Esterase fermentation in an external-loop airlift bioreactor and its application in D-lactic acid production

被引：0
|
作者：
Shen X.-L. [1 ]
Fan Y.-X. [2 ]
Wang Z. [1 ]
机构：
[1] College of Biological and Environmental Engineering, Zhejiang University of Technology
[2] College of Chemical Engineering and Materials Science, Zhejiang University of Technology
来源：
Zhejiang Daxue Xuebao(Gongxue Ban)/Journal of Zhejiang University (Engineering Science) | 2010年 / 44卷 / 02期
关键词：
D-lactic acid; Esterase; Ethyl lactate; External-loop airlift bioreactor; Fermentation; Immobilized cell; Optical resolution;
D O I：
10.3785/j.issn.1008-973X.2010.02.020
中图分类号：
学科分类号：
摘要：
The cells of Rhizopus sp. F-16 were immobilized by being entrapped into calcium alginate gels. The immobilized cells were cultivated in an external-loop airlift bioreactor (working volume 10 L and height-to-diameter ratio 2.9) for the production of esterase. The fermentation term of immobilized cells was shortened and the activity of esterase was improved compared with free cells. The optimum air flow rate and liquid volume for the fermentation of immobilized cells were 0.70 m3/h and 8.75 L, respectively. The esterase activity reached 41.6 U/g cell after 48 h fermentation. The suitable reaction pH value and the temperature of immobilized cells were 8.0~9.0 and 45~50 °C, respectively. The acidic and alkali stability and the thermal stability of immobilized cells were both enhanced than free cells. The immobilized cells can hydrolyze racemic ethyl lactate enantioselectively to produce D-lactic acid. When the substrate mass concentration was 150 g/L, the hydrolysis yield of ethyl lactate was 43.9% and the optical purity of D-lactic acid reached 95.7% after 3 h reaction. The immobilized cells were quite stable and can be repeatedly used for at least 6 batches of resolution reaction. The average hydrolysis yield of ethyl lactate was 43.3%, and the average optical purity of D-lactic acid was 95.4%.
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页码：320 / 325
页数：5
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