A laboratory framework of 108 stable cyanobacteria-heterotroph consortia generated by coculturing five well-characterized model cyanobacterial strains with microorganisms filtered from three distinct freshwater sources. Metagenomic analysis across the 108 consortia identified a 25-species noncyanobacterial core microbiome that recurred independently of cyanobacterial host species or inoculum source, with statistically supported core functions in micronutrient biosynthesis, metabolite transport, and anoxygenic photosynthesis, and a significant enrichment of plasmids in core species suggesting plasmid-mediated symbiotic roles.
Taxonomy
| Taxon | Ontology ID | Functional Roles | Abundance |
|---|---|---|---|
| model cyanobacterial hosts — ontology label: Cyanobacteriota | NCBITaxon:1117 · TaxonMech · TraitMech |
PRIMARY_PRODUCER
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DOMINANT |
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| core noncyanobacterial heterotrophs — ontology label: Bacteria | NCBITaxon:2 · TaxonMech · TraitMech |
CROSS_FEEDER
SECONDARY_FERMENTER
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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.
Putative Plasmid Functions in the Cyanobacterial Core Microbiome
PARTIAL - Core microbiome MAGs are enriched in putative plasmid contigs carrying transport, carbohydrate-metabolism and signaling functions. Cobinning assigns plasmids to MAGs and 98% of predicted plasmids were not circularized. Their contribution to phototroph-heterotroph establishment or maintenance is HYPOTHESIZED from genomic content, not demonstrated plasmid transfer, curing, reciprocal fitness or metabolite flux.
Biological Processes:
- interspecies interaction between organisms (GO:0044419 · PathwayMech)
Evidence
-
PMID:40626910 - PARTIAL (IN_VITRO)"core species showed significant enrichment of plasmids, and functions encoded on plasmids suggested plasmid-mediated roles in symbiotic interactions"
Core Micronutrient and Anoxygenic Photosynthesis Functions
Core microbiome MAGs are statistically enriched in micronutrient biosynthesis, membrane transport and anoxygenic photosynthesis potential; 20 of 25 core MAGs encode anoxygenic photosystem components. These are genomic capabilities. Cross-feeding of costly cofactors or cyanobacterial products is HYPOTHESIZED, not measured expression, transferred metabolites or partner-specific growth benefit.
Biological Processes:
- vitamin biosynthetic process (GO:0009110 · PathwayMech)
- photosynthesis (GO:0015979 · PathwayMech)
- transmembrane transport (GO:0055085 · PathwayMech)
Evidence
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PMID:40626910 - SUPPORT (IN_VITRO)"core microbiome functionalities in micronutrient biosynthesis, metabolite transport, and anoxygenic photosynthesis"
Reproducible Core Recruitment Across Hosts and Inocula
Among 108 retained consortia, 25 species met an operational core definition: occurrence with at least four host strains and at least two source environments under replicated criteria. Individual core species occurred in 18.5%-68.5% of samples, not universally. Communities stabilized and showed broad convergence, while both host strain and inoculum significantly affected composition. Host-driven facilitation is PARTIAL because cyanobacteria-free controls were absent, leaving medium and laboratory selection unresolved.
Biological Processes:
- interspecies interaction between organisms (GO:0044419 · PathwayMech)
Evidence
-
PMID:40626910 - SUPPORT (IN_VITRO)"despite host and inoculum diversity, these consortia converged on a similar set of noncyanobacterial taxa"
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PMID:40626910 - SUPPORT (IN_VITRO)"Individual core species were present in 18.5%–68.5% of all samples"
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PMID:40626910 - PARTIAL (IN_VITRO)"The absence of cyanobacteria-free controls limited our ability to disentangle effects solely attributable to media or laboratory conditions."
Knowledge gaps & discussions (1)
KNOWLEDGE_GAP OPEN Which selective mechanisms explain the measured community responses?
The primary source establishes replicated enrichment, but host/source variation persists and the authors report no cyanobacteria-free controls. Bioinformatic removal of predicted plasmid contigs is an analytical comparison, not a biological plasmid intervention. Quantify selective host, plasmid and metabolite-exchange contributions before adding mechanistic arrows; statistical analysis enabled by recruitment is not a downstream ecological cause.
Attaches to: ecological_interactions#Putative Plasmid Functions in the Cyanobacterial Core Microbiome, ecological_interactions#Core Micronutrient and Anoxygenic Photosynthesis Functions, ecological_interactions#Reproducible Core Recruitment Across Hosts and Inocula
External Resources
| Name | Repository | Resource ID |
|---|---|---|
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Primary publication for the model cyanobacterial consortia framework
PubMed record for the Kust et al. 2025 ISME J paper characterizing a reproducible 25-species core microbiome across 108 cyanobacteria-heterotroph cocultures. |
OTHER | PMID:40626910 |
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DOI landing page
DOI link to the ISME J paper. |
OTHER | doi:10.1093/ismejo/wraf142 |
Environmental Factors
| Factor | Value | Unit |
|---|---|---|
| Freshwater inoculum diversity | three distinct freshwater sources | N/A |
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| Replicated coculture scale | 108 stable consortia | N/A |
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Growth Media
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