Yeasts of genus Brettanomyces and Dekkera have detrimental effects on the organoleptic characteristics of wine. In order to understand their capacity to survive to the stressful environment of wine, physiological studies with the yeasts Brettanomyces bruxellensis ISA 1792, Dekkera anomala IGC 5153 and Saccharomyces cerevisiae IGC 4072 were performed. Yeast ability to tolerate ethanol as sole carbon and energy source or glucose in alcoholic media was investigated. Yeast specific growth rate with ethanol as growth-limiting substrate was assessed in synthetic medium with ethanol as the sole carbon source at concentration ranging from 0.01 to 9% (v/v). Ethanol-enhance cell death and effect of ethanol on yeast growth on glucose were evaluated. In order to assess yeasts cells sugar transport, assays were performed as well. This latter trial was performed with cells previously grown in mineral medium with 2% glucose transferred at midexponential phase in synthetic medium containing different concentrations of alcohol. On average, with low ethanol concentrations S. cerevisiae exhibited higher specific growth than B. bruxellensis, while this latter as well as D. anomala displayed a higher growth capacity with high ethanol levels. B. bruxellensis showed lower sensitivity to ethanol toxic effects than Saccharomyces c. when glucose was used as the sole carbon and energy source. Data from transport assays showed that both yeasts seem to adapt glucose transport mechanism to sugar concentration in the culture. 12% alcohol reduced sugar transport only by 60% showing the ability of Brettanomyces/Dekkera spp to survive even in severe environmental conditions. (We advise you to read the entire article. Original Title: Wine spoilage capacity of Brettanomyces/Dekkera spp.)
