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本文根据大肠杆菌 (E .coli)K12asd基因两侧序列设计了一对引物 ,用全菌PCR扩增了福氏 2aT32株的asd基因及其两侧序列。对PCR产物的初步测序结果表明 ,在asd基因两端存在BamHI位点。为了防止由PCR扩增带来的差错 ,我们又从福氏 2aT32株染色体中克隆了全长的asd基因。序列分析的结果表明 ,福氏 2aT32株asd基因的序列与E .coliK12的完全一致 ,全长 16 80bp ,其两侧序列也与E .coli具有高度的同源性。这为以asd基因作为靶基因构建痢疾菌的载体宿主平衡致死系统创造了条件。
In this paper, a pair of primers was designed based on the sequence of K12asd gene of E.coli. The asd gene and its two flanking sequences of 2aT32 strain were amplified by whole bacteria. Preliminary sequencing of the PCR product showed that a BamHI site was present at both ends of the asd gene. In order to prevent the error caused by PCR amplification, we cloned the full-length asd gene from chromosome 2aT32. The results of sequence analysis showed that the sequence of asd gene of 2aT32 strain was completely identical with that of E.coliK12, with a total length of 1680bp. The sequences on both sides of the asd gene also had high homology with E.coli. This creates a condition for constructing a balanced host-lethal system of dysentery bacteria by using the asd gene as a target gene.