A2O-UncMter Farming, Saturday, October 16, 1999
(Continued from Pago A 1)
perform laboratory tests, but
they are costly and slow - some
times not even yielding results
for 48 to 72 hours, '(hat delay
requires that food products
remain stored in warehouses for
longer periods.
The biosensor will help in
overall quality control in food
processing plants, said collabo
rator Dr. Paul Edmonds, a pro
fessor of biology at Georgia Tech.
It would minimize the chance of
the final product being contami
nated.
Georgia Tech researchers - in
collaboration with Dr. Robert
Brackett, a professor at the
University of Georgia’s Center
for Food Safety and Quality
Enhancement in Griffin - have
been developing and testing the
biosensor in their laboratories
for about four years. Now they
are ready for a field test expect
ed to start in November at Gold
Kist in Carrollton, Ga., just west
of Atlanta.
Laboratory tests have proven
the biosensor is extremely sensi
tive, meaning it can detect
pathogens at minute levels of
500 cells per milliliter.
Researchers believe they can
improve that sensitivity to 100
cells per milliliter. Current labo
ratory methods only achieve
sensitivity levels of 5,000 cells
per milliliter, and they usually
take from eight to 24 hours to
yield results.
In addition, lab equipment
costs $12,000 to $20,000 per
instrument compared to an esti
mated $l,OOO to $5,000 for a
biosensor.
But before the biosensor
gains market acceptance, it
must prove its effectiveness in
the upcoming field test. The first
phase will last three to six
months, and researchers will be
comparing their biosensor test
results with the company's lab
findings.
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Food Safety Biosensor Detects Pathogens In Foods
One of the things we will be
looking at is reproducibility of
results, Hartman said. We will
split a sample for testing with
both of the technologies (the
biosensor and lab tests). For
every 1,000 tests we do, we will
look for the variation between
results of the two methods.
The biosensor can simultane
ously detect 12 different
pathogens, but researchers are
concentrating on six bacterial
species for now. They are
Salmonella, E. coli 0157:H7,
generic E. coli, Listeria monocy
togenes, Campylobacter jejuni
and Yersenia enterocolitica
(found primarily in red meat).
All of these pathogens are asso
ciated with stomach illness in
humans. When detected, they
are usually found in meat, but
sometimes they occur in pro
duce.
The biosensor operates with
three primary components -
integrated optics, immunoassay
techniques and surface chem
istry tests. It indirectly detects
pathogens by combining
immunoassays with a chemical
sensing scheme. In the
immunoassay, a series of anti
bodies selectively recognize tar
get bacteria. The “capture” anti
body is bound to the biosensor
and captures the target bacteria
as it passes nearby. A set of
“reporter” antibodies, which
bind with the same target
pathogen, contain the enzyme
urease, which breaks down urea
that is then added and produces
ammonia. The chemical sensor
detects the ammonia, affecting
the optical properties of the sen
sor and signaling changes in
transmitted laser light. These
changes reveal both the pres
ence and concentration of specif
ic pathogens in a sample at
extremely minute levels.
If pathogens are found with
the biosensor, then food proces
sors can make decisions more
Galvanized Li
quickly about applying treat
ments, such as antiseptics,
Edmonds said. Or they might
divert those products to cooking
operations, which would kill the
pathogens. And companies could
modify their sanitation plans.
The field test is expected to
demonstrate the biosensor’s
ability to improve food proces
sors’ operations, but it has some
competition from other tech
niques. One that is under devel
opment is an electrochemical
scheme that can reportedly
detect pathogens at 100 to 1,000
cells per milliliter.
Another technique already in
use is a DNA-based method
called PCR. While extremely
sensitive, it is very time-inten
sive in terms of sample prepara
tion.
Meanwhile, the integrated
optic interferometric sensor
technology upon which the
biosensor is based has already
been patented by Hartman and
the Georgia Tech Research
Corporation. It is also the basis
for a chemical contaminant
sensing system called E
SMART. That system is also
undergoing field tests. The
chemical sensor was licensed
commercially by the Atlanta
based company Photonic Sensor.
Commercialization for the
biosensor is still some time
away, researchers said. After the
field test at Gold Kist is com
pleted, researchers plan to
return to their laboratories to
further refine the technology.
“We would like to extend the
biosensor’s capabilities to detect
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Researcher Dr. Paul Edmonds, right, performs a
biosensor test at a Georgia poultry plant.
other pathogens, and we will
need to optimize the chemistry
for that,” Hartman said. “Also,
we would like to use the biosen
sor to address other food safety
issues, such as those associated
with insecticides, pesticides and
growth hormones.”
In addition to its application
in the poultry and beef indus
tries, Edmonds believes there is
a need for the biosensor in the
seafood industry. It contends
New Members Welcome In 4-
LANCASTER (Lancaster Co.)
Interested Lancaster County
youth are welcome to attend the
next meeting of the Red Rose
4-H Beef Club at 7:30 p.m.,
Wednesday, Oct. 13, at the
Lancaster Farm and Home
Center.
This special meeting for new
members will include official
sign-up, explanation of project
i
with a variety of waterborne
pathogens, particularly in shell
fish. And the dairy industry
could benefit from biosensor use,
as well, he said. An outbreak of
Listeria was found in Brie
cheese several years ago.
While biosensor development
continues, the state-funded
Agricultural Technology Research
Program at Georgia Tech is
sponsoring the project.
goals, introduction of leaders,
and a program on “Beef Breed
Identification.”
The club holds seven meet
ings each year, a round-up in
August, and a recognition ban
quet. Members of the club will
have the opportunity to partici
pate in livestock and meats
judging programs, community'
fair beef shows, and the
Pennsylvania Farm Show.
For additional information,®
contact Chet Hughes, Penn
State Cooperative Extension
livestock agent, at (717) 394-
6851.
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