噬菌体T7溶菌酶工程菌的构建

Construction of Recombinant Strains of Bacteriophage T7 Lysozyme

将噬菌体T7溶菌酶基因克隆到含有可诱导性启动子LacUV 5的表达载体pAR1206中。在没有诱导剂存在情况下,LacUV 5启动子的转录受到抑制。当带有重组质粒的转化菌生长到适当浓度,向培养液中加入0.4mmol/L IPTG,LacUV 5启动子受到诱导,从而使插入的基因高水平表达,并积累大量具有生物活性的溶菌酶。噬菌体T7溶菌酶在大肠杆菌中表达的产量平均约22mg/L。

The Bacteriophage T7 lysozyme gene was cloned in expression vectorpAR 1206 which contains inductive promoter Lac UV5. Promoter isinhibited without inducer, when Strain E.coli (HMS 174)harbouring therecombinant plasmid grown to an optical density, the Lac UV5 promoteris induced by adding 0.4 mmol/L ispropyl β-d-thioga lactoside (IPTG)to growing cultures. So that inserted gene is expressed at high levelsand large amounts of active lysozyme can be accumulated in E.coli theexpression level of T7 lysozyme in E.coli was 10u/mg or about 22 mgper liter of culture.