Feather-degrading Bacillus species from poultry waste

Feather-degrading bacteria were isolated from poultry waste. Among those isolates, three strains identified as Bacillus subtilis, Bacillus pumilis and Bacillus cereus degraded feathers effectively and produced 142, 96 and 109 units of keratinolytic activities, respectively. The production of keratinolytic protease by B. pumilis and B. cereus was inducible with feathers, but B. subtilis produced the enzyme constitutively in the presence of various proteins such as casein, feather and BSA. The optimal conditions for the enzyme production by B. subtilis were 40 °C and pH 5-9, for B. pumilis 40 °C and pH 5-6 and for B. cereus 30 °C and pH 7.0. The maximum keratinolytic activities of B. subtilis and B. pumilis were 161 and 149 units/ml after 84 and 72 h of cultivation, respectively. With B. cereus, the maximum enzyme activity was 117 units/ml after 60 h of cultivation. The strains showed maximum enzyme activities in the late logarithmic growth phase or the beginning of stationary phase, and the production of soluble protein showed the same tendency as that of keratinolytic protease.