PhD Dissertation Defense: Kelsey Gray

Mycelial materials, derived from filamentous fungi, offer a sustainable alternative to conventional materials due to their biodegradability and low environmental impact. This research explores a rational phenotype-driven approach to enhance the mechanical properties of pure mycelial materials made from Aspergillus nidulans. We employed three strategies to induce phenotypical changes: disruption of the Cell Wall Integrity Signaling pathway (ΔmpkA), absolute inhibition of asexual development (e.g., ΔbrlA, ΔflbA, ΔfluG, fadAG42R), and controlled partial inhibition of asexual development using α-difluoromethylornithine (DFMO). Structural and biochemical analyses revealed reduced conidiation led to denser hyphal packing and altered cell wall composition, contributing to the increased mechanical strength. Increases in strain at failure was observed in mutants with autolytic dominant phenotypes, suggesting a correlation between autolysis, cell wall composition and mechanical properties. Asexual development was proportionally inhibited by the concentration of DFMO present, however increases in mechanical strength were not 
linear – displaying our ability to tune specific phenotypes to generate specific mechanical changes, and revealing further studies are required to characterize correlation between reduced asexual development and increased mechanical strength. 
These findings demonstrate that modulating asexual development in fungi can systematically enhance mycelial material properties, offering a rational strategy for engineering sustainable biomaterials with tailored mechanical performance. This work advances the potential of fungal-based materials for applications in scalable, eco-friendly material solutions aligned with circular economy principles.