粘性嗜热链球菌ST-1产胞外多糖发酵条件优化

Optim ization of fermentation conditions for exopolysaccharide production by ropy Streptococcus thermophilus ST-1

应用响应面法对一株粘性嗜热链球菌ST-1的产胞外多糖的发酵条件进行了优化。根据单因素的实验结果,选取接种量,发酵温度,发酵时间作为考察因素,以胞外多糖的产量作为响应值,利用Box-Behnken实验设计方法,建立了胞外多糖产量与三个考察因素之间的回归方程并得到最佳发酵条件为:接种量5%,发酵时间14 h,发酵温度42℃。验证试验结果表明,在此条件下得到的胞外多糖的产量为346.51 mg/L±1.05 mg/L,与方程预测值基本相符。

The optimization of fermentation conditions for ropy Streptococcus thermophilus ST-1 were investigated by response surface methodology in order to improve the yield of exopolysaccharide. The inoculum size, fermentation time and fermentation temperature were chosen as factors, and the yield of exopolysaccharide as response value based on onefactor test. The regression equation of EPS yield was established with three study factors using Box-Behnken methods. And the optimum fermentation conditions were obtained as the following： inoculum size 5 %, fermentation time 14 h and fermentation temperature 42 ℃. Validation experiment suggested that the yield of EPS could reached 346.51 mg/L ± 1.05 mg/L, similar to the forecast of regression equation.