Molecular Characterization of a Fungus Producing Membrane Active Metabolite and Analysis of the Produced Secondary Metabolite

Background: The majority of studies on soil Aspergillus concern the isolation and characterization of the antimicrobial compounds produced by this organism. Our previous studies indicated an isolated Aspergillus strain soil to be of interest, and this subject is further investigated here. Method:  Soil samples of various locations in Iran were collected. Extract from Aspergillus sp. culture was obtained using ethyl acetate fractionation. Antimicrobial activity testing was performed using broth microdilution assay against Escherichia coli, Candida albicans, and Staphylococcus aureus microorganisms. One metabolite PA3-d10 was isolated from these active extracts and identified using thin layer chromatography, preparative thin-layer chromatography, HPLC, 1HNMR (proton nuclear magnetic resonance), 2D NMR, and LC-MS (liquid chromatography-mass spectrometry). Results: According to morphological and biochemical properties as well as ITS rDNA sequencing, we identified an isolate of Aspergillus flavus. The ethyl acetate fraction of the fermentation medium containing membrane active metabolites showed antimicrobial effects against different bacterial and yeast indicator strains. One metabolite from these active extracts was finally identified. Conclusion: Membrane active fraction produced by Aspergillus strain in this research demonstrated antimicrobial activities against bacteria and yeast strains. Therefore, this metabolite can be considered as a potential antimicrobial membrane active agent.