Extracellular α-Amylase Production byBacillus brevisMTCC 7521

Alpha amylases have various applications in food processing industries, for example, baking, brewing and distillery industries. Studies of the Ca2+ independent α-amylase production were carried out by a strain of Bacillus brevis MTCC 7521 isolated from a brick kiln soil. The optimum temperature, pH and incubation period for amylase production were 50°C, 6.0 and 36 h, respectively. The enzyme secretion was at par in the presence of any of the carbon sources (soluble starch, cassava starch and cassava flour). B. brevis produced more amylase in presence of beef extract as nitrogen source in comparison to other organic nitrogen sources (peptone, yeast extract and casein) and asparagine, potassium nitrate, ammonium sulphate, ammonium nitrate and urea reduced the enzyme activity. The addition of Ca2+ (10–40 mM) or surfactants (Tween 20, Tween 40, Tween 60, Tween 80, and sodium lauryl sulphate at 0.02% concentration) in culture medium did not result in further improvement in the enzyme production. The purified enzyme had a molecular mass of 205 kDa in native SDS-PAGE.