Possible primary ecological niche of Cryptococcus neoformans

To study hollows of living trees as natural habitats of Cryptococcus neofor mans in an endemic area of cryptococcosis in the northeastern region of Bra zil, samples of decaying wood were collected inside 32 hollows of living tr ees and plated on niger seed agar. Identification of C. neoformans was base d upon morphological and physiological tests. Canavanine-glycine-bromothymo l medium was used to screen the varieties and Crypto Check Iatron Kit to se rotype the isolates. A total of 123 C. neoformans colonies were recovered f rom samples of six (18.5%) out of 32 hollow trees. C. neoformans var. neofo rmans and C, neoformans var, gattii were found occurring alone (pink shower tree, fig tree and pottery tree) or sharing the same hollow (pink shower t ree). Long lasting positivity (19-36 months) and significant number of cfu of C. neoformans per gram of decaying wood (0.15-21.7 x 10(3) cfu g(-1)) in side hollows of pink shower tree, fig tree and pottery tree were observed, indicating colonization of these habitats by the fungus. For the first time , C. n, var, neoformans and C. n, var. gattii were found sharing the same n atural biotope, thus establishing a possible link between them in their lif e cycle in nature and suggesting the primary natural niche for the species.