Blanc SVSE 7 - Blanc - SVSE 7 - Biodiversité, évolution, écologie et agronomie

ProteoRHOdopsin-containing prokaryotes in Marine EnvirOnments – RHOMEO

RHOMEO - ProteoRHOdopsin-containing prokaryotes in Marine EnvirOnments

RHOMEO is a collaborative project where estimates of diversity and spatio-temporal dynamics of marine Proteorhodopsin Containing Prokaryotes (PCPs) will be combined with physiological studies employing photobioreactors targeting isolated model strains.

Objectives

The overall objecive of the project is to gain significant insights on the role of marine photoheterotrophic bacteria in the ocean carbon cycle. We will first evaluate the contribution of photoheterotrophs to bacterial abundance and activity. The second objective of the project is to perform physiological studies to evaluate the impact of light on carbon process efficiency in PCPs

Sequencinh of proteorhodopsin- coding genes from different locations by new generation sequencing
Quantification of prevalent PR coding Genes by Real Time PCR
Chemostat (continuous culture) Experiments (Quantification of biomass and gene expression) to evaluate carbon utilization efficiency

L’étude de la diversité et de l’abondance des bactéries à protéorhodopsine en mer de We have finished a study of diversity and abundance of PCPs in the Beaufort Sea ( Arctic Ocean). We finished sampling at both planned sites (English Channel and Mediterranean) and performed Illumina sequencing of proteorhodopsin coding genes (the data are being subject to bioinformatic analysis). We have also performed experiments measuring carbon yields of the model strain Photobacterium angustum S14 and showed that increases of yield are possible but linked to non optimal conditions and a higher manintenance coefficient. We have submitted a manuscript associated with these results

We hope that a better understanding of the role of PCPs in the marine environment will allow for a better modeling of the carbon cycle taking in consideration (or not) these organisms and their eventual responses to global change

We have written/submitted three manuscripts from results of studies of diversity of PCPs in the Arctic Ocean and the physiology of P. angustum S14. Two thesis on the study of PCP have will shortly be defended

Manuscripts :
Boeuf, D., F. Humily & C. Jeanthon. Diversity of arctic pelagic prokaryotes with an emphasis on photoheterotrophic bacteria. (to be submitted to Biogeosciences special issue-deadline Dec. 2013)
Boeuf, D., R. Lami, E. Cunnington & C. Jeanthon. Proteorhodopsin-containing bacteria are active and abundant in the western Arctic Ocean. (to be submitted to Env. Microbiol.)
Courties, A. Riedel T., Rapaport, A, Nielsdottir M.C. Caparros, J., Catala, P, Salmeron, C., Batailler N., Lebaron, P., Suzuki, MT. Light-driven increases in carbon yield are linked to maintenance energy inthe proteorhodopsin-containing Photobacterium angustum S14, PNAS, in review

Thesis:
Bœuf, D. 2013. Importance écologique des bactéries photohétérotrophes dans l’Océan Arctique. Thèse de doctorat de l’Université Pierre et Marie Curie soutenue le 2 mai 2013, 352 pages.
Courties A. 2013. Les effets de la lumière sur le métabolisme du carbone des bactéries marines contenant la protéorhodopsine Thèse de doctorat de l’Université Pierre et Marie Curie soutenue le 18 décembre 2013.

The oceans cover more than 70% of the Earth’s surface, regulate its climate, and sustain living and nonliving resources. With about 1 billion cells per liter, microorganisms are fundamental to the biogeochemical cycles that shape our planet by cycling nutrients ultimately influencing climate on a global scale. A large proportion of these microorganisms have recently been shown to be photoheterotrophs, meaning they can use light to supplement energy requirements, that otherwise would depend on other processes, particularly organic carbon respiration. A group of photoheterotrophic organisms that is particularly abundant in the oceans are proteorhodopsin-containing prokaryotes (PCPs) that use light driven proton pumps to gather light energy as sources of cellular energy. However, despite its significance, the role of photoheterotrophy in the carbon budgets of the oceans is still unknown.
RHOMEO is a collaborative project where estimates of diversity and spatio-temporal dynamics of marine PCPs will be combined with physiological studies employing photobioreactors targeting isolated model strains. The overall objective is to gain significant insights on the role of marine proteorhodopsin containing prokaryotes in the ocean. We will apply state-of-the-art molecular techniques to determine the diversity of PCPs at three different sites in the Mediterranean Sea, English Channel and Arctic Ocean, representative of different trophic conditions.
Physiological studies will benefit from available unique instrumentation (photobioreactors), and model microbial strains to evaluate light effects in the efficiency of carbon utilization by environmentally abundant organisms. We will identify the PCP strains most appropriate to conduct physiological studies, and will estimate growth efficiency under varying light conditions, and substrate quality. These experiments will allow an estimation of "savings" in carbon respiration allowed by light energy.
Combining specific carbon utilization efficiencies to specific environmentally significant strains, the results of field and physiological studies will allow the estimation of the effects of light-driven metabolism in the budget of organic carbon in these marine sites. These results will have a very significant impact in furthering the understanding of the marine carbon cycle, and ultimately in understanding forecasts of future climate. Impacts of the project will be through training of graduate students, publications, and a workshop to be organized at the completion of the project.

Project coordinator

Monsieur Marcelino Suzuki (UNIVERSITE PARIS 6) – suzuki@obs-banyuls.fr

The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.

Partner

CNRS-SBR CENTRE NATIONAL DE LA RECHERCHE SCIENTIFIQUE - DELEGATION REGIONALE BRETAGNE ET PAYS- DE-LA-LOIRE
OOB UNIVERSITE PARIS 6

Help of the ANR 270,000 euros
Beginning and duration of the scientific project: January 2012 - 36 Months

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