Growth and fermentation patterns of Saccharomyces cerevisiae under different ammonium concentrations and its implications in winemaking industry.
OBJECTIVE
To study the effects of assimilable nitrogen concentration on growth profile and on fermentation kinetics of Saccharomyces cerevisiae.


RESULTS
Saccharomyces cerevisiae was grown in batch in a defined medium with glucose (200 g l(-1)) as the only carbon and energy source, and nitrogen supplied as ammonium sulphate or phosphate forms under different concentrations. The initial nitrogen concentration in the media had no effect on specific growth rates of the yeast strain PYCC 4072. However, fermentation rate and the time required for completion of the alcoholic fermentation were strongly dependent on nitrogen availability. At the stationary phase, the addition of ammonium was effective in increasing cell population, fermentation rate and ethanol.


CONCLUSIONS
The yeast strain required a minimum of 267 mg N l(-1) to attain complete dryness of media, within the time considered for the experiments. Lower levels were enough to support growth, although leading to sluggish or stuck fermentation.


CONCLUSIONS
The findings reported here contribute to elucidate the role of nitrogen on growth and fermentation performance of wine yeast. This information might be useful to the wine industry where excessive addition of nitrogen to prevent sluggish or stuck fermentation might have a negative impact on wine stability and quality.
Centro de Genética e Biotecnologia, Universidade de Trás-os-Montes e Alto Douro, Vila Real, Portugal. afaia@utad.pt
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D000645:Ammonium Sulfate / Q000378:metabolism; D015169:Colony Count, Microbial / Q000379:methods; D003470:Culture Media; D000431:Ethanol / Q000378:metabolism; D005285:Fermentation / Q000502:physiology; D019649:Food Industry; D005516:Food Microbiology; D005947:Glucose / Q000378:metabolism; D009584:Nitrogen / Q000378:metabolism; D010710:Phosphates / Q000378:metabolism; D000644:Quaternary Ammonium Compounds / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000254:growth & development / Q000378:metabolism / Q000502:physiology*; D014920:Wine / Q000382:microbiology*
D003470:Culture Media; D010710:Phosphates; D000644:Quaternary Ammonium Compounds; C024788:ammonium phosphate; D000431:Ethanol; D005947:Glucose; D009584:Nitrogen; D000645:Ammonium Sulfate