Navigation Links
Like humans, ants use bacteria to make their gardens grow

MADISON Leaf-cutter ants, which cultivate fungus for food, have many remarkable qualities.

Here's a new one to add to the list: the ant farmers, like their human counterparts, depend on nitrogen-fixing bacteria to make their gardens grow. The finding, reported this week (Nov. 20) in the journal Science, documents a previously unknown symbiosis between ants and bacteria and provides insight into how leaf-cutter ants have come to dominate the American tropics and subtropics.

What's more, the work, conducted by a team led by University of Wisconsin-Madison bacteriologist Cameron Currie, identifies what is likely the primary source of terrestrial nitrogen in the tropics, a setting where nutrients are otherwise scarce.

"Nitrogen is a limiting resource," says Garret Suen, a UW-Madison postdoctoral fellow and a co-author of the new study. "If you don't have it, you can't survive."

Indeed, the partnership between ant and microbe permits leaf-cutters to be amazingly successful. Their underground nests, some the size of small houses, can harbor millions of inhabitants. In the Amazon forest they comprise four times more biomass than do all land animals combined.

"This is the first indication of bacterial garden symbionts in the fungus-growing ant system," says Currie, a UW-Madison professor of bacteriology.

A critical finding in the new study, according to the Wisconsin scientist, is that the nitrogen, which is extracted from the air by the bacteria, ends up in the ants themselves and, ultimately, benefits the nitrogen-poor ecosystems where the ants thrive.

The fungus-growing ants, Currie notes, are technically herbivores. They make their living by carving up foliage and carrying it back to their nests in endless columns to provide the raw material for the fungus they grow as food. "But plant-feeding insects are known to be nitrogen limited," explains Currie, "and the plant biomass nitrogen is lower than what the insects need for survival."

Enter the nitrogen-fixing bacteria, two species of which were isolated in laboratory and field colonies of the ants. But merely finding the bacteria, Suen emphasizes, wasn't enough. It was necessary to prove that the ants were actually utilizing the nutrient to confirm a true mutualism.

"This is important because it could be that the bacteria are fixing nitrogen for themselves and not actually benefiting the ants," says Suen. "Showing that the nitrogen fixed by the bacteria is incorporated into the ants establishes that these bacteria aren't just transient visitors."

One other type of insect, the termite, has been previously shown to utilize nitrogen-fixing bacteria. And other bacteria-ant symbioses have been documented.

However, the discovery of the nitrogen-fixing mutualism in ants has significant ecological implications given the dominance of ants in virtually all of the word's terrestrial ecosystems. The new work suggests that an important source of nitrogen in the American tropics and subtropics is derived through the partnership of ant and bacteria.

Says Currie: "It is possible that this fixed nitrogen can have ecosystem scale impacts."

The partnership with bacteria, which Currie says could extend back to the origins of the gardening ants some 50 million years ago, confers a competitive edge that has permitted the leaf-cutters to prevail in their environments.

Says Suen: "Without nitrogen, there is no way these guys could achieve such large colony sizes. These ants are one of the most dominant insects in the Neotropics. The ability to have colonies with millions of ants is predicted to require a tremendous amount of nitrogen."


Contact: Cameron Currie
University of Wisconsin-Madison

Related biology news :

1. Like humans, monkeys fall into the uncanny valley
2. Key feature of immune system survived in humans, other primates for 60 million years
3. Dogs, humans, put heads together to find cure for brain cancer
4. Why some primates, but not humans, can live with immunodeficiency viruses and not progress to AIDS
5. Like humans, monkey see, monkey plan, monkey do
6. Texas A&M Researchers Examine How Viruses Destroy Bacteria
7. Bacterial ropes tie down shifting Southwest
8. Bacteria launch a shield to resist attack
9. Boston University scientists first to see RNA network in live bacterial cells
10. Eating right, not supplements, is best at keeping your good bacteria healthy, dietitian says
11. Researchers discover RNA repair system in bacteria
Post Your Comments:
(Date:11/19/2015)... Nov. 19, 2015  Based on its in-depth analysis ... recognizes BIO-key with the 2015 Global Frost & Sullivan ... & Sullivan presents this award to the company that ... the needs of the market it serves. The award ... and expands on customer base demands, the overall impact ...
(Date:11/17/2015)... 17, 2015 Paris ... --> Paris , qui s,est ... DERMALOG, le leader de l,innovation biométrique, a inventé le ... et empreintes sur la même surface de balayage. Jusqu,ici, ... l,autre pour les empreintes digitales. Désormais, un seul scanner ...
(Date:11/12/2015)... Mass. , Nov. 12, 2015  Arxspan ... Institute of MIT and Harvard for use of ... discovery information management tools. The partnership will support ... both biological and chemical research information internally and ... will be used for managing the Institute,s electronic ...
Breaking Biology News(10 mins):
(Date:11/25/2015)... Studies reveal the differences in ... pave the way for more effective treatment for one of ...   --> --> Gum ... in cats, yet relatively little was understood about the bacteria ... been conducted by researchers from the WALTHAM Centre for Pet ...
(Date:11/25/2015)... SAN DIEGO , Nov. 25, 2015  Neurocrine ... Kevin Gorman , President and CEO of Neurocrine ... Jaffray Healthcare Conference in New York ... encouraged to visit the website approximately 5 minutes prior ... software.  A replay of the presentation will be available ...
(Date:11/25/2015)... ... November 25, 2015 , ... A ... Black Aerospace Professionals (OPBAP) has been formalized with the signing of a Memorandum ... met with OPBAP leaders Capt. Karl Minter and Capt. Albert Glenn Tuesday, November ...
(Date:11/25/2015)... 25, 2015 The Global ... a professional and in-depth study on the current ... (Logo: ) , The ... including definitions, classifications, applications and industry chain structure. ... international markets including development trends, competitive landscape analysis, ...
Breaking Biology Technology: