Role of osmotic stress and amino acid deprivation in Paracoccidioides brasiliensis dimorphism

Paracoccidioidomycosis (PCM) is the most important systemic mycosis in South America, causing many deaths in the countries where it occurs. The disease is caused by the thermo-dimorphic fungi Paracoccidioides brasiliensis and Paracoccidiodes Lutzii, found in nature under a mycelial form (M) and as a yeast (Y) in host tissues. Transition between these two forms depends on the growth temperature, being M at 25C and yeast at 37C. This work aimed to evaluate the effect of osmotic stress, lack of glucose and amino acid deficiency in P. brasiliensis dimorphism. Here we show that yeast to mycelium transition is inhibited, at room temperature, during osmotic stress and amino acid deprivation conditions, but fungal cells maintain its growth rate and viability. Our data add to extensive available literature indicating that P. brasiliensis dimorphism does not depends exclusively on growth temperature, and its morphogenesis can be influenced by multiple factors.