Optimization of Inulinase Fermentation Conditions of Aspergillus Niger X-6 Using Respose Surface Methodology

Inulinase is a hydrolase used for inulin hydrolysis to produce functional fructooligosaccharides and fructose. The objective of the research was to obtain the optimum fermentation conditions of inulinase from Aspergillus niger X-6 mutated by microwave treatment with the Plackett-Burmen design and response surface methodology. The content of wheat bran, inulin, peptone, yeast extract, fermentation time, temperature, pH, and inoculum affecting the fermentation were evaluated. The content of wheat bran, fermentation time and pH were significant parameters on the fermentation conditions as evaluated through variance analysis of Plackett-Burman. The fermentation conditions were further explored with Box-Behnken experimental design. The enzyme activity of the Aspergillus niger X-6 reached 20.42 U · mL^-1 at a optimum conditions of the content of wheat bran 4.64%, fermentation time 81.5 h, pH 6.0, increased 30.81% compared to the result of optimization before.