Sponge-associated fungi are attractive targets for the isolation of bioactive natural products with different pharmaceutical purposes. In this investigation, 20 fungi were isolated from 10 different sponge specimens. One isolate, the fungus Penicillium citrinum strain WK-P9, showed activity against Bacillus subtilis JH642 when cultivated in malt extract medium. One new and three known citrinin derivatives were isolated from the extract of this fungus. The structures were elucidated by 1D and 2D NMR spectroscopy, as well as LC-HRMS. Their antibacterial activity against a set of common human pathogenic bacteria and fungi was tested. Compound 2 showed moderate activity against Mycobacterium smegmatis ATCC607 with a minimum inhibitory concentration (MIC) of 32 µg/mL. Compound 4 exhibited moderate growth inhibition against Bacillus subtilis JH642, B. megaterium DSM32, and M. smegmatis ATCC607 with MICs of 16, 16, and 32 µg/mL, respectively. Furthermore, weak activities of 64 µg/mL against B. subtilis DSM10 and S. aureus ATCC25923 were observed for compound 4.
Abstract. Cristianawati O, Sabdaningsih A, Becking LE, Khoeri MM, Nuryadi H, Sabdono A, Trianto A, Radjasa OK. 2019. Biological activity of sponge-associated fungi from Karimunjawa Islands, Indonesia against pathogenic Streptococcus pneumoniae. Biodiversitas 20: 2143-2150. Threats of drug-resistant Streptococcus pneumoniae and the urgent need for new antibiotics require prompt and sustained action for discovering bioactive compounds. This study aimed to isolate sponge-associated fungi as a candidate for sources of drugs. The sponge-associated fungi were screened against the MDR S. pneumoniae. The Deoxyribonucleic Acid (DNA) of fungal isolates that showed the most active was generated by using universal primers ITS1 and ITS4. While the sponge host was identified based on the molecular and by slide section. Out of twenty-nine fungal isolates from 13 marine sponges, S.06.2 isolate produced secondary metabolite that inhibiting the growth of MDR S. pneumoniae. Molecular identification based on the ITS region revealed that the active fungal isolate was closely related to Curvularia lunata, with a 99% similarity. The C. lunata S.06.2 was isolated from sponge Cinachyrella australiensis. Thus, C. lunata S.06.2_ LC315806 can serve as a fruitful strategy for the discovery of novel antibiotics for the treatment of MDR S. pneumoniae.
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