A defined set of phosphorus-solubilizing bacteria (PSBs) assembled to improve the fertility of lunar regolith simulant for in-situ resource utilization (ISRU) agriculture in bioregenerative life support systems. Five commonly used microbial-fertilizer strains were tested on a CAS-1 lunar soil simulant: Bacillus mucilaginosus (AS1.232), Bacillus megaterium (AS1.217), Bacillus subtilis (CMCC 63501), Bacillus licheniformis (ATCC 11946), and Pseudomonas fluorescens (ATCC 13525). In a 21-day bio-improving experiment followed by a 24-day Nicotiana benthamiana cultivation experiment, three of the strains - Bacillus mucilaginosus, Bacillus megaterium, and Pseudomonas fluorescens - tolerated the lunar regolith simulant conditions and dissociated insoluble inorganic phosphorus from the simulant. The mechanism is chemolithoheterotrophic organic-acid production: the bacteria synthesize organic acids (e.g. oxalic, citric, tartaric acids) from carbon sources in the medium, lowering the pH and chelating metal ions in insoluble phosphates such as Ca3(PO4)2, FePO4, and AlPO4, thereby releasing available phosphate. PSB treatment raised the available phosphorus content of the simulant and promoted Nicotiana benthamiana growth, with the largest improvement when the simulant was pre-cultured with PSBs 18 days before sowing. The work establishes a microbiological route to convert lunar regolith into a plant-cultivation substrate for future lunar bases.
Taxonomy
| Taxon | Ontology ID | Functional Roles | Abundance |
|---|---|---|---|
| Bacillus mucilaginosus (AS1.232) — ontology label: Paenibacillus mucilaginosus | NCBITaxon:61624 · TaxonMech · TraitMech | N/A | |
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| Bacillus megaterium (AS1.217) — ontology label: Priestia megaterium | NCBITaxon:1404 · TaxonMech · TraitMech | N/A | |
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| Pseudomonas fluorescens (ATCC 13525) — ontology label: Pseudomonas fluorescens | NCBITaxon:294 · TaxonMech · TraitMech | N/A | |
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| Bacillus subtilis (CMCC 63501) — ontology label: Bacillus subtilis | NCBITaxon:1423 · TaxonMech · TraitMech | N/A | |
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| Bacillus licheniformis (ATCC 11946) — ontology label: Bacillus licheniformis | NCBITaxon:1402 · 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.
PSB Particle-Associated Biomass Phosphorus
In five separate individual-strain flask treatments, attached microbial biomass phosphorus tracked inferred insoluble-phosphorus dissociation. The attached pool increased after day 4 for B. mucilaginosus, B. megaterium and P. fluorescens, while most microbial biomass phosphorus remained suspended. This is an operational biomass-P and regression observation, not direct biofilm imaging or a selective attachment perturbation. HYPOTHESIZED - particle-associated biofilms could concentrate proton or organic-acid action, but the proposed bacteria-mineral microenvironment was not demonstrated. The five participants identify the tested panel, not a five-strain coculture.
Participating Taxa: Bacillus mucilaginosus (AS1.232), Bacillus megaterium (AS1.217), Pseudomonas fluorescens (ATCC 13525), Bacillus subtilis (CMCC 63501), Bacillus licheniformis (ATCC 11946)
Evidence
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PMID:37945659 - SUPPORT (IN_VITRO)"Suspended microbial biomass phosphorus was always much higher than attached microbial biomass phosphorus among all five PSB treatments"
PSB Phosphorus Mobilization In Regolith Simulant
Individual-strain flasks with terrestrial CAS-1-type regolith simulant and glucose broth showed increased total available phosphorus for B. mucilaginosus, B. megaterium and P. fluorescens; B. subtilis and B. licheniformis had little dissociation activity. Total available phosphorus includes dissolved, biomass and adsorbed pools and is not identical to freely dissolved inorganic phosphate. Low pH and attached biomass phosphorus correlated with inferred dissociation. HYPOTHESIZED - acidification and organic-acid chelation may contribute, but specific secreted oxalate or citrate, mediator necessity and interspecies nutrient transfer were not measured. The five canonical participants are separate tested strains, not an experimentally demonstrated cross-feeding community.
Participating Taxa: Bacillus mucilaginosus (AS1.232), Bacillus megaterium (AS1.217), Pseudomonas fluorescens (ATCC 13525), Bacillus subtilis (CMCC 63501), Bacillus licheniformis (ATCC 11946)
Metabolites: phosphate (CHEBI:18367 · MediaIngredientMech · CMMMech)
Evidence
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PMID:37945659 - SUPPORT (IN_VITRO)"the total available phosphorus capacity could be significantly increased by B. mucilaginosus, B. megaterium, and P. fluorescens"
Nicotiana Response To PSB-Conditioned Regolith Simulant
Living Nicotiana benthamiana plants grew better on simulant conditioned with the three effective PSBs, with the strongest measured response after 18 days of pretreatment. At 24 days after sowing, fresh weight and chlorophyll were 315.92% and 204.08% of the sterilized control, respectively; these are percentages of control, not percentage increases. Without pretreatment, seedling length at day 6 was only 53.28% of control. The three strains were mixed 1:1:1 by volume; blank and steam-killed controls were not pre-cultured. MS nutrient supplementation from day 6 contributed phosphorus. These results support a conditioning-treatment effect, not exclusive phosphorus mediation, universal early benefit or actual lunar-environment performance. The listed participants are inoculants, not the missing canonical plant host.
Participating Taxa: Bacillus mucilaginosus (AS1.232), Bacillus megaterium (AS1.217), Pseudomonas fluorescens (ATCC 13525)
Metabolites: phosphate (CHEBI:18367 · MediaIngredientMech · CMMMech)
Evidence
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PMID:37945659 - SUPPORT (IN_VIVO)"the growth of Nicotiana benthamiana could be most improved by treating the regolith simulant with PSBs 18 days before sowing"
Knowledge gaps & discussions (1)
KNOWLEDGE_GAP OPEN Which processes mediate regolith phosphorus mobilization and the time-dependent plant response?
Retain measured attachment pools, phosphorus mobilization and plant outcomes without the two untested mediation arrows. Separate five individual-strain flask treatments from three-strain plant inoculation. Biofilms and named organic acids are hypotheses; correlated phosphorus pools are not a selective mediator test. MS supplementation after day6, unconditioned controls and the adverse early unconditioned-treatment response limit exclusive-P attribution. Full primary body and embedded tables were read. The complete 2026 correction PMID:42304108 changes Fig1 particle-size labels, not the biology; no original figure pixels or separate supplementary measurement methods were audited. Non-graph mechanism, host, medium and assay metadata remain under #1564.
Attaches to: ecological_interactions#PSB Particle-Associated Biomass Phosphorus, ecological_interactions#PSB Phosphorus Mobilization In Regolith Simulant, ecological_interactions#Nicotiana Response To PSB-Conditioned Regolith Simulant
External Resources
| Name | Repository | Resource ID |
|---|---|---|
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Primary publication - phosphorus-solubilizing bacteria improve Nicotiana benthamiana on lunar regolith simulant
Xia et al., Communications Biology (2023). Primary source describing the five tested PSB strains, phosphorus solubilization from CAS-1 lunar regolith simulant, and improved Nicotiana benthamiana growth. |
OTHER | doi:10.1038/s42003-023-05391-z |
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NCBI Taxonomy - Paenibacillus mucilaginosus
NCBI Taxonomy record for Paenibacillus mucilaginosus (reported as Bacillus mucilaginosus). |
OTHER | NCBITaxon:61624 |
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NCBI Taxonomy - Priestia megaterium
NCBI Taxonomy record for Priestia megaterium (reported as Bacillus megaterium). |
OTHER | NCBITaxon:1404 |
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NCBI Taxonomy - Pseudomonas fluorescens
NCBI Taxonomy record for Pseudomonas fluorescens. |
OTHER | NCBITaxon:294 |
Environmental Factors
| Factor | Value | Unit |
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| Lunar regolith simulant substrate | CAS-1 lunar soil simulant | N/A |
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| Available phosphorus increase in liquid medium | soluble inorganic phosphorus increased by 212 percent | N/A |
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| Acidification as the phosphorus-dissolving factor | bacterial acidic substances lower pH | N/A |
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Growth Media
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