中文摘要：

目的 构建噬菌体AB3裂解酶LysAB3原核表达载体，测定LysAB3对鲍曼不动杆菌的抗菌活性。 方法 PCR扩增LysAB3基因,以pET28a（＋）为载体构建重组质粒，在大肠杆菌BL21（DE3）中表达LysAB3，金属离子螯合亲和层析法纯化重组蛋白。检测LysAB3的抗菌力、裂解谱、作用的最佳pH和温度，以及对细胞壁肽聚糖的降解力。 结果 扩散法表明LysAB3对40株鲍曼不动杆菌均有抗菌作用，并可降解其肽聚糖。LysAB3作用的最佳pH为7，最佳温度为25 ℃。经LysAB3作用后的鲍曼不动杆菌，在扫描电镜下可见菌体表面粗糙、皱缩，部分裂解为碎片。 结论 噬菌体AB3裂解酶LysAB3对鲍曼不动杆菌具有明显的抗菌活性。

英文摘要：

Objective To construct a prokaryotic expression vector of bacteriophage AB3 endolysin （LysAB3）, and to investigate the antibacterial activity of LysAB3 against Acinetobacter baumannii. Methods LysAB3 gene was synthesized and inserted into vector pET28a（＋） to construct recombinant expression plasmid pET28a-LysAB3. After expression in E. coli BL21 （DE3） and purification with Ni2＋-NTA Sepharose, we determined the antibacterial activity, lysis spectrum, and optimal pH value and temperature of LysAB3. The degradation against peptidoglycans in the cell wall was analyzed. Scanning electron microscopy was used to observe the cell morphology of Acinetobacter baumannii exposing to LysAB3. Results The gel diffusion assay showed that LysAB3 had bactericidal effects against 40 strains of Acinetobacter baumannii, and it was also able to degrade Acinetobacter baumannii peptidoglycan. Of LysAB3 effects, the optimal pH value is 7, and the optimal temperature is 25℃. LysAB3-treated Acinetobacter baumannii exhibited significant abnormalities, including deep roughening of cell surface, collapse of cell structure and cell debris. Conclusion Bacteriophage AB3 endolysin has significant antibacterial activity against Acinetobacter baumannii.