Expression and biochemical characterization of a novel type I pullulanase from Bacillus megaterium

To identify novel pullulanases from microorganisms and to investigate their biochemical characterizations. A novel pullulanase gene (BmPul) from Bacillus megaterium WW1210 was cloned and heterologously expressed in Escherichia coli. The gene has an ORF of 2814 bp encoding 937 amino acids. The recombinant pullulanase (BmPul) was purified to homogeneity and biochemically characterized. BmPul has an MW of approx. 112 kDa as indicated by SDS-PAGE. Optimum conditions were at 55 A degrees C and pH 6.5. The enzyme was stable below 40 A degrees C and from pH 6.5-8.5. The Km values of BmPul towards pullulan and amylopectin were 3.3 and 3.6 mg/ml, respectively. BmPul hydrolyzed pullulan to yield mainly maltotriose, indicating that it should be a type I pullulanase. A novel type I pullulanase from Bacillus megaterium was identified, heterologously expressed and biochemically characterized. Its properties makes this enzyme as a good candidate for the food industry.