Studies on Freeze injury in Enterohemorrhagic E. coli 0157

肠出血性大肠杆菌冻伤的研究0157

• 批准号: 10660127
• 负责人: MIYAMOTO Takahisa
• 金额: $ 2.11万
• 依托单位: KYUSHU UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1998
• 资助国家: 日本
• 起止时间: 1998 至 1999
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-10660127/
• 关键词: Escherichia coli O157; freezing injury

Viability of the E. coli O157 has been determined on TSA and CT-SMAC after frozen storage at -20ィイD1゜ィエD1C in various media. The unwashed O157 cells showed the highest viability in saline, though the washed cells showed the lowest viability in the medium. The decrease in viability in water, phosphate buffer and TSB medium was lower in washed cells than in unwashed cells. The decrease in viability was the lowest in 200mM phosphate buffer when E. coli O157 cells were frozen stored in phosphate buffers with various concentration. These results suggest that O157 cells acquire freeze tolerance when it is washed with water.Injury of E. coli O157 cells was largest at pH3 and 3.5. The viability of the cells after frozen storage for 3 days was highest when the cells were frozen in buffers with pH's from 5.5 to 6.5. The viability of the washed cells was higher than that of the unwashed cells. The decrease of the amount of a 7.9 kDa protein of the whole cells was observed after frozen storage in buffers above pH 6. In contrast, a whole cell protein with 12.5kDa increased after frozen storage.The viability was determined both microscopically by using fluorescence dye and plating method. After frozen storage for 3 days at -20ィイD1゜ィエD1C in phosphate buffer (pH 6.5), 70% of the unwashed E. coli lost its ability for colony formation.These results suggest that E. coli O157 cells increase freeze tolerance when the cells are washed with water.

E.大肠杆菌O 157在各种培养基中于-20 ℃冻存后，在TSA和CT-SMAC上进行了测定。未洗涤的O 157细胞在盐水中显示出最高的活力，尽管洗涤的细胞在培养基中显示出最低的活力。在水、磷酸盐缓冲液和TSB培养基中，经洗涤的细胞的活力降低低于未经洗涤的细胞。在200 mM磷酸盐缓冲液中，E. coliO 157细胞冻存于不同浓度的磷酸盐缓冲液中。以上结果提示，O 157细胞经水洗后具有抗冻性。coliO 157细胞在pH 3和3.5时最大。当细胞在pH为5.5至6.5的缓冲液中冷冻时，冷冻储存3天后细胞的活力最高。洗涤细胞的活力高于未洗涤细胞的活力。在高于pH 6的缓冲液中冷冻储存后，观察到全细胞的7.9kDa蛋白质的量减少。冻存后全细胞蛋白质含量增加，分子量为12.5kDa。在磷酸盐缓冲液（pH6.5）中于-20 ℃ D1-D1C冷冻保存3天后，70%的未洗涤E.结果表明，大肠杆菌在体外培养时丧失了集落形成能力。大肠杆菌O 157细胞经水洗后，耐冻性增强。