A Gram-staining-negative, strictly aerobic, long-rod shaped with no flagellum and yellow-pigmented bacterium designated strain ZXX205T, was isolated from the hadal seawater at the depth of 7500 m in the Mariana Trench, Pacific Ocean. Phylogenetic analysis based on 16S rRNA gene sequences placed strain ZXX205T within the genus Winogradskyella and strain ZXX205T was most closely related to Winogradskyella flava KCTC 52348T and Winogradskyella echinorum KCTC 22026T with 96.9 % and 96.6 % sequence similarity, respectively. The sequence similarities to all other type strains were 96.3 % or less, and to the type strain Winogradskyella thalassocola LMG 22492T was 94.1 %. Growth occurred in the presence of 0-9.0 % (w/v) NaCl (optimum 3.0 %), at 4-45 °C (optimum 28 °C) and pH 6.0-9.0 (optimum pH 7.5). The sole respiratory quinone was menaquinone 6 (MK-6). The dominant cellular fatty acids (>10 %) of strain ZXX205T were iso-C15 : 0, iso-C15 : 1 G, iso-C16 : 0 3-OH and iso-C16 : 0. The polar lipids profile contained predominantly phosphatidylethanolamine, four glycolipids, four unidentified aminolipids and three unidentified lipids. The genomic DNA G+C content was 35.5 %. The DNA-DNA relatedness (DDH) values between strain ZXX205T and the most closely related species Winogradskyella flava and Winogradskyella echinorum were 21.1 and 20.4 %, respectively. Based on polyphasic taxonomic analysis, strain ZXX205T is considered to represent a novel species in the genus Winogradskyella of the family Flavobacteriaceae, for which the name Winogradskyella ouciana is proposed. The type strain is ZXX205T (=MCCC 1K03851T=JCM 33665T).
Keywords: Mariana Trench; Winogradskyella ouciana sp. nov; hadal seawater.