Combined Antilisterial Effects of Barberry Extract, Cinnamaldehyde and Nisin

Foodborne illnesses, resulting from consumption of contaminated foods, represent a substantial public health threat. Listeria monocytogenes is a foodborne pathogen bacteria and can cause serious problems in human. Because of this reason, Nowadays various compounds are being used to control these bacteria in foods. The aim of this study was to evaluate antilistarial potential of barberry extract, cinnamaldehyde (CA) and nisin, also to discover synergistic effects of dual combination of these compounds againt Listeria monocytogenes in culture medium.
  The antilisterial activity of barberry extract, cinnamaldehyde (CA) and nisin was evaluated using agar well diffusion method and minimal inhibitory concentration (MIC), also Combined antilisterial activity was examined by fractional inhibitory concentration (FIC) and time-kill assays. In agar well diffusion method, nisin (400 IU/ml) and CA (40 µl/ml) produced the largest inhibition zones (20.75±0.25 and 32.0±1, respectively). MIC values of nisin, CA and barberry extract were 25 IU/ml, 0.312 µl/ml and 37.5 mg/ml, respectively. In time kill assay, the combination of nisin with CA in MIC concentration was found the best combination against L. monocytogenes and a 6 log reduction in bacterial count was obtained. The results of this study revealed that nisin and CA have convenient antilisterial activity and combination of these two compounds in MIC concentration showed synergistic effects against Listeria monocytogenes.