High-Resolution LC–MS Characterization of Ramaria flavobrunnescens, a Coral Mushroom Toxic to Livestock, Reveals Fungal, Bacterial, and Eucalyptus Tree Metabolites

<i>Ramaria flavobrunnescens</i> is an ectomycorrhizal coral mushroom that is often found growing in eucalyptus forests. The mushroom has been linked to accidental ingestion-associated livestock poisonings in South America, though the toxicological agent has not yet been described. Mushroom samples identified as <i>R. flavobrunnescens</i> were analyzed by liquid chromatography high-resolution mass spectrometry (LC-MS/MS) to determine the potential source of the toxicity, and to provide a metabolomic profile of the species. Previously reported <i>Ramaria</i> secondary metabolites were detected, including ramarins, ramariolides, pistillarin and arsenic-containing compounds. A number of bacterial species were isolated from <i>R. flavobrunnescens</i> that produced iron-chelating cyclic peptides, which were detected in the mushroom samples. Interestingly, we detected a series of eucalyptus tree secondary metabolites in abundance from <i>R. flavobrunnescens</i> fruiting bodies, some of which have reported toxicities and bioactivities. To our knowledge, this is the first report of eucalyptus secondary metabolites in a mushroom. The diversity of secondary metabolites identified in the mushroom extracts provides insight into the potential complex ecological interactions between <i>R. flavobrunnescens</i>, its associated microbiota, and its mycorrhizal interaction with eucalyptus trees.