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

本研究旨在明确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。对指数期细胞进行75 Mpa、30min、37℃的中高压处理后，在营养肉汤中培养。培养60~90min后，大部分细胞伸长到4~8个细胞长度。DAPI染色显示核区被分割。大肠杆菌的recA和sula突变体在中等高压处理中表现相似。这一结果清楚地表明，SOS反应不参与细胞分裂的这种缺陷。其次，用荧光染料偶联的抗FtsZ抗体对约8个细胞长度的细长细胞的FtsZ环的存在进行了研究。平均而言，一个细长的细胞在从末端到内部的一个细胞长度上观察到一个环。这一结果显示了高压处理后功能性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.