Abstract
Salmonella Typhimurium and Escherichia coli represent foodborne pathogens that can trigger diarrhea and diminish weight gains in livestock, as well as cause gastroenteritis in humans. Although prophylactic antibiotics have been used historically on the farm to limit bacterial pathogens and promote animal growth, this practice may also foster antimicrobial resistant (AMR) strains of bacteria and deplete our arsenal of effective antibiotic therapies. Incorporation of free chemical zinc oxide (ZnO) into animal feed, at doses far above nutritional requirements, has largely replaced prophylactic antibiotics; however, environmental concerns are mounting around unabsorbed zinc (excreted in feces) impacting soil microbes and thereby contributing to the AMR threat. Here, NutriClay(Zn) is introduced as an analog of montmorillonite (MMT) clay with potent efficacy against foodborne bacterial pathogens and slow release of low concentrations of zinc. Bacterial propagation was assessed in culture experiments using NutriClay(Zn) dosages aligned with current dietary MMT clay practices for the control of aflatoxin in production animals. Zinc release was quantified by inductively coupled plasma mass spectrometry. Significant (p < 0.05) growth reduction of Salmonella Typhimurium was observed following NutriClay(Zn) exposures releasing less zinc than that contained within free chemical ZnO positive controls. Moreover, NutriClay(Zn) displayed dose-dependent efficacy against an AMR strain of Escherichia coli O157:H7, while also binding aflatoxin B1 with kinetics similar to its parent MMT clay. These findings suggest that NutriClay(Zn) could serve as a dual-purpose dietary substance, binding aflatoxin B1 and suppressing enterotoxigenic bacteria that can compromise the food supply.