Enstatite mineral
Enstatite is the Mg2Si2O6 mineral species listed as approved through a 1988 special procedure in the September 2026 IMA list. The special-procedure year is not a unique approval-number identifier. This species is distinct from elemental magnesium and from the mixed San Carlos experimental feed, which contained 31 wt% enstatite and 69 wt% olivine by the authors' XRD characterization. No constituent criticality is inherited. The companion olivine-group record describes other material scope within the same Klug experiment, not an independent replication.
Microbial & Biochemical Mechanisms (1)
Enstatite-bearing mixed-feed leaching by engineered bacterial biolixiviant
bioleaching
Microbial
Associated Organisms:
Gluconobacter oxydans (NCBITaxon:442)
An enstatite-bearing olivine mixture released Mg and Ni into the analyzed liquid fraction in both cell-containing and cell-free bacterial-biolixiviant arms. XRD and the authors' mass-balance model are consistent with partial enstatite dissolution, but the study did not test a pure-enstatite feed or measure enstatite-specific aqueous flux.
Experimental Context & Analytical Limits:
The selected feed was the 69 wt% olivine/31 wt% enstatite bulk powder, not the separate hand-selected olivine-only arm. The strain was Gluconobacter oxydans B58 delta-pstS, P112:mgdh, propagated from one colony; triplicate flasks per arm and sampling day were technical replicates from that shared culture. YPM growth and glucose-based biolixiviant production each lasted two days at 30 degrees C and 200 rpm. Prepared cell-containing cultures and centrifuged, 0.2-micrometre-filtered biolixiviant were tested separately. Each 100-mL flask contained 10 mL liquid and 0.5 g powder (5% pulp), incubated statically at 30 degrees C for 0, 5, 10 or 15 days. The Methods temperature takes precedence over the Introduction's room-temperature shorthand. Powders had typical particle size 40 micrometres after 20 minutes of tungsten-carbide milling; visibly carbonate-coated/altered grains were removed and a 60-minute deionized-water ultrasonic wash preceded milling. Powder sterilization was 135 degrees C for three minutes. Controls contained 20% glucose and mineral without cells or biolixiviant, with no acid or pH matching. Species taxon 442 does not identify the engineered genotype.
The selected feed was the 69 wt% olivine/31 wt% enstatite bulk powder, not the separate hand-selected olivine-only arm. The strain was Gluconobacter oxydans B58 delta-pstS, P112:mgdh, propagated from one colony; triplicate flasks per arm and sampling day were technical replicates from that shared culture. YPM growth and glucose-based biolixiviant production each lasted two days at 30 degrees C and 200 rpm. Prepared cell-containing cultures and centrifuged, 0.2-micrometre-filtered biolixiviant were tested separately. Each 100-mL flask contained 10 mL liquid and 0.5 g powder (5% pulp), incubated statically at 30 degrees C for 0, 5, 10 or 15 days. The Methods temperature takes precedence over the Introduction's room-temperature shorthand. Powders had typical particle size 40 micrometres after 20 minutes of tungsten-carbide milling; visibly carbonate-coated/altered grains were removed and a 60-minute deionized-water ultrasonic wash preceded milling. Powder sterilization was 135 degrees C for three minutes. Controls contained 20% glucose and mineral without cells or biolixiviant, with no acid or pH matching. Species taxon 442 does not identify the engineered genotype.
Curated Evidence Points:
Support
Source:
klug_2026_data
ICP-MS data worksheet, row 6, gives day-15 Mg means of about 8487 ppm with cells (T6), 7051 ppm in cell-free biolixiviant (AD6), and 265 ppm in the glucose-only mixed-feed control (J6). The workbook uses ppm as mg/L in its mass calculations, not native mg/kg observations. XRD minerals rows 7, 13 and 15 report enstatite in all three corresponding residues; Mg-oxalate is assigned in the direct residue but not in the mixed-feed cell-free or control residues.
Partial
Source:
klug_2026
Figure 6c-d attributes about 26% of total initial feed Mg to enstatite at day 0, with about 13% remaining in that phase with cells versus about 10% in the cell-free arm at day 15. Thus, the source's higher total mixed-feed leaching with cells does not establish superior enstatite-specific dissolution. These are model allocations based on assumed MgSiO3 and olivine Mg1.81Fe0.19SiO4 compositions, ICP-MS and XRD phase proportions, not direct phase-specific recovered masses.
Partial
Source:
klug_2026_si
Table S1 imports an average commercial San Carlos olivine composition from Lambart et al. (2022), rather than measuring this exact experimental batch. Figure S2 distinguishes the 69/31 mixture from the olivine-only material; Figure S4 preserves the cell-free mixed-feed Mg-oxalate null. Phase percentages describe residual solids rather than yields from the original mineral feed.
Partial
Source:
klug_2026
Leachate was centrifuged at 3214 x g for 20 minutes, frozen, thawed, passed through 0.45-micrometre filter plates and diluted 10000-fold in nitric acid for ICP-MS. Reported Mg and Ni were blank-corrected by about 1043 and 3.2 ppm respectively using a 100-fold-dilution comparison. These operationally defined filtrate concentrations are not isolated-product yields or resolved chemical species. Initial treated pH was about 2.4-2.5 but controls were about 8.7; later direct and cell-free pH trajectories also differed. The experiment does not isolate physical contact from evolving acid/metabolite chemistry, demonstrate a particular Fe-oxidation enzyme, or compare this mutant with wild type for mineral leaching. Laboratory results establish no industrial deployment or net atmospheric carbon removal.
Sources & References
-
ima_2026_09: IMA-CNMNC. The New IMA List of Minerals, September 2026; PDF page 63, Enstatite row; pages 1-2, definitions and terms.
https://cnmnc.units.it/files/editor/IMA_Master_List_(2026-09).pdf (accessed 2026-10-11) -
klug_2026: Klug et al. (2026). Bioleaching of olivine and enstatite with formation of Mg-oxalate mediated by engineered Gluconobacter oxydans. Scientific Reports 16:25317. DOI 10.1038/s41598-026-63817-0; Methods, Figures 2-6 and Discussion.
https://doi.org/10.1038/s41598-026-63817-0 (accessed 2026-10-11) -
klug_2026_data: Klug et al. (2026), Supplementary Material 1: leachate pH, ICP-MS data, XRD minerals and Mg, Fe, Ni mass balance calcs worksheets. Same experiment as the main article.
https://pmc.ncbi.nlm.nih.gov/articles/instance/13473492/bin/41598_2026_63817_MOESM1_ESM.xlsx (accessed 2026-10-11) -
klug_2026_si: Klug et al. (2026), Supplementary Material 2: Table S1 and Figures S1-S4; assumed commercial San Carlos composition, Raman assignment, feed mixture and direct versus cell-free XRD.
https://pmc.ncbi.nlm.nih.gov/articles/instance/13473492/bin/41598_2026_63817_MOESM2_ESM.docx (accessed 2026-10-11) -
ncbi_oxydans: NCBI Taxonomy 442 - Gluconobacter oxydans, species rank; XML checked 11 October 2026. This identifier does not resolve the engineered B58 derivative.
https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?id=442&mode=Info (accessed 2026-10-11)
Curation History
| Timestamp | Curator | Action | Summary |
|---|---|---|---|
2026-10-11T10:51:44.051000+00:00 |
codex (GPT-6; codex) | CREATE | Created enstatite species record with mixed-feed leaching evidence and phase-specific mass-balance limits. |
Record source: data/records/enstatite.yaml