High-level expression, purification and characterization of a recombinant medium-temperature alpha-amylase from Bacillus subtilis.

Alpha-amylases are important industrial enzymes with a wide range of applications. Although medium-temperature alpha amylase (AmyE) has some practical advantages, its low yield has limited its applications. When an amyE gene from Bacillus subtilis BF768 was cloned into vector pWB980 and over-expressed in B. subtilis WB600, high activities (723 U ml(-1)) of secreted AmyE were produced. Recombinant AmyE was purified to a specific activity of 36 U mg(-1) having optimal activity at pH 6.0 and 60 degrees C.