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Topical Area: Nutritional Microbiology/Microbiome

Nutritional Microbiology/Microbiome (Poster Session)

(P20-023-23) NutriClay-Zn Harbors Bioactive Zinc and Suppresses Enterotoxigenic Salmonella typhimurium, Escherichia coli, and Staphylococcus aureus

Sunday, July 23, 2023
11:45 AM – 12:45 PM ET
Location: Poster Board 442

    Presenting Author(s)

  • SJ

    Steven J.T Jackson, PhD

    Adjunct Assistant Professor
    School of Agricultural Sciences, Southern Illinois University
    Champaign, Illinois, United States

    • Co-Author(s)

  • KA

    Kathleen Andrews

    Food and Feed Research Unit, Agricultural Research Service, U.S. Department of Agriculture

  • WB

    William J. Banz

    School of Agricultural Sciences, Southern Illinois University

  • GA

    Gary A. Apgar

    School of Agricultural Sciences, Southern Illinois University

  • RH

    Roger B. Harvey

    Food and Feed Research Unit, Agricultural Research Service, U.S. Department of Agriculture

  • TP

    Timothy D. Phillips

    Department of Veterinary Physiology & Pharmacology, Texas A&M University

Disclosure(s):
Steven J.T Jackson, PhD: No relevant financial relationship(s) with ineligible companies to disclose.


Objectives: Salmonella typhimurium, Escherichia coli, and Staphylococcus aureus represent foodborne pathogens that can trigger diarrhea and diminish weight gains in livestock, as well as lead to gastroenteritis in humans. Although antibiotics have been used historically on the farm to control the spread of pathogenic bacteria and promote animal growth, this practice may foster antimicrobial resistance and thereby deplete our arsenal of effective antibiotic therapies. Incorporation of free-chemical zinc oxide (ZnO) into animal feed has largely replaced the need for prophylactic antibiotics, yet concerns are mounting around environmental impacts of unabsorbed zinc being excreted in feces and deposited into soil and groundwater supplies. Here, NutriClayZn is described as a novel (and GRAS) feed ingredient with efficacy against Salmonella typhimurium, Escherichia coli, and Staphylococcus aureus, yet with limited release of free-chemical zinc.

Methods: Propagation of bacteria was assessed in dose-response experiments involving ZnO delivery via NutriClayZn at physiological gut concentrations. NutriClayyZn efficacy against bacterial growth was confirmed following pre-treatment with hydrochloric acid (pH2) as a model for passage through the stomach. Liberated zinc was quantified by ICP-MS as an indicator of potentially bioavailable zinc derived from NutriClayyZn.

Results: Two-log significant (p < 0.05) bacterial growth reductions were routinely observed upon 6-hour exposures to NutriClayZn (7.85 mg/mL) that liberated 0.09 mg zinc/mL, or an equivalent 1.11 mM free-chemical ZnO in culture medium. Acid pre-treatment liberated slightly more zinc (0.17 mg/mL), yet isolated residual NutriClayZn remained efficacious in producing two-log bacterial growth reductions while liberating only 0.01 mg zinc/mL (i.e., 0.12 mM free-chemical ZnO in culture). In contrast, achieving two-log bacterial growth reductions with direct addition of ZnO, devoid of clay, required 25X the exposure (i.e., 3 mM free-chemical ZnO in culture).

Conclusions: These findings suggest that NutriClayZn:
(1) harbors bioactive zinc and constrains enterotoxigenic bacteria,
(2) has superior potency compared to free-chemical ZnO administration, and
(3) modestly liberates zinc that may contribute to nutritional needs.

Funding Sources: Supported by USDA and Texas A&M AgriLife Research.