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Tending a garden

Sept. 10, 2013 - Agriculture is thought to be a primarily human endeavor, but some animals do engage in some agriculture-themed pursuits – none more so than leaf-cutter ant – which cut plant material and place them into aptly named fungus gardens. The ants don't eat the plants, but instead eat the fungus that grows on the partially chewed plant matter.

Frank Aylward, a bacteriology graduate student at University of Wisconsin-Madison, decided to look to nature to find new and improved ways to degrade plant cell walls to gain access to the sugars necessary to make biofuels.

"A huge barrier to the production of biofuels if the degradation of plant biomass, because it is full of cellulose, hemi-cellulose and a lot of other compounds that are difficult to break down," he said. "And since leaf-cutter ants derive energy from plant biomass, we wanted to determine how they were doing that, what enzymes they were using, etc."

The fungus grown by these ants is Leucoagaricus gongylophorus, and Aylward and his fellow researchers sequenced its DNA to determine what enzymes it uses to break down plant material.

"The genome of this fungus is completely new," he said. And while other microbes use similar methods of action or related enzymes, Aylward says that these newly discovered enzymes could be potentially much more efficient.

"We hope that these enzymes will be a little bit more efficient, and by potentially creating cocktails of the enzymes and mixing them with others, the maybe we can boost efficiency."

The next step in the research is to directly analyze how the new enzymes affect biofuel production by mimicking the industrial process.

According to Aylward, in the biofuel industry, a "cocktail" of enzymes from microbes is used to break down plant biomass in order to release the sugars. He believes that these newly discovered enzymes from the L. gongylophorus fungus could augment or replace those already in the cocktail and boost overall efficiency of the process.

Additionally, while bacteria are not directly involved with breaking down the plant biomass, they are present in the fungus gardens and could therefore have some role in the process. "If you go out into nature," he said, "you never really see one organism breaking down plant biomass alone – it is always happening in a community.

"There are a lot of different microbes that co-exist and are doing that process in a variety of ecosystems, not just fungus gardens."

September 10, 2013  By David Manly