Antibacterial efficacies of some plant extracts against Aeromonas and Pseudomonas diseases of farmed catfish (Heterobranchus longifilis)

Abstract

Aeromonas and Pseudomonas diseases are responsible for mortalities of some farmed catfish in Nigeria. The objective of the study is to investigate the efficacies of extracts of some plants against Aeromonas and Pseudomonas diseases of Heterobranchus longifilis. Ethanol extracts of Phyllanthus amarus, Allium sativum, Artemisia annua, Citrus limon, Moringa oleifera, Allium cepa and Azadirachta indica were tested against Aeromonas hydrophila and Pseudomonas flourescens of H. longifilis by disc diffusion assay. Extracts of P. amarus, A. sativum, A. annua and C. limon were significantly (P<0.05) more sensitive to A. hydrophila and P. flourescens than M. oleifera, A. cepa and A. indica which were effective against P. flourescens. Minimum inhibitory concentrations (MIC) of the extracts were 25mg/ml for P. amarus and A. annua; 25 and 100mg/ml for C. lemon and A. cepa respectively and 50mg/ml for A. indica. Alkaloid was demonstrated in all plants except A. annua by qualitative methods. Moderate amount (++) of cardiac glycosides was demonstrated in A. sativum, M. oleifera and P. amarus. Saponin (+++) was present in M. oleifera and A. indica while, tannin (++) was present in M. oleifera, P. amarus and A. indica respectively. Phlobatanins and Anthraquinones (++) were present in P. amarus and M. oleifera respectively. Extracts of aforementioned plants have potentials as therapy against Aeromonas hydrophila and Pseudomonas flourescens of farmed catfish.