Production of Extracellular Amylase by Bacillus thuringiensis subsp. kurstaki HD-1 and its Characteristics

Bacillus thuringiensis subsp. kurstaki HD-1의 아밀라제 생산과 특성 연구

The extracellular amylase production by Bacillus thuringiensis subsp. kurstaki HD-l in amylase production media and its characteristics were investigated. The amylase production was highest in the medium composed of 0.2% soluble starch, 1.0% Bacto-peptone, 0.3% beef extract, 0.3% yeast extract, 0.5% NaCl, 0.3% $K_2HPO_4$, 0.1% $KH_2PO_4$, 0.012% $CaCl_2$.$2H_2O$, 0.005% $MnSO_4$.$H_2O$, and 0.03% $MgSO_4$.$7H_2O$. The amylase activity was inhibited by 50mM EDT A. The enzyme was optimally active from pH 6.5 to 7.0 at $55^{\circ}C$, The specific activity of the enzyme in the ethanol precipitate was 2.01 units/mg, and the Km value was approxi-mately 0.8 mg/ml.

B. thuringiensis subsp. kurstaki HD-1을 아밀라제 생산배지에 $32^{\circ}C$로 24시간 배양하였을 때 아밀라제 활성은 0.40 units/ml 였고, 50mM EDTA에 의하여 활성이 억제되었으며, 기본배지에 soluble starch와 $Ca^{2+}$, $Mg^{2+}$, $Mn^{2+}$을 첨가했을 때 활성이 비교적 높았고, pH6.5와 7.0 사이에서, 온도 $55^{\circ}C$에서 비교적 활성이 높았다. 아밀라제 생산을 위한 최적 배지로는 0.2% soluble starch, 1.0% bacto-peptone, 0.3% beef extract, 0.5% NaCl, 0.3% $K_{2-}$$KH_{2}PO_{4}$, 0.012% CaCl.$2H_{2}O$, 0.005% $MnSO_{4}$.$H_{2}O$, 0.03% $MgSO_{4}$.$7H_{2}O$이었다. 효소 용액을 에 $HPO_{4}$, 0.1% 탄올 침전시켜 5ml의 0.1M 인산염 완충액에 용해한 용액의 비활성은 2.01 units/mg였고, starch에 대한 효소의 Km 값은 0.80 mg/ml였다.