Antimicrobial Activity of Leaf Extracts of Neem (Azadrichta indica) and Tumeric (Curcuma longa) Rhizome Against Some Pathogens Isolated from Clarias gariepinus

Abstract

The antimicrobial activities and diameter of inhibition of aqueous, ethanolic and methanolic extracts of Neem leaves (NL) and Turmeric rhizome (TR) were evaluated against four strains of bacteria isolates from Clarias gariepinus using agar well diffusion method. Minimum Inhibitory Concentration (MIC) and phytochemical screenings of NL and TR were determined using standard methods. The NL and TR of aqueous, ethanolic and methanolic extracts had inhibition zones of 20±0.02 mm 10±0.01 mm, 25±0.02 mm 20±0.01 mm and 19±0.02 mm 20±0.02 mm diameter respectively against Bacillus subtilis; 25±0.03 mm 25±0.01 mm, 22±0.02 mm 25±0.03 mm and 25±0.03 mm 23±0.01 mm against Staphylococcus aureus; 25±0.03 mm 25±0.02 mm, 15±0.01 mm 25±0.02 mm and 15±0.03 mm 20±0.01 mm against Streptococcus iniae; 26±0.02 mm 25±0.01 mm, 17±0.01 mm 15±0.02 mm and 10±0.02 mm 10±0.02 mm diameter against Aeromonas hydrophila; 04±0.01 mm 0.3±0.02 mm, 05±0.02 mm 0.5±0.02 mm and 08±0.02 mm 02±0.03 mm diameter against Aspergillus niger. The MIC of NL and TR of these extracts on the bacteria tested were 1000 μg/ml. The phytochemical screening of these plants indicated the presence of saponins, tannins, flavonoids and polysterols. The plants may be used as promising source of pharmaceutical agents against fish pathogens in the organic aquaculture.