The effect of Spearmint, Oregano, and Thyme extracts on biofilm formation by Listeria monocytogenes, Escherichia coli O۱۵۷: H۷, and Salmonella typhimurium.

The production of bacterial biofilms on surfaces related to food processing is of particular importance. Given the health concerns associated with biofilm production on food-related surfaces and the increasing antimicrobial resistance in pathogenic bacteria, the present study aimed to investigate the anti-biofilm effects of oregano, spearmint, and thyme extracts on the biofilms of Salmonella typhimurium, Escherichia coli O۱۵۷: H۷, and Listeria monocytogenes.Spearmint, Oregano, and Thyme plants were freshly prepared, dried, and ground. The hydro and ethanolic extracts of the plants were extracted by soaking. The amount of phenolic compound in the obtained hydro and ethanolic extracts was evaluated using the spectrophotometric method. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of the extracts were determined. The biofilm inhibition and destruction by the extracts were investigated using the microdilution method.The results showed that the highest amount of phenolic compounds among ethanolic and aqueous extracts belongs to oregano and thyme extracts, respectively. Also, the results showed that the lowest effective concentration of the extracts on L. monocytogenes was by thyme aqueous extract with MIC and MBC of ۱.۸ and ۲%, respectively, and for oregano ethanolic extract was ۱.۲ and ۱.۴%. The most significant biofilm-inhibiting effect on L. monocytogenes, S. typhimurium, and E. coli O۱۵۷: H۷ was observed by the thyme aqueous extract and oregano ethanol extract. Moreover, the highest amount of biofilm destruction was achieved by the thyme aqueous extract and oregano ethanol extract. The results of the present study indicate that aqueous and ethanolic extracts of spearmint, oregano, and thyme plants have inhibitory and destructive effects on biofilm formation by pathogenic bacteria. Therefore, these antimicrobial compounds can be used to control and prevent biofilm formation in food industries.

کلیدواژه ها:

biofilm ، Salmonella typhimurium ، Listeria monocytogenes ، Escherichia coli O۱۵۷: H۷ ، Plant extracts