Faculty of Biotechnology and Food Sciences in Nitra Journal of Microbiology, Biotechnology and Food Sciences 1338-5178 vol. 5 2016 2016-06-01 2016-06-01 THERMOPHILIC BACILLUS LICHENIFORMIS RBS 5 ISOLATED FROM HOT TUNISIAN SPRING CO-PRODUCING ALKALINE AND THERMOSTABLE α-AMYLASE AND PROTEASE ENZYMES 557 562 EN Rakia Ben Salem Rakia Ben Salem Mohamed Salah Abbassi Mohamed Salah Abbassi Jean-luc Cayol Jean-luc Cayol Amel Bourouis Amel Bourouis Sihem Mahrouki Sihem Mahrouki Marie-Laure Fardeau Marie-Laure Fardeau Omrane Belhadj Omrane Belhadj Bacillus licheniformis RBS 5 was isolated from thermal spring in Tunisia. The isolate coproduce α-amylase and protease enzymes. The α-amylase activity showed an optimal activity at approximately 65°C and in wide pH interval ranging from 4 to 9. This enzyme was stable over the range of 45 to 70°C after 30 min of incubation and in the pH range of 8 to 10. Protease activity was optimal; at 80°C, pH 12. This enzyme was stable until 60°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 Mg 2+) have an inhibition effect on α-amylase. However, protease activity was enhanced by Ca2+, Cu2+ and Mg 2+); 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.
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