Roseibacterium beibuensis sp. nov., a novel member of roseobacter clade isolated from Beibu Gulf in the South China Sea.

A novel aerobic, bacteriochlorophyll-containing bacteria strain JLT1202r(T) was isolated from Beibu Gulf in the South China Sea. Cells were gram-negative, non-motile, and short-ovoid to rod-shaped with two narrower poles. Strain JLT1202r(T) formed circular, opaque, wine-red colonies, and grew optimally at 3-4 % NaCl, pH 7.5-8.0 and 28-30 °C. The strain was catalase, oxidase, ONPG, gelatin, and Voges-Proskauer test positive. In vivo absorption spectrum of bacteriochlorophyll a presented two peaks at 800 and 877 nm. The predominant cellular fatty acid was C(18:1) ω7c and significant amounts of C(16:0), C(18:0), C(10:0) 3-OH, C(16:0) 2-OH, and 11-methyl C(18:1) ω7c were present. Strain JLT1202r(T) contained Q-10 as the major respiratory quinone and the genomic DNA G+C content was 76.3 mol%. Phylogenetic analysis based on 16S rRNA gene sequences of various species with validly published names showed that strain JLT1202r(T) fell within the genus Roseibacterium, family Rhodobacteraceae, sharing the highest similarity with Roseibacterium elongatum OCh 323(T) (97.9 % similarity), followed by Dinoroseobacter shibae DFL 12(T) (95.4 % similarity). The phylogenetic distance of pufM genes between strain JLT1202r(T) and R. elongatum OCh 323(T) was 9.4 %, suggesting that strain JLT1202r(T) was distinct from the only strain of the genus Roseibacterium. Based on the variabilities of phylogenetic and phenotypic characteristics, strain JLT1202r(T) stands for a novel species of the genus Roseibacterium and the name R. beibuensis sp. nov. is proposed with JLT1202r(T) as the type strain (=JCM 18015(T) = CGMCC 1.10994(T)).