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Acne Bacteria Found in Grapevines

FILE - Scientists were surprised to find the grapevines they studied harbored Propionibacterium acnes, a bacterium usually found on human skin and best known for causing acne.
You may think your teenage acne lasted a long time, but scientists have discovered grapevines have been carrying the bacteria that cause pimples for 7,000 years.

Named for the musical iconoclast Frank Zappa, scientists say it is the first time a bacterium found in humans has been discovered taking up residence all the way across the tree of life in plants.

Molecular biologist Omar Rota-Stabelli at Italy’s Fondazione Edmund Mach and colleagues were studying microbes living inside grapevines.

“There’s plenty of bacteria living inside plants,” he said. “And we know some are good bacteria for the plants. Some others are bad. Our study [aims] to understand what lives inside and if it's giving an advantage or not."

They were surprised to find that all the grapevines they studied harbored Propionibacterium acnes, a bacterium usually found on human skin and best known for causing acne.

The findings are published in the journal Molecular Biology and Evolution.

Bacteria inside plants

P. acnes doesn’t give grapevines acne. At this point, it’s not clear what the bacteria is doing to, or for, the plant.

It’s not that uncommon to find human-associated bacteria on plants. Take, for example, E. coli, which usually inhabits the guts of humans and animals, but can contaminate fruits and vegetables and cause disease.

But those bacteria rarely stay for long. This strain of P. acnes appears to be living, among other places, inside cells in the center of the grapevine, called pith. And it appears to have lost a critical DNA repair protein, which makes it hard to survive on the outside.

“This bacteria seems perfectly used to staying in the grapevine. It can’t live without [the] grape,” Rota-Stabelli said.

Prehistoric meeting

The scientists determined that the bacteria and the grapevine probably first got together about 7,000 years ago, which “perfectly matched when humans domesticated the grape. So, it really made sense,” he said.

Tending grapevines involves a lot of cutting, he said, opening up a route for the bacteria to move in.

And pith cells are rich in fatty acids.

“These bacteria probably feed on those fatty acids, as they used to do on our skin,” he said.

When they first discovered P. acnes in their grapevines,

"My impression was, 'that’s contamination from the technician. No way,’” Rota-Stabelli said.

The technician was not especially acne-prone.

“No, he’s very hairy,” Rota-Stabelli joked.

The Zappa Way

When further tests confirmed it was, in fact, P. acnes, they named it type Zappae, after the virtuoso musician known for such songs as, "Don’t Eat the Yellow Snow" and "My Guitar Wants to Kill Your Mama."

Rota-Stabelli says he and lead author Andrea Campisano are fans. But it’s more than that.

“I think we behaved in a Frank Zappa way,” he said. Instead of assuming the samples were contaminated, “we thought in a different way and found something very unexpected.”

The next step is to look inside other plants to see if P. Zappae turns up in more unexpected places.
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    Steve Baragona

    Steve Baragona is an award-winning multimedia journalist covering science, environment and health.

    He spent eight years in molecular biology and infectious disease research before deciding that writing about science was more fun than doing it. He graduated from the University of North Carolina at Chapel Hill with a master’s degree in journalism in 2002.

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