Gold element
Gold (Au), represented by its neutral-atom identity. The laboratory Au(III)-chloride solutions and source-assigned cell-associated particles below are experimental forms of this element, not separate ore or waste-feed identities. No criticality-list designation is asserted here.
Identifiers & Classification
| System | Identifier | Label |
|---|---|---|
| CHEBI |
CHEBI:29287
|
gold atom |
Microbial & Biochemical Mechanisms (1)
Stock-dependent culture-associated formation of source-assigned gold nanoparticles
biomineralization
Microbial
Associated Organisms:
Cupriavidus metallidurans (NCBITaxon:119219)
Cupriavidus metallidurans AE104 cells exposed to an aqua-regia-prepared Au(III) solution contained particles interpreted by the authors as periplasmic gold nanoparticles. The commercial Au(III) stock instead produced damaged cells or no visible nanoparticles in the reported microscopy series. This laboratory comparison supports a preparation-dependent outcome, not universal reduction of every gold complex or an isolated-product recovery yield.
Experimental Context & Analytical Limits:
AE104 is the plasmid-free derivative of CH34; the species identifier does not identify this derivative. Cells were cultivated aerobically in Tris-buffered mineral salts medium with 2 g/L sodium gluconate at 30 degrees C. The TEM protocol used two precultures at 200 rpm, a 66-fold dilution into fresh medium, and addition of Au(III)-chloride after reaching 180-200 Klett units. Incubation after addition was at 100 rpm and 30 degrees C. Figure 2A reports 50 micromolar of the previously used, aqua-regia-prepared stock for 72 h. Commercial HAu(III)Cl4 was Sigma-Aldrich TraceCERT, supplied as 1 g/L Au in hydrochloric acid; Figure 2B-D report 50 micromolar for 70 h, 15 micromolar for 21 h, and 50 micromolar for 30 min. The general methods describe 72 h and additional exposure/recovery experiments; their timings are not substituted for the labeled panels. Samples were fixed with glutaraldehyde and osmium tetroxide, ethanol-dehydrated, uranyl-acetate-stained, resin-embedded and sectioned at 80 nm. Exact final medium pH and a molecular analysis of the two stock solutions are not reported for this microscopy comparison.
AE104 is the plasmid-free derivative of CH34; the species identifier does not identify this derivative. Cells were cultivated aerobically in Tris-buffered mineral salts medium with 2 g/L sodium gluconate at 30 degrees C. The TEM protocol used two precultures at 200 rpm, a 66-fold dilution into fresh medium, and addition of Au(III)-chloride after reaching 180-200 Klett units. Incubation after addition was at 100 rpm and 30 degrees C. Figure 2A reports 50 micromolar of the previously used, aqua-regia-prepared stock for 72 h. Commercial HAu(III)Cl4 was Sigma-Aldrich TraceCERT, supplied as 1 g/L Au in hydrochloric acid; Figure 2B-D report 50 micromolar for 70 h, 15 micromolar for 21 h, and 50 micromolar for 30 min. The general methods describe 72 h and additional exposure/recovery experiments; their timings are not substituted for the labeled panels. Samples were fixed with glutaraldehyde and osmium tetroxide, ethanol-dehydrated, uranyl-acetate-stained, resin-embedded and sectioned at 80 nm. Exact final medium pH and a molecular analysis of the two stock solutions are not reported for this microscopy comparison.
Curated Evidence Points:
Support
Source:
hirth_2024
Results, No appearance of gold nanoparticles in the periplasm; Figure 2A and its caption; Methods, Bacterial strains and growth conditions and Transmission electron microscopy: the previous stock gave source-assigned periplasmic particles after 72 h. The original Figure 2 was inspected. The figure is microscopy evidence with an author-assigned particle identity, not a new phase-resolved product-purity or bulk mass-balance measurement.
Partial
Source:
hirth_2024
Figure 2B-D and the same Results subsection retain the negative commercial-stock outcome: long exposures damaged cells, whereas the short-exposure panel showed cells without the reported particles. The authors discuss alternative directions of causality between toxicity and failed particle formation. The 70-h figure label differs from the general 72-h protocol and the prose description of three days. The figure does not quantify the fraction of all cells forming particles, a detection limit, or a conversion yield.
Partial
Source:
hirth_2024
Discussion, The procedure used to produce Au(III) solutions has biological consequences, and Conclusion propose stock-speciation, respiratory-chain and copper-homeostasis explanations. The specific chloride/hydroxide species and chlorine-manufacturing route are hypotheses here, not directly measured stock compositions or a demonstrated exclusive pathway. This microscopy comparison supplies no matched cell-free or killed-cell series establishing metabolic necessity. Laboratory particle association does not demonstrate permanent environmental immobilization, isolated gold recovery, or industrial deployment.
Context_only
Source:
hirth_2024_si
Supplementary Table S4 (PDF page 6) explicitly identifies AE104 as a plasmid-free derivative of CH34 and lists the genetic derivatives used elsewhere in the paper. These genotypes are not transferred to the parental AE104 microscopy panels; neither the strain table nor the species identifier proves a particular molecular mechanism.
Sources & References
-
chebi_gold: ChEBI:29287, gold atom; Au, charge zero, resolved through the EBI Ontology Lookup Service.
https://www.ebi.ac.uk/chebi/CHEBI:29287 (accessed 2026-10-14) -
ncbi_species: NCBI Taxonomy 119219: Cupriavidus metallidurans, species; this species identifier does not identify derivative AE104.
https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?id=119219 (accessed 2026-10-14) -
hirth_2024: Hirth et al. (2024). A gold speciation that adds a second layer to synergistic gold-copper toxicity in Cupriavidus metallidurans. Applied and Environmental Microbiology 90(4), e00146-24. DOI 10.1128/aem.00146-24; complete JATS original and original graphics.
https://doi.org/10.1128/aem.00146-24 (accessed 2026-10-14) -
hirth_2024_si: Hirth et al. (2024), supplementary tables and figures, aem.00146-24-s0001.pdf, 12 pages; Table S4 identifies AE104 and study derivatives.
https://www.ebi.ac.uk/europepmc/webservices/rest/PMC11022561/supplementaryFiles (accessed 2026-10-14)
Curation History
| Timestamp | Curator | Action | Summary |
|---|---|---|---|
2026-10-14T19:43:25Z |
Codex (GPT-6; Codex) | create | Created elemental gold identity and a narrowly scoped AE104 stock-comparison observation from verified identifiers, the complete 2024 original XML, original Figure 2 and official supplementary strain table. Retained the commercial-stock null/damage outcome, timing discrepancy, proposed stock chemistry, microscopy limits and missing causal controls; no criticality or recovery-yield claim. |
Record source: data/records/gold.yaml