**1. Introduction**

Rising livestock is a major industry, which produces animals that have multiple uses as meat, fibers and hides. It is important to feed the stock animals a proper balanced diet, to insure optimum growth and health. Feed Industries are seeking new way to cope with raw materials costs [1]. Viable treated feather and hog hair meals have been found valuable sources of dietary protein for the growing chick [2]. Recently, supplementation of poultry diets with enzyme mixtures, including protease and amylase has produced improvements in growth performance [3]. Keratinase is an enzyme hydrolyses a broad range of protein substrate including casein, collagen, elastin and keratin [4]. Scientist reported degradation of chicken feathers and other keratinous waste materials by fungi [5] and decomposed

feathers were utilized as nitrogenous fertilizers due to their high value protein content [6, 7]. This feature of keratin protein can accomplish the shortage of meat raw materials and achieve desire of manufacturer to reduce production costs, and the availability of alternative sources of protein [8]. Feather degradation by microbial action seems to be a reasonable substitute to obtain feather meal that would be nutritionally raised with essential amino-acids. This line of biodegradation of chicken feathers would convert the rigid feather waste to a readily digestible feather meal.

#### **2. Keratin**

Keratin is hardened fiber plus matrix material which ultimately fills the cells of hair cortex. It thus consists of two main components; a fibrous protein which gives the α-keratin x-ray diffraction pattern (or the β-pattern when the polypeptide chains are extended as in feather keratin) and an amorphous protein which is termed γ-keratin [9]. Only rare microorganisms like fungi, bacteria and actinomycetes are capable to break and utilize keratin because of their hard and tough nature. Humans and other vertebrates cannot digest this macromolecule, and if eaten, it simply gets accumulated within the variety of a lump that is still undigested. A large part of tiger scat and other carnivore dung contains scleroprotein (mainly hair) aside from bones and additional complex elements which are undigestible [10]. Animal hair, hoofs, horns and wool contain β-keratin and bird's feather contains α-keratin. Keratins are also present in epithelial covering which is rich in beta helical coil linked through cysteine bridges [11]. The higher the percentage of sulfur, the higher is the stability of keratin towards solubilization [12]. The keratin proteins are compound that are extremely resistant to action of physical, chemical and biological agents. Hair, horns, nails and cornified tissue are some naturally occurring forms of keratin [13–14]. Keratin is a protein macromolecule with very high stability and low degradation rate.

Keratins are categorized into hard and soft keratins according to the sulfur content. Hard keratins have high content di-sulphide linking and are found in appendages. Soft keratins have low content of disulphide bond making skin and callus [15]. Keratins belong to the super family of IF protein. Intermediate filament proteins are planned, prolonged α-helical conformation prone to form twostranded coiled coils. The durability of keratins is a direct consequence of their complex architecture [16].

#### **2.1 Chicken feathers**

The main component of feather is keratin, a mechanically durable and chemically unreactive and insoluble protein, which render it difficult to be digested by most proteolytic enzymes. Keratin is resistant to enzymatic digestion by plant, animals and many known microbial proteases due to insoluble nature. Feathers having only 10% parts which is not keratin, rest 90% is resistant to degradation by common peptidases. This resistance is due to constituent amino acid composition and configuration that provide structural rigidity [17]. Chicken feathers are made up of over 90% of keratin protein, small amounts of lipids and water. Feathers contain about 15% N on a dry weight basis and huge quantities are produced as industrial by product. However, they have not been used effectively as plant bio

**35**

**Table 1**.

*Microbial Hydrolysed Feather Protein as a Source of Amino Acids and Protein in the Diets…*

fertilizers since N mineralization are slow meet plant requirements [18]. Feather waste, resulting in large quantities as by product of poultry farms processing, are

The keratinase producing micro-organisms have been discovered in several

The genera *Burkholderia*, *Chryseobacterium, Pseudomonas* and *Microbacterium* sp. were grown on solid medium with feather meal as sole carbon and chemical elements and screened for proteolytic activity on milk agar plates [19]. Three *Bacillus* species were isolated from the poultry industry and evaluated for keratinase production using feathers or feather meal as the sole carbon and nitrogen sources in a submerged fermentation. *B. subtilis* 1273 was the strain which

exhibited the highest enzymatic activity [17]. A number of keratinases producing *Bacillus* and *Pseudomonas* species have been isolated from various environmental sources such as soil farm wastes and raw feather [20]. *Bacillus* sp., *Bacillus licheniformis*, *Bacillus subtilis* KD-N2, *Burkholderia* was isolated for keratinase production

Thiosulfate production from cystine by keratinolytic prokaryote *Streptomyces fradiae* [23]. Biochemical mechanism of keratin degradation by the actinomycete *Streptomyces fradiae* and the fungus *Microsporum gypseum*: a comparison [24]. Keratinolytic serine protease was purified and characterized from *Streptomyces albidoflavus* [25]. Native keratin decomposition by thermophilic *Actinomycetes* was studied [26]. Keratinase enzyme was isolated and characterized, which was produced during wool degradation process by *Thermoactinomycetes candidus* [27]. Thermoactinomycetes degraded keratin and other collagenous waste by alkaline hydrolysis [28]. A new strain of *streptomyces* was used to degrade feather [29]. A new actinomycetes was isolated from coastal region of south India and studied

The thermophiles may be advantageous in comparison with mesophiles, because of their accelerated reaction processes and the accumulation of biomass and enzymes and diminished the risk of contamination in industrial activity. A large number of keratinases producing fungi were observed by [31]. 234 fungal strains were isolated by baiting method used for feather degradation and keratinase producing ability. Maximum clearing zone was made by *Chrysosporium indicum* on solid agar plates. The highest keratinase production was found in case of *Acremonium strictum* while *Chrysosporium indicum* and *Chrysosporium tropicum* was found next to it [32]. Fungal keratinase reported from India are listed in

different biological groups, including fungi, bacteria and actinomycetes**.**

*DOI: http://dx.doi.org/10.5772/intechopen.96925*

**3. Keratinases from microorganism**

pure keratin proteins.

**3.1 Bacterial strains**

[21–22].

**3.2 Actinomycetes strains**

keratinase production [30].

**3.3 Fungal strains**

*Microbial Hydrolysed Feather Protein as a Source of Amino Acids and Protein in the Diets… DOI: http://dx.doi.org/10.5772/intechopen.96925*

fertilizers since N mineralization are slow meet plant requirements [18]. Feather waste, resulting in large quantities as by product of poultry farms processing, are pure keratin proteins.
