Affiliation:
1. Centre for Deep Sea Research, University of Bergen, Bergen, Norway
2. Department of Earth Science, University of Bergen, Bergen, Norway
3. Department of Biological Sciences, University of Bergen, Bergen, Norway
4. Computational Biology Unit, University of Berge, Bergen, Norway
Abstract
ABSTRACT
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,
Ghiorsea
spp., likely produce tubular iron oxide sheaths dominating the Fe mats at Fåvne, as observed via microscopy. With these structures,
Ghiorsea
may provide a surface area for members of other abundant taxa such as Campylobacterota, Gammaproteobacteria, and Alphaproteobacteria. Furthermore,
Ghiorsea
likely oxidizes both iron and hydrogen present in the fluids, with several
Ghiorsea
populations co-existing in the same niche. Homologs of Zetaproteobacteria Ni,Fe hydrogenases and iron oxidation gene
cyc2
were found in genomes of other community members, suggesting exchange of these genes could have happened in similar environments. Our study provides new insights into Zetaproteobacteria in hydrothermal vents, their diversity, energy metabolism and niche formation.
IMPORTANCE
Knowledge on microbial iron oxidation is important for understanding the cycling of iron, carbon, nitrogen, nutrients, and metals. The current study yields important insights into the niche sharing, diversification, and Fe(III) oxyhydroxide morphology of
Ghiorsea
, an iron- and hydrogen-oxidizing Zetaproteobacteria representative belonging to Zetaproteobacteria operational taxonomic unit 9. The study proposes that
Ghiorsea
exhibits a more extensive morphology of Fe(III) oxyhydroxide than previously observed. Overall, the results increase our knowledge on potential drivers of Zetaproteobacteria diversity in iron microbial mats and can eventually be used to develop strategies for the cultivation of sheath-forming Zetaproteobacteria.
Publisher
American Society for Microbiology
Subject
Computer Science Applications,Genetics,Molecular Biology,Modeling and Simulation,Ecology, Evolution, Behavior and Systematics,Biochemistry,Physiology,Microbiology