Abstract:

Plackett-Burman method was adopted to screen main factors from 16 ones affecting Lactobacillus acidophilus extracellular polysaccharide yield. Based on a Box-Behnken central composite design involving 15 experiments of 3 variables at 3 levels, the interactive effects among the factors were analyzed by response surface methodology. Results showed that the most significant effects on the fermentation process due to concentrations of Tween 80, potassium dihydrogen phosphate and citric acid triamine in medium were observed; the optimal values of their concentrations were determined as follows: Tween 80 0.5 ml/L, potassium dihydrogen phosphate 3.95 g/L, citric acid triamine 4.2 g/L; a maximum extracellular polysaccharide yielof 3.99 g/L was achieved at these optimal concentration levels.

Key words: Lactobacillus acidophilus extracellular polysaccharide, response surface methodology, Tween 80, potassium dihydrogen phosphate, citric acid triamine