Monday, July 30, 2007
P40

Study of fermentation strategies for enhancing expression of rumen phytase (phyA-7) in recombinant Escherichia coli

John Chi-Wei Lan1, Chun-Chieh Cheng2, Hui-Lin Lai2, Fu-Hwa Liu2, and Kao-Jan Cheng2. (1) Biorefinery & Bioprocess Engineering Laboratory, Department of Chemical Engineering and Materials Science, Yuan-Ze University, 135 Yuan-Tung Road, Chung-Li, Taoyuan, 32003, Taiwan, (2) Agricultural Biotechnology Research Center, Academia Sinica, Taiwan

Abstract:
Phytase (myo-inositol hexakisphosphae phosphohydrolase, EC 3.1.3.8) dedicated capable to catalyse the release of phosphate from phytate (myco-inositol hexakiphosphate) has been applied as an industrial feed enzyme to consequently control the agricultural pollutions that significantly limits phosphorus generated from monogastric animals. A gene encoding mutant phytase (phyA-7) from products of error-prone polymer chain reaction (PCR) was cloned in recombinant Escherichia coli. The comparisons of various fermentation strategies at laboratory fermentation scale were investigated and discussed. The results demonstrated that the level of phytase activity was improved from 76 to 269 U ml-1 for the flask culture and from 684 to 3120 U ml-1 for 5 litres of high cell-density fermentation, respectively. It showed that two-stages of fermentation strategy could diminish the influence of metabolic intermediates which may present as an inhibitor upon enzyme expression.

Key words: rumen phytase; phytate; polymer chain reaction; gene expression; fermentation


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