Towards understanding the antagonistic activity of phytic acid against common foodborne bacterial pathogens using a general linear model

Abstract

The increasing challenge of antibiotic resistance requires not only the discovery of new antibiotics, but also the development of new alternative approaches. Therefore, in the present study, we investigated for the first time the antibacterial potential of phytic acid (myo-inositol hexakisphosphate, IP6), a natural molecule that is 'generally recognized as safe' (FDA classification), against the proliferation of common foodborne bacterial pathogens such as Listeria monocytogenes, Staphylococcus aureus and Salmonella Typhimurium. Interestingly, compared to citric acid, IP6 was found to exhibit significantly greater inhibitory activity (P<0.05) against these pathogenic bacteria. The minimum inhibitory concentration of IP6 varied from 0.488 to 0.97 mg/ml for the Gram-positive bacteria that were tested, and was 0.244 mg/ml for the Gram-negative bacteria. Linear and general models were used to further explore the antibacterial effects of IP6. The developed models were validated using experimental growth data for L. monocytogenes, S. aureus and S. Typhimurium. Overall, the models were able to accurately predict the growth of L. monocytogenes, S. aureus, and S. Typhimuriumin Polymyxin acriflavine lithium chloride ceftazidime aesculin mannitol (PALCAM), Chapman broth, and xylose lysine xeoxycholate (XLD) broth, respectively. Remarkably, the early logarithmic growth phase of S. Typhimurium showed a rapid and severe decrease in a period of less than one hour, illustrating the bactericidal effect of IP6. These results suggest that IP6 is an efficient antibacterial agent and can be used to control the proliferation of foodborne pathogens. It has promising potential for environmentally friendly applications in the food industry, such as for food preservation, food safety, and for prolonging shelf life.

Fig 1. Minimum inhibitory concentration of IP6 (□) and CA (■) against indicator strains (L. monocytogenes ATCC 19117, S. aureus ATCC 6538, S. Typhimurium ATCC 14028, P. aeruginosa ATCC 49189 and E. coli ATCC 8739.).

Values represent the means of triplicate experiments with comparable results.

Fig 2. Diameter inhibition zone of IP6 against L. monocytogenes ATCC 19117(□), S. aureus ATCC 6538 (■) and S. Typhimurium ATCC 14028(↘).

Values represent the means of triplicate experiments with comparable results.

Fig 3

Influence of the dose of IP6 on the growth of L. monocytogenes ATCC 19117 (a), S. aureus ATCC 6538(b) and S. Typhimurium ATCC 14028 (c) in vitro using a linear model (ANOVA).