Creatinine metabolism in Cryptococcus neoformans and Cryptococcus bacillisporus

Abstract

The pathogenic Cryptococcus, spp., C. neoformans and C. bacillisporus, utilized creatinine as a source of N but not of C. Chromatographic and autoradiographic studies suggest that creatinine metabolism in both species involves a single step resulting in the production of methylhydantoin and NH3. The enzyme responsible for this step, creatinine deiminase, was produced by the cells only in the presence of creatinine in both species. The synthesis of creatinine deiminase was repressed by NH3 in C. neoformans, but not in C. bacillisporus. A possible explanation for this variation, based on the ecological differences between the 2 spp., is discussed. A novel method for measuring creatinine deiminase activity is also described.