Evaluation of antibacterial activity of Australian basidiomycetous macrofungi using a high-throughput 96-well plate assay

Context: The production of antimicrobial compounds by macrofungi is not unexpected because they have to compete with other organisms for survival in their natural hostile environment. Previous studies have indicated that macrofungi contain secondary metabolites with a range of pharmacological activities including antimicrobial agents. Objective: To investigate macrofungi for antimicrobial activity due to the increasing need for new antimicrobials as a result of resistance in the bacterial community to existing treatments. Materials and methods: Forty-seven different specimens of macrofungi were collected across Queensland, Australia. Freeze-dried fruiting bodies were sequentially extracted with three solvents: water, ethanol, and hexane. These extracts were tested against representative Gram++ve, Staphylococcus aureus and Gram--ve, Escherichia coli bacteria. Results and discussion: Overall water and ethanol extracts were more effective against S. aureus than E. coli, whereas a small number of hexane extracts showed better results for their antimicrobial potential against E. coli at higher concentrations only. Encouraging results were found for a number of macrofungi in the genera Agaricus (Agaricaceae), Amanita (Amanitaceae), Boletus (Boletaceae), Cantharellus (Cantharellaceae), Fomitopsis (Fomitopsidaceae), Hohenbuehelia (Pleurotaceae), Lentinus (Polyporaceae), Ramaria (Gomphaceae), and Strobilomyces (Boletaceae) showing good growth inhibition of the pathogens tested. Conclusion: The present study establishes the antimicrobial potential of a sample of Australian macrofungi that can serve as potential candidates for the development of new antibiotics.