Researchers say bacteria have been developing copper resistance for thousands of years. Photo by Juan Gaertner/Shutterstock

COLUMBUS, Ohio, March 16 (UPI) -- New research suggests bacteria have been evolving resistance to copper's antibacterial properties since the Bronze Age.

Copper and its derivatives have bacteriostatic qualities, the ability to stop bacteria from reproducing. Copper-alloy surfaces are able to thwart a range of microbes, and human immune systems even use small amounts of copper to stymie microbes.


But microbes aren't going quietly. Bacteria are constantly adapting to better combat environmental threats.

Researchers at Ohio State University showed that copper-resistant genes became more prominent among strains exposed to copper-rich environments.

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When scientists traced the genetic history of common bacteria, like E. coli, they found genetic diversification corresponded with peak years in copper production.

"This may have arisen at the time that humans started using a lot of copper -- in the Bronze Age," Jason Slot, an assistant professor of plant pathology at Ohio State, said in a news release.

Slot is the lead author of a new study on bacterial resistance to copper bacteriostatic power, published this week in the journal Genome Biology and Evolution.

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Bacteria may have first begun adapting their genes in milk fermented in copper vats. Ever since, Slot and his colleagues speculate, microbes have been slowly building up their genetic defenses against the metal.

As bacteria becomes more resistant to copper, copper-rich environments may become a liability. Copper is currently widely used for animal feed and in many medical devices.

"You're enticing the bacteria in the environment to develop a mechanism that evades your immune system," Slot said. "I think overuse of anything is a bad idea, but it's really hard for people not to overuse the few weapons that we have."

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