Investigation of antimicrobial resistant and effects of some phytochemicals on Yersinia ruckeri

In this thesis, it is aimed to investigate the effects of Moringa oleifera and Sorbus domestica plant extracts on bacterial disease agents Yersinia ruckeri in aquaculture. For this purpose, morphological and biochemical properties of 2 different Y. ruckeri isolates were determined. Then, real-time PCR analysis and gene sequencing of the isolates were identified and identified. Phytochemicals (M. oleifera and S. domestica) and antibiotics (oxytetracycline and enrofloxacin) were used together in the antibiogram test of antibiotics compared to the effect status of antibiotics. In addition, the effects of phytochemicals on Y. ruckeri growth were examined comparatively by spectrophotometrically measuring at 600 nm wavelength every 2 hours according to bacterial growth densities with 10 different groups formed on TSB medium. As a result of the study, it was observed that the isolates formed Gram negative, catalase positive, oxidase negative, mobile and typical Y. ruckeri colonies. After the biochemical tests performed with Microgen ID panel, 99.85% similarity was determined. The isolates overlap with the 16S rRNA gene region after sequence analysis, and 99% of the isolates were similar in phylogenetic analysis. After antibiogram test, oxytetracycline and enrofloxacin antibiotics were resistant to Y. ruckeri but the effects of phytochemicals were less on solid medium (MHA). As a result of the measurements carried out in liquid medium (TSB), it was observed that phytochemicals inhibit the growth of bacteria by 40-50%. As the importance of antibiotic resistance is increasing day by day, we believe that plants that are more alternative and more suitable for antibiotic use today will give positive results in treatment. Keywords: Antibiogram, Fish diseases, Moringa oleifera, Real-Time PCR, Sequencing, Sorbus domestica, Yersinia ruckeri.