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目的用几种不同方法处理细菌,观察对比革兰阳性菌与革兰阴性菌存活率的差异,了解革兰阳性菌和革兰阴性菌的生理特征。方法选取金黄色葡萄球菌和大肠埃希菌为代表,等比稀释后观察两组细菌A600值的变化情况及与CFU的关系;经过反复冻融、酸碱处理,计数两组细菌CFU,观察两组细菌存活率差异;使用相同浓度的溶壁酶对两组细菌细胞壁进行裂解,观察两组细菌菌体蛋白释放情况。结果等比稀释两组细菌,A600值及CFU计数并未按等比下降。在无保护剂的条件下反复冻融3次,大肠埃希菌全部死亡,金黄色葡萄球菌尚有16.14%存活。反复冻融7次后金黄色葡萄球菌全部死亡。在有保护剂的条件下反复冻融5次,大肠埃希菌全部死亡,金黄色葡萄球菌尚有22.09%存活。反复冻融13次后金黄色葡萄球菌全部死亡。在不同pH值培养条件下,金黄色葡萄球菌耐受酸碱变化的范围宽,而大肠埃希菌表现出耐酸的特点。经相同浓度溶壁酶作用后,大肠埃希菌菌体蛋白释放量多于金黄色葡萄球菌。结论金黄色葡萄球菌与大肠埃希菌对反复冻融、酸碱及溶壁酶的耐受性不同,可供做细菌学实验时参考。
Objective To treat bacteria by several different methods and observe the difference of survival rate between Gram-positive bacteria and Gram-negative bacteria to understand the physiological characteristics of Gram-positive bacteria and Gram-negative bacteria. Methods Staphylococcus aureus and Escherichia coli were selected as the representative. The changes of bacterial A600 value and the relationship with CFU were observed after equal dilution. After repeated freezing and thawing, acid-base treatment and bacterial CFU counting, The difference of bacterial viability between the two groups was observed. Lysezyme was used to lyse the bacterial cell wall of the two groups, and the release of bacterial cell proteins in the two groups was observed. The results of equal dilution of two groups of bacteria, A600 value and CFU count did not decline at an equal rate. Frozen and thawed three times in the absence of protective agent, Escherichia coli all died, 16.14% of Staphylococcus aureus survived. Staphylococcus aureus died after repeated freezing and thawing seven times. In the protective agent under the conditions of repeated freezing and thawing 5 times, all of Escherichia coli death, Staphylococcus aureus is still 22.09% survived. Staphylococcus aureus died after repeated freezing and thawing for 13 times. Staphylococcus aureus can tolerate a wide range of acid-base changes at different pH values, while Escherichia coli shows acid-fastness. After the same concentration of lywallzyme, Escherichia coli bacterial protein release more than Staphylococcus aureus. Conclusion Staphylococcus aureus and Escherichia coli freeze-thaw, acid-base and lytic enzyme tolerance, for bacteriological experiments for reference.