Desulfovulcanus ferrireducens gen. nov., sp. nov., a thermophilic autotrophic iron and sulfate-reducing bacterium from subseafloor basalt that grows on akaganeite and lepidocrocite minerals

A deep-sea thermophilic bacterium, strain Ax17(T), was isolated from 25 degrees C hydrothermal fluid at Axial Seamount. It was obligately anaerobic and autotrophic, oxidized molecular hydrogen and formate, and reduced synthetic nanophase Fe(III) (oxyhydr)oxide minerals, sulfate, sulfite, thiosulfate, and elemental sulfur for growth. It produced up to 20 mM Fe2+ when grown on ferrihydrite but < 5 mM Fe2+ when grown on akaganeite, lepidocrocite, hematite, and goethite. It was a straight to curved rod that grew at temperatures ranging from 35 to 70 degrees C (optimum 65 degrees C) and a minimum doubling time of 7.1 h, in the presence of 1.5-6% NaCl (optimum 3%) and pH 5-9 (optimum 8.0). Phylogenetic analysis based on 16S rRNA gene sequences indicated that the strain was 90-92% identical to other genera of the family Desulfonauticaceae in the phylum Pseudomonadota. The genome of Ax17(T) was sequenced, which yielded 2,585,834 bp and contained 2407 protein-coding sequences. Based on overall genome relatedness index analyses and its unique phenotypic characteristics, strain Ax17(T) is suggested to represent a novel genus and species, for which the name Desulfovulcanus ferrireducens is proposed. The type strain is Ax17(T) (= DSM 111878(T) = ATCC TSD-233(T)).

Automated summary

The deep-sea thermophilic bacterium Ax17(T) was isolated from hydrothermal fluid at Axial Seamount, exhibiting obligate anaerobic and autotrophic growth characteristics. It showed unique phenotypic and genotypic features, suggesting it represents a novel genus and species named Desulfovulcanus ferrireducens.