Laboratoire de Microbiologie Géochimie et Ecologie marine

TRANSVERSAL AXIS : "ORGANISM - ORGANIC MATTER INTERACTIONS IN THE OCEANS" Coordinators : F. Gilbert and F. Van Wambeke

1- Scientific Objectives/

Heterotrophic organisms are the driving force of the elemental recycling in the marine environment. In the oceans, the availability and the state (dissolved, particulate) of the elements are closely related to the organism activities (e.g., bacterial enzymatic activity).

In surficial sediments, biotic external factors such as bioturbation continuously modify the state of oxygenation and the bacterial activity rates. Among various abiotic external factors, light radiation is known to influence the molecular weight and the state of the organic compounds, but also to create molecular damages on proteins and intracellular DNA, thus modifying the bacterial growth rate.

In order to understand and model the organisms-OM interactions in the oceans, the aim of the Tranversal Axis is to promote the development of multidisciplinary works involving researchers of the three LMGEM research teams.

2- Granted projects (LMGEM Transversal Axis fund - 2004-05)/

 Modeling of the bacterial growth rate related to OM availabiliy (NE Atlantic POMME campaigns) - J-C. Poggiale (Team 3) and D. Lefevre (Team 2)

 Development of tools (fluorescent molecular probes) to assess bacterial ectoenzymatic activities at the cellular level - M. Goutx (Team 1) and F. van Wambeke (Team 2)

 Selectivity of long-chain alkenone bacterial degradation processes - JF. Rontani (Team 1) and P. Bonin (Team 2)

3- Granted projects (LMGEM Transversal Axis fund - 2005-06)/

 Effect of high pressure on bacterial dynamics involved in the degradation of hydrocarbons - C. Tamburini (Team 2) and V. Grossi (Team 1)

 Dynamics of the bacterial communities structure and hydrocarbon degradation in deep-sea bioturbated sediments - P. Cuny (Team 2), V. Grossi (Team 1) and G. Stora (Team 1)

 Effect of macrobenthos-induced redox oscillation on the nitrifying and denitrifying community structure dynamics in marine sediments - V. Michotey (Team 2) and F. Gilbert (Team 1)

4- Granted projects (LMGEM Transversal Axis fund - 2006-07)/

 Biotic and abiotic degradation of long-chain alkenones - JF. Rontani (Team 1) and P. Bonin (Team 2)

 Biuogeochemistry of marine sediments. Quantification of spatial heterogenity induced by bioturbation- L. Pischedda (Team 1) and AF. Yao (Team 3)

 Bacterial degradation under OM pulses : An experimental and model approach - D. Lefevre (Team 2) and collaborators (Team 1 ; Team 3)