A defined three-species bacterial panel flown as the ESA BioRock experiment on board the International Space Station to test microbial bioleaching of economically important elements from basaltic rock under microgravity, simulated Mars gravity, and simulated Earth gravity (with ground 1 x g controls). Sphingomonas desiccabilis CP1D (DSM 16792), Bacillus subtilis NCIB 3610 (DSM 10), and Cupriavidus metallidurans CH34 (DSM 2839) were each cultivated on slides of olivine basalt (collected near Gufunes, Reykjavik, Iceland; chosen as an analogue of Moon/Mars surface material) inside a purposely designed miniature biomining reactor housed in the KUBIK incubator. Sphingomonas desiccabilis enhanced mean leached concentrations of rare earth elements (the lanthanides plus yttrium) relative to non-biological controls in all gravity regimes, while Bacillus subtilis reduced REE bioleaching efficacy and Cupriavidus metallidurans showed no difference, demonstrating the microbial specificity of the process as on Earth. A companion analysis showed that Sphingomonas desiccabilis and Bacillus subtilis both enhanced vanadium leaching by 184.92 to 283.22% relative to sterile controls, and a third study found no significant differences in final bacterial cell concentrations between gravity regimes. Gravity level had no significant effect on mean leaching in any case, establishing the principle of biomining and associated bioindustrial processes on Solar System bodies with non-1 x g gravity.
Taxonomy
| Taxon | Ontology ID | Functional Roles | Abundance |
|---|---|---|---|
| Sphingomonas desiccabilis CP1D — ontology label: Sphingomonas desiccabilis | NCBITaxon:429134 · TaxonMech · TraitMech |
PRIMARY_DEGRADER
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N/A |
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| Bacillus subtilis NCIB 3610 — ontology label: Bacillus subtilis | NCBITaxon:1423 · TaxonMech · TraitMech |
PRIMARY_DEGRADER
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N/A |
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| Cupriavidus metallidurans CH34 — ontology label: Cupriavidus metallidurans | NCBITaxon:119219 · 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.
Sphingomonas desiccabilis rare-earth-element bioleaching from basalt
Independently inoculated S. desiccabilis cultures raised mean leached concentrations of fourteen measured lanthanides from basalt. The pooled comparison with non-biological controls was significant in simulated Mars/Earth gravity but not microgravity (p=0.124); individual-element results also vary. Yttrium and scandium were not measured. Nonsignificant pooled gravity effects are not equivalence tests, and bulk elemental analysis does not resolve ionic speciation. This is a single-strain microbe-mineral outcome, not a coculture interaction.
Participating Taxa: Sphingomonas desiccabilis CP1D
Evidence
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PMID:33173035 - SUPPORT (IN_VITRO)"Sphingomonas desiccabilis enhanced mean leached concentrations of REEs compared to non-biological controls in all gravity conditions"
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PMID:33173035 - SUPPORT (IN_VITRO)"Content of rare earth elements (REEs; reported as μg/g"
Vanadium bioleaching by Sphingomonas desiccabilis and Bacillus subtilis
Separately inoculated S. desiccabilis and B. subtilis cultures yielded 184.92-283.22% OF the corresponding sterile-control vanadium concentrations in the ISS experiments, equivalent to increases of 84.92-183.22%. Main results clarify the abstract wording. ISS enhancement was significant, whereas the ground-control comparisons were not. These single-strain outcomes do not establish niche partitioning or a combined consortium benefit, and nonsignificant gravity effects do not prove equivalence.
Participating Taxa: Sphingomonas desiccabilis CP1D, Bacillus subtilis NCIB 3610
Evidence
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PMID:33868198 - SUPPORT (IN_VITRO)"Sphingomonas desiccabilis and Bacillus subtilis enhanced the leaching of vanadium under the three gravity conditions compared to sterile controls by 184.92 to 283.22%"
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PMID:33868198 - SUPPORT (IN_VITRO)"One element of interest in mining is vanadium (V)"
Microbial specificity of basalt bioleaching among panel members
The three separately cultured BioRock panel members differed in mean REE leaching. S. desiccabilis increased means; B. subtilis reduced means with significant pooled contrasts in microgravity/Mars but not simulated Earth gravity (p=0.055) or the ground comparison. C. metallidurans pooled contrasts were nonsignificant. These comparisons do not demonstrate reciprocal fitness effects, interspecies niche partitioning or equal outcomes across gravity conditions.
Participating Taxa: Sphingomonas desiccabilis CP1D, Bacillus subtilis NCIB 3610, Cupriavidus metallidurans CH34
Evidence
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PMID:33173035 - SUPPORT (IN_VITRO)"Bacillus subtilis exhibited a reduction in bioleaching efficacy and Cupriavidus metallidurans showed no difference compared to non-biological controls"
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PMID:33173035 - SUPPORT (IN_VITRO)"showing the microbial specificity of the process, as on Earth"
Knowledge gaps & discussions (1)
KNOWLEDGE_GAP OPEN Which measured processes account for strain-specific basalt leaching?
Three main papers were read, but figures, supplements, raw data and omitted equations were not inspected. The panel uses independent strain cultures, not coculture. EPS/contact and acid mechanisms remain hypotheses; post-fixation acidification and storage complicate interpretation. ICP measurements do not establish free-ion species. Non-graph percentage, yttrium, significance and inoculation wording remains under #1268; previously removed summary arrows stay absent.
Attaches to: ecological_interactions#Sphingomonas desiccabilis rare-earth-element bioleaching from basalt, ecological_interactions#Vanadium bioleaching by Sphingomonas desiccabilis and Bacillus subtilis, ecological_interactions#Microbial specificity of basalt bioleaching among panel members
External Resources
| Name | Repository | Resource ID |
|---|---|---|
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Primary publication - REE extraction in microgravity and Mars gravity
Nature Communications 2020 primary publication reporting rare earth element bioleaching from basalt by the BioRock panel on the ISS. |
OTHER | doi:10.1038/s41467-020-19276-w |
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Companion publication - vanadium mining and bioremediation
Frontiers in Microbiology 2021 companion publication reporting microbially-enhanced vanadium leaching by the BioRock panel under micro- and Mars gravity. |
OTHER | doi:10.3389/fmicb.2021.641387 |
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Companion publication - final bacterial cell concentrations
Frontiers in Microbiology 2020 companion publication reporting no significant effect of microgravity or simulated Mars gravity on final bacterial cell concentrations, with detailed cultivation methods for the three-species panel. |
OTHER | doi:10.3389/fmicb.2020.579156 |
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NCBI Taxonomy - Sphingomonas desiccabilis
NCBI Taxonomy record for Sphingomonas desiccabilis. |
OTHER | NCBITaxon:429134 |
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NCBI Taxonomy - Bacillus subtilis
NCBI Taxonomy record for Bacillus subtilis. |
OTHER | NCBITaxon:1423 |
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NCBI Taxonomy - Cupriavidus metallidurans
NCBI Taxonomy record for Cupriavidus metallidurans. |
OTHER | NCBITaxon:119219 |
Environmental Factors
| Factor | Value | Unit |
|---|---|---|
| Gravity regime | microgravity, simulated Mars gravity, and simulated Earth gravity (plus ground 1 x g controls) | N/A |
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| Basalt substrate | olivine basalt slides (Gufunes, Reykjavik, Iceland) | N/A |
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| Incubation temperature and duration | 21 days at ~20 C | N/A |
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Growth Media
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