Identification of Xylaria cubensis Isolated from Moringa oleifera Leaves and Its Antibacterial Potentials

The escalating threat of antimicrobial resistance underscores the need for novel natural therapeutic agents. Endophytic fungi are recognised as prolific producers of bioactive metabolites with antimicrobial potential. In this study, an endophytic fungus isolated from mature leaves of Moringa oleifera was molecularly identified as closely related to Xylaria cubensis. Its ethyl acetate extract exhibited notable antibacterial activity against Bacillus subtilis, with a minimum inhibitory concentration (MIC) of 25 mg/mL and a minimum bactericidal concentration (MBC) of 100 mg/mL. Scanning electron microscopy revealed pronounced morphological alterations in treated B. subtilis cells, including shrinkage and lysis, consistent with membrane disruption. Gas chromatography–mass spectrometry (GC–MS) analysis identified four major compounds: 2,4‑di‑tert‑butylphenol, pyrrolo[1,2‑a]pyrazine‑1,4‑dione (hexahydro‑3‑(1‑methylethyl)), 3‑furanacetic acid (4‑hexyl‑2,5‑dihydro‑2,5‑dioxo‑) and 1,3,5‑xylenol. These findings highlight the antibacterial potential of endophytic X. cubensis from M. oleifera, particularly against B. subtilis, and support the role of endophytic fungi as promising sources of natural antimicrobial compounds for future therapeutic development.