Further Biochemical Profiling of Hypholoma fasciculare Metabolome Reveals Its Chemogenetic Diversity

Natural products with novel chemistry are urgently needed to battle the continued increase in microbial drug resistance. Mushroom-forming fungi are underutilized as a source of novel antibiotics in the literature due to their challenging culture preparation and genetic intractability. However, modern fungal molecular and synthetic biology tools have renewed interest in exploring mushroom fungi for novel therapeutic agents. The aims of this study were to investigate the secondary metabolites of nine basidiomycetes, screen their biological and chemical properties, and then investigate the genetic pathways associated with their production. Of the nine fungi selected, Hypholoma fasciculare was revealed to be a highly active antagonistic species, with antimicrobial activity against three different microorganisms: Bacillus subtilis, Escherichia coli, and Saccharomyces cerevisiae. Genomic comparisons and chromatographic studies were employed to characterize more than 15 biosynthetic gene clusters and resulted in the identification of 3,5-dichloromethoxy benzoic acid as a potential antibacterial compound. The biosynthetic gene cluster for this product is also predicted. This study reinforces the potential of mushroom-forming fungi as an underexplored reservoir of bioactive natural products. Access to genomic data, and chemical-based frameworks, will assist the development and application of novel molecules with applications in both the pharmaceutical and agrochemical industries.

Examining the Impact of Winter and Spring Soil Temperatures on the Growth of Hypholoma fasciculare, a Potential Biocontrol Agent Against Armillaria ostoyae, in Pine Plantations

Hypholoma fasciculare is regarded as a potentially effective biocontrol agent against Armillaria root disease. However, trials examining its effectiveness are currently limited to controlled lab conditions and field studies conducted mostly during the summer season. We examined the ability of H. fasciculare to survive and grow underground during the winter and spring seasons to offer insight on its ability to provide year-round protection. Pine blocks inoculated with H. fasciculare were buried in three thinned pine plantations at 30 and 100 cm depths from February 1, 2018 to May 13, 2018 (101 days) to examine how winter and spring soil temperatures at two different soil depths impacted growth. A significant interactive effect of soil depth and month on soil temperature (F3,40 = 15.94, p < 0.001) was observed. Mean growth rates did not vary significantly between the two soil depths (F1,23 = 0.91, p = 0.393) as growth rates were 0.25 ± 0.11 and 0.31 ± 0.10 mm/day at 30 and 100 cm depths, respectively. Our study supports developing H. fasciculare as a biocontrol agent against Armillaria root disease given its ability to grow underground during the winter and early spring seasons, a period during which Armillaria has a reduced growing capacity.

The influence of Hypholoma fasciculare and Phlebiopsis gigantea on the growth of Heterobasidion annosum in vitro

The influence of two saprotrophes — isolates of <i>Hypholoma fasciculare</i> and <i>Phlebiopsis gigantea</i> on the growth of thirty three root pathogen strains — <i>Heterobasidion annosum</i> was analysed. Two methods were used. The different reaction in paired cultures among saprotrophe and pathogen isolates suggest, that one isolate of <i>H. annosum</i> is not enough to study the interaction between this pathogen and saprophytes in vitro irrespective of the method used.