Lipidomic Analysis of Clostridium cadaveris and Clostridium fallax

The lipidomes of Clostridium fallax and Clostridium cadaveris were studied using thin-layer chromatography (TLC) and normal phase liquid chromatography/mass spectrometry (NPLC/MS). Both species contain diradylglycerol (DRG), monohexosyldiradylglycerol (MHDRG), monohexosyl monoacylglycerol (MHMAG), phosphatidylglycerol (PtdGro), and phosphatidylethanolamine (PtdEtn). DRG, MHDRG, PtdEtn, and PtdGro are present in both diacyl and alk-1-enyl acyl (plasmalogen) forms. Both species contain cardiolipin (Ptd₂Gro), which is present in tetraacyl, monoalkenyl-triacyl, and dialkenyl-diacyl forms. Both species contain small amounts of phosphatidylcholine (PtdCho). The presence of octadecadienoic (18:2) acyl chains in some PtdCho species indicates that they arise from the medium because no 18:2 is seen in the other lipids and clostridia generally lack the capacity to synthesize polyunsaturated fatty acids. The major lipidomic differences between these two species are that C. fallax contains a glycerolacetal of plasmenylethanolamine while C. cadaveris contains an ethanolamine-phosphate-modified diacylglycerol. The significance of these lipid compositions is discussed.