Elastase activity of Coccidioides immitis

Twenty-two strains of Coccidioides immitis were tested for the ability to hydrolyse elastin. Screening assays with Czapek's or Tryptic Soy Agar supplemented with 0.5% elastin demonstrated that 21 strains (95%) were elastolytic. In broth cultures, elastase activity was induced by incorporation of insoluble elastin into the medium and induction was suppressed by supplementation with yeast extract. C. immitis appears to be unique amongst dimorphic fungal pathogens in its digestion of elastin.