Chemodiversity triggering via coculture of endophytic fungi strains of Humicola fuscoatra and Nemania bipapillata isolated from marine red algae

The marine ecosystem has emerged as a promising, yet underexplored, source of natural products due to its rich biodiversity and chemodiversity. Within this domain, endophytic fungi associated with marine algae have shown great potential for providing value-added metabolites and bioprospection [ 1 ]. However, most genes related to biosynthesis in microorganisms remain silenced under standard laboratory growth conditions. Some approaches have been used to trigger activation of silenced biosynthetic pathways such as coculture, which consists of inoculating two or more microorganism strains together, allowing them to induce physiological and chemical stimuli [ 2 ]. In this study, two fungal strains isolated from the red alga Asparagopsis taxiformis were identified as Humicola fuscoatra (At02) and Nemania bipapillata (At05), were grown in Petri dishes containing PDA culture medium and incubated for 10 days at 25º C. The two strains were inoculated both separately and together in Erlenmeyer flasks containing ultrapure water and malt growth medium in static mode for 21 days. After filtration of the fermented broths from the mycelium, the filtrate was partitioned with EtOAc and evaporated to yield the extracts. The control extracts (monoculture) and the coculture extract were analyzed by UPLC-MS/MS and the data submitted to GNPS molecular networking platform [ 3 ], which provided annotation of constituents produced only in coculture as isoreserpin ( 1 ), gentiopicroside ( 2 ), and a cluster with two diterpenes, kaurenoic acid ( 3 ) and 17-hydroxy-15,16-epoxykauran-18-oic acid ( 4 ) and the sesquiterpenoid verrucarol ( 5 ). Such results contribute to the understanding of the chemodiversity of marine endophytic fungi, opening perspectives for the sustainable exploration of this biome, in alignment with the UN-SDGs. Publication History Article published online: 05 March 2026 © 2026. Thieme. All rights reserved. Georg Thieme Verlag KG Oswald-Hesse-Straße 50, 70469 Stuttgart, Germany