The relative glucose uptake abilities of non-Saccharomyces yeasts play a role in their coexistence with Saccharomyces cerevisiae in mixed cultures.

The growth and glucose uptake of single cultures of the wine-related yeasts Kluyveromyces thermotolerans, Torulaspora delbrueckii, and Saccharomyces cerevisiae were investigated. The yeasts had different specific glucose uptake rates (qs) that depended on the residual glucose concentration and the oxygen availability. In mixed cultures, the qs values of the yeasts were not subject to any interaction effects over a wide range of glucose concentrations. Our results strongly indicate that the relative glucose uptake abilities of both non-Saccharomyces yeasts, i.e. the qs(non-Saccharomyces)/qs(S. cerevisiae) ratios, regulated their abilities to compete for space in mixed cultures with S. cerevisiae, which, in turn, regulated their early deaths. This hypothesis enabled us to explain why K. thermotolerans was less able than T. delbrueckii to coexist with S. cerevisiae in mixed cultures. Furthermore, it enabled us to explain why oxygen increased the abilities of K. thermotolerans and T. delbrueckii to coexist with S. cerevisiae in the mixed cultures. Copyright 2003 Springer-Verlag