Analysis of injury in the function of cytoplasmic membrane of E. coli causedby high-pressure treatment

本研究旨在阐明高压处理对大肠杆菌细胞质膜功能损伤的实质，寻找高压处理食品加工中更有效的灭菌条件。大肠杆菌指数相细胞对高压处理的敏感性明显高于固定相细胞。指数期细胞经75MPa、30 min、37℃的中等高压处理后，在营养液中生长。生长60 ~ 90min后，大部分细胞被拉长至4 ~ 8个细胞长。DAPI染色显示核区分裂。大肠杆菌的recA和sulA突变体在中高压处理下表现相似。这一结果清楚地表明，SOS反应与细胞分裂缺陷无关。其次，利用荧光染料偶联抗FtsZ抗体对8个细胞长左右的细长细胞进行FtsZ环的检测。平均而言，在一个细长的细胞中观察到一个环，在一个细胞的长度从末端开始。这表明高压处理后功能性FtsZ的不足。提示高压处理最敏感的靶点可能是FtsZ蛋白本身。

This study was intented to crarify the entity of injury in the function of Esherichia coli cytoplasmic membrane caused by high-pressure treatment and to find more effective sterilization condition in the high-pressure treatment based food-processing.Exponential phase cells of E. coli were mucn more sensitive to high-pressure treatment than those of stationary phase. After the moderate high-pressure treatment of exponential phase cells at 75MPa, 30 min., 37℃, the treated cells were grown in nutrient broth. After the growth for 60 to 90 min., most of cells were found to be elongated to 4 to 8 cell-length. DAPI staining revealed that nuclear regions were partitioned. The recA and sulA mutants of E. coli behaved similarly in the moderate high-pressure treatment. This results clearly show that SOS response was not involvedin this defect of cell division. In the next place, the presence of FtsZ ring was investigated for the elongated cells of about 8 cell-length by using fluorescent dye-coupled anti-FtsZ antibody. On an average, one ring was observed for a elongated cell at one-cell lenght inside from the end. This result shows the shortage of functional FtsZ after high-pressure treatment. It is suggested that the possible most sensitive target of high-pressure treatment is FtsZ protein itself.