Genome-based classification of F5 (=DSM 105917=JCM 32255) as sp. nov.

The genus has three validated species, , and , all of which were isolated from Vulcano island, Italy. They are obligately chemolithotrophic, aerobic, acidophilic and halophilic in nature and use either ferrous iron or reduced sulphur as electron donors. Recently, a novel strain was isolated from an acidic, saline drain in the Yilgarn region of Western Australia. Strain F5 has an absolute requirement for sodium chloride (>5 mM) and is osmophilic, growing in elevated concentrations (>1 M) of magnesium sulphate. A defining feature of its physiology is its ability to catalyse the oxidative dissolution of the most abundant copper mineral, chalcopyrite, suggesting a potential role in biomining. Originally categorized as a strain of , 16S rRNA gene phylogeny and multiprotein phylogenies derived from clusters of orthologous proteins (COGS) of ribosomal protein families and universal protein families unambiguously demonstrate that strain F5 forms a well-supported separate branch as a sister clade to and is clearly distinguishable from DSM 14175 and DSM14174. Results of comparisons between strain F5 and the other species, using genome-based average nucleotide identity, average amino acid identity, correlation indices of tetra-nucleotide signatures (Tetra) and genome-to-genome distance (digital DNA-DNA hybridization), support the contention that strain F5 represents a novel species of the genus . It is proposed that strain F5 should be formally reclassified as F5 (=DSM 105917=JCM 32255).