POTASSIUM AND CALCIUM ION CONCENTRATION INFLUENCE THE ETHANOL TOLERANCE OF YEAST ISOLATES

Ethanol toxicity in the yeast Saccharomyces cerevisiae reduces titre and productivity in the overall industrial production of ethanol. The study aims to evaluate the effect of potassium chloride and calcium chloride on ethanol production, tolerance of yeast cells and to further optimize the salt concentrations in culture medium. Four commercially available strains of yeast were tested for their ethanol tolerance in absence and presence of 10mM to 50mM concentrations of potassium chloride and calcium chloride.. The isolate Saccharomyces cerevisiae strain OR was selected for further tests based on its ethanol tolerance profile. Potassium chloride at 30mM concentration significantly increased viability of the cells in presence of ethanol. The increased of levels of extracellular potassium and calcium ions strengthens transcellular and intracellular ion gradients, thereby potentiating alcohol tolerance of ethanol producing yeast.