A marine cyanobacterial colony consortium centered on the nitrogen-fixing photoautotroph Trichodesmium erythraeum IMS101 and conserved heterotrophic partners, especially Alteromonas macleodii. Multi-omics studies support recurring Trichodesmium-associated bacterial consortia in cultures and natural colonies, with potential interactions involving iron and phosphorus acquisition, vitamin B12 exchange, small-carbon compound catabolism, reactive oxygen detoxification, and coordinated diel resource cycling.
Taxonomy
| Taxon | Ontology ID | Functional Roles | Abundance |
|---|---|---|---|
| Trichodesmium erythraeum IMS101 | NCBITaxon:203124 · TaxonMech · TraitMech |
PRIMARY_PRODUCER
|
N/A |
|
|||
| Alteromonas macleodii Trichodesmium associate — ontology label: Alteromonas macleodii | NCBITaxon:28108 · TaxonMech · TraitMech |
CROSS_FEEDER
SECONDARY_FERMENTER
|
N/A |
|
|||
| Trichodesmium-associated heterotrophic microbiome — ontology label: Bacteria | NCBITaxon:2 · TaxonMech · TraitMech |
CROSS_FEEDER
|
N/A |
|
|||
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.
Colony Substrate Colonization by Heterotrophs
Trichodesmium colonies provide physical and nutrient-rich habitats associated with heterotrophs. The 2017 study recovered an A. macleodii representative genome from an IMS101 laboratory enrichment and found a conserved association across culture and environmental samples. This establishes association, not commensal neutrality, universal mutualism or a causal explanation of the separate 2018 field day-night transcript patterns. Named participants here identify the laboratory association, not an assertion that the field host was the IMS101 strain.
Participating Taxa: Trichodesmium erythraeum IMS101, Alteromonas macleodii Trichodesmium associate
Biological Processes:
- nitrogen fixation (GO:0009399 · PathwayMech)
Evidence
-
PMID:28440800 - SUPPORT (COMPUTATIONAL)"macroscopic colonies that serve as relatively nutrient-rich substrates"
Putative Alteromonas Helper Functions in Trichodesmium Colonies
HYPOTHESIZED: comparative genomics and transcription identify candidate A. macleodii contributions to Trichodesmium nutrient acquisition, small-carbon recycling and ROS detoxification. The study also assayed siderophore production in isolates and reported Trichodesmium DMSP production; those measurements do not establish complete interpartner fluxes or reciprocal fitness effects. The proposed B12 direction is host-to-epibiont, not Alteromonas-to-Trichodesmium, and the 2017 genome permits facultative B12 use. These candidates are not demonstrated causes of the later field co-expression phenotype.
Source Taxon: Alteromonas macleodii Trichodesmium associate
Target Taxon: Trichodesmium erythraeum IMS101
Metabolites: phosphate (CHEBI:18367 · MediaIngredientMech · CMMMech), iron(2+) (CHEBI:29033 · MediaIngredientMech · CMMMech), vitamin B12 (CHEBI:176843 · MediaIngredientMech · CMMMech), reactive oxygen species (CHEBI:26523 · MediaIngredientMech · CMMMech)
Biological Processes:
- reactive oxygen species detoxification (GO:0098869 · PathwayMech)
Evidence
-
PMID:28440800 - PARTIAL (COMPUTATIONAL)"iron and phosphorus acquisition, vitamin B12 exchange"
-
PMID:28440800 - PARTIAL (COMPUTATIONAL)"detoxification of reactive oxygen species"
Field Host-Microbiome Diel Coexpression
Sixteen field-colony metatranscriptomes over three day-night transitions in the North Pacific Subtropical Gyre showed coordinated host/microbiome expression, including nitrogen-, carbon-, iron- and B12-related functions. This is coexpression supporting candidate resource interactions, not directly demonstrated cross-feeding, a metabolite flux, or causation by A. macleodii helper genes. The host was field Trichodesmium, not demonstrated to be IMS101; Alteromonas genus transcripts must not be assigned wholesale to A. macleodii. The participant list credits only the record microbiome guild that this field measurement supports. Pseudocobalamin/DMB remodeling and host-to-microbiome provision remain interpretations.
Participating Taxa: Trichodesmium-associated heterotrophic microbiome
Biological Processes:
- photosynthesis (GO:0015979 · PathwayMech)
- nitrogen fixation (GO:0009399 · PathwayMech)
Evidence
-
PMID:29382945 - SUPPORT (COMPUTATIONAL)"significantly coordinated patterns of gene expression between host and microbiome"
-
PMID:29382945 - SUPPORT (COMPUTATIONAL)"linked to key resources including nitrogen, carbon, and iron"
Associated Datasets
| Dataset | Type | Repository | Accession |
|---|---|---|---|
|
Trichodesmium consortium metatranscriptomes
Publication reporting metatranscriptome sequencing of Trichodesmium colonies from the North Pacific Subtropical Gyre. |
METATRANSCRIPTOMICS | OTHER | PMID:29382945 |
Knowledge gaps & discussions (1)
KNOWLEDGE_GAP OPEN Which candidate helper activities mediate resource flux or host benefit in the exact association?
Genomic complementation and field coexpression generate testable hypotheses, not selective mediation or reciprocal-fitness measurements. The removed arrows described habitat context and cross-study candidate explanations. Host-to-microbiome B12 provision, pseudocobalamin remodeling and possible DMB supply are unresolved mechanistic interpretations. Exact laboratory strain, isolate source and field-community identities must remain distinct; non-graph reconciliation is #1886. Existing #297 ROS compound/process and #765 publication-body provenance decisions are preserved.
Attaches to: ecological_interactions#Colony Substrate Colonization by Heterotrophs, ecological_interactions#Putative Alteromonas Helper Functions in Trichodesmium Colonies, ecological_interactions#Field Host-Microbiome Diel Coexpression
1 evidence item(s)
Evidence of microbiome reliance on Trichodesmium-derived vitamin B12
The abstract gives the proposed host-to-microbiome direction as an inference from coexpression, not a traced flux.
Environmental Factors
| Factor | Value | Unit |
|---|---|---|
| oligotrophic warm ocean habitat | warm oligotrophic oceans | N/A |
|
||
| day-night cycle | diel cycle | N/A |
|
||
Growth Media
Cross-Mech Suite Links
Explore related entities across the CultureBotAI X-Mech knowledge bases: