辣木籽素对单增李斯特菌的抑制作用

Inhibitory Effect of Moringin from Moringa oleifera Seeds on Listeria monocytogenes

摘要:

为了探究辣木籽素对单增李斯特菌（Listeria monocytogenes）的抑制作用，采用牛津杯法、二倍稀释法和生长曲线评价辣木籽素对L. monocytogenes的抑菌活性。通过核酸泄漏和蛋白质泄漏、胞外总糖、PI染色探究辣木籽素对单增李斯特菌细胞膜通透性的影响；运用结晶紫染色、细菌表面疏水性、菌体泳动性及扫描电镜评估辣木籽素对L. monocytogenes生物被膜的影响；采用胞内Ca2+含量和细胞凋亡率分析辣木籽素对单增李斯特菌凋亡的影响。结果表明，辣木籽素对单增李斯特菌具有较强的抑菌活性，其最小抑菌浓度（MIC）为400 μmol/L；经1 MIC辣木籽素处理后的单增李斯特菌生长明显受到抑制，细胞膜损伤率达50.20%，通透性显著增加（P<0.05）；核酸、蛋白质和糖类等大分子物质泄漏量分别是对照组的2.59倍、2.38倍和1.34倍（P<0.05）；与对照组相比，生物被膜形成、细菌表面疏水性、泳动性和粘附性显著降低58.10%、38.00%和68.19%（P<0.05）；胞内Ca2+含量显著上升3.83倍（P<0.01），凋亡率达54.40%。辣木籽素可能通过抑制生物膜、改变细胞膜通透性和促进细胞凋亡而起到抑菌作用。该研究为辣木籽素应用于食品防腐奠定了理论基础。

Abstract:

To investigate the inhibitory effect of moringin on Listeria monocytogenes, the antibacterial activity of moringin against L. monocytogenes was evaluated by the Oxford cup method, the double dilution method, and the growth curve. The effects of moringin on cell membrane permeability of L. monocytogenes were explored through determining nucleic acid leakage and protein leakage, total extracellular sugar, and PI staining. The effect of moringin on L. monocytogenes biofilm was evaluated by crystal violet staining, bacterial surface hydrophobicity, bacterial mobility, and scanning electron microscopy. The effect of moringin on apoptosis of L. monocytogenes was analyzed based on intracellular Ca2+ content and apoptosis rate. The results showed that moringin had a strong antibacterial activity against L. monocytogenes, and the minimum inhibitory concentration (MIC) was 400 μmol/L. The growth of L. monocytogenes was significantly inhibited after the treatment with 1 MIC moringin, with the cell membrane damage rate reaching 50.20% while the permeability significantly increasing (P<0.05). The leakages of macromolecular substances such as nucleic acids, proteins, and carbohydrates were 2.59, 2.38, and 1.34 times that of the control group, respectively (P<0.05). Compared with the control group, the biofilm formation, bacterial surface hydrophobicity, motility, and adhesion decreased significantly (by 58.10%, 38.00% and 68.19%, respectively) (P<0.05). The intracellular Ca2+ content increased significantly (by 3.83 times; P<0.01), and the apoptosis rate reached 54.40%. Moringin may play an antibacterial rolethroughinhibiting biofilm, changing cell membrane permeability and promoting apoptosis. This study lays a theoretical foundation for the application of moringin in food preservation.