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 RG1 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 37 (degree)C. Keratinase production was found to be a function of biomass and maximum production occurred during the stationary phase.