Bacteria Genomes - SHEWANELLA ONEIDENSIS

Shewanella oneidensis is an important model organism for bioremediation studies because of its diverse respiratory capabilities.

S.oneidensis is a non-pathogenic Gram-negative microbe which can grow both aerobically and anaerobically utilising a diversity of electron acceptors (nitrite, nitrate, thiosulfate, iron, manganese, uranium) and presents a unique opportunity to investigate how environmental conditions alter the biology and ecology of a microorganism.

S.oneidensis has the ability to use more than ten different elements to generate energy and in the process modifies both the chemical form and subsequent environmental behavior. Shewanella renders uranium immobile in sediments and could prevent leaching into nearby rivers and precipitate out of groundwater so that they can be isolated, the organism also breaks down chromium, which the World Health Organisation lists as a cancer-causing agent.

The chemical reaction that reduces metals is relatively straightforward, but the details of how the organism makes this happen are a mystery, further research is necessary as to how the bacterium switches from consuming oxygen to consuming metals once the oxygen in its environment is depleted.

References:

Nat. Biotechnol. 22: 1118 - 1123, (2002)
http://shewanella.org/home.sjsp
http://genomenewsnetwork.org/articles/10_02/shewanella.shtml
http://www.er.doe.gov/production/ober/nov0602.html