Thermohahella caldifontis gen. nov., sp. nov., a thermo-halophilic bacterium isolated from a hot spring

A novel Gram-stain-negative, motile and thermo-halophilic rod-shaped bacterium SMD15-11^T was isolated from Seokmodo hot spring in Incheon, Republic of Korea. The strain grew at concentrations of 0.5-7% (w/v) NaCl (optimum at 3%), at pH 5.0-9.0 (optimum at 7.0) and in a temperature range of 30-60 °C (optimum at 50 °C). Strain SMD15-11^T shared the highest 16S rRNA gene sequence percentage with Hahella chejuensis 96CJ10356^T (92.5%). Both the phylogenetic and phylogenomic analyses showed that strain SMD15-11^T clustered with Hahellaceae members, demonstrating its close relatedness to the type species of the Hahellaceae family. The genome-relatedness indices between strain SMD15-11^T and other type species of the family Hahellaceae were in the ranges of 67.2-69.1% for average nucleotide identity, 59.3-62.8% for average amino acid identity and 15.9-24.8% for digital DNA-DNA hybridization, which were significantly below the cut-off values for the genus delineation. The genome comprised 3,444,746 bp with a G+C content of 60.1 mol%. The polar lipids contained phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol, four unidentified phospholipids, two unidentified aminophospholipids and two unidentified lipids. The predominant fatty acids are C_16:1  ω9c, C_16:0, C_18:1  ω9c and summed feature 3, comprising C_16:1  ω7c/C_16: 1  ω6c. The polyphasic taxonomic properties indicate that the strain represents a novel genus and species in the family Hahellaceae for which the name Thermohahella caldifontis gen. nov., sp. nov. is proposed. The type strain is SMD15-11^T (=KCTC 8289^T=NBRC 116488^T).