Abstract

Response surface methodology was used to study the cumulative effect of the nutritional parameters and to enhance the production of extracellular α-amylase in solid-state fermentation by Thermomyces lanuginosus ATCC 58157. These nutritional parameters considered include carbon source (soluble starch), nitrogen source (peptone) and a concentrated mineral medium. For obtaining the mutual interaction between the variables and optimizing these variables, a 2³ factorial central composite design using response surface methodology was employed. The optimal calculated values of tested variables for maximal production of α-amylase were: soluble starch, 71.10 g/Kg; peptone, 91.97 g/Kg and mineral salts solution, 175.05 ml/Kg with a predicted α-amylase activity of 5.085 ´ 10⁵ U/Kg of wheat bran. These predicted optimal parameters were tested in the laboratory and the final α-amylase activity obtained, 4.946 ´ 10⁵ U/Kg of wheat bran, was very close to the predicted value.

Key words: α-Amylase, Thermomyces lanuginosus, solid state fermentation, optimization, response surface methodology.