Nutritional requirements for the growth and arthrospore formation of Coccidioides immitis.

Coccidioides immitis, a dimorphic pathogenic fungus, when grown in vitro on solid or in liquid media, usually forms mycelium with septate hyphae which, upon continued incubation, fragment into numerous arthrospores approximately 2 to 4 A in diameter. No definitive studies on the production of arthrospores in chemically defined liquid media have appeared since the work of Roessler et al. (1946), which suggested that additional study of the optimal nutritional conditions might lead to improved growth, sporulation, and fragmentation of this organism. The experiments and results presented here have led to the development of an improved liquid synthetic medium for the production of arthrospores. Both total growth (cellular protein) and viable count have been increased approximately 10-fold above the levels previously reported (Roessler et al., 1946). The requirements for each component of the medium have been studied and the composition reported is believed to be optimal for the growth of C. immitis strain Cash.