Fig. 4.

Growth phases in the budding yeast, Sc. Yeast growth on fermentable carbon sources (such as dextrose) is distinguished by four phases. When cells are inoculated into a fresh medium, they initially undergo a lag in growth, known as the lag phase. After the lag phase, yeast cells start a logarithmic growth phase in which the cells use dextrose as a carbon source to produce ethanol. This is the phase of fermentation, also known as the prediauxic phase. When dextrose becomes rare in the media, the cells start utilizing the ethanol available in the media (produced during the fermentation growth) to produce carbon dioxide; this is respiration. This second phase of growth is commonly known as the postdiauxic phase. A stationary phase follows the postdiauxic phase; during this phase, yeast cells do not divide, and thus the growth reaches a plateau.