Induction of an extracellular esterase from Candida albicans and some of its properties

Abstract

An extracellular esterase from Candida albicans A-714 was found to be induced in a medium containing 0.7% yeast nitrogen base and 2.5% Tween 80 (polyoxyethylenesorbitan compounds). Enzyme activity, which exists predominantly in the extracellular space, was measured by a colorimetric method using alpha-naphthyl palmitate as a substrate. The induction level of the esterase activity was found to be well correlated with fungal growth and was dependent on the Tween 80 concentration. Such esterase activity was observed only in medium containing Tween 80 or other Tweens as the sole carbon source and therefore was not observed in either peptone-glucose medium or peptone-glucose medium supplemented with Tween 80. The induced esterase was heat labile and had maximum activity at pH 5.5. Enzyme activity was stimulated by the addition of sodium taurocholate, an activator of lipase. Thin-layer chromatography revealed that this enzyme does not hydrolyze triolein and L-alpha-lecithin, suggesting that it is a monoester hydrolase (not a lipase in the strict sense of the word). Esterase activity was examined in 85 clinical isolates of Candida species; C. albicans, C. tropicalis, and C. parapsilosis tended to have higher enzyme activities than C. kefyr, C. krusei, C. glabrata, and C. guilliermondii. Although the physiological properties of this esterase are not clear at present, it was found to be crucial for fungal growth under specific conditions.