Physiological changes following the breaking of dormancy of Saccharomyces cerevisiae ascospores

Abstract

Optimal conditions have been defined for obtaining a synchronously germinating ascospore population of Saccharomyces cerevisiae. A rapid response was elicited when a yeast spore suspension was incubated in a nutritionally sufficient medium supplemented with glucose in a pH range of 5.4 to 8.2, and aerated at 30 °C. Lipids were used mainly during the swelling phase of the spore outgrowth. Respiratory studies revealed a burst of CO₂ evolution 15 min after the onset of germination, and 3 h later a break in the rates of CO₂ production, O₂ consumption, and glucose uptake. During germination the pH of the medium decreased. These results suggested shifts in metabolism during germination and outgrowth of yeast spores.