<![CDATA[Background: Endophytic fungi are known as promising sources of bioactive secondary metabolites with potential antimicrobial properties. Kratom (Mitragyna speciosa Korth.) possesses antimicrobial properties; however, the antimicrobial potential of its associated endophytic fungi remains largely unexplored.Objective: This study aimed to isolate endophytic fungi from kratom plants and evaluate their antimicrobial potential through the agar plug diffusion method as a preliminary screening assay.Method: Endophytic fungi were isolated from healthy kratom plants collected in West Kalimantan, Indonesia. A total of 37 pure isolates were obtained and screened against S. aureus, B. subtilis, P. aeruginosa, S. typhimurium, E. coli, and C. albicans using the diffusion method with agar plugs. Antimicrobial activity was evaluated by measuring inhibition zone diameters. Results: The isolates exhibited varying antimicrobial activities against the tested microorganisms. Isolate MS-D4 demonstrated the strongest antibacterial activity against S. aureus, B. subtilis, P. aeruginosa, and S. typhimurium, although the inhibition zones remained lower than the positive control. No inhibitory activity was observed against E. coli or C. albicans.Conclusion: Endophytic fungi associated with M. speciosa exhibited selective antimicrobial activity and represented promising alternative sources of antimicrobial compounds. Isolate MS-D4 showed the greatest antibacterial potential and warrants further investigation through quantitative antimicrobial assays.]]>
