Valorization of feather via the microbial production of multi-applicable keratinolytic enzyme

Abstract

The keratinous structure of feathers is an attractive proposition for its incorporation in various biotechnological applications. In the current study, feather was used for the bacterial production of keratinase under submerged fermentation using Bacillus haynesii ALW2 with optimum productivity of 92.9U/mL. Additionally, the enzyme activity after partial purification was optimized in respect to the effects of temperature and pH in which the optimum activity was achieved at 70οC and over a pH ranged from 8 to 9. Thermal stability study indicated that the half-lives of the enzyme were 234.41, 75.24, 37.48 and 31.87 min-1 at 40, 45, 50 and 55οC, respectively. By studying the effects of different substrate concentrations, the values of Km, Vmax and Kcat were indicated as 10 mg/mL, 2500U/mg protein/min and 1.45min-1, respectively. The potential application of the partial pure enzyme in leather and detergent industry was examined. Results indicated that the enzyme achieved complete dehairing of cow-hide after 6 h incubation at 37οC in addition to its efficiency in removing protein-rich stains within 30 min at 50οC. Moreover, the enzyme activity in the degradation of feather indicated the degradation percentage of 60% with the release of a combination of amino acids as confirmed by thin layer chromatography analysis. Finally, the amount of the soluble protein was indicated to be 0.379 mg/mg dry hydrolysate with antioxidant activity of 70.8 μg Trolox Equivalents/mg.