Characterization of a Novel α-amylase from Bacillus m acquariensis Isolated from Cassava Peels Dump Site

In search for hydrolytic enzymes with novel catalytic ability from agricultural waste materials, a moderately thermostable α-amylase from Bacillus macquariensis isolated from cassava peels dumpsite has been purified and characterized. The enzyme was purified in two steps using ion exchange and gel filtration chromatography. The purified enzyme appeared to be a dimer with a native molecular weight estimate of 63.4 ± 1.27 kDa on gel filtration while the subunit molecular weight gave 28.9 kDa. The apparent Km and Vmax of this enzyme for soluble starch were estimated, to be 106.8 ± 10.08 mg/ml and 4380 ± 222 units/mg protein respectively. The enzyme was not readily saturated with gelatinized starch at concentrations as high as 14%. The optima temperature and pH established for amylolytic activity in this study were 55°C and 6.0 respectively while the activation energy for starch hydrolysis (Ea) was 41.5 ± 0.5 kJK -1 . The enzyme retained more than 70% of its maximum activity over a broad range of pH 4.5-9.0 at room temperature for 60 min. This study revealed the purified α-amylase to be an enzyme in which activity and heat stability were not stimulated by an inclusion of exogenous Ca 2+ .