Abstract
Polypores have been applied in traditional Chinese medicine up to the present day, and are becoming more and more popular worldwide. They show a wide range of bioactivities including anti-cancer, anti-inflammatory, antiviral and immuno-enhancing effects. Their secondary metabolites have been the focus of many studies, but the importance of fungal strain for bioactivity and metabolite production has not been investigated so far for these Basidiomycetes. Therefore, we screened several strains from three medicinal polypore species from traditional European medicine: Fomes fomentarius, Fomitopsis pinicola and Piptoporus betulinus. A total of 22 strains were compared concerning their growth rates, optimum growth temperatures, as well as antimicrobial and antifungal properties of ethanolic fruit body extracts. The morphological identification of strains was confirmed based on rDNA ITS phylogenetic analyses. Our results showed that species delimitation is critical due to the presence of several distinct lineages, e.g. within the Fomes fomentarius species complex. Fungal strains within one lineage showed distinct differences in optimum growth temperatures, in secondary metabolite production, and accordingly, in their bioactivities. In general, F. pinicola and P. betulinus extracts exerted distinct antibiotic activities against Bacillus subtilis and Staphylococcus aureus at minimum inhibitory concentrations (MIC) ranging from 31-125 μg mL−1; The antifungal activities of all three polypores against Aspergillus flavus, A. fumigatus, Absidia orchidis and Candida krusei were often strain-specific, ranging from 125-1000 μg mL−1. Our results highlight that a reliable species identification, followed by an extensive screening for a ‘best strain’ is an essential prerequisite for the proper identification of bioactive material.Electronic supplementary materialThe online version of this article (doi:10.1186/s13568-014-0093-0) contains supplementary material, which is available to authorized users.
Highlights
Polypores are a diverse group of Agaricomycetes (Basidiomycota) with tough poroid hymenophores
Fruit body vouchers were deposited in the Mycological Collection of the Herbarium Innsbruck (IB), cultures were deposited in the Jena Microbial Resource Collection (JMRC), sequences were deposited in GenBank
Isolation, and cultivation of fungal strains In sum, nineteen fungal strains were isolated for this study: five strains of F. fomentarius, 11 strains of F. pinicola, and three strains of P. betulinus
Summary
Polypores are a diverse group of Agaricomycetes (Basidiomycota) with tough poroid hymenophores These fungi have been extensively applied in traditional Chinese medicine (TCM) up to the present day (Chang 2000; Chang and Wasser 2012; Hobbs 1995; Ying et al 1987) and are becoming more and more popular in other parts of the world where they are used as a source for medicinal compounds and therapeutic adjuvants, or as Secondary metabolites of medicinal polypores have been the focus of many studies (Grienke et al 2014; Zjawiony 2004), but the importance of fungal strain for Dresch et al AMB Express (2015) 5:4 bioactivity and metabolite production has not been investigated so far. It is recommended to sequence barcoding regions of the investigated fungal material, in order to allow for a later verification of the identification of the fungus
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