Past work in this laboratory has shown that the stationary populations of 8. cerevisiae produced in a yeast extract medium during serial transfer under continuous anaerobic conditions mere quite small, while excellent growth occurred in the presence of oxygen (Brockmann and Stier, '47). It was also shomm that the anaerobic population could be greatly increased by supplementing the medium with various crude materials, such as vegetable oils, malt sprouts and distillers' dried solubles, or their unsaponifiable fractions. This Pesult indicated that sterols might have special significance in the anaerobic growth of yeast (Stier and Scalf, '49; Stier et al., '50; Scalf and Stier, '50).
In order to proceed with studies on the role of sterols in anaerobic growth, it was necessary to change from the yeast extract medium that had been used in previous work to a chemically defined basal medium. It is the object of this report to describe this medium and especially to show the effect on anaerobic growth of adding a yeast sterol, ergosterol, to this medium. A comparison of anaerobic and aerobic growth is also given.
EXPERIMENTAL PROCEDURES
Yeast strnirz. All experiments were conducted with a distillery type yeast; a strain of S. cereuisiae, SC-1 (DCL), This work was aided by a grant from Joseph E. Seagram