Magnesium ions improve growth and ethanol production of Zymomonas mobilis under heat or ethanol stress

Abstract

Like other ethanologenic organisms, Zymomonas mobilis showed a significant decrease in cell viability and fermentation capability when the initial ethanol concentration or temperature was elevated. The cell mass and ethanol production were largely decreased at more than 35°C or in the presence of higher than 7% (by vol) ethanol at an initial concentration. Neither growth nor ethanol production was observed at more than 40°C or at higher than 14% (by vol) ethanol. The supplementation of magnesium (10-20 mM) dramatically improved the negative effects by these stresses. Magnesium also increased in fermentation ability and repressed the synthesis of stress proteins under such conditions. These results clearly demonstrated the usefulness of magnesium for ethanol fermentation in Z. mobilis under heat or ethanol stress. © 2007 Asian Network for Scientific Information.