Keratinase

Keratin is an insoluble proteins present inthe epidermis and important composition of feather, hair, wool, nail, hoofand horns.Keratin is important composition and provide strength to the keratinous substrate.In the environment, feather, hair, wool, nail, hoof and horns are considered as waste material and are major causes of environmental pollution.Keratin is also found in products of agro-industrial processing, dairy industry, poultry farms and slaughterhouses.These keratinous waste are structurally stable and very hard to degrade.The keratinous waste can be managed by biological degradation.Microbial keratinase present in some species of bacteria and fungi is best for the degradation of keratin waste in natural condition.The present review paper explains keratinolytic microorganisms and their keratinase for the biological degradation of keratin waste.

Microbial keratinase mediated biodegradation of keratin rich wastes such as chicken feathers, nails, hairs and wool, is an environmentally-friendly process, which converts profuse waste into low-cost, nutrient-rich materials such as biofertilizer and animal feed. In the present paper soil samples collected from different poultry farms located in Bikaner were screened for keratinase production. The investigation resulted in isolation of 96 bacterial isolates, out of which 15 were confirmed keratianse producers as determined by their hydrolytic activity on Keratin Powder (KP) agar medium. On the basis of higher keratinase activity (11.6 U/ml) bacterial isolate S-5 was selected and evaluated for detergent stability and wash performance. The bacterium was identified as a strain of Bacillus tequilensis. This keratinase was stable in different detergents and exhibited potential to remove coffee and blood stains from cotton fabrics when used alone. However, better stain removal was observed when it was used along with 0.2 % detergent solution.

Microbial keratinase mediated biodegradation of keratin rich wastes such as chicken feathers, nails, hairs and wool, is an environment friendly biotechnological process, which converts this abundant waste into low-cost, nutrient-rich animal feed. Keratinase mediated hydrolysis of feather meal/raw feather significantly enhances the level of essential amino acids in the product. Optimization of various physical and nutritional parameters showed that maximum protease production of 4250 U/l from Bacillus S-2 strain occurred in 36 h at pH 7, temperature 37 ºC, agitation rate 200 rpm, in a medium having lactose as carbon source, proteose peptone as nitrogen source and 1 % feather meal as inducer. The isolated enzyme efficiently degraded raw feathers to soluble form in 48 h of incubation at 37 ºC and 150 rpm. The enzyme has the potential for application in the manufacturing of organic manure and production of nutrient rich animal feed. The enzyme was compatible with detergents and removed stains of blood, egg white and coffee more efficiently than the detergent alone, so can also be used as a detergent aid.