Fluorine element Critical Material
The element F, distinct from fluoride anion, molecular fluorine, individual organofluorine compounds, fluorite mineral and the fluorspar commodity. Australia's explicitly named Fluorine entry is mapped to the element; its comparative footnote about US and EU fluorspar does not establish elemental-fluorine criticality in those jurisdictions.
Identifiers & Classification
| System | Identifier | Label |
|---|---|---|
| CHEBI |
CHEBI:24061
|
fluorine atom |
Criticality Designations
| Jurisdiction | List Name | Edition / Document | Classification | Source |
|---|---|---|---|---|
| Australia | Department of Industry, Science and Resources Critical Minerals List | 20 February 2024 update; Table 1 | critical |
australia_2024
|
Microbial & Biochemical Mechanisms (2)
Enantioselective hydrolytic defluorination by recombinant Pseudomonas
other
Microbial
Associated Organisms:
Pseudomonas putida (NCBITaxon:303)
Pseudomonas putida ATCC 12633 engineered to constitutively express a Delftia acidovorans strain B defluorinase grew on two model fluorinated acids while releasing inorganic fluoride. Approximately half of the fluorine in each racemic substrate was released, consistent with preferential conversion of its S enantiomer. This is hydrolytic C-F bond cleavage, not fluorine reduction, universal PFAS degradation or isolation of a usable fluorine product.
Experimental Context & Analytical Limits:
Laboratory recombinant culture grown with 20 mM racemic alpha-fluorophenylacetic acid or 2-fluoropropionic acid as sole carbon source in mineral salts basal medium. The medium had 40 mM sodium/potassium phosphate buffer at pH 6.8, ammonium chloride 1 g/L, trace metals and vitamins, and 50 micrograms/mL kanamycin for the recombinant strain. General flask methods specify 20 mL in 125 mL baffled flasks, 200 rpm, initial OD600 0.05-0.1 and growth at 28 or 30 degrees C; the main methods do not assign one of those two temperatures unambiguously to each flask result. The separate 96-well lag assay specifies 30 degrees C. Inocula were washed once and pregrown on mandelic acid or D-lactic acid, respectively. Fluoride was measured with an ion-selective electrode calibrated with NaF; OD600 and colony counts assessed growth and viability. Species taxonomy is grounded separately from the ATCC strain and its laboratory expression construct. The introduction's isolated 12663 spelling conflicts with 12633 in Methods, Results and the culture authority; this record follows the latter. No fluorine-containing mineral, mixed environmental waste or industrial process was tested in the curated assays.
Laboratory recombinant culture grown with 20 mM racemic alpha-fluorophenylacetic acid or 2-fluoropropionic acid as sole carbon source in mineral salts basal medium. The medium had 40 mM sodium/potassium phosphate buffer at pH 6.8, ammonium chloride 1 g/L, trace metals and vitamins, and 50 micrograms/mL kanamycin for the recombinant strain. General flask methods specify 20 mL in 125 mL baffled flasks, 200 rpm, initial OD600 0.05-0.1 and growth at 28 or 30 degrees C; the main methods do not assign one of those two temperatures unambiguously to each flask result. The separate 96-well lag assay specifies 30 degrees C. Inocula were washed once and pregrown on mandelic acid or D-lactic acid, respectively. Fluoride was measured with an ion-selective electrode calibrated with NaF; OD600 and colony counts assessed growth and viability. Species taxonomy is grounded separately from the ATCC strain and its laboratory expression construct. The introduction's isolated 12663 spelling conflicts with 12633 in Methods, Results and the culture authority; this record follows the latter. No fluorine-containing mineral, mixed environmental waste or industrial process was tested in the curated assays.
Curated Evidence Points:
Support
Source:
dodge_2024
Figure 2 and Table 2 show growth-associated fluoride release. Table 2 reports 9.9 +/- 0.1 mM fluoride from 20 mM racemic alpha-fluorophenylacetic acid and 9.9 +/- 0.2 mM from 20 mM racemic 2-fluoropropionic acid, with times to maximal OD600 of 29 and 78 h, respectively. Values are means and standard deviations of three biological replicates; the authors report similar results in one independent repetition. The denominator is total racemic substrate: this is about half of its fluorine, not complete conversion or a recovered-product yield. Wild-type ATCC 12633 did not grow on these test acids in the stated tests.
Support
Source:
dodge_2024
Purified-enzyme assays include substrate solutions without enzyme as spontaneous-release controls. Figure 3 and stereochemistry methods distinguish two experiments: polarimetry of residual alpha-fluorophenylacetic acid from a growing culture supported retention of the R enantiomer, whereas stereospecific lactate dehydrogenases identified D-lactate after purified-enzyme treatment of racemic 2-fluoropropionic acid. These observations support selective hydrolysis. The modeled active-site attack is an interpretation, not a new crystal structure or mutational proof.
Partial
Source:
dodge_2024
Table 1 reports activities below 0.01 micromole/min/mg for tested difluorinated substrates and a fluoroolefin under its enzyme-assay conditions; these limits are not zero or proof about all PFAS. Table 2 shows lower final OD600 on fluorinated substrates than on the corresponding nonfluorinated products, and Figure 2F shows an initial colony-count decline before recovery. CrcB involvement is inferred from genomic comparison and other-strain literature, not a transporter knockout in this recombinant strain. Wild-type nongrowth is not itself a quantitative abiotic fluoride-release control for the flask cultures. Intracellular fluoride concentrations and an isolated fluoride product were not measured in these assays.
Conditional fungal release of fluoride from precipitated calcium fluoride
bioleaching
Microbial
Source-labeled fungal isolates produced more electrode-detectable fluoride in filtered liquid culture than uninoculated medium containing supplier-precipitated calcium fluoride. This is a laboratory observation of net fluoride mobilization from an inorganic reagent, not elemental fluorine production, authenticated natural-fluorite dissolution or isolated-product recovery. The paper's separate autoclaved-soil experiment showed no positive calcium-fluoride-associated release for its two tested isolates. The chemical cause of the liquid response was not isolated; an increase in culture pH does not demonstrate acid leaching.
Experimental Context & Analytical Limits:
Wainwright and Supharungsun used fungi isolated from fluoride-polluted soils and identified by source labels, without accessioned strain authentication. The CaF2 feed is explicitly precipitated B.D.H. reagent; its natural origin, mineral phase purity and particle characteristics were not established. The liquid assay used modified Czapek-Dox medium, mycelial-disc inocula, 25 degrees C, reciprocal shaking at 100 throws/min and a 14-day endpoint. Table 2 gives separate CaF2-loading, carbon-source and initial-buffer-pH assays for Penicillium sp. I and source-labeled Fusarium culmorum. The general Methods wording specifies 100 mg/cm3 CaF2 (10% w/v), but Table 2 reports no growth at 5% and 10%; this unresolved conflict prevents assigning that general dose to every positive assay. Table 2's carbon-source heading specifies 0.3% w/v, its default glucose footnote 0.1% w/v, and Methods mentions 1 g/L malt extract. Results also calls a carbon-source culture F. solani where Table 2 labels F. culmorum. These assay and organism-label conflicts are retained rather than reconciled by inference. Filtered broth and soil-water extracts were mixed 1:1 with TISAB and measured using a fluoride-specific electrode. Liquid table results are excess over uninoculated controls, not absolute dissolved concentrations or feed recovery fractions. No phase analysis, isolated fluoride product or industrial test accompanies the experiment.
Wainwright and Supharungsun used fungi isolated from fluoride-polluted soils and identified by source labels, without accessioned strain authentication. The CaF2 feed is explicitly precipitated B.D.H. reagent; its natural origin, mineral phase purity and particle characteristics were not established. The liquid assay used modified Czapek-Dox medium, mycelial-disc inocula, 25 degrees C, reciprocal shaking at 100 throws/min and a 14-day endpoint. Table 2 gives separate CaF2-loading, carbon-source and initial-buffer-pH assays for Penicillium sp. I and source-labeled Fusarium culmorum. The general Methods wording specifies 100 mg/cm3 CaF2 (10% w/v), but Table 2 reports no growth at 5% and 10%; this unresolved conflict prevents assigning that general dose to every positive assay. Table 2's carbon-source heading specifies 0.3% w/v, its default glucose footnote 0.1% w/v, and Methods mentions 1 g/L malt extract. Results also calls a carbon-source culture F. solani where Table 2 labels F. culmorum. These assay and organism-label conflicts are retained rather than reconciled by inference. Filtered broth and soil-water extracts were mixed 1:1 with TISAB and measured using a fluoride-specific electrode. Liquid table results are excess over uninoculated controls, not absolute dissolved concentrations or feed recovery fractions. No phase analysis, isolated fluoride product or industrial test accompanies the experiment.
Curated Evidence Points:
Support
Source:
wainwright_1984
Original pages 289-291, Methods and Tables 1-2, support a conditional inoculation-associated liquid response. Table 2's explicitly labeled 2% w/v CaF2 arm reports net fluoride of 28.0 +/- 1.6 and 32.7 +/- 1.0 micrograms/cm3 culture filtrate for source-labeled F. culmorum and Penicillium sp. I, respectively. The paper identifies means of triplicates with standard deviations; these are control- subtracted endpoints, not percent dissolution or recovered yield. Both cultures show no growth at the separately tabulated 5% and 10% loadings and at buffer pH 2.6 and 3.6. Loading, medium and identity conflicts in the source limit comparisons between tables.
Partial
Source:
wainwright_1984
Pages 290-292, soil Methods and Table 4, use a distinct assay: 5 g autoclaved unpolluted soil, glucose amendment, 50 mg CaF2 per gram soil, spores of source-labeled F. merismoides or Penicillium sp. I, incubation at 25 degrees C and water-extract fluoride through seven weeks. Neither inoculated CaF2 arm exceeds the corresponding uninoculated control at the reported times. This is evidence against transferring the liquid response to that soil system; it does not prove that no microscopic dissolution occurred. The authors propose adsorption as a limitation of fluoride detection in soil extracts. Cryolite gave a separate small positive Penicillium response and must not be substituted for the CaF2 result or an authenticated mineral-specific outcome.
Partial
Source:
wainwright_1984
The comparison with uninoculated controls supports net solution mobilization under the reported assay conditions. It does not distinguish growth-associated pH change, ligand chemistry, adsorption/desorption or mineral-surface processes: matched-pH, metabolite-only, killed-biomass and solid-phase comparisons are not reported. The historical isolate labels do not establish modern strain identity. The proposed use of fungi on industrial raw-material piles is prospective discussion, not demonstrated deployment.
Sources & References
-
chebi_fluorine: ChEBI:24061 - fluorine atom; formula F, charge 0
https://www.ebi.ac.uk/chebi/CHEBI:24061 (accessed 2026-10-11) -
australia_2024: Australian Department of Industry, Science and Resources. Australia's Critical Minerals List and Strategic Materials List, update of 20 February 2024; Table 1, Fluorine row and footnote 13.
https://www.industry.gov.au/publications/australias-critical-minerals-list-and-strategic-materials-list (accessed 2026-10-11) -
dodge_2024: Dodge, Thoma, O'Connor and Wackett. Recombinant Pseudomonas growing on non-natural fluorinated substrates shows stress but overall tolerance to cytoplasmically released fluoride anion. mBio 15(1):e02785-23, 2024 issue; online 8 December 2023. DOI 10.1128/mbio.02785-23; PMC10790756. Methods, Results, Tables 1-2, Figures 2-3 and accompanying supplemental DOCX, Figures S1-S7 and Tables S1-S2.
https://doi.org/10.1128/mbio.02785-23 (accessed 2026-10-11) -
ncbi_putida: NCBI Taxonomy 303 - Pseudomonas putida; species-level entry
https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?id=303&mode=Info (accessed 2026-10-11) -
atcc_12633: ATCC 12633 - Pseudomonas putida culture catalog entry
https://www.atcc.org/products/12633 (accessed 2026-10-11) -
wainwright_1984: Wainwright and Supharungsun. Release by fungi of F- from insoluble fluorides. Transactions of the British Mycological Society 82(2):289-292 (1984). DOI 10.1016/S0007-1536(84)80071-6. Complete original pages 289-292, including Methods and Tables 1-4; journal-authorized Cyberliber page scans inspected.
https://doi.org/10.1016/S0007-1536(84)80071-6 (accessed 2026-10-13)
Curation History
| Timestamp | Curator | Action | Summary |
|---|---|---|---|
2026-10-11T07:25:31Z |
Codex (GPT-6; Codex) | CREATE | Created elemental fluorine identity, Australian2024 criticality and enantioselective recombinant-culture defluorination evidence; retained total-racemate denominator, stress and mechanistic limits. |
2026-10-13T02:11:00Z |
Codex (GPT-6; Codex) | EDIT | Added a separate 1984 fungal net-fluoride-mobilization assay using precipitated CaF2, with original Tables 1-4, loading and isolate-label conflicts, control-subtracted endpoints and a soil null result. Kept natural fluorite, elemental fluorine, recovery and deployment claims distinct; earlier scientific fields are unchanged. |
Record source: data/records/fluorine.yaml