Correlation between the sterol composition of membranes and morphology in Candida albicans

The opportunistic pathogenic fungus Candida albicans was examined in three distinct morphological forms: yeast, mycelia, and stunted mycelia obtained by growing cells under mycelial-inducing conditions in the presence of ketoconazole at concentrations below the MIC. Comparison of the sterols of the parental strain with those from a mutant unable to produce mycelia, by TLC and GLC, showed no significant differences in sterol composition between the yeast and mycelial morphological forms. However, ketoconazole-treated cells possessed a lower ergosterol content and an increased amount of 14-methylated sterol precursors. The effect of ketoconazole on mycelial cells was quantitatively different from the effect on yeast cells in that the ratio of 4, 14-dimethylsterols to 4-methylsterols was significantly lower in the stunted mycelial morphological forms. A comparison of the effect of terbinafine on sterol biosynthesis and morphology suggests that the effect on ergosterol content is of greater importance than the increase in sterol precursors in determining cell shape.