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=Assignment 3= Original- "Shewanella"

Diet
Shewanella species respire a variety of electrons acceptors in anoxic conditions, many of which are located extracellularly. The mechanism for extracellular electron transfer involves c-type cytochromes that span the inner and outer membranes and "bacterial nanowires".

Metabolism
Currently discovered Shewanella species are heterotrophic facultative anaerobes. In the absence of oxygen, members of this genus may use a variety of other electron acceptors for respiration. These include thiosulfate, sulfite, or elemental sulfur, as well as fumarate. Some members of this species, most notably Shewanella oneidensis, have the ability to respire extracellular insoluble manganese and iron oxides using bacterial nanowires. Some of the more unique modes of respiration are being studied for their potentially useful applications. The metal respiring capabilities can potentially be applied to bioremediation of uranium-contaminated groundwater, as well as the creation of microbial fuel cells.

Metabolism
Currently known Shewanella species are heterotrophic facultative anaerobes. In the absence of oxygen, members of this genus possess capabilities allowing the use of a variety of other electron acceptors for respiration. These include thiosulfate, sulfite, or elemental sulfur, as well as fumarate. Marine species have demonstrated an ability to use arsenic as an electron acceptor as well. Some members of this species, most notably Shewanella oneidensis, have the ability to respire through a wide range of metal species, including manganese, chromium, uranium, and iron. Reduction of iron and manganese through Shewanella respiration has been shown to involve extracellular electron transfer through the employment of bacterial nanowires, extensions of the outer membrane.

Applications
The discovery of some of the respiratory capabilities possessed by members of this genus has opened the door to possible applications for these bacteria. The metal-reducing capabilities can potentially be applied to bioremediation of uranium-contaminated groundwater, with the reduced form of uranium produced being easier to remove from water than the more soluble uranium oxide. Scientists researching the creation of microbial fuel cells, designs that use bacteria to induce a current, have also made use of the metal reducing capabilities some species of Shewanella possess as a part of their metabolic repertoire.