Two novel Gram-stain negative, moderately thermophilic, aerobic, rod-shaped strains, designated 3D203T and 3D207, were isolated from hot spring sediment samples collected from Tibet, western China. Phylogenetic analyses based on 16S rRNA gene sequence similarities showed that two isolates belonged to the genus Microvirga and were most closely related to Microvirga makkahensis SV1470T (98.5% and 98.4%, respectively) and two strains had 99.8% similarity to each other. The average nucleotide identity (ANI) based on whole genome sequences of two strains and M. makkahensis SV1470T was 80.8% and 80.78%, respectively. Optimum growth was observed at 45 °C, pH 7.0 and 0.5% NaCl. They both could tolerate to high concentration arsenic. Ubiquinone 10 (Q10) was their predominant quinone. The differences of strains 3D203T and 3D207 were phosphatidyl dimethyl ethanolamine, phosphatidyl-N-methylethanolamine, phosphatidylglycerol, unidentified glycolipids and unidentified lipids. The major fatty acids (> 5%) were identified C18:1ω7c and/or C18:1ω6c, C18:0 and C16:0. The genomic DNA G + C contents of strain 3D203T and 3D207 based on whole genome sequences were 64.8% and 64.7%, respectively. Phenotypic, chemotaxonomic, phylogenetic and genomic analyses suggested that two strains represent a novel species of the genus Microvirga, for which the name Microvirga arsenatis sp. nov. is proposed. The type strain is 3D203T (= CGMCC 1.17691T = KCTC 72653T).
Keywords: ANI; Arsenical; Hot spring; Microvirga; Taxonomy.