Anthony Ranchou-Peyruse

C. Mazière, M. Ranchou-Peyruse, M. Guignard, G. Pasquet, I. Moretti, W. Foucher, S. LeSimple, O. Lhote, P. Maurizot, J. Jeanpert, O. Monge, E. Deville, A. Battani, A. Ranchou-Peyruse

Hydrogen is an energy resource that has been used for billions of years by prokaryotes (bacteria and archaea). As early as the mid-1990s, researchers theorized the existence of lithoautotrophic microbial ecosystems cut off from photosynthesis and powered by the presence of hydrogen produced by geochemical reactions. Thanks to enzymes called hydrogenases, the ability of prokaryotes to produce or consume hydrogen is widespread in these two kingdoms of life. Long confined to deep underground ecosystems, a growing number of studies show that large quantities of so-called white hydrogen, produced at depth, can reach continental surface ecosystems. Does this hydrogen play a structuring role in the taxonomic diversity of these microbial communities? Sampling campaigns were carried out in Namibia (Fairy circle) and New Caledonia (Tiebaghi peridotite massif and several surface sites with natural hydrogen emanations). These sites were studied from the point of view of the taxonomic diversity of microbial communities (16S rRNA gene) in an attempt to understand the effect of varying hydrogen concentrations on their structure. As natural hydrogen emissions can be transient, one of the aims of these studies is to try to define biomarkers of the presence of these emanations.