Accumulation of magnesium ions during fermentative metabolism in Saccharomyces cerevisiae.

When cells of Saccharomyces cerevisiae were grown aerobically under glucose-repressed conditions, ethanol production displayed a hyperbolic relationship over a limited range of magnesium concentrations up to around 0.5 mM. A similar relationship existed between available Mg2+ and ethanol yield, but over a narrower range of Mg2+ concentrations. Cellular demand for Mg2+ during fermentation was reflected in the accumulation patterns of Mg2+ by yeast cells from the growth medium. Entry of cells into the stationary growth phase and the time of maximum ethanol and minimum sugar concentration correlated with a period of maximum Mg2+ transport by yeast cells. The timing of Mg2+ transport fluxes by S. cerevisiae is potentially useful when conditioning yeast seed inocula prior to alcohol fermentations.