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.