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Microbial Metallomics
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A qualitative mechanism explorer

Follow the metal.

Choose a case. Trace the compartments. Find the connection that still needs evidence.

These diagrams organize findings from distinct studies. Arrows describe a proposed route through the question; they do not mean that every step has been demonstrated in one experiment. There are no calculated doses or predicted patient outcomes.

Human absorption + separate microbial models

Does more zinc reach the host—or less reach the microbes?

One input, two access questions
  • Formulation in the gut

    Aspartate, oxide, sulfate, and gluconate are formulation labels. The human comparisons tested different subsets under different food and measurement conditions. [1] [2]

  • Host branch · uptake

    A higher absorbed fraction describes entry into the host. It does not identify how much remaining zinc is usable by a particular gut organism.

  • Microbial branch · local access

    Calprotectin and microbial acquisition machinery can change competition in an inflamed niche. This was studied separately from the human formulation comparisons. [3]

The tempting inference is that better host absorption leaves less zinc for microbes. That may change total residual exposure, but chemical accessibility, timing, and location still need measurement. “Aspartate bypasses microbes” remains an untested explanation in the evidence assembled here.

Open the formulation and MS evidence ledger

Cellular mechanism + human intervention evidence

The dose enters the gut. Does usable iron reach the marrow?

Separate entry, export, and use
  1. Intestinal exposure

    Oral replacement introduces iron into the lumen. Its microbial and metabolic effects can differ from intravenous delivery. [4]

  2. Host export

    Hepcidin binding to ferroportin reduces cellular iron export. Iron can be retained while circulating delivery falls. [5]

  3. Red-cell production

    Hemoglobin response is a host outcome, not a direct readout of microbial feeding. A biomarker-guided reduction in exposure did not preserve efficacy in one child trial. [6]

First distinguish depleted stores, inflammatory restriction, and mixtures. Even in inflammatory bowel disease, depleted stores can accompany low hepcidin. Inflammation does not guarantee a closed export gate in every patient. [7]

Open the iron depletion and restriction map

Distinct cellular, chemical, and human-specimen studies

A metal delivered as a defense can meet a microbial buffer.

Opposing processes, assembled across studies
  1. Host trafficking

    A macrophage study implicated ATP7A-dependent copper delivery in antibacterial activity. [8]

  2. Microbial ligand

    Yersiniabactin binds copper and can protect bacteria from its toxicity. [9]

  3. Infection compartment

    Copper–yersiniabactin complexes were detected in human urinary infection specimens. Detection does not establish their contribution to each patient’s severity. [9]

The missing connection is simultaneous measurement of host delivery, ligand-bound versus accessible copper, and the host outcome in the same setting. A total copper result cannot supply all three. These studies do not establish that changing dietary copper would reproduce either mechanism.

Read the copper profile

Gut bacterial mechanisms + a mouse supplementation study

The cobalt atom does not tell you who can use the molecule.

Chemical identity meets selective access
  1. Corrinoid mixture

    Vitamin B12 and related corrinoids contain cobalt. Their molecular differences matter to microbial use. [10]

  2. Transporter repertoire

    Multiple transporters can discriminate among analogs; transferable transport capacity can change competition within a species. [10] [11]

  3. Community and host

    Oral B12 altered distal-gut corrinoids and some bacterial abundances in mice without changing the measured colitis outcome. [12]

The transporter studies have not shown that transporter selectivity caused the separate supplementation-associated community shift. Nor do they establish whether a particular community’s corrinoid handling limits host benefit in a defined clinical setting. Free cobalt supplementation is not an equivalent intervention.

Read the cobalt profile

Follow the connections

Host metal defensesBinding, redistribution, buffering, and biliary export: follow the host strategies and their competing effects.

Sources & further reading

Primary studies supporting the linked statements. The framework and proposed experiments are editorial synthesis, not a clinical guideline or a systematic review.

  1. Piacenza F, Giacconi R, Costarelli L, Malavolta M (2023). Preliminary Comparison of Fractional Absorption of Zinc Sulphate, Zinc Gluconate, and Zinc Aspartate after Oral Supplementation in Healthy Human Volunteers. View source↩
  2. Wegmüller R, Tay F, Zeder C, Brnic M, Hurrell RF (2014). Zinc absorption by young adults from supplemental zinc citrate is comparable with that from zinc gluconate and higher than from zinc oxide. View source↩
  3. Liu JZ, Jellbauer S, Poe AJ, Ton V, Pesciaroli M, Kehl-Fie TE, Restrepo NA, Hosking MP, Edwards RA, Battistoni A, Pasquali P, Lane TE, Chazin WJ, Vogl T, Roth J, Skaar EP, Raffatellu M (2012). Zinc sequestration by the neutrophil protein calprotectin enhances Salmonella growth in the inflamed gut. View source↩
  4. Lee T et al. (2017). Oral versus intravenous iron replacement therapy distinctly alters the gut microbiota and metabolome in patients with IBD. View source↩
  5. Nemeth E et al. (2004). Hepcidin regulates cellular iron efflux by binding to ferroportin and inducing its internalization. View source↩
  6. Wegmüller R et al. (2023). Hepcidin-guided screen-and-treat interventions for young children with iron-deficiency anaemia in The Gambia: an individually randomised, three-arm, double-blind, controlled, proof-of-concept, non-inferiority trial. View source↩
  7. Mecklenburg I et al. (2014). Serum hepcidin concentrations correlate with ferritin in patients with inflammatory bowel disease. View source↩
  8. White C et al. (2009). A role for the ATP7A copper-transporting ATPase in macrophage bactericidal activity. View source↩
  9. Chaturvedi KS et al. (2012). The siderophore yersiniabactin binds copper to protect pathogens during infection. View source↩↩
  10. Degnan PH et al. (2014). Human gut microbes use multiple transporters to distinguish vitamin B₁₂ analogs and compete in the gut. View source↩↩
  11. Frye KA et al. (2021). Mobilization of vitamin B12 transporters alters competitive dynamics in a human gut microbe. View source↩
  12. Kelly CJ et al. (2019). Oral vitamin B12 supplement is delivered to the distal gut, altering the corrinoid profile and selectively depleting Bacteroides in C57BL/6 mice. View source↩