Acid phosphatase production as an aid in rapid characterization of Candida species.

Yeast isolates were tested for phosphatase activity, using p-nitrophenyl phosphate substrate. Several Candida species displayed characteristic patterns. The enzyme activity was absent in all except one of the 78 isolates of Candida albicans tested. C. tropicalis, C. pseudotropicalis, and C. krusei were the most consistent and active enzyme producers. Enzyme production by these yeasts was not influenced by the amount of growth or a decrease in the pH of the culture media. The characteristic enzyme activity of these three yeasts was demonstrated in the presence of concentrations of inorganic phosphate which inhibited the enzyme activity of other Candida species. The activity of isolates of C. gullermondii, C. parapsilosis, and C. stellatoidea was variable, although none of these were strong enzyme producers. It seems feasible to use phosphatase activity as a simple and rapid additional method for the separation of C. albicans from closely related species of the genus.