Keratin hydrolysates: a sustainable product in biotechnology sectors by microbial conversion

The increasing population and demand for food and feed have increased the urge to find protein sources from waste products. Due to poor management of waste valorization, it has become a pollutant to the environment. This waste can be converted into a valuable product by microbial degradation. Feather waste from poultry farms can be efficiently processed into hydrolysates, serving as an additive or in its crude form for animal feed and detergents. This approach not only reduces pollution but also boosts the economy of a country. Keratin is a hard fibrous protein, insoluble in water and organic solvents. They are accumulated in nature and are major components of feathers, nails, hairs, and wool. Microorganisms like bacteria, fungi, and actinomycetes can degrade keratin by producing the keratinase enzyme. Keratinases are thought to be promising biocatalysts for the production of animal nutrients, protein supplements, leather processing, fibre modification, detergent formulations, and pharmaceutical, cosmetic, and biomedical industries. An overview of keratin structure and composition, the mechanism of microbial hydrolysis of keratin, and their possible uses in biotechnological sectors are presented in this review.