Specific enrichment of hyperthermophilic electroactive Archaea from deep-sea hydrothermal vent on electrically conductive support

Guillaume Pillot, Eléonore Frouin, Emilie Pasero, Anne Godfroy, Yannick Combet-Blanc, Sylvain Davidson, Pierre-PolLiebgott

Aix Marseille Université, IRD, Université de Toulon, CNRS, MIO UM 110, Marseille, France.

Abstract

While more and more investigations are done to study hyperthermophilic exoelectrogenic communities from environments, none have been performed yet on deep-sea hydrothermal vent. Samples of black smoker chimney from Rainbow site on the Atlantic mid-oceanic ridge have been harvested for enriching exoelectrogens in microbial electrolysis cells under hyperthermophilic (80 °C) condition. Two enrichments were performed in a BioElectrochemical System specially designed: one from direct inoculation of crushed chimney and the other one from inoculation of a pre-cultivation on iron (III) oxide. In both experiments, a current production was observed from 2.4 A/m2 to 5.8 A/m2 with a set anode potential of −0.110 V vs Ag/AgCl. Taxonomic affiliation of the exoelectrogen communities obtained on the electrode exhibited a specific enrichment of Archaea belonging to Thermococcales and Archeoglobales orders, even when both inocula were dominated by Bacteria.

Graphical abstract

Keywords: Hyperthermophilic exoelectrogens, Deep-sea hydrothermal vent, Microbial electrolysis cell, External electron transfer.