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Similar Microbial Carbon Limitation with Soil Depth despite Decreasing Carbon Availability
Seungwon Kim1, Kyungjin Min1,2
1Department of Agricultural Biotechnology, Seoul National University, Seoul 08826, Republic of Korea.
Journal of Microbiology and Biotechnology
|October 19, 2025
Summary
Microbial carbon limitation is common across soils, with microbes utilizing only a small fraction of soil organic carbon. The Michaelis-Menten model effectively estimates this microbial carbon availability and limitation.
Area of Science:
- Soil Science
- Microbial Ecology
- Biogeochemistry
Background:
- Carbon availability controls microbial decomposition and respiration rates.
- Understanding microbial carbon limitation and available carbon pools is crucial but remains unclear.
Purpose of the Study:
- To estimate microbial available carbon and carbon limitation using Michaelis-Menten parameters.
- To investigate how soil organic carbon content influences microbial carbon limitation across soil depths.
Main Methods:
- Employed Michaelis-Menten parameters (Vmax and Km) to estimate available carbon.
- Analyzed soil depth profiles (0-60 cm) at two sites with varying soil organic carbon content.
Main Results:
- Available carbon and soil organic carbon decreased with soil depth at both sites.
- A consistent 0.11% of soil organic carbon was available to microbes.
- The ratio of available carbon to Km was invariant, indicating common carbon limitation.
Conclusions:
- The Michaelis-Menten model is a valuable tool for assessing microbial carbon availability and limitation.
- Microbes utilize a small fraction of soil organic carbon, experiencing similar limitations across different soil types.
- Soil depth and organic carbon content did not significantly alter the relative degree of microbial carbon limitation.
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