School of Chemical and Bio Engineering

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Browsing School of Chemical and Bio Engineering by Author "Abebe, Birhanu"

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    Dehairing Protease Production and Evaluation of The Efficacy of Protease Products of Relevant Downstream Processing
    (Addis Ababa University, 2014-09) Abebe, Birhanu; Kuppuswami, Gowthaman M. (PhD)
    Globally as well as in Ethiopia the tanning industries are under a high pressure from strict legislation articulated for the purpose of protecting and preserving the environment. In the current situation of Ethiopia this industry is viewed from two perspectives; being an important economic activity and the most environment polluting industry. In order to operate within environmentally compatible limits and sustain the realization of Agriculture Development Led Industrialization (ADLI), the current development strategy of Ethiopia, with respect to the tanning industry, some sort of solutions should come out that mitigate the adverse effect of the conventional leather processing methods particularly that of lime-sulphide unhairing operation. This study deals with dehairing enzyme production as green technology alternative for the conventional unhairing practice. The B.subtilis strain was obtained from Department of Biotechnology, CLRI, sub-cultured and characterized for its growth and dehairing protease production in terms of pH, temperature, incubation time and growth and production media composition. The combined effects of pH and temperature on protease production also investigated and they were found to have high interactive effect. Once the culture conditions for production were studied and known, the alkaline protease was produced in a pilot scale fermenter by submerged fermentation using soy bean flour media at optimal conditions of pH 6.5, temperature 310C and incubation period of 27 hours. The final protease product was recovered, partially purified and stabilized by primary downstream processing such as crude enzyme formulation, ammonium sulphate precipitation, ultrafiltration and spray drying. The use of the protease products of each technique on sheep skins and cow hide resulted in a highly promising hair removal efficiency that can really compete with lime-sulphide chemical unhairing process.