Isolation, identification, and pathogenicity of a virulent Aeromonas jandaei associated with mortality of farmed Pangasianodon hypophthalmus, in India

Abstract

The present study was conducted to investigate the bacterial pathogens involved in the mortality of cultured Pangasianodon hypophthalmus. Diseased fish samples were collected from Maharashtra, India for the isolation of pathogenic bacteria. The pathogenic bacterial isolates were identified using 16S rRNA gene sequencing analysis which revealed that they were 99% identical with Aeromonas jandaei. The bacterial isolates were further characterized using biochemical methods. The lowest bacterial dose which caused 50% cumulative mortality (LD50) in Pangasianodon hypophthalmus was 8.84 X 105 CFU per fish. This was achieved by injecting the fish intraperitoneally with pure culture of A.jandaei isolated from diseased fish. Histopathogical studies revealed necrosis hemorrhaging, and other cellular alterations of different tissues of collected organs viz. gill, liver, and kidney of P. hypophthalmus, observed with the diseased conditions.