Influence of magnesium ions on heat shock and ethanol stress responses of Saccharomyces cerevisiae

摘要

This study has highlighted the role of magnesium ions in the amelioration of the detrimental effects of ethanol toxicity and temperature shock in a winemaking strain of Saccharomyces cerevisiae. Specifically, results based on measurements of cellular viability and heat shock protein synthesis together with scanning electron microscopy have shown that, by increasing the bioavailability of magnesium ions, physiological protection is conferred on yeast cells. Elevating magnesium levels in the growth medium from 2 to 20 mM results in repression of certain heat shock proteins following a typical heat shock regime (30-42deg C shift). Seed inocula culatures prepropagated in elevated levels of magnesium (i.e.‘preconditioned’) also conferred thermotolerance on cells and repressed the biosynthesis fo heat shock proteins. Similar results were observed in response to ethanol stress. Extra- and intracellular magnesium may both act in te physiological stress protection of yeast cels and this aproach offers potential benefits in alcoholic fermentation processes. The working hypothesis based on our findings is that magnesium protects yeast cells by preventing increases in cell membrnae permeability elicited by ehtanol and temperature-induced stress. Published by Elsevier Science Inc. All rights reserved.