Sediminimonas qiaohouensis gen. nov., sp. nov., a member of the Roseobacter clade in the order Rhodobacterales

Abstract

Two aerobic bacterial strains, YIM B024(T) and YIM B025, were isolated from a salt mine in Yunnan, south-west China. Both strains showed almost the same physiological properties. Cells were Gram-negative, non-motile, non-spore-forming rods. The novel strains grew at 15-37 degrees C, pH 6.5-9.0 and 0.25-20 % (w/v) NaCl; optimum growth was observed at 28-30 degrees C, pH 7.0-8.5 and 1.5-10 % NaCl. Oxidase, catalase and nitrate-reducing activities were detected. The two strains were closely related to each other with a 16S rRNA gene sequence similarity of 100 %. DNA-DNA hybridization experiments revealed high relatedness values (90+/-0.4 %) between strains YIM B024(T) and YIM B025, which suggested that these two new strains constituted a single species. Phylogenetic analysis based on 16S rRNA gene sequences indicated that the two isolates formed a loose cluster with members of the genus Roseivivax in the Roseobacter clade, but were clearly separated from this genus. The levels of 16S rRNA gene sequence similarity between the two isolates and members of the genus Roseivivax ranged from 92.4 to 93.9 %. The major polar lipids comprised diphosphatidylglycerol, phosphatidylglycerol, phosphatidylcholine and four unknown phospholipids. The major cellular fatty acids were C(18 : 1)omega7c, C(16 : 0), C(18 : 1)omega9c, 11-methyl C(18 : 1)omega7c and C(19 : 0) cyclo omega8c. The sole respiratory quinone was Q-10 and the genomic DNA G+C content was 63.0-64.1 mol%. The distinct phylogenetic position and a combination of phenotypic and chemotaxonomic characteristics supported the proposal of the new isolates as representing a novel species in a new genus, for which the name Sediminimonas qiaohouensis gen. nov., sp. nov. is proposed. The type strain of the type species is YIM B024(T) (=KCTC 22349(T)=CCTCC AA 208033(T)).