Uncovering The Roles Of Basidiomycete-specific Chitin Synthases in Pleurotus ostreatus

White-rot basidiomycetes such as P. ostreatus have multipurpose potential as they can create biomaterial resources by utilizing lignocellulosic biomass which is otherwise difficult and unsustainable to recycle. A key structural component of fungal cell walls is chitin which is produced by transmembrane proteins called chitin synthases (Chs). Chitin synthases have been associated with mycelial structure and strength in ascomycetes, however their roles in basidiomycetes are not as well understood. In my previous study, 7 known chs classes were confirmed and 3 novel basidiomycete-specific chitin synthase (chsb) clades were discovered. 3 of 4 chsb genes in Pleurotus ostreatus (chsb2–4) were disrupted in a ku80 disruptant strain through homologous recombination. After morphological analysis, these genes were found to impact aerial hyphae structure- an important characteristic for industrial suitability of fungi. 

This study utilized these strains to investigate the roles of chsb2-4 in aerial hyphae. Analysis on Yeast-Malt-Glucose agar showed thinner and sparser mycelium for all chsb deletion strains, as well as shorter and rougher aerial hyphae. A significant decrease in cell wall thickness was observed using transmission electron microscopy, however there were no differences in relative percentages of chitin and β-glucan (another key cell wall component). Basidiomycete-specific chitin synthases are responsible for aerial hyphae structure, mycelial sparseness, and cell wall thickness. These genes have clear roles in the structural formation of aerial hyphae, which is important for the industrial usability of fungi. Therefore, basidiomycete-specific chitin synthases are potential targets for changing sparseness and strength of mycelial hyphae to develop improved biomaterials.