The role members of the Roseobacter lineage play in marine biogeochemical cycles and climate change cannot be overestimated.
In term of its application, Roseobacter clade produces bioactive compounds, has been used widely in aquaculture and quorum sensing.
[4] Members of Roseobacter clade display diverse physiologies, and are commonly found to be either free living, particle associated, or in commensal relationships with marine phytoplankton, invertebrates, and vertebrates.
[5] Roseobacter are similar to phytoplankton in that both of them colonize surfaces, scavenge iron and produce bioactive secondary metabolites.
Genome plasticity could be a reason to explain the diversity and adaptability of Roseobacters, which is supported by the high number of probably conjugative plasmids.
[6] Comparison and analyzation of genomes of Roseobacter clade organisms is important because it can give insight into horizontal gene transfer and specific adaptation processes.
The Roseobacter clade has immense diversity of metabolic proficiency and regulatory circuits, which can be credited to their prosperity in a vast number of marine ecosystems.
In these coastal ecosystems, the Roseobacter clade interact with phytoplankton, macro algae and various marine animals living both mutualistic and pathogenic life styles.
It was suggested that the genome expansion was most likely due to new ecological habitats provided by the rise of eukaryotic phytoplankton groups like the dinoflagellates and coccolithophorids.
[8] This theory is backed up by the fact that modern lineages of Roseobacters are abundant components of the phycosphere of these two phytoplankton groups.
All dinoflagellates, coccolithophorids and diatoms are red-plastid-lineage phytoplankton, and the coincidence of the red-plastid radiation and Roseobacter genome innovation is consistent with adaptive evolution.
A recent study obtained four uncultivated roseobacters from surface waters of the North Pacific, South Atlantic, and Gulf of Maine.
The diversity makes an impact in ecology because of the roles that bacterial lineages play in oceanic elemental cycles, and their connections with marine eukaryotes.
[8] The Roseobacter clade represents up to 20% of bacterial cells in certain coastal areas and 3 to 5% in open ocean surface waters.
[9] Largely expanding amounts of genus and species characterizations in the clade shows the physiological and genetic diversity of these organisms.
Because of its large proportion in the total microbial community, the Roseobacter clade are major contributors to global CO2 fixation.
Non-phototrophic members can be used for CO oxidation, while AAPs can conduct CO2 fixation as Roseobacters can generate energy through aerobic anoxygenic photosynthesis.
[10] Roseobacter has the ability to degrade dimethylsulfoniopropionate (DMSP), an organic sulfur compound produced in abundance by marine algae.
In the members of the Roseobacter clade, Acyl-homoserine lactone (AHL)-based quorum sensing is widespread: over 80% of available Roseobacterial genomes encode at least one luxI homologue.
[21] This shows the significant role of QS controlled regulatory pathways plays in adapting to the relevant marine environments.
Among all the available Roseobacterial AHL-based QS, three are most well studied: Phaeobacter inhibens DSM17395, the marine sponge symbiont Ruegeria sp.