An anaerobic-digestion microbial consortium studied as part of a bioregenerative life-support concept for Mars: cyanobacterial biomass (Anabaena sp.), which can be grown on Martian resources, is anaerobically digested to mobilize nutrients (ammonium and phosphate) for use as a crop fertilizer, with biogas as a co-product. Ramalho et al. (2025, Bioresource Technology) tested three microbial communities for their ability to digest Anabaena biomass in three matrices — a minimal medium, 200 g/L MGS-1 Mars regolith simulant, and water. In minimal medium the taxonomic (16S) analysis revealed a SYNTROPHIC community: fermentative bacteria degrade the cyanobacterial biomass and cross-feed hydrogenotrophic methanogenic archaea (interspecies H2/CO2 transfer driving methanogenesis). In the MGS-1 regolith matrix, however, the methanogens were outcompeted by sulfate-reducing bacteria, and the regolith also adsorbed organics and lowered phosphate/ammonium recovery. The Anabaena biomass here is the digestion FEEDSTOCK (substrate) rather than a live member of the digesting consortium. All communities produced ammonium and removed organic carbon, supporting the viability of a Mars-relevant bioprocess for fertilizer production. The specific dominant genera resolved by the paper's 16S analysis are reported in the full text, which is paywalled; only the functional guilds (fermentative bacteria, hydrogenotrophic methanogens, sulfate-reducing bacteria) are named in the openly available abstract and are therefore represented here as interactions/roles rather than as NCBITaxon-grounded members.
Taxonomy
| Taxon | Ontology ID | Functional Roles | Abundance |
|---|---|---|---|
| Anabaena sp. (cyanobacterial digestion feedstock) — ontology label: Anabaena | NCBITaxon:1163 · TaxonMech · TraitMech |
PRIMARY_PRODUCER
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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.
Anabaena Biomass Anaerobic Digestion
Anaerobic communities digested supplied Anabaena biomass in minimal medium, MGS-1 regolith suspension or water. Ammonium and organic-carbon endpoints were measured separately from taxonomic interpretations of the active guilds.
Metabolites: ammonium (CHEBI:28938 · MediaIngredientMech · CMMMech)
Biological Processes:
- biological process involved in interspecies interaction between organisms (GO:0044419 · PathwayMech)
HYPOTHESIZED - fermentation of the supplied biomass could provide hydrogen and carbon dioxide to the methanogens detected in minimal medium; partner-specific transfer was inferred from taxonomy.
Biomass digestion released ammonium and reduced organic-carbon measures in the tested matrices; total COD could not be evaluated in the regolith suspension.
Evidence
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PMID:40089033 - SUPPORT (IN_VITRO)"tested the abilities of three microbial communities to digest the biomass of Anabaena sp. in minimal medium "
Fermenter-to-methanogen syntrophy (interspecies H2/CO2 transfer)
SYNTROPHYHYPOTHESIZED - fermentative bacteria and hydrogenotrophic methanogens detected in minimal medium could cooperate through hydrogen/carbon-dioxide transfer. Taxonomic composition supports this proposed syntrophy, not measured partner-resolved flux. Acetate consumption is not assigned to the hydrogenotrophic methanogens.
Metabolites: dihydrogen (CHEBI:18276 · MediaIngredientMech · CMMMech), carbon dioxide (CHEBI:16526 · MediaIngredientMech · CMMMech), methane (CHEBI:16183 · MediaIngredientMech · CMMMech)
Biological Processes:
- methanogenesis (GO:0015948 · PathwayMech)
- biological process involved in interspecies interaction between organisms (GO:0044419 · PathwayMech)
Evidence
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PMID:40089033 - PARTIAL (IN_VITRO)"taxonomic analysis revealed a syntrophic fermentative community and"
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PMID:40089033 - PARTIAL (IN_VITRO)"hydrogenotrophic methanogens in minimal medium, but methanogens were outcompeted"
Candidate Sulfate-Reducer Competition in MGS-1 Regolith
HYPOTHESIZED - sulfate-reducer enrichment and failure to amplify archaeal markers in the MGS-1 condition were interpreted as consistent with competition against methanogens. Matrix inhibition is also possible; amplification failure is not a direct measurement of zero methane production.
Metabolites: dihydrogen (CHEBI:18276 · MediaIngredientMech · CMMMech), sulfate (CHEBI:16189 · MediaIngredientMech · CMMMech)
Biological Processes:
- dissimilatory sulfate reduction (GO:0019420 · PathwayMech)
Evidence
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PMID:40089033 - PARTIAL (IN_VITRO)"in MGS-1 by sulfate-reducing bacteria."
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PMID:40089033 - PARTIAL (IN_VITRO)"hydrogenotrophic methanogens in minimal medium, but methanogens were outcompeted"
Ammonium Production and Organic Carbon Removal
Ammonium was produced and organic-carbon measures declined across the tested digestion matrices. Regolith interfered with total-COD determination, so soluble-COD results in that condition must not be presented as measured total-carbon removal.
Metabolites: ammonium (CHEBI:28938 · MediaIngredientMech · CMMMech)
Biological Processes:
- biological process involved in interspecies interaction between organisms (GO:0044419 · PathwayMech)
Evidence
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PMID:40089033 - SUPPORT (IN_VITRO)"All communities produced ammonium and removed organic carbon in all"
MGS-1 Nutrient Recovery Penalty
PARTIAL - the MGS-1 matrix reduced recovered phosphate and ammonium relative to the other conditions. Adsorption and precipitation were proposed explanations; sulfate-reducer competition was not demonstrated to cause the nutrient-recovery penalty.
Metabolites: ammonium (CHEBI:28938 · MediaIngredientMech · CMMMech)
Biological Processes:
- biological process involved in interspecies interaction between organisms (GO:0044419 · PathwayMech)
Evidence
-
PMID:40089033 - SUPPORT (IN_VITRO)"adsorbed organics and reduced the phosphate and ammonium recovery efficiency"
Knowledge gaps & discussions (1)
KNOWLEDGE_GAP OPEN Which guild fluxes and mineral processes explain digestion and nutrient recovery in each matrix?
PMID:40089033 distinguishes measured nutrient/COD endpoints from taxonomic guild inferences. No archaeal amplification in MGS-1 does not quantify methane flux. The regolith treatment changes multiple variables; adsorption/precipitation and microbial competition cannot be collapsed into one causal chain. Primary full-text passages were read through the public author copy, but supplements were not reviewed.
Attaches to: ecological_interactions#Anabaena Biomass Anaerobic Digestion, ecological_interactions#Fermenter-to-methanogen syntrophy (interspecies H2/CO2 transfer), ecological_interactions#Candidate Sulfate-Reducer Competition in MGS-1 Regolith, ecological_interactions#Ammonium Production and Organic Carbon Removal, ecological_interactions#MGS-1 Nutrient Recovery Penalty
External Resources
| Name | Repository | Resource ID |
|---|---|---|
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Primary publication - anaerobic digestion of cyanobacterial biomass for Mars fertilizer
Ramalho et al. 2025, Bioresource Technology — tests three microbial communities for anaerobic digestion of Anabaena sp. biomass in minimal medium, 200 g/L MGS-1 Mars regolith simulant, and water, for Mars crop-fertilizer production. |
OTHER | doi:10.1016/j.biortech.2025.132383 |
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NCBI Taxonomy - Anabaena
NCBI Taxonomy record for the genus Anabaena (cyanobacterial digestion feedstock). |
OTHER | NCBITaxon:1163 |
Environmental Factors
| Factor | Value | Unit |
|---|---|---|
| MGS-1 Mars regolith simulant matrix | 200 g/L MGS-1 Mars global simulant | N/A |
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| Anaerobic-digestion nutrient outputs | ammonium production and organic-carbon removal | N/A |
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