The endo-β-glucanase III gene (eg3 was obtained from the total RNA of Trichoderma viride AS3.3711 by RTPCR. Sequence analysis indicated that this eg3 gene was composed of 1 257 nucleotides

coding for 418 amino acid residues

and had its own signal peptide. The sequence homologies between this gene with Trichoderma Reesei eg3 were 99.6%. Then it was cloned into the high-copy integrative expression vector pScIKP

generating a recombinant plasmid named pScIKP-eg3

which was then transformed by electroporation into Saccharomyces cerevisiae AS2.489 after linearization. Transformants were detected by SDS-PAGE analysis

Congo Red method and enzyme activity assay. The results showed that transformants could secrete recombinant EG III and produced hydrolysis halos on the Congo-Red-CMC plate

indicating that this eg3 gene was correctly expressed in S. cerevisiae.The highest enzyme activity of recombinant EG III reached 120 U/mL after 60 h cultivation

and the optimum temperature and pH were 60 ℃ and 6.0 respectively. The genetic stability of transformants achieved 99.17% after 50 generations in nonselective medium. In conclusion

the eg3 gene of T. viride could be expressed in industrial yeast strain stably and efficiently.