UJI PATOGENISITAS DAN VIRULENSI Aeromonas hydrophila Stanier PADA IKAN NILA (Oreochromis niloticus Lin.) MELALUI POSTULAT KOCH

Abstract

Bakteri Aeromonas hydrophila bersifat patogen mengakibatkan kematian sebanyak 50% pada ikan nila di keramba jaring apung. Penelitian ini bertujuan untuk meneliti patogenisitas dan virulensi dari dua enzim dan satu toksin haemolisin yang dihasilkan oleh A. hydrophila pada ikan nila yang sehat. Analisis LC-50 menggunakan metode Dragsted Bahrens menghasilkan nilai 4,9 x 106 cfu/mL. Virulensi A. hydrophila diuji menggunakan metode Postulat Koch pada ikan nila sehat menyebabkan tubuh menjadi kemerah-merahan, perdarahan pada permukaan tubuh dan luka borok yang akhirnya menyebabkan kematian.

Aeromonas hydrophila is a highly pathogenic bacterium which caused more than 50% nila’s mortality at the pond culture. The purpose of the research was study on the virulence and pathological effect of two A. hydrophila’s enzymes and one toxin haemolycin on a healthy’s nila fish. Lethal Concentration 50 with injection of A. hydrophila on nila was used as preliminary test to determine bacterial density that caused 50% nila’s mortality. The LC50 was 4,9 X 106 cfu/mL determined by Dragsted Bahrens methods. The A. hydrophila virulence test with The Postulat Koch had been effects on healthy’s nila, with clinical sign were reddening, haemorrhagic all over the body surface, and ulcer which caused mortality.