Enhancement of yeast ethanol tolerance by calcium and magnesium.

Ethanol-induced changes of CO2 production were compared in three strains of Saccharomyces cerevisiae. CaCl2 and MgCl2 exerted protective effects against the action of ethanol. Optimal concentrations ensuring maximum of CO2 production at 10% (V/V) of ethanol under non-growing conditions were 3 mmol/L Ca2+ and 2 mmol/L Mg2+. Yeast growth with and without ethanol addition was stimulated by Mg2+ more than by Ca2+ during fermentation, whereas ethanol production was more efficient when both Ca2+ and Mg2+ were added.