Whitlockite mineral
Whitlockite is a calcium-magnesium hydrogen phosphate mineral. The September 2026 IMA list gives ideal Ca9 vacancy Mg(PO3OH)(PO4)6 and grandfathered status G with original-description year 1941; the vacancy is a structural site and the year is not an approval accession. It is distinct from beta-tricalcium phosphate, apatite minerals, amorphous calcium phosphate and phosphate resources. The curated microbial experiment reports a whitlockite-assigned product but explicitly retains Mg-stabilized beta-TCP as an alternative assignment; this record does not assert unambiguous phase purity. No constituent criticality is inherited.
Microbial & Biochemical Mechanisms (1)
Culture-associated crystallization of whitlockite-assigned calcium phosphate
biomineralization
Microbial
Associated Organisms:
Carboxydothermus hydrogenoformans (NCBITaxon:129958)
An initially abiotic amorphous calcium-phosphate precipitate became crystalline during laboratory culture of C. hydrogenoformans DSM 6008. The dominant granular product was assigned to magnesium whitlockite using diffraction, composition and infrared evidence, but the authors also allow Mg-stabilized beta-TCP. A second nanorod product was only interpreted as hydroxyapatite-like. The experiment supports culture-associated crystallization, not unequivocal pure-whitlockite biosynthesis, a demonstrated molecular mechanism or isolated phosphorus recovery.
Experimental Context & Analytical Limits:
Haddad2014 used anaerobic 500 mL bottles containing 200 mL medium and 300 mL initial 100% CO headspace at 1 atm, 70 degrees C and 150 rpm; initial pH was 6.8-7.0. Basal salts in g/L were KCl 0.33, MgCl2.6H2O 0.52, CaCl2.2H2O 0.29, NH4Cl 0.33 and KH2PO4 0.33, with 10 mL/L trace-metal stock. Additions per litre were 20 mL of 5% NaHCO3, 10 mL of 2.5% Na2S.9H2O, 10 mL of 0.5% yeast-extract stock and 1 mL vitamin solution. Exact inoculum amount was not reported. Most phase comparison concerns 30-day material; bulk metal/P composition is from a separate 39-day sample and protein assays from four independent 21-day cultures. Samples were washed and dried at 105 degrees C overnight; some inoculated products were subsequently calcined at 600 degrees C. Sterile and inoculated preparations differed in washing and thermal treatment. Mg-stabilized beta-TCP remains an explicit alternative to whitlockite; neither nanorod morphology nor a reference-pattern match alone proves a pure mineral product.
Haddad2014 used anaerobic 500 mL bottles containing 200 mL medium and 300 mL initial 100% CO headspace at 1 atm, 70 degrees C and 150 rpm; initial pH was 6.8-7.0. Basal salts in g/L were KCl 0.33, MgCl2.6H2O 0.52, CaCl2.2H2O 0.29, NH4Cl 0.33 and KH2PO4 0.33, with 10 mL/L trace-metal stock. Additions per litre were 20 mL of 5% NaHCO3, 10 mL of 2.5% Na2S.9H2O, 10 mL of 0.5% yeast-extract stock and 1 mL vitamin solution. Exact inoculum amount was not reported. Most phase comparison concerns 30-day material; bulk metal/P composition is from a separate 39-day sample and protein assays from four independent 21-day cultures. Samples were washed and dried at 105 degrees C overnight; some inoculated products were subsequently calcined at 600 degrees C. Sterile and inoculated preparations differed in washing and thermal treatment. Mg-stabilized beta-TCP remains an explicit alternative to whitlockite; neither nanorod morphology nor a reference-pattern match alone proves a pure mineral product.
Curated Evidence Points:
Support
Source:
haddad2014
Figures 2-4 compare dried 30-day inoculated material, its calcined counterpart, commercial beta-TCP and reference whitlockite (JCPDS 01-070-1786) with a dried 30-day sterile control. The inoculated solid has sharp peaks matching the whitlockite reference, whereas the sterile solid remains amorphous by XRD. Figure 5 shows phosphate-band differences for calcined inoculated versus dried sterile material. Figures 6 and 8 show Mg-bearing granules, association with biofilm and lattice fringes. Together these support the source-assigned crystalline product and the culture-associated contrast, subject to the explicit phase ambiguity.
Partial
Source:
haddad2014
Results/Discussion page 12 explicitly describes the dominant product as whitlockite or Mg-stabilized beta-TCP. XRD profiles of these phases are similar; infrared characterization uses calcined material, and bulk Table 2 composition is not a phase-specific stoichiometric analysis. The authors report TOPAS profile fitting, lattice parameters and crystallite sizes, but not refined phase fractions or a hydrogen-site determination for the culture product; no independent re-refinement was performed here. Nanorods in Figures 9-11 are interpreted as hydroxyapatite-like, not verified pure hydroxylapatite. Reported 91.7% and 100% values are relative crystallinity estimates against a beta-TCP reference, not mineral purity, conversion yield or recovered phosphorus.
Partial
Source:
haddad2014
Figure 1 and Results show initial precipitation and phosphate depletion in both sterile and inoculated medium after NaHCO3 addition. Suspended-solid concentration after 30 days was reported as comparable to that within two hours in either arm. Therefore initial precipitation is not a microbial effect or additional net product yield. Later transient phosphate changes do not close a phase-specific mass balance.
Support
Source:
haddad2014
The 30-day sterile medium did not develop the observed crystalline product. A separate control incubated sterile amorphous precipitate for 15 days at 70 degrees C in filtered previously inoculated medium and remained amorphous by XRD. Modified medium with lower Ca/Mg/phosphate/bicarbonate formed no detectable precipitate with or without live culture over 30 days. These are useful conditional controls, not demonstrations of a particular enzyme or a universal biological requirement for whitlockite formation.
Partial
Source:
haddad2014
Biofilm-mediated dissolution/reprecipitation and Mg chelation are proposed explanations, not directly measured molecular causes. Biomolecular analyses were negative. No matched killed-cell series is described. Inoculated products were generally washed three times and sterile material once because it dissolved readily; the 39-day chemical assay instead reports two washes. Methods give 600 degrees C for two hours, while Results describe one hour. These treatment differences and conflicting duration are retained rather than equated. General replicate counts and error-bar definitions for phase/time-course comparisons are not clearly specified; the four independent cultures apply specifically to protein assays.
Context_only
Source:
izatulina2019
A different 37 degrees C, approximately one-day model-urine experiment reports whitlockite in no-additive chemical syntheses, with the reported phase fields shown in Figure 3 and Section 3.2. This limits any claim that microorganisms are universally necessary. The article provides phase-summary charts rather than the raw whitlockite diffraction patterns, and its medium, pH and organism arms are not replication of the 70 degrees C DSM6008 experiment. No mineral-purity or microbial recovery yield is transferred from it.
Context_only
Source:
ncbi_hydrogenoformans
The species identifier and name are verified independently; the DSM6008 inoculum provenance is reported by the primary paper, not established by the species TaxID.
Partial
Source:
haddad2014
The recovered analytical pellet contained biomass and mixed calcium-phosphate material that could not be physically separated before characterization. Laboratory precipitation and proposed bioceramic applications do not establish purified-whitlockite recovery, clinical performance or industrial deployment.
Sources & References
-
ima_2026_09: IMA-CNMNC. The New IMA List of Minerals, September 2026: introductory definitions and Whitlockite row, PDF page 234. Previously acquired original re-inspected on the access date.
https://cnmnc.units.it/files/editor/IMA_Master_List_(2026-09).pdf (accessed 2026-10-14) -
handbook_whitlockite: Handbook of Mineralogy, Whitlockite, version 1 (2001-2005). Complete one-page formula, crystallography and occurrence; historical (Mg,Fe2+) compositional notation.
https://www.handbookofmineralogy.org/pdfs/whitlockite.pdf (accessed 2026-10-14) -
haddad2014: Haddad, Vali, Paquette and Guiot (2014). The Role of Carboxydothermus hydrogenoformans in the Conversion of Calcium Phosphate from Amorphous to Crystalline State. PLOS ONE 9:e89480. Complete 14-page original, Figures 1-11 and Tables 1-2; Methods and Results/Discussion.
https://doi.org/10.1371/journal.pone.0089480 (accessed 2026-10-14) -
izatulina2019: Izatulina et al. (2019). Bacterial Effect on the Crystallization of Mineral Phases in a Solution Simulating Human Urine. Crystals 9:259. Complete 11-page original, Methods, Figures 1-4 and Tables 1-4; different chemical and biological experimental system.
https://doi.org/10.3390/cryst9050259 (accessed 2026-10-14) -
ncbi_hydrogenoformans: NCBI Taxonomy 129958: Carboxydothermus hydrogenoformans, species node. The experiment reports DSM 6008; the species node is not a strain identifier.
https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?id=129958&mode=Info (accessed 2026-10-14)
Curation History
| Timestamp | Curator | Action | Summary |
|---|---|---|---|
2026-10-14T16:31:44.836542Z |
codex (GPT-6; codex) | CREATE | Added authoritative whitlockite identity and explicitly qualified culture-associated crystallization, preserving the Mg-stabilized beta-TCP alternative, abiotic starting precipitation, distinct control arms and sample-treatment inconsistencies. |
Record source: data/records/whitlockite.yaml