Purification and Partial Characterization of an Acidic alpha-Amylase from a Newly Isolated Bacillus subtilis ZJ-1 that may be Applied to Feed Enzyme

摘要

An amylase-producing strain was isolated from soy sauce and designated as Bacillus subtilis ZJ-1. Purification of a-amylase from B. subtilis ZJ-1 to homogeneity by ethanol fractionation, ultrafiltration, and Sephadex G-100 gel filtration resulted in recovery of 8.9% and a specific activity of 542.7U= mg protein. The molecular mass was estimated to be 58 kD by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). The enzyme reached its maximum activity at a pH of 5.0 and a temperature of 50 degrees C. The enzyme remained at 89.4 +/- 3.0% of its activity at 40 degrees C. The enzyme retained 87.7 +/- 3.7% and 63.4 +/- 2.9% of its original activity at 40 degrees C after a 60-min incubation in the presence of 5mM CaCl2 at a pH of 5.0 and 4.0, respectively. These properties indicate that the novel enzyme has a theoretically high survival rate and excellent starch catalytic efficiency in the typical chicken gastrointestinal-tract environment (pH 3.5-7.0, 40 degrees C). In addition, the enzyme remained at 78.4 +/- 3.6% of its activity after a 5-min incubation at 80 degrees C, which demonstrates that the enzyme could maintain a high survival rate in the pelleting process of feed production. The characteristics just described make this enzyme a good candidate for use as a chicken feed enzyme.

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