Diverse rare lipid-related metabolites including ω-7 and ω-9 alkenylitaconic acids (ceriporic acids) secreted by a selective white rot fungus, Ceriporiopsis subvermispora

Abstract

Ceriporiopsis subvermispora is a selective white-rot fungus that secretes alk(en)ylitaconic acids named ceriporic acids, known as ion redox silencers. In this study, we analysed a series of extracellular lipid-related metabolites produced by the fungus and found that a wide variety of ceriporic acids and fatty acids, including those with odd-numbered and very long-chains, were produced in wood meal cultures. Two new ceriporic acids, ( R)-3-[( Z)-tetradec-7-enyl]-itaconic acid (ceriporic acid E) and ( R)-3-[( Z)-tetradec-5-enyl]-itaconic acid (ceriporic acid F), were for the first time identified by dimethyl disulfide derivatisation, followed by GC/EI-MS, 1H and homonuclear J-resolved 2D NMR and feeding experiments with [ 13C-U] glucose coupled with multiple-stage mass spectrometry. In separation by GC and LC, a reversed correlation of elution sequences between a nonpolar GC column and an ODS-LC column for cis and trans isomers of ω7 and ω9 lipids was found, and the elution of new metabolites was in accordance with the prevailing theory. The biosynthetic precursors of ceriporic acid F can be proposed as oxaloacetate and 16:1Δ7-CoA. Because fatty acids biosynthesised from 16:1Δ7-CoA have been reported for only a limited number of organisms, the highly individual structure of ceriporic acid F is highlighted.