Thalassotalea marina sp. nov., isolated from a marine recirculating aquaculture system, reclassification of Thalassomonas eurytherma as Thalassotalea eurytherma comb. nov. and emended description of the genus Thalassotalea

A Gram-stain-negative, facultatively anaerobic bacterium, strain QBLM2T, was isolated from rearing water of a marine recirculating aquaculture system in Tianjin, China. Its taxonomic position was investigated through a polyphasic approach. Cells of strain QBLM2T were non-spore-forming rods, motile by means of a single polar flagellum. Positive for oxidase and catalase. Growth occurred at 15-40 °C (optimum 30 °C), at pH 6.5-10.5 (optimum pH 7.5-8.5) and in the presence of 0-5.0 % (w/v) NaCl (optimum 3 %). Phylogenetic analysis based on 16S rRNA gene sequences showed that strain QBLM2T formed a distinct lineage within the genus Thalassotalea and exhibited sequence similarities of 94.5-96.3 % to members of the genus Thalassotalea. The predominant fatty acids (>10 %) were C17 : 1ω8c and summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c). The major polar lipids were phosphatidylglycerol and phosphatidylethanolamine. Ubiquinone 8 (Q-8) was the major ubiquinone. The DNA G+C content was 37.1 mol%. Based on the data above, strain QBLM2T is considered to represent a novel species of the genus Thalassotalea, for which the name Thalassotalea marina sp. nov. is proposed. The type strain is QBLM2T ( = CGMCC 1.12814T = KCTC 42731T). Phylogenetic analyses indicated that Thalassomonas eurytherma Za6a-12T fell within the genus Thalassotalea, so it is reclassified as Thalassotalea eurytherma comb. nov. and the description of the genus Thalassotalea is emended.