If you’re unlucky enough to eat a salad contaminated with E. coli, it’s possible that you’ll never know the original source of the bug. After one recent outbreak of illnesses linked to leafy greens that ended in December, the CDC said that its investigation couldn’t identify the specific type or brand that had caused the problem. Even if a farm is flagged as the source, it often takes so long for the investigation to be completed that the lettuce isn’t recalled before consumers eat it.
At a startup called Aanika Biosciences, scientists are working on new technology that can change the process: the tech places invisible, edible microbial tags on each head of lettuce. That makes the tracking process vastly more simple than combing back through records of the produce supply chain on paper, trying to untangle where lettuce came from after it’s been through processing centers that mix greens from multiple farms together.
Right now, it’s nearly impossible to know the source of greens in a particular bag of salad mix sold at a store. “You’ve got a ton of different farms all flowing to a processing plant where it’s washed and packaged, and then that goes to multiple distributors and then thousands of end products and customers,” says Vishaal Bhuyan, cofounder and CEO of Aanika Biosciences. “When you have an outbreak, you can take one step quickly, because you have a serial number on the bag. But once you try to figure out what farms are in that bag, it becomes extremely difficult.”
In one E. coli outbreak in 2018 that killed five people and hospitalized nearly 100, the CDC traced the strain of the bacteria back to the lettuce-growing region near Yuma, Arizona, but couldn’t link it to a single farm, processor, or distributor. In a second outbreak the same year that left a healthy toddler legally blind and unable to speak or move and dozens of other sick, it took a month for the government to link the illnesses to romaine. When they did, they didn’t know the specific source, so they simply told Americans to throw away any romaine lettuce, sending truckloads of food to landfills. Another month later, they linked it to a farm, but they finally concluded that it may have come from multiple farms.
The new technology makes it possible for produce to be tracked in much more detail. “We use a common microbe that in other forms is a probiotic,” says Bhuyan. “It’s very common in the soil, it’s very common in agriculture and animal feed. You can buy it off Amazon.” The company inactivates the microbe so it can’t grow and forms a strong shell around it so it can withstand intense heat and other pressures. Then they make a few edits to the genome of the microbe to create a unique signature that can be assigned to a farm or particular harvest from that farm. (The startup is now working with GS1 US, the organization that administers the UPC code.) The microbial tags can easily be added to a head of lettuce when it’s first washed at a processing center, so the tags end up on every leaf; if it’s later mixed in a bag with greens from another farm, each can be uniquely tracked via a proprietary test. Tracking can also happen immediately, instead of taking weeks to search through antiquated paper records.
There were 40 serious outbreaks of E. coli linked to leafy greens between 2009 and 2018, and the system doesn’t solve the underlying problem. Agriculture needs to do more to prevent lettuce fields from contamination. Often, the issue may be waste from nearby industrial animal farms that leak bacteria into water that’s later used to irrigate lettuce. The government arguably needs to go farther to monitor farms and give fines to those that are causing the problems. Some advocates of indoor farming believe that it’s a better way to grow greens—both because it can save water in drought-prone California and Arizona and because it can eliminate the risk of deadly outbreaks.
Still, for now, there’s a need for a new way to track the outbreaks that are happening, both to help limit illness and to prevent massive amounts of food waste. Aanika is now working to get its technology approved for use in food under the “generally recognized as safe” or GRAS designation and expects approval by the end of the year, at which point it will be ready for the market. “What’s fantastic about this is it’s very usable now,” Bhuyan says. “A lot of synthetic biology stuff is very forward, very out there, and so it’ll take a while. Our technology is actually rather simple.”