Cupriavidus metallidurans strain CH34 (renamed from Ralstonia metallidurans and previously known as Ralstonia eutropha and Alcaligenes eutrophus) is a non-spore-forming, Gram-negative bacterium which is adapted to survive several forms of heavy metal stress. Therefore, it is an ideal subject to study heavy metal disturbance of cellular processes. This bacterium shows a unique combination of advantages not present in this form in other bacteria.
- Its genome has been fully sequenced (preliminary, annotated sequence data were obtained from the DOE Joint Genome Institute)
- It is not pathogenic, therefore, models of the cell can also be tested in artificial environments similar to its natural habitats.
- It is related to the plant pathogen Ralstonia solanacearum.
- It is of ecological importance since related bacteria are predominant in mesophilic heavy metal-contaminated environments.
- It is of industrial importance and used for heavy metal remediation and sensing.
- It is an aerobic chemolithoautotroph, facultatively able to grow in a mineral salts medium in the presence of H2, O2, and CO2 without an organic carbon source. The energy-providing subsystem of the cell under these conditions is composed only of the hydrogenase, the respiratory chain, and the F1F0-ATPase. This keeps this subsystem simple and clearly separated from the anabolic subsystems that starts with the Calvin cycle for CO2-fixation.
- It is able to degrade xenobiotics even in the presence of high heavy metal concentrations.
- Finally, strain CH34 is adapted to the outlined harsh conditions by a multitude of heavy-metal resistance systems that are encoded by the two indigenous megaplasmids pMOL28 and pMOL30 on the bacterial chromosome(s).
Also it plays a vital role, together with the species Delftia acidovorans, in the formation of gold nuggets, by precipitating metallic gold from a solution of gold(III) chloride, a compound highly toxic to most other microorganisms.