Purification and Some Properties of aThermostable Glucose-Producing α-Amylase from Bacillus sp. Cos.

Opurum C.C, Odibo F.J.C

Thermophilic microorganisms are known for their high temperature requirement. One outstanding attribute of these organisms is the production of thermostable enzymes, and because of this feature, enzymes produced by thermophiles have found a number of commercial and research applications. Thus there is a continuous search for thermophilic micro-organisms capable of producing thermostable enzymes with novel characteristics. In the present study, a thermostable α-amylase-producing bacterial strain was isolated from soil. The isolate was phenotypically identified as Bacillus sp. Cos by adopting standard methods and was used in the production of amylase in sub-merged shake flask culture. The enzyme was purified 8-fold by cold acetone (-10OC) precipitation, ion-exchange chromatography on DEAE -Sephadex (A-50) and on Bio-gel P-4 gel filtration column. The homogeneity and molecular weight was estimated to be 38.02KDa by SDS-PAGE. The enzyme was optimally active at 70OC and pH7.0. It was not activated by any of the tested metal ions but was strongly inhibited by Hg2+. The enzyme hydrolyzed some tested polysaccharides producing only glucose. The Km values (mg/ml) for glycogen, starch, amylopectin, pullulan and amylose were 0.71, 0.83, 0.83, 1.67 and 10.0, respectively. The production of only glucose from various polysaccharides by Bacillus sp. Cos thermostable α-amylase, its optimum pH and temperature of activity at 7.0 and 70OC, coupled with its independence on metal ions for activation and stabilization suggests its applicability in starch saccharification for industrial production of glucose and fructose syrups.