An exoelectrogen normally refers to a bacterium or prokaryote

Prokaryote

The prokaryotes are a group of organisms that lack a cell nucleus , or any other membrane-bound organelles. The organisms that have a cell nucleus are called eukaryotes. Most prokaryotes are unicellular, but a few such as myxobacteria have multicellular stages in their life cycles...

 that has the ability to transfer electrons extracellular

Extracellular

In cell biology, molecular biology and related fields, the word extracellular means "outside the cell". This space is usually taken to be outside the plasma membranes, and occupied by fluid...

ly. This normally occurs via an external electron acceptor such as strong oxidizing agent

Oxidizing agent

An oxidizing agent can be defined as a substance that removes electrons from another reactant in a redox chemical reaction...

 in aqueous solution

Aqueous solution

An aqueous solution is a solution in which the solvent is water. It is usually shown in chemical equations by appending aq to the relevant formula, such as NaCl. The word aqueous means pertaining to, related to, similar to, or dissolved in water...

 or a solid conductor/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....

.

The electrons are thought to be transferred along pili

Pilus

right|thumb|350px|Schematic drawing of bacterial conjugation. 1- Donor cell produces pilus. 2- Pilus attaches to recipient cell, brings the two cells together. 3- The mobile plasmid is nicked and a single strand of DNA is then transferred to the recipient cell...

 (external cell structures used in conjugation

Bacterial conjugation

Bacterial conjugation is the transfer of genetic material between bacterial cells by direct cell-to-cell contact or by a bridge-like connection between two cells...

 and adhesion

Adhesion

Adhesion is any attraction process between dissimilar molecular species that can potentially bring them in close contact. By contrast, cohesion takes place between similar molecules....

).

Cells are able to do this strictly in the absence of oxygen as during aerobic respiration a cell converts an energy source into ATP

Adenosine triphosphate

Adenosine-5'-triphosphate is a multifunctional nucleoside triphosphate used in cells as a coenzyme. It is often called the "molecular unit of currency" of intracellular energy transfer. ATP transports chemical energy within cells for metabolism...

, carbon dioxide and water via glycolysis

Glycolysis

Glycolysis is the metabolic pathway that converts glucose C6H12O6, into pyruvate, CH3COCOO− + H+...

, the Krebs cycle and oxidative phosphorylation

Oxidative phosphorylation

Oxidative phosphorylation is a metabolic pathway that uses energy released by the oxidation of nutrients to produce adenosine triphosphate . Although the many forms of life on earth use a range of different nutrients, almost all aerobic organisms carry out oxidative phosphorylation to produce ATP,...

whereas in the absence of oxygen, water is not created and in its place electrons and hydrogen ions are formed.