Abstract:

This study aimed to purify and characterize a new feather-degrading enzyme. Twenty bacterial isolates were recovered from different sources on feather-meal medium. The best keratinase producer KR12, isolated from a poultry farm, was selected for the further experiments. Physiological and biochemical studies indicated that the bacterium KR12 belongs to genus Streptomyces. 16S rRNA analysis confirmed this result since the KR12 was similar by 98.8% to Streptomyces radiopugnans. The enzyme was purified using Sephadex G-75 and DEAE (diethylaminoethyl)-Sepharose chromatographic columns. The purified enzyme had a molecular weight of 32 kDa, defined by sodium dodecyl sulfate polyacrylamide gel electrophoresis analysis (SDS-PAGE). The enzyme was active between 30 and 60°C. The enzymatic activity of the purified enzyme was enhanced by Zn2+, Na+, Ca2+, K+, and inhibited by Fe2+, Cu2+, and EDTA, demonstrating that keratinase from Streptomyces radiopugnans KR 12 belongs to metallo keratinases. Keratinase production was enhanced using UV radiation. Three recombinant mutants were obtained, mutant KR II, produced a high keratinase enzyme (3 fold) than the wild strain. Streptomyces radiopugnans KR12 and its mutant are promising for keratinase production and many biotechnological applications.

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