Putative novel hydrogen- and iron-oxidizing sheath-producing Zetaproteobacteria thrive at the Fåvne deep-sea hydrothermal vent field.

Iron-oxidizing Zetaproteobacteria are well known to colonize deep-sea hydrothermal vent fields around the world where iron-rich fluids are discharged into oxic seawater. How inter-field and intra-field differences in geochemistry influence the diversity of Zetaproteobacteria, however, remains largely unknown. Here, we characterize Zetaproteobacteria phylogenomic diversity, metabolic potential, and morphologies of the iron oxides they form, with a focus on the recently discovered Fåvne vent field. Located along the Mohns ridge in the Arctic, this vent field is a unique study site with vent fluids containing both iron and hydrogen with thick iron microbial mats (Fe mats) covering porously venting high-temperature (227-267°C) black smoker chimneys. Through genome-resolved metagenomics, we demonstrate that Zetaproteobacteria,