Halomonas rituensis sp. nov. and Halomonas zhuhanensis sp. nov., isolated from natural salt marsh sediment on the Tibetan Plateau

Two novel Gram-stain-negative, aerobic and non-motile rods bacteria, designated TQ8S T and ZH2S T , were isolated from salt marsh sediment collected from the Tibetan Plateau. Strain TQ8S T was found to grow at 10–40 °C (optimum, 30 °C), pH 6.0–11.0 (optimum, pH 8.0–9.0) and in the presence of 2–12 % (w/v) NaCl (optimum, 6–8 %). Strain ZH2S T was found to grow at 15–40 °C (optimum, 30 °C), pH 7.0–10.0 (optimum pH 9.0) and in the presence of 2–10 % (w/v) NaCl (optimum, 4–6 %). Phylogenetic analysis based on the 16S rRNA gene sequences showed that strains TQ8S T and ZH2S T shared 99.07 % sequence similarity between each other and were affiliated with the genus Halomonas , sharing 97.48 % and 97.41 % of sequence similarity to their closest neighbour Halomonas sulfidaeris Esulfide1 T , respectively. DNA–DNA hybridization analyses showed 61.0 % relatedness between strains TQ8S T and ZH2S T . The average nucleotide identity and the average amino acid identity values between the two genomes were 92.33 and 92.84 %, respectively. The values between the two strains and their close phylogenetic relatives were all below 95 %. The major respiratory quinones of strain TQ8S T were Q-9 and Q-8, while that of ZH2S T was Q-9. The main fatty acids shared by the two strains were C 18 : 1  ω 6c and/or C 18 : 1  ω 7c, C 16 : 1  ω 6c and/or C 16 : 1  ω 7c, C 16 : 0 and C 12 : 0 3-OH. Strain ZH2S T can be distinguished from TQ8S T by a higher proportion of C 19 : 0 cyclo ω 8 c . The G+C content of the genomic DNA of strains TQ8S T and ZH2S T were 57.20 and 57.14 mol%, respectively. On the basis of phenotypic distinctiveness and phylogenetic divergence, the two isolates are considered to represent two novel species of the genus Halomonas , for which the names Halomonas rituensis sp. nov (type strain TQ8S T =KCTC 62530 T =CICC 24572 T ) and Halomonas zhuhanensis sp. nov (type strain ZH2S T =KCTC 62531 T =CICC 24505 T ) are proposed.