A new thermophilic inulinase-producing strain, which grows optimally at 60 
degrees C, was isolated from soil samples with medium containing inulin as a 
sole carbon source. It was identified as a Bacillus smithii by analysis of 16s 
rDNA. Maximum inulinase yield of 135.2 IU/ml was achieved with medium pH7.0, 
containing inulin 2.0%, (NH(4))H(2)PO(4) 0.5%, yeast extract 0.5%, at 50 degrees 
C 200 rpm shaker for 72-h incubation. The purified inulinase from the 
extracellular extract of B. smithii T7 shows endoinulinolytic activity. The 
optimum pH for this endoinulinase is 4.5 and stable at pH range of 4.0-8.0. The 
optimum temperature for enzyme activity was 70 degrees C, the half life of the 
endoinulinase is 9 h and 2.5 h at 70 degrees C and 80 degrees C respectively. 
Comparatively lower Michaelis-Menten constant (4.17 mM) and higher maximum 
reaction velocity (833 IU/mg protein) demonstrate the endoinulinase's greater 
affinity for inulin substrate. These findings are significant for its potential 
industrial application.