Optimizing Antibacterial Activity of Psidium guajava Extracts using Solvent Fractionation method and its Efficacy against Foodborne Pathogens

Guava (Psidium guajava L.) is a common fruit tree that grows in several tropical and subtropical parts of the world. The aim of this research is to justify the use of liquid-liquid fractionation method to determine comparatively the antibacterial potential of crude extracts of Guava leaves and bark against selected organisms obtained from food, the isolates includes; Escherichia coli, Pseudomonas aeruginosa, Streptococcus pneumonia, Bacillus cereus, and Staphylococcus aureus. The phytochemical assay process was conducted using the approved standard methods. Outcome of the analysis of the extracts showed the presence of tannin, phenol, flavonoid, and terpenoid in all the extracts assayed, while steroid and saponin were absent in some. The agar well diffusion method was utilized for the assessment of the antimicrobial properties of the extracts. The ethyl acetate and aqueous fractions from the stem bark and the acetone extract generally showed better antimicrobial activity compared with other extracts from leaves. The extract was active against gram-positive bacteria (Bacillus cereus and Streptococcus pneumoniae) and gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa, Bacillus cereus, and Staphylococcus aureus) at a varying zones of inhibition. The result obtained from this study validates the potential of guava leaves and bark as novel antibacterial agents while further advocating their application for treatment in traditional herbal theraphy. The study also suggests that the optimization of these extracts could maximize their efficiency as an antimicrobial agent and invariably for food safety.