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Production of a thermostable amylase by yeast strainisolated from sahariansoils cultivated in Soft cheese whey | Abstract
Scholars Research Library

Scholars Research Library

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Abstract

Production of a thermostable amylase by yeast strainisolated from sahariansoils cultivated in Soft cheese whey

Author(s): S. Toumi, A. Tifrit, D. Hadjazi, Z. Chama and B. Abbouni

Eleven yeasts strains were isolated from Saharian soils Bechar and Ouargla(Algeria), screened for their ability to produce amylases. Phenotypic characterization of these amylases producing strains revealed the prominence of ascomycetous yeasts. A selected strain, Schwanniomyces sp, showed the highest amylase activity on starch agar plate. This work investigated the capacity of the yeast LB3 of producing amylolytic enzymes through fermentation in culture medium, based on soft cheese whey to 100% deproteinized and supplemented with soluble starch to 1%.The yeast LB3 showed the highest peaks of enzymatic production at 56 h, where 4796 U/ml of amylase were obtained at 30°C and pH 5. The optimum enzyme activity was displayed at 60°C and pH 6. About 91%and 85%of the activity retained after heating the crude enzyme solution at 60°C and 70°C respectively for 2 h and enzyme was completely inactivated when heated at 120°C for 190min. The extracellular amylase was found to be thermostable and active at wide range of pH. Of the carbon sources, Wheat starch was found to be very carbon source for enzyme production. Yeast extract and ammonium nitrate (0.2%) as nitrogen sources gave higher yield compared to other nitrogen sources. The enzyme was strongly inhibited by Zn2+, Fe2+,Hg2+, Cu2+ andAg+but stimulated by Ca2+ and Mn2+. Enzyme was very sensitive to SDS (2%)and inhibited by 5 mM EDTA.


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