Study on antibacterial effect of chitosan containing silver oxide and modified bentonite with cationic surfactant against Yersinia ruckeri isolated from rainbow trout (Onchorhynchus mykiss)

In this study, the antibacterial effects of modified bentonite with cationic surfactant and chitosan containing silver oxide against Yersinia ruckeri were investigated under laboratory conditions. These antimicrobial compounds were prepared with bentonite modified with cationic surfactant Tetradecyltrimethylammonium bromide and chitosan modified with silver oxide. The X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy for determination of the structures of bentonite and chitosan composite containing silver oxide showed that the surface and layer structures of them were changed by modification. The antibacterial effects of the two types of antimicrobial compounds on gram-negative bacteria Yersinia ruckeri under laboratory conditions were investigated according to the disk diffusion and macrodilution methods. The results of the disk diffusion method indicated that these compounds had antibacterial properties. The minimum bactericidal concentration (MBC) and the minimum inhibitory concentration (MIC) were determined by the use of microdilution method and counting of colonies on agar plates. The zone of inhibition of chitosan containing silver oxide and modified bentonite were 5.63±0.53 and 1.2±0.16 mm, respectively. The minimum bactericidal concentrations (MBC) of chitosan containing silver oxide and the modified mineral clay compound against Yersinia ruckeri in 10 minutes were 28.57 and 42.85 mg/L. The minimum inhibitory concentration (MIC) of chitosan containing silver oxide and modified clay in 10 minutes was 14.28 mg/L. The results of this study showed that modified bentonite and chitosan containing silver oxide had strong antimicrobial effects and the ability to kill pathogens under laboratory conditions. The bactericidal effect of chitosan containing silver oxide was stronger than the bactericidal effect of modified bentonite clay.