Molybdenum element Critical Material
The element Mo, distinct from molybdate ions, experimental sodium molybdate, molybdenum-blue products, molybdenite and other Mo-bearing resources. The Canadian designation is the named molybdenum material in its 2024 list; it does not assign criticality to every compound or ore. A laboratory DRY1 culture study supports molybdenum-blue formation consistent with molybdate transformation, without an isolated-metal recovery yield or a chemically resolved product phase.
Identifiers & Classification
| System | Identifier | Label |
|---|---|---|
| CHEBI |
CHEBI:28685
|
molybdenum atom |
Criticality Designations
| Jurisdiction | List Name | Edition / Document | Classification | Source |
|---|---|---|---|---|
| Canada | Canada's Critical Minerals List | 2024 update; released 10 June 2024; 34 materials | critical |
canada2024
|
Microbial & Biochemical Mechanisms (1)
DRY1 culture-associated molybdenum-blue formation
redox transformation
Microbial
Associated Organisms:
gamma proteobacterium DR.Y1 (NCBITaxon:351651)
Living DRY1 cultures produced a blue optical signal from a sodium molybdate medium, consistent with conversion to reduced phosphomolybdate-like material. The product spectrum and activity retained in partially purified cell extracts support a biological contribution, but neither identify a homogeneous reductase nor directly establish the product's oxidation-state distribution or crystalline phase. This is a laboratory transformation assay, not quantified removal of total Mo or production of purified molybdenum.
Experimental Context & Analytical Limits:
DRY1 was isolated from Antarctic soil collected near Jubany Station during 2002-2003. The paper tentatively assigns it to Pseudomonas using partial 16S phylogeny and Biolog tests, explicitly without species-level resolution. Its deposited sequence DQ226202.1 currently identifies gamma proteobacterium DR.Y1 with taxon 351651; that accession-linked label is retained rather than promoting the tentative genus assignment to an established species. Section 2.1 describes 50 mL cultures held statically at 10 degrees C for 72 h in pH 7 low-phosphate medium containing 0.242% w/v sodium molybdate dihydrate, 1% glucose, 0.3% ammonium sulfate, 0.05% yeast extract and 2.8 mM phosphate. Centrifuged supernatant was scanned at 400-980 nm with fresh medium as the optical baseline. Figure 8 separately shows spectra after 28-72 h at 20 degrees C. The optimization methods specify 48 h, whereas Figures 2-7 specify 72 h; these arms are not merged into a single optimum protocol. The study describes cells coprecipitating with blue material, but does not provide a total-Mo mass balance, recovered-solid yield or a matched incubated uninoculated/heat-killed culture comparison. Fresh medium used for baseline correction is not that incubation control.
DRY1 was isolated from Antarctic soil collected near Jubany Station during 2002-2003. The paper tentatively assigns it to Pseudomonas using partial 16S phylogeny and Biolog tests, explicitly without species-level resolution. Its deposited sequence DQ226202.1 currently identifies gamma proteobacterium DR.Y1 with taxon 351651; that accession-linked label is retained rather than promoting the tentative genus assignment to an established species. Section 2.1 describes 50 mL cultures held statically at 10 degrees C for 72 h in pH 7 low-phosphate medium containing 0.242% w/v sodium molybdate dihydrate, 1% glucose, 0.3% ammonium sulfate, 0.05% yeast extract and 2.8 mM phosphate. Centrifuged supernatant was scanned at 400-980 nm with fresh medium as the optical baseline. Figure 8 separately shows spectra after 28-72 h at 20 degrees C. The optimization methods specify 48 h, whereas Figures 2-7 specify 72 h; these arms are not merged into a single optimum protocol. The study describes cells coprecipitating with blue material, but does not provide a total-Mo mass balance, recovered-solid yield or a matched incubated uninoculated/heat-killed culture comparison. Fresh medium used for baseline correction is not that incubation control.
Curated Evidence Points:
Support
Source:
ahmad2013
Sections 2.1-2.2 and 3.2-3.6, with Figures 2-8, support the culture-associated blue response and its dependence on culture conditions. The spectrum peaks at 865 nm with a shoulder at 710 nm; Figure 8 records increasing blue intensity over incubation. These optical results support the narrowly described transformation but are not an elemental concentration assay or recovery percentage. Section 3.5 and Figure 7 also report strong inhibition at high phosphate, limiting transfer to other medium compositions.
Partial
Source:
ahmad2013
Sections 2.5-2.7 and 3.8-3.9 and Table 1 report Mo-blue-forming activity in cell-extract fractions assayed with NADH and 12-molybdophosphate, a different acceptor from free molybdate in the culture medium. Purification reached about fivefold enrichment with multiple native-PAGE bands and low final yield. This supports a cell-derived catalytic contribution without establishing a single enzyme identity or excluding chemical reduction in the assay. The dialysis experiment in Sections 2.9 and 3.7 favors blue material on the cell-containing side, but the reported 95%/5% division does not agree arithmetically with its 13.775/1.225 micromole values; no exact partition or conversion efficiency is accepted here.
Partial
Source:
ahmad2013
Table 2 reports little inhibition by the tested respiratory inhibitors, while Section 2.8 and Table 2 assign conflicting doses to individual inhibitors. The negative inhibitor responses do not establish a unique electron-transfer pathway. Section 4 proposes a phosphomolybdate intermediate from spectral similarity and explicitly calls for structural identification. No direct Mo-valence spectroscopy or crystalline-phase identification is reported; molybdenum-blue absorbance must not be equated with quantitative Mo(VI) detoxification, an identified metal phase or efficient recovery.
Sources & References
-
chebi_molybdenum: ChEBI CHEBI:28685 - molybdenum atom; formula Mo, net charge 0
https://www.ebi.ac.uk/chebi/CHEBI:28685 (accessed 2026-10-11) -
canada2024: Natural Resources Canada. Critical minerals: an opportunity for Canada; complete 34-material list, 2024 update, molybdenum entry.
https://www.canada.ca/en/campaign/critical-minerals-in-canada/critical-minerals-an-opportunity-for-canada.html (accessed 2026-10-11) -
canada2024_release: Natural Resources Canada (10 June 2024). Government of Canada Releases Updated Critical Minerals List; release date and 34-material scope.
https://www.canada.ca/en/natural-resources-canada/news/2024/06/government-of-canada-releases-updated-critical-minerals-list.html (accessed 2026-10-11) -
ahmad2013: Ahmad et al. (2013). Molybdate Reduction to Molybdenum Blue by an Antarctic Bacterium. BioMed Research International 2013:871941; Sections 2-4, Figures 2-8 and Tables 1-3.
https://doi.org/10.1155/2013/871941 (accessed 2026-10-11) -
ncbi_dry1: NCBI Taxonomy 351651 - gamma proteobacterium DR.Y1
https://eutils.ncbi.nlm.nih.gov/entrez/eutils/efetch.fcgi?db=taxonomy&id=351651&retmode=xml (accessed 2026-10-11) -
genbank_dry1: GenBank DQ226202.1 - gamma proteobacterium DR.Y1 isolate DR.Y1, partial 16S ribosomal RNA gene; 1452 bases, taxon 351651.
https://www.ncbi.nlm.nih.gov/nuccore/DQ226202.1 (accessed 2026-10-11)
Curation History
| Timestamp | Curator | Action | Summary |
|---|---|---|---|
2026-10-11T05:40:13Z |
Codex (GPT-6; Codex) | CREATE | Added verified elemental identity, dated Canadian criticality and DRY1 molybdenum-blue evidence, retaining accession-linked taxonomy, source inconsistencies and limits on product identity and recovery claims. |
Record source: data/records/molybdenum.yaml