Activity of the plant-derived peptide Ib-AMP1 and the control of enteric foodborne pathogens

Consumer demand for use of fewer traditional antimicrobial agents in foods has driven research interest in development of plant based antimicrobial agents for use in food and food processing. The purpose of the present study was to investigate Ib-AMP1, a plant antimicrobial peptide (pAMP), isolated from seeds of Impatiens balsamina. Activity against foodborne pathogens, cytotoxicity to select human cells, and residual activity were investigated. Results of these experiments aid in determining the feasibility of using Ib-AMP1 as an antimicrobial agent to control foodborne pathogens. Ib-AMP1 exhibited bactericidal activity against Staphylococcus aureus, Escherichia coli O157:H7, Salmonella enteric serovar Newport, Pseudomonas aeruginosa, and Bacillus cereus. When tested using low (103 CFU mL−1) and intermediate (106 CFU mL−1) E. coli O157:H7 cell numbers, an approximately 1.46–2.69 log reduction in cell numbers occurred at the 1× and 2× minimum inhibitory concentration (MIC) of Ib-AMP1. The results suggest that a concentration of Ib-AMP1 several fold greater than the MIC would be required in foods with high levels of commensal bacteria. A separate experiment showed no residual activity of Ib-AMP1 was apparent following interaction of the peptide with bacteria. Results of the MTS [3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium] cell proliferation assay indicated that Ib-AMP1 at 200, 400 and 600 μg mL−1 inhibited by 50% cell proliferation activity of Hep G2, FHs 74 Int and HT29 cells, respectively. Taken together, these data suggest that Ib-AMP1 has potential application as an antimicrobial agent in food systems.