Sunxiuqinia elliptica gen. nov., sp. nov., a member of the phylum Bacteroidetes isolated from sediment in a sea cucumber farm

Three novel aerobic, elliptic bacteria, designated DQHS4T, DQHS8 and DQHS15, were isolated from sediment of a seashore pond for sea cucumber culture in Jimo, Qingdao, on the east coast of China. Cells were Gram-, oxidase- and catalase-negative. All three strains grew at 15–42 °C, pH 5–9 and NaCl concentrations between 0.5 and 10 %. DNA–DNA hybridization experiments revealed high (>85 %) relatedness among the three novel isolates and suggested that the strains constitute a single species. Comparative 16S rRNA gene sequence analysis indicated that these bacteria had less than 90 % similarity to all described species of the phylum Bacteroidetes; the closest relative of the three isolates was Prolixibacter bellariivorans F2T, sharing only 89.6 % sequence similarity. The major cellular fatty acids were iso-C17 : 0 3-OH (19.8–20.0 %), iso-C15 : 0 (16.9–17.3 %), anteiso-C17 : 1 B and/or iso-C17 : 1 I (7.4–8.7 %), C17 : 0 2-OH (8.4 %), anteiso-C15 : 0 (8.2–8.6 %) and C17 : 1ω6c (5.6–6.0 %). The major respiratory quinone was menaquinone-7 (MK-7) and the DNA G+C content was 41.8–43.5 mol%. Based on the distinct phylogenetic position and the combination of genotypic, phenotypic and chemotaxonomic characteristics, these three strains were considered to represent a novel species of a new genus in the phylum Bacteroidetes, for which the name Sunxiuqinia elliptica gen. nov., sp. nov. is proposed. The type strain of Sunxiuqinia elliptica is DQHS4T ( = CGMCC 1.9156T = NCCB 100301T = LMG 25367T).