Studies on Freeze injury in Enterohemorrhagic E. coli 0157

E的可行性。coli O157 has been determined on TSA and CT-SMAC after frozen storage at-20 D1 D1C in various media。未清洗的O 157细胞显示了盐水中最高的活力，而清洗的细胞显示了中间最低的活力。水、磷酸盐缓冲区和TSB介质中的活性降解比未洗涤的细胞中的活性低。E.在200毫米磷酸盐缓冲液中的降解率最低。大肠杆菌O 157细胞在不同浓度下储存了冰冻的磷酸盐缓冲液。这些结果建议O 157细胞获得冻结的耐受性，当它被水冲洗时。大肠杆菌O 157细胞的pH值为3和3.5。在冷冻储存3天后，细胞的活力最高，当缓冲液中的pH值从5.5到6.5。“被洗涤的细胞的可行性高于那些被洗涤的细胞的可行性。”整个细胞的7.9 kDa蛋白质量的减少在缓冲液中观察到pH值为6的冷冻储存后。在对比度下，一个完整的细胞蛋白在冷冻储存后增加了12.5 kDa。利用荧光染料和平板方法，微观上确定了两者的可行性。After frozen storage for 3 days at-20-D1 D1C in phosphate buffer （pH6.5），70% of the unwashed E.大肠杆菌对结肠形成的影响，这些结果建议E.。当细胞被水冲洗时，大肠杆菌O 157细胞会冻结耐受性。

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.