The Expression Levels of Virulence and Antibiotic Resistance Genes in Lactococcus Garvieae Exposed To Different Conditions

Abstract

Lactococcus garvieae is the causative agent of lactococcosis, haemorrhagic septicaemia of fish. Lactococcosis causes significant economic loss in aquaculture because it affects many commercially important freshwater and marine species. In this study, it was observed that the bacteria used in the study were identified at a rate of 92.5% in biochemical tests. It was also observed that the L. garvieae agent used in the study was resistant to Gentamicin, Tobramycin, Cefoxitin, Penicillin G, Amoxicillin-Clavulanate, Trimethoprim-Sulfamethoxazole, Clindamycin, Fusidic Acid and Rifampin. When the optimum temperature growth of L. garvieae agent was taken at 21oC for the control group, virulence gene expression level was up-regulated at temperatures of 25 and 37 degrees C, which is in the range where the agent can grow best, while it was down-regulated at 15 and 45 degrees C. Similarly, it was observed that the gene expression level was significantly up-regulated in bacteria that grew at the nearest temperature to 25 degrees C in the expression level of antibiotic resistance gene compared to the 21 degrees C control group, and the expression levels of bacteria growing at other temperatures were lower. Considering these results, it is understood that the effect of temperature on virulence is significantly effective because the bacteria used in the study was isolated from rainbow trout.