Keratin Degradation by Penicillium purpurogenum and Aspergillus niger Isolated from Nigerian Soils Polluted with Tannery Wastes | Chapter 09 | Recent Advances in Biological Research Vol. 2
Background:
Keratinophilic fungi are a group of fungi that colonize various keratinous
substrates and degrade them to components of low molecular weight. Keratinized
tissues include feathers, beaks of birds, horns, hooves, skins, hair, fur,
wool, nails and claws of animals. 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. Keratinase producing fungi,
Aspergillus niger and Penicillium purpurogenum were isolated from soils containing
tannery wastes in Jos, Plateau State Nigeria.
Materials
and Methods: Skim milk casein agar was employed to
assay for extra cellular protease 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. Effects of
incubation temperature on protease and keratinase enzyme activity were also
determined.
Results:
The Spectrophotometric assay of the proteolytic and keratinolytic activity
showed that P. purpurogenum 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. Similar results were
recorded for A. niger with highest activity of 11.8 U/ml on chicken feathers.
This was followed by human hair with activity of 10.6 U/ml while skim milk agar
had the least activity of 10.0 U/ml. It was observed that incubation
temperature had effects on the enzyme activity, with an optimum temperature of
37°C for both protease and keratinase.
Conclusion:
These non-dermatophytic keratinolytic fungi 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. P. purpurogenum and A. niger bio-degraded skim milk
casein, human hair and chicken feather in Submerged Fermentation (SmF). They
had the greatest activity on chicken feathers indicating that they could be
employed in waste and environmental pollution management. In Nigeria, poultry
feathers, animal hair and other keratin sources including tannery wastes do not
find suitable applications. Practical use of keratinase producing
microorganisms such as the ones used in this study is being explored in applied
microbiology where there is great need for active degraders for the management
of keratin containing wastes.
Biography of author(s)
Dr. (Mrs.) Abigail Ify
Ogbonna (Ph. D.)
Department of Plant Science
and Biotechnology, University of Jos, P.M.B.2084 Jos, Nigeria
View Volume: https://doi.org/10.9734/bpi/rabr/v2
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