A comparative study of lipids in Sphagnum species

The free lipid compositions of twelve species of Sphagnum were determined b y capillary gas chromatograghy/mass spectrometry as part of a study to iden tify characteristic lipids for Sphagnum in peat bogs. Complex mixtures of l ipids, comprised of C28C29 sterols, C-30 triterpenoids, C-16-C-30 fatty aci ds, C-22-C-30 Fatty alcohols, C-21-C-33 n-alkanes and isoprenoid and straig ht-chain wax esters, were identified and quantified. Sterols are dominated by the C-29 sterols, 24-ethylcholesta-5,22-dien-3 beta-ol and 24-ethylchole st-5-en-3 beta-ol, whilst in some species C-28 sterols are also abundant. S ummed concentrations of triterpenoids varied widely (20-3500 mu g/g dry wei ght), 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 n umber distributions of fatty acids, fatty alcohols and n-alkanes are simila r in all examined species. Thus, the distributions of these compounds, and especially the dominance of C-23 and C-25 n-alkanes, are a useful chemotaxo nomic fingerprint for Sphagnum species and can thus be used in compound-spe cific C-13 and C-14 studies of peat bogs. (C) 2000 Elsevier Science Ltd. Al l rights reserved.