ABSTRACT
Plants have long ago been recognized as being a repository of bioactive phytochemical substances, possessing varieties of activities such as antimicrobial and antioxidant activities. In this research, essential oils from Mangifera indica (mango) and Persea Americana (avocado) seeds were used as antibacterial agents against bacterial isolates from the intestine of goat.
A total of 10 goat intestinal samples were purchased from five different sellers in New Benin market, Benin City. A ten-fold serial dilution was done on intestinal samples, and then isolation and enumeration was done using standard morphological and biochemical identification of the bacterial isolates. Soxhlet extraction method using n-hexane as solvent was employed to obtain oils from the seeds of mango and avocado. Antibacterial susceptibility testing was carried out using Kirby Bauer Disk Diffusion Method to determine the minimum inhibitory concentration (MIC) of the oils on the isolates.The phytochemical and antioxidant properties of the extracted oils were assayed using standard chemical methods. DNA extraction, PCR amplification of the bacteria isolated was carried out using standard procedures.
The resultsshowed that quantitatively, the phytochemicals present in the mango seed oil samples included terpenoids (8.12 ± 0.80 mg/ml), and phenols (31.36 ± 2.51 mg/ml), while avocado samples ranged contained 7.53 ± 0.18 mg/ml of alkaloids and a phonolic content of 43.05 ± 0.18 mg/ml. Total bacterial count of goat intestine ranged from 13.86±0.19×105cfu/g to 55.14±0.52×105cfu/g.Gram-positive bacteria isolated were Staphylococcus aureus and Bacillus subtilis while Gram-negative bacteria were Escherichia coli, Shigella dysenteriae and Salmonella enterica. Escherichia coli was the most occurring bacterial isolate (33.3%) while the least occurring was Shigella dysenteriae (12.1%).The minimum inhibitory concentration of the n-hexane extract ranged from 12.5 – 25.0%, while the minimum bactericidal concentration ranged from 50-75%. Avocado and mango seed oil extracts at 100, 75, 50 and 25 mg/ml concentrations showed clear zones of inhibition against all the bacterial isolates. This study has shown that mango and avocado seed oil have antibacterial activity against bacterial isolates from goat intestine
