Isolation and Screening of Novel Mycophenolic Acid-Producing Fungi from Marine Sediments in Vietnam

Mycophenolic acid (MPA), a secondary metabolite derived from fungal strains, is a therapeutic agent drawing significant attention due to its potential applications in organ transplant rejection, autoimmune disorders, and cancer cell inhibition. It also exhibits potent antiviral, antifungal, and antibacterial properties, positioning it as a candidate for next-generation antibiotics. Research is presently focused on bioprospecting for MPA-producing fungal strains with a broad activity spectrum to enhance clinical efficacy. In this study, 304 fungal strains were isolated from diverse marine sediments in central and southern Vietnam. Thin-layer chromatography (TLC) identified 25 strains capable of synthesizing MPA. Based on morphological characteristics, these were classified into three genera—Penicillium, Aspergillus, and Cladosporium—alongside two unidentified strains. Notably, high-performance liquid chromatography (HPLC) confirmed that strain MBLC9-138 possesses high MPA-producing potential, reaching 463.25 to 632.03 mg/L after 5–7 days of cultivation. Internal transcribed spacer (ITS) sequencing identified this strain as Cladosporium sp. MBLC9-138, marking the first report of MPA biosynthesis within this genus. Furthermore, MPA extracted from this strain exhibited significant antimicrobial activity against Escherichia coli (Gram-negative), Staphylococcus aureus, and Bacillus cereus (Gram-positive), with MIC values of 32, 64, and 16 µg/mL, respectively. These results highlight a promising bioactive candidate that could offer dual therapeutic benefits while potentially minimizing gastrointestinal side effects and antibiotic resistance. Simultaneously, Vietnamese marine sediments continue to be a rich source of material for isolating bioactive microorganisms, particularly MPA-producing strains.