EFFECT OF ACETALDEHYDE ON SACCHAROMYCES-CEREVISIAE AND ZYMOMONAS-MOBILIS SUBJECTED TO ENVIRONMENTAL SHOCKS

The lag phase of Saccharomyces cerevisiae subjected to a step increase in temperature or ethanol concentration was reduced by as much as 60% when acetaldehyde was added to the medium at concentrations less than 0.1 g/L. Maximum specific growth rates were also substantially increa sed. Even greater proportional reductions in lag time due to acetaldeh yde addition were observed for ethanol-shocked cultures of Zymomonas m obilis. Acetaldehyde had no effect on S. cerevisiae cultures started f rom stationary phase inocula in the absence of environmental shock and its lag-reducing effects were greater in complex medium than in a def ined synthetic medium. Acetaldehyde reacted strongly with the ingredie nts of complex culture media. It is proposed that the effect of added acetaldehyde may be to compensate for the inability of cells to mainta in transmembrane acetaldehyde gradients following an environmental sho ck. (C) 1997 John Wiley & Sons, Inc.