Purification and characterization of a keratinase from the feather-degrading cultures of Aspergillus flavipes

Abstract

Keratinase was purified and characterized from the solid cultures of Aspergillus flavipes using chicken feather as substrate under solid state fermentation. The enzyme was purified by about 2.67 fold compared to the crude enzyme preparation. 40-60% ammonium sulphate saturation was used followed by anion exchange chromatography and gel filtration. The molecular weight of the enzyme under denaturing conditions was 60 KDa. The optimum pH and pH stability range were 7.0 and 5-8, respectively. The enzyme activity was significantly inhibited by incubating with EDTA, Hg⁺², Fe⁺³, while it was not apparently affected by the presence of Zn⁺², Mg⁺² and Cu⁺². The enzyme has a wide proteolytic activity towards casein, albumin and gelatin, related to the standard keratin, which makes their wide biotechnological applications justifiable.

Key words: Keratinase, Aspergillus flavipes, solid state fermentation.