Robertkochia solimangrovi sp. nov., isolated from mangrove soil, and emended description of the genus Robertkochia

To date, there is sparse information for the genus Robertkochia with Robertkochia marina CC-AMO-30D(T) as the only described member. We report here a new species isolated from mangrove soil collected at Malaysia Tanjung Piai National Park and perform polyphasic characterization to determine its taxonomic position. Strain CL23(T) is a Gram-negative, yellow-pigmented, strictly aerobic, catalase-positive and oxidase-positive bacterium. The optimal growth conditions were determined to be at pH 7.0, 30–37 °C and in 1–2 % (w/v) NaCl. The major respiratory quinone was menaquinone-6 (MK-6) and the highly abundant polar lipids were four unidentified lipids, a phosphatidylethanolamine and two unidentified aminolipids. The 16S rRNA gene similarity between strain CL23(T) and R. marina CC-AMO-30D(T) is 96.67 %. Strain CL23(T) and R. marina CC-AMO-30D(T) clustered together and were distinguished from taxa of closely related genera in 16S rRNA gene phylogenetic analysis. Genome sequencing revealed that strain CL23(T) has a genome size of 4.4 Mbp and a G+C content of 40.72 mol%. Overall genome related indexes including digital DNA–DNA hybridization value and average nucleotide identity are 17.70 % and approximately 70%, below the cutoffs of 70 and 95%, respectively, indicated that strain CL23(T) is a distinct species from R. marina CC-AMO-30D(T). Collectively, based on the phenotypic, chemotaxonomic, phylogenetic and genomic evidences presented here, strain CL23(T) is proposed to represent a new species with the name Robertkochia solimangrovi sp. nov. (KCTC 72252(T)=LMG 31418(T)). An emended description of the genus Robertkochia is also proposed.