Shewanella are facultatively anaerobic, Gram-negative bacteria, motile by polar flagella, rod-like, and generally associated with aquatic or marine environments. They are capable of using a variety of compounds as electron acceptors, including oxygen, iron, manganese, uranium, nitrate, nitrite, fumarate, to name but a few. This ability makes Shewanella important for bioremediation of contaminated metals and radioactive wastes. The genus Shewanella comprises 36 recognized and hundreds of uncharacterized cultivable species.

Shewanella halifaxensis (strain HAW-EB4) is an obligately respiratory denitrifying and RDX-mineralizing bacterium isolated from sediment in a munitions-dumping area of the Emerald Basin (depth of 215 m, Atlantic Ocean), offshore of Halifax Harbour (Nova Scotia, Canada). This psychrophilic, sodium cations-requiring and slightly halophilic bacterium is able to degrade hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) at 10 degrees Celsius. RDX is a member of a family of nitramine compounds which are used in the production of explosives. These chemicals are toxic and can be a major source of contamination of marine and freshwater sediments.