Bacteria that can eat up nuclear waste protect their DNA from radiation damage by packing the genes into a tight ring, researchers have found.

Deinococcus radiodurans is not only the world's most radiation-resistant organism, but it can also survive extreme cold and dryness. For decades, researchers have been trying to figure out how the bacterium resists radiation. Most organisms have enzymes to repair DNA, but Deinococcus' enzymes didn't show anything special.

Now Israeli chemists think the key could be its dense ring of tightly packed DNA.

Bacterial DNA ring is stained blue Courtesy: Avi Minsky

Radiation causes pieces of DNA to break off. The researchers suspect Deinococcus' tight ring keeps the bacterial DNA fragments in place and in order until they come back together.

Prof. Avi Minsky of the Weizmann Institute of Science's Organic Chemistry Department and his colleagues also found the bacteria have four copies of DNA.

The backups allow one copy to do its job of moving around to produce proteins while the three others remain packed in the protective ring.

Unfortunately, human DNA is structured very differently so we won't benefit directly from the finding, Minksy said.

As for how the bacteria developed an appetite for radiation, no one knows. A team of Russian scientists believes Deinococcus originated on Mars, where radiation levels are higher.

Others, including Minksy, believe the bacteria evolved the resistance to cope with harsh, dry environments on Earth.

The study appears in Friday's issue of the journal Science.