目的 研究pagP基因缺失对禽致病性大肠埃希菌（Avian pathogenic Escherichia coli，APEC）外膜特性的影响。方法 采用最低抑菌浓度（MIC）试验探索pagP基因缺失对菌株生物被膜通透性的影响；通过菌体自聚合试验、外膜疏水性试验以及生物被膜形成条件，分析pagP基因缺失对生物被膜形成能力的影响，并在扫描电镜下观察细菌生物被膜形态。结果 pagP基因缺失后，菌株MIC降低，菌株的外膜通透性增强且菌体自聚合能力显著增强（P < 0.01），其中红霉素和氨苄西林的MIC分别为7 和20 μg/mL，菌株自聚合能力为87.89%；pagP基因缺失对菌株外膜疏水性无显著影响，疏水性仅为5.337%；随着细菌在LB培养基中静置培养时间的延长，生物被膜形成量增多；pagP基因缺失株的生物被膜形成能力高于野生株。结论 pagP基因缺失可使APEC外膜特性发生改变，生物被膜形成能力增强。
Objective To study the effect of pagP gene deletion on outer membrane characteristics of avian pathogenic Escherichia coli(APEC).Method The minimal inhibitory concentration (MIC) experiment was used to explore the effect of pagP deletion on the permeability of outer membrane of strain. Autoaggregation experiment, outer membrane hydrophobicity test, and analysis of biofilm-forming conditions of strain were performed to understand the influence of pagP deletion on biofilm-forming ability. The biofilm morphology was observed by scanning electron microscopy.Result The MIC of strain decreased after the deletion of pagP gene, the outer membrane permeability of strain increased, and the autoaggregation ability of strain increased significantly (P < 0.01). The MICs of erythromycin and ampicillin were 7 and 20 μg/mL respectively. The autoaggregation ability of strain was 87.89%. The deletion of pagP gene had no significant effect on the hydrophobicity of outer membrane of strain, and the hydrophobicity was only 5.337%. The amount of biofilm increased with the increase of time when the strain was cultured in LB medium. The strain with pagP deletion had higher biofilm-forming ability than wild strain.Conclusion The deletion of pagP gene can change the characteristics of outer membrane of APEC and enhance the biofilm-forming ability.