Roseobacter cerasinus sp. nov., isolated from a fish farm

An obligate aerobic and bacteriochlorophyll a -containing bacterium, designated strain AI77 T , was isolated from a fish farm in Uwa Sea, Japan. Cells were Gram-stain-negative, coccoid- to oval-shaped, and showed no motility. Phylogenetic analysis based on the 16S rRNA gene sequences revealed that strain AI77 T is a member of the genus Roseobacter and closely related to Roseobacter ponti MM-7 T (97.8 %), Roseobacter denitrificans OCh 114 T (97.3 %) and Roseobacter litoralis OCh 149 T (97.3 %). The G+C content of strain AI77 T was 61.0 mol%. The average amino acid identity values of the genome in strain AI77 T with those in R. denitrificans OCh 114 T and R. litoralis OCh 149 T were 73.26 % (SD 16.46) and 72.63 % (SD 16.76), respectively. The digital DNA–DNA hybridization values of strain AI77 T with the type strains R. denitrificans OCh 114 T and R. litoralis OCh 149 T were 18.70 and 18.50 %, respectively. The dominant fatty acids (>10 % of total fatty acids) of AI77 T were summed feature 8 (C 18 : 1  ω7 c and/or C 18 : 1  ω6 c ) and saturated fatty acid C 16 : 0 . The sole respiratory quinone was ubiquinone-10. The predominant polar lipids were phosphatidylcholine, phosphatidylglycerol and diphosphatidylglycerol. Based on the genetic and phenotypic data obtained herein, we conclude that strain AI77 T represents a new species of the genus Roseobacter , for which we propose the name Roseobacter cerasinus sp. nov.; the type strain is AI77 T (=DSM 110091 T =NBRC 114115 T ).