rate reached 79.6% (20.32 g/L CHBE), with 97.8% e.e. Subsequently the experimental results of batchsupplement of substrate indicate that this strategy can greatly reduce substance inhibition.