Geobacter uraniireducens

Geobacter uraniireducens (more recently known as Geotalea uraniireducens^[4]) is a gram-negative, rod-shaped, anaerobic, chemolithotrophic,^[5] mesophilic, and motile bacterium from the genus of Geobacter.^[1][2][6][7] G. uraniireducens has been found to reduce iron and uranium^[8][7][9] in sediment and soil.^[5] It is being studied for use in bioremediation projects due to its ability to reduce uranium and arsenic.^{[10][11][12][13]}

Geobacter uraniireducens
Scientific classification
Domain:	Bacteria
Phylum:	Pseudomonadota
Class:	Deltaproteobacteria
Order:	Desulfuromonadales
Family:	Geobacteraceae
Genus:	Geobacter
Species:	G. uraniireducens
Binomial name
Geobacter uraniireducens Shelobolina et al. 2008[1][2]
Type strain
ATCC BAA-1134, JCM 13001, Rf4[3]
Synonyms
Geotalea uraniireducens (Shelobolina et al. 2008) Waite et al. 2020

History

Geobacter uraniireducens was isolated from the subsurface sediment of a previous uranium ore processing facility undergoing uranium bioremediation in 2002.^[12] This occurred during a field study by Robert Anderson and his associates at the Old Rifle in situ test plot area in Rifle, Colorado.^[12] Shelobolina et al. (2008) further described the strain Rf4^T[7] While Geobacter uraniireducens is the basonym, David Waite and associates reclassified it to the current preferred name, Geotalea uraniireducens in their 2020 paper.^[4]

Characteristics

G. uraniireducens are gram negative bacteria that are motile rods with rounded ends and two to four long lateral flagellum, as well as pili and vesicles.^[7]

Extracellular electron transport strategies

The strategy of G. uraniireducens for extracellular electron transport (EET) is to facilitate iron (Fe(III)) oxide reduction via the production of a soluble electron shuttle.^[14] It has been found that riboflavin mediates EET to reduce extracellular electron acceptors.^[15] This is important because unlike in most Geobacter species, where conductive pili are critical for effective reduction of extracellular electron acceptors, the pili of G. uraniireducens are not conductive.^[15]

Metabolic mechanisms

G. uraniireducens is an iron-reducing bacteria that uses acetate as an electron donor and reduces uranium (U(VI)).^[7] In addition to Fe(III), it is also able to use Mn(IV), anthraquinone-2,6-disulfonate, malate and fumarate as electron acceptors.^[7] As it uses Fe(III) oxide as the electron acceptor, it can oxidize acetate, lactate, pyruvate and ethanol as electron donors.^[7]

Applications

Bioremediation

G. uraniireducens have been used in bioremediation studies in situ to decontaminate groundwater containing high levels of uranium from previous activities.^[10][11][12] This process can be enhanced by using acetate to stimulate increased populations.^[12]

Environmental implications

One environmental implication of interest in G. uraniireducens is its arsenic (As(V)) reducing capabilities in subsurface sediments.^[13] This ability is proposed to be due to gene encoding for respiratory arsenate reductase.^[13]

See also

• List of bacterial orders
• List of bacteria genera