Isolation and properties of extracellular cellulase-hemicellulase complex of Phoma hibernica

Abstract

A cellulase-hemicellulase complex was obtained from the culture supernatant of Phoma hibernica. It was purified by ammonium sulfate precipitation, column chromatography on diethylaminoethyl-Sephadex A-50 and Sephadex G-100. The preparation was capable of degrading carboxymethyl-cellulose, insoluble cellulose, xylan, galacto-, gluco-, and galactogluco-mannan. The distinct protein band obtained after isoelectrofocusing also showed activities towards these substrates. Optimum pH for cellulase and galactomannase activities was 4.5 and for xylanase activity 4.5–5.5. Tetranitromethane, urea and Fe³⁺ inhibited all the enzymatic activities of the complex. The preparation attacked carbohydrate polymers in different manners depending on the substrate. Cellulose was attacked in an exo-wise, xylan in an endowise manner. Nitrophenyl derivatives of carbohydrates were hydrolyzed slowly. It is suggested that the purified enzyme preparation is a complex most probably composed of subunits of different enzymatic activities.