β-Glucosidase Production by <I>Trichoderma reesei</I>

Abstract

The hydrolysis of cellulose to the water-soluble products cellobiose and glucose is achieved via synergistic action of cellulolytic proteins. The three types of enzymes involved in this process are endoglucanases, cellobiohydrolases, and beta-glucosidases. One of the best fungal cellulase producers is Trichoderma reesei RUT C30. However, the amount of beta-glucosidases secreted by this fungus is insufficient for effective cellulose conversion. We investigated the production of cellulases and beta-glucosidases in shake-flask cultures by applying three pH-controlling strategies: the pH of the production medium was adjusted to 5.8 after the addition of seed culture with no additional pH adjustment performed, the pH was adjusted to 6.0 daily, and the pH was maintained at 6.0 by the addition of Tris-maleate buffer to the growth medium. Different carbon sources Solka Floc 200, glucose, lactose, and sorbitol were added to standard Mandels nutrients. The lowest beta-glucosidase activities were obtained when no pH adjustment was done regardless of the carbon source employed. Somewhat higher levels of beta- glucosidase were measured in the culture filtrates when daily pH adjustment was carried out. The effect of buffering the culture medium on beta-glucosidase liberation was most prominent when a carbon source inducing the production of other cellulases was applied.

Influence of buffer systems on Trichoderma reesei Rut C-30 morphology and cellulase production

“…The maximum filter paper activity value was obtained when the concentration of buffer arise to 100 mM. In contrast, citrate buffered culture presented the inverse trend, the higher citrate buffer concentration the lower the filter paper activity, which is in accordance with Juhász et al (2005), who tested different Tris-maleate buffer concentrations and shows that the higher the buffer concentration the lower the filter paper activity at day 5 of cultivation. In the present work, it was observed that the influence of buffer concentration in filter paper activity is depending on the buffer used for medium supplementation.…”

“…T. reesei produces an extracellular, stable, and efficient cellulase enzyme system (Tengborg et al 2001;Lynd et al 2002). T. reesei Rut C-30 is a partially catabolite derepressed, hypercellulolytic mutant strain, widely studied, with improved enzyme production capabilities, when compared to the wild-type and some other strains (Xiong et al 2004;Juhász et al 2005).…”

“…Medium supplementation, with 100 mM succinate buffer, at pH 4.8, leads to the highest β-glucosidase activity (0.4 UI/mL), what is considerably higher when compared with control (medium without buffer), which did not presented β-glucosidase activity. Juhász et al (2005) had also investigated the production of cellulases and β-glucosidases in shake-flask cultures by applying different pH-controlling strategies and different carbon sources and they also obtained the lowest β-glucosidase activities without pH adjustment.…”

Characterisation of Specific Activities and Hydrolytic Properties of Cell-Wall-Degrading Enzymes Produced by Trichoderma reesei Rut C30 on Different Carbon Sources

“…To maintain a constant pH (5.8) in the flasks, a 0.1 M Tris base-maleic acid buffer system was applied [1,22]. After inoculation, the flasks were incubated for 8 days at 28°C and 250 rpm.…”

On-site integrated production of cellulases and β-glucosidases by Trichoderma reesei Rut C30 using steam-pretreated sugarcane bagasse

“…However, it has also been reported that the amount of β-glucosidase in the culture filtrate of T. reesei Rut C30 may depend on the pH of the culture [37][38][39][40]. In this work, it was possible to obtain enzyme pools with rather significant β-glucosidase content, up to 0.62 IU/mL, in buffered medium containing lactose with an initial pH of 6.0 and a final pH of 5.8.…”