Isolation and Identification of Bacteria from Catfish (Clarias sp.) Attacked by Edwardsiellosis.

Edwardsiellosis, caused by Edwardsiella tarda, appeared in catfish farms and caused mass mortality. The morphology of catfish in Edwardsiellosis resembles the disease of Aeromonas hydrophila but with haemolysis. Catfish samples with Edwardsiellosis morphology were taken from a catfish pond in the Singosari district, East Java. Isolation and identification of Edwardsiella tarda bacteria was tested by morphology, biochemistry, and molecular identity. The clinical symptoms of Edwardsiellosis included a white wound in the head of the Clarias and a red swelling near the pelvic fin. A bacterial biochemistry test showed positive in the production of indole, H₂S in triple sugar iron agar, citrate, malonate reduction and motile, and neither production of acid from D-mannitol, sucrose, trehalose, L-arabinose nor malonate utilization. This bacterium showed positive for β haemolysis. From the 16S rRNA, determined with software phylogeny FR and BLAST, a genetic relationship between Edwardsiella and Aeromonas was shown. Using a form of FASTA from Edwardsiella sp., this bacterium showed an 82% genetic relationship with Edwardsiella tarda ATCC15947. The LD₅₀ of this bacterium was 10⁷ cfu/ml. [ABSTRACT FROM AUTHOR]