Cerebrosides, extracellular glycolipids secreted by the selective lignin-degrading fungus Ceriporiopsis subvermispora.

Ceriporiopsis subvermispora is a selective white-rot fungus that degrades lignin at a site far from the hyphae and extracellular enzymes, without intensive damage to the cellulose. In selective ligninolysis, low molecular mass metabolites play a principal role and amphipathic substances are involved to control the degradation and transport of hydrophobic aromatic molecules, including lignin and lipids; however, secretion of the amphipathic substances by this fungus has not been well understood, except for alk(en)yl itaconates called ceriporic acids, which have a weak amphiphilicity. Herein, we report for the first time that the fungus secretes cerebrosides that are classified as glycosphingolipids. By using liquid chromatography electron spray ionization mass spectrometry (LC-ESI-MS) and nuclear magnetic resonance (NMR) spectroscopy coupled with stable isotope feeding experiments with C-glucose and N-ammonium sulfate, the cerebrosides were determined to be N-hydroxyoctadecanoyl-1-O-β-d-glucopyranosyl-4E,8E-sphingadienine, N-hydroxyoctadecanoyl-1-O-β-d-glucopyranosyl-4E,8Z-sphingadienine, and N-hydroxyoctadecanoyl-1-O-β-d-glucopyranosyl-9-methyl-4E,8E-sphingadienine. The cerebrosides are strong amphipathic substances and potential metabolites for regulating difference and symbiosis within the microbial community.