Inside Withers Hall, Dr. Jon Allen is poisoning milk. Likewise, in Riddick Hall, Dr. Orlin Velev is tainting water. And in a sprawling lab complex on Varsity Drive, Dr. Lee-Ann Jaykus is trying to manipulate the genes of microorganisms like Salmonella and E.coli.
None of these scientists is engaged in a sinister plotjust a concerted effort to foil one. With bioterrorism a looming national threat, NC State researchers are taking the University’s traditional land-grant mission of helping farmers to a new level to protect the U.S. food supplyand consumersfrom contamination.
“There’s no difference between food safety, which we’ve studied at the University for years, and food security, except for the malicious intent and possibly larger scope involved with bioterrorism,” says Jaykus, an associate professor of food science. “Any normal food safety agent can be an effective bioterror tool. It’s pretty easy to get a culture of Salmonella and spread it around.”
But the enormous quantity of food constantly moving through the processing pipeline creates a needle-in-the-haystack situation for inspectors trying to catch adulterated products. Current detection techniques in which samples taken at various stages of production are cultured and examined for foreign substances can take anywhere from two days to two weekstoo long a delay at security checkpoints. So Jaykus, who specializes in finding “bugs” in food, and Allen, a food science professor who spends most of his time making milk more nutritious, are working on real-time systems to detect biological and chemical contamination.
Instead of waiting for a culture to grow, Jaykus is using a grant from the North Carolina Agricultural Foundation to see if polymerase chain reaction (PCR), a method of rapidly copying DNA, can produce a test for the presence of bacteria. PCR amplifies the genetic material found in a small food sample so it becomes large enough to check for targeted pathogens. Because the fats and proteins in food can interfere with the test, she wants to refine the technique further, and she continues to look for a “universal primer,” a sequence of nucleic acids found in most bacteria, to make it easier to screen for contamination. “It basically comes down to adapting a molecular biology test used in health care settings for a food and environmental matrix,” she says.
Because milk is such a perishable commodity, the dairy industry has installed extensive testing to detect everything from spoilage to penicillin. The latter sometimes gets into the milk supply when a lactating cow is treated for an infection. One such safeguard is tucked into the corner of a basement at the College of Veterinary Medicine, where Dr. Ron Baynes and other pharmacologists man the hotline of the Food Animal Residue Avoidance Databank (FARAD).
Operated in conjunction with the University of California-Davis and the University of Florida, FARAD tells farmers and veterinarians nationwide how long many chemicalsusually drugs or pesticidesremain in an animal’s system so they know when it will be safe to sell the milk or slaughter the animal for meat. When no labeling information is available to determine how specific drugs are metabolized, Baynes and his colleagues use a special algorithm to predict a safe interval to withhold the animals from the market. “It goes beyond public health issues,” Baynes says. “If meat were to make it into the system before contamination was discovered, it would severely damage consumer confidence. Just look what Mad Cow Disease has done to other economies.”
While FARAD and routine testing provide protection against threats to milk from most biological contamination and some chemicals, no protections exist against chemical toxins like cyanide, says Allen, who is using a grant from the North Carolina Dairy Foundation to develop such a test. He adds tainted milk samples to human cell cultures to record the response. “The cells require so many things to stay alive that, if anything is blocked, you see an immediate impact,” he says. He hopes to link his assay to a color strip or meter for easy reading of results and says the test could be adapted for use with other foods as well.
Velev, a chemical engineering assistant professor, is using biology as well as chemistry to create a sensor for detecting contaminated water supplies. He assembles gold particles into nanometer-sized structures that capture molecules as they flow past in running water. He then shoots a laser at the gold and measures the intensity of the scattered light to determine what contaminants are present in the water. Velev also is looking at using yeast cells as a possible sensor by measuring the electrical change in yeast cultures when they are exposed to various chemicals. “You need an interdisciplinary approach to solve these problems,” he says. “One field of science isn’t going to be successful on its own.”