Perpustakaan Digital ITB

Antimicrobial resistance (AMR) has become an important global health crisis and pushes the need for discovering new antimicrobial compounds. Marine-derived fungi are considered promising sources of secondary metabolites because their ability to adapt to harsh and unique ecological condition. Aspergillus flocculus FSB-27, a marine fungus isolated from coral in Tulamben, Bali, has been observed to show antimicrobial potential. This study aimed to isolate bioactive antimicrobial compounds from FSB-27 using a bioassay-guided fractionation approach. FSB-27 was first fermented under static conditions for 21 days, continued with separate extraction of the biomass and culture media using ethyl acetate. The extracts were screened against Escherichia coli, Acinetobacter baumannii, Staphylococcus aureus, Klebsiella pneumoniae, Candida albicans, and Mycobacterium smegmatis. Only the media extract showed antimicrobial activity and was further partitioned into methanol and n-hexane fractions. The methanol fraction showed the strongest activity and was further separated using vacuum liquid chromatography (VLC). Among the seven subfractions, MM-5 showed the highest activity against E. coli, A. baumannii, S. aureus, and M. smegmatis. Further separation using semi-preparative HPLC yielded two major isolates, MM-5.4.1 and MM-5.4.2. However, antimicrobial activity did not consistently increase throughout the separation process, particularly after subfractionation. The inconsistent trend of bioactivity throughout the separation process may indicate synergistic interactions among metabolites in the earlier fractions and/or degradation during prolonged isolation. The high yield isolate was characterized using ¹H and ¹³C NMR, providing preliminary information for further structural elucidation.