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.
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).