Marmoricola caldifontis sp. nov., a novel actinobacterium isolated from a hot spring

A Gram-staining-positive, aerobic, non-motile, non-spore-forming and coccoid-shaped actinobacterial strain, designated YIM 730233^T, was isolated from a sediment sample, collected from a hot spring in Tibet, China. Colonies were brownish, circular, smooth and convex. Strain YIM 730233^T was able to grow in the temperature range of 20-50 °C, pH 6.5-8.0 and in the presence of up to 1.0 % (w/v) NaCl. A comparison of the 16S rRNA gene sequence of strain YIM 730233^T with sequences of type strains of most closely related species of Marmoricola showed highest sequence similarities to Marmoricola bigeumensis MSL-05^T (98.3%) and Marmoricola pocheonensis Gsoil 818^T (98.1%). The draft genome of strain YIM 730233^T had a size of 4 806 234 bp with a DNA G+C content of 72.1 mol%. The major fatty acids (>10 %) of strain YIM 730233^T mainly consisted of iso-C_16 : 0, anteiso-C_17 : 0 and C_18 : 1 ω9c, typical of the genus Marmoricola. Strain YIM 730233^T had LL-2,6-diaminopimelic acid as the diagnostic diamino acid in the cell wall. The predominant isoprenoid quinone was MK-8(H₄). The polar lipids were diphosphatidylglycerol, phosphatidylglycerol, unidentified phospholipids and an unidentified lipid. DNA-DNA hybridizations between strain YIM 730233^T and type strains of Marmoricola bigeumensis MSL-05^T and Marmoricola pocheonensis Gsoil 818^T resulted in similarity values of 21 and 19% respectively. Based on DNA-DNA hybridization results, together with the differentiating biochemical and chemotaxonomic features, showed that strain YIM 730233^T represents a novel Marmoricola species, for which the name Marmoricola caldifontis sp. nov. (type strain YIM 730233^T=KCTC 49192^T=CGMCC 4.7521^T), is proposed.