Differences in the composition of phenolics and fatty acids of cultured mycobiont and thallus of Physconia distorta

Abstract

Germinated ascospores of Physconia distorta on an inorganic medium were grown on an enriched medium (Lilly-Barnet medium with 4% glucose), on which they produced swollen hyphae which included numerous lipid droplets. Secondary metabolites extracted from the cultured fungus were analyzed by high performance liquid chromatography and mass spectrometry. Analyses of superficial compounds established the presence of stearic, linoleic and oleic acids, and the corresponding triglycerides. Malonprotocetraric acid, several unknown pigments, and a series of fatty acids were detected as internal compounds. The qualitative and quantitative phenolic and fatty acid composition from the isolated fungal partner and lichenized thalli were different. Fatty acids were the main substances found by liquid chromatography in extracts of axenic cultures, while extracts from intact thalli contain phenolic acids as the main compounds. These results can be explained by metabolic differences as a result of the different available nutrients.