Bioactive potential of Macrocybe titans Pegler, Lodge & Nakasone extracts: antimicrobial effects and phenolic composition

This study investigated the antibacterial properties and phenolic composition of extracts obtained from the giant mushroom Macrocybe titans . Fungal isolates were identified through molecular and phylogenetic analyses based on ITS rDNA sequencing. Extracts were prepared using water and water-miscible organic solvents (isopropanol, ethanol, and methanol) at 25 percent v/v using different extraction approaches. The extracts exhibited antibacterial activity against Staphylococcus aureus, Listeria monocytogenes, Escherichia coli, Pseudomonas aeruginosa , and Klebsiella pneumoniae . Among them, the aqueous extract obtained by static cold extraction (AgFr, run 9) showed the highest antibacterial activity, producing an inhibition zone of 27.8 ± 0.6 mm against S. aureus , while aqueous extracts consistently exhibited low minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values across the tested bacteria. The highest MIC and MBC values were 7.97 mg mL −1 for both E. coli and Pseudomonas aeruginosa . Chemical composition analysis revealed the presence of phenolic compounds and flavonoids, including gallic acid, chlorogenic acid, catechin, and caffeic acid, as identified by UHPLC-DAD. SEM analysis revealed morphological alterations in bacterial cells following treatment with the aqueous extract. Together, these findings highlight M. titans as a promising source of bioactive molecules with potential applications in pharmaceutical formulations and functional foods. The results contribute to expanding the knowledge of unexplored fungal species and support the valorization of natural products as alternatives for the development of novel antimicrobial agents and bio-based products.