Production and Characterization of Keratinase of a Feather-degrading Bacillus licheniformis PWD-1

Abstract

The keratinase produced by Bacillus licheniformis PWD-1 was induced by feather powder. Maximal enzyme production could be achieved by culturing in a medium containing 1% hammer-milled feather powder (100 mesh) at 45°C for 30h. Maximal growth of PWD-1 was achieved at 50°C, and maximal enzyme induction was at 45°C. The molecular mass and isoelectric point of this enzyme were 31.4 kDa and 8.5, respectively. This enzyme was stable from pH 5 to 12. The optimal reaction pHs for feather powder and casein were 8.5 and 10.5 to 11.5, respectively. The optimal reaction temperature was 50°C to 55°C. The relative activity of this enzyme toward casein, feather powder, keratin, elastin, and collagen was 1OO:52:41:18:7, and 100:56:32:3 for Suc-AAPL-pNA, Suc-AAPF-pNA, Suc-AAPM-pNA, and Suc-AAVA-pNA (Suc, succinyl ; pNA, p-nitrophenylanilide).