Production of Escherichia coli phytase by recombinant Pichia pastoris

• Main Authors: Pei-Hua Wu, 吳佩樺
• Other Authors: Ching-Tsan Huang
• Format: Others
• Language: zh-TW
• Published: 2000
• Online Access: http://ndltd.ncl.edu.tw/handle/38609423050340225335

碩士 === 國立臺灣大學 === 農業化學研究所 === 88 === Phytase, a valued feed additive for monogastric animals, has been used to hydrolyze phytic acid in feeds and to reduce the antinutrient ability of phytic acid. It also helps the release of phosphorous from phytic acid to increase phosphorous digestibility. In this study, the production of Escherichia coli phytase in recombinant Pichia pastoris KM 71-61 was investigated and the biochemical characteristics of said phytase were presented. By adding 0.5% methanol every 24 h during the stationary phase in the flask cultures, the phytase activity reached up to 150 U/ml after 144 h of induction. The phytase activity increased one fold in the case of replacing culture with fresh medium before induction. With the same strategy, the phytase activity is about 600 U/ml in fermentor cultures after 168 h of induction. The increase of phytase activity is not resulted from adding extra nutrients but from removing inhibitors. The phytase activity on cellular base was higher when initiated with lower cell density. The starvation before induction has little effect on the phytase activity due to the slow utilization of methanol in Pichia pastoris KM 71- 61.