INULINASE FROM ASPERGILLUS VERSICOLOR - A POTENT ENZYME FOR PRODUCINGFRUCTOSE FROM INULIN

An alternate procedure for producing fructose syrup is by enzymatic hy drolysis of inulin which is a fructose polymer and is stored as a rese rve carbohydrate in many plants. For achieving the objective of having high inulinase producing organism, various fungal species were screen ed for the production of extracellular inulinase. Aspergillus versicol or (MTCC 280) produced about 14 units of inulinase ml(-1) of medium af ter 15 d of growth. The inulinase was purified by over 50-folds by amm onium sulphate fractionation, DEAE cellulose, CM cellulose and sephade x G 150 column chromatographies. Invertase to inulinase ratio of one i n culture filtrate was reduced to 0.7 in the purified preparation. The pH and temperature optima were 55, and 55 to 60 degrees C, respective ly. The molecular weight of inulinase was determined as 230+/-20Kd. Mi chaelis constant (Km) of inulinase with inulin as substrate was 0.12 m M. The purified preparation produced fructose as the only product from inulin indicating that inulinase has primarily exo mode of action. En zyme was considerably stable to heat and 1h heating at 60 degrees C ca used only 15 to 20 per cent loss of activity, Inulinase from A. versic olor because of its high temperature optima and stability towards heat could hydrolyse inulin at higher temperature with ease and appeared t o be suitable for industrial exploitation. Enzyme was inhibited non-co mpetitively by HgCl2 having dissociation constant of enzyme-inhibitor complex(Ki) of 0.2 mu M.