A two-species engineered biophotovoltaic consortium pairing engineered Synechococcus elongatus UTEX 2973 with engineered Shewanella oneidensis MR-1. The cyanobacterium converts light and carbon dioxide into D-lactate, and the exoelectrogenic Shewanella partner oxidizes D-lactate and transfers electrons to an anode. The system is relevant to DOE bioenergy and bioelectrochemical research because it demonstrates division of labor for renewable electricity production from photosynthesis, metabolite transfer, and extracellular electron transfer.
Taxonomy
| Taxon | Ontology ID | Functional Roles | Abundance |
|---|---|---|---|
| Synechococcus elongatus UTEX 2973 | NCBITaxon:1350461 · TaxonMech · TraitMech |
PRIMARY_PRODUCER
CROSS_FEEDER
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N/A |
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| Shewanella oneidensis MR-1 | NCBITaxon:211586 · TaxonMech · TraitMech |
CROSS_FEEDER
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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.
Photosynthetic D-Lactate Cross-Feeding
CROSS_FEEDINGEngineered Syn2973-omcS-ldh produces D-lactate that supports current production by the napA-deletion derivative of S. oneidensis MR-1. The engineered carrier is important but not the exclusive organic input: the paper reports additional cyanobacterial organics and LB supplementation in the consortium assays. Canonical member labels denote their strain backgrounds.
Source Taxon: Synechococcus elongatus UTEX 2973
Target Taxon: Shewanella oneidensis MR-1
Metabolites: D-lactate (CHEBI:16004 · MediaIngredientMech · CMMMech), carbon dioxide (CHEBI:16526 · MediaIngredientMech · CMMMech)
Biological Processes:
- photosynthesis (GO:0015979 · PathwayMech)
- interspecies interaction between organisms (GO:0044419 · PathwayMech)
Photosynthetically produced D-lactate is oxidized by the engineered Shewanella partner, supporting electron transfer to the anode. Lactate-free and axenic comparisons support its contribution, not exclusive attribution of all current to D-lactate.
Evidence
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PMID:31537786 - SUPPORT (IN_VITRO)"D-lactate mediated microbial consortium consisting of photosynthetic cyanobacteria and exoelectrogenic Shewanella"
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PMID:31537786 - SUPPORT (IN_VITRO)"D-lactate is selected as the energy carrier"
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PMID:31537786 - SUPPORT (IN_VITRO)"d-lactate which is the dominant secreted metabolite"
Shewanella Anode Electron Transfer
The napA-deletion S. oneidensis MR-1 derivative oxidizes D-lactate and transfers electrons to an abiotic anode. This is the consortium electrode-output process, not electron or metabolite donation to Synechococcus. The paper also reports enhanced cyanobacterial growth; it does not isolate CO2 recycling as its cause.
Participating Taxa: Shewanella oneidensis MR-1
Metabolites: D-lactate (CHEBI:16004 · MediaIngredientMech · CMMMech)
HYPOTHESIZED/PARTIAL: the source schematic proposes that CO2 released during Shewanella oxidation can be re-assimilated by cyanobacteria for D-lactate production. The reviewed main text does not demonstrate this carbon-return flux or identify it as the cause of cyanobacterial growth benefit; electrons flow to the anode, not the cyanobacterium.
Evidence
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PMID:31537786 - SUPPORT (IN_VITRO)"releases electrons from D-lactate and transfers them to the anode"
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PMID:31537786 - PARTIAL (IN_VITRO)"The released CO2 can be re-assimilated by cyanobacteria for d-lactate production."
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PMID:31537786 - SUPPORT (IN_VITRO)"enhanced the growth of cyanobacteria"
Spatial-Temporal Separation for Compatibility
Device-level temporal or spatial separation mitigated incompatible light and oxygen conditions for the Shewanella partner while preserving D-lactate transfer. This is an abiotic compatibility intervention, not colonization facilitation by cyanobacteria. The more-than-40-day spatial-temporal result additionally used continuous medium replenishment and LB supplementation; it is distinct from temporal batch and spatially separated assays.
Participating Taxa: Synechococcus elongatus UTEX 2973, Shewanella oneidensis MR-1
Evidence
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PMID:31537786 - SUPPORT (IN_VITRO)"Light-induced damage was also reflected in increased intracellular reactive oxygen species"
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PMID:31537786 - SUPPORT (IN_VITRO)"temporal/spatial separation design conquered the physiological incompatibility"
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PMID:31537786 - SUPPORT (IN_VITRO)"spatial-temporal separation setup with medium replenishment enables stable operation for over 40 days"
Knowledge gaps & discussions (1)
KNOWLEDGE_GAP OPEN Does Shewanella-derived CO2 contribute to cyanobacterial D-lactate production or growth?
The primary main text, Results and figure captions were inspected. Figure1 proposes CO2 re-assimilation and Results report cyanobacterial growth enhancement, but these do not isolate a carbon-return mediator. The anode remains the electron recipient. Preserve the existing reverse direction only as a hypothesis pending direct flux evidence; device separation and medium replenishment are distinct interventions.
Attaches to: ecological_interactions#Shewanella Anode Electron Transfer, ecological_interactions#Photosynthetic D-Lactate Cross-Feeding
1 evidence item(s)
The released CO2 can be re-assimilated by cyanobacteria for d-lactate production.
Source-proposed carbon recycling is not demonstrated electron return.
External Resources
| Name | Repository | Resource ID |
|---|---|---|
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Primary publication - Synechococcus-Shewanella biophotovoltaic consortium
Primary publication reporting a D-lactate-mediated photosynthetic cyanobacteria-Shewanella biophotovoltaic consortium. |
OTHER | PMID:31537786 |
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Open full text - Synechococcus-Shewanella biophotovoltaic consortium
Open-access full text with methods, engineered strain descriptions, and device organization. |
OTHER | PMCID:PMC6753107 |
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DOI landing page - Synechococcus-Shewanella biophotovoltaic consortium
DOI landing page for the Nature Communications publication. |
OTHER | doi:10.1038/s41467-019-12190-w |
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Environmental Factors
| Factor | Value | Unit |
|---|---|---|
| Light-driven charging phase | Continuous illumination with 3 percent carbon dioxide for cyanobacterial D-lactate production | N/A |
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| Medium and device compatibility | MBG11 medium with temporal, spatial, and spatial-temporal separation variants | N/A |
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| Long-duration power output | over 40 days with average power density of 135 mW per square meter | N/A |
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Growth Media
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