Ants fight pathogenic fungi with a compound from bacteria

A natural product made by bacteria helps thwart pathogenic fungi from destroying Brazilian leaf-cutter ants’ food supply. Researchers led by Mônica T. Pupo, at the University of São Paulo, and Jon Clardy, at Harvard Medical School, recently identified the compound, which they named attinimicin.

Leaf-cutter ants, also known as attine ants, eat fungus that they cultivate in gardens by gathering vegetation to feed the fungus. “We think we invented farming 10,000 years ago. But the ants have been doing their version of farming for some 50 or 60 million years,” Clardy says.

Scientists thought that the ants’ meticulous gardening kept these nests free of fungal pathogens. Recently, however, scientists discovered that the ants are coated in bacteria that contain molecules that fight such fungal invaders. The bacteria give the ants the appearance that “they were dipped in powdered sugar,” Clardy says. Until now, however, scientists hadn’t been able to pinpoint a single, widespread compound produced by the bacteria that had antifungal properties.

Graduate student Taise T. H. Fukuda traveled throughout Brazil and took bacteria from attine ant nests. After studying extracts from the bacteria, she discovered that two-thirds of all the attine ant nests she surveyed had a natural product that had never been identified before—attinimicin (ACS Cent. Sci. 2021, DOI: 10.1021/acscentsci.0c00978).

David H. Sherman, a medicinal chemist at the University of Michigan who studies natural products, calls the work “a fascinating analysis of the emergence of a unique antifungal agent essential for protection of leaf-cutter ants and their food supply across a vast region of the Amazon” in an email.

Although attinimicin is likely too structurally complex to be a good drug candidate, Clardy says that if it has a novel mechanism of action, it might lead to new antifungal therapies.