Studies were conducted to determine the antibacterial effects of arjun, Terminala arjuna (Roxb.) leaf and turmeric, Curcuma longa (L.) bulb extracts against pathogenic Acinetobacter rudis infection in pangas, Pangasianodon hypophthalmus and rohu, Labeo rohita. The arjun leaf and turmeric bulb were collected from the adjacent area of Bangladesh Agricultural University (BAU), Mymensingh, dried and powdered finely using an automated grinder. Laboratory stocked fish pathogen A. rudis, isolated previously from the body lesions of pangas, was used for challenge test. Biosafety test was performed by aqueous extracts of arjun leaf and turmeric bulb to determine the tolerance of fish. Pangas (7.194±1.09 g) and rohu (3.46±1.12 g) both could tolerate 120 ppm of arjun extracts by dip bath treatment. In case of turmeric bulb extracts, pangas tolerated 120 ppm but rohu could tolerate 90 ppm. An immersion challenge test with 70 P. hypopthalmas and 70 L. rohita was performed under laboratory condition using pre-fixed doses of 4.07×106 and 4.07×107 CFU/mL of A. rudis. After the experimental infection, aqueous extract of turmeric was found to have distinguished effects where 87.5% of infected fish were recovered with prolonged immersion treatment. Water extracts of arjun leaf exhibited 67.5% survival of fish. In-vitro test by acetone extracts of both arjun and turmeric showed inhibition zone against A. rudis at different dosage in comparison with frequently used antibiotics. Thin layer chromatography confirmed the presence of at least one component in the acetone extracts which might be responsible for the antibacterial activity. This preliminary investigation revealed the potential antibacterial effects of T. arjuna leaf and C. longa bulb extracts against A. rudis infection in fish and can be suggested for further detailed studies to establish these medicinal plants for alternative aquaculture health management.
Key words: Terminalia arjuna, extraction, Curcuma longa, infection, Acinetobacter rudis¸ health management.
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