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Antimicrobial activity and action mechanism of triglycerol monolaurate on common foodborne pathogens

Zhang, Song, Xiong, Jian, Lou, Wenyong, Ning, Zhengxiang, Zhang, Denghui, Yang, Jiguo
Food control 2019 v.98 pp. 113-119
Candida albicans, Cryptococcus neoformans, Escherichia coli, Listeria monocytogenes, Salmonella Typhimurium, Staphylococcus aureus, antimicrobial properties, bacteria, cell cycle checkpoints, emulsifiers, food pathogens, membrane permeability, minimum inhibitory concentration, pH, plasma membrane, potassium sorbate, sodium benzoate, yeasts
Triglycerol monolaurate (TGML) was widely used as an emulsifier in food, cosmetic and other products, and was generally accepted as safe. In the study, the inhibitory activity of TGML against common foodborne pathogens, Escherichia coli, Salmonella typhimurium, Staphylococcus aureus, Listeria monocytogenes, Candida albicans and Cryptococcus neoformans was investigated with comparison to sodium benzoate and potassium sorbate. The minimum inhibitory concentrations (MIC) of TGML against six pathogens were 0.16, 0.16, 0.08, 0.04, 0.64 and 1.25 mg/mL, the minimum bactericidal concentrations (MBC) were 0.64, 1.25, 0.32, 0.16, 5.0 and 5.0 mg/mL, respectively, both lower than that of sodium benzoate and potassium sorbate. The MIC remained stable when the pH values increased from 3 to 9. Besides, the growth of Staphylococcus aureus and Listeria monocytogenes was almost inhibited for 72 h, whereas the inhibition effect on the rest four strains degraded at 36–48 h and 4–5 days, respectively. The action mechanism of TGML was further studied by detecting plasma membrane permeability, membrane surface damage and the impact of cell cycle and intracellular biomacromolecules synthesis. Results revealed that TGML increased cell membrane permeability, destroyed cell membrane integrity and caused depressions and holes, caused cell cycle arrest and biomacromolecules synthesis inhibition. These results suggest that TGML can effectively exert good inhibitory effect on bacteria and yeast by cell membrane action and intracellular inhibition.