[tt] Radiation resistant bacteria

[Isabelle Hakala]

http://chronicle.augusta.com/stories/latest/lat_126668.shtml

One of the world's tiniest celebrities hails from one of the planet's  
toughest neighborhoods.

Rainier Ehrhardt/Staff
Dr. Christopher Bagwell (right) and Charlie Milliken look at the  
radiation-resistant bacteria at Savannah River National Laboratory.  
The organism, found inside tanks at Savannah River Site, is able to  
rapidly rebuild its DNA.
Its story began a couple of years ago, when scientists fished a  
strange slime off a probe used to examine decades-old, high-level  
nuclear waste inside tanks stored at Savannah River Site.

"At first, nobody was sure what it was," said Christopher "Kitt"  
Bagwell, a senior scientist at the top-secret Savannah River National  
Laboratory.

Turns out, the greenish-orange slime was alive.

The more it was studied, the more it enamored scientists who were  
fascinated with its ability to survive radiation doses thousands of  
times greater than what is considered lethal to humans.

"Finding an organism in such a toxic environment is very unexpected,"  
said Dr. Bagwell, who will present a paper about the bacteria -  
dubbed kineococcus radiotolerans - to the American Society for  
Microbiology next month.

In addition to thriving in the face of normally-lethal radiation, the  
organism also demonstrates remarkable survival characteristics in  
terms of its DNA.

Humans and most organisms can tolerate few breaks in DNA molecules,  
he said, but kineococcus radiotolerans has the ability to reassemble  
itself.

"With this organism, we can take an intact DNA molecule, blast it  
into little pieces, and in five to six hours the organism is restored  
and growing normally again," Dr. Bagwell said.

Dr. Bagwell and others who have studied the organism hope further  
research will yield clues that could aid in medical research, cancer  
studies and other areas.

"There's a lot of excitement about this organism because of its  
ability to withstand tremendous abuse," he said. "What we don't know  
is how it does these things - and what more it can do. That's the  
direction we're going now."


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