Ponticaulis koreensis gen. nov., sp. nov., a new member of the family Hyphomonadaceae isolated from seawater.

An obligately halophilic, stalked bacterium, designated strain GSW-23(T), was isolated from seawater that had been collected on the coast of Jeju, Korea. Cells of the strain were characteristically Gram-negative, aerobic, chemo-organotrophic, non-budding, motile rods or vibrioids that possessed prosthecae and holdfasts. Multiplication occurred by means of binary fission. The major ubiquinone was Q-10. The dominant cellular fatty acids were summed feature 7 (one or more of C(18 : 1)omega9c, C(18 : 1)omega12t and C(18 : 1)omega7c; 37.1 %), C(16 : 0) (25.5 %) and C(18 : 0) (14.1 %). The DNA G+C content was 53.3 mol%. 16S rRNA gene sequence analyses showed that the organism was related to members of the family Hyphomonadaceae and formed a distinct clade between members of the genus Hyphomonas and Hirschia baltica DSM 5838(T). Strain GSW-23(T) was most closely related to the genus Hyphomonas (92.5-93.9 % sequence similarity), but differed from members of the genus by reproduction by binary fission, some physiological properties (gelatin liquefaction and tolerance of 6 % NaCl) and chemotaxonomic features (major fatty acids, major quinones and DNA G+C content). The other genera of the family can be readily differentiated from the isolate by a battery of cultural, physiological and chemotaxonomic characteristics. On the basis of the phenotypic and phylogenetic data presented here, strain GSW-23(T) represents a novel genus and species in the family Hyphomonadaceae, for which the name Ponticaulis koreensis gen. nov., sp. nov. is proposed. The type strain of Ponticaulis koreensis is strain GSW-23(T) (=KCTC 22146(T) =DSM 19734(T) =JCM 14975(T)).