Cupriavidus metallidurans strain CH34, (renamed from Ralstonia metallidurans^[1] and previously known as Ralstonia eutropha and Alcaligenes eutrophus^[2]) is a non-spore-forming Gram-negative bacterium which is adapted to survive several forms of heavy metal stress.^[3][4] 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, unnotated sequence data were obtained from the DOE Joint Genome Institute (JGI)).
• It is non-pathogenic, therefore, models of the cell can also be tested in artificial environments similar to the natural habitats of this bacterium.
• It is related to the plant pathogen Ralstonia solanacearum.^[5]
• It is of ecological importance since related bacteria are predominant in mesophilic heavy metal-contaminated environments.^[2][6]
• It is of industrial importance and used for heavy metal remediation and sensing.^[4]
• 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.^[7] 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.^[8]
• 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).^[3][4][9]

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) tetrachloride, a compound highly toxic to most other microorganisms.^{[10] [11] [12]}

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External links [edit]

• Article at Live Science