Fir (Abies alba Mill.) Honeydew Honey Inhibits Growth and Adhesion of Campylobacter jejuni In Vitro

This study investigated the physicochemical properties of fir (Abies alba Mill.) honeydew honey (FHH) and its biological activity against the leading foodborne bacterium Campylobacter jejuni. Antibacterial activity, bacterial growth and anti-adhesion tests were performed in Mueller Hinton (MH) broth and cow's milk used as a food model. FHH from the mountainous region of Croatia showed antibacterial activity against C. jejuni in MH broth and milk, with the minimal inhibitory concentration (MIC) values ranging from 12.5 to 50 mg/mL. A transmission electron microscopy (TEM) analysis of C. jejuni cells showed severe cellular damage after exposure to the tested honeydew honey. FHH in concentrations of 3 and 5% (w/v) inhibited growth and prevented adhesion to the polystyrene surface at a concentration of 25 mg/mL or lower of the bacterium C. jejuni in MH broth and milk. The anti-adhesion effect was more pronounced in the milk than in the MH broth. These results suggest that FHH has potent antibacterial activity against C. jejuni due to its particular physicochemical properties.