Antibacterial activity of bee propolis samples from different geographical regions of Turkey against two foodborne pathogens, Salmonella Enteritidis and Listeria monocytogenes

The aim of the present study was to investigate the antibacterial activities of 25 propolis samples collected from various geographical regions of Turkey against 2 food-borne pathogens, Salmonella Enteritidis ATCC 13076 and Listeria monocytogenes ATCC 1462. The chemical compositions of ethyl alcohol extracts of the propolis (EEP) samples were determined by gas chromatography coupled to mass spectrometry. The main components of EEP samples were flavonoids, aromatic acid esters, aromatic alcohols, aromatic acids, aliphatic carboxylic acids, terpens, and aliphatic carboxylic acid esters. Antibacterial activities of the EEP samples were tested at 2 different dilutions of 1:10 and 1:100 (v/v). All EEP samples at 1:10 dilution showed high antibacterial activity against the test bacterial strains and no viable bacteria were determined after incubation. The S. Enteritidis strain was found to be resistant toward EEP samples at 1:100 dilution ratios. However, most of the EEP at 1:100 dilution ratios had high antibacterial activity against the L. monocytogenes strain. While some of EEP at 1:100 dilution ratios killed all viable cells of L. monocytogenes, some EEP carried out 1-6 log reductions in the viable cells of this strain. Antibacterial activity of propolis depends on the chemical composition and types of bacteria. The propolis samples had a marked antibacterial action against the gram-positive strain and limited activity against gram-negative one depending on EEP concentration.