Acetaldehyde mediates growth stimulation of ethanol-stressed Saccharomyces cerevisiae: Evidence of a redox-driven mechanism

The ability of acetaldehyde (90 mg l-1) to stimulate ethanol-stressed S. cerevisiae fermentations is examined and reasons for the effect explored. Alternative metabolic electron acceptors generated similar stimulatory effects to acetaldehyde, decreasing the ethanol-induced growth lag phase from 9 h to 3 h, suggesting a redox-driven effect. The exposure to ethanol caused an instant 60% decline in intracellular NAD+ which was largely prevented by the addition of acetaldehyde. Furthermore, the exposure to ethanol affected glycolysis by decreasing the rate of glucose utilisation from 0.33 g glucose g-1 biomass h-1 to 0.11 g glucose g -1 biomass h-1, while the addition of acetaldehyde to an ethanol stressed culture increased this rate to 0.14 g glucose g-1 biomass h-1. © 2007 Springer Science+Business Media B.V.C