Permafrost peatlands are large carbon pools and sensitive to global warming. Thawing of permafrost soils under warming release carbon dioxide and methane to the atmosphere due to enhanced microbial mineralization of soil organic carbon. However, how soil microbial fixation carbon in permafrost peatlands remains a huge research gap.

Recently, researchers at the Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, quantified the rates of soil microbial carbon fixation in different types permafrost peatland and identified the active microorganisms involved in the fixation of CO₂ to soil organic carbon.  

This work was published in the journal of Applied Soil Ecology on November, 2025.

The researchers found that soil microbial carbon fixation rate in the active layer of continuous permafrost and discontinuous permafrost peatland were higher than in permafrost layer, indicating that soil microbial carbon fixation will increase upon thawing of permafrost, therefore will affect soil carbon balance. The abundance of ¹³C labeled Comamonadaceae, Sphaerotilaceae, and Beijerinckiaceae positively correlated with soil microbial carbon fixation rates in continuous permafrost, discontinuous permafrost, and seasonally frozen peatlands, respectively. Structural equation modeling analysis showed the soil microbial C-fixation rates were primarily controlled by RubisCO activity. Whilst, the soil water content, total carbon, and microbial biomass carbon served as the main positive factor via an indirect pathway. These results are needed to understand the mechanisms underpinning carbon fixation and its potential role in the sequestration of soil carbon.

Keywords:

Permafrost type; Peatland; Microbial C-fixation; RubisCO; cbbL gene

Figure 1. Relative abundance of soil carbon fixation microbe at family level

Figure 2 Structural equation modeling describing the soil microbial abundance and enzyme activity in affecting the soil microbial carbon fixation.

This research was supported financially by the National Natural Science Foundation of China (42220104009, 42494824, 42271109).

Contact:

Song Yanyu

Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences

E-mail: songyanyu@iga.ac.cn

Attachment:

Soil CO₂-fixation by cbbL-harboring microorganisms in different types of permafrost peatlands

https://doi.org/10.1016/j.apsoil.2025.106639