PNNL'S ROLE IN SCIENCE DISCOVERY ON HOW MICROBE SURVIVES OTHERWISE DEADLY RADIATION
19 August 2006 - DOE/Pacific Northwest National Laboratory

The study suggests why the bacterium Deinococcus radiodurans is able to survive radiation that would kill most other life instantly: It contains a high level of the metal manganese where you would find iron in other organisms, including human beings.

The measurements of the cellular concentrations of manganese and iron were performed at PNNL in Richland, Wash.

The following information is provided by Science Express and lead author Michael J. Daly of Uniformed Services University of Health Sciences in Bethesda, Md.

Radiation-Resistant Bug’s Survival Tool
The reason that the bacterium Deinococcus radiodurans can withstand extremes of ionizing radiation and dehydration appears to be tied to the relatively high levels of manganese and low levels of iron ions in its cells. In the past, researchers have suggested that this microorganisms extraordinary hardiness might have to do with the fact that each cell has 4-8 genome copies or that its chromosome has an unusual ring-like structure. Michael J. Daly and colleagues now show that the chromosome organization is unlikely to play a role in radiation resistance and that a high concentration of manganese ions relative to iron ions is essential to its ability to survive gamma-radiation. The authors suggest that the manganese may not provide protection from the initial radiation; rather, it protects cells against harmful reactive oxygen species that accumulate during the recovery from radiation.

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