Jannaschia cystaugens sp nov., an Alexandrium (Dinophyceae) cyst formation-promoting bacterium from Hiroshima Bay, Japan

Heterotrophic bacteria isolated from water samples taken from Hiroshima Bay, Japan, and referred to as Alexandrium (Dinophyceae) cyst formation-promoting bacteria, were assigned to the Roseobacter-Sulfitobacter-Silicibacter group within the alpha-Proteobacteria on the basis of nearly complete 16S rRNA gene sequences. Phylogenetic analyses showed that two strains, CFPB-A9(T) and CFPB-A5, are closely related to each other and that their closest relative was Jannaschia helgolandensis (95.9% sequence similarity). These strains were Gram-negative, motile, obligately aerobic rods that required sodium ions and 2-7% sea salts for growth and did not produce bacteriochlorophyll a. Their optimal growth temperature was 25-30 degreesC. The strains had Q-10 as the dominant respiratory quinone. Primary cellular fatty acid in both strains was 18: 1 omega7c. The DNA G+C contents of strains CFPB-A9(T) and CFPB-A5 were 59.1 and 59-2 mol%, respectively. Based on physiological, biological, chemotaxonomic and phylogenetic data, the strains are considered to represent a novel species, Jannaschia cystaugens sp. nov., with type strain CFPB-A9(T) (=LMG 22015(T)=NBRC 100362(T)).