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Illite group mineral group

Illite is represented as a mineral group, as designated in the IMA compendium nomenclature table, rather than an ideal single species or an undifferentiated clay commodity. The experimental material is the source-designated IMt-1 illite preparation. Its measured behavior is not transferred from the separate nontronite and montmorillonite studies that reported mixed illite-like transformation products. No phase-pure endmember, universal formula or constituent criticality designation is asserted.

Microbial & Biochemical Mechanisms (1)

Low-temperature culture-associated reduction and alteration of IMt-1 illite

redox transformation Microbial

Associated Organisms: Shewanella vesiculosa (NCBITaxon:518738)

Cultures assigned by the authors to Shewanella vesiculosa increased measured iron reduction and operationally dissolved total iron relative to uninoculated IMt-1 controls at low temperature. Diffraction broadening and altered particle surfaces accompany the response. The paper interprets these observations as reductive dissolution and secondary precipitation; exclusive structural-iron provenance and a complete recovery mass balance remain unestablished.

Experimental Context & Analytical Limits:
The Clay Minerals Society IMt-1 material was size-separated below 2 micrometres by gravitational settling and freeze-dried. An unnamed Antarctic isolate from the King Sejong Station area was grown in LB at 15 degrees C for seven days, washed three times, and inoculated at approximately 10^7 CFU/mL. Laboratory bottles contained 100 mL nitrogen-purged M1 medium, 4 g/L IMt-1 and nominal 20 mM sodium lactate, buffered with MOPS to pH 6, at 0 or 4 degrees C for up to 24 weeks. No strain accession or sequence-based verification is supplied. Samples were frozen at minus 70 degrees C and thawed before analysis. Acid/HF digestion followed by phenanthroline measured Fe(II)/total Fe; centrifuged, 0.45-micrometre-filtered liquid was analyzed by ICP-AES for total iron, not specifically Fe(II). Triplicate analytical sets are stated, without clear independent-bottle replication.
Curated Evidence Points:
Figures 1-2 distinguish inoculated 0/4-degree treatments from no-cell controls. The 4-degree reduction trajectory peaks early and then decreases before recovering; both biotic trajectories end near the source-reported 3.1% reduction at 24 weeks. Dissolved total iron rises through eight weeks and subsequently decreases, so the result is not monotonic accumulation. These conditional assay results establish culture-associated redox/mobilization, not a purified iron product or measured biological uptake.
Figures 3-5 and Table 2 support broadened illite peaks, changed morphology and source-assigned vivianite in the 4-degree biotic residue after 24 weeks. Limited diffraction peaks plus Fe-P-O EDS do not establish phase purity, quantitative conversion or exclusive origin of product iron. The medium contains phosphate and a metal supplement, and the paper does not provide phase-resolved Fe accounting or a complete recipe. Its claim that IMt-1 is the sole electron acceptor is retained as source design, not experimentally proved exclusivity; Table 1 additionally lists selenate. Proposed electron transfer in Figure 6 is a schematic, not a direct measurement.
Dithionite produced more operational Fe reduction and dissolved iron than the microbial treatments, but its two-hour duration is not time-matched to the multiweek cultures. Table 1 marks clay and dithionite without medium for that arm, whereas Methods say it was prepared similarly except for cells. The same table lists 2 M lactate/formate without clarifying stock versus final concentrations, in conflict with the prose nominal 20 mM lactate. Figure 4 labels K/(K+Ca), whereas Results use K/(K+2Ca); both chemical and biotic panels show the same final ratio, despite Discussion claiming greater biotic K enrichment. No differential K enrichment, exact complete medium recipe, pure-illite Fe yield or ocean/industrial-scale performance is inferred.

Sources & References

  1. ima_compendium_2019: Schertl, Mills and Maresch, editors (2019 copyright). A Compendium of IMA-Approved Mineral Nomenclature, prepared for IMA2018. PDF p34 reproduces Whitney and Evans (2010), Abbreviations for names of rock-forming minerals, DOI 10.2138/am.2010.3371; Table 1 marks chlorite and illite GROUP. Historical nomenclature table, not a 2026 species approval.
    https://cnmnc.units.it/ima_reports/2%20IMA-Nomenclature-e-Booklet-2019-1.pdf (accessed 2026-10-14)
  2. jung_2022: Jung, Chung, Ko, Moon, Suh and Kim (2022). A microbial driver of clay mineral weathering and bioavailable Fe source under low-temperature conditions. Frontiers in Microbiology 13:980078. DOI 10.3389/fmicb.2022.980078; PMCID PMC9441888. Complete ten-page original, Methods pp2-3, Figures 1-6 and Tables 1-2.
    https://doi.org/10.3389/fmicb.2022.980078 (accessed 2026-10-14)
  3. ncbi_vesiculosa: NCBI Taxonomy 518738, Shewanella vesiculosa, species; current taxonomy XML inspected 14 October 2026. Species mapping does not identify the unnamed experimental isolate as type strain M7.
    https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?id=518738&mode=Info (accessed 2026-10-14)

Curation History

Timestamp Curator Action Summary
2026-10-14T16:33:06.577518+00:00 codex (GPT-6; codex) CREATE Created illite-group owner from complete primary microbial experiments with explicit source, phase and assay limitations.

Record source: data/records/illite.yaml