Production and properties of the highly efficient raw starch digesting α-amylase from a Bacillus licheniformis ATCC 9945a

Highly efficient raw starch digesting alpha-amylase was produced after 24 h of batch fermentation of Bacillus licheniformis ATCC 9945a in laboratory bioreactor at 37 degrees C. The enzyme was purified by gel filtration chromatographies with 6-fold increase of specific activity and 38% recovery and showed a molecular mass of 31 kDa by SDS-PAGE. The purified enzyme had an optimum pH of 6.5 and optimum temperature of 90 degrees C. The purified alpha-amylase in the presence of CaCl(2) retained 55% of its activity after 6 h of incubation at 70 degrees C. Co(2+), Ni(2+) and Ca(2+) slightly stimulated, while Hg(2+) completely inhibited alpha-amylase activity. Hydrolysis rates of raw triticale, wheat, potato, horseradish and corn starches, at 1% concentration were 63, 60, 59, 52 and 37%, respectively, in a period of 4 h. The properties of the purified enzyme proved its high efficacy for digesting diverse raw starches below gelatinization temperature and, hence, its potential commercial value to use as an industrial enzyme. (C) 2010 Elsevier B.V. All rights reserved.