Optimization of Polygalacturonase Production Condition for Bacillus licheniformis 3x05 Using Response Surface Methodology

Bacillus licheniformis 3x05, isolated from pepper retting water, was used for white pepper production. Response surface methodology was employed to optimize the fermentation condition of Bacillus licheniformis 3x05 for polygalacturonase production. In the first step, a 12-factor and 2-level Plackett-Burman design was conducted, and wheat bran concentration, initial pH and sodium chloride concentration were found to be the major factors. The 3 factors and ammonium sulfate concentration were selected as major factors for the next experimental design. In the next step, the path of the steepest ascent design was used to arrive in the vicinity of the optimum values for the major factors. The optimum fermentation condition was determined using Box-Behnken design and response surface analysis. The optimum fermentation broth contained wheat bran 11.0g/L, (NH4) 2SO4 2.50g/L, NaCl 5.78g/L, yeast extract 1 g/L, MgSO4 0.1g/L, FeSO4 0.002g/L, KCl 0.1g/L, NaNO3 2g/L, Tween 60 0.5mL/L, and initial pH 7.5 was adjusted. The broth was inoculated with 4% seed culture, and incubated at 33 degrees C and 160rpm for 48h. Under the optimum condition, polygalacturonase activity of 10.65U/mL was obtained.