Characterization of a thermostable Bacillus subtilis β-amylase isolated from decomposing peels of Cassava (Manihot esculenta)

Abstract

&#946-Amylase (á-1, 4 glucan maltohydrolase; E.C:3.2.1.2) is used in the food processing, brewing and distilling industries due to its capacity to produce maltose syrup from starch. Here, we report the purification and characterization of â-amylase from Bacillus subtilis isolated from cassava peel waste obtained from a milling factory in Ikenne-Remo, Ogun State, Nigeria. The enzyme was extracted, fractionated at 90% (NH4)2SO4 and further purified using DEAE-cellulose ion exchange chromatography. The molecular weight of the purified enzyme was estimated to be 34.67 Kd. The specific activity of the partially purified enzyme was approximately 1.35 units per mg of protein (Umg-1), Kinetic analysis of its starch hydrolysis activity gave a Km value of 2.496 ± 0.025% and a Vmax of 1.136 ± 0.055 units min-1. The optimum pH and temperature were determined to be 5.5 and 70 0C respectively, and the thermal stability curve gave a maximum activity of 9.75 U at 70oC for 60 min of incubation. Bacillus subtilis â-amylase is valuable for maltose production, which can be hydrolyzed further by other groups of amylase for the production of high cassava glucose syrup used as sweeteners in the food industry.