ANTIMICROBIAL ACTIVITY OF FUSARIUM OXYSPORUM, ENDOPHYTIC FUNGUS, ISOLATED FROM PSIDIUM GUAJAVA L. (WHITE FRUIT)

The endophytic fungi isolated from the medicinal plant are an essential part of the current drug discovery from natural products. The endophytic fungus isolated from the healthy leaves of Psidium guajava was identified based on microscopic and cultural characteristics. The phylogenetic analysis inferred based on the internal transcribed spacer rRNA region sequence showed close similarity to Fusarium oxysporum. The secondary metabolite produced in solid-state, and submerged fermentation was extracted using ethyl acetate and acetone. The antimicrobial activity of the crude extract was screened by the agar well diffusion method. The inhibitory effect of the extract against bacterial pathogens was evaluated by minimum bactericidal concentration MBC and microdilution MIC methods. The antibacterial activity of the crude extract is significant at p<0.05 level. The extract presented a broad spectrum of inhibition against all the tested bacteria with inhibition zone diameter from 6.67 ± 0.58 mm to 22.00 ± 1.00 mm. The extract showed strong antimicrobial activity with MIC value from 0.156 mg/ml to 5.0 mg/ml and the MBC from 0.625 mg/ml to 10.0 mg/ml. From the tested fungi, the crude extract showed inhibitory activity against Saccharomyces cerevisiae, but no inhibition to Candida albicans and Trichophyton interdigitale. Therefore, the fungus can be an ideal resource for the biological prospecting of antimicrobial agents.