How do you identify living cells and dead cells within a culture of yeast?
dead cells stain blue
To identify living and dead cells within a culture of yeast, two commonly used methods are:
1. Trypan blue staining: Trypan blue is a vital stain that can penetrate dead cells while it cannot pass through the membrane of living cells. This staining method involves mixing a sample of yeast culture with an equal volume of trypan blue solution (0.4% w/v) and allowing it to stand for a few minutes. Dead cells which are stained blue can be distinguished from living cells which are unstained.
2. Fluorescent dyes: Fluorescent dyes such as propidium iodide (PI) and SYTO9 are also commonly used to differentiate living and dead yeast cells. PI is a DNA binding dye that is excluded from living cells but can penetrate dead cells. SYTO9, on the other hand, can penetrate both living and dead cells but exhibits stronger fluorescence in living cells due to the integrity of their membrane. This staining method involves incubating the yeast culture with a mixture of both dyes for about 10-15 minutes. Dead cells which are stained red by PI can be distinguished from living cells which are stained green by SYTO9.
Both of these methods can be visualized under a light microscope or flow cytometer to quantify and distinguish between living and dead cells.