Production of acetyl xylan esterase by Trichoderma reesei and Schizophyllum commune

Abstract

Activity of acetyl xylan esterase, an enzyme that removes acetyl groups from acetyl xylan, was coproduced with that of endoxylanase and endoglucanase in two Trichoderma reesei strains and one Schizophyllum commune strain. The levels of activity of extracellular enzymes were measured during the course of cultivation on different carbon sources. The highest activity levels of acetyl xylan esterase were produced by T. reesei QM 9414 in a xylan plus cellulose medium and by S. commune in a cellulose medium. Both strains produced low levels of acetyl xylan esterase activity in glucose, xylose, and cellobiose media. Schizophyllum commune also produced low levels of acetyl xylan esterase activity in xylan and acetyl xylan media. Trichoderma reesei RUT C-30 behaved like a catabolite repression resistant mutant and produced higher enzyme levels than the QM 9414 strain on all carbon sources examined. Analytical gel electrophoresis and isoelectric focusing demonstrated that the acetyl xylan esterase activity of S. commune was represented as one major form (pI 3.4) which also hydrolyzed 4-methylumbelliferyl acetate. The esterase systems of T. reesei strains were found to be more complex than those of S. commune. The pattern of coproduction of the various activities suggested that acetyl xylan esterase is a component of the cellulolytic system of the fungi tested.