A novel, moderately thermophilic, Gram-stain-negative bacterium, designated strain J18^T, was isolated from a water-flooded oil reservoir. Cells were aerobic, oxidase- and catalase-positive, with a polar flagellum. Growth occurred at 35-60 °C and at pH 6-8.5. The respiratory quinones were ubiquinone 8 and ubiquinone 9. The dominant cellular fatty acids were C_{16 : 0}, C_{17 : 0} cyclo, C_{19 : 0} cyclo ω8c and summed feature 8 (C_{18 : 1} ω7c/C_{18 : 1} ω6c). The polar lipids consisted of phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol, phosphatidylcholine, an unidentified aminolipid, an unidentified phospholipid and an unidentified aminophospholipid. The strain showed the highest 16S rRNA gene sequence similarities to Tepidiphilus margaritifer DSM 15129^T (98.6 %), Tepidiphilus succinatimandens DSM 15512^T (98.4 %) and Tepidiphilus thermophilus DSM 27220^T (98.1 %), respectively, and the similarity to other species was lower than 93 %. In the phylogenetic trees, it constituted a unique sub-cluster within the genus Tepidiphilus. The DNA G+C content of strain J18^T was 64.44 mol%. As compared with the type strains, the genome-to-genome distances of strain J18^T were 34.7-40 %. These results confirmed the separate species status of J18^T with its close relatives. On the basis of physiological, chemotaxonomic and phylogenetic analyses along with the low levels of identity at the whole-genome level, it can be concluded that strain J18^T represents a new species of the genus Tepidiphilus, for which the name Tepidiphilus olei sp. nov. is proposed. The type strain of T. olei is J18^T (=CGMCC 1.16800^T=LMG 31400^T).

Jian-Jie Shan

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