The Relationship between Copper Tolerance and Antibiotic Susceptibility of Vagococcus salmoninarum Isolated from Kılavuzlu Dam Lake

The contamination of aquatic ecosystems by heavy metals has been identified as a significant environmental hazard for aquatic animal species, including fish. The objective of this study was to investigate the tolerance of Vagococcus salmoninarum bacteria to copper and the impact of copper exposure on antibiotic susceptibility. The bacterial isolates, comprising six strains, were obtained from rainbow trout reared in cage culture at Kılavuzlu Dam Lake. The initial assessment of antibiotic susceptibility was conducted using the Kirby-Bauer disc diffusion method, which was subsequently validated through the determination of minimum inhibitory concentration (MIC). The broth microdilution method was employed, with the bacterial isolates exposed to concentrations of copper sulphate ranging from 0.1 to 1 mM. The resistance to multiple antibiotics was altered to be significantly altered following exposure to copper sulphate. The minimum inhibitory concentration (MIC) value of copper was observed to be 0.4 mM against V. salmoninarum. It was noted that V. salmoninarum, which has been exposed to copper in its natural environment, has developed the capacity to withstand stress and has undergone a change in its physiological status.