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.

Objective:To explore the predictive value of complement and coagulation indicators in sepsis related acute kidney injury (AKI).Methods:Clinical data of 217 patients with sepsis admitted to the Department of Internal Medicine and Intensive Care Unit of Affiliated Hospital of Jiangnan University from January 2018 to June 2019 were retrospectively analyzed. All patients were divided into sepsis with AKI group and without AKI group. Laboratory indicators of all patients were collected, including complement C 3, complement C 4, activated partial thrombin time (APTT), prothrombin time (PT), international normalized ratio (INR), D-dimer, procalcitonin(PCT), etc. logistic regression analysis was used to explore the risk factors of sepsis related AKI. Receiver operating characteristic curve (ROC) was used to evaluate the predictive value of independent risk factors. Results:Among 217 patients, 120 patients developed sepsis related AKI and 97 patients didn′t. PCT, lactic acid, PT, APTT, INR and D-dimer in AKI patients were significantly higher than those without AKI ( P<0.01). Complement C 3 and complement C 4 were significantly lower in AKI group ( P<0.01). Multivariate logistic regression analysis suggested that blood pressure<90/60 mmHg (1 mmHg=0.133 kPa)( OR=3.705, 95% CI 1.536-8.934, P=0.004), increased lactic acid ( OR=1.479, 95% CI 1.089-2.008, P=0.012), decreased complement C 3 ( OR=0.027, 95% CI 0.005-0.152, P<0.001) and prolonged APTT ( OR=1.090, 95% CI 1.047-1.137, P<0.001)were independent risk factors predicting AKI. The area under the ROC curve (AUC) of these multivariates were 0.741 (95% CI 0.675-0.807), 0.798 (95% CI 0.732-0.864), 0.712 (95% CI 0.643-0.781) and 0.716 (95% CI 0.648-0.783) respectively. The relevant sensitivity was 57.5%, 80.8%, 87.5%, 59.2%, and the specificity was 90.7%, 75.3%, 51.5%, 77.3%, respectively. The AUC of the combined four indicators was 0.880 (95 %CI 0.835-0.926) with the sensitivity 75.0% and the specificity 90.7%. Conclusion:The low level of complement C 3 and prolonged APTT predict sepsis related AKI, and the predictive value can be enhanced if hypotension and hyperlactacidemia are added.