Analysis by HPLC – mass spectrometry of the indole compounds released by the ectomycorrhizal fungus Hebeloma hiemale in pure culture

Abstract

Indole compounds released by Hebeloma hiemale Bres. in pure culture were studied by cultivating the fungus on a nutrient solution supplemented or not with 1 mM tryptophan. Analytical thin-layer chromatography revealed numerous indole compounds in 7-week-old culture filtrates obtained in the presence of tryptophan. Such compounds were isolated by preparative thin-layer chromatography and purified by high performance liquid chromatography. The most abundant of them, i.e., indolyl-3-acetic acid, indolyl-3-carboxylic acid, and indole-3-aldehyde, were identified by mass spectrometry. Indole-3-aldehyde and indolyl-3-carboxylic acid, which were detected in filtrates throughout the culture period, might result from breakdown of indolyl-3-acetic acid by fungal exocellular enzymes.