Effects of Sodium Chloride on Steady-state Growth and Metabolism of Saccharomyces cerevisiae

Abstract

SUMMARY Sodium chloride decreased the maximum specific growth rate of Sac- charomyces cerevisiae. Chemostat experiments showed this to be largely due to an increased requirement for energy-yielding substrate, apparently linked to maintenance and leading to a decrease in the yield. The increased main- tenance requirement is probably concerned with maintaining an intracellular Na+ concentration ten times lower than the extracellular concentration. NaCl caused much higher concentrations of glucose to be required to main- tain any particular glucose-uptake rate; it also increased the production of glycerol. Organisms used were Saccharomyces cerevisiae IGC 3507 from the culture collection of this laboratory and a respiratory-deficient mutant of it. Experiments were carried out using the mutant unless otherwise indicated in the text. The mutant was chosen to eliminate effects due to variation in respiratory quotient with either change in dilution rate or presence of NaCl and thus to facilitate the computation of yield and maintenance parameters.