Enumerative fluorescent vital staining of live and dead pathogenic yeast cells

A quantitative technique is presented for differentiating live and dead yeast cells grown in culture through the use of the fluorescent dye acridine orange. The method gives results that correlate well with those of other commonly used vital staining techniques and is free of certain interpretative errors inherent in them. Vital staining of yeasts with acridine orange also allows for more precise assessment of the physiological state of individual cells and the culture as a whole. The progressive senescence of yeast cells in culture can be monitored by the changing staining characteristics of several subcellular organelles. The method is simple and reliable.