EFFECT OF NYSTATIN ON THE UTILIZATION OF SUBSTRATES BY YEAST AND OTHER FUNGI

Abstract

Nystatin, a polyene antifungal anti-biotic, inhibits the aerobic and anaerobic utilization of various sugars by fungi at concentrations approximating those required to inhibit growth. Both growth and sugar utilization by bacteria were not affected. With yeast high levels of nystatin cause an initial stimulation of O2 con-sumption on glucose. Then metabolism ceases abruptly and the cells are no longer viable. An increased total O2 consumption is observed with low levels of the antibiotic, suggesting an uncoupling action somewhat similar to that of dinitrophenol. Inhibition is more rapid at pH 4.5 than at pH 6.5 and occurs at lower concentrations. Reversal of the inhibition has not been observed. Prevention has occurred only with materials which bind nystatin. Penetration of the cell by glucose does not appear to be blocked, since the cell space in rapid equilibirum with glucose is the same in the presence and absence of nystatin.