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The Shewanella genus is characterized as facultatively anaerobic, Gram-negative, motile by polar flagella, rod-like microorganisms. It is found in a variety of environments such as freshwater lakes, marine sediments, subsurface formations, and at variable depths in redox stratified aquatic systems. They have an extraordinary ability of respiring a diverse group of compounds as electron acceptors, such as oxygen, iron, manganese, uranium, chromium, vanadium, nitrate, nitrite, and fumarate. This respiratory versatility makes Shewanella especially important for bioremediation of metal contaminated- and radioactive waste- sites. The genus Shewanella presently comprises more than 20 recognized species. Strain W3-18-1 was isolated from Pacific Ocean marine sediments underlying 670 m of water (Murray et al ., 2001), off the coast of Washington State. Strain W3-18-1 was isolated along with other Shewanella strains using a standard anaerobic enrichment technique with flasks incubated at 8 o C (Stapleton et al ., 2005). Shewanella sp. W3-18-1 is a psychrophile that can reduce metals and form magnetite at 0 o C. This is of particular interest for bioremediation of cold environments and for the understanding of metal biogeochemical cycles in deep marine environments while it has not been fully analyzed as to species, sequence analyses suggests its S. putrefaciens -like. References: Stapleton Jr, R.D., Z.L. Sabree, A.V. Palumbo, C.L. Moyer, A.H. Devol, and J. Zhou. 2005. Metal reduction at cold temperatures by Shewanella isolates from various marine environments. Aquat. Microb. Ecol. 38:81-91. Murray, A.E., D. Lies, G. Li, K. Nealson, J. Zhou, and J.M. Tiedje. 2001. DNA/DNA hybridization to microarrays reveals gene-specific differences between closely related microbial genomes. Proc. Natl. Acad. Sci. USA. 98:9853-9859.
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