Molecular breeding alters mycelium material properties in the white-rot fungus Pleurotus ostreatus

Mycelium-based materials derived from white-rot fungi have attracted increasing attention as sustainable and eco-friendly alternatives to conventional products. However, their mechanical strength and durability remain relatively inferior. Molecular breeding of white-rot fungi offers a promising strategy to address these limitations. Recent studies have suggested that mycelial density and cell wall structure play key roles in determining the physical properties of mycelium-based materials. In this study, we disrupted mbp1, which encodes a transcription factor required for normal mycelial growth and cell wall synthesis, in the white-rot fungus Pleurotus ostreatus and investigated the effects on mycelium mats and mycelium-based composites. The mycelium mats of the dikaryotic mbp1 disruptants exhibited higher Young's moduli and ultimate tensile strengths than those of the control strain (20b×#61), indicating that mbp1 disruption resulted in stiffer mycelium mats. This may be because of the increased mycelial density in the dikaryotic mbp1 disruptants. In addition, the dikaryotic mbp1 disruptants produced harder mycelium-based composites than the strain 20b×#61. These findings indicate that mbp1 disruption improved the characteristics of mycelium-based composites. To our knowledge, this is the first study demonstrating that molecular breeding can enhance the performance of mycelium-based composites, thereby paving the way for the development of efficient strategies to advance mycelium-based materials. KEY POINTS: • mbp1 disruption resulted in stiffer mycelium mats. • Dikaryotic mbp1 disruptants formed thinner but denser mycelium mats. • mbp1 disruption improved the mechanical strength of mycelium-based composites.