Glycogen metabolism in resting and growing cells of Saccharomyces carlsbergensis

Saccharomyces carlsbergensis cells, growing under carbohydrate or nitrogen limitation, initially deplete their glycogen, which is resynthesized only during the late exponential phase. Cells, harvested in the carly exponential phase, are even unable to synthesize glycogen in glucose-containing phosphate buffer. This is in contrast to cells from the stationary phase which rapidly synthesize glycogen under the same conditions. Lack of O₂ slows down glycogen synthesis.Contrary to cells suspended in complete medium, addition of ammonia alone to nitrogen free-media induced neither breakdown of glycogen, nor complete cessation of glycogen synthesis. Ammonia slowed down glycogen synthesis (both aerobic and anaerobic), only, in cells grown either under carbohydrate or under nitrogen limitation.Glycogen synthesis was observed 1 min after addition of glucose to a starved cell suspension in phosphate buffer. Removal of the sugar from the buffer resulted in an instantanous decrease of the glycogen level in the cells. The results indicate that glycogen-metabolism is regulated by a variety of endogenous and environmental factors.