| The carbonyl asymmetric reduction of-3-oxo-3-phenylpropionic acid ethyl ester to prepare (S)-3-hydroxy-3-phenylpropionate by Saccharomyces cerevisiae B5 was studied. The enantiometric excess of (S)-3-hydroxy-3-phenylpropionate can achieve 100%ee by reduction of Saccharomyces cerevisiae B5 cultivated by the liquid medium of intial pH 8.0 and preheated at 50℃for 30 min. The effects of bioconversion conditions on both yield and enantiomeric excess were evaluated. The reaction condition for the reduction of-3-oxo-3-phenylpropionic acid ethyl ester to prepare (S)-3-hydroxy-3-phenylpropionate were optimized, and the highest yield was achieved when the bioconversion was taken place at pH7.0 and 30℃for 24 h, the substrate concentration was 3.63 mmol/L and the biomass was 86 g/L(w/v). The experimental data showed that the best co substrate was glucose and the optimal glucose concentration was 10%. The yield and (S)-3-hydroxy-3-phenylpropionate enantiometric excess can achieve 98.4% and 100%ee, respectively. The high purity (S)-3-hydroxy-3-phenylpropionate was obtained by solvents extraction and silica column chromatography. The result showed that, the high purity (S)-3-hydroxy-3-phenylpropionate was attained from crude product by silica column chromatography with petroleum ether- ethyl acetate (7:1,V/V) as eluents, the sample volume was 4.8 mg/ml silicagel, the ratio of column's diameter to height was 1:12, and the eluant velocity was 1.5 ml/min.The kinetic model of asymmetric reduction of-3-oxo-3-phenylpropion ic acid ethyl ester using Saccharomyces cerevisiae B5 was established. The effect factors on reduction, the type and the content of co substrate and coenzyme, and the changes of the substrate and product content vs. time during the reaction process were investigated. The results indicate that NADPH is reducer. The reduction process conforms with sequence mechanisms. The model parameters are as follows: vm=5.0×10-4 mol·L-1·h-1, k1=1.5×10-6 mol·L-1·h-1, k2=3.0×10-3mol·L-1·h-1. The kinetic model is in good agreement with the experimental data.(S)-3-hydroxy-3-phenylpropionate was prepared continuously by coupling of microbial transformation and membrane separation. The influence factors of membrane flux, and the influence of operating conditions on reactor capacity and reaction conversion were investigated. The kinetic model of continuous operating process was established. The appropriate molecular weight cut off of the ultrafiltration membrane is 30 KDa. The reactor capacity can reach a maximum of 0.136 h 1 under a condition of 86 g/L biomass and 20 ml/min membrane flux. After reacting for 7 d, 3.68 mmol?L 1?d 1 product was obtained from 18.29 mmol substrte, while the conversion of bacth reaction was almost zero. It was illustrated that continuous operation can relieve inhibition of high concentration substrate to the reaction. The model parameters obtained through fitting with experimental datas are as follows: vm=3.0×10-3mol·L-1·h-1,kcat=3.5×10-4mol·L-1·h-1,k1=3.1×10-2mol·L-1,k2=5.0×10-7mol·L-1. The kinetic model is in good agreement with the experimental data.
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