Objective:To construct the rpoN gene knockout strain (Δ rpoN) and the complemented strain (CΔ rpoN) of Vibrio vulnificus ( V. vulnificus), and investigate the role of the rpoN gene in regulating bacterial motility and biofilm formation. Methods:The Δ rpoN strain of V. vulnificus was constructed using homologous recombination. Bacterial motility was assessed via swimming assays, and flagellar morphology was observed by transmission electron microscopy. Biofilm formation capacity was evaluated using crystal violet and Congo red staining assays, as well as colony morphology analysis. Real-time quantitative RT-PCR (qRT-PCR) was used to detect mRNA levels of target genes associated with flagellar synthesis and biofilm formation in Δ rpoN and the wild-type strains. Results:The V. vulnificus genome harbored a single rpoN gene, encoding a protein with high amino acid sequence similarity to RpoN homologs in other bacterial species. The Δ rpoN strain was successfully constructed. Compared with the wild-type strain, the Δ rpoN strain exhibited complete loss of motility on soft agar plates, absence of flagellar, and downregulated mRNA levels of flagellar synthesis-related genes. Conclusions:In V. vulnificus, RpoN regulates flagellar assembly by modulating the expression of flagellar synthesis genes, thereby controlling bacterial motility and biofilm formation.

Objective:To construct the rpoN gene knockout strain (Δ rpoN) and the complemented strain (CΔ rpoN) of Vibrio vulnificus ( V. vulnificus), and investigate the role of the rpoN gene in regulating bacterial motility and biofilm formation. Methods:The Δ rpoN strain of V. vulnificus was constructed using homologous recombination. Bacterial motility was assessed via swimming assays, and flagellar morphology was observed by transmission electron microscopy. Biofilm formation capacity was evaluated using crystal violet and Congo red staining assays, as well as colony morphology analysis. Real-time quantitative RT-PCR (qRT-PCR) was used to detect mRNA levels of target genes associated with flagellar synthesis and biofilm formation in Δ rpoN and the wild-type strains. Results:The V. vulnificus genome harbored a single rpoN gene, encoding a protein with high amino acid sequence similarity to RpoN homologs in other bacterial species. The Δ rpoN strain was successfully constructed. Compared with the wild-type strain, the Δ rpoN strain exhibited complete loss of motility on soft agar plates, absence of flagellar, and downregulated mRNA levels of flagellar synthesis-related genes. Conclusions:In V. vulnificus, RpoN regulates flagellar assembly by modulating the expression of flagellar synthesis genes, thereby controlling bacterial motility and biofilm formation.