Ant Farmers Provide New Clues for the Breakdown of Plant Biomass

The Science

Leaf-cutter ants form massive subterranean colonies containing millions of workers that harvest hundreds of kilograms of leaves each year. They use these leaves to grow a mutualistic fungus that serves as the colony’s primary food source. By farming fungus in specialized garden chambers, these dominant Neotropical herbivores facilitate rapid large-scale plant biomass conversion. Using a combination of sugar composition analyses, metagenomics, and whole-genome sequencing, researchers reveal that the fungus garden microbiome of leaf-cutter ants is composed of a diverse community of bacteria with high plant biomass-degrading capacity. show that cellulose and hemicelluloses are degraded in the fungus gardens and that a previously unknown microbial community containing a diversity of bacteria is present. Metagenomic analysis of this community’s genetic content revealed many genes predicted to encode enzymes capable of degrading plant cell walls. The ability of leaf-cutter ants to maintain an external microbial community with high plant biomass-degrading capacity likely represents a key step in the establishment of these ants as widespread, dominant insect herbivores in the Neotropics. This system is an important model for understanding how microbial communities degrade plant biomass in natural systems and has direct relevancy for bioenergy, given recent interest in cellulosic biofuels.


Leaf cutter ants rely on complex farms of bacteria and fungi in their underground nests to deconstruct harvested plant biomass and convert it to food. The communities of microbes responsible for rapid turnover of massive amounts of cellulosic material in tropical ecosystems are poorly understood and could serve as a source of novel microbes and enzymes for industrial biomass conversion. Researchers at the DOE Great Lakes Bioenergy Research Center (GLBRC) and the DOE Joint Genome Institute (JGI) have completed the first microbial community metagenome sequencing project for leaf cutter ant nests. The results reveal a unique community with distinct microbial subpopulations responsible for degrading material of varying degrees of recalcitrance in different parts of the nest. The metagenome library contained gene signatures for a broad range enzymes involved in deconstruction of cellulose, hemicellulose, and other plant polymers. The team has isolated two of the more dominant bacteria found in the ant nests and demonstrated cellulose degradation capabilities.

BER Program Manager

Dawn Adin

U.S. Department of Energy, Biological and Environmental Research (SC-33)
Biological Systems Science Division
[email protected]


Suen, G., J. J. Scott, F. O. Aylward, S. M. Adams, S. G. Tringe, A. A. Pinto-Tomás, C. E. Foster, M. Pauly, P. J. Weimer, K. W. Barry, L. A. Goodwin, P. Bouffard, L. Li, J. Osterberger, T. T. Harkins, S. C. Slater, T. J. Donohue, C. R. Currie. 2010. “An Insect Herbivore Microbiome with High Plant Biomass Degrading Capacity,” PLoS Genetics. DOI:10.1371/journal.pgen.1001129.