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"Testing the Waters" -- The Discovery Files

The Discovery Files
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A toxin dangerous to humans may help E. coli fend off aquatic predators, enabling strains of E. coli that produce the toxin to survive longer in lake water than benign counterparts, a University of Buffalo study finds.

Credit: NSF/Karson Productions

Audio Transcript:

Straining to get it right

I'm Bob Karson with the discovery files--new advances in science and engineering from the National Science Foundation.

(Sound effect: outdoor sounds, lake) Ever go to the lake only to find the beach closed because of "high levels of e-coli?" Very frustrating, but be thankful these things are monitored. Now, researchers at the University at Buffalo and Mercyhurst University have found there's a strain of e-coli that may cause us to re-think the way we monitor recreational swimming areas.

It's a particularly insidious little bugger that produces a toxin harmful to humans. While most e-coli strains are harmless to us, these shiga toxin-encoding e-coli or STEC, intestinally speaking, can really rock your world and some symptoms can be serious enough to cause death.

The team took water samples that contained tiny, one-celled protists that feed on e-coli. They introduced regular e-coli, and the toxin-producing STEC. The STEC's toxin helped them fend off their aquatic predators and they suffered far fewer losses.

(Sound effect: lifeguard whistle closing beach) The researchers say if we base closure of a swimming area on just the overall population of e-coli, it could be misleading. If there's a small population with a high concentration of STEC, we may deem an unsafe beach, safe. If there's a large population of e-coli, but no STEC, we may close water that is safe. Current water-quality testing methods cannot be that specific, but this research points up that it may be time for a change. (Sound effect: water drop)

"The discovery files" covers projects funded by the government's National Science Foundation. Federally sponsored research--brought to you, by you! Learn more at or on our podcast.

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