Use of Cassia alata aqueous extract as a bath treatment to control Pseudomonas anguilliseptica infection in tilapia (Oreochromis niloticus)

Abstract

The aqueous extracts of six plants, Andrographis paniculata, Cassia alata, Centella asiatica, Garcinia mangostana, Punica granatum and Psidium guajava, were investigated for their antimicrobial activity and mode of action against Pseudomonas anguilliseptica, an important fish pathogenic bacterium, which is responsible for economic losses in aquaculture worldwide. Among the tested plant extracts, the C. alata aqueous extract had the strongest inhibitory effect and exhibited a bactericidal mode of action against the pathogenic bacterium. When an infection of tilapia (Oreochromis niloticus) with P. anguilliseptica was induced by intraperitoneal, the median lethal dose (LD50) was determined to be 1.59 x 105 CFU/ml. For the in vivo trial, four different concentrations (25, 50, 75 and 100 ppm) of C. alata aqueous extract were used as bath treatment to remedy the infection. The effect of the extract on the infection was dose-dependent and an extract with the concentration of 100 ppm eliminated mortality of the infected fish without producing any adverse effects on the animals. This study suggests that C. alata aqueous extract has the potential to control fish disease caused by P. anguilliseptica.