Outer Membrane Protein F Is Involved in Biofilm Formation, Virulence and Antibiotic Resistance in .

In some Gram-negative bacteria, encodes outer membrane protein F (OmpF), which is a cation-selective porin and is responsible for the passive transport of small molecules across the outer membrane. However, there are few reports about the functions of this gene in . To investigate the role of in detail, an disruption strain (Δ) and a complementation strain (cp) were successfully obtained. We find that OmpF can affect the ability of biofilm formation in . In addition, the variations in biofilm composition of were examined using Raman spectroscopy analyses caused by knocking out , and the result indicated that the levels of certain biofilm components, including lipopolysaccharide (LPS), were significantly decreased in the mutant (Δ). Then, SDS-PAGE was used to further analyze the LPS content, and the result showed that the LPS levels were significantly reduced in the absence of . Therefore, we conclude that OmpF affects biofilm formation in by reducing the amount of LPS. Furthermore, the Δ mutant showed decreased (2.7-fold) adhesion to and invasion of HCT-8 cells. In an antibiotic susceptibility analysis, the Δ mutant showed significantly smaller inhibition zones than the WT, indicating that OmpF had a positive effect on the influx of antibiotics into the cells. In summary, plays a positive regulatory role in the biofilm formation and adhesion/invasion, which is achieved by regulating the amount of LPS, but is a negative regulator of antibiotic resistance in .