Studies on the Physicochemical Properties of Amylases Obtained from Digitaria Exilis (White Fonio, Acha) and Digitaria Iburua (Black Fonio, Iburu) Under Optimized Conditions

Abstract

The need for indigenous cereals as a substitute to popular ones such as barley and wheat has necessitated the search for unpopular cereals like fonio. This study investigated the most appropriate conditions for the induction of amylases from acha and iburu using response surface methodology in water which is of traditional practice and water containing phosphate salts (10 mM sodium phosphate buffer, pH6.5). Malted grains as a function of days of germination produced the highest amylolytic activities on second day of germination with 24337 U/mgprotein when steeped in water and 15794 U/mgprotein for iburu steeped in water containing phosphate salt. However, white fonio produced lesser amount of amylases when steeped in water with 17948 U/mgprotein and 12046 U/mgprotein in water containing salt. These were purified using Concanavalin A Sepharose and were further purified on Bio-gel P100 gel filtration technique for a pure homogenate. The physicochemical properties of these homogenates were studied and white fonio was optimum at pH 6.0 while black fonio was pH 6.5. Similarly, both were stable to temperature at above 65^oC. CaCl₂.2H₂O and MnCl₂.4H₂O activated activities of amylases from two grains but NaCl and KCl led to a reduction in activities while CuSO₄ and MnCl₂ absolutely inactivated activities of these enzymes. Physicochemical properties of these amylases are similar to that obtained from other grains, hence fonio can be used to totally replace amylases from other grains and as such promote the utilization of these local grains and as such improve the economy of our nation Nigeria.