Rhodobacteraceae

Rhodobacteraceae is a diverse family of Gram-negative bacteria within the order Rhodobacterales of the class Alphaproteobacteria, in the phylum Proteobacteria. It comprises numerous genera, including Rhodobacter, Loktanella, Phaeobacter, and Roseobacter, among others. Members are phenotypically varied, but many are small, motile rods or ovoid cells. A distinctive feature of a large subset is their ability to perform photosynthesis using bacteriochlorophyll a and carotenoids, enabling aerobic or microaerophilic, often anoxygenic photosynthesis; these phototrophic members are typically purple non-sulfur bacteria. Other members are chemoorganotrophs that respire organic substrates.

Ecologically, Rhodobacteraceae are widespread in aquatic environments, especially marine systems, where the Roseobacter lineage dominates coastal waters and participates in the degradation of organic matter and cycling of sulfur compounds. In marine environments, several genera metabolize dimethylsulfoniopropionate (DMSP) to dimethyl sulfide, contributing to the sulfur cycle. The family also includes bacteria associated with algae, sediments, and marine organisms, and some produce bioactive compounds, such as antibiotics or algicides; Phaeobacter species, for example, synthesize tropodithietic acid.

Taxonomic notes: Rhodobacteraceae is a large and phylogenetically diverse family. Ongoing genomic studies continue to refine genus boundaries and relationships, and some taxa have been reassigned as taxonomy of Alphaproteobacteria evolves.