Antimicrobial synergistic effects of linolenic acid in combination with preservatives against food-borne bacteria

Antimicrobial effects of linolenic acid in combination with preservatives (sodium benzoate, potassium sorbate, citric acid. tartaric acid) against food-borne bacteria such as Bacillus cereus, Escherichia coli O157:H7, Salmonella Enteritidis, Salmonella Typhimurium, Staphylococcus aureus, and Vibrio parahaemolyticus were determined. When B. cereus and S. aureus were treated with 10 and 40 ppm linolenic acid, and 100 ppm each of sodium benzoate, citric acid or tartaric acid, viable cell numbers were reduced by 2-5 and 3-6 log scale compared with those of the control, respectively. When linolenic acid was added to B. cereus at the above level, adenosine triphosphate (ATP) concentration of extracellular fluid drastically increased to 0.125 muM, compared with that of the control (0.047 muM). Combined effects of linolenic acid with preservatives (0.147-0.172 muM) were higher than that with linolenic acid alone. Intracellular ATP concentration (0.266-0.386 muM) decreased compared with that of the control (0.805 muM). Results reveal linolenic acid combined with preservatives has strong antimicrobial activity against B. cereus and S. aureus. Linolenic acid combined with preservatives showed stronger antimicrobial activity than when used alone.