PRODUCTION OF 6G-FRUCTOSYLTRANSFERASE BY SUBMERGED CULTURE OF XANTHOPHYLLOMYCES DENDRORHOUS

• Main Authors: Chao-Kai Wang, 王炤凱
• Other Authors: Dey-Chyi Sheu
• Format: Others
• Language: zh-TW
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/08961278476923748458

碩士 === 大同大學 === 生物工程學系(所) === 101 === Neofructooligosaccharides (neoFOS), one of the prebiotics, can be produced by the catalytic reaction of 6G-fructosyltransferase on sucrose. In this work, production of intracellular 6G-fructosyltransferase by submerged culture of Xanthophyllomyces dendrorhous BCRC 22500 was investigated. The fermentation was performed in a 5-L fermenter with a working volume of 3 L at 20oC, 300 rpm and 2 vvm. Other fermentation conditions were varied and the biomass and enzyme activity were compared. The fermentation medium consisted mainly of yeast extract and sucrose. During the fermentation the pH of culture broth decreased due to the production of organic acid, therefore the pH was controlled by automatic addition of 2 N NaOH. When the fermentation was carried out at different pH, an optimal pH at 7.0 was obtained. Generally at low concentration, biomass and enzyme activity increased with the increase of yeast extract or sucrose. Initial concentration of sucrose at 10% was better than at 5%. However, yeast extract of 3% was better than of 4%. Zinc ion has negative effect whereas magnesium ion has positive effect. When the culture medium was composed of 3% yeast extract and 10% sucrose, after fermentation for 24 h 6G-fructosyltransferase activity at 17.6 U/mL (fresh cell 58.9 g/L) was achieved. Furthermore, in order to reduce the cost of culture medium, the expensive yeast extract was replaced by an alkaline hydrolysate of yeast powder. 6G-fructosyltransferase activity at 15.9 U/mL (fresh cell 53.3 g/L) was obtained when the fermentation medium was composed of 10% sucrose, 0.3% magnesium sulfate and an alkaline hydrolysate of 3% yeast powder.