Marine Roseobacter Group Research Articles

Complete genome sequence of the Phaeobacter gallaeciensis type strain CIP 105210(T) (= DSM 26640(T) = BS107(T)).

Phaeobacter gallaeciensis CIP 105210T (= DSM 26640T = BS107T) is the type strain of the species Phaeobacter gallaeciensis. The genus Phaeobacter belongs to the marine Roseobacter group (Rhodobacteraceae, Alphaproteobacteria). Phaeobacter species are effective colonizers of marine surfaces, including frequent associations with eukaryotes. Strain BS107T was isolated from a rearing of the scallop Pecten maximus. Here we describe the features of this organism, together with the complete genome sequence, comprising eight circular replicons with a total of 4,448 genes. In addition to a high number of extrachromosomal replicons, the genome contains six genomic island and three putative prophage regions, as well as a hybrid between a plasmid and a circular phage. Phylogenomic analyses confirm previous results, which indicated that the originally reported P. gallaeciensis type-strain deposit DSM 17395 belongs to P. inhibens and that CIP 105210T (= DSM 26640T) is the sole genome-sequenced representative of P. gallaeciensis.

Linking a Bacterial Taxon to Sulfur Cycling in the Sea: Studies of the Marine Roseobacter Group

Evidence from culture-independent molecular studies indicate that members of the Roseobacter group are ubiquitous in marine environments, and bacteria in this taxon have now been isolated from and identified in systems as diverse as sea ice and coastal lagoons and as widespread as Antarctica and the Sargasso Sea. Because some members of this successful bacterial lineage are amenable to culturing, Roseobacter group isolates can be studied in the laboratory to reveal hints about potential ecological and biogeochemical roles. Initial studies of isolates suggested a widespread ability to degrade dimethylsulfoniopropionate (DMSP), an organic sulfur compound produced in abundance by marine algae. Further investigations revealed that some Roseobacter group isolates are able to carry out the major DMSP transformations that have been observed in natural bacterial communities from seawater. These include two competing pathways for DMSP degradation that may ultimately regulate the flux of organic sulfur (in the form of dimethylsulfide) from the surface ocean to the atmosphere, and a pathway for incorporation of the sulfur moiety of DMSP into bacterial protein. Recent field studies reinforce laboratory results, and demonstrate that members of the Roseobacter group may be one of the bacterial taxa linked to DMSP dynamics in the surface ocean.