Enhancement of Activity of Carbohydrases with Endo-depolymerase Action in Trichoderma reesei Using Mutagenesis

Abstract

In order to obtain feed enzyme preparations with increased activity of endo-carbohydrases of depolymerase action, mutagenesis of the Trichoderma reesei strain was carried out using ultraviolet and ionizing irradiation. Application of fractionated UV-irradiation made it possible to increase the endoglucanase activity by 20% and xylanase activity by 80% compared to the original strain. The greatest effect was achieved after multistage gamma-irradiation mutagenesis with a cobalt source. When the mutant T. reesei-Co-44 was cultured in shaking flasks, its endoglucanase activity was increased 5-fold, while xylanase activity increased more than 8-fold compared to the original strain. High activity of the target enzymes in the mutant strains was confirmed by the results of fed-batch cultivation in laboratory reactors with lactose feeding as a carbon source and an inducer of cellulases and xylanases biosynthesis. The maximum activity of endoglucanase and xylanase was achieved by culturing strain T. reesei-Co-44 obtained as a result of gamma-irradiation mutagenesis and amounted to 1324.2 ± 70.1 and 3394 ± 164 U/mL, respectively. This activity level makes it possible to produce competitive enzyme preparations of carbohydrases for fodder production.