RELEASE OF NITROGENOUS SUBSTANCES BY BREWER'S YEAST III

Abstract

Lewis , M. J. (University of California, Davis), and H. J. Phaff . Release of nitrogenous substances by brewers' yeast. III. Shock excretion of amino acids. J. Bacteriol. 87: 1389–1396. 1964.—When Saccharomyces carlsbergensis (two strains) and S. cerevisiae (one strain) were grown in static culture and the harvested, washed cells were suspended in a solution of glucose, amino acids were suddenly released and then rapidly reabsorbed in a space of about 2 hr. The phenomenon of amino acid release, which was termed shock excretion, varied in intensity with the strain of yeast and was shown to be dependent on the size of the pool of free amino acids within the cells. Shock excretion was independent of osmotic pressure of the suspending medium, but required the presence of a fermentable sugar. d -Galactose and maltose caused shock excretion only when yeast was previously adapted to these sugars. Limiting glucose concentrations prevented reabsorption of amino acids, and a further decrease in glucose concentration also limited excretion. Shock excretion was strikingly reduced when the temperature of the suspending medium was lowered.