A defined four-member panel of microorganisms tested for their ability to grow on actual martian regolith, supplied as sawdust of the Mars meteorite EETA79001, rather than on a terrestrial simulant. The panel comprises the bacterium Escherichia coli B, the two cyanobacteria Eucapsis sp. and Chroococcidiopsis sp. strain Chr20-20201027-1, and the cold-adapted bacterium Planococcus halocryophilus. Each organism was cultivated separately on EETA79001 sawdust for up to 23 days under terrestrial conditions across regolith:water ratios from 4:1 to 1:10; the study demonstrates that real martian regolith can support microbial growth and does not contain bactericidal agents. The panel is an astrobiology / In-Situ Resource Utilization model relevant to putative martian life and to bio-sustainable human habitats on Mars. Members were assayed individually, so the record captures a shared capacity to grow on martian regolith rather than measured interspecies interactions.
Taxonomy
| Taxon | Ontology ID | Functional Roles | Abundance |
|---|---|---|---|
| Escherichia coli B — ontology label: Escherichia coli | NCBITaxon:562 · TaxonMech · TraitMech | N/A | |
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| Eucapsis sp. — ontology label: Eucapsis | NCBITaxon:1521555 · TaxonMech · TraitMech | N/A | |
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| Chroococcidiopsis sp. Chr20-20201027-1 — ontology label: Chroococcidiopsis | NCBITaxon:54298 · TaxonMech · TraitMech | N/A | |
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| Planococcus halocryophilus | NCBITaxon:1215089 · TaxonMech · TraitMech | 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.
EETA79001 Mineral Nutrient Supply
The organisms were assayed separately, not as a coculture. COMMUNITY_LEVEL is retained as the current container for shared abiotic/panel observations, not evidence of emergent community activity; record-model placement remains OPEN under #573. EETA79001 sawdust supplied the intended nutrient substrate under terrestrial laboratory conditions. Earlier leachate analyses cited in the paper reported phosphate, nitrate, sulfate and calcium among candidate resources; the growth experiment did not quantify uptake or selectively test each ion. This low-perchlorate meteorite is not representative of all Martian surface regolith, and the assay does not establish growth in a Mars atmosphere, absence of toxicity generally or a complete regolith-derived carbon budget.
Participating Taxa: Escherichia coli B, Eucapsis sp., Chroococcidiopsis sp. Chr20-20201027-1, Planococcus halocryophilus
Metabolites: phosphate (CHEBI:18367 · MediaIngredientMech · CMMMech), nitrate (CHEBI:17632 · MediaIngredientMech · CMMMech), sulfate (CHEBI:16189 · MediaIngredientMech · CMMMech), calcium(2+) (CHEBI:29108 · MediaIngredientMech · CMMMech)
PARTIAL - hydration can make meteorite-associated resources available and thereby support growth or persistence in the separate cultures. Regolith/water treatments and water-only controls support a substrate contribution for some organisms, but ion-specific mediation was not isolated and E. coli also persisted in water-only controls.
Evidence
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PMID:38665180 - SUPPORT (IN_VITRO)"Our work was aimed at directly observing the effect of martian regolith on the growth and continued survival of bacteria, where the sole nutrient source was the regolith."
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PMID:38665180 - SUPPORT (IN_VITRO)"The EETA79001 leachate includes sufficient amounts of inorganic nutrients necessary for bacterial growth"
Hydration-dependent regolith growth and survival
The organisms were assayed separately, not as a coculture. COMMUNITY_LEVEL is retained as the current container for shared abiotic/panel observations, not evidence of emergent community activity; record-model placement remains OPEN under #573. Water-amended 20 mg sawdust treatments supported condition-dependent growth and survival over about 22-23 days. The wetter treatments generally prolonged heterotroph recovery; dry-design controls still received a wet inoculum. Cyanobacterial most-probable-number recovery after resuscitation and bacterial CFU plating measure different viable-recovery endpoints, not direct continuous cell production or comparable biomass flux. The regolith:water series and water-only controls should not be conflated into a single growth condition or a guarantee that every organism proliferated.
Participating Taxa: Escherichia coli B, Eucapsis sp., Chroococcidiopsis sp. Chr20-20201027-1, Planococcus halocryophilus
Metabolites: water (CHEBI:15377 · MediaIngredientMech · CMMMech)
Biological Processes:
- growth (GO:0040007 · PathwayMech)
Evidence
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PMID:38665180 - SUPPORT (IN_VITRO)"Using the EETA79001 sawdust as a substrate with different ratios of regolith:water (Fig. 1 ), we have investigated the growth and survival of four non-spore-forming microorganisms under terrestrial conditions."
Strain-specific regolith persistence
The organisms were assayed separately, not as a coculture. COMMUNITY_LEVEL is retained as the current container for shared abiotic/panel observations, not evidence of emergent community activity; record-model placement remains OPEN under #573. Chr20 maintained or increased recoverable counts more successfully than Eucapsis, while Planococcus halocryophilus showed strong early growth relative to E. coli in regolith. Planococcus late persistence depended on hydration, chiefly the wettest 1:5 condition; most other ratios fell below quantification after approximately 14-17 days. E. coli survived in water alone and declined from its starting count in regolith. Unequal initial phototroph counts, MPN versus CFU methods and differing water ratios preclude a pooled universal extremophile-fitness ranking. Below quantification does not establish extinction.
Participating Taxa: Escherichia coli B, Eucapsis sp., Chroococcidiopsis sp. Chr20-20201027-1, Planococcus halocryophilus
Biological Processes:
- growth (GO:0040007 · PathwayMech)
Evidence
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PMID:38665180 - PARTIAL (IN_VITRO)"Chr20 fared much better than Eucapsis by an order of magnitude and was able to survive and proliferate beyond its initial viable count regardless of the regolith:water ratio for the 22 days"
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PMID:38665180 - PARTIAL (IN_VITRO)"P. halocryophilus growth and survival was significantly better in the regolith at all ratios than the E. coli and showed strong growth overall."
Knowledge gaps & discussions (1)
KNOWLEDGE_GAP OPEN Which abiotic resources explain strain-specific growth in the separate meteorite assays?
Preserve positive growth/persistence and hydration contrasts without niche partitioning or a procedure-to-result arrow. Nutrient-specific uptake, carbon provenance, evaporation and salt effects are unresolved mechanisms. The current panel container is explicitly provisional under existing #573, not a resolved community model. #1584 repairs the graph and #1586 tracks stale zero-interaction and vessel/volume metadata; prior #574 panel framing preserved. Main text/captions read, not Supplementary Note 1, original images or raw counts. No new structure.
Attaches to: ecological_interactions#EETA79001 Mineral Nutrient Supply, ecological_interactions#Hydration-dependent regolith growth and survival, ecological_interactions#Strain-specific regolith persistence
Environmental Factors
| Factor | Value | Unit |
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| Actual martian regolith substrate (Mars meteorite EETA79001) | EETA79001 meteorite sawdust | N/A |
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| Regolith-to-water ratio | 4:1 to 1:10 (regolith:water) | N/A |
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Growth Media
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