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 ofpagP 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.