A two-member vitamin cross-feeding microcosm derived from mine tailings laboratory microbial consortia, in which a Variovorax species produces thiamine (vitamin B1) as a community hub for correlated thiamine auxotrophs and a Cryptococcus yeast supplies pantothenate (vitamin B5) required by Variovorax. Co-culture of the two members yielded a 90-130 fold fitness increase for both organisms, supporting the bidirectional vitamin-dependent mutualism predicted from metagenome-informed abundance correlation networks of mine-tailings-derived consortia grown under dozens of conditions.
Taxonomy
| Taxon | Ontology ID | Functional Roles | Abundance |
|---|---|---|---|
| Variovorax species — ontology label: Variovorax | NCBITaxon:34072 · TaxonMech · TraitMech |
CROSS_FEEDER
PRIMARY_PRODUCER
|
N/A |
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| Cryptococcus yeast — ontology label: Cryptococcus <basidiomycete fungi> | NCBITaxon:5206 · TaxonMech · TraitMech |
CROSS_FEEDER
PRIMARY_PRODUCER
|
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.
Variovorax thiamine provision to Cryptococcus
CROSS_FEEDINGThe isolated Variovorax produces extracellular thiamine, and the tested Cryptococcus grows better with thiamine supplementation and in coculture. Together these experiments support thiamine cross-feeding to this yeast. They do not validate every correlated auxotroph as a recipient. Cryptococcus was not included in the correlation network. The up-to-100 mg/L measurement belongs to a separate spent-medium-supplemented assay, not a measured concentration in the two-member coculture.
Source Taxon: Variovorax species
Target Taxon: Cryptococcus yeast
Metabolites: thiamine (CHEBI:18385 · MediaIngredientMech · CMMMech)
Biological Processes:
- thiamine biosynthetic process (GO:0009228 · PathwayMech)
- interspecies interaction between organisms (GO:0044419 · PathwayMech)
Thiamine production and yeast thiamine responsiveness support one resource route contributing to the observed coculture benefit. This does not establish all correlated recipients or vitamin exchange as the only cause of that benefit.
Evidence
-
PMID:37553333 - SUPPORT (IN_VITRO)"Quantification of thiamine during the growth of Variovorax in minimal media show high levels of thiamine production"
Cryptococcus Pantothenate Provision to Variovorax
CROSS_FEEDINGCryptococcus spent medium contains pantothenate, Variovorax requires pantothenate for substantial growth, and supplementation supports its growth. These controls and coculture benefit support reciprocal vitamin provisioning. They do not isolate pantothenate as the sole growth-promoting component of spent medium or resolve every in-coculture flux.
Source Taxon: Cryptococcus yeast
Target Taxon: Variovorax species
Metabolites: pantothenate (CHEBI:7916 · MediaIngredientMech · CMMMech)
Biological Processes:
- pantothenate biosynthetic process (GO:0015940 · PathwayMech)
- interspecies interaction between organisms (GO:0044419 · PathwayMech)
Yeast pantothenate production and bacterial supplementation response support the reciprocal resource route contributing to coculture benefit. The controls do not exclude other spent-medium components or establish exclusive mediation.
Evidence
-
PMID:37553333 - SUPPORT (IN_VITRO)"A Cryptococcus yeast produces the B-vitamin pantothenate"
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PMID:37553333 - SUPPORT (IN_VITRO)"pantothenate, which we show is required for growth of Variovorax"
Bidirectional Vitamin Mutualism in Coculture
MUTUALISMBoth isolates achieve higher viable cell densities in coculture than in monoculture over the reported serial-passage assay, supporting MUTUALISM under those conditions. Auxotrophy, supplementation and extracellular vitamin measurements support a vitamin-exchange mechanism, without proving vitamin-only mediation or direct interaction in the original mixed bioreactors. Quantitative fold-change statements differ within the paper, so no reconciled fold increase is assigned here.
Source Taxon: Variovorax species
Target Taxon: Cryptococcus yeast
Metabolites: thiamine (CHEBI:18385 · MediaIngredientMech · CMMMech), pantothenate (CHEBI:7916 · MediaIngredientMech · CMMMech)
Biological Processes:
- interspecies interaction between organisms (GO:0044419 · PathwayMech)
Evidence
-
PMID:37553333 - SUPPORT (IN_VITRO)"co-culturing with Variovorax leads to a 90-130-fold fitness increase for both organisms"
Knowledge gaps & discussions (1)
KNOWLEDGE_GAP OPEN How much of the coculture benefit is mediated by each vitamin, and which quantitative values are reconciled?
The abstract/discussion report 90-130-fold increases; the Fig.6 caption gives about 50-fold for yeast, while the bacterial Results densities imply a different ratio. Results describe Cryptococcus monoculture spent medium, whereas Methods describe final-passage coculture spent medium for quantification. No corrected value or uniquely resolved medium source is invented. Raw data and supplementary files were not audited. The controls support vitamin-dependent mutualism without establishing vitamin-only mediation or native bioreactor pairing. Supplementation/network metadata remains issue #1912.
Attaches to: ecological_interactions#Variovorax thiamine provision to Cryptococcus, ecological_interactions#Cryptococcus Pantothenate Provision to Variovorax, ecological_interactions#Bidirectional Vitamin Mutualism in Coculture
1 evidence item(s)
co-culturing with Variovorax leads to a 90-130-fold fitness increase for both organisms
The abstract supports positive effects on both partners. Its 90-130-fold figure differs from the Fig.6 caption and from the ratio implied by the Results bacterial densities; retain qualitative benefit, not a corrected numerical claim.
External Resources
| Name | Repository | Resource ID |
|---|---|---|
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Primary publication for the vitamin-interdependency microcosm
PubMed record for the Hessler et al. 2023 Nature Communications paper validating predicted vitamin cross-feeding in mine-tailings-derived microcosms. |
OTHER | PMID:37553333 |
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DOI landing page
DOI link to the Nature Communications paper. |
OTHER | doi:10.1038/s41467-023-40360-4 |
Environmental Factors
| Factor | Value | Unit |
|---|---|---|
| Minimal vitamin-defined media | minimal medium with controlled vitamin availability | N/A |
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Growth Media
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