Optimization of medium components for an endoinulinase strain by response surface methodology

The strain with high endoinulinase productivity was screened, named G-60 which was collected from the root soil of Jerusalem artichoke in Shihezi city of Xinjiang province.A Plackett-Burman design was used to evaluate the influence of eight factors.The results showed that inulin added amount, content of the peptone and the liquid medium volume played an important role in influencing the endoinulinase activity.Then the path of steepest ascent and the central composite design were suitable for further optimization, the optimal concentration of the variables were determined as: Inulin 66.5g /L, Peptone 29.1g /L, and liquid medium volume 49.38mL.Under this condition, the endoinulinase activity was increased to 24.62U /mL, which was improved by 1.55 times than before optimization.