Characterizing a new bacterium belonging to the genus Roseobacter.

A Gram-stain-negative, coccoid to oval shaped, non-motile and obligate aerobic bacterium, designated strain AI77T was isolated from seawater around a fish farm in Ainan city, located in Ehime prefecture, Japan. Phylogenetic analysis based on 16S rRNA gene sequence revealed that strain AI77T was 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%). Strain AI77T could produce photosynthetic pigments, i.e., bacteriochlorophyll a and spheroidenone even under aerobic condition. The G+C content of strain AI77T was 61.0 mol%. On the basis of genetic and phenotypic data obtained in this study, we concluded that strain AI77T represents a new species of the genus Roseobacter.