A defined synthetic obligate mutualism pairing auxotrophic Zymomonas mobilis with auxotrophic Escherichia coli. Exometabolomics of Z. mobilis spent medium identified amino acid exometabolites used to select E. coli proA, pheA, and ilvA auxotroph partners, while mutant fitness profiling selected a Z. mobilis ZMO0748 auxotroph whose rescue was linked to glutathione-related metabolites in E. coli spent medium. The system is DOE-relevant because it was developed by LBNL and Sandia researchers with DOE BER support as a synthetic microbial ecology platform for more resilient biotechnology processes.
Taxonomy
| Taxon | Ontology ID | Functional Roles | Abundance |
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| Zymomonas mobilis | NCBITaxon:542 · TaxonMech · TraitMech |
CROSS_FEEDER
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N/A |
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| Escherichia coli | NCBITaxon:562 · 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.
Zymomonas Amino Acid Rescue of E. coli Auxotrophs
CROSS_FEEDINGWild-type Z. mobilis ZM4 spent medium and individual amino-acid supplementation rescued the selected E. coli proA, pheA and ilvA auxotrophs. This supports nutritional rescue, beyond candidate selection alone. The reciprocal experiments paired each E. coli mutant separately with the Z. mobilis ZMO0748 mutant; they do not describe a four-member consortium or establish a dedicated export mechanism.
Source Taxon: Zymomonas mobilis
Target Taxon: Escherichia coli
Metabolites: amino acid (CHEBI:33709 · MediaIngredientMech · CMMMech)
Biological Processes:
- interspecies interaction between organisms (GO:0044419 · PathwayMech)
Partner spent-medium and amino-acid rescue support the nutritional contribution to the three separately tested reciprocal pairs. The molecular release route and all additional interactions are not resolved.
Evidence
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PMID:26885935 - SUPPORT (IN_VITRO)"Amino acid exometabolites identified in the spent medium of Z. mobilis"
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PMID:26885935 - SUPPORT (IN_VITRO)"used to select three corresponding E. coli auxotrophs"
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PMID:26885935 - SUPPORT (IN_VITRO)"they all successfully grew in 50% spent medium and metabolite supplemented medium"
E. coli Sulfur-Metabolite Rescue of Zymomonas Auxotroph
CROSS_FEEDINGE. coli spent medium rescued the Z. mobilis ZMO0748 cysteine-synthase-like mutant. Cysteine and glutathione supplementation independently supported rescue. Glutathione-related compounds were detected in spent medium, but free cysteine below detection was not excluded. Thus the phenotype is experimentally supported while the exact naturally transferred sulfur compound and release/uptake route remain PARTIAL.
Source Taxon: Escherichia coli
Target Taxon: Zymomonas mobilis
Metabolites: glutathione (CHEBI:16856 · MediaIngredientMech · CMMMech)
Biological Processes:
- interspecies interaction between organisms (GO:0044419 · PathwayMech)
PARTIAL molecular assignment: sulfur-metabolite rescue supports the ZMO0748 contribution to reciprocal growth, and glutathione is sufficient in supplementation. Its exclusive necessity in coculture and the exact exchanged sulfur species were not established.
Evidence
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PMID:26885935 - PARTIAL (IN_VITRO)"identified glutathione related metabolites as potentially available for rescue"
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PMID:26885935 - PARTIAL (IN_VITRO)"rescue of the Z. mobilis cysteine synthase mutant"
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PMID:26885935 - SUPPORT (IN_VITRO)"both cysteine and glutathione are capable of rescuing Z. mobilis"
Reciprocal Auxotroph Coculture Growth
MUTUALISMEach of three separate pairs containing the Z. mobilis ZMO0748 auxotroph and an E. coli proA, pheA or ilvA auxotroph grew in unsupplemented ZMMG, where the individual auxotrophs did not. Optical density and species-resolved flow cytometry support growth of both partners under those conditions. This does not establish long-term community stability or the absence of additional beneficial or inhibitory exchanges.
Source Taxon: Zymomonas mobilis
Target Taxon: Escherichia coli
Biological Processes:
- interspecies interaction between organisms (GO:0044419 · PathwayMech)
Evidence
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PMID:26885935 - SUPPORT (IN_VITRO)"Three sets of cocultures between the Z. mobilis auxotroph and each of the three E. coli auxotrophs"
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PMID:26885935 - SUPPORT (IN_VITRO)"monitored by optical density for growth"
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PMID:26885935 - SUPPORT (IN_VITRO)"analyzed by flow cytometry to confirm high cell counts for each species"
Knowledge gaps & discussions (1)
KNOWLEDGE_GAP OPEN Which sulfur species and cellular release/uptake routes mediate rescue in the live pairs?
Do not downgrade the positive spent-medium, supplementation and reciprocal-growth controls to mere correlation. Distinguish those controls from exclusive glutathione necessity and active secretion: alternative sulfur compounds and release by extracellular processing or lysis remain possible. The three pairs were tested separately; longitudinal stability was outside the reported experiment.
Attaches to: ecological_interactions#Zymomonas Amino Acid Rescue of E. coli Auxotrophs, ecological_interactions#E. coli Sulfur-Metabolite Rescue of Zymomonas Auxotroph, ecological_interactions#Reciprocal Auxotroph Coculture Growth
1 evidence item(s)
identified glutathione related metabolites as potentially available for rescue
The abstract itself distinguishes candidate sulfur metabolites from the demonstrated growth phenotype.
External Resources
| Name | Repository | Resource ID |
|---|---|---|
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Primary publication - exometabolomics-designed obligate mutualism
Primary publication reporting exometabolomics-assisted design and validation of Z. mobilis and E. coli synthetic obligate mutualisms. |
OTHER | PMID:26885935 |
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DOI landing page - exometabolomics-designed obligate mutualism
DOI landing page for the ACS Synthetic Biology article. |
OTHER | doi:10.1021/acssynbio.5b00236 |
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DOE PAGES record for the exact publication
DOE PAGES metadata for the publication, including LBNL and Sandia affiliations and DOE BER sponsorship. |
OTHER | OSTI:1429352 |
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Environmental Factors
| Factor | Value | Unit |
|---|---|---|
| Auxotrophic mutant selection | Z. mobilis ZMO0748 auxotroph with E. coli proA, pheA, or ilvA auxotrophs | N/A |
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| Exometabolomics-guided partner selection | Mass spectrometry-based exometabolomics of spent media | N/A |
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Growth Media
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