灰树花发酵产β-葡萄糖苷酶和胞内多糖培养基及条件优化

Optimization of Medium Composition and Submerged Culture Conditions for Production of β-glucosidase and Intracellular Polysaccharide by Grifolafrondosa

对灰树花液体深层发酵产β-葡萄糖苷酶和胞内多糖的培养基组成和发酵条件进行优化。通过单因素试验确定最佳碳源为葡萄糖,最佳氮源为麸皮。采用响应面中心组合试验设计,同时建立产酶活力和胞内多糖随葡萄糖和麸皮含量变化的二次回归方程,得到灰树花发酵最优培养基组成(g/L):葡萄糖27.83,麸皮35.57,KH_2PO_43,MgSO_4 1.5,VB_1 0.05,在此条件下生物量、胞内多糖含量及β-葡萄糖苷酶活力分别达到1.397 g/100m L,2.176 g/L和22.177 U/100 mL,比优化前分别提高1.9,0.75倍和2.71倍。研究灰树花液体发酵培养过程中初始pH、接种量、温度、转速、接种种龄和发酵时间等发酵条件对产酶活力和胞内多糖产量的影响,结果表明,灰树花发酵的最适初始pH为5.0,接种量10%,选取培养7 d的种子液,25℃,180 r/min振荡培养7 d即可结束发酵。

Optimization of medium composition and submerged culture conditions for β-glucosidase and intracellular polysaccharide （IPS） production by Grifolafrondosa was studied. Glucose and bran were the most suitable carbon and nitrogen sources determined by single factor experiment. Afterwards, response surface methodology was used to achieve the favorable medium composition, and a quadratic regression equation for the change of enzyme activity and IPS with glu cose and bran was established. The result was glucose 27.83 g/L, bran 35.57 g/L, KH2PO4 3 g/L, MgSO4 1.5 g/L, VB1 0.05 g/L while biomass, IPS and β-glucosidase can be obtained respectively at 1.397 g/100mL, 2.176 g/L, 22.177 U/100 mL, which is 1.9, 0.75, 2.71 timesas much before optimization. The effect of submerged culture conditions including pH, inoculation, temperature and fermentative time on enzyme activity and IPS was investigated subsequently. The result shows the optimal pH and inoculation for both fl-glucosidase and IPS production in shake flask cultures were 5 and 10%. In addition, the submerged culture of Grifolafrondosa can be finished at 7 dayswben choose the liquid seed cul- tured for 7 days and the temperature and rotation speed were set at 25℃ and 180r/min, respectively.