Pigments of the genus Beauveria

Abstract

Red coloring substances found in isolates of the imperfect fungus Beauveria were identified as the dibenzoquinone pigment oosporein. Yellow pigments were isolated from both B. bassiana and B. tenella cultures and found to be mixtures of similar compounds. Two types (designated tenellins and bassianins) occurred. Their distribution did not follow species lines. In cultures of a B. tenella isolate which produced both red and yellow pigments the optimum yield of oosporein was obtained with a glycerol–nitrate–salts medium and was unaffected by excess nitrogen source. Zinc ions stimulated and manganese ions depressed production. The optimum yield of bassianins occurred on a glucose – ammonium tartrate – salts medium with a high carbon:nitrogen ratio. Phosphate, above minimum requirements for growth, did not strongly influence the yield of either pigment. On a medium in which both oosporein and bassianins were produced, oosporein was formed first. Bassianins were accumulated rapidly only after depletion of the nitrogen source.