[Extracellular thermostable alpha-amylase from Bacillus licheniformis B7].
A thermostable alpha-amylase producing bacterium has been isolated from soil and identified as Bacillus licheniformis B7. Cultural conditions of this strain for alpha-amylase production were studied. The optimum temperature and incubation period for enzyme production were 50 degrees C and 7 days respectively. Starch with a concentration of 2.5% was the best carbon source for enzyme production. Besides the above conditions, the addition of 0.05% FeCl3 X 6H2O, 0.6% yeast extract, 0.35% peptone, 0.2% Na-citrate and 0.008% CaCl2 X 2H2O to the growth medium produced maximum enzyme activity. The alpha-amylase produced by this strain showed maximal activity at 90 degrees C and pH 9.0.