sp. nov., a moderately thermophilic bacterium isolated from a hot spring.

The present study aimed to determine the taxonomic positions of strains designated R-5-52-3, R-5-33-5-1-2, R-5-48-2 and R-5-51-4 isolated from hot spring water samples. Cells of these strains were Gram-stain-negative, non-motile and rod-shaped. The strains shared highest 16S rRNA gene sequence similarity with KCTC 32020 (95.1%). Growth occurred at 28-55 °C, at pH 6-8 and with up to 3 % (w/v) NaCl. DNA fingerprinting, biochemical, phylogenetic and 16S rRNA gene sequence analyses suggested that R-5-52-3, R-5-33-5-1-2, R-5-48-2 and R-5-51-4 were different strains but belonged to the same species. Hence, R-5-52-3 was chosen for further analysis and R-5-33-5-1-2, R-5-48-2 and R-5-51-4 were considered as additional strains of this species. R-5-52-3 possessed Q-8 as the only quinone and iso-C, iso-C, C and iso-C as major fatty acids. The polar lipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, unidentified polar lipids and two unidentified phospholipids. The genomic G+C content was 71.6 mol%. Heat shock proteins (e.g. Hsp20, GroEL, DnaK and Clp ATPases) were noted in the R-5-52-3 genome, which could suggest its protection in the hot spring environment. Pan-genome analysis showed the number of singleton gene clusters among members varied. Average nucleotide identity (ANI) values between R-5-52-3, YIM 77520 and KCTC 32020 were 80.1-85.8 %, which were below the cut-off level (95-96 %) recommended as the ANI criterion for interspecies identity. Thus, based on the above results, strain R-5-52-3 represents a novel species of the genus , for which the name sp. nov. is proposed. The type strain is R-5-52-3 (=KCTC 72061=CGMCC 1.16678).