The Metabolism of Thermophilic Hydrolytic Bacterium Thauera hydrothermalis Strain par-f-2 Isolated from the West Siberian Subsurface Biosphere

A novel moderately thermophilic, organotrophic bacterium, strain Par-f-2, was isolated from a sample of hot water emerging from a 2775 m-deep well in Western Siberia, Russia. Cells of the novel isolate were non-sporulating Gram-negative motile rods, often forming groups and aggregates. Strain Par-f-2 grew at 25–60°C, pH 6.0–9.5, and at NaCl concentration from 5 to 7 g L–1. The isolate is an aerobe capable of utilizing mono- and polysaccharides, yeast extract, and some organic acids and aminoacids as the carbon and energy sources. Microaerobic growth was observed. Elemental sulfur, sulfate, nitrate, fumarate, and arsenate were not reduced. The major fatty acids were C16:0 (69.7%) and C16:1ω7 (19.3%). The G+C content of the DNA was 63.5 mol%. 16S rRNA gene sequence-based phylogenetic analysis showed Thauera hydrothermalis (Betaproteobacteria) being its closest relative with 99.8% of 16S rRNA gene sequences identity. Strain Par-f-2 was deposited in the DSMZ and VKM (=DSM 26751=VKM V-2822).