Biosensor
allows rapid testing of L. monocytogenes in food – study
Source
of Article: http://www.foodproductiondaily.com/Quality-Safety/Biosensor-allows-rapid-testing-of-L.-monocytogenes-in-food-study
By Jane Byrne, 23-Apr-2009
US and Indian scientists have
developed a new biosensor for use in a faster, more sensitive test for
detecting the deadliest strain of Listeria food poisoning
bacteria, according to an article in the current issue of Analytical
Chemistry.
The researchers note that numerous fast,
highly effective tests
already are available for five of the six known species of Listeria,
which use antibodies that signal the presence of the bacteria. However,
they claim that no rapid, sensitive tests are available for detecting Listeria
monocytogenes.
The foodborne pathogen L. monocytogenes causes
human listeriosis affecting pregnant women, newborns, the elderly and immunocompromised
individuals, with the microbe causes hundreds of deaths and thousands
of hospitalizations each year in the US.
Stubborn pathogen
According to the authors of the study,
Listeria can tolerate salt, pH changes, inadequate thermal
pasteurisation and refrigerated temperatures, with major sources of
listeriosis outbreaks being fully processed ready-to-eat
(RTE) foods, which can be contaminated by poor hygienic practices
during post-processing handling and packaging.
The scientists explained that their biosensor
uses heat shock proteins instead of the antibodies used in other tests,
and they said the results of their study showed that their sensor was
faster and more sensitive at detecting the bacterium than
antibody-based tests, with a microbe capture rate up to 83 per cent
higher than antibody-based tests.
The new biosensor will reduce the likelihood
of false-positive results for L monocytogenes in food and may
lead to improved tests for detecting other types of pathogens, added
the researchers.
Inhibition using film
Meanwhile, an extruded composite food
packaging film containing pectin, polylactic acids (PLAs) and nisin can
inhibit L monocytogenes, according to scientists based at the
Agricultural Research Service (ARS) of the US Department of
Agriculture.
The scientists said that they chose brain
heart infusion (BHI), orange juice and liquid egg white as the foods
for the study as they serve as representatives for neutral, high acid
and low acid foods respectively.
The film, found the researchers, was effective
in reducing L. monocytogenes by 2.1, 4.5 and 3.7 log units mL-1
in the BHI, as well as in the orange juice and liquid egg after 48
hours at 24°C.
The ARS scientists concluded that this
composite film has great potential to reduce post-process growth of
food pathogens, and they added that they will further explore the use
of nisin containing films as packaging materials with antimicrobial
activity against L.
monocytogenes for solid foods such as meat products.
Source: Analytical Chemistry
Title: Targeted Capture of Pathogenic Bacteria using a Mammalian
Cell Receptor coupled with Dielectrophoresis on a Biochip
Published online: DOI: 10.1021/ac9000833
Authors: Koo, OK; Liu, Y; Shuaib, S; Bhattacharya, S; Ladisch, M;
Bashir, R; Bhunia, A.
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