Microbial inhabitants of Prony’s chimneys

Abundant and diverse bacterial communities live inside the Prony hydrothermal chimneys connected with the anoxic, high pH and low salinity fluids. Some bacteria can be involved in the oxidation/consoumption of hydrogen released by the Prony springs, such as hydrogenotrophic deltaproteobacterial or betaproteobacterial species thriving in anoxic zones, or oxic/anoxic transition zones of the concretions, respectively). The low archaeal diversity was dominated by uncultured Methanosarcinales linked to methane production or oxidation, as observed in other serpentinization-driven submarine and subterrestrial ecosystems (e.g. Lost City, The Cedars). Hydrogen, methane and sulfur compounds appear as the energy driven forces of the microbial communities inhabiting the hyperalkaline Prony hydrothermal chimneys, indicating that serpentinization-related fluids can sustain chemosynthetic life in photic zone.

Novel anaerobic and alkaliphilic bacteria

Five novel anaerobic species belonging to the phylum Firmicutes were isolated by our team and characterized from the chimneys of the Prony Hydrothermal field. These species belong to the genera Alkaliphilus, Serpentinicella, and Acetoanaerobacterium. They are adapted to alkaline pH (pH 9-10) and they can fermente sugars, organic acids and aminoacids, in accordance with genome data.

Firmicutes as first colonizers of Prony hydrothermal chimneys

The study of the microbial diversity of the most juvenile parts of the active hydrothermal chimneys indicated a major role potentially played by bacteria belonging to the Firmicutes. They seem to be the first inhabitants of the hydrothermal chimneys, before the Methanosarcinales archaea. They could participate in the early construction of carbonated structures through organomineralization processes.

This project is funded by the French National research Agency « ANR ». It is an interdisciplinary and international long-terme collaboration between researchers at the Mediterranean Institute of Oceanography, Geoscience Environnement Toulouse, Institut du Globe de Paris, Medis, Entropie, The Stony Brook University.