Selective breeding and taxonomy of laccate Ganoderma species originating from Finland

Abstract

Ganoderma lucidum has been widely cultivated worldwide due to its bioactive compounds. Agricultural and forestry by-products have been used as growth substrate for the cultivation of G. lucidum. In Finland, there are high volumes of wood biomass by-products that could be used for the cultivation of this fungal species. A laccate Ganoderma species resembling G. lucidum occurs naturally in Finnish forests, but there is lack of information on the wild population. To cultivate Finnish strains of G. lucidum, it is essential to study the variability of the wild populations of the species and select the most appropriate for the industrial use. In this dissertation, the phenotypic variation, the cultivation practices, the β-glucan content, and the phylogeny of laccate Ganoderma originating from Finland have been explored. The growing conditions were adjusted, and the suitability of the strains, supplements, and substrates tested. Finnish strains of G. lucidum were successfully cultivated using wood by-products as substrate. A cold shock treatment of the colonized substrate was needed to trigger the formation of fruiting bodies. Substrates based on Populus tremula and Betula sp. sawdust and wood chips increased the probability of fruiting, fruiting body yield, and β-glucan content of G. lucidum. Substrate based on Pinus sylvestris wood was not suitable for mushroom production, but the fermentation by G. lucidum decreased the lignin content of pine wood, which could be a potential pretreatment for pulping industries. Phenotypic variability of the strains was noted based on mycelial growth, mycelium and fruiting body morphology, fruiting body yield, and their ability to produce β-glucan. Despite the phenotypic variation observed within the Finnish G. lucidum populations, the Finnish isolates presented nearly identical gene regions based on multiple gene regions and grouped together in the phylogenetic trees generated. The Finnish strains of laccate Ganoderma were confirmed to represent a single species according to the phylogenetic analysis. More specimens and molecular data are needed to clarify the classification of laccate Ganoderma from Finland.