On the uptake of nystatin by Saccharomyces cerevisiae. 2 Effects of pH, ionic strength, sterol concentration and "protecting" ions.

Uptake of nystatin by sensitive cells of Saccharomyces cerevisiae was studied as a function of pH and ionic strength. The pH was shown to affect radically uptake kinetics and extent, whilst ionic strength variation appeared not to modify uptake at all. The effects of variation in the sterol concentration of the cells employed showed a decrease in nystatin uptake as sterol concentration increased. This was not the anticipated observation. Calcium ions were shown to "protect" the yeast cells by associating with the cell and not the antibiotic. Possible explanations are discussed.