Partial Purification and Characterisation of Cellulase from Sugarcane as affected by postharvest storage of Sugarcane ( Saccharum officinarum L) stem

摘要

This study was aimed at evaluating the effect of storing sugar cane stem at room temperature on the activity of its cellulase enzyme. Cellulase was partially purified and characterised from freshly harvested sugarcane (FHS) and stored sugarcane (SS) (Saccharum officinarum L) using 80% ammonium sulphate precipitation and dialysed; the FHS had 136.52 units/ mg protein while the SS 184.53 units/mg proteins. The Km value of cellulase of SS was 0.09 mg/ml while that of FHS was 0.540 mg/ml. The substrate specificity on different cellulose materials (orange peel, banana peel, maize starch, sugarcane bagasse, maize cob and apple pomace) showed varying results for the two enzyme sources. The enzyme from FHS showed 100% activity with banana peel and sugar cane bagasse while the enzyme from SS showed 100% activity with the peels of orange and banana and sugar cane bagasse. Maize cob and apple pomace as carbon source showed very little cellulase activities, 17.4% for FHS and 26.6% for SS. The optimum pH value of partially purified cellulase of FHS was 4.0 while that of SS was 7.0 and the enzyme was optimally active at 40°C for both sources. At the concentrations of 1.0 mM and 10.0 mM, Ca2+ and Na2+ caused the enzyme activity to increase by 100% residual activity in both FHS and SS. Cellulase of stored sugarcane have increased activity compared with cellulase of freshly harvested sugarcane since it exhibited a very low Km.