Extracellular Dextran-inducedp-Nitrophenyl-α-D-glucoside-hydrolyzing Enzyme ofBacillus circulansKA-304: A Producer ofSchizophyllum commune-lytic Enzyme

p-NP-alpha-D-Glucoside-hydrolyzing activity in the culture filtrate of Bacillus circulans KA-304, a producer of Schizophyllum commune cell-wall lytic enzyme, increased remarkably when the bacterium was grown on dextran as a carbon source. It was suggested that the increase of the activity was caused by increases of two major species, alpha-D-glucosidase I and alpha-D-glucosidase II. alpha-D-Glucosidase I, which showed a certain reactivity toward dextran, was isolated from the filtrate (MW 70 kDa, 35-fold, 10% recovery). The enzyme was stable around pH 6.5-7.5 and showed its highest activity at pH 6.5. The enzyme preparation inactivated with p-chloromerucuribenzoic acid recovered its activity by incubating with ditiothereitol. Its substrate specificity suggested that the enzyme was an exo-type enzyme with certain affinity toward alpha-1,6-glucosidic linkage.