Optimization of solid-state medium for the production of inulinase by Kluyveromyces S120 using response surface methodology

The optimization of nutrient levels for the production of inulinase by a newly strain Kluyveromyces S120 in solid-state fermentation (SSF) was carried out using response surface methodology (RSM) based on Plackett–Burman design and Box–Behnken design. In the first optimization step, a Plackett–Burman design was used to evaluate the influence of related factors. Inulin, corn steep liquor and (NH4)2SO4 were found to be more compatible supplement with the substrate of wheat bran and positively influenced on inulinase production. In the second step, the concentrations of the three nutrients above were further optimized using a Box–Behnken design. The final concentration of medium optimized with RSM was 12.72% inulin, 10.76% corn steep liquor and 1.61% (NH4)2SO4 by employing wheat bran as the solid substrate. The average inulinase activity (409.8 U/g initial dry substrate) in triplicate under optimal medium was obtained.