A comparative study of lipids in Sphagnum species

The free lipid compositions of twelve species of Sphagnum were determined by capillary gas chromatography/mass spectrometry as part of a study to identify characteristic lipids for Sphagnum in peat bogs. Complex mixtures of lipids, comprised of C28–C29 sterols, C30 triterpenoids, C16–C30 fatty acids, C22–C30 fatty alcohols, C21–C33 n-alkanes and isoprenoid and straight-chain wax esters, were identified and quantified. Sterols are dominated by the C29 sterols, 24-ethylcholesta-5,22-dien-3β-ol and 24-ethylcholest-5-en-3β-ol, whilst in some species C28 sterols are also abundant. Summed concentrations of triterpenoids varied widely (20–3500 μg/g dry weight), with only small concentrations present in the mesotrophic species, S. fimbriatum and S. palustre. Ursolic acid is always the major triterpenoid detected. Although absolute concentrations vary significantly, the carbon number distributions of fatty acids, fatty alcohols and n-alkanes are similar in all examined species. Thus, the distributions of these compounds, and especially the dominance of C23 and C25 n-alkanes, are a useful chemotaxonomic fingerprint for Sphagnum species and can thus be used in compound-specific 13C and 14C studies of peat bogs.