Designer fungi: Genetic “dial” fine-tunes mycelium from leather-soft to steel-hard

Mushroom leather just got a genomic upgrade. Researchers at McMaster University have demonstrated that the common split-gill fungus, Schizophyllum commune, can be bred like a crop to yield mycelial films whose mechanical properties span the gap between soft packaging and rigid composites. Starting with four monokaryotic isolates collected from Ecuador to Russia, the team generated 12 dikaryotic offspring—each carrying a unique combination of nuclear and mitochondrial DNA—then grew pure mats by liquid-surface fermentation. After crosslinking with either glycerol or polyethylene glycol (PEG), the 32 resulting films were mechanically tested, chemically profiled and mapped in a material-property chart.

Statistical modelling revealed that nuclear-mitochondrial genotype interactions, together with the choice of crosslinker, explained most of the observed variance. PEG-treated dikaryons carrying α-type mitochondria achieved the highest specific strengths—up to 3 MPa·(m³/kg)—but were brittle, while glycerol-treated counterparts with δ-type mitochondria stretched to 98 % elongation with only moderate strength loss. FT-IR fingerprints confirmed strain-specific cell-wall chemistries that dictate how each crosslinker bonds, suggesting that gene-level selection can pre-programme performance. Importantly, the authors outline two routes to scale the approach: reverting dikaryons to monokaryons via protoplasts to create additional mating combinations, or using protoplast fusion to engineer synthetic strains with desired nuclear-mitochondrial pairings.

The work positions genetic tuning as a low-energy alternative to post-processing additives, paving the way for bespoke mycelium leathers, foams and bioplastics whose properties are written into the genome rather than the factory floor.