Carotenogenesis associated with arthrosporulation of Trichophyton mentagrophytes.

Carotenoid pigments were demonstrated in arthrospores of the dermatophyte Trichophyton mentagrophytes but were absent from hyphae and microconidia of this fungus. Incubation at higher temperatures (39 degrees C) allowed arthrosporulation to occur, but essentially no carotenoid was detected in such arthrospores. The carotenoid formation in arthrosporulating T. mentagrophytes did not appear to be either induced or stimulated by light illumination. Mature arthrospores contained the carotenoids phytoene, phytofluene, zeta-carotene, neurosporene, lycopene, and gamma-carotene and a few minor unidentified carotenoids. These carotenoids were localized within intracellular granules consisting of osmiophilic matrices and complex membranous elements. This is the first demonstration of carotenoid pigments in dermatophytic fungi.