VIABILITY AND MORPHOLOGICAL ALTERATIONS OF PARACOCCIDIOIDES-BRASILIENSIS STRAINS PRESERVED UNDER MINERAL-OIL FOR LONG PERIODS OF TIME

We evaluated the survival and the morphological alteration of 70 strai ns of Para-coccidioides brasiliensis maintained in the Fungal Culture Collection of Institute Oswaldo Cruz and initially preserved by succes sive subculturing and later under mineral oil at room temperature from 1923 to 1992. Of the 70 strains preserved under mineral oil, 18 (26%) continued to be viable. The mycelia of the 18 viable strains and the mycelia of four representatives of the non-viable strains presented tr ansitional micromorphology under mineral oil. Macroscopy and microscop y of the first subcultures of five of the seven strains, taken as rand om samples from the 18 viable strains and plated onto peptone-yeast ex tract-glucose agar, glucose-glycine-yeast extract agar and brain-heart infusion agar media at room temperature, revealed that all samples ap peared to be in a transition phase (Y reversible arrow M). These five strains were unable to grow and complete thermal dimorphism at a tempe rature of 37 degrees C. Only two strains were able to complete the ent ire dimorphic process. The period of preservation of these strains und er oil was relatively short, i.e. 9 and 10 years. The results demonstr ate that less widely spaced subculturing and more appropriate culture and environmental conditions are needed to preserve P. brasiliensis st rains under oil.