Composition and carbon-fixation pathways of carbon-fixing microorganisms in soils of a typical steppe and desert steppe in Inner Mongolia

doi:10.11686/cyxb2024476

Abstract

Abstract:

Autotrophic soil microbes can assimilate atmospheric CO₂ and fix carbon into the soil. The relative contributions of soil microorganisms to carbon fixation are greater in arid regions than in humid ecosystems. However， current carbon-fixation models mainly focus on plant functions and often neglect the roles of soil autotrophs. Therefore， such models cannot accurately predict carbon sequestration in the soil of arid ecosystems. In this study， we focused on the soil microorganisms of the typical steppe and desert steppe in Inner Mongolia， and analyzed differences in the composition and metabolic pathways of carbon-fixing microbial communities in those soils. The main results were as follows： 1） There were 14 carbon-fixing microbial groups （classes） in soils of both categories of steppe， among which Acidimicrobiia， γ-Proteobacteria， and Chloroflexi showed significantly higher abundance in the desert steppe soil than in the typical steppe soil； 2） The relative abundance of genes related to the reductive citric acid （rTCA） cycle and the 3-hydroxypropionate （3-HP） cycle was significantly higher in the desert steppe soil than in the typical steppe soil； 3） The abundance of genes encoding key enzymes in the rTCA pathway ［EC （1.2.7.1） and EC （1.2.7.3）］ and the 3-HP pathway ［EC （6.4.1.2） and EC （6.4.1.3）］ was higher in the desert steppe soil than in the typical steppe soil. Clearly， the abundance of carbon-fixing microorganism classes， carbon-fixation pathways， and genes encoding their key enzymes was higher in the desert steppe soil of Inner Mongolia than in the typical steppe soil， indicating that the desert steppe soil microorganisms have stronger potential for atmospheric CO₂ fixation.

Key words: grassland soil, carbon-fixing microorganisms, carbon-fixation pathways, metagenomics, relative abundance

Hao PENG, Bao-zhu DONG, Li-juan MA, Xiao-dong YU, Yi-fan ZHANG, Xiao-fang LI. Composition and carbon-fixation pathways of carbon-fixing microorganisms in soils of a typical steppe and desert steppe in Inner Mongolia[J]. Acta Prataculturae Sinica, 2025, 34(8): 123-131.

Figures/Tables 5

References 36

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采样点Sampling points	荒漠草原 Desert steppe	典型草原 Typical steppe
1	110°36'34.4'' E，41°52'18.1'' N	117°41'16.5'' E，44°54'17.2'' N
2	111°5'16.4'' E，41°47'8.5'' N	118°34'32.1'' E，45°5'26.9'' N
3	111°37'0.5'' E，41°41'58.4'' N	117°29'7.9'' E，45°30'57.5'' N
4	111°52'44.3'' E，41°52'18.1'' N	118°29'0.9'' E，45°47'13.1'' N
5	110°50'5.7'' E，41°20'5.5'' N	119°10'24.6'' E，46°9'55.3'' N
6	112°10'40.5'' E，42°26'17.1'' N	119°37'35.3'' E，45°47'34.4'' N

采样点Sampling points	荒漠草原 Desert steppe	典型草原 Typical steppe
1	110°36'34.4'' E，41°52'18.1'' N	117°41'16.5'' E，44°54'17.2'' N
2	111°5'16.4'' E，41°47'8.5'' N	118°34'32.1'' E，45°5'26.9'' N
3	111°37'0.5'' E，41°41'58.4'' N	117°29'7.9'' E，45°30'57.5'' N
4	111°52'44.3'' E，41°52'18.1'' N	118°29'0.9'' E，45°47'13.1'' N
5	110°50'5.7'' E，41°20'5.5'' N	119°10'24.6'' E，46°9'55.3'' N
6	112°10'40.5'' E，42°26'17.1'' N	119°37'35.3'' E，45°47'34.4'' N

固碳微生物分类（纲） Carbon-fixing microorganisms （class）	典型草原 Typical steppe	荒漠草原 Desert steppe
古细菌Archaea
亚硝化球菌纲Nitrososphaeria	0.389±0.203	0.571±0.284
热原体纲Thermoplasmata	0.003±0.000	0.003±0.001
深古菌纲Candidatus_Bathyarchaeota	0.003±0.002	0.003±0.001
热变形菌纲Thermoprotei	n.d.	n.d.
古丸菌纲Archaeoglobi	n.d.	n.d.
洛基古菌纲Lokiarchaeia	n.d.	n.d.
细菌Bacteria
α-变形菌纲α-Proteobacteria	13.837±3.349	10.524±2.115
酸微菌纲Acidimicrobiia	1.050±0.301*	1.397±0.184*
芽单胞菌纲Gemmatimonadetes	0.728±0.170	1.174±0.477
γ-变形菌纲γ-Proteobacteria	0.557±0.167*	0.906±0.335*
蓝藻纲Cyanophyceae	0.254±0.065	0.370±0.246
厌氧绳菌纲Anaerolineae	0.250±0.144	0.373±0.100
硝化螺旋菌纲Nitrospiria	0.165±0.104	0.270±0.096
绿弯菌纲Chloroflexi	0.080±0.028*	0.129±0.030*
迷踪菌纲Unclassified_Elusimicrobia	0.007±0.003	0.008±0.002
ζ-变形菌纲ζ-Proteobacteria	0.001±0.001	0.001±0.000
绿菌纲Chlorobiia	0.001±0.000	0.001±0.000
脱硫杆菌纲Desulfurobacteriia	n.d.	n.d.
弯曲杆菌纲Campylobacteria	n.d.	n.d.
热脱硫杆菌纲Thermodesulfovibrionia	n.d.	n.d.
δ-变形菌纲δ-Proteobacteria （SAR324）	n.d.	n.d.
放线菌纲Actinobacteria	n.d.	n.d.
螺旋体纲Leptospirae	n.d.	n.d.

固碳微生物分类（纲） Carbon-fixing microorganisms （class）	典型草原 Typical steppe	荒漠草原 Desert steppe
古细菌Archaea
亚硝化球菌纲Nitrososphaeria	0.389±0.203	0.571±0.284
热原体纲Thermoplasmata	0.003±0.000	0.003±0.001
深古菌纲Candidatus_Bathyarchaeota	0.003±0.002	0.003±0.001
热变形菌纲Thermoprotei	n.d.	n.d.
古丸菌纲Archaeoglobi	n.d.	n.d.
洛基古菌纲Lokiarchaeia	n.d.	n.d.
细菌Bacteria
α-变形菌纲α-Proteobacteria	13.837±3.349	10.524±2.115
酸微菌纲Acidimicrobiia	1.050±0.301*	1.397±0.184*
芽单胞菌纲Gemmatimonadetes	0.728±0.170	1.174±0.477
γ-变形菌纲γ-Proteobacteria	0.557±0.167*	0.906±0.335*
蓝藻纲Cyanophyceae	0.254±0.065	0.370±0.246
厌氧绳菌纲Anaerolineae	0.250±0.144	0.373±0.100
硝化螺旋菌纲Nitrospiria	0.165±0.104	0.270±0.096
绿弯菌纲Chloroflexi	0.080±0.028*	0.129±0.030*
迷踪菌纲Unclassified_Elusimicrobia	0.007±0.003	0.008±0.002
ζ-变形菌纲ζ-Proteobacteria	0.001±0.001	0.001±0.000
绿菌纲Chlorobiia	0.001±0.000	0.001±0.000
脱硫杆菌纲Desulfurobacteriia	n.d.	n.d.
弯曲杆菌纲Campylobacteria	n.d.	n.d.
热脱硫杆菌纲Thermodesulfovibrionia	n.d.	n.d.
δ-变形菌纲δ-Proteobacteria （SAR324）	n.d.	n.d.
放线菌纲Actinobacteria	n.d.	n.d.
螺旋体纲Leptospirae	n.d.	n.d.

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