Keratinase is a type of extracellular, inducible proteolytic enzyme that can degrade keratin substrates that are insoluble. This enzyme can hydrolyze hair, feathers, and collagen in the sewage system during wastewater treatment. Additionally, it is useful in the food industry and the manufacturing of livestock feed, etc. Enzymatic hydrolysis of insoluble feather keratin using the keratinase enzyme from the poultry sector can be utilized to make adhesives, livestock feed, fertilizers, coatings, or uncommon amino acids such as serine, cysteine, and proline.
It is a protease enzyme that degrades keratin selectively. Keratinase is an adaptive enzyme that is only produced in response to the introduction of an inducer (keratin) in the microenvironment. The keratinase enzyme is extracted from a variety of microorganisms and has a wide range of applications in feed, leather, pharmaceuticals, food, and many other industrial as well as major ecological applications.
Mechanism of Action
Because the mechanism through which each bacteria destroys keratin is different, the end product also differs. Certain fungi break disulfide bonds by secreting sulfites on the mycelium surface and reducing the acidic conditions, while Streptomyces produces intracellular reductase. Water-insoluble keratin, on the other hand, can only survive outside the cell in the form of granules. Since it necessitates insoluble keratin in frequent proximity with cells, disulfide bond reduction can only happen outside of the complete cell with significant metabolic capabilities, very possibly in the cell-bound redox system on the cell membrane.
The disulfide bond reduction is then carried out by a cell-linked redox pathway in white, high-temperature actinomycetes. Keratinase is an enzyme that possesses both disulfide reductase and polypeptide hydrolase actions. The breakdown of keratinase is currently thought to be separated into three stages: denaturation, hydrolysis, and transamination. Firstly, the disulfide reductase reduces cystine (-S-S-) to cysteine (-SH), causing the high-level composition of keratin to dissolve and resulting in degenerative keratin proteins. Polypeptide hydrolase progressively hydrolyzes the degenerative keratin protein into polypeptides, oligopeptides, and free amino acids. Finally, transamination produces ammonia and sulfur dioxide, which totally hydrolyze keratin.
Industrial Production of Keratinase Enzyme
Fermentation is required to generate these enzymes on a large scale in an effort to match current industry demands. Fermentation factors like carbon source, nitrogen source, temperature, and others must all be optimized because they influence keratinase enzyme synthesis. Industry waste, like feathers, can be incorporated into cultural media. Different wastes, like wheat and soybeans, can also be employed as a substrate for keratinase enzyme production.
Keratinase enzymes must be purified before they may be used for enzymatic characterization and other purposes. A variety of methods can be used to achieve high purity of the keratinase enzyme. Purification procedures include ammonium sulfate precipitation, gel filtration chromatography, and ion exchange chromatography. To acquire a large number of enzymes, methods like the aqueous two-phase system can be used.
Application of Keratinase Enzyme
Keratin is considered a good source of carbon, nitrogen, and sulfur that can be transformed into a variety of compounds in nature. Because of their propensity to break down keratins, keratinase enzymes have a wide range of industrial and biotechnological applications.
Livestock Feed Industry
Feather food has been used to enrich livestock feed for years, but there has been concern regarding the food’s nutritional content given the lack of utilizable protein in the food. Since they’re not digested by ruminants or other livestock, keratin proteins in feathers, as well as other keratinous substances, are mainly unreachable if the structural orientation given by distinct chemical groups is not dramatically fragmented.
Leather Industry
The use of a keratinase enzyme to dehair is substantially enhanced as it has minimal elastolytic action but zero collagenolytic action. Keratinases specifically break down the keratinous element of the follicle, allowing undamaged hairs to be removed without harming the leather’s quality. The use of keratinase in the leather industry has also decreased the possible danger to the environment caused by traditional procedures, but it has also created practices that can improve energy efficiency worldwide.
Detergent Industry
Detergents produced with bio-additives such as Keratinase enzymes are preferred over traditional synthetic-based detergents in modern times. They offer excellent cleaning features, like low-temperature washing tolerance, stubborn dirt-removing properties, fabric fibre compatibility, and biodegradability. Numerous factors influence the overall effectiveness of keratin enzymes in detergents.
Fertilizer Industry
The prospect of bioconversion of the high-content keratin wastes into cost-effective and environmentally acceptable resources, such as a slow-releasing nitrogen source for natural and organic soil fertilizer, The organic fertilizer produced by keratinase-mediated waste mineralization can promote the growth of plants, enhance soil water retention capacity, and promote soil microbial activity, which would also promote phosphate solubility.
Pharmaceutical and Cosmetic Industry
The keratinase enzyme is also useful in the cosmetics and pharmaceutical industries. Dermatophytes produce keratinase enzymes, which are a key invasive component. As a result, a useful study direction in keratinase and dermatophyte infection is whether keratinase inhibitors or keratinase monoclonal antibodies can limit keratinase enzyme function, diminish the invasiveness of dermatophytes, and reach the objective of treating fungal diseases.
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