Factors Determining the Ergosterol Content of Yeast

Following the discovery of ergosterol by Tanret (l), Gerard (2) observed that not only ergot, but fungi in general, contain it. Gerard was the first to recognize ergosterol in yeast, although Nageli (3) had earlier obtained a yeast “cholesterol” in crude form. In traces ergosterol is now known to be widely distributed in both plant and animal kingdoms, but the fungi, and particularly the yeasts, remain its practical source. Few studies have been reported on the factors which determine the ergosterol content of yeast. MacLean and Hoffert (4) noted differences in the sterol content of different samples, and MacLean (5) increased the sterol content of a given yeast by incubation in a phosphate-carbohydrate solution. Heiduschka and Lindner (6) compared the ergosterol content of ten fungi, including yeasts, finding from 0.29 to 1.17 per cent of ergosterol in the dry substance. They observed that the ergosterol content was influenced considerably by the composition of the wort. Bills and Cox (7) reported that one bakers’ yeast yielded 10 times as much ergosterol as another, and that the two specimens of ergosterol were not identical, but more or less isomeric. In 1927 it was observed that the bakers’ yeast which we were attempting to use as a source of commercial ergosterol varied greatly in sterol content. Since care is exercised in the manu-