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PRODUCTION, PURIFICATION AND SOME PROPERTIES OF EXTRACELLULAR KERATINASE FROM FEATHERS-DEGRADATION BY ASPERGILLUS ORYZAE NRRL- 447

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Author(s): THANAA H. ALI | NADIA H. ALI | LATIFA A. MOHAMED

Journal: Journal of Applied Sciences in Environmental Sanitation
ISSN 0126-2807

Volume: 6;
Issue: 2;
Start page: 123;
Date: 2011;
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Keywords: Aspergillus oryzae NRRL 447 | feather degradation | keratinase production | purification | properties

ABSTRACT
Extracellular keratinase was produced during submerged aerobic cultivation in a medium containing chicken feather for enzyme synthesis. The en­zyme was partially purified by acetone fractionation and DEAE-Sephadex A-25 column chromatography. A purification fold about 20.7 with a yield of 37.9% as determined with keratin as substrate of the activity in crude extracts. Specific activity of this partially purified enzyme is 2312.7 U/mg.  The km and Vmax values were 7.15 mM and 300U/ml respectively. The optimal pH and temperature for keratinolytic activity was approximately 7.0 and 70°C respectively. Essential amino acids like threonine, valine, methionine, isoleucine, leucine, lysine, histidine and tyrosine as well as ammonia were produced when feathers were used as substrates. Exposures of purified keratinase in absence of substrate at 80°C, for 60 minutes caused lose about 56% of its activity. This keratinase was inhibited in a variable rates by addition of EDTA, CuSO4, ZnCl2 MnCl2 and HgCl2 at a concentration of 15mM, where as iodoacetate and 2-mercaptoethanol slightly activation at the same concentration. Strain Aspergillus oryzae, therefore, shows great promise of finding potential applications in keratin hydrolysis and keratinase production.

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