【作者】 张静娟；

【导师】 徐学明；

【作者基本信息】 江南大学 ， 动物营养与饲料科学， 2007， 硕士

【摘要】 本论文以法夫酵母(Xanthophyllomyces dendrorhous)为出发菌株发酵生产新科斯糖(neokestose),主要研究内容包括:摇瓶发酵优化新科斯糖的生产方法和基本培养条件;补料发酵优化生产新科斯糖的发酵工艺;新科斯糖的部分生理功能的研究。以法夫酵母269为出发菌株,进行了对摇瓶发酵条件优化的一系列单因素试验以及正交试验,确定最佳发酵条件:蔗糖110g/L,尿素9g/L,pH6.5(磷酸氢二钠-柠檬酸缓冲体系),接种量6g/L,18℃,24h。在此条件下发酵得的新科斯糖含量为70.9g/L,蔗糖转化率为0.644。比优化前发酵效率提高了84.1%。接种指数期酵母菌体比稳定期的酵母菌体能获得更高的新科斯糖产量,但差异并不显著。细胞的循环利用虽然可以减少菌体的浪费,但是随着循环次数的增多,新科斯糖的产量受到抑制。通过研究不同通气量,不同补料方式,不同补料时间浓度对发酵的影响,确定补料发酵可以提高发酵效率和新科斯糖的产率。10L发酵罐中,在通气量为8L/min,pH为6.5±0.5的条件下,初始装4L培养基,发酵24h后一次性补以3倍浓度的蔗糖溶液,再经24h发酵得新科斯糖浓度为119.3g/L,蔗糖的转化率达0.662。新科斯糖对大肠杆菌和双歧杆菌体外生长影响试验表明。与对照组葡萄糖和普通低聚果糖比较,大肠杆菌在新科斯糖上的生长相对弱一些,但差异并不显著,而双歧杆菌能很好的利用新科斯糖在体外生长,是利用普通低聚果糖增殖效果的1.4倍,葡萄糖的2倍。更多还原

【Abstract】 Fructooligosaccharides (FOS) of the 1F type have been most extensively investigated as prebiotic compounds. The production of 6F type oligosaccharides from sucrose has also received some attention but so far production of potential prebiotic oligosaccharides of the 6G series,such as the trisaccharide neokestose, has not been investigated.In this work,the production of neokestose by was investigated, the main contents include : the optimization of shake flask culture conditions of neokestose production ;the optimization of fed-batch culture conditions of neokestose production; studies on the physiological function of neokestose.Neokestose accumulated as the main product in the culture broth of Xanthophyllomyces dendrorhous (Phaffia rhodozyma) growing on sucrose. The results suggest that neokstose is composed of 2-linked and 1,2-linked fructose and 1,6-linked glucose.It’s a novel syrup fructooligosaccharide.A series of single-factor test and orthogonal test were carried on to determine the optimum shake flask culture conditions of neokestose production by Xanthophyllomyces dendrorhous 269 : sucrose 110g/L, urea 9g/L, pH 6.5, cell concentration 6g/L,18℃, 24h. Under this condition, the concentration of noekestose could reach 70.9g/L, sucrose conversion ratio reached 0.644. It is increased 1.84 fold,compared with the neokestose growing under YM medium.Cells harvested in the exponential growth phase produced neokestose more efficiently than stationary phase cells,but the diffierence is not significant.Recycling of cells reduced the level of neokestose production.Fed-bacth fermentation was useful for the level of neokestose production.Different ventilation r and different feeding modes were studied.In 10L fermenter, with initial installation of 4L medium ventilation 8L/min, pH 6.5±0.5, a one-stage fed bacth culture was performed after fermented for 24 hours.The final neokestose concentration reached 119.3g/L , sucrose conversion ratio reached 0.662.The effect of neokstose on Escherichia coli and Bifidobacterium in vitro were investigated. Less biomass was produced by E.coli from glucose, FOS as carbon source and than from neokestose, but were not significantly different. And more biomass was produced by the bifidobacteria from glucose, FOS than from neokestose. Bifidobacteria utilized the neokestose to a greater extent,1.4 times than FOS and 2 times than glucose.更多还原