Description du projet
Comprendre l’équilibre métabolique de l’océan
Environ 98 % de la biomasse océanique est constituée de micro-organismes tels que le minuscule phytoplancton d’algues. Le rôle du phytoplancton dans la photosynthèse de la Terre est essentiel car il capture le dioxyde de carbone (CO2), ce qui permet à l’océan de libérer d’importantes ressources vivantes et du dioxygène (O2). En outre, il déclenche la respiration microbienne, qui est un processus métabolique fondamental pour contrebalancer la photosynthèse et rejetter le carbone organique sous forme de CO2. Les connaissances sur la respiration microbienne restent cependant limitées. Le projet BULLE, financé par l’UE, évaluera l’équilibre métabolique de l’océan entre la photosynthèse et la respiration en analysant l’évolution du rapport entre la production de CO2 et la consommation d’O2, ce qu’on appelle le «quotient respiratoire» (QR). Le projet appliquera des technologies et des méthodes innovantes pour examiner comment les caractéristiques chimiques des nutriments régulent le QR dans les cellules bactériennes et étudier les interconnexions entre le QR, la production primaire nette et les activités bactériennes.
Objectif
About 98% of the ocean’s biomass is composed of microorganisms like the tiny algae, phytoplankton. Tiny but mighty when it comes at capturing carbon dioxide (CO2). Phytoplankton acts for half of the Earth’s photosynthesis, allowing ocean’s to supply major living resources and dioxygen (O2). Microbial respiration is the other fundamental biological process that counterbalances photosynthesis and returns organic carbon back as CO2. Yet, despite ocean’s pivotal role in global climate, microbial respiration remains one of the least explored metabolic processes; so that, whether oligotrophic ocean is a net sink or source of CO2, is highly debated for the last 20 years. The BULLE project aims to evaluate the ocean’s metabolic balance between photosynthesis and respiration by looking at the production of CO2 evolved to that O2 consumed by marine bacteria, the so-called “respiratory quotient” (RQ). Limits of detection of biological CO2 production have left RQ measurements far behind the multitude of investigations of photosynthesis. BULLE will face these challenges using the most recent technologies. The project strongly relies on the multidisciplinary expertise I will share with my host lab to tackle this issue at both cellular and community level. Specifically, BULLE aims to (1) investigate how the chemical characteristics of nutrients (Fe and C) regulate the RQ in bacterial cells and (2) study the links between the RQ, net primary production and bacterial activities. An innovative aspect of BULLE is the implementation of continuous measurements of O2/N2 and pCO2 concentrations respiration, and the deployment of In Situ Oxygen Dynamic Autosampler (IODA) instrumentation in the coastal NW Mediterranean Sea. The training I will receive with BULLE will help me give my career a new direction from a lab expertise towards high resolution in situ observations. In return, I will transfer my experience in microbial metabolisms and radioisotopes tracking methods to the host team.
Champ scientifique
Programme(s)
Régime de financement
MSCA-IF - Marie Skłodowska-Curie Individual Fellowships (IF)Coordinateur
13284 Marseille
France