Petrothermobacter organivorans gen. nov., sp. nov., a thermophilic, strictly anaerobic bacterium of the phylum Deferribacteres isolated from a deep subsurface oil reservoir

A novel thermophilic, anaerobic, chemoheterotrophic, acetate-oxidizing and iron(III)-, manganese(IV)-, nitrate- and sulfate-reducing bacterium, designated strain ANA T , was isolated from a deep subsurface oil field in Japan (Yabase oil field, Akita Pref.). Cells of strain ANA T were Gram-stain-negative, non-motile, non-spore forming and slightly curved or twisted rods (1.5-5.0 µm long and 0.6-0.7 µm wide). The isolate grew at 25-60 °C (optimum 55 °C) and pH 6.0-8.0 (optimum pH 7.0). The isolate was capable of reducing iron(III), manganese(IV), nitrate and sulfate as an electron acceptor. The isolate utilized a limited range of electron donors such as acetate, lactate, pyruvate and yeast extract for iron reduction. Strain ANA T also used pyruvate, fumarate, succinate, malate, yeast extract and peptone for fermentative growth. The major respiratory quinones were menaquinone-7(H8) and menaquinone-8. The strain contained C18 : 0, iso-C18 : 0 and C16 : 0 as the major cellular fatty acids. The G+C content of the genomic DNA was 34.3 mol%. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain ANA T was closely related to Calditerrivibrio nitroreducens in the phylum Deferribacteres with low sequence similarities (89.5 %), and formed a distinct clade within the family Deferribacteraceae. In addition, the isolate is the first sulfate-reducing member of the phylum Deferribacteres. Based on phenotypic, chemotaxonomic and phylogenetic properties, a novel genus and species, Petrothermobacter organivorans gen. nov., sp. nov., is proposed for the isolate (type strain=ANA T = NBRC 112621 T =DSM 105015 T ).