Discovery of New Antimicrobial Metabolites in the Coculture of Medicinal Mushrooms

Bioactivity screening revealed that the antifungal activities of EtOAc extracts from coculture broths of Trametes versicolor SY630 with either Vanderbylia robiniophila SY341 or Ganoderma gibbosum SY1001 were significantly improved compared to that of monocultures. Activity-guided isolation led to the discovery of five aromatic compounds (1-5) from the coculture broth of T. versicolor SY630 and V. robiniophila SY341 and two sphingolipids (6 and 7) from the coculture broth of T. versicolor SY630 and G. gibbosum SY1001. Tramevandins A-C (1-3) and 17-ene-1-deoxyPS (6) are new compounds, while 1-deoxyPS (7) is a new natural product. Notably, compound 2 represents a novel scaffold, wherein the highly modified p-terphenyl bears a benzyl substituent. The absolute configurations of those new compounds were elucidated by X-ray diffraction, ECD calculations, and analysis of physicochemical constants. Compounds 1, 2, and 5-7 exhibited different degrees of antimicrobial activity, and the antifungal activities of compounds 6 and 7 against Candida albicans and Cryptococcus neoformans are comparable to those of fluconazole, nystatin, and sphingosine, respectively. Transcriptome analysis, propidium iodide staining, ergosterol quantification, and feeding assays showed that the isolated sphingolipids can extensively downregulate the late biosynthetic pathway of ergosterol in C. albicans, representing a promising mechanism to combat antibiotic-resistant fungi.