Determination of the growth curves of the mycelial and yeast forms of Paracoccidiodes brasiliensis.

Abstract

The growth curves of 2 different strains of P. brasiliensis were determined. Cultures were made in a dialyzed trypticase soy broth and the growth assesed at selected intervals by means of viable cell counts. In the yeast form, both strains exhibited un uniform pattern of growth; the mycelial forms were also similar although one of the strains survived for a longer period of time. When the 2 yeast curves were compared with the mycelial ones, large differences were noticed. Thus, the mean survival time for the yeasts was 13.5 days while it was 50.25 days for the mycelia. During the exponential phase, the mean rate of growth was accelerated for the yeasts (0.110) in comparison with the one exhibited by the mycelia (0.0265). Irrespective of the form of growth and for both strains, death occurred abruptly, a few hours after a period when colony counts were high, indicating that the fugus was viable at the preceeding interval.