Death is the ultimate fate for most bacteria blasted by huge doses of radiation or parched by a severe lack of water. The genetic material irreversibly splinters into hundreds of pieces, dooming the organisms as surely as Humpty Dumpty.

But a few bacteria can "resurrect" themselves by quickly piecing their DNA back together—a strange ability that has mystified biologists for decades.

Now researchers have figured out how one species of these phoenix-like bacteria can rise from the ashes.

[...]

The organism can withstand massive doses of radiation and can even survive being completely dried out.

When that occurs, "there is no metabolism," Radman said. "The genome is shattered into hundreds of pieces. It is a dead cell.

"But out of this horrendous damage, it can resurrect."

[...]

But shredding these instructions renders them useless. Once DNA is split into multiple pieces, there's usually no way a cell's internal machinery can figure out how to piece everything back together again.

Reconstruction must be precise, because a message restitched in the wrong order is gibberish, dooming the organism.

[...]

Unlike most bacteria, however, D. radiodurans contains multiple copies of its genetic material, which can act as backups for each other, Radman says.

Imagine that a cell's DNA holds the message "Humpty Dumpty sat on a wall, Humpty Dumpty had a great fall."

Since the spots where DNA breaks because of radiation or damage are random, each copy of the genetic material will likely have breaks in unique locations.

So if one DNA strand breaks into the split messages "Humpty Dumpty sat on a wall" and "Humpty Dumpty had a great fall," there's likely another chunk of material floating around that can bridge the gap.

The material might read "sat on a wall, Humpty Dumpty," for example.

The bacteria then chemically glue matching pieces together. Once they're bound, the cells fill in the missing parts of each of the two stuck-together copies, the study shows...