Symbiotic nitrogen fixation in the fungus gardens of leaf-cutter ants

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Symbiotic nitrogen fixation in the fungus gardens of leaf-cutter ants

Publication Type:

Journal Article

Source:

Science, Volume 326, Number 5956, p.1120-1123 (2009)

Keywords:

Deconstruction

Abstract:

Bacteria-mediated acquisition of atmospheric N2 serves as a critical source of nitrogen in terrestrial ecosystems. Here we reveal that symbiotic nitrogen fixation facilitates the cultivation of specialized fungal crops by leaf-cutter ants. By using acetylene reduction and stable isotope experiments, we demonstrated that N2 fixation occurred in the fungus gardens of eight leaf-cutter ant species and, further, that this fixed nitrogen was incorporated into ant biomass. Symbiotic N2-fixing bacteria were consistently isolated from the fungus gardens of 80 leaf-cutter ant colonies collected in Argentina, Costa Rica, and Panama. The discovery of N2 fixation within the leaf-cutter ant-microbe symbiosis reveals a previously unrecognized nitrogen source in neotropical ecosystems.