Featured Research

from universities, journals, and other organizations

UMass Amherst Researchers Develop Technique To Screen For Live Bacteria, Could Improve Food Safety

Date:
August 10, 2005
Source:
University Of Massachusetts Amherst
Summary:
In work that has implications for the food safety industry, scientists, and environmental and public health agencies, University of Massachusetts Amherst researchers have developed a molecular-based method that distinguishes live bacterial cells from dead ones.

AMHERST, Mass. − In work that has implications for the food safety industry, scientists, and environmental and public health agencies, University of Massachusetts Amherst researchers have developed a molecular-based method that distinguishes live bacterial cells from dead ones. The study was published online June 1 in the Journal of Microbiological Methods.

Developed by microbiologist Robert Levin, food science, and doctoral student Shishan Wang, the new method adds a level of specificity to DNA detection and could be applied to a suite of pathogens, perhaps preventing massive recalls of meat carrying E. coli, or enhancing tests that check for contaminants in drinking water.

“You aren’t only protecting the consumer” with such tests, says Levin, “you could save thousands of dollars.”

The research is supported by a Special Seafood Safety grant from the U. S. Department of Agriculture.

The new method takes advantage of a technique called polymerase chain reaction (PCR), which scientists use to make lots of copies of a small, specific stretch of DNA. PCR generates large quantities of DNA from tiny samples, and is used widely by scientists studying everything from birds to humans to bacteria.

Levin and Wang have used PCR to screen seafood for the DNA of Vibrio vulnificus, a disease-causing bacterium from the same family as those that cause cholera. But PCR just copies the designated DNA, it doesn’t indicate whether the DNA came from a cell that was dead or alive, critical information when testing food or water for organisms that make people sick.

The first step of PCR is heating the sample that contains the DNA of interest. At the right temperature, the two strands that make up a DNA molecule separate, and only then can they be copied. But Levin and Wang weren’t interested in copying all the V. vulnificus DNA in their sample, just the DNA from bacteria that were alive.

So the researchers treated their bacteria samples with ethidium bromide monoazide (EMA), a chemical that winds its way in between the strands and building blocks of a DNA molecule. EMA will insert itself into any DNA it finds, but it can’t get through the cell membranes of healthy, living bacteria. However, EMA can easily get to the DNA of a dead or dying bacterium with a damaged cell membrane.

After dosing the bacteria with EMA, the researchers zapped their samples with high-intensity visible light causing the EMA to form strong, cross-linking bonds with the DNA it’s tangled up in. These bonds prevent the DNA molecules from separating, so they can’t be copied during PCR. Only DNA from live cells will be copied, alerting the testers to the presence of living bacteria.

“Once you’ve determined the optimum concentrations of EMA you can completely inhibit amplification of DNA from dead cells,” says Levin.

The scientists have worked out the protocols for testing for V. vulnificus, and with minor adjustments the method could be applied to other disease-causing critters.

“This could take PCR one giant step forward,” says Levin.


Story Source:

The above story is based on materials provided by University Of Massachusetts Amherst. Note: Materials may be edited for content and length.


Cite This Page:

University Of Massachusetts Amherst. "UMass Amherst Researchers Develop Technique To Screen For Live Bacteria, Could Improve Food Safety." ScienceDaily. ScienceDaily, 10 August 2005. <www.sciencedaily.com/releases/2005/08/050810013957.htm>.
University Of Massachusetts Amherst. (2005, August 10). UMass Amherst Researchers Develop Technique To Screen For Live Bacteria, Could Improve Food Safety. ScienceDaily. Retrieved October 20, 2014 from www.sciencedaily.com/releases/2005/08/050810013957.htm
University Of Massachusetts Amherst. "UMass Amherst Researchers Develop Technique To Screen For Live Bacteria, Could Improve Food Safety." ScienceDaily. www.sciencedaily.com/releases/2005/08/050810013957.htm (accessed October 20, 2014).

Share This



More Health & Medicine News

Monday, October 20, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Microneedle Patch Promises Painless Pricks

Microneedle Patch Promises Painless Pricks

Reuters - Innovations Video Online (Oct. 18, 2014) Researchers at The National University of Singapore have invented a new microneedle patch that could offer a faster and less painful delivery of drugs such as insulin and painkillers. Video provided by Reuters
Powered by NewsLook.com
Raw: Nurse Nina Pham Arrives in Maryland

Raw: Nurse Nina Pham Arrives in Maryland

AP (Oct. 17, 2014) The first nurse to be diagnosed with Ebola at a Dallas hospital walked down the stairs of an executive jet into an ambulance at an airport in Frederick, Maryland, on Thursday. Pham will be treated at the National Institutes of Health. (Oct. 16) Video provided by AP
Powered by NewsLook.com
Raw: Cruise Ship Returns to US Over Ebola Fears

Raw: Cruise Ship Returns to US Over Ebola Fears

AP (Oct. 17, 2014) A Caribbean cruise ship carrying a Dallas health care worker who is being monitored for signs of the Ebola virus is heading back to Texas, US, after being refused permission to dock in Cozumel, Mexico. (Oct. 17) Video provided by AP
Powered by NewsLook.com
Spanish Govt: Four Suspected Ebola Cases in Spain Test Negative

Spanish Govt: Four Suspected Ebola Cases in Spain Test Negative

AFP (Oct. 17, 2014) All four suspected Ebola cases admitted to hospitals in Spain on Thursday have tested negative for the deadly virus in a first round of tests, the government said Friday. Duration: 00:55 Video provided by AFP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Health & Medicine

Mind & Brain

Living & Well

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins