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Vol. 18, No. 25 |
March 25, 1999 |
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Vol. 18, No. 25 |
March 25, 1999 |
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By harnessing glowing bacteria, scientists at the DuPont Co. and UD have created inexpensive biosensors that rapidly detect a key toxin in poultry feed, as well as broad classes of other environmental contaminants, including herbicides and metals.
"Our glowing bacteria should make it easier to pre-screen for potential contaminants, including aflatoxin B1, a known carcinogen that can be toxic for chickens," DuPont Co. researcher Tina K. Van Dyk reported March 21 during the American Chemical Society meeting in Anaheim, Calif.
Aflatoxin B1 is produced by molds found in poultry feed, and it "can be of concern for human foods, too," said Van Dyk, who recently earned her Ph.D. at UD, while working with Robin W. Morgan, animal and food sciences.
The research is fundamental, Van Dyk said, but it should be compatible with a simple, hand-held device for spotting contaminants on farms or in other real-world settings. "A light detector could be used to measure the bioluminescent response of these genetically engineered bacteria to various chemicals," she explained.
To make the glowing biosensors, Van Dyk and Morgan combined genetic material from Photorhabdus luminescens&endash;a bioluminescent bacterium&endash;with part of the common bacterium, Escherichia coli, or E. coli. Specifically, the researchers fused "glow-making" genes from the luxCDABE group to various E. coli promoters, which respond to damaging environmental threats by triggering the production of new proteins.
The result, Van Dyk said, is that "any stress activates bioluminescence in the resulting cells. The engineered cells emit light in response to protein damage, acidification, exposure to antibiotics and other forms
of stress."
So far, the DuPont/UD research team has subjected a panel of six E. coli biosensor strains to nine chemicals. Some of the chemicals, such as the herbicide, 2,4-dichlorophenoxyacetic acid (2-4D), can be found in the environment. In response to each chemical, the biosensors produced a "characteristic stress fingerprint," Van Dyk said.
The biosensors detect general classes of contaminants, rather than specific chemicals. Van Dyk said she views the technology "mainly as a pre-screening method."
The DuPont Co. holds patents on stress responsive gene fusions to the "glow-making" luxCDABE genes, Van Dyk said. Other DuPont researchers working with Van Dyk included Dana R. Smulski, David A. Elsemore and Robert A. LaRossa.
--Ginger Pinholster
