Cloning and expression of acidstable, high maltose-forming, Ca2+-independent α-amylase from an acidophile Bacillus acidicola and its applicability in starch hydrolysis

The alpha-amylase encoding gene from acidophilic bacterium was cloned into pET28a(+) vector and expressed in BL21 (DE3). The recombinant produced a 15-fold higher alpha-amylase than strain. The recombinant alpha-amylase was purified to homogeneity by one-step nickel affinity chromatography using Ni2+-NTA resin with molecular mass of 62 KDa. It is active in the pH range between 3.0 and 7.0 and 30 and 100 A degrees C with optimum at pH 4.0 and 60 A degrees C. The enzyme is Ca2+-independent with (m) and (cat) values (on soluble starch) of 1.6 mg ml(-1) and 108.7 s(-1), respectively. The alpha-amylase of is acidstable, high maltose forming and Ca2+-independent, and therefore, is a suitable candidate for starch hydrolysis and baking.