Protein expression and enzymatic activity of cellulases produced by Trichoderma reesei Rut C-30 on rice straw

Rice straw after pretreatment was used as the substrate to induce the production of cellulases by a cellulase-producing strain Trichoderma reesei Rut C-30. Compared with concentrated KH2PO4 medium, the medium with low concentration of KH2PO4 could yield higher enzymatic activities for cellulose hydrolysis. The use of alkaline-treated rice straw sticks and non-pretreated rice straw powder as the inducing substrates in batch culture could result in cellulase activities of 1.07 and 0.71 FPU/ml, respectively. These levels are comparable to values reported in the literature on the use of other cellulose sources as the inducers. Results from two-dimensional gel electrophoresis (2-DE) of proteins secreted by the T. reesei strain using trichloroacetic acid (TCA) precipitation were reproducible. Among cellulase components, cellobiohydrolases (CBH) were found to dominate over about 37% of the total extracellular proteins, according to 2-DE gel. The enzymatic activity could be correlated with the protein expression level determined based on the image intensity on the 2-DE gel.