ABSTRACT

The study evaluated the antibacterial activity of sweet orange (Citrus sinensis) and lime (Ctrus aurantifolia) leaf extract with different solvents (methanol and aqueous) on some pathogenic organisms such as Pseudomonas aeruginosa, Staphylococcus aureus and Salmonella typhi. The fresh leaves of lime (Citrus aurantifolia) and orange (Citrus sinensis) samples were collected at National Root Crop Research Institute Umudike in Ikwuano, Abia State, Nigeria. The result showed that the Methanol and aqueous leaf extracts of lime (Citrus aurantifolia) and Sweet orange (Citrus sinensis) inhibited the growth of the entire bacterial isolates tested. It was observed that the methanol extracts had more significant inhibitory effect on the test organisms than the aqueous extracts. The methanolic leaf extracts of lime (Citrus aurantifolia) recorded a pronounced antibacterial activity against the test pathogens with zones of inhibition varying between 20 mm against Staphylococcus aureus isolate to 23 mm against Pseudomonas aeruginosa then 22mm against  Salmonella typhi at the concentrations of 200mg/ml, whereas the aqueous extracts of lime (Citrus aurantifolia) showed minimal antibacterial activity against the isolates with zones of inhibition varied between 18 mm against Staphylococcus aureus isolate to 21 mm against Pseudomonas aeruginosa then 20mm against  Salmonella typhi at the concentrations of 200mg/ml compared to the methanol extracts. The methanolic leaf extract of Sweet orange (Citrus sinensis) was more effective in inhibiting Salmonella typhi with zone of inhibition ranging between 15mm and 21mm as compared to Pseudomonas aeruginosa with zone of inhibition ranging between 13mm to 20mm then Staphylococcus aureus with zone of inhibition ranging between 13mm to 18mm. The antimicrobial activity of aqueous leaf extracts of Sweet orange (Citrus sinensis) was evaluated against the test organisms and it was more effective in inhibiting Pseudomonas aeruginosa with zone of inhibition ranging between 14mm to 19mm, this is followed by Salmonella typhi with inhibition zone ranging from 14mm to 18mm whereas Staphylococcus aureus had the list inhibition zone ranging from 14mm to 16mm. The results of this study suggest that the leaf extract of sweet orange (Citrus sinensis) and lime (Ctrus aurantifolia) can be used as an antibacterial agent against infections caused by Pseudomonas aeruginosa, Staphylococcus aureus and Salmonella typhi. It could be concludeD that methanol was the best extractive solvent for antibacterial activity of sweet orange (Citrus sinensis) and lime (Ctrus aurantifolia) against all the tested organisms.