Dinoroseobacter shibae gen. nov., sp. nov., a new aerobic phototrophic bacterium isolated from dinoflagellates

1 GBF – Gesellschaft für Biotechnologische Forschung, Mascheroder Weg 1, D-38124 Braunschweig, Germany 2 DSMZ – Deutsche Sammlung von Mikroorganismen und Zellkulturen, Mascheroder Weg 1b, D-38124 Braunschweig, Germany 3 Institute of Microbiology & Institute of Physical Biology, Opatovicky mlyn, CZ-379 81 Trebon, Czech Republic Correspondence Irene Wagner-Döbler iwd{at}gbf.de A novel group of aerobic anoxygenic phototrophic bacteria was isolated from marine dinoflagellates, and two strains were characterized in detail. Cells were Gram-negative cocci or ovoid rods and were motile by means of a single, polarly inserted flagellum. They were obligate aerobes requiring 1–7 % salinity. The optimal pH range for growth was 6·5–9·0 and the temperature optimum was 33 °C. The bacteria contained bacteriochlorophyll a and spheroidenone as the only carotenoid. The in vivo absorption spectrum displayed two maxima in the infrared region at 804 and 868 nm. The distinct 804 nm band indicates the presence of light-harvesting system 2. Various organic carbon sources were assimilated, including many carboxylic acids, glucose and glycerol, but not butyrate, ethanol or methanol. Dissimilatory nitrate reduction was found for both strains. The physiological characteristics of the new strains resembled those of Roseobacter denitrificans , but there were differences in the lipid composition. Based on 16S rRNA gene sequence analysis the new strains are relatively distant from other recognized species, with the closest relatives Jannaschia helgolandensis , Ruegeria atlantica and Rhodobacter veldkampii showing 94·1–93·4 % similarity. Similarity to Roseobacter denitrificans was only 92·2 %, in line with numerous other species of the Roseobacter group. Therefore, it is proposed to classify the strains in a new genus and species within the Roseobacter clade, Dinoroseobacter shibae gen. nov., sp. nov. The type strain is DFL 12 T (=DSM 16493 T =NCIMB 14021 T ). Abbreviations: AAP, aerobic anoxygenic phototroph Published online ahead of print on 14 January 2005 as DOI 10.1099/ijs.0.63511-0. This paper is dedicated to Professor Norbert Pfennig on the occasion of his 80th birthday. The GenBank/EMBL/DDBJ accession number for the 16S rRNA gene sequence of strain DFL 12 T is AJ534211 . A phase-contrast micrograph of cells of strain DFL 12 T , plus graphs of temperature and pH dependence for growth of the two strains are available as supplementary figures in IJSEM Online.