The mode of occurrence of lipids in a Namibian Shelf diatomaceous ooze with emphasis on the β-hydroxy fatty acids

Lipids present in a recent marine sediment were extracted, derivatized and analysed by GC and GCMS, without preseparation. This combination of methods offers the possibility to determine various classes of lipids simultaneously. Selective chemical treatment prior to the total lipid extraction, enables the determination of the mode of occurrence in the sediment and might yield more appropriate information about the origin of individual lipid moieties released. The significant relative abundancies of β-hydroxy fatty acids and the structural features of these acids among the lipids released after acid treatment point to the presence of bacterial cell wall material in the sediment sample. This suggestion was supported by a separate isolation of bacterial cell wall lipopolysaccharide.