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 190^T, 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 190^T 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 190^T was 48.7 mol% based on the genome sequence. The comparison of 16S rRNA gene sequence similarities showed that strain 190^T was closely related to Alteromonas oceani S35^T (99.6 % sequence similarity), A. lipolytica JW12^T (98.2 %), A. aestuariivivens JDTF-113^T (97.7 %) and A. mediterranea DE^T (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 190^T 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 190^T and A. oceani S35^T and A. lipolytica JW12^T 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 190^T is clearly distinct from recognized species of the genus Alteromonas. On the basis of these features, we propose that strain 190^T (=MCCC 1K03456^T=KCTC 62227^T) represents a novel species of the genus Alteromonas with the name Alteromonas alba sp. nov.