月桂酰精氨酸乙酯失活单增李斯特菌的机制研究

Research on the Antibacterial Mechanism of Lauroyl Arginate Ethyl against Listeria monocytogenes

本文拟研究月桂酰精氨酸乙酯(lauroyl arginate ethyl,LAE)对单增李斯特菌(Listeria monocytogenes)的失活机制。采用二倍稀释法测定LAE对L. monocytogenes的最小抑菌浓度(minimum antibacterial concentration,MIC)。通过测定细胞形态、细胞膜完整性、胞内ATP水平、细胞膜电位、细胞表面疏水性及胞内活性氧(reactive oxygen species,ROS)水平等指标,揭示LAE失活L. monocytogenes的作用机制。结果表明,LAE对L. monocytogenes的MIC值为10μg/mL。与未处理组相比,经终浓度为40μg/mL的LAE处理10 min后,L.monocytogenes细胞形态发生明显皱缩,胞外核酸和蛋白质水平分别升高了1.64和15.39倍(P<0.05),表明细胞膜通透性显著增强(P<0.05),且细胞膜发生去极化,细胞表面疏水性显著增强(P<0.05);胞内ATP水平降低了92.40%(P<0.05);胞内活性氧水平升高了77.27%(P<0.05)。此外,添加抗氧化剂谷胱甘肽和N-乙酰-L-半胱氨酸均能显著降低LAE的抑菌活性(P<0.05)。综上表明,LAE能够有效失活L. monocytogenes,这可能与其损伤细胞膜和诱导氧化应激等有关。该研究为LAE在食品保鲜中的实际应用提供了理论依据。

This work aimed to investigate the inactivation mechanism of lauroyl arginate ethyl(LAE)against Listeria monocytogenes.The antibacterial activity of LAE against L.monocytogenes was evaluated by measuring the minimum antibacterial concentration(MIC).Then,the antibacterial mechanism of LAE against L.monocytogenes was investigated by measuring the cell morphology,cell membrane integrity,intracellular ATP level,cell membrane potential,cell surface hydrophobicity,and intracellular reactive oxygen species(ROS)level.The results showed that LAE could effectively inhibit the growth of L.monocytogenes with a MIC value of 10μg/mL.After LAE treatment at a final concentration of 40μg/mL for 10 min,the cell morphology of L.monocytogenes shrank obviously,the levels of extracellular nucleic acid and protein significantly(P<0.05)increased by 1.64-and 15.39-fold,respectively,as compared with the control cells,indicating a significant enhancement of membrane permeability.After LAE treatment at a final concentration of 40μg/mL for 10 min,the cell membrane was depolarized and the cell surface hydrophobicity was significantly enhanced(P<0.05).The intracellular level of ATP decreased by 92.40%(P<0.05),while the intracellular ROS level increased by 77.27%(P<0.05)compared with the control cells.In addition,glutathione and N-acetyl-L-cysteine could significantly(P<0.05)reduce the antibacterial activity of LAE against L.monocytogenes.In summary,LAE can effectively inactivate L.monocytogenes,which may be associated with the damage of cell membrane and oxidative stress.This study provides a theoretical basis for the practical application of LAE in food preservation.