Rhodospirillum rubrum ATCC 11170
Rhodospirillum rubrum is the type strain for the Rhodospirillaceae and has been, and continues to be, the subject of a substantial amount of physiological and genetic analysis. It is widely distributed and is Gram negative, motile, and spiral shaped. It is capable of growth under a broad variety of conditions, including aerobically and anaerobically, under the latter conditions using fermentation or photosynthesis for the production of energy. Photoautotrophic growth also occurs. A range of genetic tools have been developed for the use in the organism. Areas of particular research interest have been nitrogen fixation, carbon monoxide oxidation, CO2 fixation, H2 production, the photosystem, and the ATP synthase.

The nitrogen fixation system is particularly well described, consisting of both a MoFe and an Fe-only nitrogenase. The system of post-translational regulation of nitrogenase activity is the best-understood example of reversible ADP-ribosylation as a regulatory system in any organism. This system responds to both nitrogen and energy status signals. R. rubrum is able to grow on CO as sole energy source and the CO oxidation system has been extremely well-analyzed genetically and biochemically, largely through DOE support. The structure of the CODH that lies at the heart of this system, together with analyses of its catalytic mechanism, provide a model for more complex CODHs of other organisms. The CO-oxidation regulon also contains a novel CO-sensing protein, CooA, that is becoming a paradigm for gas-sensors and transcriptional regulators.