Effect of Ferredoxin Receptor FusA on the Virulence Mechanism of Pseudomonas plecoglossicida

Abstract

Pseudomonas plecoglossicida is an aerobic Gram-negative bacterium, which is the pathogen of “Visceral white spot disease” in large yellow croaker. P. plecoglossicida 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 fusA was constructed using homologous recombination technology. The results showed that knockout of P. plecoglossicida fusA significantly affected the ability of growth, adhesion, and biofilm formation. Temperature, pH, H2O2, heavy metals, and the iron-chelating agent were used to treat the wild type of P. plecoglossicida; the results showed that the expression of fusA was significantly reduced at 4°C, 12°C, and 37°C. The expression of fusA was significantly increased at pH 4 and 5. Cu2+ has a significant inducing effect on the expression of fusA, but Pb2+ has no obvious effect; the expression of fusA was significantly upregulated under different concentrations of H2O2. The expression of the fusA gene was significantly upregulated in the 0.5~4-μmol/l iron-chelating agent. The expression level of the fusA gene was significantly upregulated after the logarithmic phase. It was suggested that fusA 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 P. plecoglossicida.

Enhanced Hemolytic Activity of Mesophilic Aeromonas salmonicida SRW-OG1 Is Brought about by Elevated Temperatures

“…coioides , a common denominator of all these strategies is pushing P . plecoglossicida out of its ideal environment [ 36 , 72 ].…”

“…Differences were compared by t -test, one-way ANOVA followed by Dunnett’s test. p < 0.05 was considered statistically significant [ 36 ].…”

Virulence regulation of Zn2+ uptake system znuABC on mesophilic Aeromonas salmonicida SRW-OG1

“…After that, 200 μL of bacterial suspension was taken to cover the area with mucus evenly, and incubated under dark and damp at 28°C for 2 h, then rinsed with phosphate buffered saline for 3 times, air-dried and fixed again with 4% methanol at 25°C for 30 min. Lastly, the slid glasses were stained with 0.1% crystal violet for 3 min, and observed with optical microscope and imaged with digital camera (magnification, × 1000) ( 45 ). The number of bacteria was counted from the image using IPwin software ( 11 ).…”

The temperature-dependent expression of type II secretion system controls extracellular product secretion and virulence in mesophilic Aeromonas salmonida SRW-OG1

“…According to the previous description ( He et al., 2022 ), we adjusted the concentration of bacterial solution to OD 600 = 0.1, then took 10 μL of bacterial suspension and 190 μL of sterile LB liquid medium, mixed them, and dispensed into 96-well cell culture plates. Eight parallel experiments were set up for each strain.…”

“…There are five accepted subspecies of A. salmonicida : A. salmonicida subsp. Salmonicida (known as typical) , masoucida, achromogenes, pectinolytica , and smithia ( Austin et al., 2007 ; Merino and Tomás, 2016 ; He et al., 2022 ). A. salmonicida has a wide range of hosts, infecting not only infecting salmon and trout ( Du et al., 2015 ), but also Cyprinus carpio ( Maurice and Tinman, 2000 ), Anoplopoma fimbria ( Vasquez et al., 2020 ), Gadusmorhua ( Soto-Dávila et al., 2019 ), Scophthalmus maximus ( Xu et al., 2021 ), and Percafluviatilis ( Rupp et al., 2019 ).…”