Protein Expression in Trichoderma reesei
T. ressei is a mesophilic filamentous fungus that synthesizes and secretes cellulase. Its hypersecreting mutant RUT-C30 has become one of the most widely used strains of filamentous fungi for the production of cellulase and recombinant protein. Cellulase production reached over 100 g per liter in high cell density fermentation at commercial scale. Efficient genetic engineering tools and methodologies have been well established for heterologous protein expression. T. reesei grows in simple and cheap medium. Efficient secretion of target protein into the medium provides an opportunity for low-cost downstream processing. High level expression of therapeutic protein has been reported, such as insulin-like growth factor fusion protein at 19 g/L. Several enzymes produced in T. reesei have obtained the GRAS (generally recognized as safe) status from U.S. FDA.
BTR observed high expression and efficient secretion of heterologous proteins as functional enzyme using the promoter and secretion signal peptide from the cellobiohydrolase I gene (cbh1) and an non-antibiotic selection marker. Insertion of a proteolytic cleavage site between the target protein and its fusion partner allowed efficient in vivo processing of fusion protein to release the target protein. High-level protein production was demonstrated in fed batch fermentation at 14-liter scale. More information can be found in the PowerPoint slideshow BTR Trichoderma Protein Production System (pdf).
Information on protein expression in other hosts can be found in PowerPoint slideshows BTR multiple host systems for protein expression (pdf) and Protein expression examples (pdf).