EFFECT OF IRON CONCENTRATION ON SIDEROPHORE SYNTHESIS AND PIGMENT PRODUCTION BY CANDIDA-ALBICANS

Twelve strains of Candida albicans were grown in defined medium which had been deferrated by ion-exchange chromatography and then supplemented with FeCl3 to give iron concentrations ranging from 0.026-mu-M (growth-limiting) to 0.8-mu-M (excess). All of the strains secreted hydroxamate-type siderophores; phenolate siderophores were not detected. Isolates of C. lusitaniae, C. glabrata and C. parapsilosis also secreted hydroxamate but not phenolate-type iron chelators. Siderophore synthesis by C. albicans was maximal during growth in 0.026-0.2-mu-M iron. These low concentrations of iron also induced the synthesis of a green pigment, with maximal production at 0.026-mu-M. The pigment could be partially separated from hydroxamate siderophore activity on a column of Sephadex G-10 indicating that it probably does not function as an iron chelator.