S. cerevisiae transcriptional response to the presence of a competing yeast in wine fermentation.
Oreto Antúnez, José E. Pérez-Ortín
Bioquímica y Biología Molecula, Universitat de València, Dr. Moliner 50, Burjassot, E46100, Spain
S. cerevisiae has become universally accepted as the principal wine yeast, although it is well established that wine fermentations are not the action of a single yeast species. Rather, the final product results from the combined action of several yeast and bacterial species. The non- Saccharomyces yeasts grow well during the early stages of fermentation, when ethanol concentration is low, being later replaced by Saccharomyces strains, which are more tolerant to ethanol and more proficient for growth in high sugar media. The chemical changes produced by non- Saccharomyces affect both the growth kinetics and the metabolism of S. cerevisiae. Population dynamics of yeasts has been widely studied, but little is known about interactions between yeast species. To address this topic we inoculated in synthetic must a S. cerevisiae wine strain (T73) in single and mixed cultures with a wine strain of Kluyveromyces thermotolerans. Then, we compared the behaviour of mixed cultures versus single cultures of T73 and we conclude that the Kluyveromyces presence causes T73 to grow better and a to increase ethanol production. The analysis of the transcriptomes using DNA macroarrays made with S. cerevisiae probes shows that the presence of another yeast provokes an extensive differential response in early stages of fermentation in S. cerevisiae.