A novel Gram-stain-negative, non-flagellated, non-motile, rod-shaped (0.4-0.6×1.8-2.5 µm), aerobic bacterial strain, designated JLT21T, was isolated from seawater of a shallow-sea hydrothermal system. Growth occurred with 0-4.0 % (w/v) NaCl (optimum, 2.0 % NaCl), at 8-45 °C (optimum, 25 °C) and at pH 3.0-10.0 (optimum, pH 7.0). Analysis of 16S rRNA gene sequences revealed that strain JLT21T showed the highest 16S rRNA gene sequence similarity to Gaetbulibacter aquiaggeris KEM-8T (97.2 %), Gaetbulibacter marinus IMCC1914T (96.9 %) and Yeosuana aromativorans GW1-1T (96.9 %). Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain JLT21T clustered with Y. aromativorans GW1-1T. The predominant respiratory quinone of strain JLT21T was menaquinone-6 (MK-6). Polar lipids were phosphatidylcholine, phosphatidylglycerol, phosphatidylethanolamine, three unidentified glycolipids and four unidentified lipids. The major fatty acids of strain JLT21T were iso-C15 : 0 (21.7 %), C16 : 1 ω6c/ω7c (11.5 %) and iso-C17 : 0 3-OH (10.9 %). The DNA G+C content of strain JLT21T was 32.6 %. On the basis of polyphasic analysis, strain JLT21T is considered to represent a novel species of the genus Yeosuana, for which the name Yeosuana marina sp. nov. is proposed. The type strain of Yeosuana marina is JLT21T (=CGMCC 1.15787T=JCM 31511T). The study helps us better understand the bacterial species in the shallow-sea hydrothermal system and their adaptations to the hydrothermal environment.
Keywords: Yeosuana; Yeosuana marina; phylogenetic analysis; shallow-sea hydrothermal system.