Asian Journal of Microbiology, Biotechnology & Environmental Sciences Paper

A NOVEL THERMOSTABLE A-AMYLASE FROM THERMOPHILIC BACILLUS SE SN-1 AND ITS APPLICATION IN THE LIQUEFACTION OF SORGHUM STARCH FOR ETHANOL FERMENTATION

NILAY DEV, RAMAN SONI2 AND S.K. SONI

Abstract

A new strain of Bacillus sp. SN-1, isolated from hot spring waters, was capable of producing significant levels of a-amylase in shake cultures after 48 hours of incubation at 50°C, pH 6.5, in presence of soluble starch (1%), soyabean meal (0.5%) and CaCl2. 2H20 (20 mM). The kinetic studies of partially purified enzyme exhibited the maximum activity at 60°C, pH 6.5 and revealed a high thermostability, retaining more than 90% residual activity at 60°C even after 6 h. The half lives of this enzyme were 2.5 h and 1.5 h at 70°C and 80°C even after 6 h. The half lives of this enzyme were 2.5 h and 1.5 h at 70 ° and 80°C respectively which got further improved with the supplementation of CaC12.2H20. The enzyme preparation competed well with the commercial thermostable a-amylase preparations, Termamylm and BANim, during the hydrolysis of sorghum starch for the production of alcohol and yielded comparable results.