A synthetic, light-driven two-species coculture pairing engineered Synechococcus elongatus PCC 7942 cscB with engineered Pseudomonas putida strains that consume cyanobacterial sucrose. The cyanobacterium fixes CO2 and exports sucrose under salt/IPTG induction, while P. putida converts the transferred carbon into polyhydroxyalkanoates (PHA) and, in a related engineered implementation, transforms the industrial pollutant 2,4-dinitrotoluene. This platform is relevant to DOE carbon utilization, bioproduct formation, and contaminant bioremediation because it couples photosynthetic CO2 fixation to heterotrophic biocatalysis in a controlled laboratory community.
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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| Pseudomonas putida engineered sucrose-utilizing partner — ontology label: Pseudomonas putida | NCBITaxon:303 · TaxonMech · TraitMech |
CROSS_FEEDER
PRIMARY_DEGRADER
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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.
Photosynthetic Sucrose Cross-Feeding
CROSS_FEEDINGS. elongatus cscB supplies photosynthetically derived sucrose to engineered P. putida partners. This record spans distinct implementations: cscAB PHA production, cscRABY and its nitrate-blind derivative, and EM173-derived DNT transformation. Their outcomes and growth-feedback assays are not interchangeable strain-level observations.
Source Taxon: Synechococcus elongatus PCC 7942 cscB
Target Taxon: Pseudomonas putida engineered sucrose-utilizing partner
Metabolites: carbon dioxide (CHEBI:16526 · MediaIngredientMech · CMMMech), sucrose (CHEBI:17992 · MediaIngredientMech · CMMMech)
Biological Processes:
- photosynthesis (GO:0015979 · PathwayMech)
- sucrose biosynthetic process (GO:0005986 · PathwayMech)
Cyanobacterial sucrose supplies carbon for P. putida PHA accumulation in the production assays. Polymer accumulation depends on the tested strain and nitrogen regime; the nitrate-blind comparison measures final accumulation, not a production-rate increase.
In the separate EM173-derived DNT implementation, sucrose from encapsulated cyanobacteria supports heterotrophic growth and metabolism during DNT biotransformation. This does not equate pollutant disappearance with complete mineralization.
Evidence
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PMID:28814973 - SUPPORT (IN_VITRO)"this sugar serves as C-source for Pseudomonas putida cscAB"
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PMID:32064751 - SUPPORT (IN_VITRO)"cyanobacteria fix CO2 through photosynthetic metabolism and secrete sufficient carbohydrates"
Heterotrophic PHA Accumulation
P. putida cscAB accumulated medium-chain-length PHA from cyanobacterial sucrose, with 3-hydroxydecanoate the most abundant monomer. A separate cscRABY nitrate-blind study reported an 8.8-fold increase in final PHA accumulation relative to its nitrate-consuming reference, not a measured rate increase. These production phenotypes are not additional cross-feeding events and do not establish PHB homopolymer identity.
Participating Taxa: Synechococcus elongatus PCC 7942 cscB, Pseudomonas putida engineered sucrose-utilizing partner
Metabolites: sucrose (CHEBI:17992 · MediaIngredientMech · CMMMech), polyhydroxyalkanoate (CHEBI:78037 · MediaIngredientMech · CMMMech)
Biological Processes:
- sucrose catabolic process (GO:0005987 · PathwayMech)
Evidence
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PMID:28814973 - SUPPORT (IN_VITRO)"with 3-hydroxydecanoic acid being the most abundant monomer"
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PMID:32523942 - SUPPORT (IN_VITRO)"these numbers are based on the snapshot at the end of the experiment"
DNT Biotransformation with Photosynthetic Carbon Input
The EM173-derived P. putida EM.DNT.S partner transformed 2,4-DNT in coculture with alginate-encapsulated S. elongatus CscB. Oxidative-intermediate measurements support pathway activity, whereas disappearance from solution also includes adsorption and reductive transformation. Complete mineralization was not directly established; the paper gives a model-based estimate. The same implementation accumulated PHA under nitrogen depletion, without proving a PHB homopolymer composition.
Participating Taxa: Synechococcus elongatus PCC 7942 cscB, Pseudomonas putida engineered sucrose-utilizing partner
Metabolites: 2,4-dinitrotoluene (CHEBI:920 · MediaIngredientMech · CMMMech), sucrose (CHEBI:17992 · MediaIngredientMech · CMMMech)
Biological Processes:
- xenobiotic metabolic process (GO:0006805 · PathwayMech)
Evidence
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PMID:32064751 - SUPPORT (IN_VITRO)"a portion of 2,4-DNT is also transformed via reductive processes"
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PMID:32064751 - SUPPORT (IN_VITRO)"we could not precisely quantitate the flux through the oxidative pathway with our data"
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PMID:32064751 - SUPPORT (IN_VITRO)"Both engineered P. putida strains were able to accumulate the polymer under nitrogen-limited conditions"
Growth-Promoting Partner Feedback
MUTUALISMIn the cscRABY study, P. putida promoted cyanobacterial growth and prevented photobleaching in tested contexts while receiving photosynthetic carbon. MUTUALISM here denotes that conditional carbon-supported partnership, not a universal fitness response: P. putida growth was not improved relative to matched external-sucrose controls. PARTIAL: additional molecular exchange and the mechanism of growth promotion remain hypotheses; mixed-cell omics and transporter regulation do not identify a transferred mediator. Sucrose is not a reverse donation.
Source Taxon: Pseudomonas putida engineered sucrose-utilizing partner
Target Taxon: Synechococcus elongatus PCC 7942 cscB
Evidence
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PMID:38609451 - SUPPORT (IN_VITRO)"up to 80% increase in the growth rate and enhanced photosynthetic capacity"
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PMID:38609451 - PARTIAL (IN_VITRO)"exchange of further molecules beyond the unidirectional feeding with sucrose"
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PMID:38609451 - SUPPORT (IN_VITRO)"which aligns with the expected outcome due to the same growth rate"
Associated Datasets
| Dataset | Type | Repository | Accession |
|---|---|---|---|
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MassIVE/GNPS multi-omics dataset for S. elongatus-P. putida coculture
Public MassIVE/GNPS dataset for the P. putida cscRABY and S. elongatus cscB multi-omics coculture study. |
METABOLOMICS | MASSIVE | MSV000092369 |
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ProteomeXchange/iProX proteomics dataset for S. elongatus-P. putida coculture
ProteomeXchange/iProX dataset associated with the S. elongatus cscB and P. putida cscRABY synthetic coculture multi-omics study. |
METAPROTEOMICS | OTHER | PXD045253 |
Knowledge gaps & discussions (1)
KNOWLEDGE_GAP OPEN Which mechanism causes cyanobacterial growth promotion in the cscRABY coculture?
The primary study supports conditional cyanobacterial growth benefit and carbon supply to Pseudomonas, while matched external-sucrose controls show no heterotroph growth advantage. Transport regulation and mixed-cell metabolomics suggest additional interactions but do not resolve donor-recipient flux or distinguish a specific mediator from growth-state differences. Do not transfer this feedback to the cscAB or DNT implementation without exact-system evidence.
Attaches to: ecological_interactions#Growth-Promoting Partner Feedback
1 evidence item(s)
attributing core metabolites to a specific co-culture partner is not possible
Explains why the omics findings cannot directly identify reciprocal transfer.
External Resources
| Name | Repository | Resource ID |
|---|---|---|
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Exact-system publication - PHA production from light and CO2
Primary publication establishing the S. elongatus cscB and P. putida cscAB species-pair platform for PHA production. |
OTHER | doi:10.1186/s13068-017-0875-0 |
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Exact-system publication - nitrate-blind P. putida PHA improvement
Follow-up publication using the same S. elongatus/P. putida species pair with engineered nitrate-blind P. putida for improved PHA production. |
OTHER | PMID:32523942 |
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Exact-system publication - DNT biotransformation
DOE-linked publication extending the S. elongatus/P. putida species-pair platform to 2,4-dinitrotoluene biotransformation and PHA production. |
OTHER | PMID:32064751 |
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Exact-system publication - multi-omics interaction study
Multi-omics publication on the same S. elongatus/P. putida species pair, using S. elongatus cscB and P. putida cscRABY to characterize interaction mechanisms. |
OTHER | PMID:38609451 |
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Environmental Factors
| Factor | Value | Unit |
|---|---|---|
| Light and CO2 | Illumination with CO2 as primary carbon input | N/A |
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| Nitrogen limitation and nitrate-blind engineering | Nitrogen-limited or nitrate-blind P. putida conditions | N/A |
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Growth Media
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