Screening and Characterization of Exopolysaccharide-Producing Endophytic Fungi

Marine endophytic fungi are microorganisms that inhabit marine plant tissues without harming their hosts. These fungi can produce exopolysaccharides (EPS), which have potential applications in food, pharmaceuticals, and biomaterials. This study aims to screen and characterize EPS-producing marine endophytic fungi. Ten fungi isolates from seaweed, seagrass, and mangroves were cultivated in Czapek-Dox medium, and EPS production was evaluated based on wet and dry biomass yields. Among the isolates, KTR49 produced the highest EPS yield (180±12.26 mg/L) and was further analyzed. FTIR spectroscopy confirmed the presence of hydroxyl (-OH), carbonyl (C=O), and glycosidic (C-O-C) bonds, indicating polysaccharide characteristics. Molecular identification using PCR and phylogenetic analysis classified KTR49 as closely related to Aspergillus flavus. Viscosity analysis showed moderate flow resistance (1.869 ± 0.054 mPa·s), and thermogravimetric analysis (TGA) indicated thermal stability up to 250°C.