When you go to the dentist to have your jaws X-rayed, you’ll notice that you have to wear a heavy lead apron—and the person who takes the X-ray leaves the room to do it. X-rays are safe, but these precautions give you some sense of how careful we have to be around even relatively harmless levels of radiation. The problem is that unsafe levels of radiation can mess with the cells and molecules in our body, warping them and even breaking them apart. It does the same thing to microbial cells.
But there’s one bacterium called Deinococcus radiodurans that can live through blasts of radiation thousands of times greater than the level that would kill a human being. Radiation is measured in units called rads. A dose of 500 to 1,000 rads is enough to kill a person. D. radiodurans thrives even after being hit by up to 1,500,000 rads—yikes!
The bacterium’s Latin name means "strange berry that withstands radiation." Scientists who study D. radiodurans have nicknamed it "Conan the Bacterium." The Guinness Book of World Records dubbed it the world’s toughest bacterium.
So how does D. radiodurans manage to live through such intense blasts of radiation?
If you’ve read other pages on this site, you may have learned that some bacteria form protective spores to survive through drought, heat and radiation (see How Microbes Form Spores). So could it be that D. radiodurans forms extra tough spores?
Actually no, it’s not a spore-former. Anyway, while bacterial spores can endure radiation, none can take nearly as much as D. radiodurans can. So, without any special protective coating, what then does D. radiodurans do to withstand all that radiation?