[Purification and characterization of an endo-beta-1, 4-mannanase from Bacillus subtilis BM9602]

An extracellular neutral endo-beta-mannanase(endo-beta-1, 4-D-mannan mannanohydrolase, EC 3.2.1.78)of Bacillus subtilis BM9602 was purified to electrophoretic homogeneity by ammonium sulfate precipitation and DEAE-cellulose DE22 chromatography with 45.5 fold and 5.9% yield. It's molecular weight and pl value were 35 kD by SDS-PAGE and 4.5 by isoelectric focusing, respectively. The enzyme was the most active at pH 5.8. The optimum temperature of the enzyme activity was 50 degrees C. The enzyme was stable at pH 6.0-8.0 and below 50 degrees C. The activity of the enzyme was inhibited by Hg2+, Ag+ strongly. For various substrates, such as locust bean gum, guar gum, sesbania gum and konjac gum, Km and Vmax value of the enzyme were 3.8, 14.9, 11.3, 2.4 mg/mL, and 24.5, 86.5, 38.4, 19.8 mumol.min-1.mg-1, respectively. The enzyme hydrolize various plant beta-mannans, with valuable oligosaccharides and without monosaccharide.