The potential industrial application of Bacillus amyloliquefaciens EGY3 keratinolytic protease: optimization, characterization and application as eco-friendly sustainable alternative in leather and detergent industry

Keratinolytic proteases are proteolytic enzymes specifically catalyse keratin hydrolysis that have been seen as efficient eco-friendly bio-catalysts for various industrial processes. In this study, an isolated keratinolytic bacterial strain namely Bacillus amyloliquefaciens EGY3 (Genbank accession number PP038117) was used for the enzyme production under submerged fermentation of feather in which the addition of corn steep liquor possessed a positive impact on the enzyme productivity. Furtherly, the fermentation conditions was statistically optimized and the optimized enzyme activity (391.5 ± 3.50 U/ml) was increased by 5.5-fold. Moreover, the partially purified enzyme was estimated to be alkalophilic (optimum activity at pH 9), thermophilic (optimum activity at 70°C) and surfactant stable enzyme. By examining the generated enzyme's suitability for dehairing bovine hide, complete dehairing was achieved after 2 h with the production of smooth clean surface and without the estimation of any negative impact on the skin structure manifested by scanning electron microscopy. Finally, the enzyme's possible application in getting rid of a stain made of proteins (chocolate-flavored milk stain) from cotton fabrics was examined in which the enzyme addition to a thermally-inactivated commercial detergent restored the whiteness index of the treated fabric by 86.28 % in compare to 65.26% for the use of the commercial detergent.