Evaluation and Comparison of the antimicrobial activity of Bifidobacterium bifidum and Bifidobacterium infantis as probiotic bacteria against Salmonella enterica serotype Enteritidis

Background: During the last decades, the prevalence of foodborne diseases due to contaminated food as well as demand for natural and healthy foods has increased. Using probiotics for this purpose and for inhibiting growth of food pathogens is an interesting topic.Objective: The aim of this study was to investigate the antibacterial effects of Bifidobacterium bifidum and Bifidobacterium infantis against salmonella enterica serotype Enteritidis by three different methods namely spot on lawn assay, agar well diffusion assay and agar disk diffusion assay and to compare the methods by the means of SPSS program.Material and methods: Supernatant and sediment of the two probiotic bacteria culture was tested in three different assays (spot-on-lawn, well diffusion and disk diffusion) against salmonella.Results: results showed that in all three assays, sediment and supernatant of Bifidobacterium infantis culture had a greater inhibition effect on salmonella than Bifidobacterium bifidum but the difference was not significant from statistical analyses point of view. In this study Well diffusion assay was the best method to identify the antagonism of microorganisms and spot- on lawn method was the worse.2Also in all three methods, the supernatant was significantly more effective than sediment in inhibiting the pathogen.Discussion: This inhibition could be related to metabolites such as Acids, Diacetyle , Hydrogen proxide, Bacteriocins,…produced by probiotics. Better functioning of Well method could be explained by high accuracy and volume of supernatant used in Well method

کلیدواژه ها:

probiotic ، Bifidobacterium infantis ، Salmonella ، Well diffusion assay ، antagonism