The role of chlamydospores of Paracoccidioides brasiliensis

Abstract

The role of chlamydospores in the conversion process from a mycelial-to-yeast form using the slide culture method was studied. Three clinical isolates and two other isolates from armadillo, belonging to the fungal species Paracoccidioides brasiliensis, were cultured on Sabouraud dextrose agar (SDA), potato dextrose agar (PDA) and brain heart infusion dextrose agar (BHIDA). Initially, the mycelial forms of each isolate were grown at 25°C for 7, 14, 30 or 60 days on slide cultures and then the temperature was shifted to 35°C. Interestingly, the slide cultures of all the isolates at 25°C formed chlamydospores on either SDA or BHIDA, whereas, on PDA medium, aleurioconidia were formed. If the slide cultures on BHIDA were incubated at 35°C for 7 to 14 days, multiple budding forms could be observed. This phenomenon was not evident in the slide cultures of SDA or PDA. The results of this morphological study indicate that in P. brasiliensis, chlamydospores may play an important role in the conversion process from a mycelial-to-yeast form.