Keratinolytic Enzyme from a Thermotolerant Isolate Bacillus sp. NDS-10: An Efficient Green Biocatalyst for Poultry Waste Management, Laundry and Hide-dehairing Applications

• Published in: Waste and biomass valorization Vol. 12; no. 9; pp. 5001 - 5018
• Main Authors: Akram, Fatima, Haq, Ikram ul, Hayat, Afifa Khizer, Ahmed, Zeeshan, Jabbar, Zuriat, Baig, Iqra Moazzam, Akram, Rabia
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01-09-2021; Springer Nature B.V
• Subjects: Animal wastes; Bacillus; Bioconversion; Biodegradation; Degradation; Detergents; Engineering; Environment; Environmental Engineering/Biotechnology; Enzymes; Feathers; Formulations; Industrial Pollution Prevention; Keratin; Keratinase; Keratinocytes; Laundry; Microorganisms; Modulators; Optimization; Original Paper; pH effects; Proteolysis; Renewable and Green Energy; rRNA 16S; Waste management; Waste Management/Waste Technology; Biodegradation; Dehairing; Keratinase; sp. NDS-10; Optimization
• ISSN: 1877-2641; 1877-265X
• DOI: 10.1007/s12649-021-01369-2

Background:
The enzymatic degradation of keratin-rich wastes by a keratinolytic microorganism is a preferable and eco-friendly biotechnological alternative for the valorization of these compounds. Despite their recalcitrant behavior, hydrolysis of these wastes can be efficiently done by microbial proteolytic enzyme known as keratinase.
Objective:
In the present study, a potent keratinolytic bacterial strain with a great potential of feathers’ degradation was isolated and identified by 16S rDNA sequencing as Bacillus sp. NDS-10.
Results:
After optimization, high-yield of extracellular keratinase (92 U mL
−1
) and bioconversion of feathers (97%) were achieved in M9 medium (pH 7.0) containing 0.8% (w/v) native chicken feathers after 20 h incubation at 45 °C. The crude keratinase exhibited maximal activity at pH 7.0–8.0 (Tris-Cl buffer) and 65 °C; and showed great stability over a range of pH (6.0–10.0) and temperature (20-60°C) for 6 h. No inhibitory influence was observed with various chemical modulators, commercial detergents and salt but phenylmethanesulfonyl fluoride (PMSF) completely repressed the keratinolytic activity of enzyme. The enzyme effectively dehaired goat hide after 6 h without any damage and completely removed the blood-stain after 5 min incubation.
Conclusion:
These favorable features indicated that this keratinolytic enzyme seems to be an efficient and eco-friendly candidate for keratin-waste management, detergents formulations and hide-depilation application.
Graphic Abstract