PRODUCTION, PURIFICATION AND CHARACTERIZATION OF α-Amylase OF Aspergillus sydowii IMI 502692

There is a high demand for amylase because of the low price and abundance of the starch feedstock from which bio-ethanol, food and chemicals can be produced. However, the cost and efficiency of amylase cocktails remain a significant bottleneck to the availability of amylase to meet the high industrial demand to sustain the economically competitive production processes. The method employed in enzyme production is largely responsible for the high cost of the enzymes. There is a dare need to produce low cost and efficient α-amylase. The use of agricultural waste is a good approach to producing low-cost amylase. α-Amylase was produced by Aspergillus sydowii IMI 502692 using Solid State Fermentation of cassava root fibre (5 g) buffered with (% w/v): CaCl2.2H2O, 0.05 g; (NH4)2SO4, 1 g; KH2PO4, 0.3 g; MgSO4.7H2O, 0.05 g; cow blood meal, 0.3 g; Tween 20, 0.5% (v/v), 5 mM Mn2+ and 100 ml deionized water. Time-course of α-amylase production by A. sydowii IMI 502692 revealed a single peak of α-amylase activity (1.327U ml-1) and biomass production (0.327 g) at day 2 with a corresponding culture pH of 3.620. Supernatant fluid, 125 ml 20 mM phosphate buffer extract, from the culture, was concentrated by dialysis (4.5 by 50 cm bag) against changes of 5M sucrose solution until 5.6 folds concentrations were achieved. The dialysate partially purified through ion-exchange chromatography on DEAE Sepharose and gel filtration on Sephadex G-200 shows a single protein band with the amylolytic activity which gave 4.38% retention of overall activity with 3.16 folds purification. There was a 3.45 folds recovery of dialysate with 2.79% yield relative to the total activity. Optimal activity and stability retained 100% of the original activity for 1 h and also retained above 47% activity at 61ºC for 1 h. α-Amylase optimal pH activity was at 6.0 and stable at pH 3 to 7 for 1 h with more than 70% activity retention. Sr2+, Fe2+, Mn2+ and Ni2+ inhibited the activity of α-amylase from A. sydowii IMI 502690 while Cu2+, Zn2+ and Ca2+ induced its activity.