Isolation and Identification of Tenacibaculum maritimum, the Causative Agent of Tenacibaculosis in Farmed Sea Bass (Dicentrarchus labrax) on the Aegean Sea Coast of Turkey

摘要

In this paper we describe the isolation and identification of Tenacibaculum maritimum from infected sea bass by using bacteriological, histopathological, and molecular methods. Fish were reared in five different floating net cage farms and two hatcheries located in several regions on the Aegean Sea coast of Turkey. We observed external erythemic and erosive jaw and operculum superficial or deep ulcerative skin lesions on the head and body surfaces, gill rot, hemorrhagic and erythemic fins in infected individuals, and slight exophthalmia was also detected. In addition, internal hemorrhages and hyperemia in the visceral organs and bloody fluid in the peritoneal cavity were observed. Bacteria isolated from the kidney and skin lesions of the infected fish produced flat, pale colored colonies on Flexibacter maritimus medium (FMM), marine enriched Cytophaga agar (MECA) and Marine Agar (MA) and were identified as Tenacibaculum maritimum, Vibrio sp. and motile or non-motile Aeromonas species. Histopathologically, degeneration and liquefactive necrosis in liver, kidney, and spleen was observed in the individuals infected with Tenacibaculum maritimum. The identification of T. maritimum was performed directly from the infected fish tissue using nested polymerase chain reaction. In this study, T. maritimum induced mostly mixed infection with Vibrio sp. and motile or non-motile aeromonad species in the four fish farms resulting in 25% mortality. However, this bacterium produced an unmixed infection with the same mortality in young sea bass from only one farm.