Study finds novel method to test food for
contamination
By Jane Byrne
26-Sep-2008 –
Source of Article: http://www.foodproductiondaily.com/Quality-Safety/Study-finds-novel-method-to-test-food-for-contamination
The
group said their approach, the details of which were published in the journal, Microbial
Biotechnology, is more directly related to toxicity
assessment than the conventional techniques to test food for bacterial
contamination and safety.
According
to the researchers, led by Janine Trempy of the
Detection
evasion
They
claim that recent cases of Salmonella
contaminated tomatoes, peanut butter and spinach as well as C.
botulinum contaminated canned meats indicate
the ease by which food-associated bacterial pathogens evade detection, often
resulting in massive recalls of popular food items.
According
to the researchers, existing tests only work to detect bacteria that have
already been characterized, based on a specific sequence of DNA or the type of
protein they produce,.
They
said that such tests cannot tell whether the contaminating bacteria are alive
or dead, they cannot directly assess their toxic potential and sometimes do not
detect newly emerging or genetically rearranged strains as bacteria mutate,
thus they argue there is a need for detection methods based on parameters
different from those describing bacterial presence.
Toxic
reaction
Trempy said that
bacteria sometimes only exhibit the behaviour that
can case illness under specific environmental conditions and it is that toxic
reaction the technology detects.
She said
the team’s novel approach is based on previous research looking at the colour changes in pigment-bearing cells from Siamese
fighting fish.
According
to Trempy, studies have 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.
She said
that the change in pigment location in response to a toxic chemical is rapid,
obvious and can be numerically described.
Results
“We
discovered that the pigment bearing cells, erythrophores,
respond immediately to certain food associated, toxin producing bacteria
responsible for making humans sick,” said Trempy. “There is the potential to directly assess the
toxic behaviour of the contaminating bacteria, not
just the simple presence of the DNA or protein of these bacteria.”
They
said that this method can detect such food-associated bacteria as Salmonella
and Clostridium perfringens, responsible for diarrhoeal illnesses; Bacillus cereus, responsible
for gastrointestinal illness and Clostridium botulinum,
which causes toxin-induced botulism.
Trempy said that
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
The
researchers said their method has been patented.
Trempy said that
further work is also required to develop a pigment bearing cell for mass
production and commercial use and that the team anticipate that portable kits
could result that would enable food processors, distributors and handlers, or
even consumers to quickly test food for contaminating bacterial toxicity.
Source: Microbial
Biotechnology
Published online ahead of print
Erythrophone cell response to food
associated pathogenic bacteria: implications for detection
J.R. Hutchison, S. R. Dukovcic, K. P. Dierksen, C. A. Carlyle, B. A. Caldwell, J
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