Microorganisms - ENVIS Centre

Researchers at Ohio State University were able to show how the Shewanella oneidensis bacterium breaks down metal to chemically extract oxygen.

Researchers are studying some common soil bacteria that "inhale" toxic metals and "exhale" them in a non-toxic form. The bacteria might one day be used to clean up toxic chemicals left over from nuclear weapons production decades ago.

Atomic force microscopic image of Shewanella oneidensis bacterium expressing the protein OmcA on metallic mineral hematite. Oval marks indicate the location of the bacterium where OmcA (red colour) is seen surrounding the bacterium.

Courtesy: Brian Lower, Ohio State University, USA.

A study, published online on March 16, 2009 in the journal Applied and Environmental Microbiology, provides the first evidence that Shewanella maneuvers proteins within the bacterial cell into its outer membrane to contact metal directly. The proteins then bond with metal oxides and the bacteria utilize the oxygen of these oxides for respiration to make energy which is considered as an ancient form of respiration for bacteria living in deep waters and sediments where the oxygen availability is either low or nil. Further work is progress to know whether Shewanella produces OmcA on the cell surface when exposed to uranium and technetium also.

Shewanella oneidensis (MR-1) bacteria on iron oxide mineral hematite surface.

Courtesy : Pacific Northwest National Laboratory.

Source: www.sciencedaily.com