Isolation of aeromonas bacteria from trouts grown in Karkamış Dam Lake and investigation of lithic bacteriophages of aeromonas

The aim of this thesis was to isolate Aeromonas species from rainbow trout reared in Karkamış reservoir that died with disease symptoms and to investigate the presence of specific lytic bacteriophages from environmental samples. In this study, a total of 96 dead rainbow trout and the water-benthos samples were collected from 4 different farms in different locations in Şanlıurfa province at different time periods for bacterial isolation and bacteriophage isolation respectively. After necropsy, 138 examination samples of skin lesions and various organs of the fish were cultured for the isolation of Aeromonas by classical bacterial isolation and identification method. Confirmatory analysis of the isolates obtained was performed by MALDI-TOF MS. Eighteen Aeromonas agents were isolated from fish. Six of these agents were Aeromonas veronii, four were Aeromonas hydrophila, four were Aermonas sobria, two were Aeromonas ichthiosmia, one was Aeromonas caviae and one was Aeromonas bestiarum. Suspicious suspensions were prepared by pre-enrichment of water and benthos samples taken for the detection of bacteriophages. These suspensions were spottested with the isolates obtained and investigated for bacteriophage content. One phage showing lytic activity against Aeromonas hydrophila bacteria obtained from one farm was identified and isolated. The isolated phage was purified by double layer agar method, and the phage titer was determined as 6.40 x 108 Pfu/ml after multiplication with its host in the medium. The optimal MOI value was found to be 0.1 The phage was tested at pH 4-11 and temperature 4-60 °C. The phage was found to be stable in test media with pH 5-9 and temperature 4-40 °C. The bacteriophage was imaged by transmission electron microscopy (TEM) for morphological examination. It was morphologically determined that the phage may belong to the Siphoviridae family. Molecular analysis of the phage revealed that the phage was genetically very similar to the Aeromonas T7-Ah and PZL-Ah152 phages, which were previously identified and entered into GenBank. As a result, it was observed that Aeromonas agents cause infections in fish farms in Karkamış dam in Şanlıurfa region and bacteriophages can be isolated together with the agents. It was concluded that necessary precautions can be taken for the prevention of diseases and further studies should be carried out on the use of bacteriophages in protection and treatment. KEYWORDS: isolation, infection, Aeromonas, bacteriophage, fish