Zhang Ying, Zeng Xin-An, Wen Qi-Biao, Li Lin
School of Light Industry and Food Technology, South China University of Technology, Guangzhou 510640, China.
Guang Pu Xue Yu Guang Pu Fen Xi. 2008 Jan;28(1):156-60.
To know the lethal mechanism of microorganisms under pulsed electric field treatment, the relationship between the inactivation of Saccharomyces cerevisiae (CICC1308) cell and the permeability and fluidity changes of its cell membrane treated by pulsed electric field (0-25 kV x cm(-1), 0-266 ms) was investigated. With 1,6-diphenyl-1,3,5-hexatriene (DPH) used as a probe, the cell membrane fluidity of Saccharomyces cerevisiae treated by pulsed electric field was expressed by fluorescence polarization. Results showed that the cell membrane fluidity decreases when the electric flied strength is up to 5 kV x cm(-1), and decreases with the increase in electric field strength and treatment time. The plate counting method and ultraviolet spectrophotometer were used to determine the cell viability and to investigate the cell membrane permeability, respectively, treated by pulsed electric field. Results showed that the lethal ratio and the content of protein and nucleic acid leaked from intracellular plasma increased with the increase in the electric field strength and the extension of treatment time. Even in a quite lower electric field of 5 kV x cm(-1) with a tiny microorganism lethal level, the increase in UV absorption value and the decrease in fluidity were significant. It was demonstrated that the cell membrane fluidity decreases with the increase in lethal ratio and cell membrane permeability. The viscosity of cell membrane increases with the decrease in fluidity. These phenomena indicated that cell membrane is one of the most key sites during the pulsed electric field treatment, and the increased membrane permeability and the decreased cell membrane fluidity contribute to the cell death.
为了解脉冲电场处理下微生物的致死机制，研究了脉冲电场（0 - 25 kV·cm⁻¹，0 - 266 ms）处理酿酒酵母（CICC1308）细胞的失活情况与其细胞膜通透性和流动性变化之间的关系。以1,6 - 二苯基 - 1,3,5 - 己三烯（DPH）为探针，用荧光偏振法表征脉冲电场处理后酿酒酵母的细胞膜流动性。结果表明，当电场强度达到5 kV·cm⁻¹时，细胞膜流动性降低，且随电场强度和处理时间的增加而降低。分别采用平板计数法和紫外分光光度计测定脉冲电场处理后的细胞活力和研究细胞膜通透性。结果表明，致死率以及从细胞内液中泄漏的蛋白质和核酸含量随电场强度的增加和处理时间的延长而增加。即使在电场强度低至5 kV·cm⁻¹且微生物致死水平微小的情况下，紫外吸收值的增加和流动性的降低也很显著。结果表明，细胞膜流动性随致死率和细胞膜通透性的增加而降低。细胞膜的粘度随流动性的降低而增加。这些现象表明，细胞膜是脉冲电场处理过程中最关键的部位之一，细胞膜通透性的增加和细胞膜流动性的降低导致细胞死亡。
