Ruixingdingia sedimenti gen. nov., sp. nov., a novel taxon within the family Paracoccaceae isolated from sediment of Qiantang River.

A Gram-stain-negative bacterium, designated LG-4 ^T , was isolated from sediment of Qiantang River in Zhejiang Province, PR China. Cells were strictly aerobic, non-spore-forming, non-motile and short-rod-shaped (1.0-1.2 µm long and 0.7-0.8 µm wide). Growth occurred at 15-42 °C (optimum, 30 °C), at pH 5.0-9.0 (pH 7.0) and at 0-2.0 % (w/v) NaCl (optimum, 0.5 % NaCl). Strain LG-4 ^T showed 95.75-96.90 % 16S rRNA gene sequence similarity to various type strains of the genera Tabrizicola , Pseudotabrizicola , Phaeovulum , Rhodobacter and Wagnerdoeblera of the family Paracoccaceae , and the most closely related strain was Tabrizicola soli ZQBW ^T (96.90 % similarity). The phylogenomic tree showed that strain LG-4 ^T clustered in the family Paracoccaceae and was positioned outside of the clade composed of the genera Wagnerdoeblera and Falsigemmobacter . The average nucleotide identity and digital DNA-DNA hybridization values between strain LG-4 ^T and the related type strains were in the range of 74.19-77.56 % and 16.70-25.80 %, respectively. The average amino acid identity (AAI) values between strain LG-4 ^T and related type strains of the family Paracoccaceae were 60.94-69.73 %, which are below the genus boundary (70 %). The evolutionary distance (ED) values between LG-4 ^T and the related genera of the family Paracoccaceae were 0.21-0.34, which are within the recommended standard (≥0.21-0.23) for defining a novel genus in the family Paracoccaceae . The predominant cellular fatty acids were C _18 : 1  ω7 c , C _19 : 0 cyclo ω8 c , C _18 : 0 and C _16 : 0 , the isoprenoid quinone was Q-10, and the major polar lipids were phospholipid, phosphatidylglycerol, phosphatidylcholine, aminolipid and two unknown polar lipids. The genome size was 4.7 Mb with 68.6 mol% G+C content. On the basis of distinct phylogenetic relationships, low AAI values and high ED values, and differential phenotypic, physiological and biochemical characteristics, strain LG-4 ^T represents a novel species of a new genus in the family Paracoccaceae , for which the name Ruixingdingia sedimenti gen. nov., sp. nov. is proposed. The type strain is LG-4 ^T (=MCCC 1K08849 ^T =KCTC 8136 ^T ).