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 degrees 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 818T (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 omega 9c, 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(H-4). 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.