Spray-on DNA bar codes help trace food-borne illnesses
Featured in The Genetic Literacy Project
Date: November 14, 2014
In the field of forensics, DNA profiling has solved many whodunits over the last forty years. Find a hair on the carpet near the bloodied victim, send it to the labs for testing and compare it to the DNA profiles of known criminals — If the detective finds a match, voila, the crime is solved.
Now scientists are using DNA techniques on errant vegetables, ones that have carried food-borne bacteria and other contaminants such as Salmonella into the homes of their unsuspecting victims. But, in this case, the question’s not so much “whodunit” (the cider in the kitchen with the E. coli) as it is where the contaminated foods originated.
Take the listeriosis outbreak from contaminated melons that killed 30 people in the U.S. in 2011. The key to stopping further fatalities was finding out where those melons came from and alerting people who might have purchased melons from the same place. Who were the growers and what was the distribution chain? (The lines between farm and consumer in the modern world can be very long and very twisted, it’s hardly ever as simple as pointing to a farm down the street from those who become ill.)
By the time people start feeling the symptoms of Salmonella or E. coli poisoning, tracing the origin of the contamination might be tricky, time consuming and expensive. The store may receive produce from multiple farms and have already disposed of shipment boxes. The contamination might not even have occurred on the farm, but somewhere en route as part of the distribution process. But a Californian start-up, DNATrek, has come up with a solution to this conundrum: spray-on DNA barcodes.
In the labs at DNATrek, the scientists create different liquids that each contain a unique DNA sequence. The sequences would be combined with safe-to-eat food additives, such as the waxes that are now sometimes added to the surfaces of apples and cucumbers. Growers, packers, shippers and others in the supply chain would spray food with their unique liquid formulation—stamping the produce with their signature genetic bar code.
If needed in the case of an outbreak, investigators could use polymerase chain reaction technology to decipher the bar code and determine where the produce was grown and what route it had traveled. According to Anthony Zografos, founder and CEO of DNATrek:
If there’s a problem at home and there’s a piece of the cantaloupe left, you can pick it out of the trash, you can scrub the surface, and all the available information is there and you know exactly where it came from.
In only 15 to 20 minutes, scientists would be able to find out all the particulars of the produce. In an outbreak, time is of the essence; lives could be saved. And the technology is relatively inexpensive too. The spray will probably cost $1 for every 1,000 pounds of produce. Compare that to the estimated $150 billion a year that the U.S. directly or indirectly, spends on food-borne illnesses in a year.