Advance
offers revolution in food safety testing
Science Centric | 27 October 2008 12:02 GMT
— Source of Article: http://www.sciencecentric.com/news/article.php?q=08102724 Microbiologists at The new approach - made possible by fundamental
research on the colour 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 behaviour that can cause illness under
specific environmental conditions, and it's that toxic behaviour
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 characterised, 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 behaviour 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 diarrhoeal illnesses; Bacillus
cereus, responsible for gastrointestinal illness characterised
by vomiting and diarrhoea, and often referred to as
stomach flu, and Clostridium botulinum, which
causes toxin-induced botulism, characterised 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 immortalise 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 specialised 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. Source: Oregon
State University |
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