Some strains of marine Synechococcus are capable of "chromatic acclimation", that is to modify their light-harvesting capacity to match the dominant color of their habitat. Thus, when grown in green light, these cyanobacteria can synthesize pigments that specifically catch this color, but when shifted to blue light they can, in less than a week, change their pigmentation to catch this new color. To harvest light, cyanobacteria use a sophisticated "antenna" (phycobilisomes) composed of a very complex assemblage of proteins and pigments. This is a modification in the pigment content of this antenna which allows these micro-organisms to adapt to changes in the ambient light color. 

In collaboration with three American teams, we have unveiled the molecular bases of this intriguing phenomenon (Shukla et al. 2012).  

In the Ocean, planktonic photosynthesis allows atmospheric carbon fixation and is accomplished by microscopic algae which are either eukaryotic or prokaryotic. Some Bacteria and Archaea (Cyanobacteria) can fix atmospheric nitrogen, which confers to them a competitive advantage in the central areas of the oceans that are devoid of nutrients. The paper by Anne W. Thompson, Rachel A. Foster, Andreas Krupke, Brandon J. Carter, Niculina Musat, Daniel Vaulot, Marcel MM Kuypers, & Jonathan P. Zehr published in Science on September 21, 2012 (download pdf) describes a new type of symbiosis between a cyanobacterium that can fix nitrogen and a eukaryotic alga belonging to the prymnesiophytes, which cannot fix it. The cyanobacterium provides nitrogen to the alga, but as it is lacking a part of the photosynthetic apparatus and cannot fix carbon, it relies on the Eukaryote to get the carbon it needs for its growth. This type of planktonic symbiosis has never been observed before and none of the two partners have been isolated in the laboratory. This discovery underscores the potential importance of such associations among plankton. In contrast to coral symbioses, planktonic symbioses have been very little studied until now but could have a strong impact of mineral fluxes in central regions of the oceans.

Nouvelles approches de mise en culture
du pico- et nano-phytoplancton marin
Sujet de Master 2 - Janvier-Juin 2013

Equipe d'accueil : Diversité du Plancton Océanique, UMR 7144, Roscoff

Encadrant : Daniel VAULOT et Ian PROBERT
UMR 7144 Station Biologique de Roscoff
29680 Roscoff - Tel : 02 98 29 25 64 mél : vaulot@sb-roscoff.fr

Le but de ce projet de Master est de développer de nouvelles approches pour l'isolement du phytoplancton marin afin d'obtenir des cultures représentatives du milieu océanique.  On testera d'une part des méthodes de préservation des échantillons afin de pouvoir effectuer les isolements au laboratoire plutôt que sur le terrain.  On développera d'autre part des approches basées sur le tri par cytométrie en flux et de nouvelles conditions de culture.  Les cultures isolées seront caractérisées génétiquement par séquençage du gène de l'ARNr 18S ainsi que d'autres marqueurs plus résolutifs (ITS).

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The three teams of the Plankton Group are participating in a new EU project called MicroB3 dedicated to the genomics and metagenomics of Marine Microbes. The startup meeting took place at Jacobs University in Bremen on Feb 1-3 2012.

The project’s main objectives are to create an integrative database, which is open to researchers worldwide and features many innovative tools for data analysis, and to develop a legal framework for genome-based environmental research. New biotechnological applications will also be identified.

32 partner institutions from 14 countries are participating in the project, which unites leading experts from eight disciplines and is coordinated by Frank Oliver Glöckner, Professor of Bioinformatics at Jacobs University.

Modern biotechnological processes, which utilize or modify genetic information, have been in use for many years. Their main areas of usage lie within agriculture, medical or pharmaceutical applications, and the food industry. The so-called “blue biotechnology”, which uses genetic information of marine organisms for biotechnology, is still considered new terrain: Only 1% of all biotechnology companies worldwide use marine ecosystem knowledge as a source (e.g. for innovative enzymatic functions).

The potential of blue biotechnology, however, is huge, since life in marine habitats and especially microbial communities shows an enormous biodiversity and thus a genetic diversity, which largely exceeds that of most terrestrial ecosystems. Yet, this diversity has hardly been explored.

Daniel Vaulot participated in the VII ECODIM Course in Las Cruces, Chile.  This marine microbiology course that takes place every two years is attended by the 15 best graduate and post-graduates from Latin America in the field.  This year Chile, Argentina, Brazil, Uruguay, Colombia and Cuba were represented.  The course lasts 3 weeks and includes lectures, field trips, practicals as well as team research project. This year it was a great success with impressive students.  See you for the next edition in 2014....

Anne-Claire Baudoux has been recruited in 2011 as a CNRS "Chargée de Recherche" and has started her new position in Roscoff on Oct 1, 2011. She is a member of the Diversity of Oceanic Plankton team, part of UMR 7144.

Anne-Claire's interest includes the diversity, the evolution, and the ecology of marine viruses, which infect phytoplankton and bacteria.  Her research focuses mainly on the interactions of viruses with their environment (both biotic and abiotic) and how these interactions affect the functioning of marine ecosystems.

A few years ago, Anne-Claire spent some times in Roscoff as a visiting post-doctoral fellow.

Publications of Anne-Claire