A unialgal xenic freshwater cyanobacterial culture centered on Dolichospermum flosaquae FBCC-A233 and two co-maintained alphaproteobacterial associates assigned to Sphingorhabdus sp. and Brevundimonas sp. Kim et al. reconstructed complete circular genomes from the FBCC-A233 culture, resolved the associated bacterial genomes at genus level, and predicted an asymmetric cofactor economy in which D. flosaquae FBCC-A233 encoded BioU-mediated de novo biotin and extensive anaerobic corrinoid biosynthesis potential while the associated bacteria lacked complete de novo biotin and cobamide biosynthetic pathways.
Taxonomy
| Taxon | Ontology ID | Functional Roles | Abundance |
|---|---|---|---|
| Dolichospermum flosaquae FBCC-A233 — ontology label: Dolichospermum flos-aquae | NCBITaxon:1166 · TaxonMech · TraitMech |
PRIMARY_PRODUCER
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DOMINANT |
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| Sphingorhabdus sp. FBCC-A233 associate — ontology label: Sphingorhabdus | NCBITaxon:1434046 · TaxonMech · TraitMech | RARE | |
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| Brevundimonas sp. FBCC-A233 associate — ontology label: Brevundimonas | NCBITaxon:41275 · TaxonMech · TraitMech | RARE | |
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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.
Genome-inferred biotin asymmetry
D. flosaquae FBCC-A233 was the only recovered genome with a complete BioU-mediated de novo biotin-biosynthesis route, whereas Sphingorhabdus sp. and Brevundimonas sp. lacked complete de novo pathways while retaining biotin-dependent carboxylase genes. These are genomic potentials in three recovered genomes, not measured production, transfer or growth dependence, and not a complete culture census.
Participating Taxa: Dolichospermum flosaquae FBCC-A233, Sphingorhabdus sp. FBCC-A233 associate, Brevundimonas sp. FBCC-A233 associate
Metabolites: biotin (CHEBI:15956 · MediaIngredientMech · CMMMech)
Biological Processes:
- vitamin biosynthetic process (GO:0009110 · PathwayMech)
Evidence
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PMID:42535840 - PARTIAL (COMPUTATIONAL)"D. flosaquae FBCC-A233 was the only genome encoding the BioU-mediated de novo biotin biosynthesis route"
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PMID:42535840 - PARTIAL (COMPUTATIONAL)"associated bacterial genomes lacked complete de novo biosynthetic pathways"
Genome-inferred corrinoid utilization asymmetry
D. flosaquae FBCC-A233 encoded most anaerobic corrinoid-ring biosynthesis genes, while Sphingorhabdus sp. and Brevundimonas sp. lacked complete de novo cobamide biosynthesis and retained different methionine-synthase repertoires. A ring-pathway step and the canonical DMB lower-ligand branch remain unresolved; neither canonical cobalamin identity nor cofactor exchange is established. Transport and methionine uptake alternatives do not demonstrate cobamide import.
Participating Taxa: Dolichospermum flosaquae FBCC-A233, Sphingorhabdus sp. FBCC-A233 associate, Brevundimonas sp. FBCC-A233 associate
Evidence
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PMID:42535840 - PARTIAL (COMPUTATIONAL)"D. flosaquae FBCC-A233 encoded most genes required for anaerobic corrinoid-ring biosynthesis"
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PMID:42535840 - PARTIAL (COMPUTATIONAL)"The associated bacterial genomes lacked complete de novo cobamide biosynthesis but retained cobamide-related utilization genes"
Knowledge gaps & discussions (1)
KNOWLEDGE_GAP OPEN Test whether D. flosaquae FBCC-A233 releases biotin or cobamides that are used by the Sphingorhabdus and Brevundimonas associates.
The publication infers cofactor asymmetry from complete genomes but explicitly reports that biotin and cobamide uptake, export, identity, and growth-dependence mechanisms remain unresolved. No causal arrow connects these parallel predictions. Cofactor chemistry, export, uptake and growth-rescue experiments are needed before assigning cross-feeding. Recovered genomes do not exhaust the xenic culture; abundance and stability metadata remain separate under #1406.
Attaches to: ecological_interactions#Genome-inferred biotin asymmetry, ecological_interactions#Genome-inferred corrinoid utilization asymmetry
1 evidence item(s)
These profiles do not demonstrate cobamide cross-feeding
The authors explicitly warn that the genome profiles nominate candidate interactions rather than directly demonstrating metabolite exchange.
External Resources
| Name | Repository | Resource ID |
|---|---|---|
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Primary publication - Dolichospermum FBCC-A233 xenic culture
PubMed record for the Microbiology Spectrum genome-resolved study of D. flosaquae FBCC-A233 and its two associated alphaproteobacterial genomes. |
OTHER | PMID:42535840 |
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Publication DOI - Dolichospermum FBCC-A233 xenic culture
DOI for the Microbiology Spectrum study of the genome-resolved FBCC-A233 xenic culture. |
OTHER | 10.1128/spectrum.01014-26 |
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BioProject PRJNA1404972
NCBI BioProject carrying the raw sequencing reads and genome assemblies for the recovered D. flosaquae FBCC-A233, Sphingorhabdus sp., and Brevundimonas sp. genomes. |
OTHER | PRJNA1404972 |
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Environmental Factors
| Factor | Value | Unit |
|---|---|---|
| Original freshwater reservoir source | Inpyeong Reservoir, Taean-gun, Republic of Korea | N/A |
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| Serial single-filament maintenance | approximately 10-day intervals | N/A |
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Growth Media
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