脉冲电场对沙门氏菌细胞膜流动性的影响及其机理

摘要

研究了脉冲电场作用对鼠伤寒沙门氏菌Salmonella Typhimurium的杀菌效应及其膜通透性的影响,并结合拉曼光谱技术分析了不同脉冲处理时间对沙门氏菌磷脂构象的影响.结果表明:随着脉冲电场能量的不断输入,沙门氏菌的灭活对数不断增加,且细胞膜的通透性也随之增大;此外,随着脉冲处理时间的延长,沙门氏菌磷脂拉曼峰的峰值比I1139/I1082呈现出先增大后减小的趋势,但是均比未经脉冲电场处理的峰值比要高(P＜0.05).这说明脉冲电场作用能够增加沙门氏菌磷脂的C—C全反式构象的数目,同时减少了C—C扭曲构象数目;但是,随着脉冲处理时间的延长,峰值比I2874/L862也随之增大(P＜0.05),这意味着脉冲电场作用能够有效增大沙门氏菌磷脂C—H的侧向堆积程度,从而导致了磷脂脂链的有序程度增加和细胞膜流动性的减弱.因此,脉冲电场作用能够增大细胞膜的通透性和降低细胞膜流动性,最终会引起细胞损伤或者死亡.这为脉冲电场作用下微生物的灭活机理研究提供了一定的理论依据.%In the investigation,the effects of the pulsed electric field (PEF) treatment on the survival ratio and cytomembrane permeability of Salmonella Typhimurium are discussed,and the effect of the PEF treatment time on the phospholipid conformation of S.Typhimurium is also analyzed by using the Raman spectra.The results show that (1) as the energy of PEF inputs continuously,the cell viability decreases and the cytomembrane permeability increases;(2) with the increase of the PEF treatment time,the peak value ratio of the Raman spectra of S.Typhimurium phospholipid,namely II 139/I1082,first increases and then decreases,and it is always higher than that without PEF treatment (P ＜ 0.05),which indicates that the PEF treatment can increase the number of the all-trans conformation of C—C and decrease the number of the gauche conformation of C—C;and (3) as the PEF treatment time increases,I2874/I2862 increases (P ＜ 0.05),which means that the PEF treatment increases the lateral chain interaction of C—H and thus results in the increase of the intrachain order of phospholipid molecules and the decrease of the cytomembrane fluidity of S.Typhimurium.Therefore,it is concluded that the PEF treatment can cause cell damage or cell death by increasing the cytomembrane permeability and decreasing the cytomembrane fluidity.This investigation provides a theoretical basis for the mechanism research of inactivating micro-organisms with the PEF treatment.