This study aims to evaluate the antimicrobial activities of endophytic fungi from marine brown algae Padina sp. collected from Nirwana Beach, Padang, West Sumatera, Indonesia. The isolation of endophytic fungi was conducted using dilution method with Sabouraud Dextrose Agar + Chloramphenicol (SDAC) as a growth medium. Nine fungi strains have been isolated from this alga. Purely isolated fungi were cultivated using rice as a medium at room temperature for 3-4 weeks. The secondary metabolite produced by fungi was extracted using ethyl acetate (EtOAc) as solvent. The antimicrobial activity of EtOAc extracts was tested against Staphylococcus aureus, Escherichia coli, and Candida albicans by using the agar diffusion method. In this research, nine endophytic fungi were isolated from the brown marine algae Padina sp. The results of antimicrobial activity screening showed that one fungal isolate (NT3) was selected as the most active against S. aureus, E. coli, and C. albicans with a diameter of inhibition zone of 20.98±1.56, 17.98±6.58, and 13.60±0 mm, respectively. This selected fungal was identified molecularly as Trichoderma harzianum. We conclude that Trichoderma harzianum can be a source of antimicrobial compounds. However, continuous research is needed to prove their bioactive action.
Key words: Marine algae-derived fungus, Trichoderma harzianum, brown algae, Padina sp., molecular characterization, antimicrobial activity