A thermophilic, anaerobic, chemolithoautotrophic bacterium (designated strain SL50T) was isolated from a hydrothermal sample collected at the Mid-Atlantic Ridge from the deepest of the known World ocean hydrothermal fields, Ashadze field (1 ° 58′ 21″ N 4 ° 51′ 47″ W) at a depth of 4100 m. Cells of strain SL50T were motile, straight to bent rods with one polar flagellum, 0.5–0.6 μm in width and 3.0–3.5 μm in length. The temperature range for growth was 25–75 °C, with an optimum at 60 °C. The pH range for growth was 5.0–7.5, with an optimum at pH 6.5. Growth of strain SL50T was observed at NaCl concentrations ranging from 1.0 to 6.0 % (w/v) with an optimum at 2.5 % (w/v). The generation time under optimal growth conditions for strain SL50T was 60 min. Strain SL50T used molecular hydrogen, acetate, lactate, succinate, pyruvate and complex proteinaceous compounds as electron donors, and Fe(III), Mn(IV), nitrate or elemental sulfur as electron acceptors. The G+C content of the DNA of strain SL50T was 28.7 mol%. 16S rRNA gene sequence analysis revealed that the closest relative of strain SL50T was Deferribacter abyssi JRT (95.5 % similarity). On the basis of its physiological properties and phylogenetic analyses, the isolate is considered to represent a novel species, for which the name Deferribacter autotrophicus sp. nov. is proposed. The type strain is SL50T (=DSM 21529T=VKPM B-10097T). Deferribacter autotrophicus sp. nov. is the first described deep-sea bacterium capable of chemolithoautotrophic growth using molecular hydrogen as an electron donor and ferric iron as electron acceptor and CO2 as the carbon source.
A Gram-positive, non-motile, spherical, red-pigmented and facultatively anaerobic bacterium, designated strain I-0T, was isolated from a sand sample of the Gobi desert in Xinjiang Autonomous Region, China. Phylogenetic analysis based on 16S rRNA gene sequences indicated that this isolate represents a novel member of the genus Deinococcus, with low sequence similarities (<94 %) to recognized Deinococcus species. The major cellular fatty acids were C16 : 1 ω7c and C16 : 0. Its polar lipid profile contained several unidentified glycolipids, phosphoglycolipids, phospholipids, pigments and an aminophospholipid. The peptidoglycan type was Orn–Gly2 (A3β) and the predominant respiratory quinone was MK-8. The DNA G+C content was 65.4 mol%. DNA–DNA relatedness between strain I-0T and Deinococcus radiodurans ACCC 10492T was 37 %. The strain was shown to be extremely resistant to gamma radiation (>15 kGy) and UV light (>600 J m−2). On the basis of the phylogenetic, chemotaxonomic and phenotypic data presented, strain I-0T represents a novel species of the genus Deinococcus, for which the name Deinococcus gobiensis sp. nov. is proposed. The type strain is I-0T (=DSM 21396T =CGMCC 1.7299T).