Antibacterial Activity and Phylogeny of Griseofulvin Producing Aspergillus and Penicillium Species from Kunduchi Mangrove Sediments, Tanzania

Abstract

Marine fungi are an underrated reservoir of bioactive metabolites for drug discovery. This study focused on fungi isolated from Kunduchi mangrove sediments in Tanzania. In an attempt to investigate the antibacterial activities of marine fungi and uncover their bioactive compounds, ethyl acetate crude extracts of fungal isolates were screened for antibacterial activity against human pathogens (Bacillus subtilis, Staphylococcus aureus and Escherichia coli) followed by compounds identification by Gas Chromatography-Mass Spectrometry (GC/MS). A total of seven fungal isolates were obtained from sediments. Crude extracts from isolate 1 and isolate 2 exhibited significant antibacterial activities with a Minimum Inhibitory Concentration ˃ 3.13 mg/ml against S. aureus and MIC ˃ 0.78 mg/ml for both B. subtilis and E. coli. Furthermore, crude extract analysis by GC/MS detected a substantial amount of griseofulvin from the extracts of both isolates 1 and 2. Using nuclear Large Subunit and Internal Transcribes Spacer molecular markers, griseofulvin-producing fungi were identified as Penicillium aethiopicum and Aspergillus sydowii. Significantly, this marks the first documented instance of griseofulvin production by A. sydowii from the marine environment worldwide. Our research has not only identified a new alternative source of griseofulvin from A. sydowii but also underscores the importance of optimizing culture conditions to enhance the production of bioactive metabolites by the identified mangrove-derived fungi. Future studies may prioritize on optimization of culture conditions as it could have significant implications for the pharmaceutical industry and the development of novel antibacterial agents. Keywords: Antibacterial activity; Griseofulvin; Human pathogens; Mangrove sediment fungi.