Antibacterial Activity of Clay Soils against Food-Borne Salmonella typhimurium and Staphylococcus aureus

Abstract

Natural clays have recently been proven to possess antibacterial properties. Effective natural antimicrobial agents are needed to combat bacterial contamination on food contact surfaces, which are increasingly more prevalent in the food chain. This study sought to determine the antibacterial activity of clays against the food-borne pathogens Salmonella Typhimurium ATCC 14028 and Staphylococcus aureus ATCC 13565. Soils were processed to yield leachates and suspensions from untreated and treated clays. Soil particle size, pH, cation-exchange capacity, metal composition and mineralogy were characterized. Antibacterial screening was performed on six Malaysian soils via the disc diffusion method. In addition, a time-kill assay was conducted on selected antibacterial clays after 6 h of exposure. The screening revealed that Munchong and Carey clays significantly inhibit Salmonella Typhimurium (11.00 ± 0.71 mm) and S. aureus (7.63 ± 0.48 mm), respectively. Treated Carey clay leachate and suspension completely kill Salmonella Typhimurium, while S. aureus viability is reduced (2 to 3 log10). The untreated Carey and all Munchong clays proved ineffective as antibacterials. XRD analysis confirmed the presence of pyrite and magnetite. Treated Carey clays had a higher soluble metal content compared to Munchong; namely Al (92.63 ± 2.18 mg/L), Fe (65.69 ± 3.09 mg/L) and Mg (88.48 ± 2.29 mg/L). Our results suggest that metal ion toxicity is responsible for the antibacterial activity of these clays.

Raw Smectite from the Guarapuava–Parana–Brasil Saturated with Copper Ions and Its Properties

“…The raw Sm and Sm/Dye did not show antimicrobial activity against S. aureus, L. monocytogenes, and C. albicans, and showed a low potential against E. coli. Azmi et al [47] reported the antibacterial activity of clays was not uniform due to differences in mineralogical and geochemical composition. The antibacterial activity of clay leachates was The color difference (∆E) obtained from the values of the L*, a*, and b* parameters for the new pigments before and after light exposure is shown in Figure 7b.…”

“…This antibacterial property can be explained by the Cu 2+ ions released continually from Cu-Sm in contact with bacteria [52,53] by a mechanism that, in general, is a The raw Sm and Sm/Dye did not show antimicrobial activity against S. aureus, L. monocytogenes, and C. albicans, and showed a low potential against E. coli. Azmi et al [47] reported the antibacterial activity of clays was not uniform due to differences in mineralogical and geochemical composition. The antibacterial activity of clay leachates was widely reported in the scientific literature and attributed to metal ion toxicity released from the clay mineral interlayer.…”

Active Coatings Development Based on Chitosan/Polyvinyl Alcohol Polymeric Matrix Incorporated with Thymol Modified Activated Carbon Nanohybrids

“…These findings emphasize the need to optimize formulations and concentrations to maximize the antibacterial activity of film materials for various applications, including food packaging and biomedical devices. Azmi et al (2022) provide insights into the various factors influencing the antibacterial properties of clay, which may be a significant avenue for future exploration if considering clay-based nanohybrids for antimicrobial applications [50].…”

Comparative Genomics, Phylogenetic and Functional Analysis of Yersinia enterocolitica, a Gastrointestinal Pathogen, with Other Soil-Borne Bacteria Causing Diseases

“…enterocolitica is frequently isolated from soil, water, and animals and can cause contamination in foods of all types [12]. It shares ecology with other bacteria such as Escherichia coli and is found in tropical and subtropical soils [13], Campylobacter jejuni is found in soil, roots, and shoots and causes gastroenteritis [14], Salmonella enterica causes contamination through the soil on which the plant is growing [15], Staphylococcus aureus is found in soil, water, and air and causes staphylococcal food poisoning [16], Clostridium perfringens is found frequently in soil, feces, and normal intestinal fl ora [17], Bacillus cereus is found in soil, vegetation, and food and causes intestinal illness with nausea, vomiting, and diarrhea; the soil is also the main habitat of Listeria monocytogenes and plays a pivotal role in the transmission of these bacteria from soil to plants and animals [18], and C. botulinum exists in soil, river, and sea and produces toxins in food.…”