Microbial Communities Influence Soil Dissolved Organic Carbon Concentration by Altering Metabolite Composition

Area of Science:

• Soil Science
• Microbiology
• Biogeochemistry

Background:

• Microbial growth during litter decomposition is crucial for soil organic matter (SOM) formation.
• Links between microbial communities, chemical substrates, and carbon storage in soils remain unclear.
• Soil complexity hinders the identification of microbial drivers of decomposition and carbon persistence.

Purpose of the Study:

• To identify microbial taxa and chemical substrates correlated with dissolved organic carbon (DOC) concentration.
• To elucidate the relationships between microbes, soil organic matter, and carbon storage.
• To understand microbial metabolism and its role in carbon persistence.

Main Methods:

• Utilized sand microcosms to control environmental variables and substrate availability.
• Employed Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) to analyze chemical compounds.
• Applied random forest, neural network, and indicator species analyses to identify microbial taxa.

Main Results:

• Protein- and tannin-like compounds strongly correlated with DOC concentration (positive for proteins, negative for tannins).
• Identified 42 bacterial (predominantly Proteobacteria) and 9 fungal (Ascomycota) taxa associated with DOC.
• Microbial consumption of proteins was identified as a significant driver of DOC concentration.

Conclusions:

• Specific microbial taxa and metabolites, particularly proteins, are key regulators of DOC concentration during early litter decomposition.
• This research clarifies the role of microbial metabolism in carbon storage and persistence in soils.
• Findings enhance understanding of the interplay between microbial communities and soil organic matter dynamics.