초록
<P>The production of extracellular amylase was investigated employing our laboratory isolate, <I>Aspergillus niger</I> sp. MK 07 and effect of process variables on enzyme production, was studied in a fermentor. It was found that amylase production was maximum when the fermentor volume was maintained at 70%, rate of agitation at 250 rpm, air supply at 2.5 vvm, inoculum concentration of 10%, and a pH of 5.0. Highest enzyme production obtained under all optimized conditions was 1734 U/mL with sucrose as carbon substrate and corn steep liquor as nitrogen source. Enzyme purification studies by ammonium sulphate precipitation and Sephadex G-100 chromatography was evaluated for obtaining purified enzyme. Thermostability of amylase were evaluated with varying concentrations from 0.2 to 0.5 M concentrations of calcium chloride and the highest activity obtained was 3115 U/mL with 0.3 M calcium chloride at 55°C. Effect of temperature and pH on the activity of purified enzyme was evaluated and the purified enzyme showed an activity till 75°C and a pH of 6.5. Application potential of partially purified alpha amylase on desizing of cotton cloth was evaluated with varying enzyme concentrations from 50 to 500 U/mL and the highest desizing activity was found to be at 300 U/mL.</P>