gen. nov., sp. nov.: a novel species of a novel genus in the family , isolated from the sediment of a tidal flat located in Zhoushan, China.

A Gram-stain-negative, aerobic and rod-shaped bacterium, designated as HZG-20, was isolated from a tidal flat in Zhoushan, Zhejiang Province, China. The 16S rRNA sequence similarities between strain HZG-20 and RR4-56, NNCM2, P31 and X9-2-2 were 98.9, 91.7, 91.0 and 91.0%, respectively. Colonies of strain HZG-20 were 1.4 mm in diameter, milky white, round, smooth and convex after cultivating on marine agar at 30 °C for 48 h. Cells were catalase and oxidase-negative. Growth occurred at 15-37 ℃ (optimum, 28 ℃), pH 5.0-9.0 (optimum, pH 6.0-8.0) and with 0-8% (w/v) NaCl (optimum, 1-3%). It contained Menaquinone-8 (H) as the sole respiratory quinone, and C (11.8-13.6%), C c (6.8-13.3%) and C anteiso (10.9-27.7%) as the major cellular fatty acids. The main polar lipids were diphosphatidylglycerol, phosphatidylethanolamine, one unidentified phospholipid, one unidentified aminolipid, one unidentified phosphoglycolipid, two unidentified glycolipids (GL1-GL2) and three unidentified lipids (L1-L3). The genome of strain HZG-20 was 3 835 886 bp in length, comprised 3746 protein-coding genes, with DNA G+C content of 67.1 mol%. The phylogenetic and phylogenomic trees indicated that strain HZG-20 formed an independent and stable clade with RR4-56. However, the average nucleotide identity, DNA-DNA hybridization and average amino acid identity values between strain HZG-20 and RR4-56, NNCM2, P31 and X9-2-2 were 81.6, 71.1, 68.7 and 69.5%; 23.0, 18.5, 17.9 and 17.5%; and 78.2, 56.8, 56.5 and 61.9%, respectively, together with distinct chemotaxonomic features, indicating strain HZG-20 should not be assigned to known genera. As a result, a novel species of a novel genus within the family , designated as gen. nov., sp. nov., was proposed. The type strain is HZG-20 (MCCC 1K08468=KCTC 82692).