Inhibition of germ tube formation, filamentation and ergosterol biosynthesis in Candida albicans treated with 6-amino-2-n-pentylthiobenzothiazole

Three representative Candida albicans strains were selected out of 26 clini cal isolates and strains from culture collections on the basis of their hig h level of conversion to germ tubes and mycelial form at mycelium-promoting culture conditions, and on their different sensitivity to 6-amino-2-n-pent ylthiobenzothiazole (APB). When these strains were treated with APE at myce lium-promoting culture conditions, a concentration-dependent decrease in th e proportion of germ tubes and hyphae was observed, while the proportion of the yeast form increased. When non-saponifiable lipids were extracted from these cultures and analyzed, a concentration-dependent decrease in ergoste rol and an increase in 4-methylated sterols was observed. However, the sens itivity of sterol biosynthesis did not directly relate to the sensitivity o f the morphological conversion, and was exhibited at higher concentrations of APE. On the basis of these results it is suggested that the inhibition o f germ tube formation and filamentation is not a consequence of inhibition of ergosterol biosynthesis in APE-treated C. albicans.