A synthetic lichen-inspired phototroph-heterotroph coculture pairing engineered sucrose-secreting Synechococcus elongatus PCC 7942 with the oleaginous yeast Rhodotorula glutinis. The cyanobacterium fixes carbon dioxide under illumination and exports sucrose, while R. glutinis consumes the cyanobacterial photosynthate, increases coculture biomass and lipid yield, and alleviates reactive oxygen stress that limits low-density cyanobacterial axenic growth.
Taxonomy
| Taxon | Ontology ID | Functional Roles | Abundance |
|---|---|---|---|
| Synechococcus elongatus PCC 7942 cscB+ — ontology label: Synechococcus elongatus | NCBITaxon:32046 · TaxonMech · TraitMech |
PRIMARY_PRODUCER
CROSS_FEEDER
|
N/A |
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| Rhodotorula glutinis | NCBITaxon:5535 · 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.
Photosynthetic Sucrose Provisioning
CROSS_FEEDINGSucrose-secreting S. elongatus supplies carbon used by R. glutinis in the synthetic lichen coculture. Yeast growth and lower residual sucrose support feeding. The result is strain-specific: the tested S. cerevisiae pairing did not grow comparably. CO2 is fixed by the phototroph rather than donated as the organic carbon substrate.
Source Taxon: Synechococcus elongatus PCC 7942 cscB+
Target Taxon: Rhodotorula glutinis
Metabolites: sucrose (CHEBI:17992 · MediaIngredientMech · CMMMech), carbon dioxide (CHEBI:16526 · MediaIngredientMech · CMMMech)
Biological Processes:
- photosynthesis (GO:0015979 · PathwayMech)
- sucrose biosynthetic process (GO:0005986 · PathwayMech)
Cyanobacterial sucrose supports yeast growth within the consortium that exhibits greater total biomass and fatty-acid yield. The whole-culture comparison does not resolve the partners' separate lipid contributions or a sucrose-to-lipid carbon balance.
Evidence
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doi:10.1186/s13068-017-0736-x - SUPPORT (IN_VITRO)"R. glutinis and C. curvatus grew efficiently and utilized sucrose produced by the partner in co-culture"
Rhodotorula-Enhanced Cyanobacterial Survival
MUTUALISMR. glutinis supports cyanobacterial growth while receiving sucrose, consistent with conditional mutualism. In illuminated HEPES-buffered cultures, peroxide measurements and catalase-rescue comparisons support protection against oxidative stress, especially for dilute cyanobacterial inocula. High-density axenic growth remains possible. Yeast enhances growth beyond catalase alone, so peroxide removal is not the sole demonstrated explanation and the additional benefit is unresolved.
Source Taxon: Rhodotorula glutinis
Target Taxon: Synechococcus elongatus PCC 7942 cscB+
Metabolites: hydrogen peroxide (CHEBI:16240 · MediaIngredientMech · CMMMech)
Biological Processes:
- response to oxidative stress (GO:0006979 · PathwayMech)
HYPOTHESIZED/PARTIAL: protection against oxidative stress could help maintain the phototrophic partner that supports lipid-producing coculture. The ROS/catalase comparisons do not isolate the contribution of that protection to the separately measured whole-culture fatty-acid yield advantage.
Evidence
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doi:10.1186/s13068-017-0736-x - SUPPORT (IN_VITRO)"cyanobacterial growth in co-culture with R. glutinis was significantly superior to axenic growth"
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doi:10.1186/s13068-017-0736-x - SUPPORT (IN_VITRO)"HOOH content was progressively reduced and efficiently minimized"
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doi:10.1186/s13068-017-0736-x - SUPPORT (IN_VITRO)"S. elongatus grew better in the cultures with catalase"
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doi:10.1186/s13068-017-0736-x - SUPPORT (IN_VITRO)"the axenic growth of S. elongatus was robust"
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doi:10.1186/s13068-017-0736-x - PARTIAL (IN_VITRO)"R. glutinis may be providing factors beyond HOOH reduction"
Lipid Production Enhancement
S. elongatus-R. glutinis cultures persisted for more than one month in batch and semi-continuous formats. Batch total fatty-acid yield was 54% higher than in cyanobacterial monoculture, alongside increased total biomass. These are whole-culture endpoints, not an additional exchange or a measurement of yeast-specific lipid output. Semi-continuous total harvest includes withdrawn material and is not equivalent to final biomass alone.
Participating Taxa: Synechococcus elongatus PCC 7942 cscB+, Rhodotorula glutinis
Metabolites: sucrose (CHEBI:17992 · MediaIngredientMech · CMMMech)
Biological Processes:
- sucrose catabolic process (GO:0005987 · PathwayMech)
- lipid biosynthetic process (GO:0008610 · PathwayMech)
Evidence
-
doi:10.1186/s13068-017-0736-x - SUPPORT (IN_VITRO)"The total fatty acids (TFA) in the batch co-culture was 54% higher than in mono-culture"
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doi:10.1186/s13068-017-0736-x - SUPPORT (IN_VITRO)"With addition of the 50 mL of culture that was removed both at 10 and 21 days"
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doi:10.1186/s13068-017-0736-x - SUPPORT (IN_VITRO)"were sustained over 1 month in both batch and in semi-continuous culture"
Associated Datasets
| Dataset | Type | Repository | Accession |
|---|---|---|---|
|
Artificial lichen coculture publication
Open-access study reporting growth, sucrose use, ROS, biomass, and lipid measurements for S. elongatus-yeast artificial lichen cocultures. |
PHENOTYPE | OTHER | doi:10.1186/s13068-017-0736-x |
Knowledge gaps & discussions (1)
KNOWLEDGE_GAP OPEN How much of the lipid-yield benefit is mediated by ROS relief rather than other partner effects?
Peroxide measurements and catalase rescue support ROS protection, but the primary growth benefit exceeds catalase alone and the lipid assay measures the mixed culture. Do not infer an identified additional factor, exclusive ROS mediation or yeast-specific lipid yield from these comparisons.
Attaches to: ecological_interactions#Rhodotorula-Enhanced Cyanobacterial Survival, ecological_interactions#Lipid Production Enhancement
1 evidence item(s)
R. glutinis may be providing factors beyond HOOH reduction
The source identifies an unresolved contribution beyond peroxide reduction.
Environmental Factors
| Factor | Value | Unit |
|---|---|---|
| modified BG-11 coculture medium | BG-11[co] with YNB without amino acids, ammonium chloride, IPTG, HEPES, and NaCl | N/A |
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| illumination and carbon dioxide | 16:8 hour light/dark cycle with carbon dioxide-enriched air | N/A |
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Growth Media
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