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Jer-Yiing Houng,Jui-Ching Tseng,Hsia-Fen Hsu,Jiumn-Yih Wu 한국화학공학회 2008 Korean Journal of Chemical Engineering Vol.25 No.6
This study investigated the kinetic characteristics of asymmetric bioreduction of ethyl 4-chloro acetoacetate (ECA) to produce (S)-4-chloro-3-hydroxybutyric acid ethyl ester (S-CHBE) by baker’s yeast in a water-organic solvent biphasic system. Exactly how several organic solvents affect reaction performance was studied first. Among the solvents tested, petroleum ether exhibited the optimum reaction efficiency. Compared with the aqueous system, reaction yield was enhanced from 74.5% to 84.0%, and the product’s ee increased from 82.3% to 88.0% after 10% petroleum ether was added. The kinetic behavior of asymmetric bioreduction of ECA in the petroleum ether-water biphasic system was then examined by using a mathematical model. Kinetic analysis reveals that the maximal reaction rate and affinity between the substrate and the biocatalyst were both lower in the biphasic system than in the aqueous system. Additionally, the substrate inhibition effect was greater in this biphasic system than in the aqueous system. However, the ratio of the formation rate for producing S-CHBE to that for producing R-CHBE in the biphasic system was significantly higher than that in the aqueous system. Moreover, adding petroleum ether reduced spontaneous ECA degradation markedly. These two kinetic characteristics explain why the biphasic system exhibited a higher yield and a better product’s ee (enantiomeric excess) than the aqueous system.
Chin-Fa Hwang,Jen-Han Chang,Jer-Yiing Houng,Cheng-Chih Tsai,Chien-Ku Lin,Hau-Yang Tsen 한국생물공학회 2012 Biotechnology and Bioprocess Engineering Vol.17 No.4
An immune-enhancing strain, Lactobacillus plantarum Pi06, isolated from a healthy infant was used for biomass production following optimization of the medium in shake-flask culture. Preliminary studies showed that commercial MRS medium and cultivation under static conditions generated higher biomass production than four other tested media with or without a shaking condition. The selected medium composition, consisting of glucose,yeast extract, soy peptone, ammonium citrate, and corn steep liquor, was further optimized using a systematic method that integrated the Taguchi array design and the Box–Behnken method. The response effects of these factors were first investigated using Taguchi design under an L16 (45) array. The suggested medium composition,derived from Statistica 7.1 using the Taguchi design, was applied to cultivate cells and a biomass of 7.16 g dry cell weight (DCW)/L was obtained. Response surface methodology based on the Box–Behnken method for the three response variables of glucose, yeast extract, and corn steep liquor was then used to further increase the biomass level to 8.94 g DCW/L. The resulting optimum medium consisted of 35 g/L glucose, 35 g/L yeast extract, and 40 mL/L corn steep liquor. Compared with the initial medium, the biomass yield was improved from 4.31 to 8.94 g DCW/L, an enhancement of approximately 107%.