Parafenestella varangrensis sp. nov., a phomenin producing fungus from the Arctic

Driftwood-associated fungi are a less recognized source of secondary metabolites with diverse biological activities. The main aim of this study was to characterize a driftwood-associated Parafenestella (Pleosporales, Ascomycota) species and evaluate the antibacterial and antibiofilm activities of its secondary metabolites. The fungus, isolated from driftwood on Varanger peninsula in the Northeast of Norway, was identified in the genus Parafenestella and is described here as P. varangrensis sp. nov. using a polyphasic taxonomic approach, including a multilocus phylogenetic analysis. Secondary metabolites were isolated from the P. varangrensis extract using flash chromatography followed by preparative high-performance liquid chromatography-mass spectrometry (prep HPLC-MS). The structures of the isolated compounds were elucidated through spectroscopic analysis, including 1D- and 2D-NMR, as well as HR-MS. They were identified as the known α-pyrone-derived polyketides, phomenins A and B, and their antibacterial activity was evaluated. Phomenin A exhibited weak antibacterial activity against Streptococcus agalactiae. Our findings highlight the importance of exploring cryptic biodiversity in less-studied environments, such as driftwood-associated marine-derived fungi in the Arctic, to expand our knowledge of secondary metabolites and their bioactivities.