Thermomonas flagellata sp. nov. and Thermomonas alba sp. nov., two novel members of the phylum Pseudomonadota isolated from hot spring sediments

Two novel species, designated strains SYSU G04041^T and SYSU G04536^T, were isolated from hot spring sediments collected in Yunnan, PR China. Phenotypic and chemotaxonomic analyses, and whole-genome sequencing were used to determine the taxonomic positions of the candidate strains. Phylogenetic analysis using 16S rRNA gene sequence indicated that strain SYSU G04041^T showed the highest sequence similarity to Thermomonas haemolytica A50-7-3^T (97.5 %), and SYSU G04536^T showed the highest sequence similarity to Thermomonas hydrothermalis SGM-6^T (98.2 %). The strains could be differentiated from other species of the genus Thermomonas by their distinct phenotypic and genotypic characteristics. Cells of strains SYSU G04041^T and SYSU G04536^T were aerobic, motile and Gram-stain-negative. Growth both occurred optimally at 45 °C and pH 7.0 for SYSU G04041^T and SYSU G04536^T. In addition, the predominant respiratory quinone in both isolates was ubiquinone Q-8. The major fatty acids (>10 %) of strain SYSU G04041^T were C_{16 : 0}, iso-C_{15 : 0} and iso-C_{16 : 0}, while the major fatty acids (>10 %) of strain SYSU G04536^T were iso-C_{15 : 0} and iso-C_{16 : 0}. The main detected polar lipids in strains SYSU G04041^T and SYSU G04536^T included phosphatidylethanolamine, diphosphatidylglycerol and phosphatidylglycerol. The G+C contents of the genomic DNA of strains SYSU G04041^T and SYSU G04536^T based on draft genomic sequences were 72.5 and 68.3 %, respectively. On the basis of phenotypic, genotypic and phylogenetic data, strains SYSU G04041^T and SYSU G04536^T represent two novel species of the genus Thermomonas, for which the names Thermomonas flagellata sp. nov. and Thermomonas alba sp. nov. are proposed, with the type strains SYSU G04041^T (=CGMCC 1.19366^T=KCTC 92228^T) and SYSU G04536^T (=CGMCC 1.19367^T=KCTC 82839^T), respectively.