Purification and some properties of glucose isomerase from Bacillus megaterium

The objective of this study is to produce and purify glucose isomerase (GI) from Bacillus megaterium and to determine some of its properties. Soil sample was collected from cassava starch processing site and used immediately for bacterial isolation. Selected isolate produced the best GI activity in a preliminary test. The isolate was grown in media containing various carbon, nitrogen and metal salts for enzyme production. Among the carbon sources tested, Galactose gave the best yield (1.1 U/mg protein). Peptone was the best nitrogen source and caused the production of 0.85 U/mg protein. Of the tested metal salts, MgSO4.7H2O caused the production of the best enzyme activity of 0.81 U/mg protein. The GI was purified by precipitation with (NH4)2SO4 and chromatography on diethyl amino-ethyl (DEAE) – cellulose and DEAE-sephadex G-200 column. Thereafter, the enzyme activity was determined with the optimum temperature and pH at 40oC and 6.0 respectively. The enzyme was also characterized with a molecular weight of 65kDa as determined by the SDS – PAGE analysis. The enzyme could be applied in the production of high fructose corn syrup.

 E. D. Nwede, O. Nwokoro