A Detailed Look at How Ants’ Fungal Gardens Break Down Plant Litter
Researchers developed a novel approach to map how a community of leaf-cutter ants, fungi, and bacteria work together to break down plant biomass.
The Science
Scientists have found many ways to break down materials from plants to turn them into useful products. But a material in plants called lignin has remained incredibly difficult to break down without sending pollutants to the environment. Lignin is a very strong material that is key to wood and other structural parts of plants. Scientists know that communities that consist of leaf-cutter ants, fungi, and bacteria break down lignin in the environment. These communities are complex and hard to study. To address this problem, researchers developed an approach called metabolome-informed proteome imaging (MIPI) that allows them to peer down to the molecular level to study each stage of the breakdown process in detail. With this approach, scientists found that these communities have enzymes that break down carbohydrates and lignin. These enzymes indicate a prominent role for fungi in the decomposition of plant material. The approach also provided a comprehensive view of the biological pathways underlying this decomposition process.
The Impact
Fungal communities have a complex mix of organisms and molecules. This makes them difficult to study. Prior to the development of MIPI, researchers had to use more traditional methods that measure the primary components of the entire environmental sample. These traditional methods do not tell the researchers about each component within a system. With MIPI, they can identify the exact location and abundance of plant polymers and materials left from organisms’ breakdown of food and other substances. MIPI also allows scientists to home in on these locations to identify and characterize enzymes that are highly relevant for biotechnological applications.
Summary
A team of researchers from Pacific Northwest National Laboratory performed high-resolution imaging across thin sections of the fungal gardens that the leafcutter ant species Atta cephalotes builds for food. The scientists applied a metabolome-informed proteome imaging (MIPI) approach to map lignin degradation. MIPI combines two mass spectrometry techniques that detect proteins and metabolites and also provide information on the location of proteins and metabolites within the sample. This allowed the researchers to visualize which of those metabolites and proteins were close to each other in the fungal garden. The combined locations of these components indicated hot spots where plant material was being broken down. The team then focused on those regions to view specific enzymes involved in the process. Knowing the type and location of the enzymes allowed the researchers to determine which microbes were a part of the degradation process.
These findings together confirmed that a fungus is the primary degrader of the plant material in the ants’ gardens. The team also determined that bacteria present in the system transformed previously digested plant polymers into nutrients such as vitamins and amino acids that are used by the fungus. These components benefit the entire ecosystem by accelerating fungal growth and plant degradation. The new technique also helps reveal biomolecular pathways vital to the plant degradation process, aiding in the fundamental understanding necessary for developing future bioproducts and the bioeconomy.
Contact
Kristin Burnum-JohnsonPacific Northwest National Laboratory
[email protected]
Funding
This work was funded by the Department of Energy Office of Science, Biological and Environmental Research program’s Early Career Research Program award to Kristin Burnum-Johnson. A portion of this research was performed at the Environmental Molecular Sciences Laboratory, a Department of Energy Office of Science user facility sponsored by the Biological and Environmental Research program. Additional funding was provided by the National Science Foundation and the National Institutes of Health.
Publications
Veličković, M., et al., Mapping microhabitats of lignocellulose decomposition by a microbial consortium. Nature Chemical Biology 20, 1033–1043 (2024). [DOI: 10.1038/s41589-023-01536-7]
Related Links
How Leafcutter Ants Cultivate a Fungal Garden to Degrade Plants and Provide Insights into Future Biofuels, Pacific Northwest National Laboratory news
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