Estudio del efecto de la interacción sinérgica entre nisina y el péptido antimicrobiano producido por Shigella flexneri 2, sobre patógenos alimentarios.

M.F. BALLESTEROS; M.A. DELGADO; M. DE LAS M. PESCARETTI; M.F. TORREZ LAMBERTI

Buenos Aires

Congreso; IV Reunión Conjunta de Sociedades de Biología de la Rep. Argenina y XXVII Jornadas Científicas.; 2020

Bacteriocins are antimicrobial peptides that have antagonistic effects against other organisms. Nisin is the most studied bacteriocin able to inhibit a broad spectrum of food spoilage. Shigella flexneri 2 AC172 strain produce a bacteriocin like peptide that displays antimicrobial activity against E. coli AB1133 strain. In this work we evaluated the synergistic effect produced by the combination of nisin and Shigella flexneri 2 AC172`s cell-free supernatant on different pathogenic strains growth. The antimicrobial activity of these peptides, alone or in combination, against foodborne bacterial pathogens was determined by the minimal inhibitory concentration (MIC) method, followed by determination of the optical density at 600 nm in a microplate reader. For these purpose, a 96-well microplate containing serial double dilutions of nisin, Shigella flexneri 2 AC172`s cell-free supernatant, or different nisin/cell-free supernatant amount combination, were inoculated with a suspension of testing bacterial containing 10 4 ?10 5 CFU/ml. These microplates were then incubated for 24 h at 37°C. The MIC values were used to determinate the Fractional Inhibitory Concentration (FIC) and the FIC index (FICI), which finally defined thesynergistic effect exert by both antibiotic compounds. In this work, we observed a synergistic effect between both bacteriocins, increasing the antibiotic senitivity of pathogenic strains. These natural antimicrobial combinations represent a biotechnological strategy applicable to preservation of the food industry, in order to combat foodborne pathogens that can affect the human health.