Mar. 22, 1999 ANAHEIM, CALIF.--By harnessing glowing bacteria, scientists at the DuPont Co. and the University of Delaware 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 will report March 21 during the American Chemical Society meeting.*
Aflatoxin B1 is produced by molds found in poultry feed, and it "can be of concern for human foods, too," says Van Dyk, a UD graduate who worked with Robin W. Morgan, a professor of animal and food sciences at UD.
The research is fundamental, Van Dyk says, 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 explains.
To make the glowing biosensors, Van Dyk and Morgan combined genetic material from Photorhabdus luminescens--a bioluminescent bacterium--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 says, 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 says.
The biosensors detect general classes of contaminants, rather than specific chemicals. Van Dyk says 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 says. Other DuPont researchers working with Van Dyk included Dana R. Smulski, David A. Elsemore and Robert A. LaRossa.
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