A synthetic, light-driven consortium pairing the cyanobacterium Synechococcus elongatus PCC 7942 (engineered to secrete sucrose via the cscB+ transporter) with Bacillus subtilis 168. The cyanobacterium fixes CO2 and exports sucrose, which supports heterotrophic growth of B. subtilis. This modular platform demonstrates a stable photosynthetic co-culture for sustainable carbon cycling.
Taxonomy
| Taxon | Ontology ID | Functional Roles | Abundance |
|---|---|---|---|
| Synechococcus elongatus PCC 7942 cscB+ — ontology label: Synechococcus elongatus | NCBITaxon:32046 · TaxonMech · TraitMech |
PRIMARY_PRODUCER
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DOMINANT |
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| Bacillus subtilis 168 — ontology label: Bacillus subtilis | NCBITaxon:1423 · TaxonMech · TraitMech |
CROSS_FEEDER
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ABUNDANT |
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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.
CO2 Fixation and Sucrose Production
CROSS_FEEDINGEngineered cscB+ S. elongatus provides photosynthetic carbon, including exported sucrose, to Bacillus-containing cocultures. This record names B. subtilis 168, used in the alpha-amylase demonstration; several growth and perturbation experiments instead used 3610. Preserve carbon support without transferring all 3610 results to strain 168.
Source Taxon: Synechococcus elongatus PCC 7942 cscB+
Target Taxon: Bacillus subtilis 168
Metabolites: sucrose (CHEBI:17992 · MediaIngredientMech · CMMMech)
Biological Processes:
- photosynthesis (GO:0015979 · PathwayMech)
- sucrose biosynthetic process (GO:0005986 · PathwayMech)
PARTIAL: cyanobacterial sucrose export is the proposed carbon supply for the existing heterotrophic-growth node. Sucrose-dependent Bacillus growth and the 168-specific production assay support this route, but exact growth kinetics must remain strain-specific.
Evidence
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PMID:28127397 - SUPPORT (IN_VITRO)"We previously engineered a model cyanobacterium, Synechococcus elongatus PCC 7942, to secrete the bulk of the carbon it fixes as sucrose, a carbohydrate that can be utilized by many other microbes"
Sucrose Uptake and Heterotrophic Growth
PARTIAL: photosynthate supported Bacillus cocultures, with initial growth followed by declining viability in batch assays. B. subtilis 168 was explicitly used for active alpha-amylase production, which increased with induced cyanobacterial sucrose secretion. That positive result does not establish weeks-to-months persistence of strain 168 or justify assigning 3610 perturbation results to it.
Participating Taxa: Bacillus subtilis 168
Metabolites: sucrose (CHEBI:17992 · MediaIngredientMech · CMMMech)
Biological Processes:
- sucrose catabolic process (GO:0005987 · PathwayMech)
Evidence
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PMID:28127397 - PARTIAL (IN_VITRO)"We observed heterotrophic growth dependent upon cyanobacterial photosynthate in each co-culture pair"
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PMID:28127397 - PARTIAL (IN_VITRO)"In consortia with S. elongatus, B. subtilis 168 produces alpha-amylase after 24 hours in constant light"
Knowledge gaps & discussions (1)
KNOWLEDGE_GAP OPEN Which strain- and condition-specific interactions explain growth and persistence in this dyad?
The source combines batch, continuous, density-dependent and production assays. Keep their positive results without treating every partner or strain as persistent for weeks to months. Cyanobacterial growth stimulation is observed, but metabolite return and byproduct absorption remain hypotheses. Light-associated inhibition is supported without identifying oxygen as the exclusive cause. For Bacillus, the canonical168 production assay is distinct from 3610 perturbation experiments. For E. coli, the early non-sucrose inference differs from later sucrose-sensitive production; for yeast, W303Clump is not parental W303. No new causal node, direction, cultivation protocol or strain optimization is added.
Attaches to: ecological_interactions#CO2 Fixation and Sucrose Production, ecological_interactions#Sucrose Uptake and Heterotrophic Growth
1 evidence item(s)
we hypothesize that these benefits arise from emergent cross-feeding of metabolite(s) and/or absorption of byproducts
Source-explicit proposed mediator of cyanobacterial stimulation, not a measured transfer mechanism.
Growth Media
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