Hyphobacterium vulgare gen. nov., sp nov., a novel alphaproteobacterium isolated from seawater

A Gram-stain-negative, aerobic, non-spore-forming, non-motile, oval to rod-shaped, prosthecate bacterium, designated strain WM6(T), was isolated from a seawater sample collected from the South China Sea at a depth of 150 m and subjected to a polyphasic taxonomic investigation. Cells of strain WM6(T) were approximately 0.5-0.6 mu m in width and 0.8-1.2 mu m in length, and colonies were smooth, circular, convex and whitish yellow. Strain WM6(T) was found to grow at 10-45 degrees C (optimum, 30 degrees C), at pH 6.5-9.0 (optimum, pH 7.5-8.5) and with 1-6% (w/v) NaCl (optimum, 1-2 %). Chemotaxonomic analysis showed the predominant respiratory quinone and the major fatty acid of strains WM6(T) were ubiquinone-10 and C-18:(1)omega 7c respectively. The polar lipids of strain WM6(T) were phosphatidylglycerol, glucuronopyranosyldiglyceride, monoglycosyldiglyceride, sulfoquinovosyl diacylglycerol, seven unknown glycolipids and two unknown lipids. The DNA G+C content of strain WM6(T) was determined to be 59.8 mol% by HPLC. 16S rRNA gene sequence similarities showed that strain WM6(T) was related most closely to the genus Maricaulis with a similarity range from 92.3 to 93.8 %. Phylogenetic trees reconstructed with the neighbour-joining and maximum-likelihood methods using MEGA and maximum-likelihood methods using ARB showed that strain WM6(T) constituted a separated branch in the family Hyphomonadaceae. Differential phenotypic properties, together with phylogenetic distinctiveness, demonstrated that strain WM6(T) is clearly distinct from any validly published genus. On the basis of these features, strain WM6(T) represents a novel species of a new genus with the name Hyphobacterium vulgare gen. nov., sp. nov. The type strain of Hyphobacterium vulgare is WM6(T) (= MCCC 1K03222(T) = KCTC 52487(T)).