Ants used antibiotics long before humans did

Tom Arnold
National Post

Fungus-growing ants in Panama have given Canadian scientists new clues about antibiotics.

"This is a case where we now find that ants have been making use of bacteria for the production of antibiotics to treat diseases long before humans have," said Cameron Currie, the study's principal investigator and a graduate student in the department of botany at the University of Toronto.

Currie and his team of university researchers discovered that the partnership between the attine ants and an antibiotic-producing bacterium is about 50 million years old. Their findings are published in today's issue of Nature.

Attine ants live in the tropics of South and Central America, as well as some areas of North America. They grow a fungus that they feed on and that is essential for their survival. Without the fungus to sustain them, the ants would die. The relationship between the ants and the fungus has long been seen as a symbiotic one. But the researchers found a third essential element.

In studying 22 different species of attine ants in Panama in 1997 and 1998, the researchers discovered that a bacterium -- carried by the ants on their backs -- is key to maintaining the partnership. This bacterium produces an antibiotic that targets parasites that can invade the fungus.

This study is considered significant because about 80% of antibiotics used by humans come from the same group of bacteria -- Streptomyces -- that the fungus-growing ants carry around.

"The antibiotics that we use have all devolved from bacteria and fungi," said Currie. "We've discovered and made use of these for our medical use while these ants, millions of years ago, discovered through evolution that these microbes can benefit them by helping them protect their fungal gardens."

In addition to broadening our understanding of antibiotics, Currie thinks the ants may help us learn how to combat diseases resistant to antibiotics.

"This relationship is an ancient association among these organisms. There is a co-evolutionary arms race between the parasite on the one side, and the ant and their antibiotic-producing bacteria on the other," Currie said.

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