Engineering Saccharomyces boulardii for cell surface display of heterologous protein

Abstract Purpose: Saccharomyces boulardii shares >99% similar genome sequences with S. cerevisiae, although there are some different genetic and metabolic elements between the two strains. Much is known about the cell surface display system of S. cerevisiae, but S. boulardii is still lacking. Therefore, in this study, cell surface display of S. boulardii is compared with different anchor proteins. Methods: For visualization of the cell surface display system, six strains expressing the enhanced green fluorescent protein (Egfp) and an anchor protein as a fusion protein were constructed. Then a heterologous protein, endo-inulinase, was expressed with selected anchor proteins through fluorescence intensity comparison. Results: Analysis by fluorescence microscopy revealed that the anchor proteins Cwp2 and Sed1 exhibited the highest fluorescence intensity. Furthermore, expressed selected anchor proteins and heterologous protein, endo-inulinase, the two mutant strains could degrade and consume almost inulin in 48 h. Conclusion: Through the expression of endo-inulinase, we confirmed that not only Egfp but also heterologous protein is well expressed, and successfully built a S. boulardii cell surface display system.