Brazilian ant farm yields new antifungal compound

Fungus-growing ants, found throughout the Americas, may prove to be a source of medically useful compounds, researchers say. Photo by Hectonichus/Wikimedia
Fungus-growing ants, found throughout the Americas, may prove to be a source of medically useful compounds, researchers say. Photo by Hectonichus/Wikimedia

Jan. 20 (UPI) -- Scientists have discovered a unique metabolite molecule utilized by a diversity of attine ants, or fungus-farming ants, in Brazil.

The the new molecule, attinimicin, described Wednesday in the journal ACS Central Science, is structurally too complex to serve as a useful drug model.


Scientists say they are hopeful, however, that ongoing surveys of attine ant farms will eventually reveal medically useful compounds.

"We've discovered several antifungal metabolites, like selvamicin, that have garnered significant interest, however it is an uphill climb to get anything into the clinic," study co-author Emily Mevers, who conducted the research while working as a postdoctoral fellow at Harvard Medical School, told UPI in an email.

Fungus-farming ants are one of many groups of organisms, including beetles, termites, sponges and squid, that use symbiotic relationships with microbes to chemically defend themselves.

Attine ants don't use microbial communities to protect themselves, exactly -- they rely on them to protect their crops.

"The main role of the bacteria in the ant system is to protect the cultivar, food fungus, from getting contaminated by the pathogenic fungus," said Mevers, now an assistant professor of chemistry at Virginia Tech.


Fungus-farming ants throughout the Americas have been found to utilize similar combinations of bacteria strains. However, scientists have been flummoxed by the structural diversity of metabolites produced by attine ant bacteria.

"Over the years we have learned that the machinery that encodes the production of these small molecules can easily be swapped -- horizontal gene transfer -- so bacteria can easily test out a new metabolite," Mevers said. "It appears that the bacteria that live on the ants are very good at testing out their neighbors' small molecules and this is the main driver of the observed diversity among the small molecules they produce."

"Horizontal gene transfer is much quicker than having the bacterium evolve a new molecule from scratch," she said. "That is what makes the attinimicin story so unique and really tells us that attinimicin has an important ecological role in this system."

The discovery of attinimicin marks the first time scientists have identified a metabolite molecule shared by distinct, geographically disparate groups of attine ants.

In lab tests, researchers found attinimicin provided antifungal activity, protecting food fungus from fungal parasites.

However, unlike antibiotics, attinimicin was only able to offer its protective qualities in the absence of iron. Attinimicin also worked to rid mouse models of a Candida albicans infection.


Inspired by the discovery of the broadly distributed metabolite, researchers plan to continue probing attine ant colonies and their fungus farms for medically relevant compounds.

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