Beiträge zur Methylenblaufärbung der Hefezellen und Studien über die Permeabilität der Hefezellmembran. I. Mitteilung.

Abstract

This method has been employed for some time in microscopical investigations for differentiation of living and dead yeast cells. This study was made from the point of importance to the brewing industry. Only dead cells were thought to take up the stain. A critical study of the permeability of the yeast-cell membrane indicated that the amount of stain taken up as well as the number of cells stained depended on the pH value of the suspension. Yeast cells from new beer after 60 hrs. in the vat showed only 1% of blue cells when suspended in well water or in 5% sucrose-well-water solution two minutes after addition of methylene blue but 4% and 5% respectively after 15 minutes. With distilled water and sucrose the percentages were 4%, 8%; and 26% and 85% respectively. Action was perhaps equal with sucrose, glucose, levulose and galactose but somewhat less with maltose. Many cells that stained a deep blue retained their capacity for reproduction. In distilled water, color is taken up quickly by the cells while in tap water in equal time they remain practically constant. In a few minutes 98% of the cells in the salt-free sugar solution became a deep blue while in the tap water only a little dye was taken up in the presence of sugar. In the electrolyte-free fermentation mixture fermentation was less active than in the presence of salts. Addition of methylene blue hindered fermentation but this was almost completely overcome by addition of salts. If anions and cations considered in this experiment are arranged according to their relative activity, they appear essentially as in the Hofmeister series.