A grassland soil microbial community in which the structurally diverse corrinoid (vitamin B12-related) cofactor pool serves as a key determinant of community structure. Analysis of metagenome-assembled genomes implicates Thermoproteota, Actinobacteria, and Proteobacteria as the principal corrinoid suppliers. Corrinoids accumulate adhered to the soil matrix at levels exceeding the requirements of cultured bacteria. Enrichment cultures and soil microcosms seeded with different corrinoids exhibit distinct shifts in bacterial community composition, supporting the hypothesis that corrinoid structure shapes communities, with environmental context modulating both community-level and taxon-specific responses.
Taxonomy
| Taxon | Ontology ID | Functional Roles | Abundance |
|---|---|---|---|
| corrinoid-supplying Thermoproteota — ontology label: Thermoproteota | NCBITaxon:28889 · TaxonMech · TraitMech |
PRIMARY_PRODUCER
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N/A |
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| corrinoid-supplying Actinobacteria — ontology label: Actinomycetota | NCBITaxon:201174 · TaxonMech · TraitMech |
PRIMARY_PRODUCER
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N/A |
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| corrinoid-supplying Proteobacteria — ontology label: Pseudomonadota | NCBITaxon:1224 · TaxonMech · TraitMech |
PRIMARY_PRODUCER
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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.
Predicted Soil Corrinoid Supply Capacity
Metagenome-assembled genomes from Hopland grassland soil suggest that Thermoproteota, Actinobacteria and Proteobacteria contain the principal corrinoid-producing lineages. This is predicted capacity in a subset of genomes, not demonstrated production or exchange by every member of these phyla. HYPOTHESIZED: released corrinoids support dependent organisms directly or through a soil-associated reservoir; release and replenishment were not traced.
Participating Taxa: corrinoid-supplying Thermoproteota, corrinoid-supplying Actinobacteria, corrinoid-supplying Proteobacteria
Metabolites: corrinoid (CHEBI:33913 · MediaIngredientMech · CMMMech)
Biological Processes:
- cobalamin metabolic process (GO:0009235 · PathwayMech)
HYPOTHESIZED: the source model proposes that corrinoids released by predicted producers can adsorb to the soil matrix and contribute to its reservoir. The mechanism and magnitude of release and pool replenishment remain unknown; the MAG predictions do not trace this flux.
Evidence
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PMID:38832716 - PARTIAL (COMPUTATIONAL)"Analysis of metagenome-assembled genomes suggests that corrinoids are supplied to the community by members of the archaeal and bacterial phyla Thermoproteota, Actinobacteria, and Proteobacteria"
Corrinoid Amendment and Community Composition
Distinct corrinoid amendments altered bacterial composition in soil-derived enrichments and soil microcosms, with context-dependent responses. In soil microcosms, non-cobalamin treatments had stronger early effects than cobalamin, and the treatment effect was largely lost by the final sampling point. These amendment responses do not establish niche partitioning, a direct response by every taxon, or exposure to an equally diverse native reservoir.
Metabolites: corrinoid (CHEBI:33913 · MediaIngredientMech · CMMMech)
Biological Processes:
- cobalamin metabolic process (GO:0009235 · PathwayMech)
Evidence
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PMID:38832716 - SUPPORT (IN_VITRO)"Enrichment cultures and soil microcosms seeded with different corrinoids showed distinct shifts in bacterial community composition, supporting the hypothesis that corrinoid structure can shape communities."
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PMID:38832716 - SUPPORT (IN_VITRO)"Environmental context influenced both community- and taxon-specific responses to specific corrinoids."
Soil Corrinoid Reservoir and Hypothesized Buffering
Soil extraction and bioassays detected an abundant, strongly soil-associated corrinoid pool, expected to be predominantly cobalamin. The assay does not separate intracellular from extracellular corrinoids, and accessibility to resident microbes remains unclear. HYPOTHESIZED: this reservoir buffers community response to additional cobalamin; its role in stability was not isolated experimentally.
Metabolites: corrinoid (CHEBI:33913 · MediaIngredientMech · CMMMech)
Biological Processes:
- cobalamin metabolic process (GO:0009235 · PathwayMech)
HYPOTHESIZED: a predominantly cobalamin reservoir may buffer the community response to added cobalamin, helping explain the contrast with other corrinoid amendments and with soil-derived enrichments. This proposed modulation of the amendment response is not demonstrated release of a diverse native pool or proof that the reservoir caused the observed shifts.
Evidence
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PMID:38832716 - SUPPORT (IN_VITRO)"Corrinoids were found largely adhered to the soil matrix in a grassland soil, at levels exceeding those required by cultured bacteria."
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PMID:38832716 - PARTIAL (OTHER)"These results implicate corrinoids as key determinants of soil microbiome structure and suggest that environmental micronutrient reservoirs promote community stability."
Knowledge gaps & discussions (1)
KNOWLEDGE_GAP OPEN How much of the measured corrinoid pool is accessible to resident microbes, and does it mediate the community response to amendment?
The primary results and discussion distinguish total corrinoid measurement, genome-based producer inference and two proposed cycling routes. Intracellular/extracellular partitioning, producer release and accessibility are unresolved. Both original directions are retained only as explicitly HYPOTHESIZED links in the authors' model. No new donor-recipient mechanism or direction is added. Taxonomic role/evidence overclaims outside the graph remain tracked in issue #1814.
Attaches to: ecological_interactions#Predicted Soil Corrinoid Supply Capacity, ecological_interactions#Corrinoid Amendment and Community Composition, ecological_interactions#Soil Corrinoid Reservoir and Hypothesized Buffering
1 evidence item(s)
These results implicate corrinoids as key determinants of soil microbiome structure and suggest that environmental micronutrient reservoirs promote community stability.
The source says suggest: reservoir-mediated stability remains an interpretation.
External Resources
| Name | Repository | Resource ID |
|---|---|---|
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Primary publication for the soil corrinoid reservoir community
PubMed record for the Hallberg et al. 2024 ISME J paper on soil microbial community response to corrinoids. |
OTHER | PMID:38832716 |
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DOI landing page
DOI link to the ISME J paper. |
OTHER | doi:10.1093/ismejo/wrae094 |
Environmental Factors
| Factor | Value | Unit |
|---|---|---|
| Corrinoid amendment | enrichments seeded with different corrinoid structures | N/A |
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