An efficient cloth cleaning properties of a crude keratinase combined with detergent: towards industrial viewpoint

Production of alkaline keratinolytic protease related to various industrial applications, especially for enzyme detergents combination, was done from a selected bacterial strain Paenibacillus woosongensis TKB2. Enzyme yield was maximized by optimizing the culture conditions of a low-cost culture medium under submerged condition with a lab scale fermentor of 5 L capacity. The highest keratinolytic activity was obtained 76.05 U/mL by maintaining fermentation conditions of keratinase production at 30 °C, 40% dissolved oxygen level at 500 rotations per minute (rpm) and an initial pH of media of 8.5 supplemented with 0.76% chicken feathers. In fact, the crude enzyme showed four proteolytic zones in casein zymography which revealed that the crude keratinase contained four hydrolytic enzymes. The crude keratinase was active in broad range of pH (7–10.5) with keratin as a substrate. However, it exhibited highest activities at pH 9. The crude keratinase which was strongly inactivated by Phenylmethylsulfonyl fluoride (PMSF), aprotinin and leupeptin, indicated that it was a serine type protease. The crude enzyme showed remarkable stability with EDTA and was compatible with commercially available detergents. The enzyme bead prepared by 1.5% CMC improved significant storage stability with commercial detergent powder making it suitable for commercial exploitation. The alkaline keratinase of P. woosongensis TKB2 showed a potential application in the laundry industry by removing the blood stains from the surgical cloths and gave a remarkable result towards removing the composite stain of blood, egg yolk and chocolate stain in a short period without changing texture, strength (27.18 g/tex) of cloths and cloths fibers. The effluents generates after cloth washing with this detergent formulation does not effect on aquatic ecosystem. Thus, this aqua-friendly detergent formulation can be used to avoid pollution problems associated with effluent generates after cloths washing.