Determination of kinetic parameters of ∝-amylase producing thermophile Bacillus sphaericus

Studies on the -amylase-producing thermophilic bacterium isolated and identified from a hot spring in Jordan and designated as Bacillus sphaericus were carried out in a laboratory scale fermenter. The growth and enzyme production optimum conditions were pH 7 and 50oC. The kinetic study of cellular growth indicates max, Ks, d, Yx/s and kd were 0.53 h-1, 1.1 g/l, 1.98 h, 0.44 g cell/g starch and 0.4 g/l/h, respectively. The optimum starch concentration for the enzyme production was 32 g/l and higher concentrations show substrate inhibition with inhibition constant Ki 190 mg/l. The kinetic parameters of -amylase activation Vmax, and Km were 263 mole mg-1 enzyme min-1 and 0.97 mg/ml, respectively. The effect of different carbon and nitrogen sources on the cellular growth was tested.