Maribacter hydrothermalis sp. nov., Isolated from Shallow-Sea Hydrothermal Systems Off Kueishantao Island

A Gram-stain-negative, strictly aerobic, yellow-pigmented bacterial strain, designated as T28^T, was isolated from seawater of the shallow-sea hydrothermal system, Kueishantao Islet, Taiwan, China. Cells were oxidase-negative and catalase-positive rods without gliding motility. Growth was observed at 10-40 °C (optimum, 30 °C), at pH 5.0-8.0 (optimum, pH 6.0) and in the presence of 0-5% (w/v) NaCl (optimum, 2.5%). Strain T28^T contained menaquinone 6 as the only isoprenoid quinone. The main cellular fatty acids were iso-C_15:0, iso-C_15:1 G, and iso-C_17:03-OH, summed feature 3 (C_16:1ω7c/ω6c). Polar lipids contain diphosphatidylglycerol, phosphatidylethanolamine, two unidentified phospholipids, six unidentified lipids, an unidentified aminolipid, and one unidentified aminophospholipids. The genomic DNA G + C content was 34.4 mol%. The 16S rRNA gene sequence of strain T28^T shared highest similarity with Maribacter arcticus (97.7%). Phylogenetic analysis based on 16S rRNA gene sequences revealed that the strain T28^T belongs to the genus Maribacter. On the basis of phylogenetic data and several distinct phenotypic characteristics, strain T28^T represents a novel species, for which the name Maribacter hydrothermalis sp. nov. is proposed. The type strain is T28^T (=CGMCC 1.15788^T = JCM 31510^T).