Inhibition of Salmonella typhimurium Growth by ε-Poly-Lysine Hydrochloride and Its Consequent Use in Wet Rice Noodles
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Abstract:
Here, to investigate the inhibitory effect of ε-poly-lysine hydrochloride (ε-PLH) on the growth of Salmonella typhimurium, the minimum inhibitory concentration (MIC) was determined and the growth curve was plotted. The effect of ε-PLH on the cell membrane of S. typhimurium was investigated by evaluating propidium iodide (PI) infiltration and intracellular macromolecule leakage. The effects of ε-PLH on oxidative stress and energy metabolism in S. typhimurium were explored by measuring the intracellular reactive oxygen species (ROS) levels, superoxide dismutase (SOD) and ATPase activities, and ATP content. The results revealed that ε-PLH exhibits robust antibacterial properties in the context of S. typhimurium, with an MIC of 128 μg/mL. Further, ε-PLH was found to effectively inhibit the growth of S. typhimurium. Following treatment with ε-PLH at the MIC, the integrity of the S. typhimurium cell membrane was lost, leading to changes in cell membrane permeability and excessive accumulation of ROS. After 6 h of treatment, the levels of nucleic acid leakage and ROS were 2.45 and 1.99 times higher than those in the control group. Further, compared to the control group, the SOD activity, ATPase activity, and ATP content decreased by 29.60, 10.00, and 67.63%, respectively, in the ε-PLH-treated group. ε-PLH treatment affected the cell membrane of S. typhimurium; this caused oxidative damage and disruption of the intracellular energy balance, ultimately leading to impaired physiological functions and death in S. typhimurium. Furthermore, treatment of wet rice noodles with ε-PLH revealed that ε-PLH still exhibited an antibacterial effect against S. typhimurium and had a good fresh-keeping effect. In conclusion, ε-PLH exhibits promising potential with respect to the control of Salmonella contamination in food.
