7-67: Yeast surface display for heterogeneous enzymatic catalysis

A whole-cell biocatalyst based on a recombinant strain of Saccharomyces cerevisiae has been developed. Enzymes that are active extracellularly can be displayed on the yeast cell surface, allowing the cell to be used as an inexpensive heterogeneous catalyst. Lipases can convert waste glycerol from biodiesel to glycerol carbonate, a value-added derivative. A platform for display of enzymes (e.g., lipases) on the surface of S. cerevisiae has been constructed based on an endogenous flocculation protein, FLO1. Fusion proteins were created by ligating the flo1 gene to two lipases and enhanced green fluorescent protein (eGFP). The fusion proteins were cloned into a system of complementary shuttle vectors. The proteins’ relative production levels are regulated by nutritional requirements through variants of the GAL and MET promoters. Surface display of eGFP was examined by flow cytometry. Activity of surface-displayed lipase was measured in spectrophotometic assays and batch reactions.