丝裂霉素C对溶原性大肠杆菌O157 Stx毒素表达的影响

Effect of Mitomycin C on the Expression of Shiga Toxin from Escherichia coli O157

【目的】确定丝裂霉素C对溶原性大肠杆菌O157中Stx前噬菌体和Stx毒素的诱导作用。【方法】利用丝裂霉素C作诱导剂对8株溶原性大肠杆菌O157进行噬菌体诱导,以MC1061作指示菌采用双层琼脂平板法观察诱导前后的噬菌斑,并采用PCR方法对噬菌体进行鉴定。同时测定8株溶原性大肠杆菌O157经丝裂霉素C诱导前以及诱导8、12、16h这4个阶段滤液中Stx毒素的表达量,毒素表达量采用WST-1细胞毒性检测试剂盒检测Vero细胞存活率。【结果】溶原性大肠杆菌O157经丝裂霉素C诱导后释放大量的Stx噬菌体颗粒。同时诱导后Stx毒素的表达量也显著增加,且随着诱导时间的延长毒素的表达量继续增加,但增加的幅度逐渐减缓。【结论】本研究确定了丝裂霉素C可以诱导溶原性大肠杆菌O157释放Stx噬菌体,同时也增加了Stx毒素的表达,从而增强细菌的毒力。

[Objective] Effect of mitomycin C on the induction of the Stx-converting bacreriophages （Stx phages） and the expression of Shiga toxin （Stx） from Escherichia coli O157 was investigated. [Method] Bacteriophage was induced by mitomycin C from 8 strains of Escherichia coli serotype O157 and plaques were screened by two layers agar assy using the Escherichia coli MC1061 as indicator. PCR was used to identify the Stx phages. The production of Stx toxins which induced from Escherichia coli O157 was simultaneously measured by WST-1 cell proliferation and cytotoxicity assay kit. Toxin expression included four stages （before induction, after induction 8 h, 12 h and 16 h）. [Result] The results of study showed that mitomycin C induced the release of Stx phages and the expression of Stx toxin from Escherichia coli O157 was apparently increased while induced by mitomycin C. The scope of increase was slower with the time of induction. [ Conclusion ]Stx phages＇ release and Stx toxin expression from Escherichia coli O157 may be increased while induced by mitomycin C. Therefore, the pathogenicity of germs will be enhanced.