Antimicrobial Activity Ofbaccharis Dracunculifoliadc And Its Synergistic Interaction With Nisin Against Food-Related Bacteria

The antimicrobial activities ofBaccharis dracunculifoliaDC essential oil (EO) and hydroalcoholic extract (HE) were evaluated. The EO showed broad antimicrobial activity and its synergistic combination with nisin was tested. Major components of EO were nerolidol, beta-pinene and D-limonene, while artepillin C, rutin and cafeic acid were major phenolics of HE. EO and HE were tested by agar diffusion assay against several strains of bacteria and yeasts, and mixed cultures of bacterial strains. The EO presented the largest spectrum of antimicrobial activity inhibiting all Gram-positive bacteria tested. Yeasts were not inhibited. The effect of EO against mixtures of sensitive and non-sensitive bacteria was tested on milk agar, being the inhibitory effect only observed on mixtures containing susceptible strains. The combination of EO and nisin at 1/2 MIC was evaluated on the growth curve ofStaphylococcus aureus, Bacillus cereus, Listeria monocytogenesandSalmonellaEnteritidis during 24 h at 37 degrees C. The combination EO-nisin was effective and no viable counts ofB. cereus, L. monocytogenesandS. Enteritidis was observed, while the individual antimicrobials caused no inhibition. The counts ofS. aureuswere about 4 log CFU/mL lower in comparison with EO or nisin alone.B. dracunculifoliaDC may be a potential source of natural antimicrobials, and its synergistic effect with nisin would reduce the working concentration, minimizing the organoleptic effects associated with this plant antimicrobial.