Evaluation of the Fluorescent Dye 1-Anilino-8-Naphthalene Sulfonic Acid for Yeast Viability Determination

The use of a protein-staining fluorochrome, the magnesium salt of 1-anilino-8-naphthalene sulfonic acid (Mg-ANS), to determine yeast viability is described. When compared with the two brightfield dye methods employing methylene blue or eosin Y, Mg-ANS yielded viabilities statistically similar to those of the slide culture method. The linear regression coefficients were 0.9994, 0.9870, and 0.8709 for results of Mg-ANS, eosin Y, and methylene blue, respectively. In addition, when the hemocytometer was used, Mg-ANS staining results were statistically indistinguishable from the slide culture results. The regression coefficient was 0.9996 when the hemocytometer was used with Mg-ANS staining and 0.9994 without the hemocytometer. More importantly, the y-intercept of the regression line was closer to the origin (0.0) at 0.43 when the hemocytometer was used. When analysis took place using Mg-ANS staining and a plain microscope slide, the y-intercept was 2.71. Use of the hemocytometer allowed a simultaneous determination of both yeast in suspension and viability.