超高压对单增李斯特菌细胞膜的损伤和致死机理

Effect of ultra high pressure on cell membrane destruction and death of Listeria monocytogenes

摘要:

摘要:【目的】研究超高压对病原微生物单增李斯特菌细胞膜损伤的影响。【方法】本文以单增李斯特菌为研究对象，探讨了不同压力处理(100－500 MPa)对单增李斯特菌的灭活作用，利用透射电镜观察高压处理对细菌细胞超微结构的影响，通过紫外分光光度法、原子吸收分光光度法和荧光分光光度法测定高压处理对细菌细胞膜通透性的影响，采用超微量Na+/K+-ATP酶试剂盒测定高压处理对细菌细胞膜Na+/K+-ATP酶活力的影响。【结果】25℃经300、350、400 MPa 压力处理15 min后，单增李斯特菌总数由9.00分别降至5.20、3.27、1.35个对数单位，经450MPa及以上的压力处理后，单增李斯特菌的致死率达到100%。超高压处理对单增李斯特菌的细胞超微结构造成明显的损伤，细胞结构不完整，细胞壁局部被破坏，细胞膜通透性增大，细胞内物质聚合，出现透电子区。由于细胞膜的损伤使得细胞内无机盐离子、紫外吸收物质流出，细胞膜上的Na+/K+-ATPase失活。【结论】超高压处理造成单增李斯特菌细胞形态结构明显损伤，改变细胞膜的通透性，降低细胞膜上Na+/K+-ATP酶活力，最终使得细胞内无机盐离子和胞内大分子物质外流而死亡。

关键词:关键词:超高压，单增李斯特菌，细胞膜损伤

Abstract:

Abstract:［Objective］To study the effect of ultra high pressure (UHP) on the cell membrane of Listeria monocytogenes．［Methods］We treated L． monocytogenes with different hydra high pressure from 100 to 500 MPa at 25℃ for 15 min．Then we determined the rate of cell inactivation by viable cell counts．We compared the morphological changes of treated and untreated cells using transmission electron microscopy (TEM)．We evaluated the membrane permeability by release of potassium ion (K+) or magnesium ion (Mg2+)，UV-absorbing substances and uptake of the fluorescent dye propidium iodide (PI)．We measured these parameters by spectrofluorometry，UV-spectrophotometer and atomic absorption spectrophotometer (AAS)．We used Na+/K+ -ATPase kit to measure the activity of Na+/K+ -ATPase.［Results］The pressure treatment at 300，350 and 400 MPa reduced the population of the bacteria from 9.00 to 5.20，3.27 and 1.35 Log CFU respectively，and no viable cells could be detected at 450 MPa．The structure changes revealed by TEM show that the cell membrane was damaged，the cell wall was breached and the cytoplasm aggregated and a large electron transmission area appeared which bring about the release of UV-absorbing substances，K+ and Mg2+ ions. Besides，the activity of Na+/K+ -ATPase was also decreased by UHP.［Conclusion］UHP could kill L．monocytogenes．

Key words:Keywords: ultra high pressure，Listeria monocytogenes，cell membrane，damage