大肠杆菌磷酸果糖激酶基因在极端嗜酸性氧化硫硫杆菌中的表达

构建了含大肠杆菌磷酸果糖激酶(EC 2.7.1.11)基因pfkA的重组质粒pSDK1，利用大肠杆菌pfk缺陷株筛选含目的基因的重组质粒，通过接合转移的方式将其导入氧化硫硫杆菌TtZ2中，接合转移频率达2.6×10-6。重组质粒在TtZ2中有较好的稳定性，在无选择压力条件下传代50次基本保持稳定(重组质粒保留68%以上)。酶活性测定、SDSPAGE及RTPCR结果表明，pfkA基因在氧化硫硫杆菌中得到表达，但其表达水平低于大肠杆菌。葡萄糖可促进含pSDK1的氧化硫硫杆菌TtZ2的生长，而对照菌株的生长则未受明显影响，说明重组菌可部分利用葡萄糖作为碳源生长。

Expression of Phosphofructokinase Gene from Escherichia coli K-12 in Obligately Autotrophic Bacterium Acidithiobacillus thiooxidans

A plasmid pSDK-1 containing the Escherichia coli phosphofructokinase-1 (EC 2.7.1. 11) gene (pfkA) was constructed and transferred into Acidithiobacillus thiooxidans Tt-Z2 by conjugation. The transfer frequency of plasmid from E. coli to Tt-Z2 was 2.6 x 10(-6). More than 68% of Tt-Z2 cells carried the recombinant plasmids after being cultured for 50 generations without selective pressure, which showed that pSDK-1 was maintained consistently in Tt-Z2. The pfkA gene from E. coli could be expressed in this obligately autotrophic bacterium but the enzyme activity (14 U/g was lower than that in E. coli (K-12: 86 U/g; DF1010 carrying plasmid pSDK-1: 97 U/g). In th presence of glucose, the Tt-Z2 transconjugant consumed glucose leading to a better growth yield.