产肠毒素性大肠杆菌(ETEC)是幼畜、婴幼儿及旅游者腹泻的重要病原菌之一。作者以大肠杆菌pSLM004菌株为始发菌株,利用合成的一对与ST_1基因特定序列相匹配的引物,通过PCR扩增出了ST_(1b)基因。该基因片段扩增物(150bp)经适当方法纯化,与克隆载体pUC18的HlincⅡ位点平端连接,转化到受体菌JM101中。利用氨苄青霉素(Ap)抗性作为压力选择标志以及LacZ基因插入失活显色反 Enterotoxigenic Escherichia coli (ETEC) is one of the important pathogens of diarrhea in young animals, infants and tourists. In this paper, we used the Escherichia coli strain pSLM004 as an initial strain to amplify the ST_ (1b) gene by PCR using a pair of synthetic primers that match the specific sequences of the ST_1 gene. The gene fragment amplified (150bp) was purified by appropriate methods and ligated into the HlincII site of the cloning vector pUC18, and transformed into the recipient strain JM101. Ampicillin (Ap) resistance as a marker of pressure selection and LacZ gene insertion inactivation of chromogenic reaction