Description of Thalassotalea piscium gen. nov., sp. nov., isolated from flounder (Paralichthys olivaceus), reclassification of four species of the genus Thalassomonas as members of the genus Thalassotalea gen. nov. and emended description of the genus Thalassomonas

Abstract

A Gram-staining-negative, aerobic, rod-shaped bacterium, designated strain T202T, was isolated from the gill of a cultured flounder (Paralichthys olivaceus). Based on 16S rRNA gene sequence similarity, strain T202T was a member of the family Colwelliaceae and shared 93.32–96.58 % similarity with type strains of all members of the most closely related genus Thalassomonas . Phylogenetically, the isolate shared a root with the type strains of four marine species, Thalassomonas agariperforans M-M1T, Thalassomonas agarivorans TMA1T, Thalassomonas loyana CBMAI 722T and Thalassomonas ganghwensis JC2041T. Optimal growth occurred in the presence of 2–4 % (w/v) NaCl, at pH 7.0–8.0 and at 28 °C. Ubiquinone 8 (Q-8) was the predominant respiratory quinone. The major fatty acids were C16 : 0, summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c), C16 : 1ω9c and C17 : 1ω8c. The major polar lipids were phosphatidylethanolamine and phosphatidylglycerol. The DNA G+C content of strain T202T was 37 mol%. On the basis of polyphasic analysis, especially the phylogenetic relationships and the lower DNA G+C content, strain T202T is considered to represent a novel species in a new genus, for which the name Thalassotalea piscium gen. nov., sp. nov. is proposed. The type strain of Thalassotalea piscium is T202T ( = JCM 18590T = DSM 26287T = KCTC 32144T). Because Thalassomonas agariperforans M-M1T, Thalassomonas agarivorans TMA1T, Thalassomonas loyana CBMAI 722T and Thalassomonas ganghwensis JC2041T formed a phylogenetic group together with strain T202T that was clearly separated from other known strains of Thalassomonas , these four species are reclassified as members of the genus Thalassotalea as Thalassotalea agariperforans comb. nov. (type strain M-M1T = KCTC 23343T = CCUG 60020T), Thalassotalea agarivorans comb. nov. (type strain TMA1T = BCRC 17492T = JCM 13379T = DSM 19706T), Thalassotalea loyana comb. nov. (type strain CBMAI 722T = LMG 22536T) and Thalassotalea ganghwensis comb. nov. (type strain JC2041T = IMSNU 14005T = KCTC 12041T = DSM 15355T). The type species of the genus Thalassotalea is Thalassotalea ganghwensis gen. nov., comb. nov. An emended description of the genus Thalassomonas is also proposed.