Growth curves of the yeast-like form of Paracocidioides bradiliensis.

Growth curves of the yeast-like form of 4 strains of Paracoccidioides brasiliensis based on colony counts on GGY agar and on cell counts weree made. Mean generation times wer 17, 13 and 21 h. for 3 of the strains. The kinetics of growth for all strains showed that dead cells were present in approximately the same proportion as living cells in the initial inocula and their number increased through the exponential phase of growth at a similar rate as that of living cells. Viability counts made in 2-week old cultures of all strains were negative. It is suggested that during growth P. brasiliensis continuously diffuses a metabolite which is lethal to the fungus. Strains of Blastomyces dermatitidis and Histoplasma capsulatum were also sensitive to this lethal effects.