Diversity, Chemical Constituents, and Biological Activities of Endophytic Fungi Isolated from Phallus rubrovolvatus

Abstract

Endophytic fungi have emerged as an important source of bioactive metabolites. Phallus rubrovolvatus is an edible and medicinal mushroom; however, the diversity and biological activities of its endophytic fungi have not yet been studied. This study aimed to evaluate the diversity of endophytic fungi associated with different parts of P. rubrovolvatus, assess their biological activities, and identify the chemical constituents produced by these fungi. In total, 35 endophytic fungal strains were isolated from the cap, volva, stipe, and indusium of P. rubrovolvatus. These isolates belonged to 2 phyla, 4 classes, and 14 genera, with most strains identified belonging to the genera Penicillium and Cladosporium. The antibacterial and antioxidant activities of crude extracts obtained from endophytic fungal fermentation broth were subsequently evaluated. Among the isolates, HTZST13 and HTZST24 exhibited moderate antibacterial activity against Pseudomonas aeruginosa, with inhibition zone diameters of 13.67 mm and 11.67 mm, respectively. Moreover, two strains HTZSB1 and HTZST29 exhibited the strongest antioxidant activities against ABTS, with free radical-scavenging rates of 97.48% and 93.45%, respectively. Liquid chromatography–mass spectrometry analysis revealed that the crude extract of strain HTZSB1 predominantly contained gibberellin A41 and 20-nor-3α-acetoxy-12-hydroxy-abieta-5,7,9,11,13-pentaene. The crude extract of strain HTZST29 predominantly contained 2β-hydroxyjatropholone and 1-[6-(benzyloxy)-3-(tert-butyl)-2-hydroxyphenyl]ethan-1-one. Together, the findings broaden our understanding of the diversity of endophytic fungi associated with P. rubrovolvatus, highlight their antibacterial and antioxidant potential, and provide a foundation for the further development and utilization of endophytic fungal resources from P. rubrovolvatus.