CO-production of thermostable, calcium-independent α- amylase and alkali-metallo protease from newly isolated bacillus licheniformis DV3

Abstract

Extracellular thermostable α-amylase and protease from one fermentation of a newly isolated thermophilic Bacillus licheniformis DV3 was studied. The optimum pH and temperature for the enzyme activity were 7.0 and 70°C for the α-amylase, while it was 10.0 and 50°C, respectively for the protease activity. Different carbon and nitrogen sources were investigated for the first time in terms of their effect on the co-production of extracellular thermostable α- amylase and protease. Among carbon and nitrogen sources, soluble starch and urea increased both α-amylase and protease production to a great extend. The α-amylase activity was enhanced in the presence of Mn²⁺, inhibition was obtained in the presence of Ca²⁺and Cu², and it was strongly inhibited by Hg²⁺. The protease activity was increase in the presence of Ca²⁺ and Zn²⁺, whereas the activity was decreased by Mn²⁺and Hg²⁺, and the activity inhibited by EDTA and PMSF.