Effect of Ferredoxin Receptor FusA on the Virulence Mechanism of .

is an aerobic Gram-negative bacterium, which is the pathogen of "Visceral white spot disease" in large yellow croaker. is a temperature-dependent bacterial pathogen in fish, which not only reduces the yield of large yellow croaker but also causes continuous transmission of the disease, seriously endangering the healthy development of fisheries. In this study, a mutant strain of was constructed using homologous recombination technology. The results showed that knockout of significantly affected the ability of growth, adhesion, and biofilm formation. Temperature, pH, HO, heavy metals, and the iron-chelating agent were used to treat the wild type of ; the results showed that the expression of was significantly reduced at 4°C, 12°C, and 37°C. The expression of was significantly increased at pH 4 and 5. Cu has a significant inducing effect on the expression of , but Pb has no obvious effect; the expression of was significantly upregulated under different concentrations of HO. The expression of the gene was significantly upregulated in the 0.5~4-μmol/l iron-chelating agent. The expression level of the gene was significantly upregulated after the logarithmic phase. It was suggested that included in the TBDR family not only was involved in the transport of ferredoxin but also played important roles in the pathogenicity and environment adaptation of .