Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Dangerous E. coli Strains May Linger Longer in Water

17.06.2013
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 new study finds.

Researchers from the University at Buffalo and Mercyhurst University reported these results online June 7 in the journal Applied and Environmental Microbiology.


Credit: University at Buffalo

The protist Tetrahymena hunts E. coli in this photo illustration, which features a microscope image of Tetrahymena (left). A new study finds that Shiga toxin may help E. coli survive in the face of such predation.

“The take-home lesson is that E. coli that produce Shiga toxin persisted longer in recreational water than E. coli that don’t produce this toxin,” said UB Professor of Biological Sciences Gerald Koudelka, PhD, who led the study. “This is because the toxin appears to help E. coli resist predation by bacterial grazers.”

The findings have implications for water quality testing. They suggest that measuring the overall population of E. coli in a river or lake — as many current tests do — may be a poor way to find out whether the water poses a danger to swimmers.

Past research has shown that overall E. coli concentrations don’t always correlate with the levels of dangerous, Shiga toxin-producing E. coli present in the water, Koudelka said. His new study provides one possible explanation for why this might be.

E. coli, short for Escherichia coli, is a bacteria found in human and animal intestines. Most types of E. coli are harmless. But those that produce Shiga toxin can make people very sick, causing symptoms such as hemorrhagic diarrhea. Severe cases can lead to death.

In their new study, Koudelka and his colleagues obtained water samples from Presque Isle State Park and Mill Creek Stream, both in northern Pennsylvania. The water contained protists — tiny, single-cellular creatures that feed on E. coli.

To test how Shiga toxin affects E. coli’s survival, the scientists placed several different strains of E. coli into the water samples: three strains of Shiga toxin-encoding E. coli (STEC), and three strains of E. coli that did not produce the toxin.

The results: The toxin producers fared much better against the grazing protists than their toxin-free counterparts. Over 24 hours, STEC populations fell by an average of 1.4-fold, in contrast to 2.5-fold for the Shiga-free bacteria.

The STEC strain that produced the most Shiga toxin also lasted the longest, persisting in water for about 48 hours before declining in numbers.

Each E. coli strain was tested in its own experiment (as opposed to one big experiment that included all six). All of the STEC strains studied were ones that had previously caused illness in humans.

The findings add to evidence suggesting that current water quality tests may not capture the whole story when it comes to E. coli danger in recreational waters, Koudelka said.

“If you’re only testing generally for fecal indicator bacteria, you could miss the danger because it’s possible to have low levels of E. coli overall, but have most of that E. coli be of the STEC variety,” he said. “This would be worse than having a large E. coli population but no STEC.”

The opposite problem can also occur, Koudelka said.

“You could have high E. coli populations in a lake, but absolutely no STEC,” he said. “This is the economic part of it: It’s a problem because you might have a beach that’s closed for days even though it’s safe.”

The study was funded by the National Science Foundation and Mercyhurst University, and the research is part of Koudelka’s ongoing investigations into the lives of aquatic microbes, including bacteria and protists. He is particularly interested in how one species may help regulate the level of others through predation and other interactions. Koudelka’s work has shown that Shiga and other dangerous toxins probably arose as antipredator defenses in what he calls a “microbiological arms race,” and not to kill humans.

Charlotte Hsu | Newswise
Further information:
http://www.buffalo.edu

More articles from Life Sciences:

nachricht Scientists spin artificial silk from whey protein
24.01.2017 | Deutsches Elektronen-Synchrotron DESY

nachricht Choreographing the microRNA-target dance
24.01.2017 | UT Southwestern Medical Center

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Scientists spin artificial silk from whey protein

X-ray study throws light on key process for production

A Swedish-German team of researchers has cleared up a key process for the artificial production of silk. With the help of the intense X-rays from DESY's...

Im Focus: Quantum optical sensor for the first time tested in space – with a laser system from Berlin

For the first time ever, a cloud of ultra-cold atoms has been successfully created in space on board of a sounding rocket. The MAIUS mission demonstrates that quantum optical sensors can be operated even in harsh environments like space – a prerequi-site for finding answers to the most challenging questions of fundamental physics and an important innovation driver for everyday applications.

According to Albert Einstein's Equivalence Principle, all bodies are accelerated at the same rate by the Earth's gravity, regardless of their properties. This...

Im Focus: Traffic jam in empty space

New success for Konstanz physicists in studying the quantum vacuum

An important step towards a completely new experimental access to quantum physics has been made at University of Konstanz. The team of scientists headed by...

Im Focus: How gut bacteria can make us ill

HZI researchers decipher infection mechanisms of Yersinia and immune responses of the host

Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...

Im Focus: Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.

While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Sustainable Water use in Agriculture in Eastern Europe and Central Asia

19.01.2017 | Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

 
Latest News

Breaking the optical bandwidth record of stable pulsed lasers

24.01.2017 | Physics and Astronomy

Choreographing the microRNA-target dance

24.01.2017 | Life Sciences

Spanish scientists create a 3-D bioprinter to print human skin

24.01.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>