Muhammad et al. 2021 - Lactobacillus lead bioremediation

Muhammad and colleagues tested whether free or maize-resistant-starch microencapsulated Lactobacillus acidophilus KLDS strains could bind Pb in vitro and reduce Pb body burden in a chronic mouse exposure model. This is mitigation and detoxification evidence, not product occurrence evidence: the study used Pb nitrate-spiked media and drinking water and should not contribute to HMTc occurrence or threshold pools.

Key numbers

In vitro Pb binding

Table 2 reports Pb removal from 100 mg/L Pb nitrate solution by wet bacterial biomass and minimum inhibitory concentration for six L. acidophilus KLDS strains. Values are mean +/- SD of three determinations for MIC; different letters indicate p < 0.05.

Table 3 reports Langmuir and Freundlich isotherm constants for Pb binding by L. acidophilus KLDS 1.1003 biomass. The Langmuir model reported qmax = 6.1124 mg metal/g biosorbent, KL = 0.3204, RL = 0.0587, and R2 = 0.9052. The Freundlich model reported 1/n = 1.4118, Kf = 25.8134, and R2 = 0.9842.

Mouse Pb body burden

Table 1 describes six mouse groups, n = 10 each. Pb-exposed groups received lead nitrate at 100 mg/L in drinking water for 7 weeks. Treatment groups received free or MRS-based encapsulated L. acidophilus KLDS 1.1003 in skimmed milk by daily gavage; the text gives 1.3 x 10^9 CFU in the methods and the table note gives 1.4 x 10^9 CFU.

Figure 6 and the surrounding results text report that Pb-only mice had 142.5 +/- 5.817 ug/L Pb in blood. Free L. acidophilus KLDS 1.1003 plus Pb reduced blood Pb to 127.92 +/- 5.220 ug/L, and MRS-encapsulated L. acidophilus KLDS 1.1003 plus Pb reduced blood Pb to 101.47 +/- 4.142 ug/L.

For tissue Pb, the Pb-only group had 21.36 +/- 0.872 ug/g in liver and 23.13 +/- 0.944 ug/g in kidney. Free L. acidophilus KLDS 1.1003 plus Pb reduced liver Pb to 7.27 +/- 0.296 ug/g and kidney Pb to 19.86 +/- 0.810 ug/g. MRS-encapsulated L. acidophilus KLDS 1.1003 plus Pb reduced liver Pb to 6.42 +/- 0.262 ug/g and kidney Pb to 18.02 +/- 0.735 ug/g.

Essential element shifts

Table 4 reports Zn, Ca, Mg, and Fe in mouse liver and kidney after the same 7-week exposure. In liver, the Pb-only group had Ca 241.70 +/- 1.33, Mg 209.22 +/- 2.26, and Fe 34.04 +/- 1.72, while the MRS-encapsulated L. acidophilus plus Pb group had Ca 303.09 +/- 1.52, Mg 237.31 +/- 2.02, and Fe 46.94 +/- 2.34. In kidney, the Pb-only group had Zn 22.32 +/- 1.11, Ca 824.27 +/- 3.09, Mg 202.62 +/- 0.03, and Fe 48.29 +/- 2.41, while the MRS-encapsulated L. acidophilus plus Pb group had Zn 20.93 +/- 1.04, Ca 837.26 +/- 3.23, Mg 204.21 +/- 1.04, and Fe 54.87 +/- 2.74. The table does not state a unit in the extracted text, so these values are retained only as source-reported tissue element values, not converted product concentrations.

Methods (brief)

Six L. acidophilus KLDS strains were screened for Pb tolerance and wet-biomass Pb removal after incubation with Pb nitrate. The selected strain, L. acidophilus KLDS 1.1003, was also tested in maize-resistant-starch microencapsulated form; SEM/EDS and FTIR were used to characterize Pb binding on bacterial and encapsulated biomass surfaces. For the animal model, adult female BALB/c mice were divided into six groups of ten and exposed for 7 weeks to plain water or 100 mg/L Pb nitrate in drinking water, with or without daily gavage of free or MRS-encapsulated L. acidophilus in skimmed milk. Pb in blood was measured using a BH 2100 kit; liver and kidney samples were nitric-acid digested and measured by flame atomic absorption spectrophotometry. The reported Pb values are blood and tissue body-burden endpoints from a spiked animal model, not food, supplement, or ingredient occurrence values.

Implications

Certification: Do not use this source in HMTc occurrence pools for supplements, probiotics, enzymes, maize starch, or any food row. The Pb exposure was experimentally spiked and the endpoints are Pb binding and mouse body burdens.

Courses: Useful for teaching the firewall between mitigation/detoxification evidence and occurrence evidence. It also provides a concrete example of microbial biosorption, functional-group binding evidence, and the need to record dose-model contradictions.

App: Context only for mitigation education; it does not support consumer-facing claims that a probiotic supplement removes Pb in humans.

Wiki pages this source may touch

• formulation
• remediation-evidence
• lead
• zinc
• iron
• magnesium
• index

Verification notes

This page was built from the full PDF text, including the abstract, Table 1 animal protocol, Table 2 strain Pb removal and MIC, Table 3 isotherm constants, Figure 6 Pb blood/liver/kidney values, Table 4 essential-element tissue values, methods, and discussion. Products and ingredients are intentionally empty because the study does not measure heavy metals in a marketed supplement, enzyme product, food ingredient, or consumer product. The auto-fetch filename targeted supplements/enzymes/Pb, but the actual paper is a probiotic mitigation study.

The source contains a small internal dose discrepancy: the animal-methods paragraph states 1.3 x 10^9 CFU of L. acidophilus KLDS 1.1003 in 0.5 ml skimmed milk, while Table 1’s note states 1.4 x 10^9 CFU. Both are recorded above; this does not block routeability because the direction and magnitude of Pb body-burden endpoints are clear.

Calcium was measured in Table 4 alongside Zn, Mg, and Fe, but is omitted from the metals: frontmatter because calcium is not in the HMI metals vocabulary (no metals/calcium page; tracked only as an essential-element companion to Pb exposure). Ca values are retained in the body table for completeness.

The matrices vocabulary used here (probiotic-biosorption, mouse-blood, mouse-liver, mouse-kidney, lead-spiked-drinking-water) is ad-hoc but consistent with the established pattern for mitigation and animal-model source pages, which lack a food-form-oriented controlled vocabulary. GPT-5.5-style audit (2026-06-09) flagged these as out-of-controlled-vocab; verified against sibling mitigation pages (e.g., chen2023-clinoptilolite-cd-mitigation uses cd-spiked-drinking-water, mouse-liver-tissue, clinoptilolite-feed-additive in the same pattern), so the finding was a false positive.

Page history

The five most recent substantive edits to this page. The full version history lives in git; when DOI minting comes online (see schema docs), each entry below will also link to a version-pinned DataCite DOI.