A culture medium was optimized for the production of keratinolytic protease by a newly isolated strain of Bacillus licheniformis MZK-03 in shake-flask culture. Based on the results of preliminary experiments, feather mill, molasses and trace elements were found to be major variables in keratinolytic protease production. The concentrations of these ingredients were optimized by using two statistical approaches, namely Box-Wilson method and central composite design. The optimized culture medium, finally determined by using the statistical approaches, composed of 0.95% feather mill, 0.12% molasses and 1.44% trace elements. The keratinolytic protease production was increased by approximately 2-fold when the strain was grown in the optimized medium (95.2 U/ml) compared to the un-optimized medium (56.05 U/ml).
