中文摘要：

目的 通过Red同源重组法构建qseC基因缺失的大肠杆菌突变株,探讨qseC基因对大肠杆菌运动能力的影响.方法 PCR扩增两翼与目的基因上下游同源、含有氯霉素抗性基因片段,电击转化入大肠杆菌MC1000,在Red同源重组酶作用下,用含同源臂的氯霉素抗性片段置换目的 基因qseC,并利用FLP位点专一性重组将氯霉素抗性基因删除.测定qseC基因缺失株运动能力的变化.结果 qseC基因已被成功敲除.在LB培养基中,qseC基因缺陷株的生长状况与亲株无明显差异.MC1000与MC1000qseC基因缺失株运动圆环的直径分别为（6.10±0.36）mm和（3.20±0.53）mm（P〈0.01）.结论 成功构建大肠杆菌qseC基因缺失突变株,且qseC基因对细菌运动能力具有重要调控作用.

英文摘要：

Objective To construct a qseC-deleted mutant strain of Escherlchla coll by using Red recombination and to study the motility of qseC gene in the mutants. Methods The chlorarnphenicol-resistant gene flanked by homologues of target genes was amplified by PCR and electro-transformed into E. coli MC1000. When induced by L-arabinose, the plasmid pKD46 could express three recombinant proteins of k -prophage, which led to the replacement of target gene （qseC） with chloramphenicol-resistant gene. Then the chloramphenicol-resistant gene was eliminated by FLP-promoted recombination events. The motility of wild-type and mutant strain was detected. Results The qseC-deleted mutant of E. coli was confirmed by various PCR. Gene qseC was completely deleted. There was no significant difference in growth ability between the qseC mutant strain and the wild-type strain MC1000. The sizes of motility halos was （6.10 ± 0.36） mm and （3.20± 0.53） mm, respectively. Conclusion The qseC-deleted mutant of E. coli was constructed successfully, and the qseC gene plays an important role in regulation of motility in Eseherichia coli.