Optimisation of industrial strains of Saccharomyces cerevisiae using recombinant and non-recombinant methods

The production of fermented beverages such as beer and wine is typically achieved using strains of Saccharomyces cerevisiae, which have been selected for their reliable fermentative properties and desirable sensory contribution to the end product. Even so, these strains are not without shortcomings and new strains are constantly being sought. In aiming to provide such strains, working with industrial isolates has its own set of challenges. Wine strains of S. cerevisiae are typically of higher ploidy or aneuploid, frequently lack convenient selectable markers and are homothallic. Laboratory strains, along with their comprehensive set of genetic tools, might be a more convenient research vehicle, but the fact remains that such strains fare poorly under the highly stressful conditions of industrial fermentations: sugar contents of over 200 g/L; low nutrient availability and pH; and high final ethanol concentrations. More importantly, the wines produced by laboratory strains of yeast frequently display poor sensory properties. Put simply, laboratory yeast lack the desirable phenotypic characteristics needed to make wine of quality to enable industrially relevant studies.