Washington: Scientists have observed that just a handful of geneti c mutations give E coli the capacity to withstand doses of radiation that would otherwise doom the microbe. Scientists coaxed the model bacterium Escherichia coli to dramatically resist ionising radiation. This in fact helped them to get a better understanding of how organisms can resist radiation damage to cells and repair damaged DNA.
"What our work shows is that the repair systems can adapt and those adaptations contribute a lot to radiation resistance," said Professor Michael Cox of the University of Wisconsin-Madison. In previous work, Cox and his group, working with John R Battista from Louisiana State University, showed that E coli could evolve to resist ionising radiation by exposing cultures of the bacterium to the highly radioactive isotope cobalt-60.
Explaining the process of experiments conducted by Cox, he said "We blasted the cultures until 99 per cent of thebacteria were dead. Then we'd grow up the survivors and blast them again. We did that twenty times."
“Deinococcus evolved mainly to survive desiccation, not radiation so when conditions are right, it can repair damage very quickly and start growing again,” added Cox. Understanding the molecular machinery that allows some organisms to survive what would otherwise be lethal doses of radiation is important. The reason for this is that the same bacterial machinery that repairs DNA and protects cells in microbes, exists in humans and other organisms.
Although turning the new findings into application is in the distant future, the results could ultimately contribute designer microbes capable of helping clean radioactive waste sites or making probiotics that could aid patients undergoing radiation therapy for some cancers. The new study demonstrates that organisms can actively repair genetic damage from ionising radiati
