MAGNESIUM AS A STRESS-PROTECTANT FOR INDUSTRIAL STRAINS OF SACCHAROMYCES-CEREVISIAE

During brewery fermentations, individual yeast cells may be confronted with a variety of environmental stresses that impair yeast growth and fermentative metabolism. An understanding of the stress physiology of industrial yeasts is therefore important in order to counteract delet erious effects of stress on fermentation and, ultimately, product qual ity. The present study describes the influence of magnesium ions in pr eventing cell death caused by temperature shock and ethanol toxicity i n Saccharomyces cerevisiae yeast strains employed in brewing, distilli ng, and wine fermentations. Results obtained show that, by increasing the extracellular availability of magnesium ions, physiological protec tion may be conferred on temperature- and ethanol-stressed yeast cells with respect to culture viability and growth. This practical approach is envisaged to offer benefits to alcoholic fermentation processes in terms of enhancing the viability of the yeasts employed. It is propos ed that magnesium prevents stress-induced damage to yeast cells by pro tecting the structural and functional integrity of the plasma membrane .