Cross-feeding between exoelectrogenic and fermentative microbes from a deep-sea hydrothermal vent in a hyperthermophilic microbial fuel cell.. ANOD-CAP2014

Deep-sea hydrothermal vents are extreme environments where microorganisms play a key role in the development of the biocenosis, which is based on a complex trophic chain. Here we report the interactions between fermentative and exoelectrogenic microorganisms from this ecosystem in hyperthermophilic conditions. A bioelectrochemical system at 80°C inoculated with hydrothermal chimney samples exhibited current production from 159 to 247 mA/m², specifically by direct production on acetate, pyruvate and H2 and indirect production on yeast extract and peptone through the production of H2 and acetate from fermentation. The microorganisms found in on-electrode communities were mainly affiliated to fermentative Thermococcales and Bacillales and to known exoelectrogenic Geoglobus species. Stabilization of the current produced over weeks of culture suggests a cycling in substrate production and consumption which most probably takes place in environmental conditions enabling extremophilic microbes to survive through biofilms in these harsh ecological niches.