Objective To discuss the acid resistance of Escherichia coli O157:H7 preliminarily. Methods The survival ability of Escherichia coli O157:H7 under different pH conditions was observed by the dilution coating plate count method, and the morphological changes of the bacteria under acid stress were observed by scanning electron microscope. Results When the pH was between 5. 0 and 7. 0, the growth of Escherichia coli O157:H7 was good. When the pH was less than 4. 0, its growth was restrained, especially when pH dropped below 2. 0, Escherichia coli O157:H7 was completely unable to grow. It indicated that Escherichia coli O157:H7 was strong in acid resistance and could resist the effects of acidic environment. The scanning electron micrograph showed that Escherichia coli O157:H7 had corresponding changes in the morphology of the bacteria under different pH conditions, and its cell morphology changed from the form of bacillus to a short rod or a dull circular shape with the acid enhancement of the medium. Conclusion This study determined the survival and reproduction ability of Escherichia coli O157:H7 under different acidic conditions, which is helpful for further understanding its acid tolerance, so as to provide references for formulating control programs and measures.%目的 对大肠杆菌O157:H7耐酸性进行初步探讨.方法 通过稀释涂布平板计数法观察大肠杆菌 O157:H7在不同的pH生长条件下的存活能力和利用电镜扫描法观察其在酸胁迫下菌体形态的变化.结果 当pH为5. 0到7. 0之间时,大肠杆菌O157:H7生长状况良好,当pH小于4. 0时,其生长受到抑制,特别是pH降到2. 0以下时,大肠杆菌O157:H7完全不能生长,由此可以说明大肠杆菌O157:H7耐酸性能力较强,可以抵御酸性环境的影响.扫描电镜图显示大肠杆菌O157:H7在不同pH的环境条件下其菌体形态会作出相应的变化, 随着培养基的酸性增强,其细胞形态从长杆菌体形态变成了短杆状或钝圆形态.结论 本研究测定不同酸性条件下大肠杆菌O157:H7的生存和繁殖能力的研究,有利于帮助人们进一步了解其耐酸性,从而为制定防治方案和措施提供参考.
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