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

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.