Optimization of Expression Condition of Fusion Gene Encoding Heat-stable Entero-Toxin I and Heat-labile Enterotoxin B Subunit from Enterotoxigenic Escherichia coli

Objective: To identify the recombinant strain containing ST1-LTB fusion gene of Escherichia coli enterotoxin and optimize its expressional condition.Methods: To identify the recombinant plasmid pXSL1 with restriction endonucleases digestion.To detect expressional level of differently conditional ST1-LTB fusion protein by SDS-PAGE.Results: The recombinant expression plasmid pXSL1 contained ST1-LTB fusion gene having positive reading frame.The expression o ptimization result indicated that the ST1-LTB fusion gene expression optimized condition with IPTG induction is culture medium pH 7.5,culture temperature 37℃,joining IPTG to final concentration 0.8mmol/L when the recombinant strain growth density OD600 achieved 0.8,and induction time 5h.The expression level of the ST1LTB fusion proteins were about 34.8% of total cellular protein with IPTG induction by SDS-PAGE and gel system analysis.Conclusion: The ST1-LTB fusion protein is expressed high by recombinant strain BL21(DE3)(pXSL1).This provided experimental data to research productive technique of bivalent genetically engineered vaccine.