THERMOPHILIC BACILLUS LICHENIFORMIS RBS 5 ISOLATED FROM HOT TUNISIAN SPRING CO-PRODUCING ALKALINE AND THERMOSTABLE alpha-AMYLASE AND PROTEASE ENZYMES

Bacillus licheniformis RBS 5 was isolated from thermal spring in Tunisia. The isolate coproduce a-amylase and protease enzymes. The alpha-amylase activity showed an optimal activity at approximately 65 degrees C and in wide pH interval ranging from 4 to 9. This enzyme was stable over the range of 45 to 70 degrees C after 30 min of incubation and in the pH range of 8 to 10. Protease activity was optimal; at 80 degrees C, pH 12. This enzyme was stable until 60 degrees C over the pH range of 10 to 12. EDTA at concentration of 5 mM reduces slightly both activities evoking the serine alkaline protease. Cationic ions (Ca2+, Cu2+, Zn2+, and Mg2+) have an inhibition effect on a-amylase. However, protease activity was enhanced by Ca2+, Cu2+ and Mg2+); the other cations reduce slightly the proteolytic activity. SDS and H2O2 were found as inhibitors for both activities whereas Triton X-100 and perfume have no effect. Taken together, these traits make protease activity of B. licheniformis RBS 5 as efficient for use in detergent industry.