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Chip Detects Harmful Bacteria in Food Products
Source
of Article: http://cr.pennnet.com/display_article/358081/15/ARTCL/none/TOPST/1/Chip-Detects-Harmful-Bacteria-in-Food-Products/
APRIL 2, 2009 – WEST LAFAYETTE, IN -- A tiny chip developed at Purdue University can detect harmful bacteria in food
products more accurately and significantly quicker than more traditional
tests.
Arun Bhunia, Purdue
professor of food science, has found a way to use human cell receptors in
biochips to detect the presence of Listeria monocytogenes, a bacterium
common in deli meats and some unpasteurized cheeses. Listeria
monocytogenes can cause sickness and death in people with weakened
immune systems. Bhunia's findings were reported this week in the early
online version of the journal Analytical Chemistry.
"If
you want to modify this, you could use different receptors to detect
salmonella, E.coli or any other pathogenic bacteria," Bhunia said.
"There are many potential uses."
Bacteria in a fluid are
passed over the biochip and attach to the cell receptors, changing the
conductivity of the solution. The chip senses the conductivity change and
signals to a computer that bacteria are present.
Researchers, including
Bhunia, had previously developed a chip that used antibodies instead of
cell receptors. The antibody chips also detected benign forms of bacteria,
however. Without being able to tell whether the bacteria were harmful, food
producers were forced to discard products that were suitable for
consumption.
"Companies could be
wasting resources because current testing methods don't show whether the
bacteria is pathogenic," said Ok Kyung Koo, a Purdue graduate student
working with Bhunia.
When bacteria come into
contact with the specific human cell receptor, the bacteria attach to that
cell, causing sickness. Benign versions of those bacteria do not bond with
receptors, making them better for bacteria detection in food products.
"Most of the tests
you have now may not be specific. There's a chance it could give you a
false positive," Bhunia said. "The test we have set up would only
detect pathogenic listeria."
Bhunia says current tests
for listeria and other pathogens take between one day and 10 to obtain
results. His biochips take less than 12 hours, and he believes that time
can be shaved to less than eight hours.
Since the chips are so
small — about the size of a postage stamp — they require only a small
sample. And Bhunia said that since the chips can be hooked up to a
computer, tests could be done on-site, eliminating the need to send samples
to outside labs.
The U.S. Department of
Agriculture funded Bhunia's research. The biochips worked with samples of
bacteria in a fluid that was passed over the chips. The next step is to
test the chips using samples taken from food products.
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