GENERAL-CHARACTERISTICS OF THERMOSTABLE AMYLOPULLULANASES AND AMYLASES FROM THE ALKALOPHILIC BACILLUS SP TS-23

An alkalophilic strain of Bacillus sp., designated TS-23, was isolated from a soil sample collected at a hot spring (Tainan, Taiwan). During growth in a medium containing 1% soluble starch as the sole source of carbon, the fermentation broth exhibited both pullulanase and amylase activity. Pullulanase and amylase activities were maximal at 65 degre es C. The pH optima were 8.8 to 9.6 for pullulanase and 7.5 to 9.4 for amylase. Under optimal conditions, a crude preparation hydrolysed pul lulan, generating maltotriose as the major product. Strain TS-23 was f ound to produce five amylases (A(c), A(1), A(2), AP(1), and AP(2)), wh ich were visualized by activity staining of proteins that had been sep arated by native polyacrylamide gel electrophoresis. Both AP(1) and AP (2) had pullulanase activity and A(c), A(1) and A(2) had the ability t o adsorb to raw corn-starch. Native corn-starch was partially digested by adsorbed amylases during the course of 12 h at 50 degrees C, with initiation of granular pitting. Further incubation of the reaction mix ture resulted in considerable morphological changes in cornstarch gran ules, and the main soluble products were maltose, maltotriose and high er oligosaccharides.