Abstract

A strictly aerobic, non-motile, ovoid-shaped Alphaproteobacteria, designated strain JC2049T,was isolated from a tidal flat sediment sample. The results of 16S rRNA gene sequence analysis indicated that this isolate belonged to the genus Thalassobius, with a sequence similarity of 96.9-97.3% to other valid Thalassobius spp. The cells required 1-7% NaCl for growth (optimum 2%) and accumulated poly-β-hydroxybutyrate. Nitrite was reduced to nitrogen, but nitrate was not reduced to nitrite. No genetic potential for aerobic anoxygenic photosynthesis was detected. The primary isoprenoid quinone (Ubiquinone-10), predominant cellular fatty acids (C18:1ω7c, 11 methyl C18:1ω7c and C16:0) and DNA G+C content (61 mol%) were all consistent with the assignment of this isolate to the genus Thalassobius. Several phenotypic characteristics clearly distinguished our isolate from other Thalassobius species. The degree of genomic relatedness between strain JC2049T and other Thalassobius species was in a range of 20-43%. The polyphasic data presented in this study indicates that our isolate should be classified as a novel species within the genus Thalassobius. The name Thalassobius aestuarii sp. nov. is therefore proposed for this isolate; the type strain is JC2049T (= IMSNU 14011T = KCTC 12049T = DSM 15283T).

• Keywords: Thalassobius aestuarii; Roseobacter clade; Rhodobacteraceae; tidal flat; taxonomy