中文摘要：

以1株染色体上的5个rRNA操纵元（rrnA、rrnD、rrnE、rrnG和rrnH）被敲除的大肠杆菌（Escherichia coli）菌株SQ88为出发菌，运用入Red同源重组系统和卡那霉素抗性基因筛选重组子，并利用抗性基因两端的FRT位点通过位点专一性重组将抗性基因去除，最终成功构建了1株仅具有单拷贝rRNA操纵元（rrnB）的E．coli菌株——SQ88C。试验结果发现，此菌株并未出现明显的生长障碍，其生长速率和rRNA／蛋白值与出发菌株SQS8相比有所下降，但并不显著。从而证明了单拷贝rRNA操纵元在一定条件下能够满足大肠杆菌正常生长的需要，也为在大肠杆菌及其他菌株中快速精确地构建多rRNA基因缺失菌株提供了有益的参考，并可望在16SrRNA基因突变研究等方面发挥一定的作用。

英文摘要：

The Escherichia coli strain SQ88 was selected as the target strain, to which five of rRNA operons （rrnA, rrnD, rrnE, rrnG and rrnH） were sequentially inactivated using λ Red recombination system. Using Red recombination system, SQ88C, a strain just carrying one copy of rRNA operon （rrnB） was constructed by screening Kan resistance mutant. The Kan resistant gene between two FRT recognizing sites was then eliminated designedly. The manipulated strain SQ88C showed no obvious defects in growth rates, and the rRNA/protein ratio remained as the target one. The results suggested that the one copy of rRNA operon could support the growth of E. coli in normal conditions. It indicated that Red in vivo recombination was a convenient method to construct rRNA genes deletion strain. This strain is of potential in the research of 16S rRNA gene mutations.