New Strains ofBacillus licheniformisandBacillus coagulansproducing Thermostable α‐Amylase Active at Alkaline pH

摘要

Two species ofBacillusproducing thermostable α‐amylase with activity optima at alkaline pH are reported here. These organisms were isolated from soil and have been designated asBacillus licheniformisCUMC 305 andB. coagulansCUMC 512. The enzymes released by these two species were partially purified up to about 81‐ and 72‐fold respectively of the initial activity. The enzyme fromB. licheniformisshowed a wide temperature‐range of activity, with optimum at 91°C. At this temperature it remained stable for 1 h. It retained 40–50 activity at 110°C and showed only 60 of its activity at 30°C. The enzyme showed a broad pH range of activity (4–10) retaining substantial activity on the alkaline side. The optimum pH was 9·5. The enzyme ofB. coagulansshowed activity up to 90°C, with optimum at 85°C and had a wide pH range with optimum at 7·5–8·5. The hydrolysis pattern of the substrate starch by these enzymes indicated that glucose, maltose, maltotriose and maltotetraose are the principal products rather than h