The Antibacterial Activity of Barberry Root and Fennel Seed Extracts Individually and in Combination with Nisin and Sodium Diacetate Against Escherichia coli O157:H7

One of the most important health challenges is to deal with infectious diseases due to their high prevalence. Since resistance of pathogens to antimicrobial compounds is rising, more studies are performed to develop new antimicrobial agents. Herbs are one of the best sources to achieve the goal.

The current study aimed at examining the possible antibacterial activity of the barberry root and fennel seed extracts individually and in combination with sodium diacetate and nisin against Escherichia coli O157:H7.

Extract of the barberry root and fennel seed were prepared by soaking in ethanol 80% and analyzed by high-performance thin-layer chromatography and gas chromatography-mass spectrometry, respectively. Antimicrobial activity of the extracts was detected by disk diffusion and broth microdilution methods in triplicate.

Nisin showed the highest antibacterial activity against E. coli O157:H7 followed by the extracts of barberry root and fennel seed, and sodium diacetate. The data were consistent with the results of the disk diffusion test. Moreover, a significant difference was observed between antibacterial activity of nisin and sodium diacetate individually, and in combination with the extracts.

The results of the current study showed that the inhibitory effects of sodium diacetate and nisin combined with barberry root and fennel seed extracts were higher compared to their individual effects; it leads to the application of lower amounts of sodium diacetate and nisin in combination with herbal extracts and highly prevents their individual side effects such as toxicity and organoleptic changes.