Studies of antimicrobial activities of methanolic extract of the stem bark of irvingia gabonensis (baill) on some selected bacterial and fungal isolates

Onunde, Odunayo Abiodun (2015)

xvii,76

Thesis

This study investigated the antimicrobial activities of the methanolic extract of the stem bark of Irvingia gabonensis on some selected bacterial and fungal isolates. It also assessed the antimicrobial activities of the active fraction obtained from the methanolic extract of the stem bark of Irvingia gabonensis and determined the rate of kill, protein leakages as well as potassium ions leakages from the active fraction on the bacterial isolates. This was with a view to determining the antimicrobial properties of Irvingia gabonensis on some selected bacterial and fungal isolates. The stem bark of Irvingia gabonensis was collected from Consecrated Farms Usi – Ekiti, Ekiti State, Nigeria. The stem bark of Irvingia gabonensis was air dried and grounded into powder. Exactly 1280 grams of the stem bark of Irvingia gabonensis were soaked in 10 litres of methanol and water respectively with regular shaking for four days. The filterate obtained were consecrated and lyophilized and kept for further use. The antibacterial and antifungal activities of the plant were determined on fifteen bacterial and ten fungal isolates using agar well diffusion method at 35 mg/ml and 15 mg/ml respectively on Muller – Hinton agar and potato dextrose agar. The methanolic extract of Irvingia gabonensis was further fractionated using four organic solvent: n – Hexane, chloroform, ethylacetate and butanol according to their polarity. The rate of kill, the protein leakage as well as potassium ions leakage of the active fraction were determined on bacterial isolates. The phytochemical screenings of the extract was carried out and susceptibility patterns of the bacterial were also determined. The methanolic stem bark extract of Irvingia gabonensis inhibited the growth of eleven bacterial isolates out of the fifteen bacterial isolates and one fungal isolate out of ten fungal isolatesat 35 mg/ml. The zones of inhibition ranged from 14 ± 0.7 mm for Salmonella typhi to 22 ± 0.7 mm for Bacillus cereus (bacterial isolates)and 20±0.0 mm for the Rhizopus stolonifer(fungal isolate). Out of the four organic solvent used for fractionation, thechloroform fraction of the methanolic stem bark extract of Irvingia gabonensis inhibited the growth of eleven bacterial isolates and one fungal isolate at 15 mg/ml. There was increase in the rate of kill of the isolates by the chloroform fraction of the methanolic stem bark ofIrvingia gabonensis with increase in time and concentrations. The leakages of protein as well as potassium ions suggested that the cell membrane disruption was a mode of action for the chloroform fraction of the methanolic stem bark extract of Irvingia gabonensis. The phytochemical screening result revealed the presence of alkaloids, saponins, tannins, reducing sugar and triterpenes. The susceptibility patterns of the bacterial showed that the most of these bacterial isolates are multi resistance. The study concluded that methanolic stem bark extract and chloroform fraction of the methanolic stem bark extract of Irvingia gabonensisshowed a considerable antimicrobial activities against bacterial and fungal isolates.

Collections: