The effect of nisin on biofilm-forming and pathogenic bacteria using micro titer plate method

Some of pathogenic and food spoilage bacteria may attach on food contact surfaces and form biofilms, which is the sources of food contaminations and distribution of diseases caused by these bacteria. Nisin is a peptidic bacteriocin, which used for biological control of microbial biofilm formation. Also, nowadays, nisin is used in combination with packaging materials to protect food products from contamination with pathogenic bacteria and spoilage. The aim of this study was to assess the effect of different concentrations of nisin on biofilm-forming bacteria. In this experimental research, using micro titer plate method, the effect of different concentrations of nisin on Salmonella enteritidis, Listeria monocytogenes and Staphylococcus aureus was investigated. Using ELISA reader and triphenyl tetrazolium chloride (TTC), the reduction of biofilm-forming bacteria and bactericidal effect of nisin were determined. Data were analyzed by ANOVA and Tukey-Kramer tests, using Minitab software. The results indicated that nisin, in permissive concentration (4´103 IU/ml), is more effective on S. enteritidis biofilm than on L. monocytogenes and S. aureus biofilms with the percentages of 87%, 57%, and 30%, respectively (P<0.05). The finding of this study showed tat increase upper that permissive concentration of nisin isn’t effective on the amount of bacteria or bactericidal effect, however, in permissive concentration has more effect in deletion of bioflm bacteria (S. enteritidis).