Michael Nicholson

Sami, M., Ikeda, M., & Yabuuchi, S. (1994). Evaluation of the alkaline methylene blue staining method for yeast activity determination. Journal of Fermentation and Bioengineering, 78 (3), 212-216.


1.  The alkaline methylene blue (AMB) method is used to identify physiologically competent yeast cells, and is a modification of the standard methylene blue (SMB) method (p. 212).
2.  AMB is reported to be a "sensitive, quick, and simple means of determining yeast activity" (p. 212).
3.  Three methods were tested against AMB for evaluation purposes:  SMB, slide culture method (SCM), and acidification power test (APT) (p. 212).
4.  SCM and APT took too long to implement, though they offer good results (p. 213).
5.  With the SMB method, the dye only enters into cells that are dead, so a variety of factors (including age of the particular culture) may influence the apparent activity of the yeast (p. 215).
6. The AMB method, because of the pH factor, allows the dye to more easily enter living cells; the constant quantity of dye entering the cells reflects "the intracellular reducing power" of the cells, such that fewer partially or completly dyed cells indicates greater cellular activity (p. 215).