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Study: E. Coli Bacteria Can Build Resistance Quickly, Even To Ionizing Radiation

Totally on their own, E. coli bacteria have shown that they can evolve to a point where they are resistant to antibiotic drugs. Now some of the nation’s top scientists are showing how E. coli bacteria can resist ionizing radiation. They are taking advantage of the bacteria’s built-in ability to evolve when they encounter hostilities in the environment.

“Evolution of extreme resistance to ionizing radiation via genetic adaptation of DNA repair” is the name of the study by a 12-member research team from the University of Wisconsin-Madison, the Lawrence Berkeley National Laboratory, Louisiana State University and A&M College. The findings of the study are published in the online journal eLife.

According to the University of Wisconsin, the scientists involved in the study “coaxed the model bacterium Escherichia coli to dramatically resist ionizing radiation and, in the process, reveal the genetic mechanisms that make the feat possible.”

The study found that E. coli could withstand doses radiation that would otherwise doom a microbe after only a handful of genetic mutations. Authors of the study said their findings provide 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, “ says Michael Cox, senior author of the report.

Earlier work by Cox, a biochemistry professor at the University of Wisconsin-Madison, and John R. Battista, Louisiana State University professor of biological science, found that E. coli could evolve to resist ionizing radiation after being exposed to highly radioactive isotope cobalt-60.

“We blasted the cultures until 99 percent of the bacteria were dead, “ Cox said. “Then we’d grow up the survivors and blast them again.” When it was over, the E. coli could resist ionizing radiation at four orders of magnitude.

By way of comparison, they make E. coli similar to Deinococcus radiodurans, a bacterium found in the desert and shown in the 1950s to be “remarkably resistant to radiation.” That bacterium can survive 1,000 times the radiation that would kill a human.

“Deinococcus evolved mainly to survive desiccation, not radiation, “ Cox said. He said Deinococcus can repair itself and start growing again very quickly.

The study means it might be possible in the future to use designer microbes to help clean radioactive waste sites or to use probiotics to help patients undergoing radiation therapy.

© Food Safety News
  • John Munsell

    Perhaps the report’s authors can answer a related food safety question? Radiation treatment which ostensibly kills all pathogens is currently available in limited domestic locations. Are the authors stating that E.coli bacteria are evolving to the point where they survive the radiation treatment? Or, are they saying that such resistence might slowly occur in the future? When my miniscule plant experienced a recall of 270# of ground beef for potential E.coli contamination back in 2002, one corrective action USDA recommended to me was irradiation. Because of my size, cost to construct irradiation facilities, remoteness and freight considerations, this agency suggestion was totally non-viable, and the agency knew it. Nevertheless, USDA continues to suggest irradiation as an alternative, but this report seems to reveal that irradiation has seen its day in the sun. I’m concerned that our industry might be losing a valuable intervention. John Munsell

    • pawpaw

      John,
      Good questions. Since no reply on these yet, I’ll take a stab. E. coli living in our cattle receive little to no irradiation or similar stresses that would select for these extreme survival traits. Unless the slaughterhouse irradiated bacteria find their way back into herds, the tiny amounts of E. coli that are resistant, they ‘should’ be at a dead end. They will still be killed by recommended cooking methods, before beef consumption. Again, unless the irradiated bacteria are fed to our cattle, or remain in the processing plants to reinfect beef after each round of irradiation, I don’t see a way for E. coli becoming rad-resistant.

      Having said that, I think of Roundup/glyphosphate resistant weeds. Certain plant scientists thought they understood the mechanisms of glyphosphate resistance, and therefore thought it extremely unlikely that (so many) weeds would develop strong resistance, so quickly. But here we have it.

  • Cristo Des

    Titanium dioxide will exterminate E. colli and friends

    • J T

      Cristo, I prefer my burgers sans titanium dioxide…

  • BB

    Mother Nature always gets the last word.

  • farmber

    Hmmm… using photocatalytic biocidal paints to kill toxic bacteria in meat processing plants…
    – lets be sure to paint the executive corporate offices too as proof that there’s no concerns with harm to workers as non-targeted species…

  • pawpaw

    Agreed that heat in cooking kills E. coli. But E. coli can still populate the sink, sponges(s), cutting boards, etc. So I’d rather not have STEC E. coli in my kitchen.
    I don’t know about Canadian cows, but mine are all grass-fed and they still poop. Including E. coli as part of their normal intestinal flora.
    Re: a LOT more money: Our ground beef prices, and the local farmers market, are just above the average ground beef price nationwide. Roast prices also slightly above store prices of comparable cuts (excluding sales). So in my area (SE US) consumers can find locally raised beef, same or not much more money. Even less when several go together and split 1/2 or 1/4 of a beef. And you can meet the farmer who grew the animal, can give you its life history if you so desire, can custom order certain cuts, oft visit the family-run farm or slaughterhouse. Is it too much to ask that these local beef producers earn a little more/cover their costs for this level of transparency?