The ViaStain™ Yeast Kit for Live/Dead Concentration enables the user to quantitatively distinguish live and dead yeast in pure cultures and in cultures containing debris such as corn mash using the Cellometer systems. The kit contains a solution of the green-fluorescent nucleic acid stain, acridine orange, and the red-fluorescent nucleic acid stain, propidium iodide, and a dilution buffer. Propidium iodide is a membrane exclusion dye that only enters cells/yeast with compromised membranes while acridine orange penetrates all cells/yeast in a population. When both dyes are present in the nucleus, propidium iodide causes a reduction in acridine orange fluorescence by fluorescence resonance energy transfer (FRET). As a result, yeast with intact membranes stain fluorescent green and are counted as live, whereas yeast with compromised membranes only stain fluorescent red and are counted as dead when using the Cellometer instruments.