Antimicrobial activity of pomelo (Citrus maxima (burm.) Merr.) crude ethanol extract against Bacillus subtilis, Escherichia coli, and Candida albicans

Abstract

Growing global threat of antimicrobial resistance, increasing prices of medicines, their many side effects and their unavailability in far-flung areas are timely reasons for seeking herbal counterparts of conventional antibiotics. The present study aims to evaluate in vitro the antimicrobial property of the crude ethanolic extract from pomelo (Citrus maxima) peels against Bacillus subtilis, Escherichia coli, and Candida albicans using broth microdilution methods and agar disk diffusion. Results showed minimum inhibitory concentrations (MICs) of 10-20% crude extract for E. coli and 20-40% crude extract for B. subtilis and C. albicans and minimum bactericidal concentrations (MBC) of 40% only on E. coli in the broth microdilution method however, no zones of inhibition in the agar disk diffusion experiment. The antimicrobial properties in pomelo peel crude extract were corroborated by the presence of flavonoids and tannins from phytochemical analysis of the ethanolic extracts. The lack of conclusive results from the agar disk-diffusion method is attributed to the extract’s difficulty to diffuse in the agar medium as compared to the broth medium. The researchers recommend the use broth media in further studies instead of solid agar media.