Short communication: Inhibitory activities of the lantibiotic nisin combined with phenolic compounds against Staphylococcus aureus and Listeria monocytogenes in cow milk

Abstract

We aimed to investigate the antibacterial activities of carvacrol, thymol, eugenol, cinnamaldehyde, and lantibiotic nisin against standard bacterial strains of the milk pathogens Staphylococcus aureus ATCC 25923 and Listeria monocytogenes ATCC 15313 in cow milk. The minimum inhibitory concentrations (MIC) of these substances were recorded. The synergistic effects were also assessed in culture medium (time kill curve) and in a food model (cow milk) during the storage period (4 °C for 6 d) after inoculation with S. aureus and L. monocytogenes individually by combining nisin and the phenolic compounds at proportions of 1/4 + 1/4 the MIC (determined in a previous in vitro assay) in the culture medium and 1/4 + 1/4 of MIC in the food model. Inhibitory activities of nisin and the tested compounds, as well as synergism in the combinations, were found against both bacteria assayed. Bacteriostatic effects were found with all combinations and a significant difference in L. monocytogenes reduction was found compared with the control assays. Thus, the antibacterial activity of nisin combined with phenolic compounds was confirmed against these pathogenic bacteria that are important in the milk industry, or more broadly in food science, with potential applications for milk preservation.

Combined Antilisterial Effects of Barberry Extract, Cinnamaldehyde and Nisin

“…for this reason, in this study we investigate the combined antilisterial activity of CA, nisin and barberry extract in dual combinations to discover possible synergistic effects. Researchers investigated antibacterial activity of nisin and reported 125 µg/ml as MIC value of nisin against L. monocytogenes which is in agreement with the result of our study (8). The antibacterial effects of nisin were indicated against gram-positive food borne bacteria such as Staphylococcus aureus and L. monocytogenes (28).…”

“…For CA, the MIC value against L. monocytogenes was 0.312 µl/ml. In another study, MIC value of CA against L. monocytogenes was 65 µg/ml (8). Other researchers indicated that MIC value of CA against S. aureus was 0.31 mg/ml (33), and 1.56 µl/ml (~0.26 mg/ml) (11), which were similar to that calculated in the present study.…”

“…Recently, Alves et al, investigate the antibacterial activities of four phenolic compounds, carvacrol, thymol, eugenol and cinnamaldehyde combined with nisin against Staphylococcus aureus and L. monocytogenes in cow milk and broth medium. A significant reduction in L. monocytogenes count was found compared with the control group (8). Another study indicated the synergistic interactions of nisin in combination with cinnamaldehyde against Staphylococcus aureus in pasteurized milk (9).…”

“…trend of listeriosis in the last years, the development of new methods for the elimination of the bacterium from food products is necessary. Cinnamaldehyde (CA), a phenolic compound from cinnamon, has been studied for its antimicrobial activity (7)(8)(9)(10). Antimicrobial activity of CA was reported against a wide range of microorganisms.…”

Nisin in Combination with Cinnamaldehyde and EDTA to Control Growth of Escherichia coli Strains of Swine Origin

“…Indeed, considerable work has been conducted to enhance the poor antibacterial activity of nisin toward Gram-negative bacteria (due to the outer membrane of the Gram-negative cell wall that acts as a physical barrier, obstructing access of the peptides to the cytoplasmic membrane). Such strategies have included destabilization of the outer membrane by combining with essential oils that contain aldehydes, terpenes and phenolic compounds [ 26 , 27 ]. Other strategies have involved nisin and chelating agents such as EDTA, which acts by removing Mg 2+ and Ca 2+ ions essential for stabilizing the lipopolysaccharide (LPS) outer membrane of Gram-negative bacteria [ 18 , 28 ].…”