A natural peatland microbial community studied in the DOE-supported SPRUCE whole-ecosystem warming experiment at the S1 Bog in northern Minnesota. The community inhabits acidic, carbon-rich, waterlogged peat and mediates terminal anaerobic carbon turnover, including acetoclastic and hydrogenotrophic methanogenesis. Metagenome-assembled genomes and metatranscriptomes show depth-stratified microbial composition, active methanogenesis by Candidatus Methanoflorens, and temperature-sensitive methane and carbon dioxide production driven by activity changes rather than wholesale community replacement.
Taxonomy
| Taxon | Ontology ID | Functional Roles | Abundance |
|---|---|---|---|
| methanogenic archaea at SPRUCE — ontology label: Archaea | NCBITaxon:2157 · TaxonMech · TraitMech |
SYNTROPHIC_PARTNER
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DOMINANT |
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| Acidobacteriota MAGs in SPRUCE peat — ontology label: Acidobacteriota | NCBITaxon:57723 · TaxonMech · TraitMech |
PRIMARY_DEGRADER
CROSS_FEEDER
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N/A |
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| deep peat acetogenic bacteria — ontology label: Bacteria | NCBITaxon:2 · TaxonMech · TraitMech |
SECONDARY_FERMENTER
CROSS_FEEDER
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N/A |
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Ecological Interactions
The graph shows only explicitly linked interaction participants. Community members without an asserted participant link are omitted; membership alone does not imply an interaction.
Soil Organic Matter-Derived Terminal Electron Acceptors
HYPOTHESIZED: multiomics and metabolite profiles suggest that cleavage of soil organic matter supplies terminal electron acceptors for anaerobic respiration. Relative gene abundances indicate substantial potential for sulfate/sulfite reduction, denitrification and acetogenesis; they do not directly rank process fluxes or demonstrate a neutral-beneficiary relationship between taxa. The authors explicitly require process-specific rate measurements to test the mechanism.
Metabolites: organic molecular entity (CHEBI:50860 · MediaIngredientMech · CMMMech), acetate (CHEBI:30089 · MediaIngredientMech · CMMMech)
Biological Processes:
- anaerobic respiration (GO:0009061 · PathwayMech)
HYPOTHESIZED: depth-dependent availability of electron acceptors released from organic matter may help select the metabolic pathways represented along the peat profile. The genomic and metabolite correlations support the conceptual model but do not independently isolate acceptor release as the cause of stratification.
Evidence
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PMID:40715043 - SUPPORT (COMPUTATIONAL)"Multi-omics data suggest that organic matter cleavage provides terminal electron acceptors, which together with methanogen metabolic flexibility, may explain peat microbiome composition resistance to warming."
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PMID:40715043 - SUPPORT (COMPUTATIONAL)"the predominant pathways for anaerobic carbon decomposition include sulfate/sulfite reduction, denitrification, and acetogenesis, rather than methanogenesis based on gene abundances"
Inferred Acetate Supply to Methanogens
CROSS_FEEDINGHYPOTHESIZED: acetogenic bacteria may supply acetate to methanogens, but the deep-peat guild-to-guild transfer is not directly traced. Greater deep-peat Wood-Ljungdahl pathway potential and acetate accumulation are distinct from surface acetogen activity associated with warming. Surface methanogens express acetoclastic and hydrogenotrophic pathways; acetate feeds the acetoclastic route, while hydrogenotrophy uses hydrogen and carbon dioxide. These observations do not demonstrate acetate transport from deep peat to the surface or quantify the contribution of this particular donor guild to warming-induced methane production.
Source Taxon: deep peat acetogenic bacteria
Target Taxon: methanogenic archaea at SPRUCE
Metabolites: acetate (CHEBI:30089 · MediaIngredientMech · CMMMech), methane (CHEBI:16183 · MediaIngredientMech · CMMMech), carbon dioxide (CHEBI:16526 · MediaIngredientMech · CMMMech)
Biological Processes:
- methane biosynthetic process (GO:0015948 · PathwayMech)
Evidence
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PMID:40715043 - SUPPORT (COMPUTATIONAL)"the mechanism by which elevated temperatures promote methanogenesis in the bog is through enhanced availability of substrates (e.g., acetate)."
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PMID:40715043 - SUPPORT (COMPUTATIONAL)"we find evidence that the dominant methanogen at SPRUCE, Ca. Methanoflorens, is actively performing both acetoclastic and hydrogenotrophic methanogenesis at the surface of the bog"
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PMID:40715043 - SUPPORT (COMPUTATIONAL)"the genomic potential for acetogenesis via the Wood-Ljungdahl pathway continues to increase, resulting in the highest concentrations of acetate in the deep peat"
Depth-Stratified Anaerobic Peat Metabolism
Community composition and genomic functional potential differ with peat depth. Surface layers contain more aerobic and fermentative potential, whereas deeper layers contain diverse anaerobic pathways and greater acetogenic potential. This supports environmental stratification, not by itself reduced competition among species or a measured flux from deep producers to surface consumers.
Metabolites: acetate (CHEBI:30089 · MediaIngredientMech · CMMMech)
Biological Processes:
- anaerobic respiration (GO:0009061 · PathwayMech)
- methane biosynthetic process (GO:0015948 · PathwayMech)
HYPOTHESIZED: the depth-associated distribution of acetogenic potential and acetate provides a possible substrate-supply context for methanogens in the peat. It does not establish a deep-to-surface transport pathway, a specific donor-recipient flux, or the cause of the surface warming response.
Evidence
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PMID:40715043 - SUPPORT (COMPUTATIONAL)"Depth was the main driver of variation in microbial community composition (P = 0.002, adjR2 = 0.13, Fig. 1A, B) and functional potential (P < 0.001, R2 = 0.623)."
Associated Datasets
| Dataset | Type | Repository | Accession |
|---|---|---|---|
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SPRUCE peat metagenomes
Public NCBI BioProject ranges containing raw metagenomic sequences from SPRUCE peat samples. |
METAGENOMICS | NCBI_BIOPROJECT | PRJNA364951-PRJNA364992; PRJNA443580-PRJNA443616; PRJNA444884-PRJNA444890; PRJNA651484-PRJNA651504; PRJNA677007-PRJNA677020; PRJNA697594-PRJNA697710 |
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SPRUCE MAG BioProject
NCBI BioProject containing metagenome-assembled genomes analyzed for the SPRUCE peat microbial community. |
GENOMICS | NCBI_BIOPROJECT | PRJNA1084886 |
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SPRUCE metaproteomics and metabolomics
Mass spectrometry proteomics datasets associated with the SPRUCE warming metagenome study. |
METAPROTEOMICS | MASSIVE | PXD063775; MSV000097832 |
Knowledge gaps & discussions (1)
KNOWLEDGE_GAP OPEN Which inferred electron-acceptor and acetate transfers are supported by direct process measurements?
The primary study explicitly presents a conceptual model and calls for process-specific rates and physiological confirmation. Preserve pathway potential, metabolite distributions and the observed surface expression response without equating them with quantified flux. Deep acetate accumulation does not identify its consumers or prove vertical transport. COMMUNITY_LEVEL stratification does not establish reduced competition. No new topology is introduced.
Attaches to: ecological_interactions#Soil Organic Matter-Derived Terminal Electron Acceptors, ecological_interactions#Inferred Acetate Supply to Methanogens, ecological_interactions#Depth-Stratified Anaerobic Peat Metabolism
1 evidence item(s)
our hypotheses must be confirmed by process-specific rate measurements in the future
The primary discussion explicitly limits mechanistic certainty.
Environmental Factors
| Factor | Value | Unit |
|---|---|---|
| Whole-ecosystem warming and elevated carbon dioxide | air and peat warming with elevated atmospheric CO2 | N/A |
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| Acidic organic-rich peat chemistry | pH 3.42 average outflow; total organic carbon 85.83 mg C/L | N/A |
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