Optimization of medium composition for keratinase production on feather by Bacillus licheniformis RG1 using statistical methods involving response surface methodology

A 3.5-fold increase in keratinase production by Bacillus licheniformis RGl was achieved by using statistical methods involving Plackett-Burman design and response surface methodology. Eight variables were screened using Plackett-Burman design. Of these, glucose, peptone and glutathione were found to affect the response signal positively, whereas CaCl2 had a negative effect. Further interaction of these factors, along with phosphate and incubation time, was studied using response surface methodology. An optimum keratinase production of 1295 units/mg dry weight was obtained with the following medium composition: 1 % glucose, 1 % peptone, 1 % phosphate, 0.05 % glutathione, 0.5 % feather and 2 % inoculum under shaking at 250 rev./min with an incubation period of 72 h at 37degreesC. Keratinase production was found to be a function of biomass and maximum production occurred during the stationary phase.