Enzymatic hydrolysis of oil palm biomass for fermentable sugar using polyethylene glycol immobilized cellulase

Abstract

In this work, enzymatic hydrolysis using cellulase both in solution and immobilized form was studied to convert lignocellulosic biomass from empty fruit bunch into fermentable sugars. The cellulase was covalently immobilized with activated and functionalized polyethylene glycol via glutaraldehyde coupling. To determine sample enzyme activity, the equivalent reducing sugars released during hydrolysis reaction with free cellulase and immobilized cellulase respectively, were quantified using 3,5- dinitrosalicylic acid (DNS) method. As a whole, the immobilized cellulase displayed 50% higher efficiency over free cellulase, in reducing sugar recovery during hydrolysis reactions. From the kinetic study, it showed that Michaelis constant (Km) and limiting velocity(Vm«) of immobilized cellulase were 179.2 mg/ml and 33.5mg/ml.min respectively, whereas that of free cellulase were 171.8mg/ml and 34.5mg/ml.min respectively. The higher Km value of immobilized cellulase could be attributed to the polyethylene glycol interference with the binding of cellulase to expose substrate, and enables free interaction of cellulase to hydrolyse cellulose maximally.