A defined marine algal-bacterial coculture in which the picoeukaryotic alga Ostreococcus tauri OTH95 and the roseobacter Dinoroseobacter shibae DF-12 form a reciprocal B-vitamin mutualism. D. shibae supplies cobalamin and thiamine needed by O. tauri, while O. tauri satisfies bacterial requirements for other B vitamins in a stable long-term coculture; the interaction is experimentally tractable under controlled light, temperature, and vitamin-amendment regimes.
Taxonomy
| Taxon | Ontology ID | Functional Roles | Abundance |
|---|---|---|---|
| Ostreococcus tauri | NCBITaxon:70448 · TaxonMech · TraitMech |
PRIMARY_PRODUCER
CROSS_FEEDER
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COMMON |
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| Dinoroseobacter shibae | NCBITaxon:215813 · TaxonMech · TraitMech |
CROSS_FEEDER
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COMMON |
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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.
Bacterial Rescue of Algal Cobalamin and Thiamine Auxotrophy
MUTUALISMD. shibae significantly rescues O. tauri growth under cobalamin or thiamine omission compared with corresponding axenic cultures. Rescue of the B12 requirement is stronger: without thiamine, algal carrying capacity in coculture was only about 30% of the vitamin-supplemented condition. This is demonstrated physiological complementation, not a measurement of secreted vitamin flux or a complete rescue of every vitamin requirement.
Source Taxon: Dinoroseobacter shibae
Target Taxon: Ostreococcus tauri
Metabolites: cobalamin (CHEBI:30411 · MediaIngredientMech · CMMMech), thiamine (CHEBI:18385 · MediaIngredientMech · CMMMech)
Biological Processes:
- vitamin biosynthetic process (GO:0009110 · PathwayMech)
- biological process involved in interspecies interaction between organisms (GO:0044419 · PathwayMech)
Bacterial complementation of algal vitamin requirements sustains the algal partner under the tested vitamin-omission conditions and contributes to serial coculture persistence. This positive physiological dependence does not isolate a transporter, secretion mechanism or the cause of the near 1:1 population ratio.
Evidence
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PMID:30228381 - SUPPORT (IN_VITRO)"B12 and B1 auxotrophy of O. tauri can be alleviated by co-culturing with a heterotrophic bacterial partner Dinoroseobacter shibae"
Algal Rescue of Bacterial Vitamin Requirements
MUTUALISMO. tauri significantly complements D. shibae requirements for niacin, biotin and p-aminobenzoic acid compared with the corresponding vitamin-deficient monocultures. This reciprocal physiological rescue supports mutualism, not merely one-way commensalism. The exact transport/release routes were not investigated; the ratio-dynamics experiment supplied thiamine and biotin to shorten growth times, unlike the all-vitamin-omission assay.
Source Taxon: Ostreococcus tauri
Target Taxon: Dinoroseobacter shibae
Metabolites: biotin (CHEBI:15956 · MediaIngredientMech · CMMMech)
Biological Processes:
- vitamin biosynthetic process (GO:0009110 · PathwayMech)
- biological process involved in interspecies interaction between organisms (GO:0044419 · PathwayMech)
Evidence
-
PMID:30228381 - SUPPORT (IN_VITRO)"alga is in turn able to satisfy the reciprocal vitamin requirements of its bacterial partner in a stable long-term co-culture"
Stable B-Vitamin Mutualism Maintains Coculture
MUTUALISMBoth partners persisted through serial subcultures under mutually dependent nutrient conditions. Initial-ratio experiments reached approximately 1:1, and serial persistence was reported over four consecutive subcultures. Thiamine and biotin were supplied in the ratio-dynamics experiment, whereas separate omission assays tested all five vitamins. Vitamin/carbon addback changed the ratio; this supports nutrient dependence but not exclusive active population regulation, because competition for other nutrients remains possible.
Participating Taxa: Ostreococcus tauri, Dinoroseobacter shibae
Biological Processes:
- photosynthesis (GO:0015979 · PathwayMech)
- biological process involved in interspecies interaction between organisms (GO:0044419 · PathwayMech)
Evidence
-
PMID:30228381 - SUPPORT (IN_VITRO)"O. tauri and D. shibae continued to grow in a stable self-sustaining mutualistic"
Associated Datasets
| Dataset | Type | Repository | Accession |
|---|---|---|---|
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Ostreococcus-Dinoroseobacter B-vitamin rescue phenotyping
Primary study reporting growth assays, repeated subculture phenotypes, and genomic pathway analysis for O. tauri OTH95 and D. shibae DF-12. |
PHENOTYPE | OTHER | PMID:30228381 |
Knowledge gaps & discussions (1)
KNOWLEDGE_GAP OPEN How should reciprocal vitamin rescue be connected to persistence without equating it with a resolved population-regulation mechanism?
The demonstrated algal-to-bacterial rescue merits a separate rescue-to-persistence arrow, pending scoped Edison/report review. The removed reverse arrow described fixed carbon but targeted vitamin rescue. No passive-versus-active release mechanism was tested, and other nutrient competition was not excluded. One 9032 character Edison dry run is not a provider report or authorization to spend.
Attaches to: ecological_interactions#Bacterial Rescue of Algal Cobalamin and Thiamine Auxotrophy, ecological_interactions#Algal Rescue of Bacterial Vitamin Requirements, ecological_interactions#Stable B-Vitamin Mutualism Maintains Coculture
1 evidence item(s)
alga is in turn able to satisfy the reciprocal vitamin requirements of its bacterial partner in a stable long-term co-culture
Supports reciprocal vitamin provisioning from O. tauri to D. shibae.
Environmental Factors
| Factor | Value | Unit |
|---|---|---|
| B-vitamin availability | cobalamin, thiamine, biotin, niacin, and p-aminobenzoic acid amendments varied experimentally | N/A |
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| light-dark cycle | 16:8 h light:dark at 18 C | N/A |
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Growth Media
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