Recent studies have already described the effects of global warming on wine industry (Mira de Orduña, 2010). At the grape level, changes in acidity, phenolic maturation, tannin content and increase in sugar content has been proven to occur, the latter causing increased ethanol levels in the final products. New trends in consumer preferences together with different aspects concerning marketing issues are driving researchers, engineers and oenologists efforts towards exploring different approaches for the reduction of the concentration of this metabolite. Although Saccharomyces cerevisiae is largely recognized as the main player during wine fermentation, strains belonging to different specie s of the genera Hanseniaspora/Kloeckera, Pichia, Candida or Metschnikowia are known to predominate during the first stages of this industrial process. Despite these yeast species are known to contribute to the sensory attributes of the resulting product (Rojas et al. 2003), a detailed description of their metabolism during winemaking in still lacking. In order to reduce the alcoholic content of wines, it would be very interesting to analyze the respiro-fermentative behaviour of these yeasts under winemaking conditions as the utilization of sugars following oxidative pathways would result in the reduction of sugars to be used as substrates by the fermentative metabolism of S. cerevisiae (Gonzalez et al. 2013). For that purpose, using the set-up proposed in this work we have analyzed the aerobic sugar metabolism of different isolates belonging to 20 different yeast species. Experiments have been performed in culture media presenting sugar concentrations similar to those found in natural grape musts. Key physiological parameters such as the respiratory quotients and sugar and ethanol consumption/production rates have been recorded. Special attention has been paid to the production of non-desired secondary metabolites such as acetic acid. The present work sets the basis for the selection of candidate non-Saccharomyces yeast species to be used in a sequential inoculation for the reduction of the eth anol content in winemaking. The proposed strategy would require the implementation of detailed studies focusing on, among other issues, oxygen availability and the implementation of innovative oxygenation strategies during the initial stages of wine fermentation.

Póster presentado en la 5th Conference on Physiology of Yeast and Filamentous Fungi (PYFF5), celebrado en Montpellier del 4 al 7 de junio de 2013.

Peer Reviewed