用生物素标记DNA探针检测和计数食品中产ST大肠杆菌

Detection and Enumeration of Enterotoxigenic Escherichia coli in Foods with Biotinylated DNA Probe

将人工污染产ST大肠杆菌的鲜猪肉、鸡蛋和牛乳稀释液接种到铺在LB琼脂表面的硝酸纤维素膜上,经37℃6～10h培养和严格的去蛋白和RNA处理后,用生物素标记的编码大肠杆菌耐热肠毒素的DNA片段作为基因探针,检测了污染食品中的产ST大肠杆菌.本法具有高度特异性,其敏感性为100个细菌/g.

DNA fragment encoding a heat-stable enterotoxin of Escherichin coli was labelled with Bio-11-dUTP and used as a gene probe. Three kinds of food, meat, egg and milk were artificially contaminated with enterotoxigenic Escherichia coli, which were diluted in varying ratios and inoculated on LB agar with nitrocellulose filter membrane. After incubation for 6-10 h at 37℃and strict deletion treatment of protein and RNA, the colony hybridization was performed for detecting and counting the contaminated enterotoxigenic E. coli with the biotinylated DNA probe. The results indicated that the probe is highly specific and its sensitivity is 100 cells/g.