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L-chondrite meteorite primary resource

Naturally occurring L-group ordinary chondritic meteorite material considered as a potential experimental feed, not a mineral species, secondary waste or established commercial ore. The curated experiment used fragments identified by its authors as Northwest Africa 869, an L3-6 regolith breccia, containing heterogeneous silicate, sulfide and metal phases. These Earth-collected fragments were transported to the International Space Station; the study did not mine an asteroid in situ. Results apply to the tested specimens and conditions, not every L-chondrite. Constituent metals do not confer a criticality designation on this resource.

Microbial & Biochemical Mechanisms (1)

Culture-associated elemental mobilization in flight and ground assays

bioleaching Microbial

Associated Organisms: Sphingomonas desiccabilis (NCBITaxon:429134), Penicillium simplicissimum (NCBITaxon:69488)

Living Sphingomonas desiccabilis CP1D and Penicillium simplicissimum DSM 1078, tested separately and together, colonized meteorite fragments and were associated with element-dependent changes in liquid-fraction metal measurements. Fungal arms on the ISS had higher mean platinum-group element extraction than sterile controls, but the within-ISS PGE comparisons against those controls were not statistically significant. This is a controlled small-scale flight experiment with qualified mobilization observations, not isolated-metal recovery or demonstrated industrial or asteroid-mining deployment.

Experimental Context & Analytical Limits:
Methods pp.9-12 used approximately 1-3.5 mm fragments, 0.79 +/- 0.14 g per sample (mean +/- standard deviation), sterilized at 250 degrees C for four hours. Cultures were air-dried onto the fragments before rehydration with 5 mL of half-strength R2A, initially pH 7.2. Separate bacterial, fungal, mixed-culture and uninoculated arms underwent 19 days of incubation in BioMining Reactors: logged 19.5 degrees C on the ISS and nominal 20 degrees C in the later Earth controls. The analytical comparison used three samples per ISS arm, four per biological Earth arm and six non-biological Earth samples. Ground and flight samples differed in preparation dates, handling and storage, so their contrast does not isolate gravity from every flight-associated factor. Each chamber received 1 mL RNAlater at termination; the recovered liquid fraction was acidified to 4% v/v nitric acid for ICP-MS. Fungal liquids were first sonicated and passed through cotton to homogenize mycelia; the method does not establish a membrane-filtered dissolved fraction or a separate biomass-metal mass balance. Medium and fixative were also analyzed. Bulk-rock digestion supplied the denominator for reported percent extraction. Heterogeneity, small sample numbers and downstream processing limit generalization. No product-isolation step was tested.
Curated Evidence Points:
Figures 1-3 and Methods establish the actual meteorite substrate, named culture arms, sterile controls and microbial surface association. Figure 5B reports mean fungal ISS extraction of 19.29% of bulk-rock ruthenium, 11.91% of palladium and 0.29% of platinum. These are author-reported fractions of the element inventory, not percent improvement, purified yields or kinetic rates.
Tables 2-3 support the numerical observations but limit enhancement claims. Within the ISS, all biological-versus-uninoculated raw PGE concentration comparisons have Tukey p-values above 0.05. Fungal palladium is 549.34% of the sterile-control mean, not a 549.34% increase; its large reported uncertainty accompanies the small experiment. Ground palladium is lower in all biological arms than in sterile controls. The consortium does not consistently improve on the fungus alone. A higher mean, normalization to background or a selected fold-change threshold is not proof of a universal effect.
Supplementary Note 1 and Table 8 report contamination concerns in ground fungal samples, including Bacillales sequence assignments; its timing and contribution were not experimentally resolved. The authors could not repeat the experiment with identical meteorite material. Their interpretation that ISS contamination arose during plating is not independent proof of complete original-sample purity. Comparisons involving ground fungal cultures retain this limitation. Note 1 and Table 9 also state that RNAlater affected final pH, preventing inference of the pH trajectory during growth.
Metabolomic differences and proposed carboxylic-acid contributions provide mechanistic hypotheses. They do not isolate the causal contribution of a particular acid, enzyme or consortium member to the accepted elemental measurements. Metal signals in recovered liquid are not a direct assay of mineral-specific dissolution.

Sources & References

  1. santomartino2026: Santomartino et al. (2026). Microbial biomining from asteroidal material onboard the international space station. npj Microgravity 12:23. DOI 10.1038/s41526-026-00567-3. Final 15-page publisher PDF inspected, especially Figures 1-5, Tables 1-2 and Methods pp.9-12.
    https://www.nature.com/articles/s41526-026-00567-3 (accessed 2026-10-16)
  2. santomartino2026_si: Santomartino et al. (2026), 32-page supplementary information. Note 1 pp.2-4, Tables 2-3 pp.18-19, Table 8 and Table 9 constrain statistical, contamination and post-fixation pH interpretations.
    https://media.springernature.com/original/springer-static/esm/art%3A10.1038%2Fs41526-026-00567-3/MediaObjects/41526_2026_567_MOESM1_ESM.pdf (accessed 2026-10-16)
  3. ncbi_desiccabilis: NCBI Taxonomy 429134, Sphingomonas desiccabilis, species. The species identifier does not itself identify the experimental CP1D culture.
    https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?id=429134 (accessed 2026-10-16)
  4. ncbi_simplicissimum: NCBI Taxonomy 69488, Penicillium simplicissimum, species. The study's experimental designation DSM 1078 comes from its Methods, not this species identifier.
    https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?id=69488 (accessed 2026-10-16)

Curation History

Timestamp Curator Action Summary
2026-10-16T05:14:45.743218Z codex (GPT-6; codex) CREATE Added a natural L-chondrite feed record with qualified flight and ground microbial mobilization evidence.

Record source: data/records/l-chondrite-meteorite.yaml