Endogenous Metabolism of Freshly Harvested Cells of a Brewer's Yeast

Abstract

WASHED cell suspensions of yeast have been reported as being able to respire their carbohydrate reserves but unable to ferment these reserves even when the cells were freshly harvested^1,2. Other workers have reported that an alcoholic fermentation of these reserves is induced in the presence of dinitrophenol, azide and arsenite^3,4. In the present work it has been found that in a brewer's yeast (Saccharomyces cerevisiae) the carbohydrate reserves are degraded by a fermentation process under both aerobic and anaerobic conditions. As a result of this fermentation the total carbohydrate content of the yeast in a suspension at 28° C. decreased by as much as 50 per cent in the 5 hr. following harvesting. The decrease in the trehalose and glycogen fractions accounted for all the loss of carbohydrate.