Fluorescein Diacetate Stain and Propidium Iodide Stain for Yeast are used to assess cell viability. Viable cells hydrolyze fluorescein
diacetate into the green fluorescent compound fluorescein, causing viable cells to fluoresce green. Not being able to permeate
intact cell membranes, propidium iodide is taken up by nonviable cells and cells with compromised membranes binding to the nucleus of nonviable cells and causing them to fluoresce red