用限制性核酸内切酶ＥｃｏＲＩ和ＨｉｎｄⅢ双酶切含大肠杆菌肠毒素ＳＴ１—ＬＴＢ融合基因的质粒ｐＸＳＬＴ１，回收０．８４ｋｂ的ＳＴ１—ＬＴＢ融合基因，再将载体ｐＥＴ—２８ｂ（＋）用ＥｃｏＲⅠ和ＨｉｎｄⅢ双酶切，然后将其与ＳＴ１—ＬＴＢ融合基因连接，转化至受体菌ＢＬ２１（ＤＥ３）中。经ＥｃｏＲⅠ、ＨｉｎｄⅢ、ＢａｍＨⅠ酶切反应鉴定重组子质粒，得到了理想重组质粒ｐＸＥＴ－ＳＬＴ１。重组菌株ＢＬ２１（ＤＥ３）（ｐＸＥＴＳＬＴ１）经ＩＰＴＧ诱导后，其表达产物经ＳＤＳ—ＰＡＧＥ和ＥＬＩＳＡ检测，结果表明重组菌株可以高效表达ＳＴ１—ＬＴＢ融合蛋白，该融合蛋白占菌体总蛋白的３３．２１％，而且无天然ＳＴ１生物毒性 The plasmid pXSLT1 containing the E. coli enterotoxin ST1-LTB fusion gene was digested with restriction endonucleases EcoRI and HindIII to recover the 0.84kb ST1-LTB fusion gene, and then the vector pET-28b (+) was digested with EcoRI and EcoRI Hind Ⅲ double digestion, and then with ST1-LTB fusion gene, transformed into the recipient bacteria BL21 (DE3). After digestion with EcoRⅠ, HindⅢand BamHⅠ, the recombinant plasmid was identified and the recombinant plasmid pXET-SLT1 was obtained. The expressed product of recombinant strain BL21 (DE3) (pXETSLT1) induced by IPTG was detected by SDS-PAGE and ELISA. The results showed that the recombinant strain could express ST1-LTB fusion protein efficiently, which accounted for 33.21 %, And no natural ST1 biological toxicity