Note Occurrence of fatty acids linked to non-phospholipid compounds in the polar fraction of a marine sedimentary extract from Carteau cove, France E. Aries a, *, P. Doumenq a , J. Artaud a , J. Molinet a , J.C. Bertrand b a Laboratoire de Chimie Analytique de l'Environnement ESA CNRS 6171, Faculte  des Sciences de Saint-Je Âro à me, Avenue Escadrille, Normandie Niemen, case 312, 13397 Marseille Cedex 20, France b Laboratoire d'Oce Âanographie et de Bioge Âochimie UMR CNRS 6535, Centre d'Oce Âanologie de Marseille, 13288 Marseille, France Received 12 September 2000; accepted 18 October 2000 (returned to author for revision 5 October 2000) Abstract A surface sediment from Carteau cove, located at the western part of the Gulf of Fos (France), was collected and analysed to determine the lipid composition of its most polar fraction. Analyses by high performance liquid chroma- tography (HPLC) and thin-layer chromatography (TLC) of the polar fraction of the sediment extract revealed the presence of phospholipids (PL), with mainly phosphatidylglycerol (PG), phosphatidylethanolamine (PE) and lyso- phosphatidylethanolamine (LPE), but also the presence of non-phospholipid polar compounds (NPC). Phospholipids and non-phospholipid polar compounds (NPC) were isolated by preparative thin-layer chromatography and trans- methylated. Phospholipid ester-linked fatty acids ranged from 12- to 20-carbon atoms and accounted for 34.8 mgg 1 of dry sediment whereas fatty acids derived from non-phospholipid polar compounds ranged from 12- to 28-carbon atoms and accounted for 39.1 mgg 1 of dry sediment. The occurrence of signi®cant amounts of fatty acids derived from non-phospholipid polar compounds of a sediment polar fraction illustrates the importance of the preliminary analysis and puri®cation of phospholipids to avoid an overestimation of the microbial biomass when determined with a current phospholipid ester-linked fatty acids (PLFA) analysis. # 2001 Elsevier Science Ltd. All rights reserved. Keywords: Sediments; Phospholipids; Biomass; Microbial community; Phospholipid ester-linked fatty acids 1. Introduction Analyses of the phospholipid ester-linked fatty acids (PLFA) is an established method for estimating micro- bial biomass and community structure in marine sedi- ments (White et al., 1988). The major strength of the method is that fatty acids in intact phospholipids are mainly derived from living biomass since the polar group of phospholipids in dead organic matter is rapidly hydrolysed (White et al., 1979). A current PLFA analy- sis requires hydrolysis of phospholipids recovered by preparative liquid chromatography in the most polar fraction of the sediment extract, without any pre- liminary analysis of intact phospholipids. A recent report highlights the fact that the analysis of the head groups of phospholipids provides more information for bacterial characterisation than that provided by a sim- ple PLFA analysis (Fang et al., 2000). From this point of view, the present investigation focuses on the analysis of the most polar fraction of a marine sediment col- lected in Carteau cove (Gulf of Fos, France) to deter- mine its phospholipid and PLFA compositions. 0146-6380/01/$ - see front matter # 2001 Elsevier Science Ltd. All rights reserved. PII: S0146-6380(00)00153-4 Organic Geochemistry 32 (2001) 193±197 www.elsevier.nl/locate/orggeochem * Corresponding author. E-mail address: aries1383@yahoo.com (E. Aries).