Optimum Conditions for the Production of Keratinase by Bacillus sp. KN-517 and Application to the Degradation of Hair

Abstract A microbial strain having high keratinase activity was isolated from the soil of poultry factories of Gyeonggi or Chungcheong-do. The isolated strain was identified as Bacillus sp. based on its morphological and biochemical characteristics. In this study, the optimal conditions for the production of keratinase by this strain were investigated. The optimal medium composition for the keratinase production was determined to be 3.5 % chicken feather as carbon source, 1.0 % tryptone as organic nitrogen source, 1.0 % KNO3 as inorganic nitrogen source and 0.05% KCl, 0.05 % KH2PO4, 0.03 % K2HPO4 as mineral source and 0.01 % yeast extract as growth factor. The optimal temperature and pH was 40 ℃ and 8.5 with shaking culture (200 rpm), respectively. The maximum keratinase production reached to 123 units/ml after 42 hr of cultivation under the optimal condition. When the hair was used as the sole carbon source, the maximum enzyme activity was 88 units/ml after 120 hr and in this case, the hair added in the medium was not degraded completely but got thinner than the control by 20%