Abstract

This study is concerned with the production and optimization of alpha amylase by Bacillus amyloliquefaciens IIB-14 in the presence of additional carbon and nitrogen sources using solid state fermentation. Alpha amylase is of special importance in the starch fermentation industry, as it has significant commercial applications in starch processing, beverages, foods, bread and baking, medicines, textile, paper, pharmaceuticals, sugar and detergent industries. Maltose, glucose, lactose and soluble starch were supplemented as carbon sources. Urea, peptone, yeast extract and nutrient broth as organic nitrogen sources while NH₄NO₃, (NH₄)₂SO_4, NaNO₃ and KNO₃ as inorganic nitrogen sources were evaluated. Among them, a marked improvement in enzyme production (70.15 U/mg/min) was obtained with lactose, yeast extract and NH₄NO₃ at a level of 1.5, 1 and 1%, respectively. The performance of fuzzy-logic system control was found to be highly promising for the improved substrate conversion rate of more than 75%. The process parameters were further identified using Plackett-Burman design. The correlation (1.045E+0025) among variables demonstrated the model terms as highly significant (HS) indicating commercial utility of the culture used (p<0.05). The maximal enzyme activity (84.24 U/mg/min) of crude enzyme was found at pH 7 and temperature 70°C incubated for 30 min.

Key words: Alpha amylase, Bacillus amyloliquefaciens, solid state culture, carbon and nitrogen supplementation, fuzzy-logic control, two-factorial experimental design