Marine lipids
A biomarker approach applied
to the microbial loop in the Mediterranean
surface waters: fatty acid composition
of bacteria and protozoa
L. Méjanelle
(1) , J. Laureillard
(1) , F. Rassoulzadeganv
(1) , A. Saliot
(1)
(1) Université de Paris 6, laboratoire de physique et chimie marines,
case 134, 4 place Jussieu, 75252 Paris Cedex 05, France - mejanel@ccr.jussieu.fr
(2) Observatoire océanographique de Villefranche-sur-Mer, BP 28,
06230 Villefranche-sur-Mer, France
In oceanic, coastal and estuarine waters, bacteria are controlled by grazing
of small heterotrophic flagellates, in turn consumed by ciliates, themselves of a suitable size for copepod predation. In oligotrophic waters,
this microbial loop dominares over other food webs in the recycling of
organic carbon and nitrogen.
Marine lipids of phytoplankton, zooplankton, bacteria, and vascular
plants have been rather extensively studied by geochemists, but little
attention has been paid to lipids of flagellates and ciliates. This is most
likely due to difficulties in isolating these small and fragile heterotrophs.
In order to apprehend their lipid composition, we realised cultures of
bacteria and heterotrophic protists. Bacteria and nanoflagellates from
oligotrophic waters out of Villefranche Bay were grown in 5 liter cultures
and cell abundances were surveyed by epifluorescence microscopy.
Cultures of bacterivorous ciliates were also realised. Lipids extracted
from bacteria, flagellates and ciliates were separated in lipid classes by
preparative thin-layer chromatography and fatty acids of structural
and reserve lipids were analysed by GC and GC/MS. Characteristic
patterns could be observecl within lipid composition of bacteria and
flagellates. Only lipid traces could be detected from ciliate cultures. No
bacterial imprint could be evidenced in reserve lipids of bacteriophages.
Results are discussed in relation to culture conditions and to potential
identification of biomarkers of the microbial loop members.
102
A biomarker approach applied
to the microbial loop in the Mediterranean
surface waters: fatty acid composition
of bacteria and protozoa
L. Méjanelle
(1) , J. Laureillard
(1) , F. Rassoulzadeganv
(1) , A. Saliot
(1)
(1) Université de Paris 6, laboratoire de physique et chimie marines,
case 134, 4 place Jussieu, 75252 Paris Cedex 05, France - mejanel@ccr.jussieu.fr
(2) Observatoire océanographique de Villefranche-sur-Mer, BP 28,
06230 Villefranche-sur-Mer, France
In oceanic, coastal and estuarine waters, bacteria are controlled by grazing
of small heterotrophic flagellates, in turn consumed by ciliates, themselves of a suitable size for copepod predation. In oligotrophic waters,
this microbial loop dominares over other food webs in the recycling of
organic carbon and nitrogen.
Marine lipids of phytoplankton, zooplankton, bacteria, and vascular
plants have been rather extensively studied by geochemists, but little
attention has been paid to lipids of flagellates and ciliates. This is most
likely due to difficulties in isolating these small and fragile heterotrophs.
In order to apprehend their lipid composition, we realised cultures of
bacteria and heterotrophic protists. Bacteria and nanoflagellates from
oligotrophic waters out of Villefranche Bay were grown in 5 liter cultures
and cell abundances were surveyed by epifluorescence microscopy.
Cultures of bacterivorous ciliates were also realised. Lipids extracted
from bacteria, flagellates and ciliates were separated in lipid classes by
preparative thin-layer chromatography and fatty acids of structural
and reserve lipids were analysed by GC and GC/MS. Characteristic
patterns could be observecl within lipid composition of bacteria and
flagellates. Only lipid traces could be detected from ciliate cultures. No
bacterial imprint could be evidenced in reserve lipids of bacteriophages.
Results are discussed in relation to culture conditions and to potential
identification of biomarkers of the microbial loop members.
102