The Future of Food

Georgia State scientists have discovered a safe and natural way to delay ripening in fruits and vegetables

its peach season header

From now until Labor Day, George Pierce figures he and the scientists in his lab will eat dozens of the state’s most famous fruit — it’s part of their research.

“We eat a lot of peaches this time of year. Our hands get sticky,” he says.

That’s a sweet perk of some very significant science.

All summer long, Pierce will bring bushels of Georgia peaches and other produce to his lab to continue testing a patented process that has shown, with incredible efficacy, to naturally delay the ripening process in fruits and vegetables.

Pierce and his longtime colleague Sid Crow, both professors of biology, have been studying Rhodococcus rhodochrous, a bacterium common in soil. They’ve found that, under the right conditions, the tiny bacteria can keep all those peaches — or apples, or bananas, or spinach, or even recently cut flowers — fresh for a longer period of time. The process they use to treat the plants is totally natural, without genetic modification and it doesn’t even have to touch the produce to work.

Their discovery has been shown to double the shelf life of certain fruits and vegetables, and it’s also proven to be effective at room temperature, meaning it can save on the cost of refrigeration.

There are other breakthrough applications. Chris Cornelison (M.S. ’11, Ph.D. ’13), a postdoctoral researcher in Crow’s lab, is using the same science to inhibit the growth of fungi responsible for the deadly Chalkbrood disease — a cause of Colony Collapse Disorder — in honeybees and White-Nose Syndrome that’s ravaging North American bats. The U.S. Department of Agriculture says one out of every three bites of food in America rely on the diligent work of bees. Bats play a crucial role in pest control. A single brown bat will eat the equivalent of its body weight in insects in one summer night, Cornelison says.

By preventing waste, improving the consumption of healthy fruits and vegetables, allowing companies to ship produce longer distances and keeping our natural pollinators and pest-eaters healthy, this discovery has the potential to completely change our entire food system, and public health, for the better.

“Simply put, this can affect every person who walks into a supermarket,” says Chester Bisbee, director of technology commercialization and industry relations at Georgia State.

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As ripening begins, many fruits and vegetables produce ethylene, a naturally occurring gas responsible for changes in texture, softening and color during the ripening process. So, when you want to ripen tomatoes, you take five or six and put them in a paper bag.

“This keeps all the gas close,” Pierce says, “and what you find is they all respond in an even, and quicker, way.”

Based on earlier studies, Pierce reckoned that by conditioning Rhodococcus rhodochrous it would produce certain enzymes that would stem the release of ethylene and other gases that signal the ripening process in the plant. A few years ago before the winter break, he set up a handful of experiments placing the enzyme-induced Rhodococcus rhodochrous near different types of fruit to test his theory.

“It worked,” he says. “It worked the first time. And, in scientific experiments, that almost never happens.”

Pierce says the bacteria are part of the beneficial micro-flora that make a healthy and robust plant. In addition to the ability to delay ripening, beneficial microorganisms such as Rhodococcus are capable of inhibiting the growth of unwanted molds and plant pathogens.

“All we’ve done is trick it so it overproduces certain enzymes that heighten its ability,” he says.

The bacteria aren’t being nice. It’s to their benefit, says Pierce. If they can preserve the peach, they can take advantage of this beneficial relationship.

“We’re causing them to work out their own physiology,” he says, “They’re being conditioned to respond.”

Unlike genetically modified organisms (GMOs), which have had their DNA altered in a way that cannot occur in nature, this process tweaks how the wild organisms grow to encourage them to express those enzymes. In other words, in the lab, they’ve created the perfect condition for the bacteria to thrive.

“They’re happy, not stressed. It’s like a spa for bacteria,” Pierce says, laughing.

“It really is like conditioning an Olympic athlete,” adds Crow.

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The Rhodococcus rhodochrous “spa” is on the fourth floor of the Natural Science Center annex. Inside three stainless steel, computer-controlled fermentation tanks are, perhaps, some of the happiest bacteria in the world. They’re fed a steady diet of sugars, proteins and pure oxygen, and, in about three days a suspension of café au lait-colored super Rhodococcus rhodochrous is harvested. Freezing the suspension into bricks then stabilizes the bacteria.

The final application is a catalyst based on those enzymes. Pierce explains the safest way to apply the catalyst is by killing the bacterial cell so it’s not capable of growing or replicating. Killing the bacteria doesn’t affect the activity of the all-important enzymes.

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“So, now, all we’re dealing with is the gases,” Pierce says. “Thus, the catalyst does not have to touch the fruit to work. ”

On the wall in Pierce’s office are side-by-side photos of two, wax-lined cardboard shipping boxes, each holding about 20 peaches. The photo on the left shows the fruit in various shades of grayish-brown and covered in mold. The peaches on the right look ready for a Fourth of July picnic table.

Smiling, Pierce says, “Guess which one has the catalyst in the wax?”

The U.S. Department of Agriculture estimates about 40 percent of harvested produce never makes it to the dinner table because of spoilage, contamination or damage during transport. All along the supply chain — from the farmer, to the wholesaler, to the distributor and to the retailer — the price includes that loss.

Not only can the catalyst be incorporated into the wax coating in individual boxes, it can be sprayed inside of the giant modular shipping containers used when moving produce by truck or rail. And because the catalyst allows for the storage of produce at room temperatures rather than refrigerating it, it can potentially save enormous amounts of energy while the produce is in transit.

There is interest in the invention from businesses all along that supply chain, especially from transportation companies. Pierce says his lab is aggressively moving forward, testing the catalyst before taking it to market, and there are a number of expanded field trials underway.

“Our food system is limited by how far you can ship something,” Pierce says. “Slower ripening means that the food is less susceptible to injury — you bang around peaches in transport, they get moldy. I want people in Minneapolis to eat the tastiest Georgia peaches this summer.


Sid Crow

“Food grown for people to eat that isn’t consumed is a dead loss. We are working on a safe, efficacious way to prolong the life of fruits and vegetables so that people have better nutrition cheaper.”

The university has six patents on the discovery, and six more are in the pipeline.
Bisbee and the newly formed technology commercialization and industry relations group at Georgia State have met with several large corporations to discuss licensing.

“This has far-reaching applications and could have tremendous impact in industry,” Bisbee says.

Pierce, Crow and the scientists in their labs are working to identify those applications. The labs are investigating its effectiveness staving off the growth of mold on corn and grain, as well as how it can prevent the highly contagious banana wilt disease that, in the last decade, has been devastating banana plantations in Africa.

But a grave and unprecedented threat to North American bats might thrust the Rhodococcus rhodochrous into action sooner rather than later.

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Since 2006, White-Nose Syndrome has killed an estimated 6 million bats in the Eastern United States. Last year, the deadly fungal disease was discovered in Georgia. White-Nose Syndrome is named for the way it bleaches bats’ muzzles and wings, and kills its victims by creating enough discomfort to wake the bats during hibernation — when body fat is low and food is scarce — causing them to starve to death. The plague is responsible for the steepest wildlife decline in the past century in North America, according to Bat Conservation International.

By eating bugs that destroy crops and spread disease, bats save the country’s agriculture industry between $4 and $50 billion a year, says the U.S. Geological Survey. They are also voracious predators of mosquitos and pollinators of certain plants.

“If we continue to see declines, we’re going to lose their ecological services and there may be consequences for agriculture and human health,” Cornelison says.

Cornelison, who worked alongside Pierce and Crow throughout development of the catalyst, earning his master’s degree and Ph.D. along the way, is using the discovery to learn how to use anti-fungal treatment based upon Rhodococcus rhodochrous that might be able to save these animals.

Cornelison says his research is ready to go to trial with live, wild bats.

He’s found the bacteria slowed fungal growth and permanently eliminated spore germination on the bats. Like with fruit, it works to prevent the spread of fungi on bat skin without ever touching the animal. This fall, Cornelison will work with the Tennessee Nature Conservancy to treat bats in abandoned military bunkers and mine shafts.

In addition, he’s learned that Rhodococcus rhodochrous is effective in fighting Chalkbrood disease, a fungal disease that infects bees in the larval or juvenile stage. Chalkbrood disease in bees has contributed to the number of managed honeybee colonies in the U.S. being cut in half, a phenomenon known as Colony Collapse Disorder.

He’s seeking a benign alternative to anti-fungal drugs, which are expensive and can make honey inedible. So far, he has achieved positive results in cell studies, and no negative effects were found in toxicity trials exposing bees to the bacteria in the air or in their honey.

Pierce and Crow see Cornelison’s work as just one bootstrap from their potentially world-changing invention, and they’re taking steps to pass along that knowledge, one generation of scientists at a time.

“We’re training a whole new group we hope will inherit this, run with it and populate this industry,” says Pierce.

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