Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Dangerous strains of E. coli may linger longer in water than benign counterparts, study finds

14.06.2013
The research may help explain why water quality tests don’t always accurately capture health risks for swimmers

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.


The protist Tetrahymena hunts E. coli in this photo illustration, which features a microscope image of Tetrahymena (left).

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

“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.

Media Contact Information
Charlotte Hsu
Media Relations Manager, Architecture, Economic Development, Sciences, Urban and Regional Planning
Tel: 716-645-4655
chsu22@buffalo.edu

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

More articles from Studies and Analyses:

nachricht Win-win strategies for climate and food security
02.10.2017 | International Institute for Applied Systems Analysis (IIASA)

nachricht The personality factor: How to foster the sharing of research data
06.09.2017 | ZBW – Leibniz-Informationszentrum Wirtschaft

All articles from Studies and Analyses >>>

The most recent press releases about innovation >>>

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

Im Focus: Neutron star merger directly observed for the first time

University of Maryland researchers contribute to historic detection of gravitational waves and light created by event

On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...

Im Focus: Breaking: the first light from two neutron stars merging

Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.

Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....

Im Focus: Smart sensors for efficient processes

Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).

When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...

Im Focus: Cold molecules on collision course

Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.

How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...

Im Focus: Shrinking the proton again!

Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.

It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ASEAN Member States discuss the future role of renewable energy

17.10.2017 | Event News

World Health Summit 2017: International experts set the course for the future of Global Health

10.10.2017 | Event News

Climate Engineering Conference 2017 Opens in Berlin

10.10.2017 | Event News

 
Latest News

Electrode materials from the microwave oven

19.10.2017 | Materials Sciences

New material for digital memories of the future

19.10.2017 | Materials Sciences

Physics boosts artificial intelligence methods

19.10.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>