Abstract
Growing data suggest that Aspergillus niger, an endophytic fungus, is a rich source of natural compounds with a wide range of biological properties. This study aimed to examine the antimicrobial and antibiofilm capabilities of the Phragmites australis-derived endophyte against a set of pathogenic bacteria and fungi. The endophytic fungus Aspergillus sp. AP5 was isolated from the leaves of P. australis. The chemical profile of the fungal crude extract was identified by spectroscopic analysis using LC-HRESIMS. The fungal-derived extract was evaluated for its antimicrobial activity towards a set of pathogenic bacterial and fungal strains including Staphylococcus aureus, Pseudomonas aeruginosa, Proteus vulgaris, Klebsiella sp., Candida albicans, and Aspergillus niger. Moreover, antibiofilm activity toward four resistant biofilm-forming bacteria was also evaluated. Additionally, a neural-networking pharmacophore-based visual screening predicted the most probable bioactive compounds in the obtained extract. The AP5-EtOAc extract was found to have potent antibacterial activities against S. aureus, E. coli, and Klebsiella sp., while it exhibited low antibacterial activity toward P. Vulgaris and P. aeruginosa and displayed anticandidal activity. The AP5-EtOAc extract had significant antibiofilm activity in S. aureus, followed by P. aeruginosa. The active metabolites' antifungal and/or antibacterial activities may be due to targeting the fungal CYP 51 and/or the bacterial Gyr-B.