Partial purification and some physicochemical properties of Aspergillus flavus -amylase isolated from decomposing cassava peels

摘要

α-Amylase is one of the most important enzymes of great significance due to its wide area of potential application in food, fermentation, textile, paper, detergent and pharmaceutical industries. This study aimed at production of α-amylase from an indigenous fungal source and also ascertaining the properties of the enzyme for maximal activity. The enzyme was isolated from decomposing cassava peels, fractionated at 70% ammonium sulphate and characterized. The fungal isolate was characterized as Aspergillus flavus. The crude enzyme extract had a specific activity of 2.40 Umg-1 which increased to 7.88 Umg-1 on fractionation with ammonium sulphate with a yield of 11.10% and purification fold of 3.28. The Km and Vmax values of 0.52±0.009 g/dL and 62.57±0.23 U/min were obtained, respectively, at 2% cassava starch substrate. The enzyme also demonstrated maximum activity at 70°C and pH 5.0. It thus produces α-amylase which is thermostable, a property which could be exploited for industrial purposes where hydrolysis of starch and other complex carbohydrates are required.