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Selenium element Critical Material

Selenium (Se), chemical element with atomic number 34. The experimental substrate is soluble selenite, distinct from the element identifier, a selenium mineral, or a secondary resource. Australia's dated selenium material designation is mapped to this element without extending it to salts.

Identifiers & Classification

System Identifier Label
CHEBI CHEBI:27568 selenium atom

Criticality Designations

Jurisdiction List Name Edition / Document Classification Source
Australia Department of Industry, Science and Resources Critical Minerals List 20 February 2024 revision critical australia_2024

Microbial & Biochemical Mechanisms (1)

Non-growing MR-1 selenite reduction with conditional FccA and CymA involvement

redox transformation Microbial

Associated Organisms: Shewanella oneidensis MR-1 (NCBITaxon:211586)

Washed Shewanella oneidensis MR-1 cells transformed selenite to selenium-associated particles, with XPS supporting elemental Se in the analyzed cell fraction. Gene-deletion phenotypes support FccA and CymA involvement under the tested conditions; they do not prove an exclusive pathway or direct catalysis by purified FccA.

Experimental Context & Analytical Limits:
Laboratory cells grown in LB at 30 degrees C were washed twice and added at OD600 1.0 to 40 mL anaerobic mineral medium under nitrogen, with 0.5 mM selenite and 20 mM lactate at 30 degrees C. The medium contains HEPES/NaOH but the paper does not state a measured pH. Fumarate at 20 mM was added only in the separate competition assay. The authors report no growth and declining protein-based biomass. Kinetic rates refer to the initial 12 h; XPS sampled washed, lyophilized cells after 48 h. These are laboratory transformations, not demonstrated purified-product recovery or industrial deployment.
Curated Evidence Points:
Support Source: li_2014
Figure 2 and Results report initial selenite-depletion rates of 0.54 +/- 0.13 micromol/h for delta-fccA and 1.35 +/- 0.05 for WT; the caption specifies standard errors of triplicate cultures. Figure 4 preserves substantial later residual reduction in delta-cymA. Thus reduced rates support involvement, not absolute necessity. No complementation or purified-FccA assay is reported.
Support Source: li_2014
Figure 5 shows predominantly intracellular and smaller surface particles. EDX establishes elemental composition; the 48 h Se 3d XPS peak supports the Se(0) assignment. Neither proves exclusive periplasmic localization or a phase-pure isolated product. Supernatant selenite was assayed by acid/ascorbate colorimetry; Table 1 provides a separate digestion/ICP-AES selenium balance, not an isolated recovery yield.
Figure S1 caption identifies autoclaved cells as the adsorption comparison; main Results report negligible adsorption. Figure S2 caption and S4 describe a BSA-equivalent Micro BCA protein assay for biomass, rather than a viable-cell count. Supplement captions and methods were read; embedded graph pixels were not rendered, so no supplementary numeric points are transcribed.
In a different LB growth context, the paper describes extracellular or cell-attached selenium deposits (Figure 1, 2 mM selenite) and reports that a cymA-deletion mutant still reduces selenite (data not shown). These observations limit universal localization and pathway claims. They are not a matched quantitative refutation of Li's rate defect. The older EDX assignment alone does not resolve selenium oxidation state.

Sources & References

  1. chebi_selenium: ChEBI:27568 - selenium atom
    https://www.ebi.ac.uk/chebi/CHEBI:27568 (accessed 2026-10-11)
  2. australia_2024: Australian Government, Department of Industry, Science and Resources. Australia's Critical Minerals List, revision 20 February 2024. Table 1, Selenium row; Australia's own designation.
    https://www.industry.gov.au/publications/australias-critical-minerals-list-and-strategic-materials-list (accessed 2026-10-11)
  3. li_2014: Li et al. (2014). Selenite reduction by Shewanella oneidensis MR-1 is mediated by fumarate reductase in periplasm. Scientific Reports 4:3735. DOI 10.1038/srep03735; PMC3894562; Methods, Figures 2, 4, 5 and Table 1.
    https://doi.org/10.1038/srep03735 (accessed 2026-10-11)
  4. li_2014_supplement: Li et al. (2014), supporting information, srep03735-s1.doc. Figures S1-S2 captions and S4 Methods: autoclaved-cell comparison and protein-based biomass assay.
    https://media.springernature.com/original/springer-static/esm/art%3A10.1038%2Fsrep03735/MediaObjects/41598_2014_BFsrep03735_MOESM1_ESM.doc (accessed 2026-10-11)
  5. klonowska_2005: Klonowska, Heulin and Vermeglio (2005). Selenite and Tellurite Reduction by Shewanella oneidensis. Applied and Environmental Microbiology 71:5607-5609. DOI 10.1128/AEM.71.9.5607-5609.2005. Results and Figure 1 caption; different growth-medium context.
    https://doi.org/10.1128/AEM.71.9.5607-5609.2005 (accessed 2026-10-11)
  6. ncbi_mr1: NCBI Taxonomy 211586 - Shewanella oneidensis MR-1, no-rank strain entry
    https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?id=211586&mode=Info (accessed 2026-10-11)

Curation History

Timestamp Curator Action Summary
2026-10-11T04:38:08Z Codex (GPT-6; Codex) CREATE Created selenium identity, Australia's dated designation and laboratory MR-1 transformation evidence; retained conditional mutant effects, localization differences, assay and supplementary-rendering limits.

Record source: data/records/selenium.yaml