The Effect of Magnesium and Calcium on Yeast Growth

When inoculated into a defined minimal medium, yeast could not absorb all the magnesium, even if this element was limiting. The cells tended to absorb a constant amount of magnesium, ca 1·1 pg per cell, so long as the content of the medium was sufficient, rather than absorb magnesium in proportion to its initial concentration. Calcium competed with magnesium and prevented yeast growth almost entirely when present at a ten times excess. At a two to three times excess the effect was more on the length of the lag phase and mean generation time than on the total amount of growth.