Evaluation of combination treatments of sodium hydroxide and steam explosion for the production of cellulase-systems by two T-reesei mutants under solid-state fermentation conditions

A central composite orthogonal design model was used to optimize pretreatme nt and culture conditions for the production of cellulase-systems by T. ree sei QMY-1 and MCG 80 using wheat straw as carbon source. The model was capa ble of predicting conditions for maximum filter paper activity (FPA) and be ta-glucosidase activity (beta GA). Statistical analysis showed close agreem ent between the experimental FPA and beta GA activities and predicted value s. Maximum FPA of 9.88 IU/ml and 8.38 IU/ml were obtained for T. reesei MCG 80 and T. reesei QMY-1, respectively, using 4% NaOH pretreatment and initi al culture pH 6, under solid-state fermentation conditions. The cellulase-s ystems produced were capable of hydrolyzing over 80% delignified wheat stra w. Combination of NaOH pretreatment with steam explosion did not enhance th e activity of the cellulase-systems of the two mutants. (C) 2000 Elsevier S cience Ltd. All rights reserved.