Production, Characterization, and Potential Application of A Keratinolytic Alkaline Protease Produced by Alkaliphilic Vibrio Sp.
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Date
2011-05
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Addis Ababa University
Abstract
At present alkaline proteases are widely used in leather processing, detergent formulations,
silver recovery process, and in the production of protein hydrolysates. All alkaline proteases
are dervied from microbial sources that grow on expensive growth substrate. Many studies
showed that nearly 40% of the production cost of alkaline proteases is accounted for by the
growth substrate. To reduce the production cost it is important to search for microorganisms
capable of growing and producing suffiecient amount of the enzyme using cheap substartes.
In this regard keratinacious wastes released by poultry and leather tanning industries has an
enourmous potential to serve as growth substartes for protease production. In this study, a
protease producing Vibrio sp. capable of growing on bovine and sheep hair was isolated from
Lake Arenguade. The organism produced appreciable level of keratinolytic protease using
hair as the sole source of carbon and nitrogen. The enzyme was active in the pH range of 7.0-
11.5 and 40-70°C with an optimum pH of 11.0 and 50oC. The enzyme showed good stability
in the presence of oxidizing agents and detergents. Application of the enzyme at the inner
side sheep skin at a dosage of 58U/ml, pH 10.0 brought about complete removal of hair
within 24 h at room temperature and 12 h at 37oC. Protease R-11 was also tested for the
recovery of silver from used x-ray films. At enzyme dose of 11.6 U/ml and at 55oC complete
removal of the gelatin layer of used x-ray films was achieved within 3 min at pH 10.00.
These results indicate the potential of protease R-11 for multipurpose industrial application.
Because the organism produces the enzyme using cheap substrates, hair, its production cost is
expected to be very low.
Key words: Dehairing; Gelatin hydrolysis. Hair degrading; Keratinolytic protease; Keratinous
wastes; Used x-ray film; Vibrio sp. strain R11
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Keywords
Dehairing, Gelatin hydrolysis, Hair degrading, Keratinolytic protease, Keratinous wastes, Used x-ray film, Vibrio sp. strain R11