高压脉冲电场作用下亚致死酵母的存在与检测

Existence and Detection of Sub-lethal S.cerevisiae Cells Under Pulsed Electric Field Treatment

为探究高压脉冲电场(PEF)对酿酒酵母的灭菌机理,研究了从亚细胞水平揭示PEF处理下的损伤亚致死酵母细胞的存在及产生规律。采用pH7.2的磷酸盐缓冲液(PBS)模拟体系,30 kV/cm电场强度下循环处理100～500μs,通过选择性培养基与非选择性培养基菌落计数对PEF处理前后亚致死酵母细胞进行了研究。结果显示,亚致死酵母的临界渗透压为4%NaCl,PEF处理后,酿酒酵母的亚致死率可达到4.5个对数,亚致死细胞数量达到1.5个对数,且亚致死程度随处理时间的延长而加大。选择性培养基可用于PEF处理过程中亚致死细胞的定量检测。

To explore the sterilization mechanism of Saccharomyces cerevisiae caused by pulsed electric field （PEF）, the existence and production patterns of sub-lethal yeast cells under PEF treatment were revealed. Using phosphate buffer （PBS） at pHT. 2 as model system, S. cerevisiae ceils were processed under 30kV/cm electric field strength from 100 ~s to 500~s. Sub-lethal S. cerevisiae cells were counted respectively after incubation in selective me- dium and non-selective medium. The results showed that the critical osmotic pressure of sub-lethal S. cerevisiae were 4% NaC1. After PEF treatment, S. cerevisiae became to be sub-lethal with reductions to 4.5 Log units, and the num- ber of sub-lethal cell were 1.5 Log, and the degree of sub-lethal increased with the treatment time increased. Selec- tive medium can be used in quantitative detection of sub-lethal cells during PEF treatment.