Shewanella putrefaciens
Encyclopedia
Shewanella putrefaciens is a Gram-negative
bacterium. It has been isolated from marine
environments, as well as from anaerobic sandstone in the Morrison formation in New Mexico. S. putrefaciens is also a facultative anaerobe with the ability to reduce
iron
and manganese
metabolically
; that is, it can use iron and manganese as the terminal electron acceptor
in the electron transport chain
(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
s (hence the species name putrefaciens, from putrid).
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.
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.
S. 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).
Gram-negative
Gram-negative bacteria are bacteria that do not retain crystal violet dye in the Gram staining protocol. In a Gram stain test, a counterstain is added after the crystal violet, coloring all Gram-negative bacteria with a red or pink color...
bacterium. It has been isolated from marine
Ocean
An ocean is a major body of saline water, and a principal component of the hydrosphere. Approximately 71% of the Earth's surface is covered by ocean, a continuous body of water that is customarily divided into several principal oceans and smaller seas.More than half of this area is over 3,000...
environments, as well as from anaerobic sandstone in the Morrison formation in New Mexico. S. putrefaciens is also a facultative anaerobe with the ability to reduce
Redox
Redox reactions describe all chemical reactions in which atoms have their oxidation state changed....
iron
Iron
Iron is a chemical element with the symbol Fe and atomic number 26. It is a metal in the first transition series. It is the most common element forming the planet Earth as a whole, forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust...
and manganese
Manganese
Manganese is a chemical element, designated by the symbol Mn. It has the atomic number 25. It is found as a free element in nature , and in many minerals...
metabolically
Metabolism
Metabolism is the set of chemical reactions that happen in the cells of living organisms to sustain life. These processes allow organisms to grow and reproduce, maintain their structures, and respond to their environments. Metabolism is usually divided into two categories...
; that is, it can use iron and manganese as the terminal electron acceptor
Electron acceptor
An electron acceptor is a chemical entity that accepts electrons transferred to it from another compound. It is an oxidizing agent that, by virtue of its accepting electrons, is itself reduced in the process....
in the electron transport chain
Electron transport chain
An electron transport chain couples electron transfer between an electron donor and an electron acceptor with the transfer of H+ ions across a membrane. The resulting electrochemical proton gradient is used to generate chemical energy in the form of adenosine triphosphate...
(in contrast to obligate aerobes
Aerobic organism
An aerobic organism or aerobe is an organism that can survive and grow in an oxygenated environment.Faculitative anaerobes grow and survive in an oxygenated environment and so do aerotolerant anaerobes.-Glucose:...
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
Trimethylamine is an organic compound with the formula N3. This colorless, hygroscopic, and flammable tertiary amine has a strong "fishy" odor in low concentrations and an ammonia-like odor at higher concentrations...
s (hence the species name putrefaciens, from putrid).
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.
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.
S. putrefaciens is one of several species that have been shown to derive energy by reducing U
Uranium
Uranium is a silvery-white metallic chemical element in the actinide series of the periodic table, with atomic number 92. It is assigned the chemical symbol U. A uranium atom has 92 protons and 92 electrons, of which 6 are valence electrons...
(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).