''Shewanella putrefaciens'' is a

Gram-negative Gram-negative bacteria are bacteria that, unlike gram-positive bacteria, do not retain the crystal violet stain used in the Gram staining method of bacterial differentiation. Their defining characteristic is that their cell envelope consists ...

pleomorphic

bacterium Bacteria (; : bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were among the ...

. It has been isolated from marine environments, as well as from anaerobic sandstone in the

Morrison Formation The Morrison Formation is a distinctive sequence of Upper Jurassic sedimentary rock found in the western United States which has been the most fertile source of dinosaur fossils in North America. It is composed of mudstone, sandstone, siltston ...

New Mexico New Mexico is a state in the Southwestern United States, Southwestern region of the United States. It is one of the Mountain States of the southern Rocky Mountains, sharing the Four Corners region with Utah, Colorado, and Arizona. It also ...

. ''S. putrefaciens'' is also a

facultative anaerobe A facultative anaerobic organism is an organism that makes ATP by aerobic respiration if oxygen is present, but is capable of switching to fermentation if oxygen is absent. Some examples of facultatively anaerobic bacteria are ''Staphylococcus' ...

with the ability to reduce

iron Iron is a chemical element; it has symbol Fe () and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, forming much of Earth's o ...

and

manganese Manganese is a chemical element; it has Symbol (chemistry), symbol Mn and atomic number 25. It is a hard, brittle, silvery metal, often found in minerals in combination with iron. Manganese was first isolated in the 1770s. It is a transition m ...

metabolically Metabolism (, from ''metabolē'', "change") is the set of life-sustaining chemical reactions in organisms. The three main functions of metabolism are: the conversion of the energy in food to energy available to run cellular processes; the c ...

; that is, it can use iron and manganese as the terminal

electron acceptor An electron acceptor is a chemical entity that accepts electrons transferred to it from another compound. Electron acceptors are oxidizing agents. The electron accepting power of an electron acceptor is measured by its redox potential. In the ...

in the

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

(in contrast to obligate aerobes which must use oxygen for this purpose). It is also one of the organisms associated with the odor of rotting fish, as it is a marine organism which produces

trimethylamine Trimethylamine (TMA) is an organic compound with the formula N(CH3)3. It is a trimethylated derivative of ammonia. TMA is widely used in industry. At higher concentrations it has an ammonia-like odor, and can cause necrosis of mucous membranes ...

(hence the species name putrefaciens, from

putrid Putrefaction is the fifth stage of death, following pallor mortis, livor mortis, algor mortis, and rigor mortis. This process references the breaking down of a body of an animal post-mortem. In broad terms, it can be viewed as the decomposi ...

). In both solid and liquid media, ''S. putrefaciens'' is often recognizable by its bright pink color. On solid media, the colonies are round, fast-growing, and pink. The organism is also fast-growing in liquid media, and there will give the liquid an overall pink hue. On blood agar plates, the colonies are typically convex and large, with a brown pigment, and cause “greening” of the agar around the colonies. ''S. putrefaciens'' are non-lactose fermenters on MacConkey agar. As with all ''Shewanella'', this organism produces

hydrogen sulfide Hydrogen sulfide is a chemical compound with the formula . It is a colorless chalcogen-hydride gas, and is toxic, corrosive, and flammable. Trace amounts in ambient atmosphere have a characteristic foul odor of rotten eggs. Swedish chemist ...

on TSI. Although it is very rare for it to act as a human pathogen, there have been cases of infections and bacteremia caused by ''S. putrefaciens''. ''Shewanella putrefaciens'' is one of several species that have been shown to derive energy by reducing U(VI) to U(IV), which is thought to be important in making uranium deposits. In fact, strain CN32 is very metabolically versatile and is capable of reducing metals, metalloids, and even radionuclides in place of oxygen during anaerobic growth. This is known to include (but is not necessarily limited to) Fe(III)→Fe(II), Mn(IV)→(via Mn(III) intermediate)→Mn(II), V(V)→V(IV), Tc(VII)→Tc(V/IV) and U(VI)→U(IV).

References

External links

*
Type strain of ''Shewanella putrefaciens'' at Bac''Dive'' - the Bacterial Diversity Metadatabase
Alteromonadales Bacteria described in 1986 {{Alteromonadales-stub

See also

References

External links