Abstract
Chemolithoautotrophic Hydrogenovibrio are ubiquitous and abundant at hydrothermal vents. They can oxidize sulfur, hydrogen, or iron, but none are known to use all three energy sources. This ability though would be advantageous in vents hallmarked by highly dynamic environmental conditions. We isolated three Hydrogenovibrio strains from vents along the Indian Ridge, which grow on all three electron donors. We present transcriptomic data from strains grown on iron, hydrogen, or thiosulfate with respective oxidation and autotrophic carbon dioxide (CO2) fixation rates, RubisCO activity, SEM, and EDX. Maximum estimates of one strain's oxidation potential were 10, 24, and 952 mmol for iron, hydrogen, and thiosulfate oxidation and 0.3, 1, and 84 mmol CO2 fixation, respectively, per vent per hour indicating their relevance for element cycling in-situ. Several genes were up- or downregulated depending on the inorganic electron donor provided. Although no known genes of iron-oxidation were detected, upregulated transcripts suggested iron-acquisition and so far unknown iron-oxidation-pathways.