目的　探讨产毒性大肠杆菌 (ETEC)毒力受环境因素调控的机理。方法　采用ELISA及DNA RNA杂交法观察在不同培养条件下 ,ETEC毒力因子及毒力基因mRNA的表达 ;并且比较加入或不加入DNA解旋酶抑制剂novobiocin和coumermycinA1对ETEC毒力因子及其基因mRNA表达的影响。结果　ETEC肠毒素 (LT和ST)及定居因子 (CFA)表达均与mRNA呈剂量反应关系 ;novobiocin和coumermycinA1对ETEC生长的影响也受细菌培养环境的影响 ;在正常培养条件下 ,novobiocin或coumermycinA1对ETEC的生长有轻微抑制作用 ,毒力的表达也相对较低 ,但在培养环境改变时 ,如 :在novobiocin 2 0 μg/ml或coumermycinA12 μg/ml的作用下 ,LT、ST和CFA的表达均明显增加 ,mRNA的表达也明显增高。结论　环境刺激可能通过影响ETEC染色体DNA毒力调控基因的超螺旋结构而调控ETEC毒力的表达 Objective To investigate the mechanism of toxicity of endotoxin-producing Escherichia coli (ETEC) regulated by environmental factors. Methods The expression of virulence factor and ETEC virulence factors and ETEC virulence genes under different culture conditions were observed by ELISA and DNA-RNA hybridization. ETVD virulence factors and their genes were compared with or without the addition of DNA gyrase inhibitor novobiocin and coumermycinA1 Effect of mRNA expression. Results The expression of ETEC, ST and CFA was dose-response relationship with mRNA. The effects of novobiocin and coumermycinA1 on the growth of ETEC were also affected by the bacterial culture environment. Under normal culture conditions, novobiocin or coumermycinA1 The growth inhibition of ETEC was slight and the virulence was relatively low. However, the expression of LT, ST and CFA in the culture environment were changed under the conditions of novobiocin 20 μg / ml or coumermycin A 12 μg / ml Significantly increased, mRNA expression was significantly increased. Conclusion Environmental stimuli may regulate the expression of ETEC virulence by affecting the supercoiled structure of ETEC chromosomal DNA virulence regulatory genes