Conan the Bacterium

The image above is not of a four-leaf clover.  It’s of a quartet of bacteria named deinococcus radiodurans, colloquially referred to (in the singular) as “Conan the Bacterium.”  Why?  Because much like its namesake Conan the Barbarian, our bacterium friend is incredibly tough, surviving things that many thought were necessarily fatal.

In 1956, researchers in Oregon were testing a theory.  They believed that we could keep canned meat from spoiling by irradiating it, killing off contaminants.  By destroying any bacteria in the can, the ground meat inside would never spoil, or so the theory went.  But the experiment failed.  The meat spoiled, and the research team concluded that something had to have survived the radiation.   They were right: unlike everything else in the can, Conan the Bacterium survived.  Biologically, it has a design aspect which makes this possible.  As NASA notes, Conan’s “genetic code repeats itself many times so that damage in one area can be recognized and quickly repaired.”

Indeed, when it comes to surviving radiation exposure, Conan is second to none.  For context, 5 Gy (pronounced “gray” – the unit used for measuring doses of ionized radiation) is enough to kill an average person.  The bacterium E. coli cannot survive exposures over 800 Gy and sometimes dies off at levels as low as 200 Gy.  But Conan is special.  It comes out virtually unscathed at 5,000 Gy.  It is still viable 37% of the time at exposures of 15,000 Gy — 3,000 times more than what we mere humans can withstand. The Guinness World Record, in 1998, awarded Conan the title of “most radiation resistance life form.”

More than just a scientific curiosity, there are many practical uses for Conan.  It has been used for bioremediation of toxic waste sites already, and researchers are looking to see if it can be used for both DNA repair.  But most incredibly, Conan can be used as a living time capsule able to store and preserve data, even in the case of a massive disaster that wipes out most of our infrastructure.  In 2003, New Scientist reported of a test in which scientists took the words of It’s a Small World, encoded it in Conan’s DNA, and discovered that 100 bacterial generations later, the message survived.

Not bad for bacteria.

Bonus fact: The most radiation-resistant known animal is the tardigrade (pictured at link), a microscopic, water-dwelling, eight-legged organism, colloquially called a “water bear” because it appears to walk in a fashion similar to that of a bear.  It can survive radiation exposures equal to 4,000 Gy.  Even more impressive: in 2007, a cadre of tardigrades were taken into low Earth orbit and, for ten days, exposed to the vacuum of space. Many survived the trip — and some even laid viable, normal eggs afterward.

From the Archives: Tooth Be Told: The story of the bacteria in your toothbrush.

Related: A plush tardigrade.  Not microscopic, thankfully.