RHOMEO

The oceans cover more than 70% of the surface of our planet, regulate climate and support biological and non-biological resources.

Micro-organisms are present at a concentration of one billion cells per litre and play a fundamental role in the biogeochemical cycles that shape our planet by recycling nutrients and ultimately influencing the climate on a global scale.

It has recently been shown that a large proportion of these micro-organisms are photoheterotrophic, that is to say capable of using light as a complement to their energy needs which also depends on other processes and, in particular, breathing organic carbon.

Proteorhodopsin bacteria (PR) are a group of very important photoheterotrophic bacteria.

They use lumino-dependent proton pumps to make use of light as an energy source. Despite its importance, the role of photoheterotrophy in oceanic carbon flow remains virtually unknown. RHOMEO is a collaborative project where the assessment of diversity and spatiotemporal dynamics of PR marine bacteria will be combined with physiological studies into photobioreactors targeting isolated strains.

Advanced molecular techniques will be used to determine the diversity of bacteria containing PR 3 at contrasting sites in the Mediterranean Sea, the English Channel and the Arctic Ocean.

Physiological studies benefit from using unique instruments (photobioreactors), as well as model microbial strains to assess the effects of light on the utilisation capacity of carbon by abundant organisms in the environment.