Alteromonas alba sp. nov., a marine bacterium isolated from seawater of the West Pacific Ocean.

ABSTRACT

A Gram-stain-negative, strictly aerobic, motile by one polar flagellum, non-spore-forming, rod-shaped bacterium, designated as 190T, was isolated from seawater of the West Pacific Ocean and subjected to a polyphasic taxonomic investigation. Colonies were 1.0-2.0 mm in diameter, smooth, circular, convex and white after growth on marine agar at 30 °C for 24 h. Strain 190T was found to grow at 4-40 °C (optimum, 30 °C), at pH 5.5-10.5 (optimum, pH 6.5) and with 0.5-12.5 % (w/v) NaCl (optimum, 2.0 %). Chemotaxonomic analysis showed the sole respiratory quinone was ubiquinone 8 (Q-8), and the major fatty acids were summed feature 3 (C16  1ω7c and/or iso-C15  0 2-OH), C16  0 and summed feature 8 (C18  1ω6c and/or C18  1ω7c). The major polar lipids were phosphatidylethanolamine (PE), phosphatidylglycerol (PG), one unidentified aminolipid (AL1) and two unidentified glycolipids (GL1, GL2). The DNA G+C content of strain 190T was 48.7 mol% based on the genome sequence. The comparison of 16S rRNA gene sequence similarities showed that strain 190T was closely related to Alteromonas oceani S35T (99.6 % sequence similarity), A. lipolytica JW12T (98.2 %), A. aestuariivivens JDTF-113T (97.7 %) and A. mediterranea DET (97.5 %); it exhibited 97.0 % or less sequence similarity with the type strains of other species with validly published names. Phylogenetic trees reconstructed with the neighbour-joining, maximum-parsimony and maximum-likelihood methods based on 16S rRNA gene sequences showed that strain 190T constituted a separate branch with A. oceani, A. confluentis, A. aestuariivivens and A. lipolytica in a clade of the genus Alteromonas. OrthoANI values between strain 190T and A. oceani S35T and A. lipolytica JW12T were 93.5 and 77.9 %, respectively, and in silico DNA-DNA hybridization values were 53.8 and 21.2 %, respectively. Differential phenotypic properties, together with phylogenetic distinctiveness, demonstrated that strain 190T is clearly distinct from recognized species of the genus Alteromonas. On the basis of these features, we propose that strain 190T (=MCCC 1K03456T=KCTC 62227T) represents a novel species of the genus Alteromonas with the name Alteromonas alba sp. nov.