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

Abstract

An obligate aerobic and bacteriochlorophyll a-containing bacterium, designated strain AI77T, 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 AI77T is a member of the genus Roseobacter and closely related to Roseobacter ponti MM-7T (97.8%), Roseobacter denitrificans OCh 114T (97.3%) and Roseobacter litoralis OCh 149T (97.3%). The G+C content of strain AI77T was 61.0 mol%. The average amino acid identity values of the genome in strain AI77T with those in R. denitrificans OCh 114T and R. litoralis OCh 149T were 73.26% (SD 16.46) and 72.63% (SD 16.76), respectively. The digital DNA–DNA hybridization values of strain AI77T with the type strains R. denitrificans OCh 114T and R. litoralis OCh 149T were 18.70 and 18.50%, respectively. The dominant fatty acids (>10% of total fatty acids) of AI77T were summed feature 8 (C18:1 ω7c and/or C18:1 ω6c) and saturated fatty acid C16:0. 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 AI77T represents a new species of the genus Roseobacter, for which we propose the name Roseobacter cerasinus sp. nov.; the type strain is AI77T (=DSM 110091T=NBRC 114115T).