Microbial autotrophy explains large‐scale soil CO₂ fixation

Abstract

Microbial communities play critical roles in fixing carbon from the atmosphere and fixing it in the soils. However, the large-scale variations and drivers of these microbial communities remain poorly understood. Here, we conducted a large-scale survey across China and found that soil autotrophic organisms are critical for explaining CO 2 fluxes from the atmosphere to soils. In particular, we showed that large-scale variations in CO 2 fixation rates are highly correlated to those in autotrophic bacteria and phototrophic protists. Paddy soils, supporting a larger proportion of obligate bacterial and protist autotrophs, display four-fold of CO 2 fixation rates over upland and forest soils. Precipitation and pH, together with key ecological clusters of autotrophic microbes, also played important roles in controlling CO 2 fixation. Our work provides a novel quantification on the contribution of terrestrial autotrophic microbes to soil CO 2 fixation processes at a large scale, with implications for global carbon regulation under climate change.

Global variations and controlling factors of anammox rates

“…Meanwhile, Lotti et al (2014) found that 0.72 mol C was fixed via the acetyl-coenzyme A pathway with 1 mol of N 2 production over the anammox process. Carbon sequestration through the anammox process may be partly responsible for the missing C sink in terrestrial ecosystems, which may itself be an attractive area of study (Liao et al, 2022). The magnitude and kinetics underlying the impacts of the anammox process on C cycling remain to be investigated in future studies.…”

Effect of soil flooding and drying on the metabolic pathways of CO2 fixing microorganisms along an elevation gradient in the Three Gorges Reservoir drawdown area

“…The Calvin cycle being a more ATP‐consuming pathway, and its energy consumption (2 ATP), may explain why the rTCA cycle is the preferred metabolic pathway in the nutrient‐poor drawdown area soils, whereas the Calvin cycle would be favoured in agricultural or forest soils (Liao et al., 2023). Notably, despite the Calvin cycle having lower abundance than that of the rTCA cycle in the drawdown area of the Three Gorges Reservoir, the abundance of the Calvin cycle and its key gene, cbb L, showed significant variations (Figure 4).…”

“…In terrestrial ecosystems, CFMs are estimated to sequester ca. 4.9 Pg of carbon annually (Huang et al, 2022), making their carbon fixation function crucial for greenhouse gas regulation, soil carbon uptake and global carbon cycling (Liao et al, 2023;Mahmoudi & Wilhelm, 2023). Among the eight major carbon fixation pathways identified in nature, the Calvin cycle is the primary pathway for microbial assimilation of CO 2 (Berg, 2011).…”

Low Carbon Loss from Long-Term Manure-Applied Soil during Abrupt Warming Is Realized through Soil and Microbiome Interplay

“…This shift in the relative abundance was coupled with an increase in the relative abundance of Thaumarchaeota in the warm-stimulated community. Soil autotrophic organisms are crucial in explaining CO 2 fluxes from the atmosphere to soils . Thaumarchaeota are primarily responsible for the widespread occurrence of chemolithoautotrophic ammonia oxidation, effectively fixing CO 2 and producing organic matter in soils. − Using qSIP, our previous research has established that Thaumarchaeota could assimilate 13 CO 2 derived from 13 C-labeled plant residue in arable soil .…”