Identification of Pathogenic Bacteria on Giant Gourami (Osphronemus goramy Lac.) from Kulon Progo Regency of Yogyakarta Rigen Pawartika, Murwantoko
Department of Fisheries, Faculty of Agriculture, Universitas Gadjah Mada
Abstract
Giant gourami (Osphronemus goramy Lac.) is one of the important economic fish that has been widely cultured in Indonesia because it has many advantages. Bacteria are important pathogens especially in the tropics, given that bacteria can survive well in aquatic environments. The objective of this study is to identify the bacteria causing diseases on giant gourami from which cultured in the Regency of Kulon Progo, Yogyakarta. The diseased fishes were collected from the pond and observed for their external and internal clinical signs. Several organs were fixed and proceededfor histology. The bacteria were isolated from liver and kidney on the Tryticase Soy Agar medium, and followed by subculture to achieve pure culture bacteria. The pathogenic capability of bacteria isolates were proven by Koch^s postulate on juvenile gourami. The identification of the bacteria was conducted on the based of biochemical characteristic as well as 16S rRNA sequences. Isolate SW2H (Pc1)1.2 and SW2G.KC (Pc3)2 were confirmed as the bacterial pathogen in giant gourami as indicated by the similarity of the symptoms between natural infected and reinfected specimens, such as hemorrhage on the body surface, damaged fin, along with necrosis, congestion, and hemorrhage on the tissues. Biochemical characteristic Identification showed that SW2H (Pc1)1.2 and SW2G.KC (Pc3)2 isolates are Aeromonas veronii, which are Gram-negative, motile, catalase and oxidase bacteria. Analysis on 16S rRNA sequences supported that SW2H (Pc1)1.2 and SW2G.KC (Pc3)2 isolates are Aeromonas veronii with the identity with data in Genbank are 99.38% and 99.44% respectively.
