RICHLAND, Wash. Leafcutter ants, the tiny red dots known for carrying green leaves as they march through tropical forests, are also talented farmers that cultivate gardens of fungi and bacteria. Ants eat fungi from the so-called fungal gardens, but the bacteria's role has been unclear until now.
New research shows the bacteria help decompose the leaves and play a major role in turning the leaves into nutrients that may be important for both ants and fungi. The findings were published March 1 by The ISME Journal, a publication of the International Society for Microbial Ecology.
"This research provides some of the first tangible details about the fascinating symbiotic relationship between leafcutter ants, fungi and bacteria," said Kristin Burnum, a bioanalytical chemist at the Department of Energy's Pacific Northwest National Laboratory. Burnum is a co-author on the paper and led the study's protein analysis. "Understanding how bacteria turn plant matter into a source of energy in ant fungal gardens could also help improve biofuel production."
The gardens in question are initially sowed by the ants, which bring leaf pieces into their underground nests. From the leaves grow the fungus Leucoagaricus gongylophorus, traditionally thought of as the ants' food. The relationship between leafcutter ants and fungi has been known since 1874, but it wasn't until the late 1990s that scientists started to also identify bacteria in the underground gardens.
Since then, a lively debate has gone on about the bacteria's role. Because pure samples of the garden fungi grown in laboratories don't easily degrade cellulose, a molecule that gives plants structural stability, many scientists have argued the bacteria help decompose the leaves. Other researchers have proposed bacteria like the microscopic bugs in our guts help ants obtain nutrients from the leaves.
Lead author Frank Aylward of the University of Wisconsin-Madiso
|Contact: Franny White|
DOE/Pacific Northwest National Laboratory