|dc.description.abstract||Background: Saccharomyces cerevisiae is the most relevant yeast species conducting the alcoholic fermentation
that takes place during winemaking. Although the physiology of this model organism has been extensively studied,
systematic quantitative physiology studies of this yeast under winemaking conditions are still scarce, thus limiting
the understanding of fermentative metabolism of wine yeast strains and the systematic description, modelling and
prediction of fermentation processes. In this study, we implemented and validated the use of chemostat cultures as
a tool to simulate different stages of a standard wine fermentation, thereby allowing to implement metabolic flux
analyses describing the sequence of metabolic states of S. cerevisae along the wine fermentation.
Results: Chemostat cultures mimicking the different stages of standard wine fermentations of S. cerevisiae EC1118
were performed using a synthetic must and strict anaerobic conditions. The simulated stages corresponded to the
onset of the exponential growth phase, late exponential growth phase and cells just entering stationary phase, at
dilution rates of 0.27, 0.04, 0.007 h−1
, respectively. Notably, measured substrate uptake and product formation rates
at each steady state condition were generally within the range of corresponding conversion rates estimated during
the different batch fermentation stages.
Moreover, chemostat data were further used for metabolic flux analysis, where biomass composition data for each
condition was considered in the stoichiometric model. Metabolic flux distributions were coherent with previous
analyses based on batch cultivations data and the pseudo-steady state assumption.
Conclusions: Steady state conditions obtained in chemostat cultures reflect the environmental conditions and
physiological states of S. cerevisiae corresponding to the different growth stages of a typical batch wine
fermentation, thereby showing the potential of this experimental approach to systematically study the effect of
environmental relevant factors such as temperature, sugar concentration, C/N ratio or (micro) oxygenation on the
fermentative metabolism of wine yeast strains.||es_ES