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Thulium element Critical Material

Thulium is the element Tm, represented by its neutral-atom identity and distinct from Tm(III) chloride solutions, mineral hosts and rare-earth commodities. It is named in the United States Final 2025 List of Critical Minerals. Prepared Bacillus subtilis cell powders provide laboratory evidence for thulium biosorption and subsequent acidic elution, without an isolated pure-metal yield or demonstrated industrial process.

Identifiers & Classification

System Identifier Label
CHEBI CHEBI:33380 thulium atom

Criticality Designations

Jurisdiction List Name Edition / Document Classification Source
United States Final 2025 List of Critical Minerals 2025; Federal Register notice of 7 November 2025 critical usgs_2025

Microbial & Biochemical Mechanisms (1)

Thulium biosorption by boiled and freeze-dried Bacillus subtilis cell powders

biosorption Microbial

Associated Organisms: Bacillus subtilis subsp. subtilis str. 168 (NCBITaxon:224308)

Inactive cell powders from B. subtilis 168 and its LTA-defective RY1604 derivative removed dissolved thulium from defined chloride solutions. Table 3 entry 4 reports 90% and 74% removal for WT and LTA-defective powders, respectively, at 20 micrograms Tm/mL. Removal persisted in the defective preparation, so the comparison does not establish an exclusive lipoteichoic-acid-mediated route or quantify its contribution. Nitric acid eluted adsorbed rare-earth ions in a separate recovery step; the study did not establish a purified thulium-metal product.

Experimental Context & Analytical Limits:
The accepted manuscript describes RY1604 as deletions of yfnI, yqgS and yvgJ combined with inducible ltaS, prepared after IPTG removal; Table 1 uses yvyJ where the construction methods use yvgJ. Biomass was boiled for 20 minutes, washed, freeze-dried, crushed and sieved to 53–100 micrometres. Assays used 20 mg powder in 20 mL metal solution at pH 3, 25 degrees C, mixed at 10 rpm for 30 minutes. Filter paper with nominal 7-micrometre retention and subsequent centrifugation separated solids before ICP atomic-emission spectrometry. Filter-associated adsorption was reported below 10%, but a blank-correction calculation and replicated uncertainty for Table 3 were not specified. WT-versus-mutant comparison tests these prepared biomasses, not growing-cell metabolism. No complemented-mutant adsorption assay was reported. The fitted saturation capacities are not accepted as measured capacities here: the deposited manuscript refers to Table 4 but does not include that table. The experiments used laboratory synthetic solutions, not ore or field water.
Curated Evidence Points:
Preparation and Adsorption test methods (PDF pp. 7–9), Table 3 (PDF p. 21) and Figure 2 (PDF p. 23) support rapid Tm solution depletion by both powders. The Table 3 concentration header is micrograms/mL in the rendered PDF, despite erroneous extracted text. Entry 6 reports lower fractional removal at 100 micrograms/mL (35% WT; 29% defective), so the 20-micrograms/mL outcome is not a loading-independent performance guarantee.
The results on PDF p. 11 describe two 20-mL elutions with 2.7 M nitric acid and greater than 94% recovery of adsorbed rare-earth ions for both powders. This is stated across La, Eu and Tm, with no element-specific elution table or uncertainty; it is not greater than 94% recovery of initial thulium feed. Morphology, residual binding in RY1604 and the unquantified LTA/WTA abundances prevent assigning an exclusive ligand mechanism. Both Langmuir and Freundlich fits were acceptable, and the authors explicitly say these fits do not distinguish the adsorption mechanism. No direct Tm speciation or site-resolved spectroscopy is supplied.
Context_only Source: moriwaki_2013
Publisher metadata and abstract confirm the publication identity and broad WT/defective comparison. The full scientific assessment uses the openly deposited accepted manuscript; the subscription version and its referenced capacity table were not accessed.

Sources & References

  1. chebi_thulium: ChEBI CHEBI:33380, thulium atom; neutral Tm entity and lanthanoid relation
    https://www.ebi.ac.uk/chebi/CHEBI:33380 (accessed 2026-10-11)
  2. usgs_2025: US Geological Survey (2025). Final 2025 List of Critical Minerals, Federal Register 90, 50494–50497, 7 November; named thulium entry
    https://www.govinfo.gov/content/pkg/FR-2025-11-07/html/2025-19813.htm (accessed 2026-10-11)
  3. moriwaki_2013: Moriwaki, Koide, Yoshikawa, Warabino and Yamamoto (2013; online 2012). Adsorption of rare earth ions onto the cell walls of wild-type and lipoteichoic acid-defective strains of Bacillus subtilis. Applied Microbiology and Biotechnology 97, 3721–3728
    https://doi.org/10.1007/s00253-012-4200-3 (accessed 2026-10-11)
  4. moriwaki_accepted_manuscript: Moriwaki et al., Shinshu University deposited accepted manuscript; 24 PDF pages, methods pp. 5–9, results/discussion pp. 10–14, Tables 1–3 and Figures 1–3
    https://soar-ir.repo.nii.ac.jp/records/13337 (accessed 2026-10-11)
  5. ncbi_bsubtilis_168: NCBI Taxonomy 224308, Bacillus subtilis subsp. subtilis str. 168; parental strain context, not a separate identifier for RY1604
    https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?id=224308 (accessed 2026-10-11)

Curation History

Timestamp Curator Action Summary
2026-10-11T07:54:11Z Codex (GPT-6; Codex) CREATE Added thulium identity and US 2025 designation with inactive bacterial-powder biosorption; preserved mutant, loading, filter-background and elution limits.
2026-10-11T08:02:40Z Codex (GPT-6; Codex) EDIT Narrowed LTA causality after independent finding F1 and issue 45; residual adsorption does not establish that LTA is unnecessary when residual LTA is unmeasured.

Record source: data/records/thulium.yaml