A Gram-stain-negative bacterium, designated strain IO390401T, was isolated from a seawater sample from the sulphide region of the Indian Ocean. Phylogenetic trees based on 16S rRNA gene sequences showed that strain IO390401T is a member of the genus Alteromonas, sharing 97.0-97.4 % 16S rRNA gene sequence similarity with Alteromonas additaR10SW13T, A. stellipolaris LMG 21861T, A. naphthalenivorans JCM 17741T, A. gracilis 9a2T and A. australica H17T, and 94.8-96.8 % with the type strains of other species of the genus Alteromonas. Strain IO390401T contained ubiquinone-8 (Q-8) as the sole isoprenoid quinone, C16:0 and C16:1ω7c/C16:1ω6c as the dominant cellular fatty acids, and phosphatidylglycerol and phosphatidylethanolamine as the major polar lipids. The genome of strain IO390401T consists of a 4.4 Mb chromosome with a G+C content of 48.2 mol%. Average nucleotide identity values between strain IO390401T and the three closest phylogenetic neighbours, namely A. additaR10SW13T, A. stellipolaris LMG 21861T and A. naphthalenivorans JCM 17741T, were 70.5, 70.4 and 70.6 %, respectively, and the corresponding in silico DNA-DNA hybridization values were 20.6, 20.7 and 21.1 %. Phylogenetic distinctiveness and chemotaxonomic differences, together with phenotypic properties determined in this study, revealed that strain IO390401T could be differentiated from closely related species. It is therefore proposed as representing a novel species in the genus Alteromonas, for which the name Alteromonas indica sp. nov. is suggested. The type strain is IO390401T (=JCM 32638T=CGMCC 1.13554T=CCTCC AB 2018072T).
Keywords: Alteromonadaceae; Alteromonadales; Alteromonas; Alteromonas indica; Gammaproteobacteria; taxonomy.