Making Use of Genomic Information to Explore the Biotechnological Potential of Medicinal Mushrooms

Fruiting bodies of fungi are rich in multiple types of bioactive compounds with (potential) pharmaceutical effects. Many kinds of mushrooms are thus highly valued in traditional medicine in different cultures over the world for treatment of diseases and maintenance of good health. Modern science has uncovered functional principles in many medicinal species and assigned beneficial activities (antimicrobial, antiviral, anti-oxidative, immunomodulatory, anti-inflammatory, anti-tumorous, hypotensive, hepatoprotective, antidiabetic/hypoglycemic and hypocholesterolemic, mitogenic/regenerative, etc.) to a wealth of secondary metabolites, peptides, proteins, and sugar-based polymers. Compared to the extensive lists of bioactive compounds and the description of their distinctive effects, the pathways of their biosynthesis and the genes behind are largely understudied. This can now become changed by the many genomes which are provided by large-scale fungal sequencing programs. Among are many assembled genomes for important edible and medicinal mushroom species which can be used in genome mining for genes of interest, both for the synthesis of known products and for the synthesis of novel, so far undetected compounds. Also, genomes of other species offer possibilities to predict genes for the biosynthesis of formerly unnoticed bioactive fungal products of either biochemically already known or novel structure. We present here examples of recent identification of genes and gene clusters for bioactive compounds (different terpenoids, phenolics, polyketides, cyclic peptides, aegerolysins, lectins, protease inhibitors, and ribosome-inactivating proteins) in medicinal and edible fungi. Genome comparisons and gene mining identify related genes for similar products in other species. Usually, genes for medicinally interesting products are found in only a restricted range of species, inconsistently distributed over the fungal taxa. Some of the recognized medicinal species probably have genes for a higher variety of bioactive products than species which are estimated purely for their good edible value or species being commonly neglected for exploitation as food and medicine.