''Cupriavidus metallidurans'' is a non-spore-forming,

Gram-negative Gram-negative bacteria are bacteria that do not retain the crystal violet stain used in the Gram staining method of bacterial differentiation. They are characterized by their cell envelopes, which are composed of a thin peptidoglycan cell wall ...

bacterium which is adapted to survive several forms of heavy metal stress.

As a model and industrial system

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 In the fields of molecular biology and genetics, a genome is all the genetic information of an organism. It consists of nucleotide sequences of DNA (or RNA in RNA viruses). The nuclear genome includes protein-coding genes and non-coding ge ...

(strain CH34) has been fully sequenced (preliminary, annotated sequence data were obtained from the DOE

Joint Genome Institute The U.S. Department of Energy (DOE) Joint Genome Institute (JGI), first located in Walnut Creek then Berkeley, California, was created in 1997 to unite the expertise and resources in genome mapping, DNA sequencing, technology development, and i ...

) * 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 ''Ralstonia solanacearum'' is an aerobic non-spore-forming, Gram-negative, plant pathogenic bacterium. ''R. solanacearum'' is soil-borne and motile with a polar flagellar tuft. It colonises the xylem, causing bacterial wilt in a very wide rang ...

''. * It is of

ecological Ecology () is the study of the relationships between living organisms, including humans, and their physical environment. Ecology considers organisms at the individual, population, community, ecosystem, and biosphere level. Ecology overlaps wi ...

importance since related bacteria are predominant in

mesophilic A mesophile is an organism that grows best in moderate temperature, neither too hot nor too cold, with an optimum growth range from . The optimum growth temperature for these organisms is 37°C. The term is mainly applied to microorganisms. Organi ...

heavy metal-contaminated environments. * It is of industrial importance and used for heavy metal remediation and sensing. * It is an

aerobic Aerobic means "requiring air," in which "air" usually means oxygen. Aerobic may also refer to * Aerobic exercise, prolonged exercise of moderate intensity * Aerobics, a form of aerobic exercise * Aerobic respiration, the aerobic process of cellu ...

chemolithoautotroph A lithoautotroph is an organism which derives energy from reactions of reduced compounds of mineral (inorganic) origin. Two types of lithoautotrophs are distinguished by their energy source; photolithoautotrophs derive their energy from light while ...

, 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 A hydrogenase is an enzyme that catalyses the reversible oxidation of molecular hydrogen (H2), as shown below: Hydrogen uptake () is coupled to the reduction of electron acceptors such as oxygen, nitrate, sulfate, carbon dioxide (), and fumara ...

, the

respiratory chain An electron transport chain (ETC) is a series of protein complexes and other molecules that transfer electrons from electron donors to electron acceptors via redox reactions (both reduction and oxidation occurring simultaneously) and couples th ...

, and the F1F0-ATPase. This keeps this subsystem simple and clearly separated from the

anabolic Anabolism () is the set of metabolic pathways that construct molecules from smaller units. These reactions require energy, known also as an endergonic process. Anabolism is the building-up aspect of metabolism, whereas catabolism is the breaking-do ...

subsystems that starts with the

Calvin cycle The Calvin cycle, light-independent reactions, bio synthetic phase, dark reactions, or photosynthetic carbon reduction (PCR) cycle of photosynthesis is a series of chemical reactions that convert carbon dioxide and hydrogen-carrier compounds into ...

for CO₂-fixation. * It is able to degrade

xenobiotics A xenobiotic is a chemical substance found within an organism that is not naturally produced or expected to be present within the organism. It can also cover substances that are present in much higher concentrations than are usual. Natural compo ...

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).

Ecology

CSIRO ScienceImage 3908 Coloured scanning electron image of bacterioform gold on a gold grain from the Hit or Miss Mine in northern Queensland

''C. metallidurans'' plays a vital role, together with ''

Delftia acidovorans ''Delftia acidovorans'' is a Gram-negative, motile, non-sporulating, rod-shaped bacterium known for its ability to biomineralize gold and bioremediation characteristics. It was first isolated from soil in Delft, Netherlands. The bacterium was or ...

'', in the formation of

gold nugget :''"Gold nugget" may also refer to the catfish Baryancistrus xanthellus or the mango cultivar Gold Nugget.'' A gold nugget is a naturally occurring piece of native gold. Watercourses often concentrate nuggets and finer gold in placers. Nuggets a ...

s. It precipitates metallic gold from a solution of

gold(III) chloride Gold(III) chloride, traditionally called auric chloride, is a compound of gold and chlorine with the molecular formula . The "III" in the name indicates that the gold has an oxidation state of +3, typical for many gold compounds. Gold(III) c ...

, a compound highly toxic to most other microorganisms.The bacteria that turns toxic chemicals into pure gold

References

External links

Type strain of ''Cupriavidus metallidurans'' at Bac''Dive'' - the Bacterial Diversity Metadatabase
{{Taxonbar, from=Q136005 Burkholderiaceae Metallotolerants Bacteria described in 2001