Silver nanoparticles-essential oils combined treatments to enhance the antibacterial and antifungal properties against foodborne pathogens and spoilage microorganisms

Authors: BEGUM, T - Institut National De La Recherche Scientifique (INRS); Follett, Peter; MAHMUD, J - Institut National De La Recherche Scientifique (INRS); MOSKOVCHENKO, L - Institut National De La Recherche Scientifique (INRS); SALMIERI, S - Institut National De La Recherche Scientifique (INRS); ALLAHDAD, Z - Institut National De La Recherche Scientifique (INRS); LACROIX, M - Institut National De La Recherche Scientifique (INRS)

Submitted to: Microbial Pathogenesis
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/17/2022
Publication Date: 1/21/2022
Citation: Begum, T., Follett, P.A., Mahmud, J., Moskovchenko, L., Salmieri, S., Allahdad, Z., Lacroix, M. 2022. Silver nanoparticles-essential oils combined treatments to enhance the antibacterial and antifungal properties against foodborne pathogens and spoilage microorganisms. Microbial Pathogenesis. 164. Article 105411. https://doi.org/10.1016/j.micpath.2022.105411.
DOI: https://doi.org/10.1016/j.micpath.2022.105411

Interpretive Summary: Plant essential oils and silver nanoparticles can have antibacterial and antifungal effects. Several plant-derived essential oils (EOs) with and without silver nanoparticles were tested against two pathogenic bacteria (E. coli, and Salmonella Typh.) and three fungi (Aspergillus, Penicillium, Mucor) that can contaminate rice. All the EOs in combination with silver nanoparticles showed significant reductions in bacteria and fungi in vapor assays and in bags of rice and have potential to improve food safety.

Technical Abstract: Plant-derived essential oils (EOs) and commercial silver nanoparticles (AgNPs) were tested to evaluate their antibacterial and antifungal efficiency against two pathogenic bacteria (Salmonella Typhimurium and Escherichia coli O157:H7) and three spoilage fungi (Aspergillus niger, Penicillium chrysogenum, Mucor circinelloides). A broth microdilution assay was used to determine the minimal inhibitory concentration (MIC) of EOs and AgNPs. In the MIC assay, the cinnamon EO, Mediterranean EO, citrus EO and spherical-shaped silver nanoparticles (AgNPs) (AGC 1, AGC 0.5, AGPP and AGPPH) showed moderate to high antibacterial and antifungal properties, with MIC ranging from 7.8 to 62.5 ppm for AgNPs and 312.5 to 1250 ppm for EOs against the tested bacteria and fungi. The possible interaction between the EOs and the AgNPs was determined using a checkerboard method by evaluating fractional inhibitory concentration (FIC) values. The combination of two or more EOs and AgNPs (Active combination 1: AGPPH+cinnamon EO, Active combination 2: AGC 0.5+Mediterranean EO+citrus EO,Active combination 3: AGPP+cinnamon EO+Asian formulation EO+lavang EO) showed synergistic effects (FIC < 1.0) against all tested bacteria and fungi. A modified Gompertz model was used to evaluate growth parameters including maximum colony diameter (A), maximum growth rate (Vm), and lag phase ('), under the three active combinations suggested by the checkerboard method using a vapor assay. The three active combinations 1, 2 and 3 were reduced the growth rate and maximum colony diameter of E. coli, S. Typhimurium, A. niger, P. chrysogenum, and M. circinelloides, and extended their lag phase from 1-5 days. In in situ tests with inoculated rice, the three active combinations showed a significant reduction of all tested bacteria and fungi at 27 oC for 28 days.