Antimicrobial and antibiofilm effects of selenium nanoparticles on some foodborne pathogens

Abstract

Microbial biofilms, which characterized by their resistance to the traditional antimicrobials, are considered as a renewable source of contamination by pathogens. As alternative antimicrobial and antibiofilm agent selenium nanoparticles (SeNPs) were biosynthesized by treatment of 1 mM SeO2 with the free-cell supernatant of Bacillus licheniformis isolated from food wastes. The biosynthesized SeNPs were characterized by their spherical shape with diameter range of 10–50 nm and a well-defined absorption peak at 263 nm in UV–vis spectra. The biosynthesized SeNPs were used to control growth and biofilm formation by six foodborne pathogens including Bacillus cereus, Enterococcus faecalis, Staphylococcus aureus, Escherichia coli O157:H7, Salmonella Typhimurium, and Salmonella Enteritidis. The MIC90 of SeNPs against all tested bacteria was 25 μg/mL, whereas the antibiofilm concentration was 20 μg/mL against all bacteria, except B. cereus. Although the biogenic SeNPs had antimicrobial and antibiofilm effects, they did not show ability to remove the established biofilm up to 50 μg/mL. The concentration of 75 μg/mL showed slight effect on removing the established biofilm. No toxicity on Artemia larvae was demonstrated by SeNPs upto 100 μg/mL. In conclusion, SeNPs produced in the present study can be used as a promising agent for effectively preventing biofilm formation by foodborne pathogens.