Peperomia pellucida leaf extract as immunostimulator in controlling motile aeromonad septicemia due to Aeromonas hydrophila in red hybrid tilapia, Oreochromis spp. farming

Aim: This study was revealed the potential of Peperomia pellucida leaf extract as an immunostimulator agent in controlling motile aeromonad septicemia due to Aeromonas hydrophila in red hybrid tilapia, Oreochromis sp. Materials and Methods: In the present study, minimum inhibitory concentration (MIC) of P. pellucida leaf extract against A. hydrophila was determined through two-fold microbroth dilution method. The plant extract was screening for its active compound using a gas chromatograph mass spectrometer, and the effectiveness of P. pellucida leaf extract as an immunostimulator agent was evaluated. The experimental fish were fed with medicated feed at three different concentrations (25 mg/kg, PP-25; 50 mg/kg, PP-50; and 100 mg/kg, PP-100) of P. pellucida leaf extract for 1 week before they were intraperitoneally exposed to A. hydrophila. Enzyme-linked immunosorbent assay was carried out to determine the value of antibody response to A. hydrophila in fish from a group of fish that received medicated feed, and the percentage of total cumulative mortality of the experimental fish were observed at the end of the experiment. Results: The results showed that the major bioactive compound is phytol (40%), and the MIC value was 31.5 mg/L. The value of antibody response to A. hydrophila in fish from a group of fish which received medicated feed (PP-25, 0.128±0.014 optical density [OD]; PP-50, 0.132±0.003 OD; and PP-100, 0.171±0.02 OD) was found significantly higher (p<0.05) compared to fish did not receive medicated feed (0.00 OD). Whereas, percentage cumulative mortality of fish from all groups of fish received medicated feed (PP-25, 18.0±3.2%; PP-50, 18.2±2.8%; and PP-100, 17.7±1.8%) were found significantly lower (p<0.05) compared to a group of fish did not receive medicated feed (83.2±1.4%). Conclusion: The findings of the present study indicated the huge potential of P. pellucida leaf extract as natural immunostimulator agent for aquaculture uses.