Clever ants may hold the secret to antibiotic resistance

Jan 9 2006

New research has revealed that ants that tend and harvest gardens of fungus carry on their bodies a secret weapon, an antibiotic-producing bacteria, which works against the parasites that invade their crops.

The international team of scientists found that the ants accommodate the bacteria in specially adapted cavities on their bodies.

It seems the bacteria thrive on glandular secretions and the discovery indicates that the ants, bacteria, fungus and parasites have been very likely evolving together for tens of millions of years and have what the researchers say is a classic symbiotic relationship.

The researchers led by University of Wisconsin-Madison bacteriologist Cameron Currie say the ants have rapidly adapted to maintain the bacteria and the fact that the species have coexisted for such a long time means there may something there which decreases the rate of antibiotic resistance.

They believe the findings may help solve the significant problem facing modern medicine of resistance to current antibiotics.

Currie and team studied this intricate relationships between certain species of ants in central and South America, the fungus they cultivate for food, the parasite that invades the fungus, and the bacteria that the ants harbor to fight the parasite.

They say it presents a model system with the potential to shed light on the way other organisms interact.

Apparently the ants and their fungus gardens had been closely studied for many years, but Currie is the first scientist to identify the crucial role of bacteria and the antibiotics they produce.

The key insight he made was that white spots on the ants, which were previously dismissed as "waxy blooms," were actually colonies of bacteria.

In this latest phase of his research, Currie and his team removed the external blooms of bacteria from two ant species and examined them with a high-powered microscope.

They discovered 'crypts' attached to endocrine glands, both of which had gone unnoticed by other studies.

The crypts were revealed to be specially adapted to the type of bacteria each species harbors and is evidence that the ants are capable of rapidly changing to maintain their bacterial residents.

Currie says the degree of specialization seen indicates that the association between the ants and the bacteria is ancient and probably vital to the species' survival.

The phenomenon extends to about 210 species of fungus-growing ants, which harbor many different species of a specific group of bacteria.

The study is published in the journal Science.