Cloning of the Endoglucanase cDNA Genes from Trichoderma viride and Their Expression in Saccharomyces cerevisiae

The cellulase genes from Trichoderma viride AS3.3711 were induced with L-sorbose.Its total RNA was extracted.The cDNA was obtained by reverse transcription.The cDNA genes encoding endoglucanases Ⅰ and Ⅲ were isolated by PCR,and then they were cloned into a yeast vector to construct the cellulases-producing Saccharomyces cerevisiae engineering strains. Recombinant yeast strains can secret EGsⅠ and Ⅲ by the guide of the signal peptide themselves.So the expressions of EGⅠ and EGⅢ can be screened by activity plate assays with Congo Red method respectively.The endoglucanase activity was assayed with CMC-Na as a substrate.The results showed that the enzyme activities of EGⅠand EGⅢ culminated at 0.08 U/ml and 0.03 U/ml respectively when they were induced for 70h and 60h respectively.