URI researchers make detection of
food pathogens quick, easy
New devices detect salmonella, E. coli, other bacteria
KINGSTON, R.I. -- June 26, 2000 -- More than 75 million people per year
become ill from food poisoning in the United States, 325,000 are hospitalized,
and 5,000 of them die from pathogens like Salmonella and E. coli. But detection
of these pathogens is getting easier, thanks to several new biosensors developed
by researchers at the University of Rhode Island.
Ten years in development, the biosensors use fiber optic technology to
quickly and accurately detect and quantify bacteria levels in meats, poultry
and other foods.
"There are about 6,000 meat and poultry processing plants in the
U.S., and they all are required by law to test their products for food pathogens,"
said A. Garth Rand, professor emeritus of food science at URI and a South
Kingstown resident. "Most of these plants don't have their own
labs, so they've got to send their samples out to commercial labs. Instead
of waiting several days to get results, they can use our biosensor and have
results in an hour."
Rand teamed up with Stephen Letcher of Kingston, professor of
physics, and Christopher Brown of Saunderstown, professor of chemistry,
to establish the URI Fiber Optic & Biosensor Research Group to tackle
the difficult problem of developing a fast and sensitive food pathogen sensor.
This research group is part of the University's Sensors and Surface Technology
Partnership. The U.S. Department of Agriculture has funded the research
for the last eight years.
"We are one of a very small number of research groups working on
food safety biosensors," said Rand. "And our combination of disciplines
is unique. The only way to solve this kind of problem is with an interdisciplinary
approach."
Focusing first on detecting Salmonella, one of the most common food pathogens,
the group developed several sensors that use vibrating quartz crystals or
fiber optic probes along with Salmonella antibodies that bind the pathogen
cells to the sensor. The latest version also uses microscopic magnetic beads
called microspheres.
"The surface of the beads are covered with antibodies that collect
the pathogen and are then labeled with a fluorescent dye," explained
Rand. "Then the beads are magnetically focused in front of optical
fibers and a laser signal reports the pathogen concentration."
The binding of the pathogen cells to the antibodies takes about 60 minutes,
while the process of determining the pathogen concentration takes just 60-90
seconds.
Although the sensor needs further refinement before it is complete, the
researchers are working with Pierson Scientific Associates of Andover, Mass.,
to develop portable prototypes of the device. The partnership was awarded
a Small Business Technology Transfer grant from the National Science Foundation
in 1998.
"While we've been primarily studying Salmonella, the system works
for most other food pathogens, too," Rand said. "In fact, we
believe it works even better for E. coli."
The URI researchers have also been working on biosensors for the U.S.
Army Natick Labs, which prepares Defense Department meals that are often
stored for years in remote locations. The Army has funded Rand's research
into developing sensors to detect pathogens in Army rations.
"They are especially concerned with detecting pathogens that grow
in low-moisture dried foods," explained Rand. "They needed a
quick way to see if pathogens are growing in the food they have stored around
the world."
For this project, Rand's team developed a membrane biosensor. When the
membrane is coated with antibodies and enzymes, the bacteria gets caught
on the membrane while the rest of the solution being tested passes through
it.
Next up for the URI researchers is the creation of a hand-held surface
scanning system similar to a supermarket checkout scanner that
uses video to detect the pathogens, and another that detects pathogens in
seafoods.
"These sensors will significantly enhance the safety of the food
supply and protect human health," concluded Rand.
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For Information: A. Garth Rand 874-4081,
Todd McLeish 874-7892
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