Advance
offers revolution in food safety testing
Public release date:
25-Sep-2008
Source of Article: http://www.eurekalert.org/pub_releases/2008-09/osu-aor092508.php
CORVALLIS, Ore. -- Microbiologists at Oregon State University have developed
a new technology to detect illness-causing bacteria – an advance that could
revolutionize the food industry, improving the actual protection to consumers
while avoiding the costly waste and massive recalls of products that are
suspected of bacterial contamination but are perfectly safe.
The new approach - made possible by fundamental research on the color
changes in pigment-bearing cells from Siamese fighting fish - should be easier
to use, faster and more directly related to toxicity assessment than
conventional approaches now used to test food for bacterial contamination and
safety.
The technology has been patented, and the findings were just published in Microbial
Biotechnology, a professional journal. Further studies will be needed
before the system is ready for commercial use.
"Rapid methods are not readily available to directly assess the
toxicity of bacterial contamination in a user-friendly fashion," said
Janine Trempy, professor of microbiology and
associate dean of the OSU College of Science. "When this new technology is
commercially available, we should be able to provide a higher level of
assurance to the consumer while avoiding the waste of millions of dollars worth
of food that is suspected of bacterial contamination, but actually is
safe."
Bacterial illnesses associated with food and water can produce symptoms
ranging from mild stomach upset to severe illnesses and even death, and they
are common. It's been estimated there are about 76 million illnesses of this
type every year that cost the
Part of the problem is that conventional food safety testing done with
DNA-based tests or antibody-based methods only indicate the presence of
specific bacteria, which does not necessarily describe toxicity and the
potential to cause harm. Sometimes bacteria only exhibit the behavior that can
cause illness under specific environmental conditions, and it's that toxic
behavior that we need to detect, Trempy said.
"Bacteria are common on exposed surfaces, including the food products
we consume," Trempy said. "Simply knowing
they are there doesn't completely tell you, in a direct measurement, about
their potential to make you sick or whether the food is safe to eat."
Existing tests only work to detect bacteria that have already been
characterized, based on a specific sequence of DNA or type of protein they
produce. Such tests can't tell whether the contaminating bacteria are alive or
dead, they can't directly assess their toxic potential and sometimes don't
detect newly emerging or genetically rearranged strains as bacteria mutate.
The new approach, by contrast, is built on the unusual characteristics of
certain "chromatophore" or pigment bearing
cells, called erythrophores, from Siamese fighting
fish, whose response to specific toxic chemicals have been studied in detail by
Trempy's collaborator, OSU biochemist Phil McFadden.
This research found that when Siamese fighting fish encounter certain
stressful or threatening environmental conditions, such as exposure to toxic
chemicals like mercury, the erythrophores change
appearance, and the pigment moves in a characteristic pattern to an internal
part of the cell. The change in pigment location in response to a toxic
chemical is rapid, obvious and can be numerically described.
Another kind of stressful or threatening situation which also causes the
location of pigment to change is the toxic threat posed by illness-causing
bacteria. Some of these bacteria are associated with food.
"We discovered that the pigment bearing cells, erythrophores,
respond immediately to certain food associated, toxin producing bacteria
responsible for making humans sick," Trempy
said. "There is potential to directly assess the toxic behavior of the
contaminating bacteria, not just the simple presence of the DNA or protein of
these bacteria. And this response can be easily seen under a low-power
microscope and quickly quantified, numerically, to describe the intensity of
the situation."
This technology can detect such important food-associated bacteria as
Salmonella and Clostridium perfringens, responsible
for diarrheal illnesses; Bacillus cereus, responsible for gastrointestinal
illness characterized by vomiting and diarrhea, and often referred to as
stomach flu, and Clostridium botulinum, which causes
toxin-induced botulism, characterized by paralysis.
Further studies are needed to define the pigment bearing cell response to
other important bacteria of concern, such as E. coli O157:H7 and Listeria, Trempy said. Research is also needed to immortalize a
pigment bearing cell line for mass production and commercial use. These
advances should be possible and progress is being made on both issues in continuing
research, she said.
It's possible, Trempy said, that portable kits
could be developed that would not require specialized training to use. Results
would be available in minutes, convenient and would allow food processors,
distributors, handlers, or even consumers to quickly assess food for
contaminating bacterial toxicity.
Several OSU graduate and undergraduate students assisted on this research
and the recent peer reviewed publication. The Department of Homeland Security,
Howard Hughes Medical Institute, the Dr. Harry B. and Ralph H. Levey Philanthropic Fund, and the Tartar Foundation
supported the student research fellowships.
###
Editor's Note: Digital photographs are available of Siamese fighting fish;
as well as the changes that take place in erythrophore
cells five minutes after exposure to food-associated pathogenic bacteria; at
these URLs:
Fish: http://oregonstate.edu/dept/ncs/photos/Betta%20splendens3A.JPG
http://oregonstate.edu/dept/ncs/photos/Betta%20splendens3.JPG
Cells: http://oregonstate.edu/dept/ncs/photos/Cell%20example%20Trempy.jpg
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