Production and characterization of cellulolytic enzymes from the thermophilic fungus Thermoascus aurantiacus under solid state cultivation of agricultural wastes

Abstract

Extracellular cellulolytic enzymes were produced under solid state cultivation by the thermophilic fungus Thermoascus aurantiacus and characterized. Elevated levels of endoglucanase and β-glucosidase activities were produced simultaneously by optimization of growth factors. Under optimal growth conditions, 1572 U endoglucanase and 101.6 U β-glucosidase per g of carbon source were obtained. Chromogenic (fluorogenic) 4-methylumbelliferyl-β-glycosides of glucose (MUG) and cellobiose (MUG2) were used to characterize the cellulolytic multienzyme components after separation by isoelectric focusing. The zymogram indicated one endoglucanase and one β-glucosidase with pI values 3.5 and 3.9, respectively. Both enzymes exhibited significant thermostability, with half-lives of 42 and 18 min, respectively, at 80 °C.