<![CDATA[Marine endophytic fungi harbor inherent bioactive chemicals that exhibit antimicrobial, antitumor, antiviral, anticancer, and anti-inflammatory properties. The aim of this study was to assess the capability of bioactive chemicals found in endophytic marine fungi to prevent the growth of the harmful bacterium Vibrio harveyi. This research was carried out using a series of procedures, including isolation, selection, antagonistic testing, extraction of active compounds, and antibacterial testing. The process of isolating and selecting endophytic marine fungi was conducted on seaweed and mangrove samples obtained from Buton Island, Southeast Sulawesi. This was performed using Potato Dextrose Agar (PDA). 35 isolates were subjected to antagonistic testing against the pathogenic bacterium V. harveyi, which led to the formation of clear zones with sizes ranging from 2 mm to 21 mm. Extraction was conducted using a maceration technique with ethyl acetate as the solvent. The resulting extract was then concentrated using a rotary evaporator. The extract derived from the marine fungus Aspergillus terreus (WB 1-2) showed the largest inhibitory zone, measuring 21.8±0.3 mm, when tested at a dosage of 2 mg/mL. The diameter of the inhibitory zone of the A. terreus extract was greater than that of the positive control, chloramphenicol (19 mm). These findings suggest that the marine endophytic fungus A. terreus can be used as a natural antibacterial agent to inhibit the growth of infections in aquaculture.]]>
