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

Conversion of lignocellulosic substrates is limited by several factors, in terms of both the enzymes and the substrates. Better understanding of the hydrolysis mechanisms and the factors determining their performance is crucial for commercial lignocelluloses-based processes. Enzymes produced on various carbon sources (Solka Floc 200, lactose and steam-pre-treated corn stover) by Trichoderma reesei Rut C30 were characterised by their enzyme profile and hydrolytic performance. The results showed that there was a clear correlation between the secreted amount of xylanase and mannanase enzymes and that their production was induced by the presence of xylan in the carbon source. Co-secretion of alpha-arabinosidase and alpha-galactosidase was also observed. Secretion of beta-glucosidase was found to be clearly dependent on the composition of the carbon source, and in the case of lactose, 2-fold higher specific activity was observed compared to Solka Floc and steam-pre-treated corn stover. Hydrolysis experiments showed a clear connection between glucan and xylan conversion and highlighted the importance of beta-glucosidase and xylanase activities. When hydrolysis was performed using additional purified beta-glucosidase and xylanase, the addition of beta-glucosidase was found to significantly improve both the xylan and glucan conversion.