EXTRACELLULAR PROTEOLYTIC-ENZYME ACTIVITY OF HISTOPLASMA-CAPSULATUM VAR DUBOISII

Histoplasma capsulatum var. duboisii is the etiological agent of Afric an histoplasmosis, an important deep mycosis in West Africa. Not much is known about the physiological properties of this fungus. This commu nication reports on the extracellular proteolytic enzyme activity of t his fungus. Five isolates of this fungus tested hydrolyzed azocasein a nd bovine serum albumin at pH 6.8 and 8.0. Assay of the crude enzyme s howed that proteolytic activity increased with age and peaked on the 1 0th day and then again on the 13th day for the yeast form, and on the 11th day of growth for the mycelial form. The optimum temperature and pH for maximum enzyme activity were 35 degrees C and 6.8 respectively. The proteinase activity was more pronounced with the yeast form than with the mycelial form. The action of enzyme inhibitors suggested the presence of an aspartyl proteinase.