Inhibitory Potential of Ocimum gratissimum L on Bacterial Implicated in ‘Ofe Akwu’ Soup Spoilage

Abstract

Aims: The study evaluated the proximate composition, the bacteria present in freshly spoilt ‘ofe akwu’ soup and inhibitory potential of crude ethanol, methanol and aqueous leaf extract of Ocimum gratissimum on the resulting bacteria. Study Design: This was an analytical study in duplicate. Place and Duration of Study: Department of Microbiology, University of Port Harcourt, Niger Delta University, Amasoma, and South Africa, between July 2015 and December 2016. Methodology: Isolation was done using Nutrient agar medium. Conventional and molecular methods were employed in the identification of the isolates. Proximate analysis and antibacterial activity of O. gratissimumagainst the bacteria were done using standard methods. Results: The proximate analysis shows the chemical composition such as moisture (66.40%), ash (1.42%), carbohydrate (2.74%), protein (6.50%), lipid (14.39%) and fibre (8.55%). The resulting bacteria on the basis of conventional and molecular characterization were identified as Bacillus pumilus strain m414, B. subtilisstrain AIMST 2ME1, B. cereus strain CF7 and Sphingobacterium mizutaii strain AUMC b-161. The ethanol extract (50 to 250 mg/mL) inhibited Bacillus pumilus strain m414 and B. cereus strain CF7 with zones ranging from 7 to 13 mm while the methanol extract (50 to 250 mg/mL) inhibited Bacillus pumilus strain m414, B. subtilis strain AIMST 2ME1 and Sphingobacterium mizutaii strain AUMC b-161 with zones ranging from 5 to 13 mm. None of the isolates was susceptible to the aqueous extract. Conclusion: The study has shown that bacteria inhibition by O. gratissimum crude extract may be of use in the preservation of the soup.