Effect of Light on Carotenoid and Riboflavin Production by the Fungus Cephalosporium diospyri

Abstract

SUMMARY: Carotenoids were produced in the mycelial form of Cephalosporium diospyri only after exposure to light of wavelength < 500 nm, and production occurred in three stages. The initial photoinduction required light and was temperature-independent. Both subsequent dark stages, consisting of a lag period and of actual synthesis of carotenoids, were temperature-dependent. All steps had an absolute requirement for oxygen. Filtrates from dark-grown cultures contained ribo-flavin, while lumichrome was present in filtrates from light-grown cultures. Intracellular riboflavin levels were the same in both. Concentrations of diphenyl-amine which inhibited carotenogensis in light-grown cultures also inhibited extracellular production of riboflavin by dark-grown organisms. Several compounds with known photomimetic properties were tested on dark-grown mycelia, but pigmentation was induced only in plate cultures containing p-hydroxymercuri-benzoate. These pigments had the appearance of carotenoids, but have not been chemically characterized.