Differences in substrate use linked to divergent carbon flow during litter decomposition.

Area of Science:

• Environmental microbiology
• Soil science
• Biogeochemistry

Background:

• Soil carbon cycling is crucial for ecosystem function and climate regulation.
• Understanding microbial contributions to soil carbon (C) cycling variation is key for accurate soil C modeling.
• Previous research highlights microbial roles, but specific drivers of divergent C flow remain under investigation.

Purpose of the Study:

• To identify microbial features and processes associated with distinct soil carbon (C) flow patterns.
• To investigate the functional constraints on carbon metabolism within soil microbial communities.
• To link microbial community structure and function to the production of dissolved organic carbon (DOC) and carbon dioxide (CO2).

Main Methods:

• Screened 206 soil communities during plant litter decomposition in a common garden microcosm.
• Measured carbon dioxide (CO2) and dissolved organic carbon (DOC) release over 44 days.
• Utilized fungal and bacterial profiling, metatranscriptomics, RNA-Seq, and machine learning to identify functional traits linked to high and low DOC phenotypes.

Main Results:

• Identified two distinct microbial community groups with 'high' and 'low' dissolved organic carbon (DOC) phenotypes.
• Observed differences in carbon dioxide (CO2) production rates between the two groups, indicating innate metabolic constraints.
• Found variations in substrate use and evidence of organism interactions influencing DOC abundance and community structure.

Conclusions:

• Divergent soil carbon (C) flow patterns are driven by inherent microbial functional traits and community interactions.
• Microbial community structure and function significantly impact the partitioning of carbon into carbon dioxide (CO2) and dissolved organic carbon (DOC).
• These findings provide insights for improving soil C models by incorporating microbial process variability.