Keratin Degradation by Penicillium purpurogenum Isolated from Tannery Soils in Jos, Nigeria

Background: Tannery soils are very rich in keratinous materials such as fur, wool and hair that are by-products of the tanning industry where hides and skins are processed. A keratinase producing fungus belonging to the genus Penicillium was isolated from soils containing tannery wastes in Jos, Plateau State Nigeria.
Materials and Methods: The fungus produced extra cellular protease on skim milk casein agar as an indication for keratinase production. The species had maximum proteolytic and keratinase activities in a Submerged Fermentation (SmF) using liquid basal medium supplemented with skim milk, chicken feathers and human hair as carbon and nitrogen sources.
Results: The Spectrophotometric assay of the proteolytic and keratinolytic activity of Penicillium purpurogenum, showed that it had the highest activity (13.5 U/ml) on chicken feathers. This was followed by human hair with activity of 12 U/ml. The least activity of 11.9 U/ml was observed in skim milk medium. It was observed that incubation temperature had an effect on the enzyme activity, with an optimum temperature of 37°C for both protease and keratinase.
Conclusion: This non-dermatophytic keratinolytic fungus may have potential use in biotechnological processes involving keratin hydrolysis. The results of this work reiterated that keratinolytic activity is relatively widespread among common fungi and may have an important role in keratin degradation in the natural environment.