Fatty acids associated with the frustules of diatoms and their fate during degradation -- A case study in Thalassiosira weissflogii - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue Deep Sea Research Part I: Oceanographic Research Papers Année : 2014

Fatty acids associated with the frustules of diatoms and their fate during degradation -- A case study in Thalassiosira weissflogii

Résumé

Diatoms are major actors in the export of organic carbon out of the euphotic zone. Yet, the processes linking biogenic silica and carbon sedimentation fluxes to deep oceanic layers remain unclear. Analysing organic fractions in biominerals is challenging because efficient cleaning often led to structural alteration of organic molecules. Hence, although lipids are widely used as biogeochemical markers in ocean flux study, few studies have dealt with the lipids that are associated with frustules. In the present study, a protocol was set up to extract and quantify the fatty acids associated to the frustule of the diatom species Thalassiosira weissflogii. The protocol involves solvent extraction of diatom external lipids, followed by clean frustule dissolution by 4%NaOH during 1h at 95°C and subsequent solvent re-extraction of frustule-associated lipids. Results confirmed that this protocol was efficient first, to isolate the frustule from the rest of the cellular organic carbon and second to extract and quantify fatty acids (FA) associated to frustules of this species. FA composition of the frustules was significantly different from that of the whole cells consisting primarily of 14:0, 16:0 and 18:0 FA, as well as a smaller portion of 16:1 and 18:1 unsaturated FA. Frustule-associated FA constituted 7% of the total FA and 1.8% of the total POC. The 30 days T.weissflogii degradation/dissolution experiment suggested that frustule FA14:0 and 16:0 were mainly associated with the bSiO2 phase dissolving slowly as no degradation of this pool was measured despite 78% frustule dissolution. At the end of the degradation experiment, this pool constituted 5.8% of the remaining total POC suggesting an effective protection by the frustule through strong interaction with the biogenic silica which is consistent with the correlation observed at depth between Si and POC sedimentation fluxes.
Fichier principal
Vignette du fichier
20131206TEXT_FA_associated_with_the_frustule_of_diatoms_Suroy_et_al_DSRI.pdf (1.26 Mo) Télécharger le fichier
Origine : Fichiers produits par l'(les) auteur(s)
Loading...

Dates et versions

hal-01073211 , version 1 (09-10-2014)

Identifiants

Citer

Maxime Suroy, Brivaëla Moriceau, Julia Boutorh, Madeleine Goutx. Fatty acids associated with the frustules of diatoms and their fate during degradation -- A case study in Thalassiosira weissflogii. Deep Sea Research Part I: Oceanographic Research Papers, 2014, 86, pp.21-31. ⟨10.1016/j.dsr.2014.01.001⟩. ⟨hal-01073211⟩
494 Consultations
489 Téléchargements

Altmetric

Partager

Gmail Facebook X LinkedIn More