الفهرس 
AcknowledgementOnly 14 pages are availabe for public view
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Abstract
Keratin - containing materials such as hair, nail, wool, hooves, horns, and feather are abundant in nature. (1) Although, keratin in its native state, is indigestible by common proteolytic enzymes such as pepsin, trypsin, and papian due to high degree of cross - linking by disulfides bonds, hydrogen bonds, and hydrophobic interactions, it does not accumulate in nature. Consequently, it is considered a real source of pollution. (2 - 6) On the other hand, keratin - containing materials, especially feathers that are hydrolyzed by physical and chemical treatments, can be converted to feedstuffs, fertilizers, and glues can be used in the production of soluble proteins, amino acids and peptides. (7) However, these treatments require significant energy and actually destroy certain amino acids. (8) These limitations addressed the indispensable need for the use of alternative biotechnological methods. (9)
Several previous reports highlighted the isolation of many keratinolytic microorganisms and their uses in the bioconversion of keratin- containing materials as an alternative method. (10 - 17) The development of bioprocess using keratinolytic microorganisms addresses three important needs; ecological, because the degradation of keratins in the environment leads to the production of sulfur compounds; nutritional, by generating a product with better digestibility and nutritional value; and economical, because the current processes are expensive. (9) A previous detailed study reported the formation of some useful products as a result of feather degradation directed by the feather - degrading Bacillus subtilis DB 100 (pS1) cells. (18)