Functional and Systems Biology
Microbes and their Metabolites Affect Soil Dissolved Organic Carbon
New research shows how microbes producing or decomposing certain metabolites affect dissolved organic carbon concentration in soils.
How the billions of microbes that call soil home affect carbon storage isn't fully understood. This study identified 42 bacterial and 9 fungal taxa relevant to this process, improving understanding of soil microbe and carbon connections. (Illustration by Stephanie King | Pacific Northwest National Laboratory)
The Science
Soil is an important global storehouse for carbon. Carbon dioxide, or CO2, is removed from the atmosphere and held in the Earth. Despite soil's key role in carbon storage, exactly how the billions of microbes that call it home affect this process isn't fully understood. New research links the amount of carbon in soil to microbes producing and breaking down specific end-products of metabolism, known as metabolites. This work helps improve understanding of the connection between soil microbes and soil carbon content.
The Impact
The release of CO2 into the atmosphere has an important effect on climate change, making investigating how microbes affect CO2 retention in soils vital to improving overall understanding of climate change. The amount of carbon stored in the soil depends on the physical structure of the soil itself, what compounds are present, and how microbes present in the soil are functioning.
This research closes a major gap in this area by identifying connections between metabolites, microbes, and carbon flow during the first stages of plant litter decomposition.
Summary
Although microbes and their rapid growth during the early phases of plant litter decomposition are important aspects of soil organic matter formation, the connection between microbial taxa, their metabolites, and carbon storage is not well understood. The microbial communities and variations in chemical composition in soils are complex, making these connections difficult to define. To address these challenges, this study used sand microcosms to control external environmental factors, including temperature, moisture, and carbon availability. Fourier transform ion cyclotron resonance mass spectrometry was used to examine microcosm samples taken during early-phase plant litter decomposition, and protein- and tannin-like compounds demonstrated the strongest correlations to concentrations of dissolved organic carbon (DOC). While proteins exhibited positive correlations with DOC, tannins correlated negatively.
This study identified 42 bacterial and 9 fungal taxa connected to DOC. Most of the bacterial taxa were of the phylum Proteobacteria, while all fungal taxa were of the phylum Ascomycota. There were also significant connections between microbes and protein-like compounds, suggesting that microbial consumption of proteins drives DOC. This research shows clear links between DOC concentration and microbial production and decomposition of certain metabolites, contributing to the understanding of how microbes affect carbon fate.
Contacts
Marie Kroeger
Los Alamos National Laboratory
Vanessa Bailey
Pacific Northwest National Laboratory
John Dunbar
Los Alamos National Laboratory
Funding
This work was funded through a Department of Energy, Biological System Science Division Science Focus Area grant. Additional funding was provided through EMSL, the Environmental Molecular Sciences Laboratory, a DOE Office of Science, Biological and Environmental Research program user facility.
Publication
T.P. Campbell, et al., "Microbial Communities Influence Soil Dissolved Organic Carbon Concentration by Altering Metabolite Composition." Frontiers in Microbiology 12, 799014 (2022). [DOI: 10.3389/fmicb.2021.799014]