INDUCTION OF AN EXTRACELLULAR ESTERASE FROM CANDIDA-ALBICANS AND SOMEOF ITS PROPERTIES

As 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 colorimet ric method using alpha-naphthyl palmitate as a substrate. The inductio n level of the esterase activity was found to be well correlated with fungal growth and was dependent on the Tween 80 concentration. Such es terase activity was observed only in medium containing Tween 80 or oth er Tweens as the sole carbon source and therefore was not observed in either peptone-glucose medium or peptone-glucose medium supplemented w ith Tween 80. The induced esterase was heat labile and had maximum act ivity at pH 5.5. Enzyme activity was stimulated by the addition of sod ium taurocholate, an activator of lipase. Thin-layer chromatography re vealed that this enzyme does not hydrolyze triolein and L-alpha-lecith in, suggesting that it is a monoester hydrolase (not a lipase in the s trict sense of the word). Esterase activity was examined in 85 clinica l isolates of Candida species; C. albicans, C. tropicalis, and C. para psilosis tended to have higher enzyme activities than C. kefyr, C. kru sei, C. glabrata, and C. guilliermondii. Although the physiological pr operties of this exterase are not clear at present, it was found to be crucial for fungal growth under specific conditions.